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Date:   Mon, 4 Jan 2021 23:08:53 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>,
        linux-can <linux-can@...r.kernel.org>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jimmy Assarsson <extja@...ser.com>,
        Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        open list <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>
Subject: [PATCH v8] can: usb: etas_es58X: add support for ETAS ES58X CAN USB interfaces

This driver supports the ES581.4, ES582.1 and ES584.1 interfaces from
ETAS GmbH (https://www.etas.com/en/products/es58x.php).

Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>
Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
--

Changes in v8 (2021-01-04):
  - The driver requires CRC16. Modified Kconfig accordingly.

Changes in v7 (2020-11-17):
  - Fix compilation issue if CONFIG_BQL is not set.
Reference: https://lkml.org/lkml/2020/11/15/163

Changes in v6 (2020-11-15):
  - Rebase the patch on the testing branch of linux-can-next.
  - Rename the helper functions according latest changes
    (e.g. can_cc_get_len() -> can_cc_dlc2len())
  - Fix comments of enum es58x_physical_layer and enum
    es58x_sync_edge.

Changes in v5 (2020-11-07):
  - Add support for DLC greater than 8.
  - All other patches from the previous series were either accepted or
    dismissed. As such, this is not a series any more but a single
    patch.

Changes in v4 (2020-10-17):
  - Remove struct es58x_abstracted_can_frame.
    branch is already done inside net/can/af_can.c#can_send().
  - Fix formatting (spaces, comment style).
  - Transform macros into static inline functions when possible.
  - Fix the ctrlmode_supported flags in es581_4.c and removed
    misleading comments in enum es58x_samples_per_bit.
  - Rename enums according to the type.
  - Remove function es58x_can_put_echo_skb().
Reference: https://lkml.org/lkml/2020/10/10/53

Changes in v3 (2020-10-03):
  - Remove all the calls to likely() and unlikely().
Reference: https://lkml.org/lkml/2020/9/30/995

Changes in v2 (2020-09-30):
  - Fixed -W1 warnings (v1 was tested with GCC -WExtra but not with -W1).

v1 (2020-09-27):
 - First release
---
 drivers/net/can/usb/Kconfig                 |   10 +
 drivers/net/can/usb/Makefile                |    1 +
 drivers/net/can/usb/etas_es58x/Makefile     |    3 +
 drivers/net/can/usb/etas_es58x/es581_4.c    |  552 ++++
 drivers/net/can/usb/etas_es58x/es581_4.h    |  206 ++
 drivers/net/can/usb/etas_es58x/es58x_core.c | 2628 +++++++++++++++++++
 drivers/net/can/usb/etas_es58x/es58x_core.h |  724 +++++
 drivers/net/can/usb/etas_es58x/es58x_fd.c   |  658 +++++
 drivers/net/can/usb/etas_es58x/es58x_fd.h   |  242 ++
 9 files changed, 5024 insertions(+)
 create mode 100644 drivers/net/can/usb/etas_es58x/Makefile
 create mode 100644 drivers/net/can/usb/etas_es58x/es581_4.c
 create mode 100644 drivers/net/can/usb/etas_es58x/es581_4.h
 create mode 100644 drivers/net/can/usb/etas_es58x/es58x_core.c
 create mode 100644 drivers/net/can/usb/etas_es58x/es58x_core.h
 create mode 100644 drivers/net/can/usb/etas_es58x/es58x_fd.c
 create mode 100644 drivers/net/can/usb/etas_es58x/es58x_fd.h

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index c1e5d5b570b6..978746ce8873 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -20,6 +20,16 @@ config CAN_ESD_USB2
       This driver supports the CAN-USB/2 interface
       from esd electronic system design gmbh (http://www.esd.eu).

+config CAN_ETAS_ES58X
+    tristate "ETAS ES58X CAN/USB interfaces"
+    select CRC16
+    help
+      This driver supports the ES581.4, ES582.1 and ES584.1 interfaces
+      from ETAS GmbH (https://www.etas.com/en/products/es58x.php).
+
+      To compile this driver as a module, choose M here: the module
+      will be called etas_es58x.
+
 config CAN_GS_USB
     tristate "Geschwister Schneider UG interfaces"
     help
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index aa0f17c0b2ed..748cf31a0d53 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
 obj-$(CONFIG_CAN_EMS_USB) += ems_usb.o
 obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
+obj-$(CONFIG_CAN_ETAS_ES58X) += etas_es58x/
 obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb/
 obj-$(CONFIG_CAN_MCBA_USB) += mcba_usb.o
diff --git a/drivers/net/can/usb/etas_es58x/Makefile
b/drivers/net/can/usb/etas_es58x/Makefile
new file mode 100644
index 000000000000..a129b4aa0215
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_CAN_ETAS_ES58X) += etas_es58x.o
+etas_es58x-y = es58x_core.o es581_4.o es58x_fd.o
diff --git a/drivers/net/can/usb/etas_es58x/es581_4.c
b/drivers/net/can/usb/etas_es58x/es581_4.c
new file mode 100644
index 000000000000..7c111e7ac5eb
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es581_4.c
@@ -0,0 +1,552 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es581_4.c: Adds support to ETAS ES581.4.
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <asm/unaligned.h>
+
+#include "es58x_core.h"
+#include "es581_4.h"
+
+/**
+ * es58x_sizeof_rx_tx_msg() - Calculate the actual length of the
+ *    structure of a rx or tx message.
+ * @msg: message of variable length, must have a dlc field.
+ *
+ * Even if RTR frames have actually no payload, the ES58X devices
+ * still expect it. Must be a macro in order to retrieve the actual
+ * size using offsetof() and typeof().
+ *
+ * Return: length of the message.
+ */
+#define es581_4_sizeof_rx_tx_msg(msg)                \
+    offsetof(typeof(msg), data[can_cc_dlc2len((msg).dlc)])
+
+static u16 es581_4_get_msg_len(const union es58x_urb_cmd *urb_cmd)
+{
+    return get_unaligned_le16(&urb_cmd->es581_4_urb_cmd.msg_len);
+}
+
+static int es581_4_rx_loopback_msg(struct es58x_device *es58x_dev,
+                   const struct es581_4_urb_cmd
+                   *es581_4_urb_cmd)
+{
+    struct net_device *netdev;
+    const struct es581_4_bulk_rx_loopback_msg *bulk_rx_loopback_msg;
+    const struct es581_4_rx_loopback_msg *rx_loopback_msg;
+    u64 *tstamps = es58x_dev->timestamps;
+    u16 msg_len;
+    u32 first_packet_idx, packet_idx;
+    unsigned int dropped = 0;
+    int i, num_element, ret;
+
+    bulk_rx_loopback_msg = &es581_4_urb_cmd->bulk_rx_loopback_msg;
+    msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len) -
+        sizeof(bulk_rx_loopback_msg->channel_no);
+    num_element =
+        es58x_msg_num_element(es58x_dev->dev,
+                  bulk_rx_loopback_msg->rx_loopback_msg,
+                  msg_len);
+    if (num_element <= 0)
+        return num_element;
+
+    ret = es58x_get_netdev(es58x_dev, bulk_rx_loopback_msg->channel_no,
+                   &netdev);
+    if (ret)
+        return ret;
+
+    rx_loopback_msg = &bulk_rx_loopback_msg->rx_loopback_msg[0];
+    first_packet_idx = get_unaligned_le32(&rx_loopback_msg->packet_idx);
+    packet_idx = first_packet_idx;
+    for (i = 0; i < num_element; i++) {
+        rx_loopback_msg = &bulk_rx_loopback_msg->rx_loopback_msg[i];
+        if (get_unaligned_le32(&rx_loopback_msg->packet_idx)
+            == packet_idx - 1) {
+            if (net_ratelimit())
+                netdev_warn(netdev,
+                        "Received loopback packet idx %u twice\n",
+                        packet_idx - 1);
+            dropped++;
+            continue;
+        }
+        if (get_unaligned_le32(&rx_loopback_msg->packet_idx)
+            != packet_idx) {
+            netdev_err(netdev, "Packet idx jumped from %u to %u\n",
+                   packet_idx - 1, rx_loopback_msg->packet_idx);
+            return -EBADMSG;
+        }
+
+        tstamps[i] = get_unaligned_le64(&rx_loopback_msg->timestamp);
+        packet_idx++;
+    }
+
+    netdev->stats.tx_dropped += dropped;
+    return es58x_can_get_echo_skb(netdev, first_packet_idx,
+                      tstamps, num_element - dropped);
+}
+
+static int es581_4_rx_can_msg(struct es58x_device *es58x_dev,
+                  const struct es581_4_urb_cmd *es581_4_urb_cmd,
+                  u16 msg_len)
+{
+    const struct device *dev = es58x_dev->dev;
+    struct net_device *netdev;
+    int pkts, num_element, channel_no, ret;
+
+    num_element = es58x_msg_num_element(dev, es581_4_urb_cmd->rx_can_msg,
+                        msg_len);
+    if (num_element <= 0)
+        return num_element;
+
+    channel_no = es581_4_urb_cmd->rx_can_msg[0].channel_no;
+    ret = es58x_get_netdev(es58x_dev, channel_no, &netdev);
+    if (ret)
+        return ret;
+
+    if (!netif_running(netdev)) {
+        if (net_ratelimit())
+            netdev_info(netdev,
+                    "%s: %s is down, dropping %d rx packets\n",
+                    __func__, netdev->name, num_element);
+        netdev->stats.rx_dropped += num_element;
+        return 0;
+    }
+
+    for (pkts = 0; pkts < num_element; pkts++) {
+        const struct es581_4_rx_can_msg *rx_can_msg =
+            &es581_4_urb_cmd->rx_can_msg[pkts];
+        u64 tstamp = get_unaligned_le64(&rx_can_msg->timestamp);
+        canid_t can_id = get_unaligned_le32(&rx_can_msg->can_id);
+
+        if (channel_no != rx_can_msg->channel_no) {
+            netdev_err(netdev,
+                   "%s: channel_no changed from %d to %d\n",
+                   __func__,
+                   channel_no, rx_can_msg->channel_no);
+            return -EBADMSG;
+        }
+
+        ret = es58x_rx_can_msg(netdev, tstamp, rx_can_msg->data,
+                       can_id, rx_can_msg->flags,
+                       rx_can_msg->dlc);
+        if (ret)
+            break;
+    }
+
+    return ret;
+}
+
+static int es581_4_rx_err_msg(struct es58x_device *es58x_dev,
+                  const struct es581_4_rx_err_msg *rx_err_msg)
+{
+    struct net_device *netdev;
+    enum es58x_err error = get_unaligned_le32(&rx_err_msg->error);
+    int ret;
+
+    ret = es58x_get_netdev(es58x_dev, rx_err_msg->channel_no, &netdev);
+    if (ret)
+        return ret;
+
+    return es58x_rx_err_msg(netdev, error, 0,
+                get_unaligned_le64(&rx_err_msg->timestamp));
+}
+
+static int es581_4_rx_event_msg(struct es58x_device *es58x_dev,
+                const struct es581_4_rx_event_msg *rx_event_msg)
+{
+    struct net_device *netdev;
+    enum es58x_event event = get_unaligned_le32(&rx_event_msg->event);
+    int ret;
+
+    ret = es58x_get_netdev(es58x_dev, rx_event_msg->channel_no, &netdev);
+    if (ret)
+        return ret;
+
+    return es58x_rx_err_msg(netdev, 0, event,
+                get_unaligned_le64(&rx_event_msg->timestamp));
+}
+
+static int es581_4_rx_cmd_ret_u32(struct es58x_device *es58x_dev,
+                  const struct es581_4_urb_cmd *es581_4_urb_cmd,
+                  enum es58x_ret_type ret_type)
+{
+    struct net_device *netdev;
+    const struct es581_4_rx_dev_ret *rx_dev_ret;
+    u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
+    enum es58x_ret_u32 rx_cmd_ret_u32;
+    int ret;
+
+    ret = es58x_check_msg_len(es58x_dev->dev,
+                  es581_4_urb_cmd->rx_dev_ret, msg_len);
+    if (ret)
+        return ret;
+
+    rx_dev_ret = &es581_4_urb_cmd->rx_dev_ret;
+
+    ret = es58x_get_netdev(es58x_dev, rx_dev_ret->channel_no, &netdev);
+    if (ret)
+        return ret;
+
+    rx_cmd_ret_u32 = get_unaligned_le32(&rx_dev_ret->rx_cmd_ret_le32);
+    return es58x_rx_cmd_ret_u32(netdev, ret_type, rx_cmd_ret_u32);
+}
+
+static int es581_4_tx_ack_msg(struct es58x_device *es58x_dev,
+                  const struct es581_4_urb_cmd *es581_4_urb_cmd)
+{
+    struct net_device *netdev;
+    const struct es581_4_tx_ack_msg *tx_ack_msg;
+    u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
+    int ret;
+
+    tx_ack_msg = &es581_4_urb_cmd->tx_ack_msg;
+    ret = es58x_check_msg_len(es58x_dev->dev, *tx_ack_msg, msg_len);
+    if (ret)
+        return ret;
+
+    if (tx_ack_msg->rx_dev_ret_u8 != ES58X_RET_U8_OK)
+        return es58x_rx_dev_ret_u8(es58x_dev->dev,
+                       ES58X_RET_TYPE_TX_MSG,
+                       tx_ack_msg->rx_dev_ret_u8);
+
+    ret = es58x_get_netdev(es58x_dev, tx_ack_msg->channel_no, &netdev);
+    if (ret)
+        return ret;
+
+    return
+        es58x_tx_ack_msg(netdev,
+                 get_unaligned_le16(&tx_ack_msg->tx_free_entries),
+                 ES58X_RET_U32_OK);
+}
+
+static int es581_4_dispatch_rx_cmd(struct es58x_device *es58x_dev,
+                   const struct es581_4_urb_cmd
+                   *es581_4_urb_cmd)
+{
+    const struct device *dev = es58x_dev->dev;
+    u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
+    enum es581_4_rx_type rx_type = es581_4_urb_cmd->rx_can_msg[0].rx_type;
+    int ret = 0;
+
+    switch (rx_type) {
+    case ES581_4_RX_TYPE_MESSAGE:
+        return es581_4_rx_can_msg(es58x_dev, es581_4_urb_cmd, msg_len);
+
+    case ES581_4_RX_TYPE_ERROR:
+        ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_err_msg,
+                      msg_len);
+        if (ret < 0)
+            return ret;
+        return es581_4_rx_err_msg(es58x_dev,
+                      &es581_4_urb_cmd->rx_err_msg);
+
+    case ES581_4_RX_TYPE_EVENT:
+        ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_event_msg,
+                      msg_len);
+        if (ret < 0)
+            return ret;
+        return es581_4_rx_event_msg(es58x_dev,
+                        &es581_4_urb_cmd->rx_event_msg);
+
+    default:
+        dev_err(dev, "%s: Unknown rx_type 0x%02X\n", __func__, rx_type);
+        return -EBADRQC;
+    }
+}
+
+static int es581_4_handle_urb_cmd(struct es58x_device *es58x_dev,
+                  const union es58x_urb_cmd *urb_cmd)
+{
+    const struct es581_4_urb_cmd *es581_4_urb_cmd;
+    const struct device *dev = es58x_dev->dev;
+    u16 msg_len = es581_4_get_msg_len(urb_cmd);
+    int ret;
+
+    es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
+
+    if (es581_4_urb_cmd->cmd_type != ES581_4_CAN_COMMAND_TYPE) {
+        dev_err(dev, "%s: Unknown command type (0x%02X)\n",
+            __func__, es581_4_urb_cmd->cmd_type);
+        return -EBADRQC;
+    }
+
+    switch ((enum es581_4_cmd_id)es581_4_urb_cmd->cmd_id) {
+    case ES581_4_CMD_ID_SET_BITTIMING:
+        return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
+                          ES58X_RET_TYPE_SET_BITTIMING);
+
+    case ES581_4_CMD_ID_ENABLE_CHANNEL:
+        return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
+                          ES58X_RET_TYPE_ENABLE_CHANNEL);
+
+    case ES581_4_CMD_ID_TX_MSG:
+        return es581_4_tx_ack_msg(es58x_dev, es581_4_urb_cmd);
+
+    case ES581_4_CMD_ID_RX_MSG:
+        return es581_4_dispatch_rx_cmd(es58x_dev, es581_4_urb_cmd);
+
+    case ES581_4_CMD_ID_RESET_RX:
+        ret = es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
+                         ES58X_RET_TYPE_RESET_RX);
+        return ret;
+
+    case ES581_4_CMD_ID_RESET_TX:
+        ret = es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
+                         ES58X_RET_TYPE_RESET_TX);
+        return ret;
+
+    case ES581_4_CMD_ID_DISABLE_CHANNEL:
+        return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
+                          ES58X_RET_TYPE_DISABLE_CHANNEL);
+
+    case ES581_4_CMD_ID_TIMESTAMP:
+        ret = es58x_check_msg_len(dev, es581_4_urb_cmd->timestamp,
+                      msg_len);
+        if (ret < 0)
+            return ret;
+        return es58x_rx_timestamp(es58x_dev,
+                      get_unaligned_le64
+                      (&es581_4_urb_cmd->timestamp));
+
+    case ES581_4_CMD_ID_SELF_RECEPTION:
+        return es581_4_rx_loopback_msg(es58x_dev, es581_4_urb_cmd);
+
+    case ES581_4_CMD_ID_DEVICE_ERR:
+        ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_dev_ret_u8,
+                      msg_len);
+        if (ret)
+            return ret;
+        return es58x_rx_dev_ret_u8(es58x_dev->dev,
+                       ES58X_RET_TYPE_DEVICE_ERR,
+                       es581_4_urb_cmd->rx_dev_ret_u8);
+
+    default:
+        dev_warn(dev, "%s: Unexpected command ID: 0x%02X\n",
+             __func__, es581_4_urb_cmd->cmd_id);
+        return -EBADRQC;
+    }
+}
+
+static void es581_4_fill_urb_header(union es58x_urb_cmd *urb_cmd, u8 cmd_type,
+                    u8 cmd_id, u8 channel_idx, u16 msg_len)
+{
+    struct es581_4_urb_cmd *es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
+
+    es581_4_urb_cmd->SOF = cpu_to_le16(es581_4_param.tx_start_of_frame);
+    es581_4_urb_cmd->cmd_type = cmd_type;
+    es581_4_urb_cmd->cmd_id = cmd_id;
+    es581_4_urb_cmd->msg_len = cpu_to_le16(msg_len);
+}
+
+static int es581_4_tx_can_msg(struct es58x_priv *priv, int channel_idx,
+                  u32 packet_idx, const struct sk_buff *skb,
+                  union es58x_urb_cmd *urb_cmd, u32 *urb_cmd_len)
+{
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    struct es581_4_urb_cmd *es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
+    struct can_frame *cf = (struct can_frame *)skb->data;
+    struct es581_4_tx_can_msg *tx_can_msg;
+    u16 msg_len;
+    int ret;
+
+    ret = es58x_check_msg_max_len(es58x_dev->dev,
+                      es581_4_urb_cmd->bulk_tx_can_msg,
+                      es581_4_get_msg_len(urb_cmd) +
+                      sizeof(*tx_can_msg));
+    if (ret)
+        return ret;
+
+    if (can_is_canfd_skb(skb))
+        return -EMSGSIZE;
+
+    /* Fill message contents. */
+    if (*urb_cmd_len == es58x_dev->param->urb_cmd_header_len) {
+        es581_4_fill_urb_header(urb_cmd, ES581_4_CAN_COMMAND_TYPE,
+                    ES581_4_CMD_ID_TX_MSG,
+                    channel_idx, *urb_cmd_len);
+        msg_len = 1;
+    } else {
+        msg_len = le16_to_cpu(es581_4_urb_cmd->msg_len);
+    }
+    tx_can_msg = (struct es581_4_tx_can_msg *)
+        &es581_4_urb_cmd->bulk_tx_can_msg.tx_can_msg_buf[msg_len - 1];
+
+    put_unaligned_le32(es58x_get_raw_can_id(cf), &tx_can_msg->can_id);
+    put_unaligned_le32(packet_idx, &tx_can_msg->packet_idx);
+    put_unaligned_le16((u16)es58x_get_flags(skb), &tx_can_msg->flags);
+    tx_can_msg->channel_no = channel_idx + 1;
+    tx_can_msg->dlc = can_get_cc_dlc(cf, priv->can.ctrlmode);
+
+    memcpy(tx_can_msg->data, cf->data, cf->len);
+
+    /* Calculate new sizes. */
+    es581_4_urb_cmd->bulk_tx_can_msg.num_can_msg++;
+    msg_len += es581_4_sizeof_rx_tx_msg(*tx_can_msg);
+    *urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
+    es581_4_urb_cmd->msg_len = cpu_to_le16(msg_len);
+
+    return 0;
+}
+
+static void es581_4_print_conf(struct net_device *netdev,
+                   struct es581_4_tx_conf_msg *tx_conf_msg)
+{
+    netdev_vdbg(netdev, "bitrate         = %d\n",
+            le32_to_cpu(tx_conf_msg->bitrate));
+    netdev_vdbg(netdev, "sample_point    = %d\n",
+            le32_to_cpu(tx_conf_msg->sample_point));
+    netdev_vdbg(netdev, "samples_per_bit = %d\n",
+            le32_to_cpu(tx_conf_msg->samples_per_bit));
+    netdev_vdbg(netdev, "bit_time        = %d\n",
+            le32_to_cpu(tx_conf_msg->bit_time));
+    netdev_vdbg(netdev, "sjw             = %d\n",
+            le32_to_cpu(tx_conf_msg->sjw));
+    netdev_vdbg(netdev, "sync_edge       = %d\n",
+            le32_to_cpu(tx_conf_msg->sync_edge));
+    netdev_vdbg(netdev, "physical_layer  = %d\n",
+            le32_to_cpu(tx_conf_msg->physical_layer));
+    netdev_vdbg(netdev, "self_reception  = %d\n",
+            le32_to_cpu(tx_conf_msg->self_reception_mode));
+    netdev_vdbg(netdev, "channel_no      = %d\n", tx_conf_msg->channel_no);
+}
+
+static int es581_4_set_bittiming(struct es58x_device *es58x_dev,
+                 int channel_idx)
+{
+    struct es581_4_tx_conf_msg tx_conf_msg = { 0 };
+    struct net_device *netdev = es58x_dev->netdev[channel_idx];
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct can_bittiming *bt = &priv->can.bittiming;
+
+    tx_conf_msg.bitrate = cpu_to_le32(bt->bitrate);
+    /* bt->sample_point is in tenth of percent. Convert it to percent. */
+    tx_conf_msg.sample_point = cpu_to_le32(bt->sample_point / 10U);
+    tx_conf_msg.samples_per_bit = cpu_to_le32(ES58X_SAMPLES_PER_BIT_ONE);
+    tx_conf_msg.bit_time = cpu_to_le32(can_bit_time(bt));
+    tx_conf_msg.sjw = cpu_to_le32(bt->sjw);
+    tx_conf_msg.sync_edge = cpu_to_le32(ES58X_SYNC_EDGE_SINGLE);
+    tx_conf_msg.physical_layer =
+        cpu_to_le32(ES58X_PHYSICAL_LAYER_HIGH_SPEED);
+    tx_conf_msg.self_reception_mode = cpu_to_le32(ES58X_SELF_RECEPTION_ON);
+    tx_conf_msg.channel_no = channel_idx + es581_4_param.channel_idx_offset;
+
+    es581_4_print_conf(netdev, &tx_conf_msg);
+
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_SET_BITTIMING, &tx_conf_msg,
+                  sizeof(tx_conf_msg), channel_idx);
+}
+
+static int es581_4_enable_channel(struct es58x_device *es58x_dev,
+                  int channel_idx)
+{
+    u8 msg = channel_idx + 1;
+
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_ENABLE_CHANNEL, &msg, sizeof(msg),
+                  channel_idx);
+}
+
+static int es581_4_disable_channel(struct es58x_device *es58x_dev,
+                   int channel_idx)
+{
+    u8 msg = channel_idx + 1;
+
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_DISABLE_CHANNEL, &msg, sizeof(msg),
+                  channel_idx);
+}
+
+static int es581_4_reset_rx(struct es58x_device *es58x_dev, int channel_idx)
+{
+    u8 msg = channel_idx + 1;
+
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_RESET_RX, &msg, sizeof(msg),
+                  channel_idx);
+}
+
+static int es581_4_reset_tx(struct es58x_device *es58x_dev, int channel_idx)
+{
+    u8 msg = channel_idx + 1;
+
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_RESET_TX, &msg, sizeof(msg),
+                  channel_idx);
+}
+
+static int es581_4_get_timestamp(struct es58x_device *es58x_dev)
+{
+    return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
+                  ES581_4_CMD_ID_TIMESTAMP, ES58X_EMPTY_MSG,
+                  0, ES58X_CHANNEL_IDX_NA);
+}
+
+/* struct es581_4_bittiming_const - Nominal bittiming constants.
+ *
+ * Nominal bittiming constants for ES581.4 as specified in the
+ * microcontroller datasheet: "Stellaris(R) LM3S5B91 Microcontroller"
+ * table 17-4 "CAN Protocol Ranges" from Texas Instruments.
+ */
+static const struct can_bittiming_const es581_4_bittiming_const = {
+    .name = "ES581.4",
+    .tseg1_min = 1,
+    .tseg1_max = 8,
+    .tseg2_min = 1,
+    .tseg2_max = 8,
+    .sjw_max = 4,
+    .brp_min = 1,
+    .brp_max = 128,
+    .brp_inc = 1
+};
+
+const struct es58x_parameters es581_4_param = {
+    .bittiming_const = &es581_4_bittiming_const,
+    .data_bittiming_const = NULL,
+    .bitrate_max = ES58X_MBPS(1),
+    .clock = {.freq = ES58X_MHZ(50)},
+    .ctrlmode_supported = CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_CC_LEN8_DLC,
+    .tx_start_of_frame = 0xAFAF,
+    .rx_start_of_frame = 0xFAFA,
+    .tx_urb_cmd_max_len = ES581_4_TX_URB_CMD_MAX_LEN,
+    .rx_urb_cmd_max_len = ES581_4_RX_URB_CMD_MAX_LEN,
+    /* Size of internal device TX queue is 330.
+     *
+     * However, we witnessed some ES58X_ERR_PROT_CRC errors from
+     * the device and thus, echo_skb_max was lowered to the
+     * empirical value of 75 which seems stable.
+     *
+     * Root cause of those ES58X_ERR_PROT_CRC errors is still
+     * unclear.
+     */
+    .echo_skb_max = 75,
+#ifdef CONFIG_BQL
+    /* Empirical value. */
+    .dql_limit_min = ES58X_CAN_FRAME_BYTES_MAX * 50,
+#endif
+    .tx_bulk_max = ES581_4_TX_BULK_MAX,
+    .urb_cmd_header_len = ES581_4_URB_CMD_HEADER_LEN,
+    .rx_urb_max = ES58X_RX_URBS_MAX,
+    .tx_urb_max = ES58X_TX_URBS_MAX,
+    .channel_idx_offset = 1
+};
+
+const struct es58x_operators es581_4_ops = {
+    .get_msg_len = es581_4_get_msg_len,
+    .handle_urb_cmd = es581_4_handle_urb_cmd,
+    .fill_urb_header = es581_4_fill_urb_header,
+    .tx_can_msg = es581_4_tx_can_msg,
+    .set_bittiming = es581_4_set_bittiming,
+    .enable_channel = es581_4_enable_channel,
+    .disable_channel = es581_4_disable_channel,
+    .reset_rx = es581_4_reset_rx,
+    .reset_tx = es581_4_reset_tx,
+    .get_timestamp = es581_4_get_timestamp
+};
diff --git a/drivers/net/can/usb/etas_es58x/es581_4.h
b/drivers/net/can/usb/etas_es58x/es581_4.h
new file mode 100644
index 000000000000..5323f45974da
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es581_4.h
@@ -0,0 +1,206 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es581_4.h: Definitions and declarations specific to ETAS
+ * ES581.4.
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#ifndef __ES581_4_H__
+#define __ES581_4_H__
+
+#include <linux/types.h>
+
+#define ES581_4_NUM_CAN_CH 2
+
+#define ES581_4_TX_BULK_MAX 25
+#define ES581_4_RX_BULK_MAX 30
+#define ES581_4_RX_LOOPBACK_BULK_MAX 30
+
+enum es581_4_cmd_type {
+    ES581_4_CAN_COMMAND_TYPE = 0x45
+};
+
+enum es581_4_cmd_id {
+    ES581_4_CMD_ID_OPEN_CHANNEL = 0x01,
+    ES581_4_CMD_ID_CLOSE_CHANNEL = 0x02,
+    ES581_4_CMD_ID_SET_BITTIMING = 0x03,
+    ES581_4_CMD_ID_ENABLE_CHANNEL = 0x04,
+    ES581_4_CMD_ID_TX_MSG = 0x05,
+    ES581_4_CMD_ID_RX_MSG = 0x06,
+    ES581_4_CMD_ID_RESET_RX = 0x0A,
+    ES581_4_CMD_ID_RESET_TX = 0x0B,
+    ES581_4_CMD_ID_DISABLE_CHANNEL = 0x0C,
+    ES581_4_CMD_ID_TIMESTAMP = 0x0E,
+    ES581_4_CMD_ID_RESET_DEVICE = 0x28,
+    ES581_4_CMD_ID_SELF_RECEPTION = 0x71,
+    ES581_4_CMD_ID_DEVICE_ERR = 0x72
+};
+
+enum es581_4_rx_type {
+    ES581_4_RX_TYPE_MESSAGE = 1,
+    ES581_4_RX_TYPE_ERROR = 3,
+    ES581_4_RX_TYPE_EVENT = 4
+};
+
+/**
+ * struct es581_4_tx_conf_msg - Channel configuration.
+ * @bitrate: Bitrate.
+ * @sample_point: Sample point is in percent [0..100].
+ * @samples_per_bit: type enum es58x_samples_per_bit.
+ * @bit_time: Number of time quanta in one bit.
+ * @sjw: Synchronization Jump Width.
+ * @sync_edge: type enum es58x_sync_edge.
+ * @physical_layer: type enum es58x_physical_layer.
+ * @self_reception_mode: type enum es58x_self_reception_mode.
+ * @channel_no: Channel number, starting from 1. Not to be confused
+ *    with channed_idx of the ES58X FD which starts from 0.
+ */
+struct es581_4_tx_conf_msg {
+    __le32 bitrate;
+    __le32 sample_point;
+    __le32 samples_per_bit;
+    __le32 bit_time;
+    __le32 sjw;
+    __le32 sync_edge;
+    __le32 physical_layer;
+    __le32 self_reception_mode;
+    u8 channel_no;
+} __packed;
+
+struct es581_4_tx_can_msg {
+    __le32 can_id;
+    __le32 packet_idx;
+    __le16 flags;
+    u8 channel_no;
+    u8 dlc;
+    u8 data[CAN_MAX_DLEN];
+} __packed;
+
+/* The ES581.4 allows bulk transfer.  */
+struct es581_4_bulk_tx_can_msg {
+    u8 num_can_msg;
+    /* Using type "u8[]" instead of "struct es581_4_tx_can_msg[]"
+     * for tx_msg_buf because each member has a flexible size.
+     */
+    u8 tx_can_msg_buf[ES581_4_TX_BULK_MAX *
+              sizeof(struct es581_4_tx_can_msg)];
+} __packed;
+
+struct es581_4_rx_loopback_msg {
+    __le64 timestamp;
+    __le32 packet_idx;
+} __packed;
+
+struct es581_4_bulk_rx_loopback_msg {
+    u8 channel_no;
+    struct es581_4_rx_loopback_msg
+     rx_loopback_msg[ES581_4_RX_LOOPBACK_BULK_MAX];
+} __packed;
+
+/* Normal Rx CAN Message */
+struct es581_4_rx_can_msg {
+    __le64 timestamp;
+    u8 rx_type;        /* type enum es581_4_rx_type */
+    u8 flags;        /* type enum es58x_flag */
+    u8 channel_no;
+    u8 dlc;
+    __le32 can_id;
+    u8 data[CAN_MAX_DLEN];
+} __packed;
+
+struct es581_4_rx_err_msg {
+    __le64 timestamp;
+    __le16 rx_type;        /* type enum es581_4_rx_type */
+    __le16 flags;        /* type enum es58x_flag */
+    u8 channel_no;
+    u8 __padding[2];
+    u8 dlc;
+    __le32 tag;        /* Related to the CAN filtering. Unused in
this module */
+    __le32 can_id;
+    __le32 error;        /* type enum es58x_error */
+    __le32 destination;    /* Unused in this module */
+} __packed;
+
+struct es581_4_rx_event_msg {
+    __le64 timestamp;
+    __le16 rx_type;        /* type enum es581_4_rx_type */
+    u8 channel_no;
+    u8 __padding;
+    __le32 tag;        /* Related to the CAN filtering. Unused in
this module */
+    __le32 event;        /* type enum es58x_event */
+    __le32 destination;    /* Unused in this module */
+} __packed;
+
+struct es581_4_tx_ack_msg {
+    __le16 tx_free_entries;    /* Number of remaining free entries in
the device TX queue */
+    u8 channel_no;
+    u8 rx_dev_ret_u8;    /* type enum es58x_dev_ret_code_u8 */
+} __packed;
+
+struct es581_4_rx_dev_ret {
+    __le32 rx_cmd_ret_le32;
+    u8 channel_no;
+    u8 __padding[3];
+} __packed;
+
+/**
+ * struct es581_4_urb_cmd - Commands received from or sent to the
+ *    ES581.4 device.
+ * @SOF: Start of Frame.
+ * @cmd_type: Command Type (type: enum es581_4_cmd_type). The CRC
+ *    calculation starts at this position.
+ * @cmd_id: Command ID (type: enum es581_4_cmd_id).
+ * @msg_len: Length of the message, excluding CRC (i.e. length of the
+ *    union).
+ * @tx_conf_msg: Channel configuration.
+ * @bulk_tx_can_msg: Tx messages.
+ * @rx_can_msg: Array of Rx messages.
+ * @bulk_rx_loopback_msg: Loopback messages.
+ * @rx_err_msg: Error message.
+ * @rx_event_msg: Event message.
+ * @tx_ack_msg: Tx acknowledgment message.
+ * @timestamp: Timestamp reply.
+ * @rx_cmd_ret_u8: Rx 8 bits return code (type: enum
+ *    es58x_dev_ret_code_u8).
+ * @raw_msg: Message raw payload.
+ * @reserved_for_crc16_do_not_use: The structure ends with a
+ *    CRC16. Because the structures in above union are of variable
+ *    lengths, we can not predict the offset of the CRC in
+ *    advance. Use functions es58x_get_crc() and es58x_set_crc() to
+ *    manipulate it.
+ */
+struct es581_4_urb_cmd {
+    __le16 SOF;
+    u8 cmd_type;
+    u8 cmd_id;
+    __le16 msg_len;
+
+    union {
+        struct es581_4_tx_conf_msg tx_conf_msg;
+        struct es581_4_bulk_tx_can_msg bulk_tx_can_msg;
+        struct es581_4_rx_can_msg rx_can_msg[ES581_4_RX_BULK_MAX];
+        struct es581_4_bulk_rx_loopback_msg bulk_rx_loopback_msg;
+        struct es581_4_rx_err_msg rx_err_msg;
+        struct es581_4_rx_event_msg rx_event_msg;
+        struct es581_4_tx_ack_msg tx_ack_msg;
+        struct es581_4_rx_dev_ret rx_dev_ret;
+        __le64 timestamp;
+        u8 rx_dev_ret_u8;
+        u8 raw_msg[0];
+    } __packed;
+
+    __le16 reserved_for_crc16_do_not_use;
+} __packed;
+
+#define ES581_4_URB_CMD_HEADER_LEN (offsetof(struct es581_4_urb_cmd, raw_msg))
+#define ES581_4_TX_URB_CMD_MAX_LEN                    \
+    ES58X_SIZEOF_URB_CMD(struct es581_4_urb_cmd, bulk_tx_can_msg)
+#define ES581_4_RX_URB_CMD_MAX_LEN                    \
+    ES58X_SIZEOF_URB_CMD(struct es581_4_urb_cmd, rx_can_msg)
+
+#endif /* __ES581_4_H__ */
diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c
b/drivers/net/can/usb/etas_es58x/es58x_core.c
new file mode 100644
index 000000000000..88891182c3e8
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
@@ -0,0 +1,2628 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es58x_core.c: Core logic to manage the network devices and the
+ * USB interface.
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/usb.h>
+#include <linux/crc16.h>
+#include <linux/spinlock.h>
+#include <asm/unaligned.h>
+
+#include "es58x_core.h"
+
+#define DRV_VERSION "1.03"
+MODULE_AUTHOR("Mailhol Vincent <mailhol.vincent@...adoo.fr>");
+MODULE_AUTHOR("Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>");
+MODULE_DESCRIPTION("Socket CAN driver for ETAS ES58X USB adapters");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL v2");
+
+/* Vendor and product id */
+#define ES58X_MODULE_NAME "etas_es58x"
+#define ES58X_VENDOR_ID 0x108C
+#define ES581_4_PRODUCT_ID 0x0159
+#define ES582_1_PRODUCT_ID 0x0168
+#define ES584_1_PRODUCT_ID 0x0169
+
+/* Table of devices which work with this driver */
+static const struct usb_device_id es58x_id_table[] = {
+    {USB_DEVICE(ES58X_VENDOR_ID, ES581_4_PRODUCT_ID)},
+    {USB_DEVICE(ES58X_VENDOR_ID, ES582_1_PRODUCT_ID)},
+    {USB_DEVICE(ES58X_VENDOR_ID, ES584_1_PRODUCT_ID)},
+    {}            /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, es58x_id_table);
+
+#define es58x_print_hex_dump(buf, len)                    \
+    print_hex_dump(KERN_DEBUG,                    \
+               ES58X_MODULE_NAME " " __stringify(buf) ": ",    \
+               DUMP_PREFIX_NONE, 16, 1, buf, len, false)
+
+#define es58x_print_hex_dump_debug(buf, len)                 \
+    print_hex_dump_debug(ES58X_MODULE_NAME " " __stringify(buf) ": ",\
+                 DUMP_PREFIX_NONE, 16, 1, buf, len, false)
+
+/* The last two bytes of an ES58X command is a CRC16. The first two
+ * bytes (the start of frame) are skipped and the CRC calculation
+ * starts on the third byte.
+ */
+#define ES58X_CRC_CALC_OFFSET    2
+
+/**
+ * es58x_calculate_crc() - Compute the crc16 of a given URB.
+ * @urb_cmd: The URB command for which we want to calculate the CRC.
+ * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
+ *    (ES58X_CRC_CALC_OFFSET + sizeof(crc))
+ *
+ * Return: crc16 value.
+ */
+static u16 es58x_calculate_crc(const union es58x_urb_cmd *urb_cmd, u16 urb_len)
+{
+    u16 crc;
+    ssize_t len = urb_len - ES58X_CRC_CALC_OFFSET - sizeof(crc);
+
+    WARN_ON(len < 0);
+    crc = crc16(0, &urb_cmd->raw_cmd[ES58X_CRC_CALC_OFFSET], len);
+    return crc;
+}
+
+/**
+ * es58x_get_crc() - Get the CRC value of a given URB.
+ * @urb_cmd: The URB command for which we want to get the CRC.
+ * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
+ *    (ES58X_CRC_CALC_OFFSET + sizeof(crc))
+ *
+ * Return: crc16 value.
+ */
+static u16 es58x_get_crc(const union es58x_urb_cmd *urb_cmd, u16 urb_len)
+{
+    u16 crc;
+    const __le16 *crc_addr;
+
+    WARN_ON(urb_len - (ssize_t)sizeof(crc) < 0);
+    crc_addr = (__le16 *)&urb_cmd->raw_cmd[urb_len - sizeof(crc)];
+    crc = get_unaligned_le16(crc_addr);
+    return crc;
+}
+
+/**
+ * es58x_set_crc() - Set the CRC value of a given URB.
+ * @urb_cmd: The URB command for which we want to get the CRC.
+ * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
+ *    (ES58X_CRC_CALC_OFFSET + sizeof(crc))
+ */
+static void es58x_set_crc(union es58x_urb_cmd *urb_cmd, u16 urb_len)
+{
+    u16 crc;
+    __le16 *crc_addr;
+
+    crc = es58x_calculate_crc(urb_cmd, urb_len);
+    crc_addr = (__le16 *)&urb_cmd->raw_cmd[urb_len - sizeof(crc)];
+    put_unaligned_le16(crc, crc_addr);
+}
+
+/**
+ * es58x_check_crc() - Validate the CRC value of a given URB.
+ * @es58x_dev: ES58X device.
+ * @urb_cmd: The URB command for which we want to check the CRC.
+ * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
+ *    (ES58X_CRC_CALC_OFFSET + sizeof(crc))
+ *
+ * Return: zero on success, -EBADMSG if the CRC check fails.
+ */
+static int es58x_check_crc(struct es58x_device *es58x_dev,
+               const union es58x_urb_cmd *urb_cmd, u16 urb_len)
+{
+    u16 calculated_crc = es58x_calculate_crc(urb_cmd, urb_len);
+    u16 expected_crc = es58x_get_crc(urb_cmd, urb_len);
+
+    if (expected_crc != calculated_crc) {
+        dev_err_ratelimited(es58x_dev->dev,
+                    "%s: Bad CRC, urb_len: %d\n",
+                    __func__, urb_len);
+        return -EBADMSG;
+    }
+
+    return 0;
+}
+
+/**
+ * es58x_timestamp_to_ns() - Convert a timestamp value received from a
+ *    ES58X device to nanoseconds.
+ * @timestamp: Timestamp received from a ES58X device.
+ *
+ * The timestamp received from ES58X is expressed in multiple of 0.5
+ * micro seconds. This function converts it in to nanoseconds.
+ *
+ * Return: Timestamp value in nanoseconds.
+ */
+static u64 es58x_timestamp_to_ns(u64 timestamp)
+{
+    const u64 es58x_timestamp_ns_mult_coef = 500ULL;
+
+    return es58x_timestamp_ns_mult_coef * timestamp;
+}
+
+/**
+ * es58x_set_skb_timestamp() - Set the hardware timestamp of an skb.
+ * @netdev: CAN network device.
+ * @skb: socket buffer of a CAN message.
+ * @timestamp: Timestamp received from an ES58X device.
+ *
+ * Used for both received and loopback messages.
+ *
+ * Return: zero on success, -EFAULT if @skb is NULL.
+ */
+static int es58x_set_skb_timestamp(struct net_device *netdev,
+                   struct sk_buff *skb, u64 timestamp)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    struct skb_shared_hwtstamps *hwts;
+
+    hwts = skb_hwtstamps(skb);
+    /* Ignoring overflow (overflow on 64 bits timestamp with nano
+     * second precision would occur after more than 500 years).
+     */
+    hwts->hwtstamp = ns_to_ktime(es58x_timestamp_to_ns(timestamp) +
+                     es58x_dev->realtime_diff_ns);
+
+    return 0;
+}
+
+/**
+ * es58x_rx_timestamp() - Handle a received timestamp.
+ * @es58x_dev: ES58X device.
+ * @timestamp: Timestamp received from a ES58X device.
+ *
+ * Calculate the difference between the ES58X device and the kernel
+ * internal clocks. This difference will be later used as an offset to
+ * convert the timestamps of RX and loopback messages to match the
+ * kernel system time (e.g. convert to UNIX time).
+ *
+ * Return: zero on success.
+ */
+int es58x_rx_timestamp(struct es58x_device *es58x_dev, u64 timestamp)
+{
+    u64 ktime_real_ns = ktime_get_real_ns();
+    u64 device_timestamp = es58x_timestamp_to_ns(timestamp);
+
+    dev_dbg(es58x_dev->dev, "%s: request round-trip time: %llu\n",
+        __func__, ktime_real_ns - es58x_dev->ktime_req_ns);
+
+    es58x_dev->realtime_diff_ns =
+        (es58x_dev->ktime_req_ns + ktime_real_ns) / 2 - device_timestamp;
+    es58x_dev->ktime_req_ns = 0;
+
+    dev_dbg(es58x_dev->dev,
+        "%s: Device timestamp: %llu, diff with kernel: %llu\n",
+        __func__, device_timestamp, es58x_dev->realtime_diff_ns);
+
+    return 0;
+}
+
+/**
+ * es58x_set_realtime_diff_ns() - Calculate difference between the
+ *    clocks of the ES58X device and the kernel
+ * @es58x_dev: ES58X device.
+ *
+ * Request a timestamp from the ES58X device. Once the answer is
+ * received, the timestamp difference will be set by the callback
+ * function es58x_rx_timestamp().
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_set_realtime_diff_ns(struct es58x_device *es58x_dev)
+{
+    if (es58x_dev->ktime_req_ns) {
+        dev_warn(es58x_dev->dev,
+             "%s: Previous request to set timestamp has not completed yet\n",
+             __func__);
+        return -EBUSY;
+    }
+
+    es58x_dev->ktime_req_ns = ktime_get_real_ns();
+    return es58x_dev->ops->get_timestamp(es58x_dev);
+}
+
+/**
+ * es58x_is_can_state_active() - Is the network device in an active
+ *    CAN state?
+ * @netdev: CAN network device.
+ *
+ * The device is considered active if it is able to send or receive
+ * CAN frames, that is to say if it is in any of
+ * CAN_STATE_ERROR_ACTIVE, CAN_STATE_ERROR_WARNING or
+ * CAN_STATE_ERROR_PASSIVE states.
+ *
+ * Caution: when recovering from a bus-off,
+ * net/core/dev.c#can_restart() will call
+ * net/core/dev.c#can_flush_echo_skb() without using any kind of
+ * locks. For this reason, it is critical to guaranty that no TX or
+ * loopback operations (i.e. any access to priv->echo_skb[]) can be
+ * done while this function is returning false.
+ *
+ * Return: true if the device is active, else returns false.
+ */
+static bool es58x_is_can_state_active(struct net_device *netdev)
+{
+    return es58x_priv(netdev)->can.state < CAN_STATE_BUS_OFF;
+}
+
+/**
+ * es58x_echo_skb_stop_threshold() - Determine the limit of how many
+ *    skb slots can be taken before we should stop the network
+ *    queue.
+ * @priv: ES58X private parameters related to the network device.
+ *
+ * We need to save enough free skb slots in order to be able to do
+ * bulk send. This function can be used to determine when to wake or
+ * stop the network queue in regard to the number of skb slots already
+ * taken if the loopback FIFO.
+ *
+ * Return: stop threshold limit.
+ */
+static int es58x_echo_skb_stop_threshold(struct es58x_priv *priv)
+{
+    return priv->can.echo_skb_max - priv->es58x_dev->param->tx_bulk_max + 1;
+}
+
+/**
+ * es58x_netif_wake_queue() - Wake-up the network queue if conditions
+ *    are met.
+ * @netdev: CAN network device.
+ *
+ * If the queue is already awoken, do nothing.
+ *
+ * The conditions to wake up the queue are: a.) The device should be
+ * active (e.g. not in bus off state), b.) The network device must be
+ * up, c.) The echo_skb must have enough free slots for a bulk sent
+ * (c.f. es58x_echo_skb_stop_threshold()), d.) Enough idle URBs should
+ * be available.
+ */
+static void es58x_netif_wake_queue(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    unsigned long echo_skb_flags, tx_urbs_flags;
+
+    if (!netif_queue_stopped(netdev))
+        return;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, echo_skb_flags);
+    if (!es58x_is_can_state_active(netdev))
+        goto echo_skb_unlock;
+    if (netif_running(netdev) &&
+        priv->num_echo_skb < es58x_echo_skb_stop_threshold(priv)) {
+        /* Confirm that we have at least one idle URB per CAN
+         * network device. Otherwise, we might run into race
+         * conditions in the function es58x_start_xmit() which
+         * would force us to return NETDEV_TX_BUSY.
+         */
+        spin_lock_irqsave(&es58x_dev->tx_urbs_idle.lock, tx_urbs_flags);
+        if (atomic_read(&es58x_dev->tx_urbs_idle_cnt) >=
+            es58x_dev->num_can_ch)
+            netif_wake_queue(netdev);
+        spin_unlock_irqrestore(&es58x_dev->tx_urbs_idle.lock,
+                       tx_urbs_flags);
+    }
+ echo_skb_unlock:
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, echo_skb_flags);
+}
+
+/**
+ * es58x_netif_wake_all_queues() - Wake-up all the network queues if
+ *    conditions are met.
+ * @es58x_dev: ES58X device.
+ *
+ * Try to wake-up all the queues associated with a ES58X device. This
+ * function should be used when idle URB resources become available.
+ */
+static void es58x_netif_wake_all_queues(struct es58x_device *es58x_dev)
+{
+    int i;
+
+    for (i = 0; i < es58x_dev->num_can_ch; i++)
+        es58x_netif_wake_queue(es58x_dev->netdev[i]);
+}
+
+/**
+ * es58x_netif_stop_all_queues() - Unconditionally stop all the
+ *    network queues.
+ * @es58x_dev: ES58X device.
+ *
+ * Stop all the queues associated with a ES58X device. This
+ * function should be used when idle URB resources become unavailable.
+ */
+static void es58x_netif_stop_all_queues(struct es58x_device *es58x_dev)
+{
+    int i;
+
+    for (i = 0; i < es58x_dev->num_can_ch; i++)
+        if (es58x_dev->netdev[i])
+            netif_stop_queue(es58x_dev->netdev[i]);
+}
+
+/**
+ * es58x_can_frame_bytes() - Calculate the CAN frame length in bytes
+ *    of a given skb.
+ * @skb: socket buffer of a CAN message.
+ *
+ * Do a rough calculation: bitstuffing is ignored and length in bits
+ * is rounded up to a length in bytes.
+ *
+ * Rationale: this function is to be used for the BQL functions
+ * (__netdev_sent_queue() and netdev_completed_queue()) which expect a
+ * value in bytes. Just using skb->len is insufficient because it will
+ * return the constant value of CAN(FD)_MTU. Doing the bitstuffing
+ * calculation would be too expensive in term of computing resources
+ * for no noticeable gain.
+ *
+ * Remarks: a.)Tthe payload of CAN FD frames with BRS flag are sent at
+ * a different bitrate. Currently, the can-utils canbusload tool does
+ * not support CAN-FD yet and so we could not run any benchmark to
+ * measure the impact. There might be possible improvement here. b.)
+ * The macro ES58X_EFF_BYTES() and ES58X_SFF_BYTES() are for classical
+ * CAN. Need to do the addition for CAN-FD (the value are expected to
+ * be close enough so the impact should be minimal or none).
+ *
+ * Return: length in bytes.
+ */
+static unsigned int es58x_can_frame_bytes(const struct sk_buff *skb)
+{
+    const struct canfd_frame *cf = (const struct canfd_frame *)skb->data;
+    u8 len = cf->can_id & CAN_RTR_FLAG ? 0 : cf->len;
+
+    if (cf->can_id & CAN_EFF_FLAG)
+        return ES58X_EFF_BYTES(len);
+    else
+        return ES58X_SFF_BYTES(len);
+}
+
+/**
+ * es58x_add_skb_idx() - Increment an index of the loopback FIFO.
+ * @priv: ES58X private parameters related to the network device.
+ * @idx: address of the index to be incremented.
+ * @a: the increment. Must be positive and less or equal to
+ *    @priv->can.echo_skb_max.
+ *
+ * Do a modulus addition: set *@idx to (*@idx + @a) %
+ * @priv->can.echo_skb_max.
+ *
+ * Rationale: the modulus operator % takes a decent amount of CPU
+ * cycles (c.f. other division functions such as
+ * include/linux/math64.h:iter_div_u64_rem()).
+ */
+static __always_inline void es58x_add_skb_idx(struct es58x_priv *priv,
+                          u16 *idx, u16 a)
+{
+    *idx += a;
+    if (*idx >= priv->can.echo_skb_max)
+        *idx -= priv->can.echo_skb_max;
+}
+
+/**
+ * es58x_can_free_echo_skb_tail() - Remove the oldest echo skb of the
+ *    loopback FIFO.
+ * @netdev: CAN network device.
+ *
+ * Naming convention: the tail is the beginning of the FIFO, i.e. the
+ * first skb to have entered the FIFO.
+ */
+static void es58x_can_free_echo_skb_tail(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    u16 tail_idx = priv->echo_skb_tail_idx;
+    struct sk_buff *skb = priv->can.echo_skb[tail_idx];
+    unsigned long flags;
+
+    netdev_completed_queue(netdev, 1, es58x_can_frame_bytes(skb));
+    can_free_echo_skb(netdev, tail_idx);
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    es58x_add_skb_idx(priv, &priv->echo_skb_tail_idx, 1);
+    priv->num_echo_skb--;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    netdev->stats.tx_dropped++;
+}
+
+/**
+ * es58x_can_get_echo_skb_recovery() - Try to re-sync the loopback FIFO.
+ * @netdev: CAN network device.
+ * @packet_idx: Index
+ *
+ * This function should not be called under normal circumstances. In
+ * the unlikely case that one or several URB packages get dropped by
+ * the device, the index will get out of sync. Try to recover by
+ * dropping the echo skb packets with older indexes.
+ *
+ * Return: zero if recovery was successful, -EINVAL otherwise.
+ */
+static int es58x_can_get_echo_skb_recovery(struct net_device *netdev,
+                       u32 packet_idx)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    u32 current_packet_idx, first_packet_idx, num_echo_skb;
+    unsigned long flags;
+    int ret = 0;
+
+    netdev->stats.tx_errors++;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    current_packet_idx = priv->current_packet_idx;
+    num_echo_skb = priv->num_echo_skb;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+    first_packet_idx = current_packet_idx - num_echo_skb;
+
+    if (net_ratelimit())
+        netdev_warn(netdev,
+                "Bad loopback packet index: %u. First index: %u, end
index %u, num_echo_skb: %02u/%02u\n",
+                packet_idx, first_packet_idx,
+                current_packet_idx - 1, num_echo_skb,
+                priv->can.echo_skb_max);
+
+    if (packet_idx < first_packet_idx) {
+        if (net_ratelimit())
+            netdev_warn(netdev,
+                    "Received loopback is from the past. Ignoring it\n");
+        ret = -EINVAL;
+    } else if ((s32)(packet_idx - current_packet_idx) >= 0LL) {
+        if (net_ratelimit())
+            netdev_err(netdev,
+                   "Received loopback is from the future. Ignoring it\n");
+        ret = -EINVAL;
+    } else {
+        if (net_ratelimit())
+            netdev_warn(netdev,
+                    "Loopback recovery: dropping %u echo skb from
index %u to %u\n",
+                    packet_idx - first_packet_idx,
+                    first_packet_idx, packet_idx - 1);
+        while (first_packet_idx != packet_idx) {
+            if (num_echo_skb == 0)
+                return -EINVAL;
+            es58x_can_free_echo_skb_tail(netdev);
+            first_packet_idx++;
+            num_echo_skb--;
+        }
+    }
+    return ret;
+}
+
+/**
+ * es58x_can_get_echo_skb() - Get the skb from the loopback FIFO and
+ *    loop it back locally.
+ * @netdev: CAN network device.
+ * @packet_idx: Index of the first packet.
+ * @tstamps: Array of hardware timestamps received from a ES58X device.
+ * @pkts: Number of packets (and so, length of @tstamps).
+ *
+ * Callback function for when we receive a self reception acknowledgment.
+ * Retrieves the skb from the loopback FIFO, sets its hardware timestamp
+ * (the actual time it was sent) and loops it back locally.
+ *
+ * The device has to be active (i.e. network interface UP and not in
+ * bus off state or restarting).
+ *
+ * Packet indexes must be consecutive (i.e. index of first packet is
+ * @packet_idx, index of second packet is @packet_idx + 1 and index of
+ * last packet is @packet_idx + @pkts - 1).
+ *
+ * Return: zero on success.
+ */
+int es58x_can_get_echo_skb(struct net_device *netdev, u32 packet_idx,
+               u64 *tstamps, unsigned int pkts)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    u16 tail_idx;
+    u32 first_packet_idx;
+    unsigned long flags;
+    unsigned int frames_bytes = 0;
+    int i;
+    int ret = 0;
+
+    if (!netif_running(netdev)) {
+        if (net_ratelimit())
+            netdev_info(netdev,
+                    "%s: %s is down, dropping %d loopback packets\n",
+                    __func__, netdev->name, pkts);
+        netdev->stats.tx_dropped++;
+        return 0;
+    } else if (!es58x_is_can_state_active(netdev)) {
+        if (net_ratelimit())
+            netdev_dbg(netdev,
+                   "Bus is off or device is restarting. Ignoring %u
loopback packets from index %u\n",
+                   pkts, packet_idx);
+        /* stats.tx_dropped will be (or was already)
+         * incremented by
+         * drivers/net/can/net/dev.c:can_flush_echo_skb().
+         */
+        return 0;
+    } else if (priv->num_echo_skb == 0) {
+        if (net_ratelimit())
+            netdev_warn(netdev,
+                    "Received %u loopback packets from index: %u but
echo skb queue is empty.\n",
+                    pkts, packet_idx);
+        netdev->stats.tx_dropped += pkts;
+        return 0;
+    }
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    first_packet_idx = priv->current_packet_idx - priv->num_echo_skb;
+    if (first_packet_idx != packet_idx) {
+        spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+        ret = es58x_can_get_echo_skb_recovery(netdev, packet_idx);
+        if (ret < 0) {
+            if (net_ratelimit())
+                netdev_warn(netdev,
+                        "Could not find echo skb for loopback packet
index: %u\n",
+                        packet_idx);
+            return 0;
+        }
+        spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+        first_packet_idx =
+            priv->current_packet_idx - priv->num_echo_skb;
+        WARN_ON(first_packet_idx != packet_idx);
+    }
+    tail_idx = priv->echo_skb_tail_idx;
+    if (priv->num_echo_skb < pkts) {
+        int pkts_drop = pkts - priv->num_echo_skb;
+
+        if (net_ratelimit())
+            netdev_err(netdev,
+                   "Received %u loopback packets but have only %d
echo skb. Dropping %d echo skb\n",
+                   pkts, priv->num_echo_skb, pkts_drop);
+        netdev->stats.tx_dropped += pkts_drop;
+        pkts -= pkts_drop;
+    }
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    for (i = 0; i < pkts; i++) {
+        struct sk_buff *skb = priv->can.echo_skb[tail_idx];
+
+        if (skb) {
+            frames_bytes += es58x_can_frame_bytes(skb);
+            es58x_set_skb_timestamp(netdev, skb, tstamps[i]);
+        }
+        netdev->stats.tx_bytes += can_get_echo_skb(netdev, tail_idx);
+
+        es58x_add_skb_idx(priv, &tail_idx, 1);
+    }
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    es58x_add_skb_idx(priv, &priv->echo_skb_tail_idx, pkts);
+    priv->num_echo_skb -= pkts;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    netdev_completed_queue(netdev, pkts, frames_bytes);
+    netdev->stats.tx_packets += pkts;
+
+    priv->err_passive_before_rtx_success = 0;
+    es58x_netif_wake_queue(netdev);
+
+    return ret;
+}
+
+/**
+ * es58x_can_flush_echo_skb() - Reset the loopback FIFO.
+ * @netdev: CAN network device.
+ *
+ * The echo_skb array of struct can_priv will be flushed by
+ * drivers/net/can/dev.c:can_flush_echo_skb(). This function resets
+ * the parameters of the struct es58x_priv of our device and reset the
+ * queue (c.f. BQL).
+ */
+static void es58x_can_flush_echo_skb(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    unsigned long flags;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    priv->current_packet_idx = 0;
+    priv->echo_skb_tail_idx = 0;
+    priv->echo_skb_head_idx = 0;
+    priv->num_echo_skb = 0;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    netdev_reset_queue(netdev);
+}
+
+/**
+ * es58x_flush_pending_tx_msg() - Reset the buffer for transmission messages.
+ * @netdev: CAN network device.
+ *
+ * es58x_start_xmit() will queue up to tx_bulk_max messages in
+ * &tx_urb buffer and do a bulk send of all messages in one single URB
+ * (c.f. xmit_more flag). When the device recovers from a bus off
+ * state or when the device stops, the tx_urb buffer might still have
+ * pending messages in it and thus need to be flushed.
+ */
+static void es58x_flush_pending_tx_msg(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    unsigned long flags;
+    int i;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    if (priv->tx_urb) {
+        unsigned int frames_bytes = 0;
+        u16 head_idx = priv->echo_skb_head_idx;
+
+        netdev_warn(netdev,
+                "%s: dropping %d tx_msg that were pending for transmission\n",
+                __func__, priv->tx_can_msg_cnt);
+        for (i = 0; i < priv->tx_can_msg_cnt; i++) {
+            frames_bytes +=
+                es58x_can_frame_bytes(priv->can.echo_skb[head_idx]);
+            can_free_echo_skb(netdev, head_idx);
+            es58x_add_skb_idx(priv, &head_idx, 1);
+        }
+        __netdev_sent_queue(netdev, 0, false);
+        netdev_completed_queue(netdev,
+                       priv->tx_can_msg_cnt, frames_bytes);
+        usb_anchor_urb(priv->tx_urb, &priv->es58x_dev->tx_urbs_idle);
+        netdev->stats.tx_dropped += priv->tx_can_msg_cnt;
+
+        atomic_inc(&es58x_dev->tx_urbs_idle_cnt);
+        usb_free_urb(priv->tx_urb);
+    }
+    priv->tx_urb = NULL;
+    priv->tx_can_msg_cnt = 0;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+}
+
+/**
+ * es58x_tx_ack_msg() - Handle acknowledgment messages.
+ * @netdev: CAN network device.
+ * @tx_free_entries: Number of free entries in the device transmit FIFO.
+ * @rx_cmd_ret_u32: error code as returned by the ES58X device.
+ *
+ * ES58X sends an acknowledgment message after a transmission request
+ * is done. This is mandatory for the ES581.4 but is optional (and
+ * deactivated in this driver) for the ES58X_FD family.
+ *
+ * Under normal circumstances, this function should never throw an
+ * error message.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+int es58x_tx_ack_msg(struct net_device *netdev, u16 tx_free_entries,
+             enum es58x_ret_u32 rx_cmd_ret_u32)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+
+    if (tx_free_entries <= priv->es58x_dev->param->tx_bulk_max) {
+        if (net_ratelimit())
+            netdev_err(netdev,
+                   "Only %d entries remaining in device queue,
echo_skb_max: %d, num_echo_skb: %d, tx_free_entries + num_echo_skb:
%d\n",
+                   tx_free_entries, priv->can.echo_skb_max,
+                   priv->num_echo_skb,
+                   tx_free_entries + priv->num_echo_skb);
+        netif_stop_queue(netdev);
+    }
+
+    return es58x_rx_cmd_ret_u32(netdev, ES58X_RET_TYPE_TX_MSG,
+                    rx_cmd_ret_u32);
+}
+
+/**
+ * es58x_rx_can_msg() - Handle a received a CAN message.
+ * @netdev: CAN network device.
+ * @timestamp: Hardware time stamp (only relevant in rx branches).
+ * @data: CAN payload.
+ * @can_id: CAN ID.
+ * @es58x_flags: Please refer to enum es58x_flag.
+ * @dlc: Data Length Code (raw value).
+ *
+ * Fill up a CAN skb and post it.
+ *
+ * This function handles the case where the DLC of a classical CAN
+ * frame is greater than CAN_MAX_DLEN (c.f. the len8_dlc field of
+ * struct can_frame).
+ *
+ * Return: zero on success.
+ */
+int es58x_rx_can_msg(struct net_device *netdev, u64 timestamp, const u8 *data,
+             canid_t can_id, enum es58x_flag es58x_flags, u8 dlc)
+{
+    struct canfd_frame *cfd;
+    struct can_frame *ccf;
+    struct sk_buff *skb;
+    u8 len;
+    bool is_can_fd = !!(es58x_flags & ES58X_FLAG_FD_DATA);
+
+    if (dlc > CAN_MAX_RAW_DLC) {
+        netdev_err(netdev,
+               "%s: DLC is %d but maximum should be %d\n",
+               __func__, dlc, CAN_MAX_RAW_DLC);
+        return -EMSGSIZE;
+    }
+
+    if (is_can_fd) {
+        len = can_fd_dlc2len(dlc);
+        skb = alloc_canfd_skb(netdev, &cfd);
+    } else {
+        len = can_cc_dlc2len(dlc);
+        skb = alloc_can_skb(netdev, &ccf);
+        cfd = (struct canfd_frame *)ccf;
+    }
+
+    if (!skb) {
+        netdev->stats.rx_dropped++;
+        return -ENOMEM;
+    }
+    cfd->can_id = can_id;
+    if (es58x_flags & ES58X_FLAG_EFF)
+        cfd->can_id |= CAN_EFF_FLAG;
+    if (is_can_fd) {
+        cfd->len = len;
+        if (es58x_flags & ES58X_FLAG_FD_BRS)
+            cfd->flags |= CANFD_BRS;
+        if (es58x_flags & ES58X_FLAG_FD_ESI)
+            cfd->flags |= CANFD_ESI;
+    } else {
+        can_frame_set_cc_len(ccf, dlc, es58x_priv(netdev)->can.ctrlmode);
+        if (es58x_flags & ES58X_FLAG_RTR) {
+            ccf->can_id |= CAN_RTR_FLAG;
+            len = 0;
+        }
+    }
+    memcpy(cfd->data, data, len);
+    netdev->stats.rx_packets++;
+    netdev->stats.rx_bytes += len;
+
+    es58x_set_skb_timestamp(netdev, skb, timestamp);
+    netif_rx(skb);
+
+    es58x_priv(netdev)->err_passive_before_rtx_success = 0;
+
+    return 0;
+}
+
+/**
+ * es58x_rx_err_msg() - Handle a received CAN event or error message.
+ * @netdev: CAN network device.
+ * @error: Error code.
+ * @event: Event code.
+ * @timestamp: Timestamp received from a ES58X device.
+ *
+ * Handle the errors and events received by the ES58X device, create
+ * a CAN error skb and post it.
+ *
+ * In some rare cases the devices might get stucked alternating between
+ * CAN_STATE_ERROR_PASSIVE and CAN_STATE_ERROR_WARNING. To prevent
+ * this behavior, we force a bus off state if the device goes in
+ * CAN_STATE_ERROR_WARNING for ES58X_MAX_CONSECUTIVE_WARN consecutive
+ * times with no successful transmission or reception in between.
+ *
+ * Once the device is in bus off state, the only way to restart it is
+ * through the drivers/net/can/dev.c:can_restart() function. The
+ * device is technically capable to recover by itself under certain
+ * circumstances, however, allowing self recovery would create
+ * complex race conditions with drivers/net/can/dev.c:can_restart()
+ * and thus was not implemented. To activate automatic restart, please
+ * set the restart-ms parameter (e.g. ip link set can0 type can
+ * restart-ms 100).
+ *
+ * If the bus is really instable, this function would try to send a
+ * lot of log messages. Those are rate limited (i.e. you will see
+ * messages such as "net_ratelimit: XXX callbacks suppressed" in
+ * dmesg).
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
+             enum es58x_event event, u64 timestamp)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct can_priv *can = netdev_priv(netdev);
+    struct can_device_stats *can_stats = &can->can_stats;
+    struct can_frame *cf;
+    struct sk_buff *skb;
+    unsigned long flags;
+
+    if (!netif_running(netdev)) {
+        if (net_ratelimit())
+            netdev_info(netdev, "%s: %s is down, dropping packet\n",
+                    __func__, netdev->name);
+        netdev->stats.rx_dropped++;
+        return 0;
+    }
+
+    if (error == ES58X_ERR_OK && event == ES58X_EVENT_OK) {
+        netdev_err(netdev, "%s: Both error and event are zero\n",
+               __func__);
+        return -EINVAL;
+    }
+
+    skb = alloc_can_err_skb(netdev, &cf);
+    if (!skb)
+        return -ENOMEM;
+
+    switch (error) {
+    case ES58X_ERR_OK:    /* 0: No error */
+        break;
+
+    case ES58X_ERR_PROT_STUFF:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error BITSUFF\n");
+        cf->data[2] |= CAN_ERR_PROT_STUFF;
+        break;
+
+    case ES58X_ERR_PROT_FORM:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error FORMAT\n");
+        cf->data[2] |= CAN_ERR_PROT_FORM;
+        break;
+
+    case ES58X_ERR_ACK:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error ACK\n");
+        cf->can_id |= CAN_ERR_ACK;
+        break;
+
+    case ES58X_ERR_PROT_BIT:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error BIT\n");
+        cf->data[2] |= CAN_ERR_PROT_BIT;
+        break;
+
+    case ES58X_ERR_PROT_CRC:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error CRC\n");
+        cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
+        break;
+
+    case ES58X_ERR_PROT_BIT1:
+        if (net_ratelimit())
+            netdev_dbg(netdev,
+                   "Error: expected a recessive bit but monitored a
dominant one\n");
+        cf->data[2] |= CAN_ERR_PROT_BIT1;
+        break;
+
+    case ES58X_ERR_PROT_BIT0:
+        if (net_ratelimit())
+            netdev_dbg(netdev,
+                   "Error expected a dominant bit but monitored a
recessive one\n");
+        cf->data[2] |= CAN_ERR_PROT_BIT0;
+        break;
+
+    case ES58X_ERR_PROT_OVERLOAD:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Error OVERLOAD\n");
+        cf->data[2] |= CAN_ERR_PROT_OVERLOAD;
+        break;
+
+    case ES58X_ERR_PROT_UNSPEC:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Unspecified error\n");
+        cf->can_id |= CAN_ERR_PROT;
+        break;
+
+    default:
+        if (net_ratelimit())
+            netdev_err(netdev,
+                   "%s: Unspecified error code 0x%04X\n",
+                   __func__, (int)error);
+        cf->can_id |= CAN_ERR_PROT;
+        break;
+    }
+
+    switch (event) {
+    case ES58X_EVENT_OK:    /* 0: No event */
+        break;
+
+    case ES58X_EVENT_CRTL_ACTIVE:
+        if (can->state == CAN_STATE_BUS_OFF) {
+            netdev_err(netdev,
+                   "%s: state transition: BUS OFF -> ACTIVE\n",
+                   __func__);
+        }
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Event CAN BUS ACTIVE\n");
+        cf->data[1] |= CAN_ERR_CRTL_ACTIVE;
+        can->state = CAN_STATE_ERROR_ACTIVE;
+        break;
+
+    case ES58X_EVENT_CRTL_PASSIVE:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Event CAN BUS PASSIVE\n");
+        /* Either TX or RX error count reached passive state
+         * but we do not know which. Setting both flags by
+         * default.
+         */
+        cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
+        cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
+        if (can->state < CAN_STATE_BUS_OFF)
+            can->state = CAN_STATE_ERROR_PASSIVE;
+        can_stats->error_passive++;
+        if (priv->err_passive_before_rtx_success < U8_MAX)
+            priv->err_passive_before_rtx_success++;
+        break;
+
+    case ES58X_EVENT_CRTL_WARNING:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Event CAN BUS WARNING\n");
+        /* Either TX or RX error count reached warning state
+         * but we do not know which. Setting both flags by
+         * default.
+         */
+        cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
+        cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;
+        if (can->state < CAN_STATE_BUS_OFF)
+            can->state = CAN_STATE_ERROR_WARNING;
+        can_stats->error_warning++;
+        break;
+
+    case ES58X_EVENT_BUSOFF:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "Event CAN BUS OFF\n");
+        /* Prevent the network device queue for being woke-up
+         * by another interrupt while we set the bus to off
+         * status.
+         */
+        spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+        netif_stop_queue(netdev);
+        if (can->state != CAN_STATE_BUS_OFF) {
+            can->state = CAN_STATE_BUS_OFF;
+            can_bus_off(netdev);
+        }
+        spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+        cf->can_id |= CAN_ERR_BUSOFF;
+        can_stats->bus_off++;
+        break;
+
+    case ES58X_EVENT_SINGLE_WIRE:
+        if (net_ratelimit())
+            netdev_warn(netdev,
+                    "Lost connection on either CAN high or CAN low\n");
+        /* Lost connection on either CAN high or CAN
+         * low. Setting both flags by default.
+         */
+        cf->data[4] |= CAN_ERR_TRX_CANH_NO_WIRE;
+        cf->data[4] |= CAN_ERR_TRX_CANL_NO_WIRE;
+        break;
+
+    default:
+        if (net_ratelimit())
+            netdev_err(netdev,
+                   "%s: Unspecified event code 0x%04X\n",
+                   __func__, (int)event);
+        cf->can_id |= CAN_ERR_CRTL;
+        break;
+    }
+
+    if (cf->data[1])
+        cf->can_id |= CAN_ERR_CRTL;
+    if (cf->data[2] || cf->data[3]) {
+        cf->can_id |= CAN_ERR_PROT;
+        can_stats->bus_error++;
+    }
+    if (cf->data[4])
+        cf->can_id |= CAN_ERR_TRX;
+
+    /* driver/net/can/dev.c:can_restart() takes in account error
+     * messages in the RX stats. Doing same here for
+     * consistency.
+     */
+    netdev->stats.rx_packets++;
+    netdev->stats.rx_bytes += cf->can_dlc;
+
+    es58x_set_skb_timestamp(netdev, skb, timestamp);
+    netif_rx(skb);
+
+    if ((event & ES58X_EVENT_CRTL_PASSIVE) &&
+        priv->err_passive_before_rtx_success ==
+        ES58X_CONSECUTIVE_ERR_PASSIVE_MAX) {
+        netdev_info(netdev,
+                "Got %d consecutive warning events with no successful
rx or tx. Forcing bus-off\n",
+                priv->err_passive_before_rtx_success);
+        return es58x_rx_err_msg(netdev, ES58X_ERR_OK,
+                    ES58X_EVENT_BUSOFF, timestamp);
+    }
+
+    return 0;
+}
+
+/* Human readable description of the &enum es58x_cmd_ret_type. */
+static const char *const es58x_cmd_ret_desc[] = {
+    "Set bittiming",
+    "Enable channel",
+    "Disable channel",
+    "Transmit message",
+    "Reset rx",
+    "Reset tx",
+    "Device error"
+};
+
+/**
+ * es58x_rx_dev_ret_u8() - Handle return codes received from the
+ *    ES58X device.
+ * @dev: Device, only used for the dev_XXX() print functions.
+ * @cmd_ret_type: Type of the command which triggered the return code.
+ * @rx_dev_ret_u8: error code as returned by the ES58X device.
+ *
+ * Handles the 8 bits return code. Those are specific to the ES581.4
+ * device. The return value will eventually be used by
+ * es58x_handle_urb_cmd() function which will take proper actions in
+ * case of critical issues such and memory errors or bad CRC values.
+ *
+ * In contrast with es58x_rx_cmd_ret_u32(), the network device is
+ * unknown.
+ *
+ * Return: zero on success, return errno when any error occurs.
+ */
+int es58x_rx_dev_ret_u8(struct device *dev,
+            enum es58x_ret_type cmd_ret_type,
+            enum es58x_ret_u8 rx_dev_ret_u8)
+{
+    const char *ret_desc = es58x_cmd_ret_desc[cmd_ret_type];
+
+    compiletime_assert(ARRAY_SIZE(es58x_cmd_ret_desc) ==
+               ES58X_RET_TYPE_NUM_ENTRIES,
+               "Size mismatch between es58x_cmd_ret_desc and enum
es58x_cmd_ret_type");
+
+    switch (rx_dev_ret_u8) {
+    case ES58X_RET_U8_OK:
+        dev_dbg_ratelimited(dev, "%s: OK\n", ret_desc);
+        break;
+
+    case ES58X_RET_U8_ERR_UNSPECIFIED_FAILURE:
+        dev_err(dev, "%s: unspecified failure\n", ret_desc);
+        break;
+
+    case ES58X_RET_U8_ERR_NO_MEM:
+        dev_err(dev, "%s: device ran out of memory\n", ret_desc);
+        return -ENOMEM;
+
+    case ES58X_RET_U8_ERR_BAD_CRC:
+        dev_err(dev, "%s: CRC of previous command is incorrect\n",
+            ret_desc);
+        return -EIO;
+
+    default:
+        dev_err(dev, "%s: returned unknown value: 0x%02X\n",
+            ret_desc, rx_dev_ret_u8);
+        break;
+    }
+
+    return 0;
+}
+
+/**
+ * es58x_rx_dev_ret_u32() - Handle return codes received from the
+ *    ES58X device.
+ * @netdev: CAN network device.
+ * @cmd_ret_type: Type of the command which triggered the return code.
+ * @rx_cmd_ret_u32: error code as returned by the ES58X device.
+ *
+ * Handles the 32 bits return code. The return value will eventually
+ * be used by es58x_handle_urb_cmd() function which will take proper
+ * actions in case of critical issues such and memory errors or bad
+ * CRC values.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+int es58x_rx_cmd_ret_u32(struct net_device *netdev,
+             enum es58x_ret_type cmd_ret_type,
+             enum es58x_ret_u32 rx_cmd_ret_u32)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    const char *ret_desc = es58x_cmd_ret_desc[cmd_ret_type];
+
+    switch (rx_cmd_ret_u32) {
+    case ES58X_RET_U32_OK:
+        switch (cmd_ret_type) {
+        case ES58X_RET_TYPE_ENABLE_CHANNEL:
+            es58x_flush_pending_tx_msg(netdev);
+            es58x_can_flush_echo_skb(netdev);
+            priv->err_passive_before_rtx_success = 0;
+            priv->can.state = CAN_STATE_ERROR_ACTIVE;
+            es58x_netif_wake_queue(netdev);
+            netdev_info(netdev,
+                    "%s (Serial Number %s): CAN%d channel becomes ready\n",
+                    priv->es58x_dev->udev->product,
+                    priv->es58x_dev->udev->serial,
+                    priv->channel_idx + 1);
+            break;
+
+        case ES58X_RET_TYPE_TX_MSG:
+#ifdef VERBOSE_DEBUG
+            if (net_ratelimit())
+                netdev_vdbg(netdev, "%s: OK\n", ret_desc);
+#endif
+            break;
+
+        default:
+            netdev_dbg(netdev, "%s: OK\n", ret_desc);
+            break;
+        }
+        break;
+
+    case ES58X_RET_U32_ERR_UNSPECIFIED_FAILURE:
+        if (cmd_ret_type == ES58X_RET_TYPE_DISABLE_CHANNEL)
+            netdev_dbg(netdev,
+                   "%s: channel is already closed\n", ret_desc);
+        else
+            netdev_err(netdev,
+                   "%s: unspecified failure\n", ret_desc);
+        break;
+
+    case ES58X_RET_U32_ERR_NO_MEM:
+        netdev_err(netdev, "%s: device ran out of memory\n", ret_desc);
+        return -ENOMEM;
+
+    case ES58X_RET_U32_WARN_PARAM_ADJUSTED:
+        netdev_warn(netdev,
+                "%s: some incompatible parameters have been adjusted\n",
+                ret_desc);
+        break;
+
+    case ES58X_RET_U32_WARN_TX_MAYBE_REORDER:
+        netdev_warn(netdev,
+                "%s: TX messages might have been reordered\n",
+                ret_desc);
+        break;
+
+    case ES58X_RET_U32_ERR_TIMEOUT:
+        netdev_err(netdev, "%s: command timed out\n", ret_desc);
+        break;
+
+    case ES58X_RET_U32_ERR_FIFO_FULL:
+        netdev_warn(netdev, "%s: fifo is full\n", ret_desc);
+        break;
+
+    case ES58X_RET_U32_ERR_BAD_CONFIG:
+        netdev_err(netdev, "%s: bad configuration\n", ret_desc);
+        return -EINVAL;
+
+    case ES58X_RET_U32_ERR_NO_RESOURCE:
+        netdev_err(netdev, "%s: no resource available\n", ret_desc);
+        break;
+
+    default:
+        netdev_err(netdev, "%s returned unknown value: 0x%08X\n",
+               ret_desc, rx_cmd_ret_u32);
+        break;
+    }
+
+    return 0;
+}
+
+/**
+ * es58x_increment_rx_errors() - Increment the network devices' error
+ *    count.
+ * @es58x_dev: ES58X device.
+ *
+ * If an error occurs on the early stages on receiving an URB command,
+ * we might not be able to figure out on which network device the
+ * error occurred. In such case, we arbitrarily increment the error
+ * count of all the network devices attached to our ES58X device.
+ */
+static void es58x_increment_rx_errors(struct es58x_device *es58x_dev)
+{
+    int i;
+
+    for (i = 0; i < es58x_dev->num_can_ch; i++)
+        if (es58x_dev->netdev[i])
+            es58x_dev->netdev[i]->stats.rx_errors++;
+}
+
+/**
+ * es58x_handle_urb_cmd() - Handle the URB command
+ * @es58x_dev: ES58X device.
+ * @urb_cmd: The URB command received from the ES58X device, might not
+ *    be aligned.
+ *
+ * Sends the URB command to the device specific function. Manages the
+ * errors throwed back by those functions.
+ */
+static void es58x_handle_urb_cmd(struct es58x_device *es58x_dev,
+                 const union es58x_urb_cmd *urb_cmd)
+{
+    const struct es58x_operators *ops = es58x_dev->ops;
+    size_t cmd_len;
+    int i, ret;
+
+    ret = ops->handle_urb_cmd(es58x_dev, urb_cmd);
+    switch (ret) {
+    case 0:        /* OK */
+        return;
+
+    case -ENODEV:
+        dev_err_ratelimited(es58x_dev->dev, "Device is not ready\n");
+        break;
+
+    case -EINVAL:
+    case -EMSGSIZE:
+    case -EBADRQC:
+    case -EBADMSG:
+    case -ECHRNG:
+        cmd_len = es58x_get_urb_cmd_len(es58x_dev,
+                        ops->get_msg_len(urb_cmd));
+        dev_err(es58x_dev->dev,
+            "ops->handle_urb_cmd() returned error %pe",
+            ERR_PTR(ret));
+        es58x_print_hex_dump(urb_cmd, cmd_len);
+        break;
+
+    case -EFAULT:
+    case -ENOMEM:
+    case -EIO:
+    default:
+        dev_crit(es58x_dev->dev,
+             "ops->handle_urb_cmd() returned error %pe, detaching all
network devices\n",
+             ERR_PTR(ret));
+        for (i = 0; i < es58x_dev->num_can_ch; i++)
+            if (es58x_dev->netdev[i])
+                netif_device_detach(es58x_dev->netdev[i]);
+        break;
+    }
+
+    /* Because the urb command could not fully be parsed,
+     * channel_id is not confirmed. Incrementing rx_errors count
+     * of all channels.
+     */
+    es58x_increment_rx_errors(es58x_dev);
+}
+
+/**
+ * es58x_check_rx_urb() - Check the length and format of the URB command.
+ * @es58x_dev: ES58X device.
+ * @urb_cmd: The URB command received from the ES58X device, might not
+ *    be aligned.
+ * @urb_actual_len: The actual length of the URB command.
+ *
+ * Check if the first message of the received urb is valid, that is to
+ * say that both the header and the length are coherent.
+ *
+ * Return:
+ * the length of the first message of the URB on success.
+ *
+ * -ENODATA if the URB command is incomplete (in which case, the URB
+ * command should be buffered and combined with the next URB to try to
+ * reconstitute the URB command).
+ *
+ * -EOVERFLOW if the length is bigger than the maximum expected one.
+ *
+ * -EBADRQC if the start of frame does not match the expected value.
+ */
+static signed int es58x_check_rx_urb(struct es58x_device *es58x_dev,
+                     const union es58x_urb_cmd *urb_cmd,
+                     u32 urb_actual_len)
+{
+    const struct device *dev = es58x_dev->dev;
+    const struct es58x_parameters *param = es58x_dev->param;
+    u16 sof, msg_len;
+    signed int urb_cmd_len, ret;
+
+    if (urb_actual_len < param->urb_cmd_header_len) {
+        dev_vdbg(dev,
+             "%s: Received %d bytes [%*ph]: header incomplete\n",
+             __func__, urb_actual_len, urb_actual_len,
+             urb_cmd->raw_cmd);
+        return -ENODATA;
+    }
+
+    sof = get_unaligned_le16(&urb_cmd->sof);
+    if (sof != param->rx_start_of_frame) {
+        dev_err_ratelimited(es58x_dev->dev,
+                    "%s: Expected sequence 0x%04X for start of frame
but got 0x%04X.\n",
+                    __func__, param->rx_start_of_frame, sof);
+        return -EBADRQC;
+    }
+
+    msg_len = es58x_dev->ops->get_msg_len(urb_cmd);
+    urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
+    if (urb_cmd_len > param->rx_urb_cmd_max_len) {
+        dev_err_ratelimited(es58x_dev->dev,
+                    "%s: Biggest expected size for rx urb_cmd is %u
but receive a command of size %d\n",
+                    __func__,
+                    param->rx_urb_cmd_max_len, urb_cmd_len);
+        return -EOVERFLOW;
+    } else if (urb_actual_len < urb_cmd_len) {
+        dev_vdbg(dev, "%s: Received %02d/%02d bytes\n",
+             __func__, urb_actual_len, urb_cmd_len);
+        return -ENODATA;
+    }
+
+    ret = es58x_check_crc(es58x_dev, urb_cmd, urb_cmd_len);
+    if (ret)
+        return ret;
+
+    return urb_cmd_len;
+}
+
+/**
+ * es58x_flush_cmd_buf() - Reset the buffer for URB commands.
+ * @es58x_dev: ES58X device.
+ */
+static void es58x_flush_cmd_buf(struct es58x_device *es58x_dev)
+{
+    memset(&es58x_dev->rx_cmd_buf, 0, es58x_dev->param->rx_urb_cmd_max_len);
+    es58x_dev->rx_cmd_buf_len = 0;
+}
+
+/**
+ * es58x_copy_to_cmd_buf() - Copy an array to the URB command buffer.
+ * @es58x_dev: ES58X device.
+ * @raw_cmd: the buffer we want to copy.
+ * @raw_cmd_len: length of @raw_cmd.
+ *
+ * Concatenates @raw_cmd_len bytes of @raw_cmd to the end of the URB
+ * command buffer.
+ *
+ * Return: zero on success, -EMSGSIZE if not enough space is available
+ * to do the copy.
+ */
+static int es58x_copy_to_cmd_buf(struct es58x_device *es58x_dev,
+                 u8 *raw_cmd, int raw_cmd_len)
+{
+    if (es58x_dev->rx_cmd_buf_len + raw_cmd_len >
+        es58x_dev->param->rx_urb_cmd_max_len)
+        return -EMSGSIZE;
+
+    memcpy(&es58x_dev->rx_cmd_buf.raw_cmd[es58x_dev->rx_cmd_buf_len],
+           raw_cmd, raw_cmd_len);
+    es58x_dev->rx_cmd_buf_len += raw_cmd_len;
+
+    return 0;
+}
+
+/**
+ * es58x_split_urb_try_recovery() - Try to recover bad URB sequences.
+ * @es58x_dev: ES58X device.
+ * @raw_cmd: pointer to the buffer we want to copy.
+ * @raw_cmd_len: length of @raw_cmd.
+ *
+ * Under some rare conditions, we might get incorrect URBs from the
+ * device. From our observations, one of the valid URB gets replaced
+ * by one from the past. The full root cause is not identified.
+ *
+ * This function looks for the next start of frame in the urb buffer
+ * in order to try to recover.
+ *
+ * Such behavior was not observed on the devices of the ES58X FD
+ * family and only seems to impact the ES581.4.
+ *
+ * Return: the number of bytes dropped on success, -EBADMSG if recovery failed.
+ */
+static int es58x_split_urb_try_recovery(struct es58x_device *es58x_dev,
+                    u8 *raw_cmd, size_t raw_cmd_len)
+{
+    union es58x_urb_cmd *urb_cmd;
+    signed int urb_cmd_len;
+    u16 sof;
+    int dropped_bytes = 0;
+
+    es58x_increment_rx_errors(es58x_dev);
+
+    while (raw_cmd_len > sizeof(sof)) {
+        urb_cmd = (union es58x_urb_cmd *)raw_cmd;
+        sof = get_unaligned_le16(&urb_cmd->sof);
+
+        if (sof == es58x_dev->param->rx_start_of_frame) {
+            urb_cmd_len = es58x_check_rx_urb(es58x_dev,
+                             urb_cmd, raw_cmd_len);
+            if ((urb_cmd_len == -ENODATA) || urb_cmd_len > 0) {
+                dev_info_ratelimited(es58x_dev->dev,
+                             "Recovery successful! Dropped %d bytes
(urb_cmd_len: %d)\n",
+                             dropped_bytes,
+                             urb_cmd_len);
+                return dropped_bytes;
+            }
+        }
+        raw_cmd++;
+        raw_cmd_len--;
+        dropped_bytes++;
+    }
+
+    dev_warn_ratelimited(es58x_dev->dev, "%s: Recovery failed\n", __func__);
+    return -EBADMSG;
+}
+
+/**
+ * es58x_handle_incomplete_cmd() - Reconstitute an URB command from
+ *    different URB pieces.
+ * @es58x_dev: ES58X device.
+ * @urb: last urb buffer received.
+ *
+ * The device might split the URB commands in an arbitrary amount of
+ * pieces. This function concatenates those in an URB buffer until a
+ * full URB command is reconstituted and consume it.
+ *
+ * Return:
+ * number of bytes consumed from @urb if successful.
+ *
+ * -ENODATA if the URB command is still incomplete.
+ *
+ * -EBADMSG if the URB command is incorrect.
+ */
+static signed int es58x_handle_incomplete_cmd(struct es58x_device *es58x_dev,
+                          struct urb *urb)
+{
+    size_t cpy_len;
+    signed int urb_cmd_len, tmp_cmd_buf_len, ret;
+
+    tmp_cmd_buf_len = es58x_dev->rx_cmd_buf_len;
+    cpy_len = min_t(int, es58x_dev->param->rx_urb_cmd_max_len -
+            es58x_dev->rx_cmd_buf_len, urb->actual_length);
+    ret = es58x_copy_to_cmd_buf(es58x_dev, urb->transfer_buffer, cpy_len);
+    if (ret < 0)
+        return ret;
+
+    urb_cmd_len = es58x_check_rx_urb(es58x_dev, &es58x_dev->rx_cmd_buf,
+                     es58x_dev->rx_cmd_buf_len);
+    if (urb_cmd_len == -ENODATA) {
+        return -ENODATA;
+    } else if (urb_cmd_len < 0) {
+        dev_err_ratelimited(es58x_dev->dev,
+                    "Could not reconstitute incomplete command from
previous URB, dropping %d bytes\n",
+                    tmp_cmd_buf_len + urb->actual_length);
+        dev_err_ratelimited(es58x_dev->dev,
+                    "Error code: %pe, es58x_dev->rx_cmd_buf_len: %d,
urb->actual_length: %u\n",
+                    ERR_PTR(urb_cmd_len),
+                    tmp_cmd_buf_len, urb->actual_length);
+        es58x_print_hex_dump(&es58x_dev->rx_cmd_buf, tmp_cmd_buf_len);
+        es58x_print_hex_dump(urb->transfer_buffer, urb->actual_length);
+        return urb->actual_length;
+    }
+
+    es58x_handle_urb_cmd(es58x_dev, &es58x_dev->rx_cmd_buf);
+    return urb_cmd_len - tmp_cmd_buf_len;    /* consumed length */
+}
+
+/**
+ * es58x_split_urb() - Cut the received URB in individual URB commands.
+ * @es58x_dev: ES58X device.
+ * @urb: last urb buffer received.
+ *
+ * The device might send urb in bulk format (i.e. several URB commands
+ * concatenated together). This function will split all the commands
+ * contained in the urb.
+ *
+ * Return:
+ * number of bytes consumed from @urb if successful.
+ *
+ * -ENODATA if the URB command is still incomplete.
+ *
+ * -EBADMSG if the URB command is incorrect.
+ */
+static signed int es58x_split_urb(struct es58x_device *es58x_dev,
+                  struct urb *urb)
+{
+    const u8 es58x_is_alive = 0x11;
+    union es58x_urb_cmd *urb_cmd;
+    u8 *raw_cmd = urb->transfer_buffer;
+    ssize_t raw_cmd_len = urb->actual_length;
+    int ret;
+
+    if (es58x_dev->rx_cmd_buf_len != 0) {
+        ret = es58x_handle_incomplete_cmd(es58x_dev, urb);
+        if (ret != -ENODATA)
+            es58x_flush_cmd_buf(es58x_dev);
+        if (ret < 0)
+            return ret;
+
+        raw_cmd += ret;
+        raw_cmd_len -= ret;
+    }
+
+    while (raw_cmd_len > 0) {
+        if (raw_cmd[0] == es58x_is_alive) {
+            raw_cmd++;
+            raw_cmd_len--;
+            continue;
+        }
+        urb_cmd = (union es58x_urb_cmd *)raw_cmd;
+        ret = es58x_check_rx_urb(es58x_dev, urb_cmd, raw_cmd_len);
+        if (ret > 0) {
+            es58x_handle_urb_cmd(es58x_dev, urb_cmd);
+        } else if (ret == -ENODATA) {
+            es58x_copy_to_cmd_buf(es58x_dev, raw_cmd, raw_cmd_len);
+            return -ENODATA;
+        } else if (ret < 0) {
+            ret = es58x_split_urb_try_recovery(es58x_dev, raw_cmd,
+                               raw_cmd_len);
+            if (ret < 0)
+                return ret;
+        }
+        raw_cmd += ret;
+        raw_cmd_len -= ret;
+    }
+
+    return 0;
+}
+
+/**
+ * es58x_read_bulk_callback() - Callback for reading data from device.
+ * @urb: last urb buffer received.
+ *
+ * This function gets eventually called each time an URB is received
+ * from the ES58X device.
+ *
+ * Checks urb status, calls read function and resubmits urb read
+ * operation.
+ */
+static void es58x_read_bulk_callback(struct urb *urb)
+{
+    struct es58x_device *es58x_dev = urb->context;
+    const struct device *dev = es58x_dev->dev;
+    int i, ret;
+
+    switch (urb->status) {
+    case 0:        /* success */
+        break;
+
+    case -EOVERFLOW:
+        dev_err_ratelimited(dev, "%s: error %pe\n",
+                    __func__, ERR_PTR(urb->status));
+        es58x_print_hex_dump_debug(urb->transfer_buffer,
+                       urb->transfer_buffer_length);
+        goto resubmit_urb;
+
+    case -EPROTO:
+        dev_warn_ratelimited(dev, "%s: error %pe. Device unplugged?\n",
+                     __func__, ERR_PTR(urb->status));
+        goto free_urb;
+
+    case -ENOENT:
+    case -EPIPE:
+        dev_err_ratelimited(dev, "%s: error %pe\n",
+                    __func__, ERR_PTR(urb->status));
+        goto free_urb;
+
+    case -ESHUTDOWN:
+        dev_dbg_ratelimited(dev, "%s: error %pe\n",
+                    __func__, ERR_PTR(urb->status));
+        goto free_urb;
+
+    default:
+        dev_err_ratelimited(dev, "%s: error %pe\n",
+                    __func__, ERR_PTR(urb->status));
+        goto resubmit_urb;
+    }
+
+    ret = es58x_split_urb(es58x_dev, urb);
+    if ((ret != -ENODATA) && ret < 0) {
+        dev_err(es58x_dev->dev, "es58x_split_urb() returned error %pe",
+            ERR_PTR(ret));
+        es58x_print_hex_dump_debug(urb->transfer_buffer,
+                       urb->actual_length);
+
+        /* Because the urb command could not be parsed,
+         * channel_id is not confirmed. Incrementing rx_errors
+         * count of all channels.
+         */
+        es58x_increment_rx_errors(es58x_dev);
+    }
+
+ resubmit_urb:
+    usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->rx_pipe,
+              urb->transfer_buffer, urb->transfer_buffer_length,
+              es58x_read_bulk_callback, es58x_dev);
+
+    ret = usb_submit_urb(urb, GFP_ATOMIC);
+    if (ret == -ENODEV) {
+        for (i = 0; i < es58x_dev->num_can_ch; i++)
+            if (es58x_dev->netdev[i])
+                netif_device_detach(es58x_dev->netdev[i]);
+    } else if (ret)
+        dev_err_ratelimited(dev,
+                    "Failed resubmitting read bulk urb: %pe\n",
+                    ERR_PTR(ret));
+    return;
+
+ free_urb:
+    usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+              urb->transfer_buffer, urb->transfer_dma);
+}
+
+/**
+ * es58x_write_bulk_callback() - Callback after writing data to the device.
+ * @urb: urb buffer which was previously submitted.
+ *
+ * This function gets eventually called each time an URB was sent to
+ * the ES58X device.
+ *
+ * Puts the @urb back to the urbs idle anchor and tries to restart the
+ * network queue.
+ */
+static void es58x_write_bulk_callback(struct urb *urb)
+{
+    struct net_device *netdev = urb->context;
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+
+    switch (urb->status) {
+    case 0:        /* success */
+        break;
+
+    case -EOVERFLOW:
+        if (net_ratelimit())
+            netdev_err(netdev, "%s: error %pe\n",
+                   __func__, ERR_PTR(urb->status));
+        es58x_print_hex_dump(urb->transfer_buffer,
+                     urb->transfer_buffer_length);
+        break;
+
+    case -ENOENT:
+        if (net_ratelimit())
+            netdev_dbg(netdev, "%s: error %pe\n",
+                   __func__, ERR_PTR(urb->status));
+        usb_free_coherent(urb->dev,
+                  es58x_dev->param->tx_urb_cmd_max_len,
+                  urb->transfer_buffer, urb->transfer_dma);
+        return;
+
+    default:
+        if (net_ratelimit())
+            netdev_info(netdev, "%s: error %pe\n",
+                    __func__, ERR_PTR(urb->status));
+        break;
+    }
+
+    usb_anchor_urb(urb, &es58x_dev->tx_urbs_idle);
+    /* Wake the queue if it was stopped because of exhaustion of
+     * urb resources.
+     */
+    if (atomic_inc_return(&es58x_dev->tx_urbs_idle_cnt) ==
+        es58x_dev->num_can_ch)
+        es58x_netif_wake_all_queues(es58x_dev);
+}
+
+/**
+ * es58x_alloc_urb() - Allocate memory for an URB and its transfer
+ *    buffer.
+ * @es58x_dev: ES58X device.
+ * @urb: URB to be allocated.
+ * @buf: used to return DMA address of buffer.
+ * @buf_len: requested buffer size.
+ * @mem_flags: affect whether allocation may block.
+ *
+ * Allocates an URB and its @transfer_buffer and set its @transfer_dma
+ * address.
+ *
+ * This function is used at start-up to allocate all of our TX and RX
+ * URBs at once (in order to avoid numerous memory allocations during
+ * run time) and might be used during run time under extremely rare
+ * conditions by @es58x_get_tx_urb() (c.f. comments of this function).
+ *
+ * Return: zero on success, -ENOMEM if no memory is available.
+ */
+static int es58x_alloc_urb(struct es58x_device *es58x_dev, struct urb **urb,
+               u8 **buf, size_t buf_len, gfp_t mem_flags)
+{
+    *urb = usb_alloc_urb(0, mem_flags);
+    if (!*urb) {
+        dev_err(es58x_dev->dev, "No memory left for URBs\n");
+        return -ENOMEM;
+    }
+
+    *buf = usb_alloc_coherent(es58x_dev->udev, buf_len,
+                  mem_flags, &(*urb)->transfer_dma);
+    if (!*buf) {
+        dev_err(es58x_dev->dev, "No memory left for USB buffer\n");
+        usb_free_urb(*urb);
+        return -ENOMEM;
+    }
+
+    (*urb)->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+    return 0;
+}
+
+/**
+ * es58x_get_tx_urb() - Get an URB for transmission.
+ * @netdev: CAN network device.
+ *
+ * Gets an URB from the idle urbs anchor and stop all network devices'
+ * queue if the idle urbs anchor is nearly empty.
+ *
+ * If the URB anchor is empty, allocates an new URB.
+ *
+ * Under normal circumstances, the network device stop/wake
+ * management should prevent any further request for memory
+ * allocations to occur when trying to send a message.
+ *
+ * Yet, new URB memory allocation might occur after a restart from bus
+ * off status when @es58x_set_mode() tries to disable and re-enable
+ * the device. This would only occur if no idle URBs are available at
+ * the moment (which is highly improbable because
+ * @es58x_write_bulk_callback() should have returned the URBs to the
+ * idle urbs anchor by that point).
+ *
+ * Return: a pointer to an URB on success, NULL if no memory is
+ * available.
+ */
+static struct urb *es58x_get_tx_urb(struct net_device *netdev)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    struct urb *urb;
+    unsigned long flags;
+    int ret;
+
+    urb = usb_get_from_anchor(&es58x_dev->tx_urbs_idle);
+
+    if (!urb) {
+        size_t tx_buf_len;
+        u8 *buf;
+
+        netdev_warn(netdev,
+                "%s: Idle TX URB anchor is empty. Allocating an extra URB\n",
+                __func__);
+        tx_buf_len = es58x_dev->param->tx_urb_cmd_max_len;
+        ret = es58x_alloc_urb(es58x_dev, &urb, &buf, tx_buf_len,
+                      GFP_ATOMIC);
+        if (ret)
+            urb = NULL;
+        else
+            usb_fill_bulk_urb(urb, es58x_dev->udev,
+                      es58x_dev->tx_pipe, buf, tx_buf_len,
+                      NULL, NULL);
+    } else {
+        spin_lock_irqsave(&es58x_dev->tx_urbs_idle.lock, flags);
+        if (atomic_dec_return(&es58x_dev->tx_urbs_idle_cnt) <
+            es58x_dev->num_can_ch)
+            es58x_netif_stop_all_queues(es58x_dev);
+        spin_unlock_irqrestore(&es58x_dev->tx_urbs_idle.lock, flags);
+    }
+
+    return urb;
+}
+
+/**
+ * es58x_submit_urb() - Send data to the device.
+ * @es58x_dev: ES58X device.
+ * @urb: URB to be sent.
+ * @netdev: CAN network device.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_submit_urb(struct es58x_device *es58x_dev, struct urb *urb,
+                struct net_device *netdev)
+{
+    int ret;
+
+    es58x_set_crc(urb->transfer_buffer, urb->transfer_buffer_length);
+    usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->tx_pipe,
+              urb->transfer_buffer, urb->transfer_buffer_length,
+              es58x_write_bulk_callback, netdev);
+    usb_anchor_urb(urb, &es58x_dev->tx_urbs_busy);
+    ret = usb_submit_urb(urb, GFP_ATOMIC);
+    if (ret) {
+        netdev_err(netdev, "%s: USB send urb failure: %pe\n",
+               __func__, ERR_PTR(ret));
+        usb_unanchor_urb(urb);
+        usb_free_coherent(urb->dev,
+                  es58x_dev->param->tx_urb_cmd_max_len,
+                  urb->transfer_buffer, urb->transfer_dma);
+    }
+    usb_free_urb(urb);
+
+    return ret;
+}
+
+/**
+ * es58x_send_msg() - Prepare an URB and submit it.
+ * @es58x_dev: ES58X device.
+ * @cmd_type: Command type.
+ * @cmd_id: Command ID.
+ * @msg: ES58X message to be sent.
+ * @msg_len: Length of @msg.
+ * @channel_idx: Index of the network device.
+ *
+ * Creates an URB command from a given message, sets the header and the
+ * CRC and then submits it.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+int es58x_send_msg(struct es58x_device *es58x_dev, u8 cmd_type, u8 cmd_id,
+           const void *msg, u16 msg_len, int channel_idx)
+{
+    struct net_device *netdev;
+    union es58x_urb_cmd *urb_cmd;
+    struct urb *urb;
+    int urb_cmd_len;
+
+    if (channel_idx == ES58X_CHANNEL_IDX_NA)
+        netdev = es58x_dev->netdev[0];    /* Default to first channel */
+    else
+        netdev = es58x_dev->netdev[channel_idx];
+
+    urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
+    if (urb_cmd_len > es58x_dev->param->tx_urb_cmd_max_len)
+        return -EOVERFLOW;
+
+    urb = es58x_get_tx_urb(netdev);
+    if (!urb)
+        return -EBUSY;
+
+    urb_cmd = urb->transfer_buffer;
+    es58x_dev->ops->fill_urb_header(urb_cmd, cmd_type, cmd_id,
+                    channel_idx, msg_len);
+    memcpy(&urb_cmd->raw_cmd[es58x_dev->param->urb_cmd_header_len],
+           msg, msg_len);
+    urb->transfer_buffer_length = urb_cmd_len;
+
+    return es58x_submit_urb(es58x_dev, urb, netdev);
+}
+
+/**
+ * es58x_start() - Start USB device.
+ * @es58x_dev: ES58X device.
+ *
+ * Allocate URBs for transmission and reception and put them in their
+ * respective anchors.
+ *
+ * This function took a lot of inspiration from the other drivers in
+ * drivers/net/can/usb.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_start(struct es58x_device *es58x_dev)
+{
+    const struct device *dev = es58x_dev->dev;
+    const struct es58x_parameters *param = es58x_dev->param;
+    size_t rx_buf_len, tx_buf_len;
+    struct urb *urb;
+    u8 *buf;
+    int i;
+    int ret = -EINVAL;
+
+    rx_buf_len = es58x_dev->rx_max_packet_size;
+    dev_dbg(dev, "%s: Allocation %d rx URBs each of size %zu\n", __func__,
+        param->rx_urb_max, rx_buf_len);
+
+    for (i = 0; i < param->rx_urb_max; i++) {
+        ret = es58x_alloc_urb(es58x_dev, &urb, &buf, rx_buf_len,
+                      GFP_KERNEL);
+        if (ret)
+            break;
+
+        usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->rx_pipe,
+                  buf, rx_buf_len, es58x_read_bulk_callback,
+                  es58x_dev);
+        usb_anchor_urb(urb, &es58x_dev->rx_urbs);
+
+        ret = usb_submit_urb(urb, GFP_KERNEL);
+        if (ret) {
+            usb_unanchor_urb(urb);
+            usb_free_coherent(es58x_dev->udev, rx_buf_len,
+                      buf, urb->transfer_dma);
+            usb_free_urb(urb);
+            break;
+        }
+        usb_free_urb(urb);
+    }
+
+    if (i == 0) {
+        dev_err(dev, "%s: Could not setup any rx URBs\n", __func__);
+        return ret;
+    } else if (i < param->rx_urb_max) {
+        dev_warn(dev,
+             "%s: Could only allocate %d on %d URBs. Rx performance
may be slow\n",
+             __func__, i, param->rx_urb_max);
+    }
+
+    tx_buf_len = es58x_dev->param->tx_urb_cmd_max_len;
+    dev_dbg(dev, "%s: Allocation %d tx URBs each of size %zu\n", __func__,
+        param->tx_urb_max, tx_buf_len);
+
+    for (i = 0; i < param->tx_urb_max; i++) {
+        ret = es58x_alloc_urb(es58x_dev, &urb, &buf, tx_buf_len,
+                      GFP_KERNEL);
+        if (ret)
+            break;
+
+        usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->tx_pipe,
+                  buf, tx_buf_len, NULL, NULL);
+        usb_anchor_urb(urb, &es58x_dev->tx_urbs_idle);
+        usb_free_urb(urb);
+    }
+
+    if (i == 0) {
+        dev_err(dev, "%s: Could not setup any tx URBs\n", __func__);
+        return ret;
+    } else if (i < param->tx_urb_max) {
+        dev_warn(dev,
+             "%s: Could only allocate %d on %d URBs. Tx performance
may be slow\n",
+             __func__, i, param->tx_urb_max);
+    }
+    atomic_set(&es58x_dev->tx_urbs_idle_cnt, i);
+
+    return ret;
+}
+
+/**
+ * es58x_enable_channel() - Enable the network device.
+ * @netdev: CAN network device.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_enable_channel(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    int ret;
+
+    ret = es58x_dev->ops->enable_channel(es58x_dev, priv->channel_idx);
+    if (ret)
+        netdev_err(netdev, "%s: Could not enable the channel: %pe\n",
+               __func__, ERR_PTR(ret));
+
+    return ret;
+}
+
+/**
+ * es58x_open() - Open and start network device.
+ * @netdev: CAN network device.
+ *
+ * Called when the network transitions to the up state.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_open(struct net_device *netdev)
+{
+    int ret;
+
+    ret = open_candev(netdev);
+    if (ret)
+        return ret;
+
+    ret = es58x_enable_channel(netdev);
+    if (ret)
+        return ret;
+
+    netif_start_queue(netdev);
+
+    return ret;
+}
+
+/**
+ * es58x_stop() - Disable the network device.
+ * @netdev: CAN network device.
+ *
+ * Called when the network transitions to the down state.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_stop(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    unsigned long flags;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    netif_stop_queue(netdev);
+    priv->can.state = CAN_STATE_STOPPED;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+    es58x_can_flush_echo_skb(netdev);
+    close_candev(netdev);
+
+    es58x_flush_pending_tx_msg(netdev);
+
+    return 0;
+}
+
+/**
+ * es58x_xmit_commit() - Send the bulk urb.
+ * @netdev: CAN network device.
+ *
+ * Update the loopback FIFO and do a bulk send.
+ *
+ * Each loopback skb should be put individually with
+ * can_put_echo_skb(). This function should be called only once by
+ * bulk transmission.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_xmit_commit(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    unsigned long flags;
+    unsigned int pkts = priv->tx_can_msg_cnt;
+    int ret;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    if (!es58x_is_can_state_active(netdev)) {
+        netdev_warn(netdev,
+                "%s: Device turned to CAN state: %d while preparing
to send. Aborting transmission\n",
+                __func__, priv->can.state);
+        spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+        return -ENETDOWN;
+    }
+    priv->num_echo_skb += pkts;
+    priv->current_packet_idx += pkts;
+    es58x_add_skb_idx(priv, &priv->echo_skb_head_idx, pkts);
+    if (priv->num_echo_skb >= es58x_echo_skb_stop_threshold(priv))
+        netif_stop_queue(netdev);
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    ret = es58x_submit_urb(priv->es58x_dev, priv->tx_urb, netdev);
+    if (ret) {
+        netdev_warn(netdev,
+                "%s: es58x_submit_urb returned failed: %pe
priv->num_echo_skb = %u\n",
+                __func__, ERR_PTR(ret), priv->num_echo_skb);
+        spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+        priv->num_echo_skb -= pkts;
+        priv->current_packet_idx -= pkts;
+        es58x_add_skb_idx(priv, &priv->echo_skb_head_idx,
+                  priv->can.echo_skb_max - pkts);
+        spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+    }
+    priv->tx_urb = NULL;
+
+    return ret;
+}
+
+/**
+ * es58x_start_xmit() - Transmit an skb.
+ * @skb: socket buffer of a CAN message.
+ * @netdev: CAN network device.
+ *
+ * Called when a packet needs to be transmitted.
+ *
+ * This function relies on Byte Queue Limits (BQL). The main benefit
+ * it to increase the throughput by allowing bulk transfers
+ * (c.f. xmit_more flag).
+ *
+ * Queues up to tx_bulk_max messages in &tx_urb buffer and does
+ * a bulk send of all messages in one single URB.
+ *
+ * Return:
+ * NETDEV_TX_OK if we could manage the @skb (either transmit it or
+ * drop it)
+ *
+ * NETDEV_TX_BUSY if the device is busy (this is a bug, the network
+ * device stop/wake management should prevent this return code to
+ * occur).
+ */
+static netdev_tx_t es58x_start_xmit(struct sk_buff *skb,
+                    struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    unsigned int packet_idx, tx_msg_threshold;
+    u16 skb_idx;
+    u8 channel_idx = priv->channel_idx;
+    bool send_doorbell;
+    int ret;
+
+    if (((struct can_frame *)skb->data)->can_id & CAN_ERR_FLAG) {
+        netdev_info(netdev,
+                "%s: CAN_ERR_FLAG is set but device does not support
sending error frames. Dropping message\n",
+                __func__);
+        if (priv->tx_urb && !netdev_xmit_more()) {
+            __netdev_sent_queue(netdev, 0, false);
+            ret = es58x_xmit_commit(netdev);
+            if (ret)
+                goto xmit_failure;
+        }
+        return NETDEV_TX_OK;
+    }
+
+    if (!priv->tx_urb) {
+        priv->tx_urb = es58x_get_tx_urb(netdev);
+        if (!priv->tx_urb)
+            return NETDEV_TX_BUSY;
+        memset(priv->tx_urb->transfer_buffer, 0,
+               es58x_dev->param->tx_urb_cmd_max_len);
+        priv->tx_urb->transfer_buffer_length =
+            es58x_dev->param->urb_cmd_header_len;
+        priv->tx_can_msg_cnt = 0;
+        priv->tx_can_msg_is_fd = can_is_canfd_skb(skb);
+    } else if (priv->tx_can_msg_is_fd != can_is_canfd_skb(skb)) {
+        /* Can not send bulk message with mixed CAN and CAN-FD
+         * frames.
+         */
+        __netdev_sent_queue(netdev, 0, false);
+        ret = es58x_xmit_commit(netdev);
+        if (ret)
+            goto xmit_failure;
+        return es58x_start_xmit(skb, netdev);
+    }
+
+    packet_idx = priv->current_packet_idx + priv->tx_can_msg_cnt;
+    ret = es58x_dev->ops->tx_can_msg(priv, channel_idx,
+                     packet_idx, skb,
+                     priv->tx_urb->transfer_buffer,
+                     &priv->tx_urb->transfer_buffer_length);
+    if (ret)
+        goto xmit_failure;
+
+    skb_idx = priv->echo_skb_head_idx;
+    es58x_add_skb_idx(priv, &skb_idx, priv->tx_can_msg_cnt);
+    skb_tx_timestamp(skb);
+    ret = can_put_echo_skb(skb, netdev, skb_idx);
+    if (ret)
+        goto xmit_failure;
+    priv->tx_can_msg_cnt++;
+
+    send_doorbell = __netdev_sent_queue(netdev, es58x_can_frame_bytes(skb),
+                        netdev_xmit_more());
+    tx_msg_threshold = min_t(unsigned int,
+                 es58x_dev->param->tx_bulk_max,
+                 priv->can.echo_skb_max - priv->num_echo_skb);
+    if (send_doorbell || priv->tx_can_msg_cnt >= tx_msg_threshold) {
+        ret = es58x_xmit_commit(netdev);
+        if (ret)
+            goto xmit_failure;
+    }
+
+    return NETDEV_TX_OK;
+
+ xmit_failure:
+    netdev->stats.tx_errors++;
+    es58x_flush_pending_tx_msg(netdev);
+    netdev_err(netdev, "%s: send message failure: %pe\n",
+           __func__, ERR_PTR(ret));
+    return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops es58x_netdev_ops = {
+    .ndo_open = es58x_open,
+    .ndo_stop = es58x_stop,
+    .ndo_start_xmit = es58x_start_xmit
+};
+
+/**
+ * es58x_set_bittiming() - Configure all the nominal bit timing
+ *    parameters.
+ * @netdev: CAN network device.
+ *
+ * Only relevant for ES581.4 (the ES58X FD family sets the bittiming
+ * parameters at the same time as the channel gets enabled).
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_set_bittiming(struct net_device *netdev)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    int ret;
+
+    /* Make sure that channel is closed before sending configuration. */
+    ret = es58x_dev->ops->disable_channel(es58x_dev, priv->channel_idx);
+    if (ret)
+        netdev_err(netdev, "%s: Could not disable the channel: %pe\n",
+               __func__, ERR_PTR(ret));
+    ret = es58x_dev->ops->set_bittiming(es58x_dev, priv->channel_idx);
+    if (ret)
+        netdev_err(netdev, "%s: Could not set bittiming: %pe\n",
+               __func__, ERR_PTR(ret));
+
+    return ret;
+}
+
+/**
+ * es58x_set_data_bittiming() - Configure all the data bit timing parameters.
+ * @netdev: CAN network device.
+ *
+ * Dummy function: ES58X FD family sets the bittiming
+ * parameters at the same time as the channel gets enabled.
+ *
+ * Return: zero.
+ */
+static int es58x_set_data_bittiming(struct net_device *netdev)
+{
+    return 0;
+}
+
+/**
+ * es58x_reset() - Reset one channel of the device.
+ * @netdev: CAN network device.
+ *
+ * Race conditions might appear when trying to use the reset_rx()
+ * and reset_tx() methods (e.g. loopback packets might remain in the
+ * queue causing some use after free issues in
+ * es58x_can_get_echo_skb()). Disabling and reenabling the channel is
+ * safer.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_reset(struct net_device *netdev)
+{
+    int ret = 0;
+
+    if (es58x_is_can_state_active(netdev))
+        es58x_priv(netdev)->can.do_set_mode(netdev, CAN_MODE_STOP);
+    WARN_ON(!netif_queue_stopped(netdev));
+
+    ret = es58x_set_bittiming(netdev);
+    if (ret)
+        goto failure;
+    ret = es58x_enable_channel(netdev);
+    if (ret)
+        goto failure;
+
+    return ret;
+
+ failure:
+    netdev_err(netdev, "%s: reset failure: %pe\n", __func__, ERR_PTR(ret));
+    return ret;
+}
+
+/**
+ * es58x_set_mode() - Change network device mode.
+ * @netdev: CAN network device.
+ * @mode: either %CAN_MODE_START, %CAN_MODE_STOP or %CAN_MODE_SLEEP
+ *
+ * This function is used by drivers/net/can/dev.c:can_restart() to
+ * recover from a bus off state. Thus only the only value expected for
+ * @mode is %CAN_MODE_START. None the less, other modes were
+ * implemented as well.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct can_priv *can = netdev_priv(netdev);
+    unsigned long flags;
+
+    netdev_dbg(netdev, "%s: Switching to can_mode %d\n", __func__, mode);
+
+    switch (mode) {
+    case CAN_MODE_START:
+        switch (can->state) {
+        case CAN_STATE_BUS_OFF:
+            return es58x_reset(netdev);
+
+        case CAN_STATE_STOPPED:
+        case CAN_STATE_SLEEPING:
+            es58x_netif_wake_queue(netdev);
+            can->state = CAN_STATE_ERROR_ACTIVE;
+            return 0;
+
+        case CAN_STATE_ERROR_ACTIVE:
+        case CAN_STATE_ERROR_WARNING:
+        case CAN_STATE_ERROR_PASSIVE:
+        default:
+            return 0;
+        }
+
+    case CAN_MODE_STOP:
+    case CAN_MODE_SLEEP:
+        spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+        netif_stop_queue(netdev);
+        can->state = (mode == CAN_MODE_STOP) ?
+            CAN_STATE_STOPPED : CAN_STATE_SLEEPING;
+        spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+        return 0;
+
+    default:
+        netdev_err(netdev, "%s: Invalid can_mode value: %d\n",
+               __func__, mode);
+        return -EOPNOTSUPP;
+    }
+}
+
+/**
+ * es58x_init_priv() - Initialize private parameters.
+ * @es58x_dev: ES58X device.
+ * @priv: ES58X private parameters related to the network device.
+ * @channel_idx: Index of the network device.
+ */
+static void es58x_init_priv(struct es58x_device *es58x_dev,
+                struct es58x_priv *priv, int channel_idx)
+{
+    const struct es58x_parameters *param = es58x_dev->param;
+    struct can_priv *can = &priv->can;
+
+    priv->es58x_dev = es58x_dev;
+    priv->channel_idx = channel_idx;
+    priv->tx_urb = NULL;
+    priv->tx_can_msg_cnt = 0;
+    spin_lock_init(&priv->echo_skb_spinlock);
+
+    can->bittiming_const = param->bittiming_const;
+    can->do_set_bittiming = es58x_set_bittiming;
+    if (param->ctrlmode_supported & CAN_CTRLMODE_FD) {
+        can->data_bittiming_const = param->data_bittiming_const;
+        can->do_set_data_bittiming = es58x_set_data_bittiming;
+    }
+    can->bitrate_max = param->bitrate_max;
+    can->clock = param->clock;
+
+    can->state = CAN_STATE_STOPPED;
+
+    /* Hardware loopback is always enabled, regardless of the
+     * value of can.ctrlmode & CAN_CTRLMODE_LOOPBACK.
+     */
+    can->ctrlmode_supported = param->ctrlmode_supported;
+    can->do_get_berr_counter = NULL;    /* Not supported */
+
+    can->do_set_mode = es58x_set_mode;
+}
+
+/**
+ * es58x_init_netdev() - Initialize the network device.
+ * @es58x_dev: ES58X device.
+ * @channel_idx: Index of the network device.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_init_netdev(struct es58x_device *es58x_dev, int channel_idx)
+{
+    struct net_device *netdev;
+    struct device *dev = es58x_dev->dev;
+    int ret;
+
+    netdev = alloc_candev(sizeof(struct es58x_priv),
+                  es58x_dev->param->echo_skb_max);
+    if (!netdev) {
+        dev_err(dev, "Could not allocate candev\n");
+        return -ENOMEM;
+    }
+    SET_NETDEV_DEV(netdev, dev);
+    es58x_dev->netdev[channel_idx] = netdev;
+    es58x_init_priv(es58x_dev, es58x_priv(netdev), channel_idx);
+
+    netdev->netdev_ops = &es58x_netdev_ops;
+    netdev->flags |= IFF_ECHO;    /* we support local echo */
+
+    ret = register_candev(netdev);
+    if (ret)
+        return ret;
+    netdev_dbg(netdev, "%s: Registered channel %s\n",
+           es58x_dev->udev->product, netdev->name);
+
+#ifdef CONFIG_BQL
+    netdev_get_tx_queue(netdev, 0)->dql.min_limit =
+        es58x_dev->param->dql_limit_min;
+#endif
+
+    return ret;
+}
+
+/**
+ * es58x_get_product_info() - Get the product information and print them.
+ * @es58x_dev: ES58X device.
+ *
+ * Do a synchronous call to get the product information.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_get_product_info(struct es58x_device *es58x_dev)
+{
+    struct usb_device *udev = es58x_dev->udev;
+    const int es58x_prod_info_idx = 6;
+    /* Empirical tests show a prod_info length of maximum 83,
+     * below should be more than enough.
+     */
+    const size_t prod_info_len = 127;
+    char *prod_info;
+    int ret;
+
+    prod_info = kmalloc(prod_info_len, GFP_KERNEL);
+    if (!prod_info)
+        return -ENOMEM;
+
+    ret = usb_string(udev, es58x_prod_info_idx, prod_info, prod_info_len);
+    if (ret < 0) {
+        dev_err(es58x_dev->dev,
+            "%s: Could not read the product info: %pe\n",
+            __func__, ERR_PTR(ret));
+        return ret;
+    } else if (ret >= prod_info_len - 1) {
+        dev_warn(es58x_dev->dev,
+             "%s: Buffer is too small, result might be truncated\n",
+             __func__);
+    }
+    dev_info(es58x_dev->dev, "Product info: %s\n", prod_info);
+    kfree(prod_info);
+
+    return 0;
+}
+
+/**
+ * es58x_init_es58x_dev() - Initialize the ES58X device.
+ * @intf: USB interface
+ * @p_es58x_dev: pointer to the address of the ES58X device.
+ *
+ * Return: zero on success, errno when any error occurs.
+ */
+static int es58x_init_es58x_dev(struct usb_interface *intf,
+                struct es58x_device **p_es58x_dev)
+{
+    struct device *dev = &intf->dev;
+    struct es58x_device *es58x_dev;
+    const struct es58x_parameters *param;
+    const struct es58x_operators *ops;
+    struct usb_device *udev = interface_to_usbdev(intf);
+    struct usb_endpoint_descriptor *ep_in, *ep_out;
+    const u16 usb_id_product = le16_to_cpu(udev->descriptor.idProduct);
+    u8 num_can_ch;
+    int ret;
+
+    dev_info(dev,
+         "Starting %s %s (Serial Number %s) driver version %s\n",
+         udev->manufacturer, udev->product, udev->serial, DRV_VERSION);
+
+    ret = usb_find_common_endpoints(intf->cur_altsetting, &ep_in, &ep_out,
+                    NULL, NULL);
+    if (ret)
+        return ret;
+
+    switch (usb_id_product) {
+    case ES581_4_PRODUCT_ID:    /* 2 Classical CAN channels */
+        param = &es581_4_param;
+        ops = &es581_4_ops;
+        num_can_ch = ES581_4_NUM_CAN_CH;
+        break;
+
+    case ES582_1_PRODUCT_ID:    /* 2 CAN(-FD) channels */
+        param = &es58x_fd_param;
+        ops = &es58x_fd_ops;
+        num_can_ch = ES582_1_NUM_CAN_CH;
+        break;
+
+    case ES584_1_PRODUCT_ID:    /* 1 CAN(-FD) and 1 LIN channel */
+        param = &es58x_fd_param;
+        ops = &es58x_fd_ops;
+        num_can_ch = ES584_1_NUM_CAN_CH;
+        break;
+
+    default:
+        return -ENODEV;
+    }
+    if (num_can_ch > ARRAY_SIZE(es58x_dev->netdev) ||
+        num_can_ch >= param->echo_skb_max)
+        return -ECHRNG;
+
+    es58x_dev = kzalloc(es58x_sizeof_es58x_device(param), GFP_KERNEL);
+    if (!es58x_dev)
+        return -ENOMEM;
+
+    es58x_dev->param = param;
+    es58x_dev->ops = ops;
+    es58x_dev->num_can_ch = num_can_ch;
+    es58x_dev->dev = dev;
+    es58x_dev->udev = udev;
+
+    init_usb_anchor(&es58x_dev->rx_urbs);
+    init_usb_anchor(&es58x_dev->tx_urbs_idle);
+    init_usb_anchor(&es58x_dev->tx_urbs_busy);
+    usb_set_intfdata(intf, es58x_dev);
+
+    es58x_dev->rx_pipe = usb_rcvbulkpipe(es58x_dev->udev,
+                         ep_in->bEndpointAddress);
+    es58x_dev->tx_pipe = usb_sndbulkpipe(es58x_dev->udev,
+                         ep_out->bEndpointAddress);
+    es58x_dev->rx_max_packet_size = le16_to_cpu(ep_in->wMaxPacketSize);
+
+    *p_es58x_dev = es58x_dev;
+
+    return 0;
+}
+
+/**
+ * es58x_probe() - Initialize the USB device.
+ * @intf: USB interface
+ * @id: USB device ID
+ *
+ * Return: zero on success, -ENODEV if the interface is not supported
+ * or errno when any other error occurs.
+ */
+static int es58x_probe(struct usb_interface *intf,
+               const struct usb_device_id *id)
+{
+    struct es58x_device *es58x_dev;
+    int ch_idx, ret;
+
+    /* ES58X FD has some interface protocols unsupported by this driver. */
+    if (intf->cur_altsetting->desc.bInterfaceProtocol != 0) {
+        dev_dbg(&intf->dev, "Interface protocol %d is not supported\n",
+            intf->cur_altsetting->desc.bInterfaceProtocol);
+        return -ENODEV;
+    }
+
+    ret = es58x_init_es58x_dev(intf, &es58x_dev);
+    if (ret)
+        return ret;
+
+    ret = es58x_get_product_info(es58x_dev);
+    if (ret)
+        goto cleanup_es58x_dev;
+
+    for (ch_idx = 0; ch_idx < es58x_dev->num_can_ch; ch_idx++) {
+        ret = es58x_init_netdev(es58x_dev, ch_idx);
+        if (ret)
+            goto cleanup_candev;
+    }
+
+    ret = es58x_start(es58x_dev);
+    if (ret)
+        goto cleanup_candev;
+
+    es58x_set_realtime_diff_ns(es58x_dev);
+
+    return ret;
+
+ cleanup_candev:
+    for (ch_idx = 0; ch_idx < es58x_dev->num_can_ch; ch_idx++)
+        if (es58x_dev->netdev[ch_idx]) {
+            unregister_candev(es58x_dev->netdev[ch_idx]);
+            free_candev(es58x_dev->netdev[ch_idx]);
+        }
+ cleanup_es58x_dev:
+    kfree(es58x_dev);
+
+    return ret;
+}
+
+/**
+ * es58x_disconnect() - Disconnect the USB device.
+ * @intf: USB interface
+ *
+ * Called by the usb core when driver is unloaded or device is
+ * removed.
+ */
+static void es58x_disconnect(struct usb_interface *intf)
+{
+    struct es58x_device *es58x_dev = usb_get_intfdata(intf);
+    struct net_device *netdev;
+    struct urb *urb;
+    int i;
+
+    dev_info(&intf->dev, "Disconnecting %s %s\n",
+         es58x_dev->udev->manufacturer, es58x_dev->udev->product);
+
+    for (i = 0; i < es58x_dev->num_can_ch; i++) {
+        netdev = es58x_dev->netdev[i];
+        if (!netdev)
+            continue;
+        netdev_dbg(netdev, "Unregistering %s\n", netdev->name);
+        unregister_candev(netdev);
+        netdev_dbg(netdev, "Freeing %s\n", netdev->name);
+        es58x_dev->netdev[i] = NULL;
+        free_candev(netdev);
+    }
+
+    dev_dbg(&intf->dev, "Killing TX busy anchored urbs\n");
+    if (!usb_wait_anchor_empty_timeout(&es58x_dev->tx_urbs_busy, 1000)) {
+        dev_err(&intf->dev, "%s: Timeout, some TX urbs still remain\n",
+            __func__);
+        usb_kill_anchored_urbs(&es58x_dev->tx_urbs_busy);
+    }
+
+    dev_dbg(&intf->dev, "Freeing TX idle anchored urbs\n");
+    while ((urb = usb_get_from_anchor(&es58x_dev->tx_urbs_idle)) != NULL) {
+        usb_free_coherent(urb->dev,
+                  es58x_dev->param->tx_urb_cmd_max_len,
+                  urb->transfer_buffer, urb->transfer_dma);
+        usb_free_urb(urb);
+        atomic_dec(&es58x_dev->tx_urbs_idle_cnt);
+    }
+    if (atomic_read(&es58x_dev->tx_urbs_idle_cnt) > 0)
+        dev_err(&intf->dev,
+            "All idle urbs were freed but tx_urb_idle_cnt is %u\n",
+            atomic_read(&es58x_dev->tx_urbs_idle_cnt));
+
+    dev_dbg(&intf->dev, "Unlinking RX anchored urbs\n");
+    usb_kill_anchored_urbs(&es58x_dev->rx_urbs);
+
+    dev_dbg(&intf->dev, "Freeing %s\n", es58x_dev->udev->product);
+    kfree(es58x_dev);
+    dev_dbg(&intf->dev, "Setting USB interface to NULL\n");
+    usb_set_intfdata(intf, NULL);
+}
+
+static struct usb_driver es58x_driver = {
+    .name = ES58X_MODULE_NAME,
+    .probe = es58x_probe,
+    .disconnect = es58x_disconnect,
+    .id_table = es58x_id_table,
+};
+
+module_usb_driver(es58x_driver);
diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.h
b/drivers/net/can/usb/etas_es58x/es58x_core.h
new file mode 100644
index 000000000000..b32f9acf6eb6
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es58x_core.h
@@ -0,0 +1,724 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es58x_core.h: All common definitions and declarations.
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#ifndef __ES58X_COMMON_H__
+#define __ES58X_COMMON_H__
+
+#include <linux/types.h>
+#include <linux/usb.h>
+#include <linux/netdevice.h>
+#include <linux/can.h>
+#include <linux/can/dev.h>
+
+#include "es581_4.h"
+#include "es58x_fd.h"
+
+/* Size of a Classical CAN Standard Frame (rounded up and ignoring
+ * bitsuffing).
+ */
+#define ES58X_SFF_BYTES(data_len) (DIV_ROUND_UP(47, 8) + (data_len))
+
+/* Size of a Classical CAN Extended Frame (rounded up and ignoring
+ * bitsuffing).
+ */
+#define ES58X_EFF_BYTES(data_len) (DIV_ROUND_UP(67, 8) + (data_len))
+
+/* Maximum size of a Classical CAN frame (rounded up and ignoring
+ * bitsuffing).
+ */
+#define ES58X_CAN_FRAME_BYTES_MAX ES58X_EFF_BYTES(CAN_MAX_DLEN)
+
+/* Maximum size of a CAN-FD frame (rough estimation because
+ * ES58X_SFF_BYTES() and ES58X_EFF_BYTES() macros are using the
+ * constant values for Classical CAN, not CAN-FD).
+ */
+#define ES58X_CANFD_FRAME_BYTES_MAX ES58X_EFF_BYTES(CANFD_MAX_DLEN)
+
+/* Driver constants */
+#define ES58X_RX_URBS_MAX 5    /* Empirical value */
+#define ES58X_TX_URBS_MAX 8    /* Empirical value */
+
+#define ES58X_MAX(param)                \
+    (ES581_4_##param > ES58X_FD_##param ?        \
+        ES581_4_##param : ES58X_FD_##param)
+#define ES58X_TX_BULK_MAX ES58X_MAX(TX_BULK_MAX)
+#define ES58X_RX_BULK_MAX ES58X_MAX(RX_BULK_MAX)
+#define ES58X_RX_LOOPBACK_BULK_MAX ES58X_MAX(RX_LOOPBACK_BULK_MAX)
+#define ES58X_NUM_CAN_CH_MAX ES58X_MAX(NUM_CAN_CH)
+
+/* Use this when channel index is irrelevant (e.g. device
+ * timestamp).
+ */
+#define ES58X_CHANNEL_IDX_NA 0xFF
+#define ES58X_EMPTY_MSG NULL
+
+/* Threshold on consecutive CAN_STATE_ERROR_PASSIVE. If we receive
+ * ES58X_CONSECUTIVE_ERR_PASSIVE_MAX times the event
+ * ES58X_ERR_CRTL_PASSIVE in a row without any successful Rx or Tx,
+ * we force the device to switch to CAN_STATE_BUS_OFF state.
+ */
+#define ES58X_CONSECUTIVE_ERR_PASSIVE_MAX 254
+
+enum es58x_self_reception {
+    ES58X_SELF_RECEPTION_OFF = 0,
+    ES58X_SELF_RECEPTION_ON = 1
+};
+
+/**
+ * enum es58x_physical_layer - Type of the physical layer.
+ * @ES58X_PHYSICAL_LAYER_HIGH_SPEED: High-speed CAN (c.f. ISO
+ *    11898-2).
+ *
+ * Some products of the ETAS portfolio also support low-speed CAN
+ * (c.f. ISO 11898-3). However, all the devices in scope of this
+ * driver do not support the option, thus, the enum has only one
+ * member.
+ */
+enum es58x_physical_layer {
+    ES58X_PHYSICAL_LAYER_HIGH_SPEED = 1
+};
+
+enum es58x_samples_per_bit {
+    ES58X_SAMPLES_PER_BIT_ONE = 1,
+    ES58X_SAMPLES_PER_BIT_THREE = 2
+};
+
+/**
+ * enum es58x_sync_edge - Synchronization method.
+ * @ES58X_SYNC_EDGE_SINGLE: ISO CAN specification defines the use of a
+ *    single edge synchronization.  The synchronization should be
+ *    done on recessive to dominant level change.
+ *
+ * For information, ES582.1 and ES584.1 also support a double
+ * synchronization, requiring both recessive to dominant then dominant
+ * to recessive level change. However, this is not supported in
+ * SocketCAN framework, thus, the enum has only one member.
+ */
+enum es58x_sync_edge {
+    ES58X_SYNC_EDGE_SINGLE = 1
+};
+
+/**
+ * enum es58x_flag - CAN flags for RX/TX messages.
+ * @ES58X_FLAG_EFF: Extended Frame Format (EFF).
+ * @ES58X_FLAG_RTR: Remote Transmission Request (RTR).
+ * @ES58X_FLAG_FD_BRS: Bit rate switch (BRS): second bitrate for
+ *    payload data.
+ * @ES58X_FLAG_FD_ESI: Error State Indicator (ESI): tell if the
+ *    transmitting node is in error passive mode.
+ * @ES58X_FLAG_FD_DATA: CAN FD frame.
+ */
+enum es58x_flag {
+    ES58X_FLAG_EFF = BIT(0),
+    ES58X_FLAG_RTR = BIT(1),
+    ES58X_FLAG_FD_BRS = BIT(3),
+    ES58X_FLAG_FD_ESI = BIT(5),
+    ES58X_FLAG_FD_DATA = BIT(6)
+};
+
+/**
+ * enum es58x_err - CAN error detection.
+ * @ES58X_ERR_OK: No errors.
+ * @ES58X_ERR_PROT_STUFF: Bit stuffing error: more than 5 consecutive
+ *    equal bits.
+ * @ES58X_ERR_PROT_FORM: Frame format error.
+ * @ES58X_ERR_ACK: Received no ACK on transmission.
+ * @ES58X_ERR_PROT_BIT: Single bit error.
+ * @ES58X_ERR_PROT_CRC: Incorrect 15, 17 or 21 bits CRC.
+ * @ES58X_ERR_PROT_BIT1: Unable to send recessive bit: tried to send
+ *    recessive bit 1 but monitored dominant bit 0.
+ * @ES58X_ERR_PROT_BIT0: Unable to send dominant bit: tried to send
+ *    dominant bit 0 but monitored recessive bit 1.
+ * @ES58X_ERR_PROT_OVERLOAD: Bus overload.
+ * @ES58X_ERR_PROT_UNSPEC: Unspecified.
+ *
+ * Please refer to ISO 11898-1:2015, section 10.11 "Error detection"
+ * and section 10.13 "Overload signaling" for additional details.
+ */
+enum es58x_err {
+    ES58X_ERR_OK = 0,
+    ES58X_ERR_PROT_STUFF = BIT(0),
+    ES58X_ERR_PROT_FORM = BIT(1),
+    ES58X_ERR_ACK = BIT(2),
+    ES58X_ERR_PROT_BIT = BIT(3),
+    ES58X_ERR_PROT_CRC = BIT(4),
+    ES58X_ERR_PROT_BIT1 = BIT(5),
+    ES58X_ERR_PROT_BIT0 = BIT(6),
+    ES58X_ERR_PROT_OVERLOAD = BIT(7),
+    ES58X_ERR_PROT_UNSPEC = BIT(31)
+};
+
+/**
+ * enum es58x_event - CAN error codes returned by the device.
+ * @ES58X_EVENT_OK: No errors.
+ * @ES58X_EVENT_CRTL_ACTIVE: Active state: both TR and RX error count
+ *    is less than 128.
+ * @ES58X_EVENT_CRTL_PASSIVE: Passive state: either TX or RX error
+ *    count is greater than 127.
+ * @ES58X_EVENT_CRTL_WARNING: Warning state: either TX or RX error
+ *    count is greater than 96.
+ * @ES58X_EVENT_BUSOFF: Bus off.
+ * @ES58X_EVENT_SINGLE_WIRE: Lost connection on either CAN high or CAN
+ *    low.
+ *
+ * Please refer to ISO 11898-1:2015, section 12.1.4 "Rules of fault
+ * confinement" for additional details.
+ */
+enum es58x_event {
+    ES58X_EVENT_OK = 0,
+    ES58X_EVENT_CRTL_ACTIVE = BIT(0),
+    ES58X_EVENT_CRTL_PASSIVE = BIT(1),
+    ES58X_EVENT_CRTL_WARNING = BIT(2),
+    ES58X_EVENT_BUSOFF = BIT(3),
+    ES58X_EVENT_SINGLE_WIRE = BIT(4)
+};
+
+/**
+ * enum es58x_ret_u8 - Device return error codes, 8 bit format.
+ *
+ * Specific to ES581.4.
+ */
+enum es58x_ret_u8 {
+    ES58X_RET_U8_OK = 0x00,
+    ES58X_RET_U8_ERR_UNSPECIFIED_FAILURE = 0x80,
+    ES58X_RET_U8_ERR_NO_MEM = 0x81,
+    ES58X_RET_U8_ERR_BAD_CRC = 0x99
+};
+
+/**
+ * enum es58x_ret_u32 - Device return error codes, 32 bit format.
+ */
+enum es58x_ret_u32 {
+    ES58X_RET_U32_OK = 0x00000000UL,
+    ES58X_RET_U32_ERR_UNSPECIFIED_FAILURE = 0x80000000UL,
+    ES58X_RET_U32_ERR_NO_MEM = 0x80004001UL,
+    ES58X_RET_U32_WARN_PARAM_ADJUSTED = 0x40004000UL,
+    ES58X_RET_U32_WARN_TX_MAYBE_REORDER = 0x40004001UL,
+    ES58X_RET_U32_ERR_TIMEOUT = 0x80000008UL,
+    ES58X_RET_U32_ERR_FIFO_FULL = 0x80003002UL,
+    ES58X_RET_U32_ERR_BAD_CONFIG = 0x80004000UL,
+    ES58X_RET_U32_ERR_NO_RESOURCE = 0x80004002UL
+};
+
+/**
+ * enum es58x_ret_type - Type of the command returned by the ES58X
+ *    device.
+ */
+enum es58x_ret_type {
+    ES58X_RET_TYPE_SET_BITTIMING,
+    ES58X_RET_TYPE_ENABLE_CHANNEL,
+    ES58X_RET_TYPE_DISABLE_CHANNEL,
+    ES58X_RET_TYPE_TX_MSG,
+    ES58X_RET_TYPE_RESET_RX,
+    ES58X_RET_TYPE_RESET_TX,
+    ES58X_RET_TYPE_DEVICE_ERR,
+    ES58X_RET_TYPE_NUM_ENTRIES
+};
+
+union es58x_urb_cmd {
+    struct es581_4_urb_cmd es581_4_urb_cmd;
+    struct es58x_fd_urb_cmd es58x_fd_urb_cmd;
+    struct {        /* Common header parts of all variants */
+        __le16 sof;
+        u8 cmd_type;
+        u8 cmd_id;
+    } __packed;
+    u8 raw_cmd[0];
+};
+
+/**
+ * struct es58x_priv - All information specific to a can channel.
+ * @can: struct can_priv must be the first member (Socket CAN relies
+ *    on the fact that function netdev_priv() returns a pointer to
+ *    a struct can_priv).
+ * @es58x_dev: pointer to the corresponding ES58X device.
+ * @tx_urb: Used as a buffer to concatenate the TX messages and to do
+ *    a bulk send. Please refer to es58x_start_xmit() for more
+ *    details.
+ * @echo_skb_spinlock: Spinlock to protect the access to the echo skb
+ *    FIFO.
+ * @current_packet_idx: Keeps track of the packet indexes.
+ * @echo_skb_tail_idx: beginning of the echo skb FIFO, i.e. index of
+ *    the first element.
+ * @echo_skb_head_idx: end of the echo skb FIFO plus one, i.e. first
+ *    free index.
+ * @num_echo_skb: actual number of elements in the FIFO. Thus, the end
+ *    of the FIFO is echo_skb_head = (echo_skb_tail_idx +
+ *    num_echo_skb) % can.echo_skb_max.
+ * @tx_can_msg_is_fd: false: all messages in @tx_urb are Classical
+ *    CAN, true: all messages in @tx_urb are CAN-FD. Rationale:
+ *    ES58X FD devices do not allow to mix standard and FD CAN in
+ *    one single bulk transmission.
+ * @tx_can_msg_cnt: Number of messages in @tx_urb.
+ * @err_passive_before_rtx_success: The ES58X device might enter in a
+ *    state in which it keeps alternating between error passive
+ *    and active state. This counter keeps track of the number of
+ *    error passive and if it gets bigger than
+ *    ES58X_CONSECUTIVE_ERR_PASSIVE_MAX, es58x_rx_err_msg() will
+ *    force the status to bus-off.
+ * @channel_idx: Channel index, starts at zero.
+ */
+struct es58x_priv {
+    struct can_priv can;
+    struct es58x_device *es58x_dev;
+    struct urb *tx_urb;
+
+    spinlock_t echo_skb_spinlock;    /* Comments: c.f. supra */
+    u32 current_packet_idx;
+    u16 echo_skb_tail_idx;
+    u16 echo_skb_head_idx;
+    u16 num_echo_skb;
+
+    bool tx_can_msg_is_fd;
+    u8 tx_can_msg_cnt;
+
+    u8 err_passive_before_rtx_success;
+
+    u8 channel_idx;
+};
+
+/**
+ * struct es58x_parameters - Constant parameters of a given hardware
+ *    variant.
+ * @can_bittiming_const: Nominal bittimming parameters.
+ * @data_bittiming_const: Data bittiming parameters.
+ * @bitrate_max: Maximum bitrate supported by the device.
+ * @clock: CAN clock parameters.
+ * @ctrlmode_supported: List of supported modes. Please refer to
+ *    can/netlink.h file for additional details.
+ * @tx_start_of_frame: Magic number at the beginning of each TX URB
+ *    command.
+ * @rx_start_of_frame: Magic number at the beginning of each RX URB
+ *    command.
+ * @tx_urb_cmd_max_len: Maximum length of a TX URB command.
+ * @rx_urb_cmd_max_len: Maximum length of a RX URB command.
+ * @echo_skb_max: Maximum number of echo SKB. This value must not
+ *    exceed the maximum size of the device internal TX FIFO
+ *    length. This parameter is used to control the network queue
+ *    wake/stop logic.
+ * @dql_limit_min: Dynamic Queue Limits (DQL) absolute minimum limit
+ *    of bytes allowed to be queued on this network device transmit
+ *    queue. Used by the Byte Queue Limits (BQL) to determine how
+ *    frequently the xmit_more flag will be set to true in
+ *    es58x_start_xmit(). Set this value higher to optimize for
+ *    throughput but be aware that it might have a negative impact
+ *    on the latency! This value can also be set dynamically. Please
+ *    refer to Documentation/ABI/testing/sysfs-class-net-queues for
+ *    more details.
+ * @tx_bulk_max: Maximum number of Tx messages that can be sent in one
+ *    single URB packet.
+ * @urb_cmd_header_len: Length of the URB command header.
+ * @rx_urb_max: Number of RX URB to be allocated during device probe.
+ * @tx_urb_max: Number of TX URB to be allocated during device probe.
+ * @channel_idx_offset: Some of the ES58x starts channel numbering
+ *    from 0 (ES58X FD), others from 1 (ES581.4).
+ */
+struct es58x_parameters {
+    const struct can_bittiming_const *bittiming_const;
+    const struct can_bittiming_const *data_bittiming_const;
+    u32 bitrate_max;
+    struct can_clock clock;
+    u32 ctrlmode_supported;
+    u16 tx_start_of_frame;
+    u16 rx_start_of_frame;
+    u16 tx_urb_cmd_max_len;
+    u16 rx_urb_cmd_max_len;
+    u16 echo_skb_max;
+#ifdef CONFIG_BQL
+    u16 dql_limit_min;
+#endif
+    u8 tx_bulk_max;
+    u8 urb_cmd_header_len;
+    u8 rx_urb_max;
+    u8 tx_urb_max;
+    u8 channel_idx_offset;
+};
+
+/**
+ * struct es58x_operators - Function pointers used to encode/decode
+ *    the TX/RX messages.
+ * @get_msg_len: Get field msg_len of the urb_cmd. The offset of
+ *    msg_len inside urb_cmd depends of the device model.
+ * @handle_urb_cmd: Handle URB command received from the device and
+ *    manage the return code from device.
+ * @fill_urb_header: Fill the header of urb_cmd.
+ * @tx_can_msg: Encode a TX CAN message and add it to the bulk buffer
+ *    cmd_buf of es58x_dev.
+ * @set_bittiming: Encode the bittiming information and send it.
+ * @enable_channel: Start the CAN channel with index channel_idx.
+ * @disable_channel: Stop the CAN channel with index channel_idx.
+ * @reset_rx: Reset the RX queue of the ES58X device.
+ * @reset_tx: Reset the TX queue of the ES58X device.
+ * @get_timestamp: Request a timestamp from the ES58X device.
+ */
+struct es58x_operators {
+    u16 (*get_msg_len)(const union es58x_urb_cmd *urb_cmd);
+    int (*handle_urb_cmd)(struct es58x_device *es58x_dev,
+                  const union es58x_urb_cmd *urb_cmd);
+    void (*fill_urb_header)(union es58x_urb_cmd *urb_cmd, u8 cmd_type,
+                u8 cmd_id, u8 channel_idx, u16 cmd_len);
+    int (*tx_can_msg)(struct es58x_priv *priv, int channel_idx,
+              u32 packet_idx, const struct sk_buff *skb,
+               union es58x_urb_cmd *urb_cmd, u32 *urb_cmd_len);
+    int (*set_bittiming)(struct es58x_device *es58x_dev, int channel_idx);
+    int (*enable_channel)(struct es58x_device *es58x_dev,
+                  int channel_idx);
+    int (*disable_channel)(struct es58x_device *es58x_dev,
+                   int channel_idx);
+    int (*reset_rx)(struct es58x_device *es58x_dev, int channel_idx);
+    int (*reset_tx)(struct es58x_device *es58x_dev, int channel_idx);
+    int (*get_timestamp)(struct es58x_device *es58x_dev);
+};
+
+/**
+ * struct es58x_device - All information specific to an ES58X device.
+ * @dev: Device information.
+ * @udev: USB device information.
+ * @netdev: Array of our CAN channels.
+ * @param: The constant parameters.
+ * @ops: Operators.
+ * @rx_pipe: USB reception pipe.
+ * @tx_pipe: USB transmission pipe.
+ * @rx_urbs: Anchor for received URBs.
+ * @tx_urbs_busy: Anchor for TX URBs which were send to the device.
+ * @tx_urbs_idle: Anchor for TX USB which are idle. This driver
+ *    allocates the memory for the URBs during the probe. When a TX
+ *    URB is needed, it can be taken from this anchor. The network
+ *    queue wake/stop logic should prevent this URB from getting
+ *    empty. Please refer to es58x_get_tx_urb() for more details.
+ * @tx_urbs_idle_cnt: number of urbs in @tx_urbs_idle.
+ * @ktime_req_ns: kernel timestamp when es58x_set_realtime_diff_ns()
+ *    was called.
+ * @realtime_diff_ns: difference in nanoseconds between the clocks of
+ *    the ES58X device and the kernel.
+ * @timestamps: a temporary buffer to store the time stamps before
+ *    feeding them to es58x_can_get_echo_skb(). Can only be used
+ *    in rx branches.
+ * @rx_max_packet_size: Maximum length of bulk-in URB.
+ * @num_can_ch: Number of CAN channel (i.e. number of elements of @netdev).
+ * @rx_cmd_buf_len: Length of @rx_cmd_buf.
+ * @rx_cmd_buf: The device might split the URB commands in an
+ *    arbitrary amount of pieces. This buffer is used to concatenate
+ *    all those pieces. Can only be used in rx branches. This field
+ *    has to be the last one of the structure because it is has a
+ *    flexible size (c.f. es58x_sizeof_es58x_device() function).
+ */
+struct es58x_device {
+    struct device *dev;
+    struct usb_device *udev;
+    struct net_device *netdev[ES58X_NUM_CAN_CH_MAX];
+
+    const struct es58x_parameters *param;
+    const struct es58x_operators *ops;
+
+    int rx_pipe;
+    int tx_pipe;
+
+    struct usb_anchor rx_urbs;
+    struct usb_anchor tx_urbs_busy;
+    struct usb_anchor tx_urbs_idle;
+    atomic_t tx_urbs_idle_cnt;
+
+    u64 ktime_req_ns;
+    s64 realtime_diff_ns;
+
+    u64 timestamps[ES58X_RX_LOOPBACK_BULK_MAX];
+
+    u16 rx_max_packet_size;
+    u8 num_can_ch;
+
+    u16 rx_cmd_buf_len;
+    union es58x_urb_cmd rx_cmd_buf;
+};
+
+/**
+ * es58x_sizeof_es58x_device() - Calculate the maximum length of
+ *    struct es58x_device.
+ * @es58x_dev_param: The constant parameters of the device.
+ *
+ * The length of struct es58x_device depends on the length of its last
+ * field: rx_cmd_buf. This macro allows to optimize size for memory
+ * allocation.
+ *
+ * Return: length of struct es58x_device.
+ */
+static inline size_t es58x_sizeof_es58x_device(const struct es58x_parameters
+                           *es58x_dev_param)
+{
+    return offsetof(struct es58x_device, rx_cmd_buf) +
+        es58x_dev_param->rx_urb_cmd_max_len;
+}
+
+/* Megabit per second (multiply x per one million) */
+#define ES58X_MBPS(x) (1000000UL * (x))
+
+/* Megahertz (multiply x per one million) */
+#define ES58X_MHZ(x) (1000000UL * (x))
+
+static inline int __es58x_check_msg_len(const struct device *dev,
+                    const char *stringified_msg,
+                    size_t actual_len, size_t expected_len)
+{
+    if (expected_len != actual_len) {
+        dev_err(dev,
+            "Length of %s is %zu but received command is %zu.\n",
+            stringified_msg, expected_len, actual_len);
+        return -EMSGSIZE;
+    }
+    return 0;
+}
+
+/**
+ * es58x_check_msg_len() - Check the size of a received message.
+ * @dev: Device, used to print error messages.
+ * @msg: Received message, must not be a pointer.
+ * @actual_len: Length of the message as advertised in the command header.
+ *
+ * Must be a macro in order to retrieve the actual size using
+ * sizeof(). Can be use with any of the messages which have a fixed
+ * length. Check for an exact match of the size.
+ *
+ * Return: zero on success, -EMSGSIZE if @actual_len differs from the
+ * expected length.
+ */
+#define es58x_check_msg_len(dev, msg, actual_len)            \
+    __es58x_check_msg_len(dev, __stringify(msg),            \
+                  actual_len, sizeof(msg))
+
+static inline int __es58x_check_msg_max_len(const struct device *dev,
+                        const char *stringified_msg,
+                        size_t actual_len,
+                        size_t expected_len)
+{
+    if (actual_len > expected_len) {
+        dev_err(dev,
+            "Maximum length for %s is %zu but received command is %zu.\n",
+            stringified_msg, expected_len, actual_len);
+        return -EOVERFLOW;
+    }
+    return 0;
+}
+
+/**
+ * es58x_check_msg_max_len() - Check the maximum size of a received message.
+ * @dev: Device, used to print error messages.
+ * @msg: Received message, must not be a pointer.
+ * @actual_len: Length of the message as advertised in the command header.
+ *
+ * Must be a macro in order to retrieve the actual size using
+ * sizeof(). To be used with the messages of variable sizes. Only
+ * check that the message is not bigger than the maximum expected
+ * size.
+ *
+ * Return: zero on success, -EOVERFLOW if @actual_len is greater than
+ * the expected length.
+ */
+#define es58x_check_msg_max_len(dev, msg, actual_len)            \
+    __es58x_check_msg_max_len(dev, __stringify(msg),        \
+                  actual_len, sizeof(msg))
+
+static inline int __es58x_msg_num_element(const struct device *dev,
+                      const char *stringified_msg,
+                      size_t actual_len, size_t msg_len,
+                      size_t elem_len)
+{
+    size_t actual_num_elem = actual_len / elem_len;
+    size_t expected_num_elem = msg_len / elem_len;
+
+    if (actual_num_elem == 0) {
+        dev_err(dev,
+            "Minimum length for %s is %zu but received command is %zu.\n",
+            stringified_msg, elem_len, actual_len);
+        return -EMSGSIZE;
+    } else if ((actual_len % elem_len) != 0) {
+        dev_err(dev,
+            "Received command length: %zu is not a multiple of %s[0]: %zu\n",
+            actual_len, stringified_msg, elem_len);
+        return -EMSGSIZE;
+    } else if (actual_num_elem > expected_num_elem) {
+        dev_err(dev,
+            "Array %s is supposed to have %zu elements each of size %zu...\n",
+            stringified_msg, expected_num_elem, elem_len);
+        dev_err(dev,
+            "... But received command has %zu elements (total length %zu).\n",
+            actual_num_elem, actual_len);
+        return -EOVERFLOW;
+    }
+    return actual_num_elem;
+}
+
+/**
+ * es58x_msg_num_element() - Check size and give the number of
+ *    elements in a message of array type.
+ * @dev: Device, used to print error messages.
+ * @msg: Received message, must be an array.
+ * @actual_len: Length of the message as advertised in the command
+ *    header.
+ *
+ * Must be a macro in order to retrieve the actual size using
+ * sizeof(). To be used on message of array type. Array's element has
+ * to be of fixed size (else use es58x_check_msg_max_len()). Check
+ * that the total length is an exact multiple of the length of a
+ * single element.
+ *
+ * Return: number of elements in the array on success, -EOVERFLOW if
+ * @actual_len is greater than the expected length, -EMSGSIZE if
+ * @actual_len is not a multiple of a single element.
+ */
+#define es58x_msg_num_element(dev, msg, actual_len)            \
+({                                    \
+    size_t __elem_len = sizeof((msg)[0]) + __must_be_array(msg);    \
+    __es58x_msg_num_element(dev, __stringify(msg), actual_len,    \
+                sizeof(msg), __elem_len);        \
+})
+
+/**
+ * es58x_priv() - Get the priv member and cast it to struct es58x_priv.
+ * @netdev: CAN network device.
+ *
+ * Return: ES58X device.
+ */
+static inline struct es58x_priv *es58x_priv(struct net_device *netdev)
+{
+    return (struct es58x_priv *)netdev_priv(netdev);
+}
+
+/**
+ * ES58X_SIZEOF_URB_CMD() - Calculate the maximum length of an urb
+ *    command for a given message field name.
+ * @es58x_urb_cmd_type: type (either "struct es581_4_urb_cmd" or
+ *    "struct es58x_fd_urb_cmd").
+ * @msg_field: name of the message field.
+ *
+ * Must be a macro in order to retrieve the actual size using
+ * offsetof() and sizeof_field().
+ *
+ * Return: length of the urb command.
+ */
+#define ES58X_SIZEOF_URB_CMD(es58x_urb_cmd_type, msg_field)        \
+    (offsetof(es58x_urb_cmd_type, raw_msg)                \
+        + sizeof_field(es58x_urb_cmd_type, msg_field)        \
+        + sizeof_field(es58x_urb_cmd_type,            \
+                   reserved_for_crc16_do_not_use))
+
+/**
+ * es58x_get_urb_cmd_len() - Calculate the actual length of an urb
+ *    command for a given message length.
+ * @es58x_dev: ES58X device.
+ * @msg_len: Length of the message.
+ *
+ * Add the header and CRC lengths to the message length.
+ *
+ * Return: length of the urb command.
+ */
+static inline size_t es58x_get_urb_cmd_len(struct es58x_device *es58x_dev,
+                       u16 msg_len)
+{
+    /* URB Length = URB header len + Message len + sizeof crc16 */
+    return es58x_dev->param->urb_cmd_header_len + msg_len + sizeof(u16);
+}
+
+/**
+ * es58x_get_netdev() - Get the network device.
+ * @es58x_dev: ES58X device.
+ * @channel_no: The channel number as advertised in the urb command.
+ * @netdev: CAN network device.
+ *
+ * ES581.4 starts the numbering on channels from 1, ES58X FD family
+ * starts it from 0. This method does the sanity check.
+ *
+ * Return: zero on success, -ECHRNG if the received channel number is
+ * out of range and -ENODEV if the network device is not yet
+ * configured.
+ */
+static inline int es58x_get_netdev(struct es58x_device *es58x_dev,
+                   int channel_no, struct net_device **netdev)
+{
+    int channel_idx = channel_no - es58x_dev->param->channel_idx_offset;
+
+    *netdev = NULL;
+    if (channel_idx < 0 || channel_idx >= es58x_dev->num_can_ch)
+        return -ECHRNG;
+
+    *netdev = es58x_dev->netdev[channel_idx];
+    if (!netdev || !netif_device_present(*netdev))
+        return -ENODEV;
+
+    return 0;
+}
+
+/**
+ * es58x_get_raw_can_id() - Get the CAN ID.
+ * @cf: CAN frame.
+ *
+ * Mask the CAN ID in order to only keep the significant bits.
+ *
+ * Return: the raw value of the CAN ID.
+ */
+static inline int es58x_get_raw_can_id(const struct can_frame *cf)
+{
+    if (cf->can_id & CAN_EFF_FLAG)
+        return cf->can_id & CAN_EFF_MASK;
+    else
+        return cf->can_id & CAN_SFF_MASK;
+}
+
+/**
+ * es58x_get_flags() - Get the CAN flags.
+ * @skb: socket buffer of a CAN message.
+ *
+ * Return: the CAN flag as an enum es58x_flag.
+ */
+static inline enum es58x_flag es58x_get_flags(const struct sk_buff *skb)
+{
+    struct canfd_frame *cf = (struct canfd_frame *)skb->data;
+    enum es58x_flag es58x_flags = 0;
+
+    if (cf->can_id & CAN_EFF_FLAG)
+        es58x_flags |= ES58X_FLAG_EFF;
+
+    if (can_is_canfd_skb(skb)) {
+        es58x_flags |= ES58X_FLAG_FD_DATA;
+        if (cf->flags & CANFD_BRS)
+            es58x_flags |= ES58X_FLAG_FD_BRS;
+        if (cf->flags & CANFD_ESI)
+            es58x_flags |= ES58X_FLAG_FD_ESI;
+    } else if (cf->can_id & CAN_RTR_FLAG)
+        /* Remote frames are only defined in Classical CAN frames */
+        es58x_flags |= ES58X_FLAG_RTR;
+
+    return es58x_flags;
+}
+
+int es58x_can_get_echo_skb(struct net_device *netdev, u32 packet_idx,
+               u64 *tstamps, unsigned int pkts);
+int es58x_tx_ack_msg(struct net_device *netdev, u16 tx_free_entries,
+             enum es58x_ret_u32 rx_cmd_ret_u32);
+int es58x_rx_can_msg(struct net_device *netdev, u64 timestamp, const u8 *data,
+             canid_t can_id, enum es58x_flag es58x_flags, u8 dlc);
+int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
+             enum es58x_event event, u64 timestamp);
+int es58x_rx_timestamp(struct es58x_device *es58x_dev, u64 timestamp);
+int es58x_rx_dev_ret_u8(struct device *dev, enum es58x_ret_type cmd_ret_type,
+            enum es58x_ret_u8 rx_dev_ret_u8);
+int es58x_rx_cmd_ret_u32(struct net_device *netdev,
+             enum es58x_ret_type cmd_ret_type,
+             enum es58x_ret_u32 rx_cmd_ret_u32);
+int es58x_send_msg(struct es58x_device *es58x_dev, u8 cmd_type, u8 cmd_id,
+           const void *msg, u16 cmd_len, int channel_idx);
+
+extern const struct es58x_parameters es581_4_param;
+extern const struct es58x_operators es581_4_ops;
+
+extern const struct es58x_parameters es58x_fd_param;
+extern const struct es58x_operators es58x_fd_ops;
+
+#endif /* __ES58X_COMMON_H__ */
diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.c
b/drivers/net/can/usb/etas_es58x/es58x_fd.c
new file mode 100644
index 000000000000..3f81002e0a71
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es58x_fd.c
@@ -0,0 +1,658 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es58x_fd.c: Adds support to ETAS ES582.1 and ES584.1 (naming
+ * convention: we use the term "ES58X FD" when referring to those two
+ * variants together).
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <asm/unaligned.h>
+
+#include "es58x_core.h"
+#include "es58x_fd.h"
+
+/**
+ * es58x_sizeof_rx_tx_msg() - Calculate the actual length of the
+ *    structure of a rx or tx message.
+ * @msg: message of variable length, must have a dlc and a len fields.
+ *
+ * Even if RTR frames have actually no payload, the ES58X devices
+ * still expect it. Must be a macro in order to retrieve the actual
+ * size using offsetof() and typeof().
+ *
+ * Return: length of the message.
+ */
+#define es58x_fd_sizeof_rx_tx_msg(msg)                    \
+({                                    \
+    typeof(msg) __msg = (msg);                    \
+    size_t __msg_len = __msg.flags & ES58X_FLAG_FD_DATA ?        \
+        min_t(u8, __msg.len, CANFD_MAX_DLEN) :            \
+        can_cc_dlc2len(__msg.dlc);                \
+    (offsetof(typeof(__msg), data[__msg_len]));            \
+})
+
+static enum es58x_fd_cmd_type es58x_fd_cmd_type(struct net_device *netdev)
+{
+    u32 ctrlmode = es58x_priv(netdev)->can.ctrlmode;
+
+    return ctrlmode & (CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO) ?
+        ES58X_FD_CMD_TYPE_CANFD : ES58X_FD_CMD_TYPE_CAN;
+}
+
+static u16 es58x_fd_get_msg_len(const union es58x_urb_cmd *urb_cmd)
+{
+    return get_unaligned_le16(&urb_cmd->es58x_fd_urb_cmd.msg_len);
+}
+
+static int es58x_fd_rx_loopback_msg(struct net_device *netdev,
+                    const struct es58x_fd_urb_cmd
+                    *es58x_fd_urb_cmd)
+{
+    struct es58x_priv *priv = es58x_priv(netdev);
+    const struct es58x_fd_rx_loopback_msg *rx_loopback_msg;
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    u64 *tstamps = es58x_dev->timestamps;
+    u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    int i, num_element;
+    u32 first_packet_idx, packet_idx;
+    unsigned long flags;
+
+    const u32 mask = ~(u32)((typeof(rx_loopback_msg->packet_idx))(~0U));
+
+    num_element = es58x_msg_num_element(es58x_dev->dev,
+                        es58x_fd_urb_cmd->rx_loopback_msg,
+                        msg_len);
+    if (num_element < 0)
+        return num_element;
+    rx_loopback_msg = es58x_fd_urb_cmd->rx_loopback_msg;
+
+    spin_lock_irqsave(&priv->echo_skb_spinlock, flags);
+    first_packet_idx = priv->current_packet_idx - priv->num_echo_skb;
+    spin_unlock_irqrestore(&priv->echo_skb_spinlock, flags);
+
+    packet_idx = (first_packet_idx & mask) | rx_loopback_msg[0].packet_idx;
+    for (i = 0; i < num_element; i++) {
+        if ((u8)packet_idx != rx_loopback_msg[i].packet_idx) {
+            netdev_err(netdev, "Packet idx jumped from %u to %u\n",
+                   (u8)packet_idx - 1,
+                   rx_loopback_msg[i].packet_idx);
+            return -EBADMSG;
+        }
+
+        tstamps[i] = get_unaligned_le64(&rx_loopback_msg[i].timestamp);
+        packet_idx++;
+    }
+
+    return es58x_can_get_echo_skb(netdev, first_packet_idx,
+                      tstamps, num_element);
+}
+
+static int es58x_fd_rx_can_msg(struct net_device *netdev,
+                   const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    const u8 *rx_can_msg_buf = es58x_fd_urb_cmd->rx_can_msg_buf;
+    u16 rx_can_msg_buf_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    int pkts, ret;
+
+    ret = es58x_check_msg_max_len(es58x_dev->dev,
+                      es58x_fd_urb_cmd->rx_can_msg_buf,
+                      rx_can_msg_buf_len);
+    if (ret)
+        return ret;
+
+    for (pkts = 0; rx_can_msg_buf_len > 0; pkts++) {
+        const struct es58x_fd_rx_can_msg *rx_can_msg =
+            (const struct es58x_fd_rx_can_msg *)rx_can_msg_buf;
+        bool is_can_fd = !!(rx_can_msg->flags & ES58X_FLAG_FD_DATA);
+        /* rx_can_msg_len is the length of the rx_can_msg
+         * buffer. Not to be confused with rx_can_msg->len
+         * which is the length of the CAN payload
+         * rx_can_msg->data.
+         */
+        u16 rx_can_msg_len = es58x_fd_sizeof_rx_tx_msg(*rx_can_msg);
+
+        if (rx_can_msg_len > rx_can_msg_buf_len) {
+            netdev_err(netdev,
+                   "%s: Expected a rx_can_msg of size %d but only %d
bytes are left in rx_can_msg_buf\n",
+                   __func__,
+                   rx_can_msg_len, rx_can_msg_buf_len);
+            return -EMSGSIZE;
+        }
+        if (rx_can_msg->len > CANFD_MAX_DLEN) {
+            netdev_err(netdev,
+                   "%s: Data length is %d but maximum should be %d\n",
+                   __func__, rx_can_msg->len, CANFD_MAX_DLEN);
+            return -EMSGSIZE;
+        }
+
+        if (netif_running(netdev)) {
+            u64 tstamp = get_unaligned_le64(&rx_can_msg->timestamp);
+            canid_t can_id = get_unaligned_le32(&rx_can_msg->can_id);
+            u8 dlc;
+
+            if (is_can_fd)
+                dlc = can_fd_len2dlc(rx_can_msg->len);
+            else
+                dlc = rx_can_msg->dlc;
+
+            ret = es58x_rx_can_msg(netdev, tstamp, rx_can_msg->data,
+                           can_id, rx_can_msg->flags, dlc);
+            if (ret)
+                break;
+        }
+
+        rx_can_msg_buf_len -= rx_can_msg_len;
+        rx_can_msg_buf += rx_can_msg_len;
+    }
+
+    if (!netif_running(netdev)) {
+        if (net_ratelimit())
+            netdev_info(netdev,
+                    "%s: %s is down, dropping %d rx packets\n",
+                    __func__, netdev->name, pkts);
+        netdev->stats.rx_dropped += pkts;
+    }
+
+    return ret;
+}
+
+static int es58x_fd_rx_event_msg(struct net_device *netdev,
+                 const struct es58x_fd_urb_cmd
+                 *es58x_fd_urb_cmd)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    const struct es58x_fd_rx_event_msg *rx_event_msg;
+    int ret;
+
+    ret = es58x_check_msg_len(es58x_dev->dev, *rx_event_msg, msg_len);
+    if (ret)
+        return ret;
+
+    rx_event_msg = &es58x_fd_urb_cmd->rx_event_msg;
+
+    return es58x_rx_err_msg(netdev, rx_event_msg->error_code,
+                rx_event_msg->event_code,
+                get_unaligned_le64(&rx_event_msg->timestamp));
+}
+
+static int es58x_fd_rx_cmd_ret_u32(struct net_device *netdev,
+                   const struct es58x_fd_urb_cmd
+                   *es58x_fd_urb_cmd,
+                   enum es58x_ret_type cmd_ret_type)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    enum es58x_ret_u32 rx_cmd_ret_u32;
+    int ret;
+
+    ret = es58x_check_msg_len(es58x_dev->dev,
+                  es58x_fd_urb_cmd->rx_cmd_ret_le32, msg_len);
+    if (ret)
+        return ret;
+
+    rx_cmd_ret_u32 = get_unaligned_le32(&es58x_fd_urb_cmd->rx_cmd_ret_le32);
+
+    return es58x_rx_cmd_ret_u32(netdev, cmd_ret_type, rx_cmd_ret_u32);
+}
+
+static int es58x_fd_tx_ack_msg(struct net_device *netdev,
+                   const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
+{
+    struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
+    const struct es58x_fd_tx_ack_msg *tx_ack_msg;
+    u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    int ret;
+
+    tx_ack_msg = &es58x_fd_urb_cmd->tx_ack_msg;
+    ret = es58x_check_msg_len(es58x_dev->dev, *tx_ack_msg, msg_len);
+    if (ret)
+        return ret;
+
+    return
+        es58x_tx_ack_msg(netdev,
+                 get_unaligned_le16(&tx_ack_msg->tx_free_entries),
+                 get_unaligned_le32(&tx_ack_msg->rx_cmd_ret_le32));
+}
+
+static int es58x_fd_can_cmd_id(struct es58x_device *es58x_dev,
+                   const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
+{
+    struct net_device *netdev;
+    int ret;
+
+    ret = es58x_get_netdev(es58x_dev, es58x_fd_urb_cmd->channel_idx,
+                   &netdev);
+    if (ret)
+        return ret;
+
+    switch ((enum es58x_fd_can_cmd_id)es58x_fd_urb_cmd->cmd_id) {
+    case ES58X_FD_CAN_CMD_ID_ENABLE_CHANNEL:
+        return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
+                           ES58X_RET_TYPE_ENABLE_CHANNEL);
+
+    case ES58X_FD_CAN_CMD_ID_DISABLE_CHANNEL:
+        return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
+                           ES58X_RET_TYPE_DISABLE_CHANNEL);
+
+    case ES58X_FD_CAN_CMD_ID_TX_MSG:
+        return es58x_fd_tx_ack_msg(netdev, es58x_fd_urb_cmd);
+
+    case ES58X_FD_CAN_CMD_ID_MSG_SELFRX_ACK:
+        return es58x_fd_rx_loopback_msg(netdev, es58x_fd_urb_cmd);
+
+    case ES58X_FD_CAN_CMD_ID_RX_MSG:
+        return es58x_fd_rx_can_msg(netdev, es58x_fd_urb_cmd);
+
+    case ES58X_FD_CAN_CMD_ID_RESET_RX:
+        return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
+                           ES58X_RET_TYPE_RESET_RX);
+
+    case ES58X_FD_CAN_CMD_ID_RESET_TX:
+        return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
+                           ES58X_RET_TYPE_RESET_TX);
+
+    case ES58X_FD_CAN_CMD_ID_ERROR_OR_EVENT_MSG:
+        return es58x_fd_rx_event_msg(netdev, es58x_fd_urb_cmd);
+
+    default:
+        return -EBADRQC;
+    }
+}
+
+static int es58x_fd_device_cmd_id(struct es58x_device *es58x_dev,
+                  const struct es58x_fd_urb_cmd
+                  *es58x_fd_urb_cmd)
+{
+    u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    u64 timestamp;
+    int ret;
+
+    switch ((enum es58x_fd_dev_cmd_id)es58x_fd_urb_cmd->cmd_id) {
+    case ES58X_FD_DEV_CMD_ID_TIMESTAMP:
+        ret = es58x_check_msg_len(es58x_dev->dev,
+                      es58x_fd_urb_cmd->timestamp, msg_len);
+        if (ret)
+            return ret;
+        timestamp = get_unaligned_le64(&es58x_fd_urb_cmd->timestamp);
+        return es58x_rx_timestamp(es58x_dev, timestamp);
+
+    default:
+        return -EBADRQC;
+    }
+}
+
+static int es58x_fd_handle_urb_cmd(struct es58x_device *es58x_dev,
+                   const union es58x_urb_cmd *urb_cmd)
+{
+    const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd;
+    const struct device *dev = es58x_dev->dev;
+    int ret;
+
+    es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
+
+    switch ((enum es58x_fd_cmd_type)es58x_fd_urb_cmd->cmd_type) {
+    case ES58X_FD_CMD_TYPE_CAN:
+    case ES58X_FD_CMD_TYPE_CANFD:
+        ret = es58x_fd_can_cmd_id(es58x_dev, es58x_fd_urb_cmd);
+        break;
+
+    case ES58X_FD_CMD_TYPE_DEVICE:
+        ret = es58x_fd_device_cmd_id(es58x_dev, es58x_fd_urb_cmd);
+        break;
+
+    default:
+        ret = -EBADRQC;
+        break;
+    }
+
+    if (ret == -EBADRQC)
+        dev_err(dev,
+            "%s: Unknown command type (0x%02X) and command ID
(0x%02X) combination\n",
+            __func__, es58x_fd_urb_cmd->cmd_type,
+            es58x_fd_urb_cmd->cmd_id);
+
+    return ret;
+}
+
+static void es58x_fd_fill_urb_header(union es58x_urb_cmd *urb_cmd, u8 cmd_type,
+                     u8 cmd_id, u8 channel_idx, u16 msg_len)
+{
+    struct es58x_fd_urb_cmd *es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
+
+    es58x_fd_urb_cmd->SOF = cpu_to_le16(es58x_fd_param.tx_start_of_frame);
+    es58x_fd_urb_cmd->cmd_type = cmd_type;
+    es58x_fd_urb_cmd->cmd_id = cmd_id;
+    es58x_fd_urb_cmd->channel_idx = channel_idx;
+    es58x_fd_urb_cmd->msg_len = cpu_to_le16(msg_len);
+}
+
+static int es58x_fd_tx_can_msg(struct es58x_priv *priv, int channel_idx,
+                   u32 packet_idx, const struct sk_buff *skb,
+                   union es58x_urb_cmd *urb_cmd, u32 *urb_cmd_len)
+{
+    struct es58x_device *es58x_dev = priv->es58x_dev;
+    struct es58x_fd_urb_cmd *es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
+    struct can_frame *cf = (struct can_frame *)skb->data;
+    struct es58x_fd_tx_can_msg *tx_can_msg;
+    bool is_fd = can_is_canfd_skb(skb);
+    u16 msg_len;
+    int ret;
+
+    ret = es58x_check_msg_max_len(es58x_dev->dev,
+                      es58x_fd_urb_cmd->tx_can_msg_buf,
+                      es58x_fd_get_msg_len(urb_cmd) +
+                      sizeof(*tx_can_msg));
+    if (ret)
+        return ret;
+
+    msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
+    tx_can_msg = (struct es58x_fd_tx_can_msg *)
+        &es58x_fd_urb_cmd->tx_can_msg_buf[msg_len];
+
+    /* Fill message contents. */
+    if (*urb_cmd_len == es58x_dev->param->urb_cmd_header_len)
+        es58x_fd_fill_urb_header(urb_cmd,
+                     is_fd ? ES58X_FD_CMD_TYPE_CANFD
+                           : ES58X_FD_CMD_TYPE_CAN,
+                     ES58X_FD_CAN_CMD_ID_TX_MSG_NO_ACK,
+                     channel_idx, *urb_cmd_len);
+    tx_can_msg->packet_idx = packet_idx;
+    put_unaligned_le32(es58x_get_raw_can_id(cf), &tx_can_msg->can_id);
+    tx_can_msg->flags = (u8)es58x_get_flags(skb);
+    if (is_fd)
+        tx_can_msg->len = cf->len;
+    else
+        tx_can_msg->dlc = can_get_cc_dlc(cf, priv->can.ctrlmode);
+    memcpy(tx_can_msg->data, cf->data, cf->len);
+
+    /* Calculate new sizes */
+    msg_len += es58x_fd_sizeof_rx_tx_msg(*tx_can_msg);
+    *urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
+    put_unaligned_le16(msg_len, &es58x_fd_urb_cmd->msg_len);
+
+    return 0;
+}
+
+/* ES58X uses the same command to set the bittiming parameters and
+ * enable the channel. The modification is done in
+ * es58x_fd_enable_channel().
+ */
+static int es58x_fd_set_bittiming(struct es58x_device *es58x_dev,
+                  int channel_idx)
+{
+    return 0;
+}
+
+static void es58x_fd_print_bittiming(struct net_device *netdev,
+                     struct es58x_fd_bittiming
+                     *es58x_fd_bittiming, char *type)
+{
+    netdev_vdbg(netdev, "bitrate %s    = %d\n", type,
+            le32_to_cpu(es58x_fd_bittiming->bitrate));
+    netdev_vdbg(netdev, "tseg1 %s      = %d\n", type,
+            le16_to_cpu(es58x_fd_bittiming->tseg1));
+    netdev_vdbg(netdev, "tseg2 %s      = %d\n", type,
+            le16_to_cpu(es58x_fd_bittiming->tseg2));
+    netdev_vdbg(netdev, "brp %s        = %d\n", type,
+            le16_to_cpu(es58x_fd_bittiming->brp));
+    netdev_vdbg(netdev, "sjw %s        = %d\n", type,
+            le16_to_cpu(es58x_fd_bittiming->sjw));
+}
+
+static void es58x_fd_print_conf(struct net_device *netdev,
+                struct es58x_fd_tx_conf_msg *tx_conf_msg)
+{
+    es58x_fd_print_bittiming(netdev, &tx_conf_msg->nominal_bittiming,
+                 "nominal");
+    netdev_vdbg(netdev, "samples_per_bit    = %d\n",
+            tx_conf_msg->samples_per_bit);
+    netdev_vdbg(netdev, "sync_edge          = %d\n",
+            tx_conf_msg->sync_edge);
+    netdev_vdbg(netdev, "physical_layer     = %d\n",
+            tx_conf_msg->physical_layer);
+    netdev_vdbg(netdev, "self_reception     = %d\n",
+            tx_conf_msg->self_reception_mode);
+    netdev_vdbg(netdev, "ctrlmode           = %d\n", tx_conf_msg->ctrlmode);
+    netdev_vdbg(netdev, "canfd_enabled      = %d\n",
+            tx_conf_msg->canfd_enabled);
+    if (tx_conf_msg->canfd_enabled) {
+        es58x_fd_print_bittiming(netdev,
+                     &tx_conf_msg->data_bittiming, "data");
+        netdev_vdbg(netdev,
+                "Transmitter Delay Compensation        = %d\n",
+                tx_conf_msg->tdc);
+        netdev_vdbg(netdev,
+                "Transmitter Delay Compensation Offset = %d\n",
+                le16_to_cpu(tx_conf_msg->tdco));
+        netdev_vdbg(netdev,
+                "Transmitter Delay Compensation Filter = %d\n",
+                le16_to_cpu(tx_conf_msg->tdcf));
+    }
+}
+
+static void es58x_fd_convert_bittiming(struct es58x_fd_bittiming *es58x_fd_bt,
+                       struct can_bittiming *bt)
+{
+    /* The actual value set in the hardware registers is one less
+     * than the functional value.
+     */
+    const int offset = 1;
+
+    es58x_fd_bt->bitrate = cpu_to_le32(bt->bitrate);
+    es58x_fd_bt->tseg1 =
+        cpu_to_le16(bt->prop_seg + bt->phase_seg1 - offset);
+    es58x_fd_bt->tseg2 = cpu_to_le16(bt->phase_seg2 - offset);
+    es58x_fd_bt->brp = cpu_to_le16(bt->brp - offset);
+    es58x_fd_bt->sjw = cpu_to_le16(bt->sjw - offset);
+}
+
+static int es58x_fd_enable_channel(struct es58x_device *es58x_dev,
+                   int channel_idx)
+{
+    struct net_device *netdev = es58x_dev->netdev[channel_idx];
+    struct es58x_priv *priv = es58x_priv(netdev);
+    struct es58x_fd_tx_conf_msg tx_conf_msg = { 0 };
+    u32 ctrlmode;
+    bool is_can_fd = false;
+    size_t conf_len = 0;
+
+    es58x_fd_convert_bittiming(&tx_conf_msg.nominal_bittiming,
+                   &priv->can.bittiming);
+    ctrlmode = priv->can.ctrlmode;
+
+    tx_conf_msg.samples_per_bit =
+        ctrlmode & CAN_CTRLMODE_3_SAMPLES ?
+        ES58X_SAMPLES_PER_BIT_THREE : ES58X_SAMPLES_PER_BIT_ONE;
+    tx_conf_msg.sync_edge = ES58X_SYNC_EDGE_SINGLE;
+    tx_conf_msg.physical_layer = ES58X_PHYSICAL_LAYER_HIGH_SPEED;
+    tx_conf_msg.self_reception_mode = ES58X_SELF_RECEPTION_ON;
+
+    tx_conf_msg.ctrlmode |=
+        ctrlmode & CAN_CTRLMODE_LISTENONLY ?
+        ES58X_FD_CTRLMODE_PASSIVE : ES58X_FD_CTRLMODE_ACTIVE;
+
+    conf_len = ES58X_FD_CAN_CONF_LEN;
+    if (ctrlmode & CAN_CTRLMODE_FD) {
+        tx_conf_msg.ctrlmode |= ES58X_FD_CTRLMODE_FD_ISO;
+        is_can_fd = true;
+    } else if (ctrlmode & CAN_CTRLMODE_FD_NON_ISO) {
+        tx_conf_msg.ctrlmode |= ES58X_FD_CTRLMODE_FD_NON_ISO;
+        is_can_fd = true;
+    }
+    if (is_can_fd) {
+        struct can_bittiming *dbt = &priv->can.data_bittiming;
+        int tdco = 0;
+
+        conf_len = ES58X_FD_CANFD_CONF_LEN;
+
+        tx_conf_msg.canfd_enabled = !!is_can_fd;
+        es58x_fd_convert_bittiming(&tx_conf_msg.data_bittiming, dbt);
+
+        /* As specified in ISO 11898-1 section 11.3.3
+         * "Transmitter delay compensation" (TDC) is only
+         * applicable if data BRP is one or two.
+         */
+        tx_conf_msg.tdc = (dbt->brp == 1) || (dbt->brp == 2);
+        if (tx_conf_msg.tdc) {
+            /* Set the Transmitter Delay Compensation
+             * offset as the duration (in time quanta)
+             * from the start of the bit to the sample
+             * point.
+             */
+            tdco = can_bit_time(dbt) * dbt->sample_point / 1000;
+        }
+        tx_conf_msg.tdco = cpu_to_le16(min_t(u16, 127, tdco));
+        tx_conf_msg.tdcf = cpu_to_le16(0);
+    }
+    es58x_fd_print_conf(netdev, &tx_conf_msg);
+
+    return es58x_send_msg(es58x_dev, es58x_fd_cmd_type(netdev),
+                  ES58X_FD_CAN_CMD_ID_ENABLE_CHANNEL,
+                  &tx_conf_msg, conf_len, channel_idx);
+}
+
+static int es58x_fd_disable_channel(struct es58x_device *es58x_dev,
+                    int channel_idx)
+{
+    /* The type (ES58X_FD_CMD_TYPE_CAN or ES58X_FD_CMD_TYPE_CANFD) does
+     * not matter here.
+     */
+    return es58x_send_msg(es58x_dev, ES58X_FD_CMD_TYPE_CAN,
+                  ES58X_FD_CAN_CMD_ID_DISABLE_CHANNEL,
+                  ES58X_EMPTY_MSG, 0, channel_idx);
+}
+
+static int es58x_fd_reset_rx(struct es58x_device *es58x_dev, int channel_idx)
+{
+    struct net_device *netdev;
+    int ret;
+
+    ret = es58x_get_netdev(es58x_dev, channel_idx, &netdev);
+    if (ret)
+        return ret;
+
+    return es58x_send_msg(es58x_dev, es58x_fd_cmd_type(netdev),
+                  ES58X_FD_CAN_CMD_ID_RESET_RX, ES58X_EMPTY_MSG,
+                  0, channel_idx);
+}
+
+static int es58x_fd_reset_tx(struct es58x_device *es58x_dev, int channel_idx)
+{
+    struct net_device *netdev;
+    int ret;
+
+    ret = es58x_get_netdev(es58x_dev, channel_idx, &netdev);
+    if (ret)
+        return ret;
+
+    return es58x_send_msg(es58x_dev, es58x_fd_cmd_type(netdev),
+                  ES58X_FD_CAN_CMD_ID_RESET_TX, ES58X_EMPTY_MSG,
+                  0, channel_idx);
+}
+
+static int es58x_fd_get_timestamp(struct es58x_device *es58x_dev)
+{
+    return es58x_send_msg(es58x_dev, ES58X_FD_CMD_TYPE_DEVICE,
+                  ES58X_FD_DEV_CMD_ID_TIMESTAMP, ES58X_EMPTY_MSG,
+                  0, ES58X_CHANNEL_IDX_NA);
+}
+
+/* struct es58x_fd_nom_bittiming_const - Nominal bittiming constants.
+ *
+ * Nominal bittiming constants for ES582.1 and ES584.1 as specified in
+ * the microcontroller datasheet: "SAM E701/S70/V70/V71 Family"
+ * section 49.6.8 "MCAN Nominal Bit Timing and Prescaler Register"
+ * from Microchip.
+ *
+ * The values from the specification are the hardware register
+ * values. To convert them to the functional values, all ranges were
+ * incremented by 1 (e.g. range [0..n-1] changed to [1..n]).
+ */
+static const struct can_bittiming_const es58x_fd_nom_bittiming_const = {
+    .name = "ES582.1/ES584.1",
+    .tseg1_min = 2,
+    .tseg1_max = 256,
+    .tseg2_min = 2,
+    .tseg2_max = 128,
+    .sjw_max = 128,
+    .brp_min = 1,
+    .brp_max = 512,
+    .brp_inc = 1
+};
+
+/* struct es58x_fd_data_bittiming_const - Data bittiming constants.
+ *
+ * Data bittiming constants for ES582.1 and ES584.1 as specified in
+ * the microcontroller datasheet: "SAM E701/S70/V70/V71 Family"
+ * section 49.6.4 "MCAN Data Bit Timing and Prescaler Register" from
+ * Microchip.
+ */
+static const struct can_bittiming_const es58x_fd_data_bittiming_const = {
+    .name = "ES582.1/ES584.1",
+    .tseg1_min = 2,
+    .tseg1_max = 32,
+    .tseg2_min = 1,
+    .tseg2_max = 16,
+    .sjw_max = 8,
+    .brp_min = 1,
+    .brp_max = 32,
+    .brp_inc = 1
+};
+
+const struct es58x_parameters es58x_fd_param = {
+    .bittiming_const = &es58x_fd_nom_bittiming_const,
+    .data_bittiming_const = &es58x_fd_data_bittiming_const,
+    .bitrate_max = ES58X_MBPS(8),
+    .clock = {.freq = ES58X_MHZ(80)},
+    .ctrlmode_supported = CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY |
+        CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO |
+        CAN_CTRLMODE_CC_LEN8_DLC,
+    .tx_start_of_frame = 0xCEFA,    /* FACE in little endian */
+    .rx_start_of_frame = 0xFECA,    /* CAFE in little endian */
+    .tx_urb_cmd_max_len = ES58X_FD_TX_URB_CMD_MAX_LEN,
+    .rx_urb_cmd_max_len = ES58X_FD_RX_URB_CMD_MAX_LEN,
+    /* Size of internal device TX queue is 500.
+     *
+     * However, when reaching value around 278, the device's busy
+     * LED turns on and thus maximum value of 500 is never reached
+     * in practice. Also, when this value is too high, some error
+     * on the rx_loopback_msg were witnessed when the device is
+     * recovering from bus off.
+     *
+     * For above reasons, a value that would prevent the device
+     * from becoming busy was chosen. In practice, BQL would
+     * prevent the value from even getting closer to below
+     * maximum, so no impact on performance was measured.
+     */
+    .echo_skb_max = U8_MAX,
+#ifdef CONFIG_BQL
+    /* Empirical value. */
+    .dql_limit_min = ES58X_CAN_FRAME_BYTES_MAX * 15,
+#endif
+    .tx_bulk_max = ES58X_FD_TX_BULK_MAX,
+    .urb_cmd_header_len = ES58X_FD_URB_CMD_HEADER_LEN,
+    .rx_urb_max = ES58X_RX_URBS_MAX,
+    .tx_urb_max = ES58X_TX_URBS_MAX,
+    .channel_idx_offset = 0
+};
+
+const struct es58x_operators es58x_fd_ops = {
+    .get_msg_len = es58x_fd_get_msg_len,
+    .handle_urb_cmd = es58x_fd_handle_urb_cmd,
+    .fill_urb_header = es58x_fd_fill_urb_header,
+    .tx_can_msg = es58x_fd_tx_can_msg,
+    .set_bittiming = es58x_fd_set_bittiming,
+    .enable_channel = es58x_fd_enable_channel,
+    .disable_channel = es58x_fd_disable_channel,
+    .reset_rx = es58x_fd_reset_rx,
+    .reset_tx = es58x_fd_reset_tx,
+    .get_timestamp = es58x_fd_get_timestamp
+};
diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.h
b/drivers/net/can/usb/etas_es58x/es58x_fd.h
new file mode 100644
index 000000000000..3d3e84a2d933
--- /dev/null
+++ b/drivers/net/can/usb/etas_es58x/es58x_fd.h
@@ -0,0 +1,242 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
+ *
+ * File es58x_fd.h: Definitions and declarations specific to ETAS
+ * ES582.1 and ES584.1 (naming convention: we use the term "ES58X FD"
+ * when referring to those two variants together).
+ *
+ * Copyright (C) 2019 Robert Bosch Engineering and Business
+ * Solutions. All rights reserved.
+ * Copyright (C) 2020 ETAS K.K.. All rights reserved.
+ */
+
+#ifndef __ES58X_FD_H__
+#define __ES58X_FD_H__
+
+#include <linux/types.h>
+
+#define ES582_1_NUM_CAN_CH 2
+#define ES584_1_NUM_CAN_CH 1
+#define ES58X_FD_NUM_CAN_CH 2
+
+#define ES58X_FD_TX_BULK_MAX 100
+#define ES58X_FD_RX_BULK_MAX 100
+#define ES58X_FD_RX_LOOPBACK_BULK_MAX 100
+
+enum es58x_fd_cmd_type {
+    ES58X_FD_CMD_TYPE_CAN = 0x03,
+    ES58X_FD_CMD_TYPE_CANFD = 0x04,
+    ES58X_FD_CMD_TYPE_DEVICE = 0xFF
+};
+
+/* Command IDs for ES58X_FD_CMD_TYPE_{CAN,CANFD}. */
+enum es58x_fd_can_cmd_id {
+    ES58X_FD_CAN_CMD_ID_ENABLE_CHANNEL = 0x01,
+    ES58X_FD_CAN_CMD_ID_DISABLE_CHANNEL = 0x02,
+    ES58X_FD_CAN_CMD_ID_TX_MSG = 0x05,
+    ES58X_FD_CAN_CMD_ID_MSG_SELFRX_ACK = 0x07,
+    ES58X_FD_CAN_CMD_ID_RX_MSG = 0x10,
+    ES58X_FD_CAN_CMD_ID_ERROR_OR_EVENT_MSG = 0x11,
+    ES58X_FD_CAN_CMD_ID_RESET_RX = 0x20,
+    ES58X_FD_CAN_CMD_ID_RESET_TX = 0x21,
+    ES58X_FD_CAN_CMD_ID_TX_MSG_NO_ACK = 0x55
+};
+
+/* Command IDs for ES58X_FD_CMD_TYPE_DEVICE. */
+enum es58x_fd_dev_cmd_id {
+    ES58X_FD_DEV_CMD_ID_GETTIMETICKS = 0x01,
+    ES58X_FD_DEV_CMD_ID_TIMESTAMP = 0x02
+};
+
+/**
+ * enum es58x_fd_ctrlmode - Controller mode.
+ * @ES58X_FD_CTRLMODE_ACTIVE: send and receive messages.
+ * @ES58X_FD_CTRLMODE_PASSIVE: only receive messages (monitor). Do not
+ *    send anything, not even the acknowledgment bit.
+ * @ES58X_FD_CTRLMODE_FD_ISO: CAN-FD according to ISO11898-1.
+ * @ES58X_FD_CTRLMODE_FD_NON_ISO: follow Bosch CAN FD Specification
+ *    V1.0
+ * @ES58X_FD_CTRLMODE_DISABLE_PROTOCOL_EXCEPTION_HANDLING: How to
+ *    behave when CAN FD reserved bit is monitored as
+ *    dominant. (c.f. ISO 11898-1:2015, section 10.4.2.4 "Control
+ *    field", paragraph "r0 bit"). 0 (not disable = enable): send
+ *    error frame. 1 (disable): goes into bus integration mode
+ *    (c.f. below).
+ * @ES58X_FD_CTRLMODE_EDGE_FILTER_DURING_BUS_INTEGRATION: 0: Edge
+ *    filtering is disabled. 1: Edge filtering is enabled. Two
+ *    consecutive dominant bits required to detect an edge for hard
+ *    synchronization.
+ */
+enum es58x_fd_ctrlmode {
+    ES58X_FD_CTRLMODE_ACTIVE = 0,
+    ES58X_FD_CTRLMODE_PASSIVE = BIT(0),
+    ES58X_FD_CTRLMODE_FD_ISO = BIT(4),
+    ES58X_FD_CTRLMODE_FD_NON_ISO = BIT(5),
+    ES58X_FD_CTRLMODE_DISABLE_PROTOCOL_EXCEPTION_HANDLING = BIT(6),
+    ES58X_FD_CTRLMODE_EDGE_FILTER_DURING_BUS_INTEGRATION = BIT(7)
+};
+
+struct es58x_fd_bittiming {
+    __le32 bitrate;
+    __le16 tseg1;        /* range: [tseg1_min-1..tseg1_max-1] */
+    __le16 tseg2;        /* range: [tseg2_min-1..tseg2_max-1] */
+    __le16 brp;        /* range: [brp_min-1..brp_max-1] */
+    __le16 sjw;        /* range: [0..sjw_max-1] */
+} __packed;
+
+/**
+ * struct es58x_fd_tx_conf_msg - Channel configuration.
+ * @nominal_bittiming: Nominal bittiming.
+ * @samples_per_bit: type enum es58x_samples_per_bit.
+ * @sync_edge: type enum es58x_sync_edge.
+ * @physical_layer: type enum es58x_physical_layer.
+ * @self_reception_mode: type enum es58x_self_reception_mode.
+ * @ctrlmode: type enum es58x_fd_ctrlmode.
+ * @canfd_enabled: boolean (0: Classical CAN, 1: CAN and/or CANFD).
+ * @data_bittiming: Bittiming for flexible data-rate transmission.
+ * @tdc: Transmitter Delay Compensation switch (0: disabled, 1:
+ *    enabled). On very high bitrates, the delay between when the
+ *    bit is sent and received on the CANTX and CANRX pins of the
+ *    transceiver start to be significant enough for errors to occur
+ *    and thus need to be compensated.
+ * @tdco: Transmitter Delay Compensation Offset. Offset value, in time
+ *    quanta, defining the delay between the start of the bit
+ *    reception on the CANRX pin of the transceiver and the SSP
+ *    (Secondary Sample Point). Valid values: 0 to 127.
+ * @tdcf: Transmitter Delay Compensation Filter window. Defines the
+ *    minimum value for the SSP position, in time quanta. The
+ *    feature is enabled when TDCF is configured to a value greater
+ *    than TDCO. Valid values: 0 to 127.
+ *
+ * Please refer to the microcontroller datasheet: "SAM
+ * E701/S70/V70/V71 Family" section 49 "Controller Area Network
+ * (MCAN)" for additional information.
+ */
+struct es58x_fd_tx_conf_msg {
+    struct es58x_fd_bittiming nominal_bittiming;
+    u8 samples_per_bit;
+    u8 sync_edge;
+    u8 physical_layer;
+    u8 self_reception_mode;
+    u8 ctrlmode;
+    u8 canfd_enabled;
+    struct es58x_fd_bittiming data_bittiming;
+    u8 tdc;
+    __le16 tdco;
+    __le16 tdcf;
+} __packed;
+
+#define ES58X_FD_CAN_CONF_LEN                    \
+    (offsetof(struct es58x_fd_tx_conf_msg, canfd_enabled))
+#define ES58X_FD_CANFD_CONF_LEN (sizeof(struct es58x_fd_tx_conf_msg))
+
+struct es58x_fd_tx_can_msg {
+    u8 packet_idx;
+    __le32 can_id;
+    u8 flags;
+    union {
+        u8 dlc;        /* Only if cmd_id is ES58X_FD_CMD_TYPE_CAN */
+        u8 len;        /* Only if cmd_id is ES58X_FD_CMD_TYPE_CANFD */
+    } __packed;
+    u8 data[CANFD_MAX_DLEN];
+} __packed;
+
+#define ES58X_FD_CAN_TX_LEN                        \
+    (offsetof(struct es58x_fd_tx_can_msg, data[CAN_MAX_DLEN]))
+#define ES58X_FD_CANFD_TX_LEN (sizeof(struct es58x_fd_tx_can_msg))
+
+struct es58x_fd_rx_can_msg {
+    __le64 timestamp;
+    __le32 can_id;
+    u8 flags;
+    union {
+        u8 dlc;        /* Only if cmd_id is ES58X_FD_CMD_TYPE_CAN */
+        u8 len;        /* Only if cmd_id is ES58X_FD_CMD_TYPE_CANFD */
+    } __packed;
+    u8 data[CANFD_MAX_DLEN];
+} __packed;
+
+#define ES58X_FD_CAN_RX_LEN                        \
+    (offsetof(struct es58x_fd_rx_can_msg, data[CAN_MAX_DLEN]))
+#define ES58X_FD_CANFD_RX_LEN (sizeof(struct es58x_fd_rx_can_msg))
+
+struct es58x_fd_rx_loopback_msg {
+    __le64 timestamp;
+    u8 packet_idx;
+} __packed;
+
+struct es58x_fd_rx_event_msg {
+    __le64 timestamp;
+    __le32 can_id;
+    u8 flags;        /* type enum es58x_flag */
+    u8 error_type;        /* 0: event, 1: error */
+    u8 error_code;
+    u8 event_code;
+} __packed;
+
+struct es58x_fd_tx_ack_msg {
+    __le32 rx_cmd_ret_le32;    /* type enum es58x_cmd_ret_code_u32 */
+    __le16 tx_free_entries;    /* Number of remaining free entries in
the device TX queue */
+} __packed;
+
+/**
+ * struct es58x_fd_urb_cmd - Commands received from or sent to the
+ *    ES58X FD device.
+ * @SOF: Start of Frame.
+ * @cmd_type: Command Type (type: enum es58x_fd_cmd_type). The CRC
+ *    calculation starts at this position.
+ * @cmd_id: Command ID (type: enum es58x_fd_cmd_id).
+ * @channel_idx: Channel index starting at 0.
+ * @msg_len: Length of the message, excluding CRC (i.e. length of the
+ *    union).
+ * @tx_conf_msg: Channel configuration.
+ * @tx_can_msg_buf: Concatenation of Tx messages. Type is "u8[]"
+ *    instead of "struct es58x_fd_tx_msg[]" because the structure
+ *    has a flexible size.
+ * @rx_can_msg_buf: Concatenation Rx messages. Type is "u8[]" instead
+ *    of "struct es58x_fd_rx_msg[]" because the structure has a
+ *    flexible size.
+ * @rx_loopback_msg: Array of loopback messages.
+ * @rx_event_msg: Error or event message.
+ * @tx_ack_msg: Tx acknowledgment message.
+ * @timestamp: Timestamp reply.
+ * @rx_cmd_ret_le32: Rx 32 bits return code (type: enum
+ *    es58x_cmd_ret_code_u32).
+ * @raw_msg: Message raw payload.
+ * @reserved_for_crc16_do_not_use: The structure ends with a
+ *    CRC16. Because the structures in above union are of variable
+ *    lengths, we can not predict the offset of the CRC in
+ *    advance. Use functions es58x_get_crc() and es58x_set_crc() to
+ *    manipulate it.
+ */
+struct es58x_fd_urb_cmd {
+    __le16 SOF;
+    u8 cmd_type;
+    u8 cmd_id;
+    u8 channel_idx;
+    __le16 msg_len;
+
+    union {
+        struct es58x_fd_tx_conf_msg tx_conf_msg;
+        u8 tx_can_msg_buf[ES58X_FD_TX_BULK_MAX * ES58X_FD_CANFD_TX_LEN];
+        u8 rx_can_msg_buf[ES58X_FD_RX_BULK_MAX * ES58X_FD_CANFD_RX_LEN];
+        struct es58x_fd_rx_loopback_msg
+         rx_loopback_msg[ES58X_FD_RX_LOOPBACK_BULK_MAX];
+        struct es58x_fd_rx_event_msg rx_event_msg;
+        struct es58x_fd_tx_ack_msg tx_ack_msg;
+        __le64 timestamp;
+        __le32 rx_cmd_ret_le32;
+        u8 raw_msg[0];
+    } __packed;
+
+    __le16 reserved_for_crc16_do_not_use;
+} __packed;
+
+#define ES58X_FD_URB_CMD_HEADER_LEN (offsetof(struct
es58x_fd_urb_cmd, raw_msg))
+#define ES58X_FD_TX_URB_CMD_MAX_LEN                    \
+    ES58X_SIZEOF_URB_CMD(struct es58x_fd_urb_cmd, tx_can_msg_buf)
+#define ES58X_FD_RX_URB_CMD_MAX_LEN                    \
+    ES58X_SIZEOF_URB_CMD(struct es58x_fd_urb_cmd, rx_can_msg_buf)
+
+#endif /* __ES58X_FD_H__ */
-- 
2.26.2

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