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Date: Sun, 27 Nov 2022 20:02:43 +0100
From: Christoph Fritz <christoph.fritz@...dev.de>
To: Oliver Hartkopp <socketcan@...tkopp.net>,
Pavel Pisa <pisa@....felk.cvut.cz>,
Richard Weinberger <richard@....at>,
Andreas Lauser <andreas.lauser@...tion.io>,
Wolfgang Grandegger <wg@...ndegger.com>,
Marc Kleine-Budde <mkl@...gutronix.de>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Jonathan Corbet <corbet@....net>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] [RFC] can: Introduce LIN bus as CANFD abstraction
This patch adds a LIN bus abstraction ontop of CANFD. It is a glue
driver adapting CAN on one side while offering LIN abstraction on the
other side. So that upcoming LIN device drivers can make use of it.
Signed-off-by: Christoph Fritz <christoph.fritz@...dev.de>
---
drivers/net/can/Kconfig | 10 ++
drivers/net/can/Makefile | 1 +
drivers/net/can/lin.c | 181 +++++++++++++++++++++++++++++++
include/net/lin.h | 30 +++++
include/uapi/linux/can.h | 1 +
include/uapi/linux/can/netlink.h | 1 +
6 files changed, 224 insertions(+)
create mode 100644 drivers/net/can/lin.c
create mode 100644 include/net/lin.h
diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index 3048ad77edb3..d091994ea4fe 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -152,6 +152,16 @@ config CAN_KVASER_PCIEFD
Kvaser Mini PCI Express HS v2
Kvaser Mini PCI Express 2xHS v2
+config CAN_LIN
+ tristate "LIN mode support"
+ help
+ This is a glue driver for LIN-BUS support.
+
+ The local interconnect (LIN) bus is a simple bus with a feature
+ subset of CAN. It is often combined with CAN for simple controls.
+
+ Actual device drivers need to be enabled too.
+
config CAN_SLCAN
tristate "Serial / USB serial CAN Adaptors (slcan)"
depends on TTY
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index 61c75ce9d500..9114d9e97c0c 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_CAN_GRCAN) += grcan.o
obj-$(CONFIG_CAN_IFI_CANFD) += ifi_canfd/
obj-$(CONFIG_CAN_JANZ_ICAN3) += janz-ican3.o
obj-$(CONFIG_CAN_KVASER_PCIEFD) += kvaser_pciefd.o
+obj-$(CONFIG_CAN_LIN) += lin.o
obj-$(CONFIG_CAN_MSCAN) += mscan/
obj-$(CONFIG_CAN_M_CAN) += m_can/
obj-$(CONFIG_CAN_PEAK_PCIEFD) += peak_canfd/
diff --git a/drivers/net/can/lin.c b/drivers/net/can/lin.c
new file mode 100644
index 000000000000..25eaccc18ab6
--- /dev/null
+++ b/drivers/net/can/lin.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 hexDEV GmbH
+ */
+#include <linux/can/core.h>
+#include <linux/can/dev.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <net/lin.h>
+
+static void lin_tx_work_handler(struct work_struct *ws)
+{
+ struct lin_device *priv = container_of(ws, struct lin_device,
+ tx_work);
+ struct net_device *net = priv->net;
+ struct device *dev = priv->dev;
+ struct canfd_frame *frame;
+ u8 id, n;
+
+ priv->tx_busy = true;
+
+ frame = (struct canfd_frame *)priv->tx_skb->data;
+ id = (u8)frame->can_id & 0xff;
+ n = frame->len;
+
+ priv->lindev_ops->ldo_tx(dev, id, n, frame->data);
+ priv->tx_busy = false;
+ netif_wake_queue(net);
+}
+
+static netdev_tx_t lin_start_xmit(struct sk_buff *skb,
+ struct net_device *netdev)
+{
+ struct lin_device *priv = netdev_priv(netdev);
+
+ if (priv->tx_busy)
+ return NETDEV_TX_BUSY;
+
+ netif_stop_queue(netdev);
+ priv->tx_skb = skb;
+ queue_work(priv->wq, &priv->tx_work);
+
+ return NETDEV_TX_OK;
+}
+
+static int lin_open(struct net_device *netdev)
+{
+ struct lin_device *priv = netdev_priv(netdev);
+ int ret;
+
+ priv->tx_busy = false;
+
+ ret = open_candev(netdev);
+ if (ret)
+ return ret;
+
+ netif_wake_queue(netdev);
+
+ return 0;
+}
+
+static int lin_stop(struct net_device *net)
+{
+ close_candev(net);
+
+ return 0;
+}
+
+static const struct net_device_ops lin_netdev_ops = {
+ .ndo_open = lin_open,
+ .ndo_stop = lin_stop,
+ .ndo_start_xmit = lin_start_xmit,
+ .ndo_change_mtu = can_change_mtu,
+};
+
+int lin_rx(struct lin_device *priv, u8 id, u8 n, u8 *data, u8 checksum)
+{
+ struct net_device *ndev = priv->net;
+ struct net_device_stats *stats = &ndev->stats;
+ struct canfd_frame *cfd;
+ struct sk_buff *skb;
+
+ skb = alloc_canfd_skb(ndev, &cfd);
+ if (unlikely(!skb)) {
+ stats->rx_dropped++;
+ return -ENOMEM;
+ }
+
+ cfd->flags = CANFD_LIN;
+ cfd->can_id = id;
+ cfd->len = n + 1; /* n of data + checksum */
+ memcpy(cfd->data, data, n);
+ cfd->data[n] = checksum;
+
+ stats->rx_bytes += cfd->len;
+ stats->rx_packets++;
+
+ netif_receive_skb(skb);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lin_rx);
+
+static int lin_set_bittiming(struct net_device *netdev)
+{
+ struct lin_device *priv = netdev_priv(netdev);
+ struct device *dev = priv->dev;
+ int ret;
+
+ ret = priv->lindev_ops->update_bitrate(dev, priv->can.bittiming.bitrate);
+
+ return ret;
+}
+
+static const u32 lin_bitrate[] = { 2400, 4800, 9600, 19200 };
+
+struct lin_device *register_lin(struct device *dev,
+ const struct lin_device_ops *ldops)
+{
+ struct net_device *ndev;
+ struct lin_device *priv;
+ int ret;
+
+ ndev = alloc_candev(sizeof(struct lin_device), 1);
+ if (!ndev)
+ return NULL;
+
+ ndev->netdev_ops = &lin_netdev_ops;
+ ndev->flags |= IFF_ECHO;
+ ndev->mtu = CANFD_MTU;
+
+ priv = netdev_priv(ndev);
+ priv->lindev_ops = ldops;
+ priv->can.bittiming.bitrate = 9600;
+ priv->can.ctrlmode_supported = CAN_CTRLMODE_LIN;
+ priv->can.bitrate_const = lin_bitrate;
+ priv->can.bitrate_const_cnt = ARRAY_SIZE(lin_bitrate);
+ priv->can.do_set_bittiming = lin_set_bittiming;
+ priv->net = ndev;
+ priv->dev = dev;
+
+ SET_NETDEV_DEV(ndev, dev);
+
+ ret = register_candev(ndev);
+ if (ret)
+ goto exit_free;
+
+ priv->wq = alloc_workqueue(dev_name(dev), WQ_FREEZABLE | WQ_MEM_RECLAIM,
+ 0);
+ if (!priv->wq) {
+ ret = -ENOMEM;
+ goto exit_free;
+ }
+ INIT_WORK(&priv->tx_work, lin_tx_work_handler);
+
+ netdev_info(ndev, "LIN initialized.\n");
+
+ return priv;
+
+exit_free:
+ free_candev(ndev);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(register_lin);
+
+void unregister_lin(struct lin_device *priv)
+{
+ unregister_candev(priv->net);
+
+ destroy_workqueue(priv->wq);
+ priv->wq = NULL;
+
+ free_candev(priv->net);
+}
+EXPORT_SYMBOL_GPL(unregister_lin);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christoph Fritz <christoph.fritz@...dev.de>");
+MODULE_DESCRIPTION("LIN bus to CAN glue driver");
diff --git a/include/net/lin.h b/include/net/lin.h
new file mode 100644
index 000000000000..d3264844ce16
--- /dev/null
+++ b/include/net/lin.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef _NET_LIN_H_
+#define _NET_LIN_H_
+
+#include <linux/can/dev.h>
+#include <linux/device.h>
+
+struct lin_device_ops {
+ int (*ldo_tx)(struct device *dev, u8 id, u8 n, u8 *data);
+ int (*update_bitrate)(struct device *dev, u16 bitrate);
+};
+
+struct lin_device {
+ struct can_priv can;
+ struct net_device *net;
+ const struct lin_device_ops *lindev_ops;
+ struct device *dev;
+ struct workqueue_struct *wq;
+ struct work_struct tx_work;
+ bool tx_busy;
+ struct sk_buff *tx_skb;
+};
+
+int lin_rx(struct lin_device *dev, u8 id, u8 n, u8 *bytes, u8 checksum);
+
+struct lin_device *register_lin(struct device *dev,
+ const struct lin_device_ops *ldops);
+void unregister_lin(struct lin_device *lbd);
+
+#endif /* _NET_LIN_H_ */
diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h
index 90801ada2bbe..8596f9b23c68 100644
--- a/include/uapi/linux/can.h
+++ b/include/uapi/linux/can.h
@@ -147,6 +147,7 @@ struct can_frame {
#define CANFD_BRS 0x01 /* bit rate switch (second bitrate for payload data) */
#define CANFD_ESI 0x02 /* error state indicator of the transmitting node */
#define CANFD_FDF 0x04 /* mark CAN FD for dual use of struct canfd_frame */
+#define CANFD_LIN 0x08 /* indicate LIN mode */
/**
* struct canfd_frame - CAN flexible data rate frame structure
diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h
index 02ec32d69474..d65a24b2aa3c 100644
--- a/include/uapi/linux/can/netlink.h
+++ b/include/uapi/linux/can/netlink.h
@@ -103,6 +103,7 @@ struct can_ctrlmode {
#define CAN_CTRLMODE_CC_LEN8_DLC 0x100 /* Classic CAN DLC option */
#define CAN_CTRLMODE_TDC_AUTO 0x200 /* CAN transiver automatically calculates TDCV */
#define CAN_CTRLMODE_TDC_MANUAL 0x400 /* TDCV is manually set up by user */
+#define CAN_CTRLMODE_LIN 0x800 /* LIN BUS mode */
/*
* CAN device statistics
--
2.30.2
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