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Message-ID: <CAMZ6RqJbjoApwZbiivbvJRYQyBWfWXG4azmwuXGaicrMq0Lozg@mail.gmail.com>
Date: Fri, 12 May 2023 18:53:53 +0900
From: Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To: Mikhail Golubev-Ciuchea <Mikhail.Golubev-Ciuchea@...nsynergy.com>
Cc: virtio-dev@...ts.oasis-open.org, linux-can@...r.kernel.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
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>,
"Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
Damir Shaikhutdinov <Damir.Shaikhutdinov@...nsynergy.com>,
Harald Mommer <harald.mommer@...nsynergy.com>
Subject: Re: [RFC PATCH v3] can: virtio: Initial virtio CAN driver.
Hi Mikhail,
Thanks for your patch. Do you have any plans for CAN error reporting
aside from the bus off? (e.g. can error-active, can error-passive, bit
errors...)
On Fri. 12 May 2023 at 00:18, Mikhail Golubev-Ciuchea
<Mikhail.Golubev-Ciuchea@...nsynergy.com> wrote:
> From: Harald Mommer <harald.mommer@...nsynergy.com>
>
> - CAN Control
>
> - "ip link set up can0" starts the virtual CAN controller,
> - "ip link set up can0" stops the virtual CAN controller
>
> - CAN RX
>
> Receive CAN frames. CAN frames can be standard or extended, classic or
> CAN FD. Classic CAN RTR frames are supported.
>
> - CAN TX
>
> Send CAN frames. CAN frames can be standard or extended, classic or
> CAN FD. Classic CAN RTR frames are supported.
>
> - CAN BusOff indication
>
> CAN BusOff is handled by a bit in the configuration space.
>
> Signed-off-by: Harald Mommer <Harald.Mommer@...nsynergy.com>
> Signed-off-by: Mikhail Golubev-Ciuchea <Mikhail.Golubev-Ciuchea@...nsynergy.com>
> Co-developed-by: Marc Kleine-Budde <mkl@...gutronix.de>
> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
> Cc: Damir Shaikhutdinov <Damir.Shaikhutdinov@...nsynergy.com>
> ---
>
> V3:
> * Incorporate patch "[PATCH] can: virtio-can: cleanups" from
> https://lore.kernel.org/all/20230424-footwear-daily-9339bd0ec428-mkl@pengutronix.de/
> * Add missing can_free_echo_skb()
> * Replace home-brewed ID allocator with the standard one from kernel
> * Simplify flow control
> * Tested with https://github.com/OpenSynergy/qemu/tree/virtio-can-spec-rfc-v3
>
> V2:
> * Remove the event indication queue and use the config space instead, to
> indicate a bus off condition
> * Rework RX and TX messages having a length field and some more fields for CAN
> EXT
> * Fix CAN_EFF_MASK comparison
> * Remove MISRA style code (e.g. '! = 0u')
> * Remove priorities leftovers
> * Remove BUGONs
> * Based on virtio can spec RFCv3
> * Tested with https://github.com/OpenSynergy/qemu/tree/virtio-can-spec-rfc-v3
>
> MAINTAINERS | 7 +
> drivers/net/can/Kconfig | 12 +
> drivers/net/can/Makefile | 3 +-
> drivers/net/can/virtio_can.c | 1000 +++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_can.h | 71 +++
> 5 files changed, 1092 insertions(+), 1 deletion(-)
> create mode 100644 drivers/net/can/virtio_can.c
> create mode 100644 include/uapi/linux/virtio_can.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7e0b87d5aa2e..ca45950c8364 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22246,6 +22246,13 @@ F: drivers/vhost/scsi.c
> F: include/uapi/linux/virtio_blk.h
> F: include/uapi/linux/virtio_scsi.h
>
> +VIRTIO CAN DRIVER
> +M: "Harald Mommer" <harald.mommer@...nsynergy.com>
> +L: linux-can@...r.kernel.org
> +S: Maintained
> +F: drivers/net/can/virtio_can.c
> +F: include/uapi/linux/virtio_can.h
> +
> VIRTIO CONSOLE DRIVER
> M: Amit Shah <amit@...nel.org>
> L: virtualization@...ts.linux-foundation.org
> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> index 3ceccafd701b..ee47fdff2252 100644
> --- a/drivers/net/can/Kconfig
> +++ b/drivers/net/can/Kconfig
> @@ -210,6 +210,18 @@ config CAN_XILINXCAN
> Xilinx CAN driver. This driver supports both soft AXI CAN IP and
> Zynq CANPS IP.
>
> +config CAN_VIRTIO_CAN
> + depends on VIRTIO
> + tristate "Virtio CAN device support"
> + default n
> + help
> + Say Y here if you want to support for Virtio CAN.
Broken grammar.
Do either
Say Y here if you want to add support for Virtio CAN.
or:
Say Y here if you want to support Virtio CAN devices.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called virtio-can.
> +
> + If unsure, say N.
> +
> source "drivers/net/can/c_can/Kconfig"
> source "drivers/net/can/cc770/Kconfig"
> source "drivers/net/can/ctucanfd/Kconfig"
> diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> index ff8f76295d13..19314adaff59 100644
> --- a/drivers/net/can/Makefile
> +++ b/drivers/net/can/Makefile
> @@ -17,8 +17,8 @@ obj-$(CONFIG_CAN_AT91) += at91_can.o
> obj-$(CONFIG_CAN_BXCAN) += bxcan.o
> obj-$(CONFIG_CAN_CAN327) += can327.o
> obj-$(CONFIG_CAN_CC770) += cc770/
> -obj-$(CONFIG_CAN_C_CAN) += c_can/
> obj-$(CONFIG_CAN_CTUCANFD) += ctucanfd/
> +obj-$(CONFIG_CAN_C_CAN) += c_can/
This reordering is unrelated to this patch goal. Please send it as a
separate patch.
> obj-$(CONFIG_CAN_FLEXCAN) += flexcan/
> obj-$(CONFIG_CAN_GRCAN) += grcan.o
> obj-$(CONFIG_CAN_IFI_CANFD) += ifi_canfd/
> @@ -30,6 +30,7 @@ obj-$(CONFIG_CAN_PEAK_PCIEFD) += peak_canfd/
> obj-$(CONFIG_CAN_SJA1000) += sja1000/
> obj-$(CONFIG_CAN_SUN4I) += sun4i_can.o
> obj-$(CONFIG_CAN_TI_HECC) += ti_hecc.o
> +obj-$(CONFIG_CAN_VIRTIO_CAN) += virtio_can.o
> obj-$(CONFIG_CAN_XILINXCAN) += xilinx_can.o
>
> subdir-ccflags-$(CONFIG_CAN_DEBUG_DEVICES) += -DDEBUG
> diff --git a/drivers/net/can/virtio_can.c b/drivers/net/can/virtio_can.c
> new file mode 100644
> index 000000000000..ebc3394276d6
> --- /dev/null
> +++ b/drivers/net/can/virtio_can.c
> @@ -0,0 +1,1000 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * CAN bus driver for the Virtio CAN controller
> + * Copyright (C) 2021-2023 OpenSynergy GmbH
> + */
> +
> +#include <linux/atomic.h>
> +#include <linux/idr.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/netdevice.h>
> +#include <linux/stddef.h>
> +#include <linux/can/dev.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_ring.h>
> +#include <linux/virtio_can.h>
> +
> +/* CAN device queues */
> +#define VIRTIO_CAN_QUEUE_TX 0 /* Driver side view! The device receives here */
> +#define VIRTIO_CAN_QUEUE_RX 1 /* Driver side view! The device transmits here */
> +#define VIRTIO_CAN_QUEUE_CONTROL 2
> +#define VIRTIO_CAN_QUEUE_COUNT 3
> +
> +#define CAN_KNOWN_FLAGS \
> + (VIRTIO_CAN_FLAGS_EXTENDED |\
> + VIRTIO_CAN_FLAGS_FD |\
> + VIRTIO_CAN_FLAGS_RTR)
> +
> +/* Max. number of in flight TX messages */
> +#define VIRTIO_CAN_ECHO_SKB_MAX 128
> +
> +struct virtio_can_tx {
> + struct list_head list;
> + unsigned int putidx;
> + struct virtio_can_tx_out tx_out;
> + struct virtio_can_tx_in tx_in;
I am still waiting for your answer on my previous comment here:
https://lore.kernel.org/linux-can/CAMZ6Rq+RjOHaGx-7GLsj-PNAcHd=nGd=JERddqw4FWbNN3sAXA@mail.gmail.com/
> +};
> +
> +/* virtio_can private data structure */
> +struct virtio_can_priv {
> + struct can_priv can; /* must be the first member */
> + /* NAPI for RX messages */
> + struct napi_struct napi;
> + /* NAPI for TX messages */
> + struct napi_struct napi_tx;
> + /* The network device we're associated with */
> + struct net_device *dev;
> + /* The virtio device we're associated with */
> + struct virtio_device *vdev;
> + /* The virtqueues */
> + struct virtqueue *vqs[VIRTIO_CAN_QUEUE_COUNT];
> + /* I/O callback function pointers for the virtqueues */
> + vq_callback_t *io_callbacks[VIRTIO_CAN_QUEUE_COUNT];
> + /* Lock for TX operations */
> + spinlock_t tx_lock;
> + /* Control queue lock. Defensive programming, may be not needed */
> + struct mutex ctrl_lock;
> + /* Wait for control queue processing without polling */
> + struct completion ctrl_done;
> + /* List of virtio CAN TX message */
> + struct list_head tx_list;
> + /* Array of receive queue messages */
> + struct virtio_can_rx rpkt[128];
> + /* Those control queue messages cannot live on the stack! */
> + struct virtio_can_control_out cpkt_out;
> + struct virtio_can_control_in cpkt_in;
> + /* Data to get and maintain the putidx for local TX echo */
> + struct ida tx_putidx_ida;
> + /* In flight TX messages */
> + atomic_t tx_inflight;
> + /* BusOff pending. Reset after successful indication to upper layer */
> + bool busoff_pending;
> +};
> +
> +/* Function copied from virtio_net.c */
> +static void virtqueue_napi_schedule(struct napi_struct *napi,
> + struct virtqueue *vq)
> +{
> + if (napi_schedule_prep(napi)) {
> + virtqueue_disable_cb(vq);
> + __napi_schedule(napi);
> + }
> +}
> +
> +/* Function copied from virtio_net.c */
> +static void virtqueue_napi_complete(struct napi_struct *napi,
> + struct virtqueue *vq, int processed)
> +{
> + int opaque;
> +
> + opaque = virtqueue_enable_cb_prepare(vq);
> + if (napi_complete_done(napi, processed)) {
> + if (unlikely(virtqueue_poll(vq, opaque)))
> + virtqueue_napi_schedule(napi, vq);
> + } else {
> + virtqueue_disable_cb(vq);
> + }
> +}
> +
> +static void virtio_can_free_candev(struct net_device *ndev)
> +{
> + struct virtio_can_priv *priv = netdev_priv(ndev);
> +
> + ida_destroy(&priv->tx_putidx_ida);
> + free_candev(ndev);
> +}
> +
> +static int virtio_can_alloc_tx_idx(struct virtio_can_priv *priv)
> +{
> + int tx_idx;
> +
> + tx_idx = ida_alloc_range(&priv->tx_putidx_ida, 0,
> + priv->can.echo_skb_max - 1, GFP_KERNEL);
> + if (tx_idx >= 0)
> + atomic_add(1, &priv->tx_inflight);
> +
> + return tx_idx;
> +}
> +
> +static void virtio_can_free_tx_idx(struct virtio_can_priv *priv,
> + unsigned int idx)
> +{
> + ida_free(&priv->tx_putidx_ida, idx);
> + atomic_sub(1, &priv->tx_inflight);
> +}
> +
> +/* Create a scatter-gather list representing our input buffer and put
> + * it in the queue.
> + *
> + * Callers should take appropriate locks.
> + */
> +static int virtio_can_add_inbuf(struct virtqueue *vq, void *buf,
> + unsigned int size)
> +{
> + struct scatterlist sg[1];
> + int ret;
> +
> + sg_init_one(sg, buf, size);
> +
> + ret = virtqueue_add_inbuf(vq, sg, 1, buf, GFP_ATOMIC);
> + virtqueue_kick(vq);
> + if (ret == 0)
> + ret = vq->num_free;
> + return ret;
> +}
> +
> +/* Send a control message with message type either
> + *
> + * - VIRTIO_CAN_SET_CTRL_MODE_START or
> + * - VIRTIO_CAN_SET_CTRL_MODE_STOP.
> + *
> + * Unlike AUTOSAR CAN Driver Can_SetControllerMode() there is no requirement
> + * for this Linux driver to have an asynchronous implementation of the mode
> + * setting function so in order to keep things simple the function is
> + * implemented as synchronous function. Design pattern is
> + * virtio_console.c/__send_control_msg() & virtio_net.c/virtnet_send_command().
> + */
> +static u8 virtio_can_send_ctrl_msg(struct net_device *ndev, u16 msg_type)
> +{
> + struct virtio_can_priv *priv = netdev_priv(ndev);
> + struct device *dev = &priv->vdev->dev;
> + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL];
> + struct scatterlist sg_out[1];
> + struct scatterlist sg_in[1];
> + struct scatterlist *sgs[2];
> + int err;
> + unsigned int len;
> +
> + /* The function may be serialized by rtnl lock. Not sure.
> + * Better safe than sorry.
> + */
> + mutex_lock(&priv->ctrl_lock);
> +
> + priv->cpkt_out.msg_type = cpu_to_le16(msg_type);
> + sg_init_one(&sg_out[0], &priv->cpkt_out, sizeof(priv->cpkt_out));
> + sg_init_one(&sg_in[0], &priv->cpkt_in, sizeof(priv->cpkt_in));
> + sgs[0] = sg_out;
> + sgs[1] = sg_in;
> +
> + err = virtqueue_add_sgs(vq, sgs, 1u, 1u, priv, GFP_ATOMIC);
> + if (err != 0) {
if (err) {
> + /* Not expected to happen */
> + dev_err(dev, "%s(): virtqueue_add_sgs() failed\n", __func__);
> + }
> +
> + if (!virtqueue_kick(vq)) {
> + /* Not expected to happen */
> + dev_err(dev, "%s(): Kick failed\n", __func__);
> + }
> +
> + while (!virtqueue_get_buf(vq, &len) && !virtqueue_is_broken(vq))
> + wait_for_completion(&priv->ctrl_done);
> +
> + mutex_unlock(&priv->ctrl_lock);
> +
> + return priv->cpkt_in.result;
> +}
> +
> +static void virtio_can_start(struct net_device *ndev)
> +{
> + struct virtio_can_priv *priv = netdev_priv(ndev);
> + u8 result;
> +
> + result = virtio_can_send_ctrl_msg(ndev, VIRTIO_CAN_SET_CTRL_MODE_START);
> + if (result != VIRTIO_CAN_RESULT_OK) {
> + /* Not expected to happen */
> + netdev_err(ndev, "CAN controller start failed\n");
> + }
> +
> + priv->busoff_pending = false;
> + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> + /* Switch carrier on if device was not connected to the bus */
> + if (!netif_carrier_ok(ndev))
> + netif_carrier_on(ndev);
> +}
> +
> +/* See also m_can.c/m_can_set_mode()
> + *
> + * It is interesting that not only the M-CAN implementation but also all other
> + * implementations I looked into only support CAN_MODE_START.
> + * That CAN_MODE_SLEEP is frequently not found to be supported anywhere did not
> + * come not as surprise but that CAN_MODE_STOP is also never supported was one.
> + * The function is accessible via the method pointer do_set_mode in
> + * struct can_priv. As usual no documentation there.
> + * May not play any role as grepping through the code did not reveal any place
> + * from where the method is actually called.
> + */
> +static int virtio_can_set_mode(struct net_device *dev, enum can_mode mode)
> +{
> + switch (mode) {
> + case CAN_MODE_START:
> + virtio_can_start(dev);
> + netif_wake_queue(dev);
> + break;
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + return 0;
> +}
> +
> +/* Called by issuing "ip link set up can0" */
> +static int virtio_can_open(struct net_device *dev)
> +{
> + /* start the virtio_can controller */
> + virtio_can_start(dev);
> +
> + /* RX and TX napi were already enabled in virtio_can_probe() */
> + netif_start_queue(dev);
> +
> + return 0;
> +}
> +
> +static void virtio_can_stop(struct net_device *ndev)
> +{
> + struct virtio_can_priv *priv = netdev_priv(ndev);
> + struct device *dev = &priv->vdev->dev;
> + u8 result;
> +
> + result = virtio_can_send_ctrl_msg(ndev, VIRTIO_CAN_SET_CTRL_MODE_STOP);
> + if (result != VIRTIO_CAN_RESULT_OK)
> + dev_err(dev, "CAN controller stop failed\n");
> +
> + priv->busoff_pending = false;
> + priv->can.state = CAN_STATE_STOPPED;
> +
> + /* Switch carrier off if device was connected to the bus */
> + if (netif_carrier_ok(ndev))
> + netif_carrier_off(ndev);
> +}
> +
> +static int virtio_can_close(struct net_device *dev)
> +{
> + netif_stop_queue(dev);
> + /* Keep RX napi active to allow dropping of pending RX CAN messages,
> + * keep TX napi active to allow processing of cancelled CAN messages
> + */
> + virtio_can_stop(dev);
> + close_candev(dev);
> +
> + return 0;
> +}
> +
> +static netdev_tx_t virtio_can_start_xmit(struct sk_buff *skb,
> + struct net_device *dev)
> +{
> + struct virtio_can_priv *priv = netdev_priv(dev);
> + struct canfd_frame *cf = (struct canfd_frame *)skb->data;
> + struct virtio_can_tx *can_tx_msg;
> + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_TX];
> + struct scatterlist sg_out[1];
> + struct scatterlist sg_in[1];
> + struct scatterlist *sgs[2];
Instead declaring two times an array of 1, can we do:
struct scatterlist sgs[2];
and then use sgs[0] for out and sgs[1] for in?
Or, if you really want to keep sg_out and sg_in, at least do:
struct scatterlist sg_out, sg_in;
struct scatterlist *sgs[] = {&sg_out, &sg_in};
N.B. The same comment also applies to the other places where you are
doing some sg[1] declarations.
> + unsigned long flags;
> + u32 can_flags;
> + int err;
> + int putidx;
> + netdev_tx_t xmit_ret = NETDEV_TX_OK;
> + const unsigned int hdr_size = offsetof(struct virtio_can_tx_out, sdu);
> +
> + if (can_dev_dropped_skb(dev, skb))
> + goto kick; /* No way to return NET_XMIT_DROP here */
> +
> + /* No local check for CAN_RTR_FLAG or FD frame against negotiated
> + * features. The device will reject those anyway if not supported.
> + */
> +
> + can_tx_msg = kzalloc(sizeof(*can_tx_msg), GFP_ATOMIC);
> + if (!can_tx_msg)
> + goto kick; /* No way to return NET_XMIT_DROP here */
> +
> + can_tx_msg->tx_out.msg_type = cpu_to_le16(VIRTIO_CAN_TX);
> + can_flags = 0;
> +
> + if (cf->can_id & CAN_EFF_FLAG) {
> + can_flags |= VIRTIO_CAN_FLAGS_EXTENDED;
> + can_tx_msg->tx_out.can_id = cpu_to_le32(cf->can_id & CAN_EFF_MASK);
> + } else {
> + can_tx_msg->tx_out.can_id = cpu_to_le32(cf->can_id & CAN_SFF_MASK);
> + }
> + if (cf->can_id & CAN_RTR_FLAG)
> + can_flags |= VIRTIO_CAN_FLAGS_RTR;
> + else
> + memcpy(can_tx_msg->tx_out.sdu, cf->data, cf->len);
> + if (can_is_canfd_skb(skb))
> + can_flags |= VIRTIO_CAN_FLAGS_FD;
> +
> + can_tx_msg->tx_out.flags = cpu_to_le32(can_flags);
> + can_tx_msg->tx_out.length = cpu_to_le16(cf->len);
> +
> + /* Prepare sending of virtio message */
> + sg_init_one(&sg_out[0], &can_tx_msg->tx_out, hdr_size + cf->len);
> + sg_init_one(&sg_in[0], &can_tx_msg->tx_in, sizeof(can_tx_msg->tx_in));
> + sgs[0] = sg_out;
> + sgs[1] = sg_in;
> +
> + putidx = virtio_can_alloc_tx_idx(priv);
> +
> + if (unlikely(putidx < 0)) {
> + netif_stop_queue(dev);
> + kfree(can_tx_msg);
> + netdev_warn(dev, "TX: Stop queue, no putidx available\n");
ida_alloc_range() can also return -ENOMEM. So the error is not
necessarily because of no putidx available. Maybe better to print the
error message (with %pe to show the mnemotechnic).
> + xmit_ret = NETDEV_TX_BUSY;
> + goto kick;
> + }
> +
> + can_tx_msg->putidx = (unsigned int)putidx;
> +
> + /* Protect list operation */
> + spin_lock_irqsave(&priv->tx_lock, flags);
> + list_add_tail(&can_tx_msg->list, &priv->tx_list);
> + spin_unlock_irqrestore(&priv->tx_lock, flags);
> +
> + /* Push loopback echo. Will be looped back on TX interrupt/TX NAPI */
> + can_put_echo_skb(skb, dev, can_tx_msg->putidx, 0);
> +
> + /* Protect queue and list operations */
> + spin_lock_irqsave(&priv->tx_lock, flags);
> + err = virtqueue_add_sgs(vq, sgs, 1u, 1u, can_tx_msg, GFP_ATOMIC);
> + if (err != 0) { /* unlikely when vq->num_free was considered */
> + list_del(&can_tx_msg->list);
> + can_free_echo_skb(dev, can_tx_msg->putidx, NULL);
> + virtio_can_free_tx_idx(priv, can_tx_msg->putidx);
> + spin_unlock_irqrestore(&priv->tx_lock, flags);
> + netif_stop_queue(dev);
> + kfree(can_tx_msg);
> + if (err == -ENOSPC)
> + netdev_dbg(dev, "TX: Stop queue, no space left\n");
> + else
> + netdev_warn(dev, "TX: Stop queue, reason = %d\n", err);
> + xmit_ret = NETDEV_TX_BUSY;
> + goto kick;
> + }
> +
> + /* Normal queue stop when no transmission slots are left */
> + if (atomic_read(&priv->tx_inflight) >= priv->can.echo_skb_max ||
> + vq->num_free == 0 || (vq->num_free < 2 &&
Replace the Magic number 2 with a #define.
> + !virtio_has_feature(vq->vdev, VIRTIO_RING_F_INDIRECT_DESC))) {
> + netif_stop_queue(dev);
> + netdev_dbg(dev, "TX: Normal stop queue\n");
> + }
> +
> + spin_unlock_irqrestore(&priv->tx_lock, flags);
> +
> +kick:
> + if (netif_queue_stopped(dev) || !netdev_xmit_more()) {
> + if (!virtqueue_kick(vq))
> + netdev_err(dev, "%s(): Kick failed\n", __func__);
> + }
> +
> + return xmit_ret;
> +}
> +
> +static const struct net_device_ops virtio_can_netdev_ops = {
> + .ndo_open = virtio_can_open,
> + .ndo_stop = virtio_can_close,
> + .ndo_start_xmit = virtio_can_start_xmit,
> + .ndo_change_mtu = can_change_mtu,
> +};
> +
> +static int register_virtio_can_dev(struct net_device *dev)
> +{
> + dev->flags |= IFF_ECHO; /* we support local echo */
> + dev->netdev_ops = &virtio_can_netdev_ops;
> +
> + return register_candev(dev);
> +}
> +
> +/* Compare with m_can.c/m_can_echo_tx_event() */
> +static int virtio_can_read_tx_queue(struct virtqueue *vq)
> +{
> + struct virtio_can_priv *can_priv = vq->vdev->priv;
> + struct net_device *dev = can_priv->dev;
> + struct net_device_stats *stats = &dev->stats;
> + struct virtio_can_tx *can_tx_msg;
> + unsigned long flags;
> + unsigned int len;
> + u8 result;
> +
> + /* Protect list and virtio queue operations */
> + spin_lock_irqsave(&can_priv->tx_lock, flags);
> +
> + can_tx_msg = virtqueue_get_buf(vq, &len);
> + if (!can_tx_msg) {
> + spin_unlock_irqrestore(&can_priv->tx_lock, flags);
> + return 0; /* No more data */
> + }
> +
> + if (unlikely(len < sizeof(struct virtio_can_tx_in))) {
> + netdev_err(dev, "TX ACK: Device sent no result code\n");
> + result = VIRTIO_CAN_RESULT_NOT_OK; /* Keep things going */
> + } else {
> + result = can_tx_msg->tx_in.result;
> + }
> +
> + if (can_priv->can.state < CAN_STATE_BUS_OFF) {
> + /* Here also frames with result != VIRTIO_CAN_RESULT_OK are
> + * echoed. Intentional to bring a waiting process in an upper
> + * layer to an end.
> + * TODO: Any better means to indicate a problem here?
> + */
> + if (result != VIRTIO_CAN_RESULT_OK)
> + netdev_warn(dev, "TX ACK: Result = %u\n", result);
> +
> + stats->tx_bytes += can_get_echo_skb(dev, can_tx_msg->putidx,
> + NULL);
> + stats->tx_packets++;
> + } else {
> + netdev_dbg(dev, "TX ACK: Controller inactive, drop echo\n");
> + can_free_echo_skb(dev, can_tx_msg->putidx, NULL);
> + }
> +
> + list_del(&can_tx_msg->list);
> + virtio_can_free_tx_idx(can_priv, can_tx_msg->putidx);
> +
> + spin_unlock_irqrestore(&can_priv->tx_lock, flags);
> +
> + kfree(can_tx_msg);
> +
> + /* Flow control */
> + if (netif_queue_stopped(dev)) {
> + netdev_dbg(dev, "TX ACK: Wake up stopped queue\n");
> + netif_wake_queue(dev);
> + }
> +
> + return 1; /* Queue was not empty so there may be more data */
> +}
> +
> +/* Poll TX used queue for sent CAN messages
> + * See https://wiki.linuxfoundation.org/networking/napi function
> + * int (*poll)(struct napi_struct *napi, int budget);
> + */
> +static int virtio_can_tx_poll(struct napi_struct *napi, int quota)
> +{
> + struct net_device *dev = napi->dev;
> + struct virtio_can_priv *priv = netdev_priv(dev);
> + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_TX];
> + int work_done = 0;
> +
> + while (work_done < quota && virtio_can_read_tx_queue(vq) != 0)
> + work_done++;
> +
> + if (work_done < quota)
> + virtqueue_napi_complete(napi, vq, work_done);
> +
> + return work_done;
> +}
> +
> +static void virtio_can_tx_intr(struct virtqueue *vq)
> +{
> + struct virtio_can_priv *can_priv = vq->vdev->priv;
> +
> + virtqueue_disable_cb(vq);
> + napi_schedule(&can_priv->napi_tx);
> +}
> +
> +/* This function is the NAPI RX poll function and NAPI guarantees that this
> + * function is not invoked simultaneously on multiple processors.
> + * Read a RX message from the used queue and sends it to the upper layer.
> + * (See also m_can.c / m_can_read_fifo()).
> + */
> +static int virtio_can_read_rx_queue(struct virtqueue *vq)
> +{
> + struct virtio_can_priv *priv = vq->vdev->priv;
> + struct net_device *dev = priv->dev;
> + struct net_device_stats *stats = &dev->stats;
> + struct virtio_can_rx *can_rx;
> + struct canfd_frame *cf;
> + struct sk_buff *skb;
> + unsigned int transport_len;
> + unsigned int len;
> + const unsigned int header_size = offsetof(struct virtio_can_rx, sdu);
> + u16 msg_type;
> + u32 can_flags;
> + u32 can_id;
> +
> + can_rx = virtqueue_get_buf(vq, &transport_len);
> + if (!can_rx)
> + return 0; /* No more data */
> +
> + if (transport_len < header_size) {
> + netdev_warn(dev, "RX: Message too small\n");
> + goto putback;
> + }
> +
> + if (priv->can.state >= CAN_STATE_ERROR_PASSIVE) {
> + netdev_dbg(dev, "%s(): Controller not active\n", __func__);
> + goto putback;
> + }
> +
> + msg_type = le16_to_cpu(can_rx->msg_type);
> + if (msg_type != VIRTIO_CAN_RX) {
> + netdev_warn(dev, "RX: Got unknown msg_type %04x\n", msg_type);
> + goto putback;
> + }
> +
> + len = le16_to_cpu(can_rx->length);
> + can_flags = le32_to_cpu(can_rx->flags);
> + can_id = le32_to_cpu(can_rx->can_id);
> +
> + if (can_flags & ~CAN_KNOWN_FLAGS) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: Invalid flags 0x%x\n",
> + can_id, can_flags);
> + goto putback;
> + }
> +
> + if (can_flags & VIRTIO_CAN_FLAGS_EXTENDED) {
> + can_id &= CAN_EFF_MASK;
> + can_id |= CAN_EFF_FLAG;
> + } else {
> + can_id &= CAN_SFF_MASK;
> + }
> +
> + if (can_flags & VIRTIO_CAN_FLAGS_RTR) {
> + if (!virtio_has_feature(vq->vdev, VIRTIO_CAN_F_RTR_FRAMES)) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: RTR not negotiated\n",
> + can_id);
> + goto putback;
> + }
> + if (can_flags & VIRTIO_CAN_FLAGS_FD) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: RTR with FD not possible\n",
> + can_id);
> + goto putback;
> + }
> +
> + if (len > 0xF) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: RTR with DLC > 0xF\n",
> + can_id);
> + goto putback;
> + }
> +
> + if (len > 0x8)
> + len = 0x8;
> +
> + can_id |= CAN_RTR_FLAG;
> + }
> +
> + if (transport_len < header_size + len) {
> + netdev_warn(dev, "RX: Message too small for payload\n");
> + goto putback;
> + }
> +
> + if (can_flags & VIRTIO_CAN_FLAGS_FD) {
> + if (!virtio_has_feature(vq->vdev, VIRTIO_CAN_F_CAN_FD)) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: FD not negotiated\n",
> + can_id);
> + goto putback;
> + }
> +
> + if (len > CANFD_MAX_DLEN)
> + len = CANFD_MAX_DLEN;
> +
> + skb = alloc_canfd_skb(priv->dev, &cf);
> + } else {
> + if (!virtio_has_feature(vq->vdev, VIRTIO_CAN_F_CAN_CLASSIC)) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: CAN Id 0x%08x: classic not negotiated\n",
> + can_id);
> + goto putback;
> + }
> +
> + if (len > CAN_MAX_DLEN)
> + len = CAN_MAX_DLEN;
> +
> + skb = alloc_can_skb(priv->dev, (struct can_frame **)&cf);
> + }
> + if (!skb) {
> + stats->rx_dropped++;
> + netdev_warn(dev, "RX: No skb available\n");
> + goto putback;
> + }
> +
> + cf->can_id = can_id;
> + cf->len = len;
> + if (!(can_flags & VIRTIO_CAN_FLAGS_RTR)) {
> + /* RTR frames have a DLC but no payload */
> + memcpy(cf->data, can_rx->sdu, len);
> + }
> +
> + if (netif_receive_skb(skb) == NET_RX_SUCCESS) {
> + stats->rx_packets++;
> + if (!(can_flags & VIRTIO_CAN_FLAGS_RTR))
> + stats->rx_bytes += cf->len;
> + }
> +
> +putback:
> + /* Put processed RX buffer back into avail queue */
> + virtio_can_add_inbuf(vq, can_rx, sizeof(struct virtio_can_rx));
> +
> + return 1; /* Queue was not empty so there may be more data */
> +}
> +
> +/* See m_can_poll() / m_can_handle_state_errors() m_can_handle_state_change() */
> +static int virtio_can_handle_busoff(struct net_device *dev)
> +{
> + struct virtio_can_priv *priv = netdev_priv(dev);
> + struct can_frame *cf;
> + struct sk_buff *skb;
> +
> + if (!priv->busoff_pending)
> + return 0;
> +
> + if (priv->can.state < CAN_STATE_BUS_OFF) {
> + netdev_dbg(dev, "entered error bus off state\n");
> +
> + /* bus-off state */
> + priv->can.state = CAN_STATE_BUS_OFF;
> + priv->can.can_stats.bus_off++;
> + can_bus_off(dev);
> + }
> +
> + /* propagate the error condition to the CAN stack */
> + skb = alloc_can_err_skb(dev, &cf);
> + if (unlikely(!skb))
> + return 0;
> +
> + /* bus-off state */
> + cf->can_id |= CAN_ERR_BUSOFF;
> +
> + /* Ensure that the BusOff indication does not get lost */
> + if (netif_receive_skb(skb) == NET_RX_SUCCESS)
> + priv->busoff_pending = false;
> +
> + return 1;
> +}
> +
> +/* Poll RX used queue for received CAN messages
> + * See https://wiki.linuxfoundation.org/networking/napi function
> + * int (*poll)(struct napi_struct *napi, int budget);
> + * Important: "The networking subsystem promises that poll() will not be
> + * invoked simultaneously (for the same napi_struct) on multiple processors"
> + */
> +static int virtio_can_rx_poll(struct napi_struct *napi, int quota)
> +{
> + struct net_device *dev = napi->dev;
> + struct virtio_can_priv *priv = netdev_priv(dev);
> + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_RX];
> + int work_done = 0;
> +
> + work_done += virtio_can_handle_busoff(dev);
> +
> + while (work_done < quota && virtio_can_read_rx_queue(vq) != 0)
> + work_done++;
> +
> + if (work_done < quota)
> + virtqueue_napi_complete(napi, vq, work_done);
> +
> + return work_done;
> +}
> +
> +static void virtio_can_rx_intr(struct virtqueue *vq)
> +{
> + struct virtio_can_priv *can_priv = vq->vdev->priv;
> +
> + virtqueue_disable_cb(vq);
> + napi_schedule(&can_priv->napi);
> +}
> +
> +static void virtio_can_control_intr(struct virtqueue *vq)
> +{
> + struct virtio_can_priv *can_priv = vq->vdev->priv;
> +
> + complete(&can_priv->ctrl_done);
> +}
> +
> +static void virtio_can_config_changed(struct virtio_device *vdev)
> +{
> + struct virtio_can_priv *can_priv = vdev->priv;
> + u16 status;
> +
> + status = virtio_cread16(vdev, offsetof(struct virtio_can_config,
> + status));
> +
> + if (!(status & VIRTIO_CAN_S_CTRL_BUSOFF))
> + return;
> +
> + if (!can_priv->busoff_pending &&
> + can_priv->can.state < CAN_STATE_BUS_OFF) {
> + can_priv->busoff_pending = true;
> + napi_schedule(&can_priv->napi);
> + }
> +}
> +
> +static void virtio_can_populate_vqs(struct virtio_device *vdev)
> +
> +{
> + struct virtio_can_priv *priv = vdev->priv;
> + struct virtqueue *vq;
> + unsigned int idx;
> + int ret;
> +
> + /* Fill RX queue */
> + vq = priv->vqs[VIRTIO_CAN_QUEUE_RX];
> + for (idx = 0; idx < ARRAY_SIZE(priv->rpkt); idx++) {
> + ret = virtio_can_add_inbuf(vq, &priv->rpkt[idx],
> + sizeof(struct virtio_can_rx));
> + if (ret < 0) {
> + dev_dbg(&vdev->dev, "rpkt fill: ret=%d, idx=%u\n",
> + ret, idx);
> + break;
> + }
> + }
> + dev_dbg(&vdev->dev, "%u rpkt added\n", idx);
> +}
> +
> +static int virtio_can_find_vqs(struct virtio_can_priv *priv)
> +{
> + /* The order of RX and TX is exactly the opposite as in console and
> + * network. Does not play any role but is a bad trap.
> + */
> + static const char * const io_names[VIRTIO_CAN_QUEUE_COUNT] = {
> + "can-tx",
> + "can-rx",
> + "can-state-ctrl"
> + };
> +
> + priv->io_callbacks[VIRTIO_CAN_QUEUE_TX] = virtio_can_tx_intr;
> + priv->io_callbacks[VIRTIO_CAN_QUEUE_RX] = virtio_can_rx_intr;
> + priv->io_callbacks[VIRTIO_CAN_QUEUE_CONTROL] = virtio_can_control_intr;
> +
> + /* Find the queues. */
> + return virtio_find_vqs(priv->vdev, VIRTIO_CAN_QUEUE_COUNT, priv->vqs,
> + priv->io_callbacks, io_names, NULL);
> +}
> +
> +/* Function must not be called before virtio_can_find_vqs() has been run */
> +static void virtio_can_del_vq(struct virtio_device *vdev)
> +{
> + struct virtio_can_priv *priv = vdev->priv;
> + struct list_head *cursor, *next;
> + struct virtqueue *vq;
> +
> + /* Reset the device */
> + if (vdev->config->reset)
> + vdev->config->reset(vdev);
> +
> + /* From here we have dead silence from the device side so no locks
> + * are needed to protect against device side events.
> + */
> +
> + vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL];
> + while (virtqueue_detach_unused_buf(vq))
> + ; /* Do nothing, content allocated statically */
> +
> + vq = priv->vqs[VIRTIO_CAN_QUEUE_RX];
> + while (virtqueue_detach_unused_buf(vq))
> + ; /* Do nothing, content allocated statically */
> +
> + vq = priv->vqs[VIRTIO_CAN_QUEUE_TX];
> + while (virtqueue_detach_unused_buf(vq))
> + ; /* Do nothing, content to be de-allocated separately */
> +
> + /* Is keeping track of allocated elements by an own linked list
> + * really necessary or may this be optimized using only
> + * virtqueue_detach_unused_buf()?
> + */
> + list_for_each_safe(cursor, next, &priv->tx_list) {
> + struct virtio_can_tx *can_tx;
> +
> + can_tx = list_entry(cursor, struct virtio_can_tx, list);
> + list_del(cursor);
> + kfree(can_tx);
> + }
> +
> + if (vdev->config->del_vqs)
> + vdev->config->del_vqs(vdev);
> +}
> +
> +/* See virtio_net.c/virtnet_remove() and also m_can.c/m_can_plat_remove() */
> +static void virtio_can_remove(struct virtio_device *vdev)
> +{
> + struct virtio_can_priv *priv = vdev->priv;
> + struct net_device *dev = priv->dev;
> +
> + unregister_candev(dev);
> +
> + /* No calls of netif_napi_del() needed as free_candev() will do this */
> +
> + virtio_can_del_vq(vdev);
> +
> + virtio_can_free_candev(dev);
> +}
> +
> +static int virtio_can_validate(struct virtio_device *vdev)
> +{
> + /* CAN needs always access to the config space.
> + * Check that the driver can access the config space
> + */
> + if (!vdev->config->get) {
> + dev_err(&vdev->dev, "%s failure: config access disabled\n",
> + __func__);
> + return -EINVAL;
> + }
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> + dev_err(&vdev->dev,
> + "device does not comply with spec version 1.x\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int virtio_can_probe(struct virtio_device *vdev)
> +{
> + struct net_device *dev;
> + struct virtio_can_priv *priv;
> + int err;
> +
> + dev = alloc_candev(sizeof(struct virtio_can_priv),
> + VIRTIO_CAN_ECHO_SKB_MAX);
> + if (!dev)
> + return -ENOMEM;
> +
> + priv = netdev_priv(dev);
> +
> + ida_init(&priv->tx_putidx_ida);
> +
> + netif_napi_add(dev, &priv->napi, virtio_can_rx_poll);
> + netif_napi_add(dev, &priv->napi_tx, virtio_can_tx_poll);
> +
> + SET_NETDEV_DEV(dev, &vdev->dev);
> +
> + priv->dev = dev;
> + priv->vdev = vdev;
> + vdev->priv = priv;
> +
> + priv->can.do_set_mode = virtio_can_set_mode;
> + /* Set Virtio CAN supported operations */
> + priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING;
> + if (virtio_has_feature(vdev, VIRTIO_CAN_F_CAN_FD)) {
> + err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD);
> + if (err != 0)
> + goto on_failure;
> + }
> +
> + /* Initialize virtqueues */
> + err = virtio_can_find_vqs(priv);
> + if (err != 0)
> + goto on_failure;
> +
> + INIT_LIST_HEAD(&priv->tx_list);
> +
> + spin_lock_init(&priv->tx_lock);
> + mutex_init(&priv->ctrl_lock);
> +
> + init_completion(&priv->ctrl_done);
> +
> + virtio_can_populate_vqs(vdev);
> +
> + register_virtio_can_dev(dev);
> +
> + napi_enable(&priv->napi);
> + napi_enable(&priv->napi_tx);
> +
> + /* Request device going live */
> + virtio_device_ready(vdev); /* Optionally done by virtio_dev_probe() */
> +
> + return 0;
> +
> +on_failure:
> + virtio_can_free_candev(dev);
> + return err;
> +}
> +
> +/* Compare with m_can.c/m_can_suspend(), virtio_net.c/virtnet_freeze() and
> + * virtio_card.c/virtsnd_freeze()
> + */
> +static int __maybe_unused virtio_can_freeze(struct virtio_device *vdev)
> +{
> + struct virtio_can_priv *priv = vdev->priv;
> + struct net_device *ndev = priv->dev;
> +
> + napi_disable(&priv->napi);
> + napi_disable(&priv->napi_tx);
> +
> + if (netif_running(ndev)) {
> + netif_stop_queue(ndev);
> + netif_device_detach(ndev);
> + virtio_can_stop(ndev);
> + }
> +
> + priv->can.state = CAN_STATE_SLEEPING;
> +
> + virtio_can_del_vq(vdev);
> +
> + return 0;
> +}
> +
> +/* Compare with m_can.c/m_can_resume(), virtio_net.c/virtnet_restore() and
> + * virtio_card.c/virtsnd_restore()
> + */
> +static int __maybe_unused virtio_can_restore(struct virtio_device *vdev)
> +{
> + struct virtio_can_priv *priv = vdev->priv;
> + struct net_device *ndev = priv->dev;
> + int err;
> +
> + err = virtio_can_find_vqs(priv);
> + if (err != 0)
> + return err;
> + virtio_can_populate_vqs(vdev);
> +
> + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> + if (netif_running(ndev)) {
> + virtio_can_start(ndev);
> + netif_device_attach(ndev);
> + netif_start_queue(ndev);
> + }
> +
> + napi_enable(&priv->napi);
> + napi_enable(&priv->napi_tx);
> +
> + return 0;
> +}
> +
> +static struct virtio_device_id virtio_can_id_table[] = {
> + { VIRTIO_ID_CAN, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static unsigned int features[] = {
> + VIRTIO_CAN_F_CAN_CLASSIC,
> + VIRTIO_CAN_F_CAN_FD,
> + VIRTIO_CAN_F_LATE_TX_ACK,
> + VIRTIO_CAN_F_RTR_FRAMES,
> +};
> +
> +static struct virtio_driver virtio_can_driver = {
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .id_table = virtio_can_id_table,
> + .validate = virtio_can_validate,
> + .probe = virtio_can_probe,
> + .remove = virtio_can_remove,
> + .config_changed = virtio_can_config_changed,
> +#ifdef CONFIG_PM_SLEEP
> + .freeze = virtio_can_freeze,
> + .restore = virtio_can_restore,
> +#endif
> +};
> +
> +module_virtio_driver(virtio_can_driver);
> +MODULE_DEVICE_TABLE(virtio, virtio_can_id_table);
> +
> +MODULE_AUTHOR("OpenSynergy GmbH");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("CAN bus driver for Virtio CAN controller");
> diff --git a/include/uapi/linux/virtio_can.h b/include/uapi/linux/virtio_can.h
> new file mode 100644
> index 000000000000..f59a2ca6ebd1
> --- /dev/null
> +++ b/include/uapi/linux/virtio_can.h
> @@ -0,0 +1,71 @@
> +/* SPDX-License-Identifier: BSD-3-Clause */
> +/*
> + * Copyright (C) 2021-2023 OpenSynergy GmbH
> + */
> +#ifndef _LINUX_VIRTIO_VIRTIO_CAN_H
> +#define _LINUX_VIRTIO_VIRTIO_CAN_H
> +
> +#include <linux/types.h>
> +#include <linux/virtio_types.h>
> +#include <linux/virtio_ids.h>
> +#include <linux/virtio_config.h>
> +
> +/* Feature bit numbers */
> +#define VIRTIO_CAN_F_CAN_CLASSIC 0
> +#define VIRTIO_CAN_F_CAN_FD 1
> +#define VIRTIO_CAN_F_LATE_TX_ACK 2
> +#define VIRTIO_CAN_F_RTR_FRAMES 3
Why do we need both VIRTIO_CAN_F_RTR_FRAMES VIRTIO_CAN_FLAGS_RTR?
Is it to manage devices not able to sent remote frames? If so, we may
also need to add a CAN_CTRLMODE_RTR in linux/can/netlink.h?
> +
> +/* CAN Result Types */
> +#define VIRTIO_CAN_RESULT_OK 0
> +#define VIRTIO_CAN_RESULT_NOT_OK 1
Silly question, but what is the rationale of not using the error code
from errno.h?
I do see that some other virtio devices do the same:
https://elixir.bootlin.com/linux/v4.6/source/include/uapi/linux/virtio_net.h#L140
But I am genuinely curious to understand why virtio do not use more
standard error codes.
> +/* CAN flags to determine type of CAN Id */
> +#define VIRTIO_CAN_FLAGS_EXTENDED 0x8000
> +#define VIRTIO_CAN_FLAGS_FD 0x4000
> +#define VIRTIO_CAN_FLAGS_RTR 0x2000
> +
> +struct virtio_can_config {
> +#define VIRTIO_CAN_S_CTRL_BUSOFF (1u << 0) /* Controller BusOff */
> + /* CAN controller status */
> + __le16 status;
> +};
> +
> +/* TX queue message types */
> +struct virtio_can_tx_out {
> +#define VIRTIO_CAN_TX 0x0001
> + __le16 msg_type;
> + __le16 length; /* 0..8 CC, 0..64 CAN-FD, 0..2048 CAN-XL, 12 bits */
> + __le32 reserved; /* May be needed in part for CAN XL priority */
> + __le32 flags;
> + __le32 can_id;
> + __u8 sdu[64];
> +};
> +
> +struct virtio_can_tx_in {
> + __u8 result;
> +};
> +
> +/* RX queue message types */
> +struct virtio_can_rx {
> +#define VIRTIO_CAN_RX 0x0101
> + __le16 msg_type;
> + __le16 length; /* 0..8 CC, 0..64 CAN-FD, 0..2048 CAN-XL, 12 bits */
> + __le32 reserved; /* May be needed in part for CAN XL priority */
Can we use this field to report the classical CAN DLC greater than 8?
If also needed by CAN XL, the field can be turned into a union.
> + __le32 flags;
> + __le32 can_id;
> + __u8 sdu[64];
> +};
> +
> +/* Control queue message types */
> +struct virtio_can_control_out {
> +#define VIRTIO_CAN_SET_CTRL_MODE_START 0x0201
> +#define VIRTIO_CAN_SET_CTRL_MODE_STOP 0x0202
> + __le16 msg_type;
> +};
> +
> +struct virtio_can_control_in {
> + __u8 result;
> +};
> +
> +#endif /* #ifndef _LINUX_VIRTIO_VIRTIO_CAN_H */
> --
> 2.34.1
>
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