On Thu, Mar 05, 2026 at 09:17:47PM +0100, Matias Ezequiel Vara Larsen wrote:
> On Thu, Mar 05, 2026 at 07:36:32PM +0100, Harald Mommer wrote:
> >
> >
> > On 3/5/26 17:19, Matias Ezequiel Vara Larsen wrote:
> > > Add virtio CAN driver based on Virtio 1.4 specification (see
> > > https://github.com/oasis-tcs/virtio-spec/tree/virtio-1.4). The driver
> > > implements a complete CAN bus interface over Virtio transport,
> > > supporting both CAN Classic and CAN-FD Ids. In term of frames, it
> > > supports classic and CAN FD. RTR frames are only supported with classic
> > > CAN.
> > >
> > > Usage:
> > > - "ip link set up can0" - start controller
> > > - "ip link set down can0" - stop controller
> > > - "candump can0" - receive frames
> > > - "cansend can0 123#DEADBEEF" - send frames
> > >
> > > Signed-off-by: Harald Mommer <[email protected]>
> > > Co-developed-by: Harald Mommer <[email protected]>
> > > Signed-off-by: Mikhail Golubev-Ciuchea
> > > <[email protected]>
> > > Co-developed-by: Marc Kleine-Budde <[email protected]>
> > > Signed-off-by: Marc Kleine-Budde <[email protected]>
> > > Cc: Damir Shaikhutdinov <[email protected]>
> > > Reviewed-by: Francesco Valla <[email protected]>
> > > Tested-by: Francesco Valla <[email protected]>
> > > Signed-off-by: Matias Ezequiel Vara Larsen <[email protected]>
> > > ---
> > > V12:
> > > - check return value in virtio_can_start()
> > > - use devm_krealloc() in virtio_can_restore() to re-allocate rpkt
> > > - remove access to cf->len and replace it with len
> > > - use __counted_by_le()
> > > - free tx buffers during virtio_can_del_vq()
> > > - add reinit_completion() for ctrl msgs
> > >
> > > V11:
> > > * Set CAN_VIRTIO_CAN config before CAN_XILINXCAN
> > > * Use GFP_ATOMIC in virtio_can_alloc_tx_idx()
> > > * Use open_candev() and set bittiming.bitrate to CAN_BITRATE_UNKNOWN and
> > > data_bittiming.bitrate to CAN_BITRATE_UNKNOWN
> > > * Fix leak of skb by adding kfree_skb(skb)
> > > * Fix out-of-bounds in virtio_can_populate_rx_vq()
> > > * Initialize `ret`
> > > * Use virtio_reset_device()
> > > * Add napi_disable() in virtio_can_remove()
> > > * Propagate error in virtio_can_start() and virtio_can_stop()
> > >
> > > V10:
> > > * Follow Reverse Christmas Tree convention
> > >
> > > V9:
> > > * Remove unnecessary comments
> > > * Update maintainer list
> > >
> > > V8:
> > > * Address nits
> > >
> > > V7:
> > > * Address nits
> > > * Remove unnecessary comments
> > > * Remove io_callbacks[]
> > > * Use guard() syntax
> > > * Remove kicking for each inbuf
> > > * replace sdu_len with rpkt_len
> > > * Use devm_kzalloc()
> > > * Use scoped_guard() to protect virtqueue_add_sgs() and virtqueue_kicks()
> > > for
> > > tx queue
> > > * Tested with vhost-device-can
> > > (see
> > > https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-can) and
> > > Qemu (942b0d3) with [1]. A reviewer observed that the device stops to
> > > work
> > > after flooding from host. This issue is still present.
> > >
> > > [1]
> > > https://lore.kernel.org/qemu-devel/[email protected]/
> > >
> > > V6:
> > > * Address nits
> > > * Check for error during register_virtio_can()
> > > * Remove virtio_device_ready()
> > > * Allocate virtio_can_rx rpkt[] at probe
> > > * Define virtio_can_control struct
> > > * Return VIRTIO_CAN_RESULT_NOT_OK after unlocking
> > > * Define sdu[] as a flex array for both tx and rx. For rx, use
> > > VIRTIO_CAN_F_CAN_FD to figure out the max len for sdu
> > > * Fix statistics in virtio_can_read_tx_queue() and
> > > how we indicate error to the user when getting
> > > VIRTIO_CAN_RESULT_NOT_OK
> > > * Fix syntax of virtio_find_vqs()
> > > * Drop tx_list
> > > * Fix values of VIRTIO_CAN_F_LATE_TX_ACK and VIRTIO_CAN_F_RTR_FRAMES
> > > * Tested with vhost-device-can
> > > (see
> > > https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-can)
> > > and qemu (see
> > > https://github.com/virtualopensystems/qemu/tree/vhu-can-rfc)
> > >
> > > V5:
> > > * Re-base on top of linux-next (next-20240103)
> > > * Tested with
> > > https://github.com/OpenSynergy/qemu/tree/virtio-can-spec-rfc-v3
> > >
> > > RFC V4:
> > > * Apply reverse Christmas tree style
> > > * Add member *classic_dlc to RX and TX CAN frames
> > > * Fix race causing a NETDEV_TX_BUSY return
> > > ---
> > > MAINTAINERS | 9 +
> > > drivers/net/can/Kconfig | 12 +
> > > drivers/net/can/Makefile | 1 +
> > > drivers/net/can/virtio_can.c | 986 ++++++++++++++++++++++++++++++++
> > > include/uapi/linux/virtio_can.h | 78 +++
> > > 5 files changed, 1086 insertions(+)
> > > 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 80cd3498c293..f295a904c93e 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -27068,6 +27068,15 @@ F: drivers/scsi/virtio_scsi.c
> > > F: include/uapi/linux/virtio_blk.h
> > > F: include/uapi/linux/virtio_scsi.h
> > >
> > > +VIRTIO CAN DRIVER
> > > +M: "Harald Mommer" <[email protected]>
> > > +M: "Matias Ezequiel Vara Larsen" <[email protected]>
> > > +L: [email protected]
> > > +L: [email protected]
> > > +S: Maintained
> > > +F: drivers/net/can/virtio_can.c
> > > +F: include/uapi/linux/virtio_can.h
> > > +
> > > VIRTIO CONSOLE DRIVER
> > > M: Amit Shah <[email protected]>
> > > L: [email protected]
> > > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> > > index d43d56694667..f33ae46d9766 100644
> > > --- a/drivers/net/can/Kconfig
> > > +++ b/drivers/net/can/Kconfig
> > > @@ -209,6 +209,18 @@ config CAN_TI_HECC
> > > Driver for TI HECC (High End CAN Controller) module found on many
> > > TI devices. The device specifications are available from www.ti.com
> > >
> > > +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.
> > > +
> > > + To compile this driver as a module, choose M here: the
> > > + module will be called virtio-can.
> > > +
> > > + If unsure, say N.
> > > +
> > > config CAN_XILINXCAN
> > > tristate "Xilinx CAN"
> > > depends on ARCH_ZYNQ || ARM64 || MICROBLAZE || COMPILE_TEST
> > > diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> > > index 56138d8ddfd2..2ddea733ed5d 100644
> > > --- a/drivers/net/can/Makefile
> > > +++ b/drivers/net/can/Makefile
> > > @@ -32,6 +32,7 @@ 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..f27e603524c9
> > > --- /dev/null
> > > +++ b/drivers/net/can/virtio_can.c
> > > @@ -0,0 +1,986 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * CAN bus driver for the Virtio CAN controller
> > > + *
> > > + * Copyright (C) 2021-2023 OpenSynergy GmbH
> > > + * Copyright Red Hat, Inc. 2025
> > > + */
> > > +
> > > +#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
> > > +#define VIRTIO_CAN_QUEUE_RX 1
> > > +#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 {
> > > + unsigned int putidx;
> > > + struct virtio_can_tx_in tx_in;
> > > + /* Keep virtio_can_tx_out at the end of the structure due to flex array
> > > */
> > > + struct virtio_can_tx_out tx_out;
> > > +};
> > > +
> > > +struct virtio_can_control {
> > > + struct virtio_can_control_out cpkt_out;
> > > + struct virtio_can_control_in cpkt_in;
> > > +};
> > > +
> > > +/* 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];
> > > + /* Lock for TX operations */
> > > + spinlock_t tx_lock;
> > > + /* Control queue lock */
> > > + struct mutex ctrl_lock;
> > > + /* Wait for control queue processing without polling */
> > > + struct completion ctrl_done;
> > > + /* Array of receive queue messages */
> > > + struct virtio_can_rx *rpkt;
> > > + struct virtio_can_control can_ctr_msg;
> > > + /* Data to get and maintain the putidx for local TX echo */
> > > + struct ida tx_putidx_ida;
> > > + /* In flight TX messages */
> > > + atomic_t tx_inflight;
> > > + /* Packet length */
> > > + int rpkt_len;
> > > + /* BusOff pending. Reset after successful indication to upper layer */
> > > + bool busoff_pending;
> > > +};
> > > +
> > > +static void virtqueue_napi_schedule(struct napi_struct *napi,
> > > + struct virtqueue *vq)
> > > +{
> > > + if (napi_schedule_prep(napi)) {
> > > + virtqueue_disable_cb(vq);
> > > + __napi_schedule(napi);
> > > + }
> > > +}
> > > +
> > > +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_max(&priv->tx_putidx_ida,
> > > + priv->can.echo_skb_max - 1, GFP_ATOMIC);
> > > + if (tx_idx >= 0)
> > > + atomic_inc(&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_dec(&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);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +/* Send a control message with message type either
> > > + *
> > > + * - VIRTIO_CAN_SET_CTRL_MODE_START or
> > > + * - VIRTIO_CAN_SET_CTRL_MODE_STOP.
> > > + *
> > > + */
> > > +static u8 virtio_can_send_ctrl_msg(struct net_device *ndev, u16 msg_type)
> > > +{
> > > + struct scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in };
> > > + struct virtio_can_priv *priv = netdev_priv(ndev);
> > > + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL];
> > > + struct device *dev = &priv->vdev->dev;
> > > + unsigned int len;
> > > + int err;
> > > +
> > > + guard(mutex)(&priv->ctrl_lock);
> > > +
> > > + priv->can_ctr_msg.cpkt_out.msg_type = cpu_to_le16(msg_type);
> > > + sg_init_one(&sg_out, &priv->can_ctr_msg.cpkt_out,
> > > + sizeof(priv->can_ctr_msg.cpkt_out));
> > > + sg_init_one(&sg_in, &priv->can_ctr_msg.cpkt_in,
> > > sizeof(priv->can_ctr_msg.cpkt_in));
> > > +
> > > + reinit_completion(&priv->ctrl_done);
> > > +
> > > + err = virtqueue_add_sgs(vq, sgs, 1u, 1u, priv, GFP_ATOMIC);
> > > + if (err != 0) {
> > > + dev_err(dev, "%s(): virtqueue_add_sgs() failed\n", __func__);
> > > + return VIRTIO_CAN_RESULT_NOT_OK;
> > > + }
> > > +
> > > + if (!virtqueue_kick(vq)) {
> > > + dev_err(dev, "%s(): Kick failed\n", __func__);
> > > + return VIRTIO_CAN_RESULT_NOT_OK;
> > > + }
> > > +
> > > + while (!virtqueue_get_buf(vq, &len) && !virtqueue_is_broken(vq))
> > > + wait_for_completion(&priv->ctrl_done);
> > > +
> > > + return priv->can_ctr_msg.cpkt_in.result;
> > > +}
> > > +
> > > +static int 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) {
> > > + netdev_err(ndev, "CAN controller start failed\n");
> > > + return -EIO;
> > > + }
> > > +
> > > + priv->busoff_pending = false;
> > > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int virtio_can_set_mode(struct net_device *dev, enum can_mode
> > > mode)
> > > +{
> > > + int err;
> > > +
> > > + switch (mode) {
> > > + case CAN_MODE_START:
> > > + err = virtio_can_start(dev);
> > > + if (err)
> > > + return err;
> > > + netif_wake_queue(dev);
> > > + break;
> > > + default:
> > > + return -EOPNOTSUPP;
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int virtio_can_open(struct net_device *ndev)
> > > +{
> > > + int err;
> > > +
> > > + err = open_candev(ndev);
> > > + if (err)
> > > + return err;
> > > +
> > > + err = virtio_can_start(ndev);
> > > + if (err) {
> > > + close_candev(ndev);
> > > + return err;
> > > + }
> > > +
> > > + netif_start_queue(ndev);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int 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");
> > > + return -EIO;
> > > + }
> > > +
> > > + 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);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int virtio_can_close(struct net_device *dev)
> > > +{
> > > + int err;
> > > +
> > > + 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
> > > + */
> > > + err = virtio_can_stop(dev);
> > > + close_candev(dev);
> > > +
> > > + return err;
> > > +}
> > > +
> > > +static netdev_tx_t virtio_can_start_xmit(struct sk_buff *skb,
> > > + struct net_device *dev)
> > > +{
> > > + struct scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in };
> > > + const unsigned int hdr_size = sizeof(struct virtio_can_tx_out);
> > > + struct canfd_frame *cf = (struct canfd_frame *)skb->data;
> > > + struct virtio_can_priv *priv = netdev_priv(dev);
> > > + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_TX];
> > > + netdev_tx_t xmit_ret = NETDEV_TX_OK;
> > > + struct virtio_can_tx *can_tx_msg;
> > > + u32 can_flags;
> > > + int putidx;
> > > + int err;
> > > +
> > > + 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) + cf->len, GFP_ATOMIC);
> > > + if (!can_tx_msg) {
> > > + kfree_skb(skb);
> > > + dev->stats.tx_dropped++;
> > > + 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);
> > > +
> > > + sg_init_one(&sg_out, &can_tx_msg->tx_out, hdr_size + cf->len);
> > > + sg_init_one(&sg_in, &can_tx_msg->tx_in, sizeof(can_tx_msg->tx_in));
> > > +
> > > + putidx = virtio_can_alloc_tx_idx(priv);
> > > +
> > > + if (unlikely(putidx < 0)) {
> > > + /* -ENOMEM or -ENOSPC here. -ENOSPC should not be possible as
> > > + * tx_inflight >= can.echo_skb_max is checked in flow control
> > > + */
> > > + WARN_ON_ONCE(putidx == -ENOSPC);
> > > + kfree(can_tx_msg);
> > > + kfree_skb(skb);
> > > + dev->stats.tx_dropped++;
> > > + goto kick; /* No way to return NET_XMIT_DROP here */
> > > + }
> > > +
> > > + can_tx_msg->putidx = (unsigned int)putidx;
> > > +
> > > + /* 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 */
> > > + scoped_guard(spinlock_irqsave, &priv->tx_lock)
> > > + err = virtqueue_add_sgs(vq, sgs, 1u, 1u, can_tx_msg,
> > > GFP_ATOMIC);
> > > +
> > > + if (unlikely(err)) {
> > > + can_free_echo_skb(dev, can_tx_msg->putidx, NULL);
> > > + virtio_can_free_tx_idx(priv, can_tx_msg->putidx);
> > > + netif_stop_queue(dev);
> > > + kfree(can_tx_msg);
> > > + /* Expected never to be seen */
> > > + netdev_warn(dev, "TX: Stop queue, err = %d\n", err);
> > > + xmit_ret = NETDEV_TX_BUSY;
> > > + goto kick;
> > > + }
> > > +
> > > + /* Normal flow control: stop queue when no transmission slots left */
> > > + if (atomic_read(&priv->tx_inflight) >= priv->can.echo_skb_max ||
> > > + vq->num_free == 0 || (vq->num_free < ARRAY_SIZE(sgs) &&
> > > + !virtio_has_feature(vq->vdev, VIRTIO_RING_F_INDIRECT_DESC))) {
> > > + netif_stop_queue(dev);
> > > + netdev_dbg(dev, "TX: Normal stop queue\n");
> > > + }
> > > +
> > > +kick:
> > > + if (netif_queue_stopped(dev) || !netdev_xmit_more()) {
> > > + scoped_guard(spinlock_irqsave, &priv->tx_lock) {
> > > + 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,
> > > +};
> > > +
> > > +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);
> > > +}
> > > +
> > > +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 virtio_can_tx *can_tx_msg;
> > > + struct net_device_stats *stats;
> > > + unsigned int len;
> > > + u8 result;
> > > +
> > > + stats = &dev->stats;
> > > +
> > > + scoped_guard(spinlock_irqsave, &can_priv->tx_lock)
> > > + can_tx_msg = virtqueue_get_buf(vq, &len);
> > > +
> > > + if (!can_tx_msg)
> > > + return 0;
> > > +
> > > + 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) {
> > > + if (result != VIRTIO_CAN_RESULT_OK) {
> > > + struct can_frame *skb_cf;
> > > + struct sk_buff *skb = alloc_can_err_skb(dev, &skb_cf);
> > > +
> > > + if (skb) {
> > > + skb_cf->can_id |= CAN_ERR_CRTL;
> > > + skb_cf->data[1] |= CAN_ERR_CRTL_UNSPEC;
> > > + netif_rx(skb);
> > > + }
> > > + netdev_warn(dev, "TX ACK: Result = %u\n", result);
> > > + can_free_echo_skb(dev, can_tx_msg->putidx, NULL);
> > > + stats->tx_dropped++;
> > > + } else {
> > > + 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);
> > > + stats->tx_dropped++;
> > > + }
> > > +
> > > + virtio_can_free_tx_idx(can_priv, can_tx_msg->putidx);
> > > +
> > > + /* Flow control */
> > > + if (netif_queue_stopped(dev)) {
> > > + netdev_dbg(dev, "TX ACK: Wake up stopped queue\n");
> > > + netif_wake_queue(dev);
> > > + }
> > > +
> > > + kfree(can_tx_msg);
> > > +
> > > + return 1; /* Queue was not empty so there may be more data */
> > > +}
> > > +
> > > +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.
> > > + */
> > > +static int virtio_can_read_rx_queue(struct virtqueue *vq)
> > > +{
> > > + const unsigned int header_size = sizeof(struct virtio_can_rx);
> > > + struct virtio_can_priv *priv = vq->vdev->priv;
> > > + struct net_device *dev = priv->dev;
> > > + struct net_device_stats *stats;
> > > + struct virtio_can_rx *can_rx;
> > > + unsigned int transport_len;
> > > + struct canfd_frame *cf;
> > > + struct sk_buff *skb;
> > > + unsigned int len;
> > > + u32 can_flags;
> > > + u16 msg_type;
> > > + u32 can_id;
> > > + int ret;
> > > +
> > > + stats = &dev->stats;
> > > +
> > > + 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 += len;
> > > + }
> > > +
> > > +putback:
> > > + /* Put processed RX buffer back into avail queue */
> > > + ret = virtio_can_add_inbuf(vq, can_rx,
> > > + priv->rpkt_len);
> > > + if (!ret)
> > > + virtqueue_kick(vq);
> > > + return 1; /* Queue was not empty so there may be more data */
> > > +}
> > > +
> > > +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;
> > > +}
> > > +
> > > +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_rx_vq(struct virtio_device *vdev)
> > > +{
> > > + struct virtio_can_priv *priv = vdev->priv;
> > > + struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_RX];
> > > + unsigned int buf_size = priv->rpkt_len;
> > > + int num_elements = vq->num_free;
> > > + u8 *buf = (u8 *)priv->rpkt;
> > > + unsigned int idx;
> > > + int ret = 0;
> > > +
> > > + for (idx = 0; idx < num_elements; idx++) {
> > > + ret = virtio_can_add_inbuf(vq, buf, buf_size);
> > > + if (ret < 0) {
> > > + dev_dbg(&vdev->dev, "rpkt fill: ret=%d, idx=%u,
> > > size=%u\n",
> > > + ret, idx, buf_size);
> > > + break;
> > > + }
> > > + buf += buf_size;
> > > + }
> > > +
> > > + if (!ret)
> > > + virtqueue_kick(vq);
> > > +
> > > + dev_dbg(&vdev->dev, "%u rpkt added\n", idx);
> > > +}
> > > +
> > > +static int virtio_can_find_vqs(struct virtio_can_priv *priv)
> > > +{
> > > + struct virtqueue_info vqs_info[] = {
> > > + { "can-tx", virtio_can_tx_intr },
> > > + { "can-rx", virtio_can_rx_intr },
> > > + { "can-state-ctrl", virtio_can_control_intr },
> > > + };
> > > +
> > > + /* Find the queues. */
> > > + return virtio_find_vqs(priv->vdev, VIRTIO_CAN_QUEUE_COUNT, priv->vqs,
> > > + vqs_info, 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 virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_TX];
> > > + struct virtio_can_tx *can_tx_msg;
> > > + int q;
> > > +
> > > + /* Reset the device */
> > > + virtio_reset_device(vdev);
> > > +
> > > + /* From here we have dead silence from the device side so no locks
> > > + * are needed to protect against device side events.
> > > + */
> > > +
> > > + /* Free pending TX buffers which were allocated in
> > > virtio_can_start_xmit() */
> > > + while ((can_tx_msg = virtqueue_detach_unused_buf(vq))) {
> > > + can_free_echo_skb(priv->dev, can_tx_msg->putidx, NULL);
> > > + virtio_can_free_tx_idx(priv, can_tx_msg->putidx);
> > > + kfree(can_tx_msg);
> > > + }
> > > +
> > > + /* RX and control queue buffers are managed elsewhere, just detach */
> > > + for (q = VIRTIO_CAN_QUEUE_RX; q < VIRTIO_CAN_QUEUE_COUNT; q++)
> > > + while (virtqueue_detach_unused_buf(priv->vqs[q]))
> > > + ;
> > > +
> > > + if (vdev->config->del_vqs)
> > > + vdev->config->del_vqs(vdev);
> > > +}
> > > +
> > > +static void virtio_can_remove(struct virtio_device *vdev)
> > > +{
> > > + struct virtio_can_priv *priv = vdev->priv;
> > > + struct net_device *dev = priv->dev;
> > > +
> > > + napi_disable(&priv->napi);
> > > + napi_disable(&priv->napi_tx);
> > > +
> > > + unregister_candev(dev);
> > > +
> > > + 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 virtio_can_priv *priv;
> > > + struct net_device *dev;
> > > + size_t size;
> > > + 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;
> > > + priv->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN;
> > > + /* Set Virtio CAN supported operations */
> > > + priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING;
> > > + if (virtio_has_feature(vdev, VIRTIO_CAN_F_CAN_FD)) {
> > > + priv->can.fd.data_bittiming.bitrate = CAN_BITRATE_UNKNOWN;
> > > + 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;
> > > +
> > > + spin_lock_init(&priv->tx_lock);
> > > + mutex_init(&priv->ctrl_lock);
> > > +
> > > + init_completion(&priv->ctrl_done);
> > > +
> > > + priv->rpkt_len = sizeof(struct virtio_can_rx);
> > > +
> > > + if (virtio_has_feature(vdev, VIRTIO_CAN_F_CAN_FD))
> > > + priv->rpkt_len += CANFD_MAX_DLEN;
> > > + else
> > > + priv->rpkt_len += CAN_MAX_DLEN;
> > > +
> > > + size = priv->rpkt_len * priv->vqs[VIRTIO_CAN_QUEUE_RX]->num_free;
> > > + priv->rpkt = devm_kzalloc(&vdev->dev, size, GFP_KERNEL);
> > > + if (!priv->rpkt) {
> > > + virtio_can_del_vq(vdev);
> > > + err = -ENOMEM;
> > > + goto on_failure;
> > > + }
> > > + virtio_can_populate_rx_vq(vdev);
> > > +
> > > + err = register_virtio_can_dev(dev);
> > > + if (err) {
> > > + virtio_can_del_vq(vdev);
> > > + goto on_failure;
> > > + }
> > > +
> > > + napi_enable(&priv->napi);
> > > + napi_enable(&priv->napi_tx);
> > > +
> > > + return 0;
> > > +
> > > +on_failure:
> > > + virtio_can_free_candev(dev);
> > > + return err;
> > > +}
> > > +
> > > +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)) {
> > > + int err;
> > > +
> > > + netif_stop_queue(ndev);
> > > + netif_device_detach(ndev);
> > > + err = virtio_can_stop(ndev);
> > > + if (err)
> > > + return err;
> > > + }
> > > +
> > > + priv->can.state = CAN_STATE_SLEEPING;
> > > +
> > > + virtio_can_del_vq(vdev);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int __maybe_unused virtio_can_restore(struct virtio_device *vdev)
> > > +{
> > > + struct virtio_can_priv *priv = vdev->priv;
> > > + struct net_device *ndev = priv->dev;
> > > + size_t size;
> > > + int err;
> > > +
> > > + err = virtio_can_find_vqs(priv);
> > > + if (err != 0)
> > > + return err;
> > > +
> > > + size = priv->rpkt_len * priv->vqs[VIRTIO_CAN_QUEUE_RX]->num_free;
> > > + priv->rpkt = devm_krealloc(&vdev->dev, priv->rpkt, size, GFP_KERNEL |
> > > __GFP_ZERO);
> > > + if (!priv->rpkt) {
> > > + virtio_can_del_vq(vdev);
> > > + return -ENOMEM;
> > > + }
> > > + virtio_can_populate_rx_vq(vdev);
> > > +
> > > + priv->can.state = CAN_STATE_ERROR_ACTIVE;
> >
> > Is it ok that
> > priv->can.state remains CAN_STATE_ERROR_ACTIVE when there is an error
> > below?
> > May be that the state change comes too early now as there is now a new
> > possible error case below which previously was not there.
> >
> > > +
> > > + if (netif_running(ndev)) {
> > > + err = virtio_can_start(ndev);
> > > + if (err)
> > > + return err;
> >
> > Jumping between virtio_can_freeze() and virtio_can_restore() it may be that
> > the queues also should be rolled back in the error case by
> > virtio_can_del_vq() so that we have the same internal state as we had
> > before virtio_can_restore() was called.
> >
>
> Good catch. I think I need to add virtio_can_del_vq(vdev) when
> virtio_can_start() fails.
>
>
And also letting virtio_can_start() to set CAN_STATE_ERROR_ACTIVE.
Matias
>
> > Yesterday looking into the AI's review comments I thought first returning
> > an error was enough to handle this, than I was not sure any more that this
> > was enough but that it may be necessary to roll back some things done
> > before the error occurred. Could be that I'm wrong here getting headache
> > for nothing but in the moment I believe some rollback is missing.
> >
> > > + 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..08d7e3e78776
> > > --- /dev/null
> > > +++ b/include/uapi/linux/virtio_can.h
> > > @@ -0,0 +1,78 @@
> > > +/* SPDX-License-Identifier: BSD-3-Clause */
> > > +/*
> > > + * Copyright (C) 2021-2023 OpenSynergy GmbH
> > > + * Copyright Red Hat, Inc. 2025
> > > + */
> > > +#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_RTR_FRAMES 2
> > > +#define VIRTIO_CAN_F_LATE_TX_ACK 3
> > > +
> > > +/* CAN Result Types */
> > > +#define VIRTIO_CAN_RESULT_OK 0
> > > +#define VIRTIO_CAN_RESULT_NOT_OK 1
> > > +
> > > +/* 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
> > > +
> > > +#define VIRTIO_CAN_MAX_DLEN 64 // this is like CANFD_MAX_DLEN
> > > +
> > > +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 */
> > > + __u8 reserved_classic_dlc; /* If CAN classic length = 8 then DLC can be
> > > 8..15 */
> > > + __u8 padding;
> > > + __le16 reserved_xl_priority; /* May be needed for CAN XL priority */
> > > + __le32 flags;
> > > + __le32 can_id;
> > > + __u8 sdu[] __counted_by_le(length);
> > > +};
> > > +
> > > +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 */
> > > + __u8 reserved_classic_dlc; /* If CAN classic length = 8 then DLC can be
> > > 8..15 */
> > > + __u8 padding;
> > > + __le16 reserved_xl_priority; /* May be needed for CAN XL priority */
> > > + __le32 flags;
> > > + __le32 can_id;
> > > + __u8 sdu[] __counted_by_le(length);
> > > +};
> > > +
> > > +/* 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 */
> >
