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Tsirkin" , Jason Wang , Xuan Zhuo , linux-can@vger.kernel.org, virtualization@lists.linux.dev, Wolfgang Grandegger , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Stefano Garzarella , mvaralar@redhat.com, francesco@valla.it, mst@redhat.com Subject: [PATCH v10] can: virtio: Add virtio CAN driver Message-ID: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: o9rp9oAabkGmROoUNFQq4iz5VtqOfoMptAEg2ANtQMQ_1771323889 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 Co-developed-by: Harald Mommer Signed-off-by: Mikhail Golubev-Ciuchea Co-developed-by: Marc Kleine-Budde Signed-off-by: Marc Kleine-Budde Cc: Damir Shaikhutdinov Reviewed-by: Francesco Valla Tested-by: Francesco Valla Signed-off-by: Matias Ezequiel Vara Larsen --- 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/20251031155617.1223248-1-mvaralar@redhat.com/ 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 | 934 ++++++++++++++++++++++++++++++++ include/uapi/linux/virtio_can.h | 78 +++ 5 files changed, 1034 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" +M: "Matias Ezequiel Vara Larsen" +L: virtualization@lists.linux.dev +L: linux-can@vger.kernel.org +S: Maintained +F: drivers/net/can/virtio_can.c +F: include/uapi/linux/virtio_can.h + VIRTIO CONSOLE DRIVER M: Amit Shah L: virtualization@lists.linux.dev diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig index d43d56694667..7b5806f11853 100644 --- a/drivers/net/can/Kconfig +++ b/drivers/net/can/Kconfig @@ -217,6 +217,18 @@ 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. + + 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 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..8d60336b3ebe --- /dev/null +++ b/drivers/net/can/virtio_can.c @@ -0,0 +1,934 @@ +// 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* 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_KERNEL); + 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)); + + 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 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) + 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); +} + +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; +} + +static int virtio_can_open(struct net_device *ndev) +{ + virtio_can_start(ndev); + + netif_start_queue(ndev); + + 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 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) { + 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); + 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 += cf->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]; + struct virtio_can_rx *buf = priv->rpkt; + unsigned int buf_size = priv->rpkt_len; + int num_elements = vq->num_free; + unsigned int idx; + int ret; + + 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; + int q; + + /* 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. + */ + + for (q = 0; 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; + + 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; + 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; + + 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; + + priv->rpkt = devm_kzalloc(&vdev->dev, priv->rpkt_len * + priv->vqs[VIRTIO_CAN_QUEUE_RX]->num_free, + 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)) { + 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; +} + +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_rx_vq(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..ade068188d22 --- /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 +#include +#include +#include + +/* 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(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(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 */ -- 2.42.0