From: Harald Mommer <harald.mommer@xxxxxxxxxxxxxxx> - 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@xxxxxxxxxxxxxxx> Signed-off-by: Mikhail Golubev-Ciuchea <Mikhail.Golubev-Ciuchea@xxxxxxxxxxxxxxx> Co-developed-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Cc: Damir Shaikhutdinov <Damir.Shaikhutdinov@xxxxxxxxxxxxxxx> --- 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 * Fix TX queue going stuck on -ENOMEM * Update stats.tx_dropped on kzalloc() failure * Replace "(err != 0)" with "(unlikely(err))" * Use "ARRAY_SIZE(sgs)" * Refactor SGs in virtio_can_send_ctrl_msg() * Tested with https://github.com/OpenSynergy/qemu/tree/virtio-can-spec-rfc-v3 RFC V3: * Incorporate patch "[PATCH] can: virtio-can: cleanups" from https://lore.kernel.org/all/20230424-footwear-daily-9339bd0ec428-mkl@xxxxxxxxxxxxxx/ * 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 RFC 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 | 1 + drivers/net/can/virtio_can.c | 1008 +++++++++++++++++++++++++++++++ include/uapi/linux/virtio_can.h | 75 +++ 5 files changed, 1103 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 cef9597b90ac..d3892370db2b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -23214,6 +23214,13 @@ 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" <harald.mommer@xxxxxxxxxxxxxxx> +L: linux-can@xxxxxxxxxxxxxxx +S: Maintained +F: drivers/net/can/virtio_can.c +F: include/uapi/linux/virtio_can.h + VIRTIO CONSOLE DRIVER M: Amit Shah <amit@xxxxxxxxxx> L: virtualization@xxxxxxxxxxxxxxx diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig index eb410714afc2..f966bab19ed8 100644 --- a/drivers/net/can/Kconfig +++ b/drivers/net/can/Kconfig @@ -215,6 +215,18 @@ 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 ff8f76295d13..4488e591736e 100644 --- a/drivers/net/can/Makefile +++ b/drivers/net/can/Makefile @@ -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..924a7c19e438 --- /dev/null +++ b/drivers/net/can/virtio_can.c @@ -0,0 +1,1008 @@ +// 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; +}; + +/* 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 scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in }; + struct virtio_can_priv *priv = netdev_priv(ndev); + struct device *dev = &priv->vdev->dev; + struct virtqueue *vq; + unsigned int len; + int err; + + vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL]; + + /* 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, &priv->cpkt_out, sizeof(priv->cpkt_out)); + sg_init_one(&sg_in, &priv->cpkt_in, sizeof(priv->cpkt_in)); + + err = virtqueue_add_sgs(vq, sgs, 1u, 1u, priv, GFP_ATOMIC); + if (err != 0) { + /* 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) +{ + const unsigned int hdr_size = offsetof(struct virtio_can_tx_out, sdu); + struct scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in }; + struct canfd_frame *cf = (struct canfd_frame *)skb->data; + struct virtio_can_priv *priv = netdev_priv(dev); + netdev_tx_t xmit_ret = NETDEV_TX_OK; + struct virtio_can_tx *can_tx_msg; + struct virtqueue *vq; + unsigned long flags; + u32 can_flags; + int putidx; + int err; + + vq = priv->vqs[VIRTIO_CAN_QUEUE_TX]; + + 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) { + 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); + + /* Prepare sending of virtio message */ + 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; + + /* 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 (unlikely(err)) { /* checking vq->num_free in flow control */ + 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); + /* 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"); + } + + 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 virtio_can_tx *can_tx_msg; + struct net_device_stats *stats; + unsigned long flags; + unsigned int len; + u8 result; + + stats = &dev->stats; + + /* 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); + + /* Flow control */ + if (netif_queue_stopped(dev)) { + netdev_dbg(dev, "TX ACK: Wake up stopped queue\n"); + netif_wake_queue(dev); + } + + spin_unlock_irqrestore(&can_priv->tx_lock, flags); + + kfree(can_tx_msg); + + 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; + struct virtqueue *vq; + int work_done = 0; + + priv = netdev_priv(dev); + vq = priv->vqs[VIRTIO_CAN_QUEUE_TX]; + + 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) +{ + const unsigned int header_size = offsetof(struct virtio_can_rx, sdu); + 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; + + 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 */ + 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; + struct virtqueue *vq; + int work_done = 0; + + priv = netdev_priv(dev); + vq = priv->vqs[VIRTIO_CAN_QUEUE_RX]; + + 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 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; + + 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..7cf613bb3f1a --- /dev/null +++ b/include/uapi/linux/virtio_can.h @@ -0,0 +1,75 @@ +/* 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 + +/* 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 + +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[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 */ + __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[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 */ -- 2.43.0
