OSCL-LXR linux-6.0.1/​drivers/​net/​can/​usb/​etas_es58x/​es58x_core.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 
 /* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
  *
  * File es58x_core.c: Core logic to manage the network devices and the
  * USB interface.
  *
  * Copyright (c) 2019 Robert Bosch Engineering and Business Solutions. All rights reserved.
  * Copyright (c) 2020 ETAS K.K.. All rights reserved.
  * Copyright (c) 2020, 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
  */
 
 #include <linux/ethtool.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/usb.h>
 #include <linux/crc16.h>
 #include <asm/unaligned.h>
 
 #include "es58x_core.h"
 
 MODULE_AUTHOR("Vincent Mailhol <mailhol.vincent@wanadoo.fr>");
 MODULE_AUTHOR("Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com>");
 MODULE_DESCRIPTION("Socket CAN driver for ETAS ES58X USB adapters");
 MODULE_LICENSE("GPL v2");
 
 #define ES58X_VENDOR_ID 0x108C
 #define ES581_4_PRODUCT_ID 0x0159
 #define ES582_1_PRODUCT_ID 0x0168
 #define ES584_1_PRODUCT_ID 0x0169
 
 /* ES58X FD has some interface protocols unsupported by this driver. */
 #define ES58X_FD_INTERFACE_PROTOCOL 0
 
 /* Table of devices which work with this driver. */
 static const struct usb_device_id es58x_id_table[] = {
     {
         /* ETAS GmbH ES581.4 USB dual-channel CAN Bus Interface module. */
         USB_DEVICE(ES58X_VENDOR_ID, ES581_4_PRODUCT_ID),
         .driver_info = ES58X_DUAL_CHANNEL
     }, {
         /* ETAS GmbH ES582.1 USB dual-channel CAN FD Bus Interface module. */
         USB_DEVICE_INTERFACE_PROTOCOL(ES58X_VENDOR_ID, ES582_1_PRODUCT_ID,
                           ES58X_FD_INTERFACE_PROTOCOL),
         .driver_info = ES58X_DUAL_CHANNEL | ES58X_FD_FAMILY
     }, {
         /* ETAS GmbH ES584.1 USB single-channel CAN FD Bus Interface module. */
         USB_DEVICE_INTERFACE_PROTOCOL(ES58X_VENDOR_ID, ES584_1_PRODUCT_ID,
                           ES58X_FD_INTERFACE_PROTOCOL),
         .driver_info = ES58X_FD_FAMILY
     }, {
         /* Terminating entry */
     }
 };
 
 MODULE_DEVICE_TABLE(usb, es58x_id_table);
 
 #define es58x_print_hex_dump(buf, len)                  \
     print_hex_dump(KERN_DEBUG,                  \
                KBUILD_MODNAME " " __stringify(buf) ": ",    \
                DUMP_PREFIX_NONE, 16, 1, buf, len, false)
 
 #define es58x_print_hex_dump_debug(buf, len)                 \
     print_hex_dump_debug(KBUILD_MODNAME " " __stringify(buf) ": ",\
                  DUMP_PREFIX_NONE, 16, 1, buf, len, false)
 
 /* The last two bytes of an ES58X command is a CRC16. The first two
  * bytes (the start of frame) are skipped and the CRC calculation
  * starts on the third byte.
  */
 #define ES58X_CRC_CALC_OFFSET sizeof_field(union es58x_urb_cmd, sof)
 
 /**
  * es58x_calculate_crc() - Compute the crc16 of a given URB.
  * @urb_cmd: The URB command for which we want to calculate the CRC.
  * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
  *  (ES58X_CRC_CALC_OFFSET + sizeof(crc))
  *
  * Return: crc16 value.
  */
 static u16 es58x_calculate_crc(const union es58x_urb_cmd *urb_cmd, u16 urb_len)
 {
     u16 crc;
     ssize_t len = urb_len - ES58X_CRC_CALC_OFFSET - sizeof(crc);
 
     crc = crc16(0, &urb_cmd->raw_cmd[ES58X_CRC_CALC_OFFSET], len);
     return crc;
 }
 
 /**
  * es58x_get_crc() - Get the CRC value of a given URB.
  * @urb_cmd: The URB command for which we want to get the CRC.
  * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
  *  (ES58X_CRC_CALC_OFFSET + sizeof(crc))
  *
  * Return: crc16 value.
  */
 static u16 es58x_get_crc(const union es58x_urb_cmd *urb_cmd, u16 urb_len)
 {
     u16 crc;
     const __le16 *crc_addr;
 
     crc_addr = (__le16 *)&urb_cmd->raw_cmd[urb_len - sizeof(crc)];
     crc = get_unaligned_le16(crc_addr);
     return crc;
 }
 
 /**
  * es58x_set_crc() - Set the CRC value of a given URB.
  * @urb_cmd: The URB command for which we want to get the CRC.
  * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
  *  (ES58X_CRC_CALC_OFFSET + sizeof(crc))
  */
 static void es58x_set_crc(union es58x_urb_cmd *urb_cmd, u16 urb_len)
 {
     u16 crc;
     __le16 *crc_addr;
 
     crc = es58x_calculate_crc(urb_cmd, urb_len);
     crc_addr = (__le16 *)&urb_cmd->raw_cmd[urb_len - sizeof(crc)];
     put_unaligned_le16(crc, crc_addr);
 }
 
 /**
  * es58x_check_crc() - Validate the CRC value of a given URB.
  * @es58x_dev: ES58X device.
  * @urb_cmd: The URB command for which we want to check the CRC.
  * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
  *  (ES58X_CRC_CALC_OFFSET + sizeof(crc))
  *
  * Return: zero on success, -EBADMSG if the CRC check fails.
  */
 static int es58x_check_crc(struct es58x_device *es58x_dev,
                const union es58x_urb_cmd *urb_cmd, u16 urb_len)
 {
     u16 calculated_crc = es58x_calculate_crc(urb_cmd, urb_len);
     u16 expected_crc = es58x_get_crc(urb_cmd, urb_len);
 
     if (expected_crc != calculated_crc) {
         dev_err_ratelimited(es58x_dev->dev,
                     "%s: Bad CRC, urb_len: %d\n",
                     __func__, urb_len);
         return -EBADMSG;
     }
 
     return 0;
 }
 
 /**
  * es58x_timestamp_to_ns() - Convert a timestamp value received from a
  *  ES58X device to nanoseconds.
  * @timestamp: Timestamp received from a ES58X device.
  *
  * The timestamp received from ES58X is expressed in multiples of 0.5
  * micro seconds. This function converts it in to nanoseconds.
  *
  * Return: Timestamp value in nanoseconds.
  */
 static u64 es58x_timestamp_to_ns(u64 timestamp)
 {
     const u64 es58x_timestamp_ns_mult_coef = 500ULL;
 
     return es58x_timestamp_ns_mult_coef * timestamp;
 }
 
 /**
  * es58x_set_skb_timestamp() - Set the hardware timestamp of an skb.
  * @netdev: CAN network device.
  * @skb: socket buffer of a CAN message.
  * @timestamp: Timestamp received from an ES58X device.
  *
  * Used for both received and echo messages.
  */
 static void es58x_set_skb_timestamp(struct net_device *netdev,
                     struct sk_buff *skb, u64 timestamp)
 {
     struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
     struct skb_shared_hwtstamps *hwts;
 
     hwts = skb_hwtstamps(skb);
     /* Ignoring overflow (overflow on 64 bits timestamp with nano
      * second precision would occur after more than 500 years).
      */
     hwts->hwtstamp = ns_to_ktime(es58x_timestamp_to_ns(timestamp) +
                      es58x_dev->realtime_diff_ns);
 }
 
 /**
  * es58x_rx_timestamp() - Handle a received timestamp.
  * @es58x_dev: ES58X device.
  * @timestamp: Timestamp received from a ES58X device.
  *
  * Calculate the difference between the ES58X device and the kernel
  * internal clocks. This difference will be later used as an offset to
  * convert the timestamps of RX and echo messages to match the kernel
  * system time (e.g. convert to UNIX time).
  */
 void es58x_rx_timestamp(struct es58x_device *es58x_dev, u64 timestamp)
 {
     u64 ktime_real_ns = ktime_get_real_ns();
     u64 device_timestamp = es58x_timestamp_to_ns(timestamp);
 
     dev_dbg(es58x_dev->dev, "%s: request round-trip time: %llu ns\n",
         __func__, ktime_real_ns - es58x_dev->ktime_req_ns);
 
     es58x_dev->realtime_diff_ns =
         (es58x_dev->ktime_req_ns + ktime_real_ns) / 2 - device_timestamp;
     es58x_dev->ktime_req_ns = 0;
 
     dev_dbg(es58x_dev->dev,
         "%s: Device timestamp: %llu, diff with kernel: %llu\n",
         __func__, device_timestamp, es58x_dev->realtime_diff_ns);
 }
 
 /**
  * es58x_set_realtime_diff_ns() - Calculate difference between the
  *  clocks of the ES58X device and the kernel
  * @es58x_dev: ES58X device.
  *
  * Request a timestamp from the ES58X device. Once the answer is
  * received, the timestamp difference will be set by the callback
  * function es58x_rx_timestamp().
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_set_realtime_diff_ns(struct es58x_device *es58x_dev)
 {
     if (es58x_dev->ktime_req_ns) {
         dev_warn(es58x_dev->dev,
              "%s: Previous request to set timestamp has not completed yet\n",
              __func__);
         return -EBUSY;
     }
 
     es58x_dev->ktime_req_ns = ktime_get_real_ns();
     return es58x_dev->ops->get_timestamp(es58x_dev);
 }
 
 /**
  * es58x_is_can_state_active() - Is the network device in an active
  *  CAN state?
  * @netdev: CAN network device.
  *
  * The device is considered active if it is able to send or receive
  * CAN frames, that is to say if it is in any of
  * CAN_STATE_ERROR_ACTIVE, CAN_STATE_ERROR_WARNING or
  * CAN_STATE_ERROR_PASSIVE states.
  *
  * Caution: when recovering from a bus-off,
  * net/core/dev.c#can_restart() will call
  * net/core/dev.c#can_flush_echo_skb() without using any kind of
  * locks. For this reason, it is critical to guarantee that no TX or
  * echo operations (i.e. any access to priv->echo_skb[]) can be done
  * while this function is returning false.
  *
  * Return: true if the device is active, else returns false.
  */
 static bool es58x_is_can_state_active(struct net_device *netdev)
 {
     return es58x_priv(netdev)->can.state < CAN_STATE_BUS_OFF;
 }
 
 /**
  * es58x_is_echo_skb_threshold_reached() - Determine the limit of how
  *  many skb slots can be taken before we should stop the network
  *  queue.
  * @priv: ES58X private parameters related to the network device.
  *
  * We need to save enough free skb slots in order to be able to do
  * bulk send. This function can be used to determine when to wake or
  * stop the network queue in regard to the number of skb slots already
  * taken if the echo FIFO.
  *
  * Return: boolean.
  */
 static bool es58x_is_echo_skb_threshold_reached(struct es58x_priv *priv)
 {
     u32 num_echo_skb =  priv->tx_head - priv->tx_tail;
     u32 threshold = priv->can.echo_skb_max -
         priv->es58x_dev->param->tx_bulk_max + 1;
 
     return num_echo_skb >= threshold;
 }
 
 /**
  * es58x_can_free_echo_skb_tail() - Remove the oldest echo skb of the
  *  echo FIFO.
  * @netdev: CAN network device.
  *
  * Naming convention: the tail is the beginning of the FIFO, i.e. the
  * first skb to have entered the FIFO.
  */
 static void es58x_can_free_echo_skb_tail(struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     u16 fifo_mask = priv->es58x_dev->param->fifo_mask;
     unsigned int frame_len = 0;
 
     can_free_echo_skb(netdev, priv->tx_tail & fifo_mask, &frame_len);
     netdev_completed_queue(netdev, 1, frame_len);
 
     priv->tx_tail++;
 
     netdev->stats.tx_dropped++;
 }
 
 /**
  * es58x_can_get_echo_skb_recovery() - Try to re-sync the echo FIFO.
  * @netdev: CAN network device.
  * @rcv_packet_idx: Index
  *
  * This function should not be called under normal circumstances. In
  * the unlikely case that one or several URB packages get dropped by
  * the device, the index will get out of sync. Try to recover by
  * dropping the echo skb packets with older indexes.
  *
  * Return: zero if recovery was successful, -EINVAL otherwise.
  */
 static int es58x_can_get_echo_skb_recovery(struct net_device *netdev,
                        u32 rcv_packet_idx)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     int ret = 0;
 
     netdev->stats.tx_errors++;
 
     if (net_ratelimit())
         netdev_warn(netdev,
                 "Bad echo packet index: %u. First index: %u, end index %u, num_echo_skb: %02u/%02u\n",
                 rcv_packet_idx, priv->tx_tail, priv->tx_head,
                 priv->tx_head - priv->tx_tail,
                 priv->can.echo_skb_max);
 
     if ((s32)(rcv_packet_idx - priv->tx_tail) < 0) {
         if (net_ratelimit())
             netdev_warn(netdev,
                     "Received echo index is from the past. Ignoring it\n");
         ret = -EINVAL;
     } else if ((s32)(rcv_packet_idx - priv->tx_head) >= 0) {
         if (net_ratelimit())
             netdev_err(netdev,
                    "Received echo index is from the future. Ignoring it\n");
         ret = -EINVAL;
     } else {
         if (net_ratelimit())
             netdev_warn(netdev,
                     "Recovery: dropping %u echo skb from index %u to %u\n",
                     rcv_packet_idx - priv->tx_tail,
                     priv->tx_tail, rcv_packet_idx - 1);
         while (priv->tx_tail != rcv_packet_idx) {
             if (priv->tx_tail == priv->tx_head)
                 return -EINVAL;
             es58x_can_free_echo_skb_tail(netdev);
         }
     }
     return ret;
 }
 
 /**
  * es58x_can_get_echo_skb() - Get the skb from the echo FIFO and loop
  *  it back locally.
  * @netdev: CAN network device.
  * @rcv_packet_idx: Index of the first packet received from the device.
  * @tstamps: Array of hardware timestamps received from a ES58X device.
  * @pkts: Number of packets (and so, length of @tstamps).
  *
  * Callback function for when we receive a self reception
  * acknowledgment.  Retrieves the skb from the echo FIFO, sets its
  * hardware timestamp (the actual time it was sent) and loops it back
  * locally.
  *
  * The device has to be active (i.e. network interface UP and not in
  * bus off state or restarting).
  *
  * Packet indexes must be consecutive (i.e. index of first packet is
  * @rcv_packet_idx, index of second packet is @rcv_packet_idx + 1 and
  * index of last packet is @rcv_packet_idx + @pkts - 1).
  *
  * Return: zero on success.
  */
 int es58x_can_get_echo_skb(struct net_device *netdev, u32 rcv_packet_idx,
                u64 *tstamps, unsigned int pkts)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     unsigned int rx_total_frame_len = 0;
     unsigned int num_echo_skb = priv->tx_head - priv->tx_tail;
     int i;
     u16 fifo_mask = priv->es58x_dev->param->fifo_mask;
 
     if (!netif_running(netdev)) {
         if (net_ratelimit())
             netdev_info(netdev,
                     "%s: %s is down, dropping %d echo packets\n",
                     __func__, netdev->name, pkts);
         netdev->stats.tx_dropped += pkts;
         return 0;
     } else if (!es58x_is_can_state_active(netdev)) {
         if (net_ratelimit())
             netdev_dbg(netdev,
                    "Bus is off or device is restarting. Ignoring %u echo packets from index %u\n",
                    pkts, rcv_packet_idx);
         /* stats.tx_dropped will be (or was already)
          * incremented by
          * drivers/net/can/net/dev.c:can_flush_echo_skb().
          */
         return 0;
     } else if (num_echo_skb == 0) {
         if (net_ratelimit())
             netdev_warn(netdev,
                     "Received %u echo packets from index: %u but echo skb queue is empty.\n",
                     pkts, rcv_packet_idx);
         netdev->stats.tx_dropped += pkts;
         return 0;
     }
 
     if (priv->tx_tail != rcv_packet_idx) {
         if (es58x_can_get_echo_skb_recovery(netdev, rcv_packet_idx) < 0) {
             if (net_ratelimit())
                 netdev_warn(netdev,
                         "Could not find echo skb for echo packet index: %u\n",
                         rcv_packet_idx);
             return 0;
         }
     }
     if (num_echo_skb < pkts) {
         int pkts_drop = pkts - num_echo_skb;
 
         if (net_ratelimit())
             netdev_err(netdev,
                    "Received %u echo packets but have only %d echo skb. Dropping %d echo skb\n",
                    pkts, num_echo_skb, pkts_drop);
         netdev->stats.tx_dropped += pkts_drop;
         pkts -= pkts_drop;
     }
 
     for (i = 0; i < pkts; i++) {
         unsigned int skb_idx = priv->tx_tail & fifo_mask;
         struct sk_buff *skb = priv->can.echo_skb[skb_idx];
         unsigned int frame_len = 0;
 
         if (skb)
             es58x_set_skb_timestamp(netdev, skb, tstamps[i]);
 
         netdev->stats.tx_bytes += can_get_echo_skb(netdev, skb_idx,
                                &frame_len);
         rx_total_frame_len += frame_len;
 
         priv->tx_tail++;
     }
 
     netdev_completed_queue(netdev, pkts, rx_total_frame_len);
     netdev->stats.tx_packets += pkts;
 
     priv->err_passive_before_rtx_success = 0;
     if (!es58x_is_echo_skb_threshold_reached(priv))
         netif_wake_queue(netdev);
 
     return 0;
 }
 
 /**
  * es58x_can_reset_echo_fifo() - Reset the echo FIFO.
  * @netdev: CAN network device.
  *
  * The echo_skb array of struct can_priv will be flushed by
  * drivers/net/can/dev.c:can_flush_echo_skb(). This function resets
  * the parameters of the struct es58x_priv of our device and reset the
  * queue (c.f. BQL).
  */
 static void es58x_can_reset_echo_fifo(struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
 
     priv->tx_tail = 0;
     priv->tx_head = 0;
     priv->tx_urb = NULL;
     priv->err_passive_before_rtx_success = 0;
     netdev_reset_queue(netdev);
 }
 
 /**
  * es58x_flush_pending_tx_msg() - Reset the buffer for transmission messages.
  * @netdev: CAN network device.
  *
  * es58x_start_xmit() will queue up to tx_bulk_max messages in
  * &tx_urb buffer and do a bulk send of all messages in one single URB
  * (c.f. xmit_more flag). When the device recovers from a bus off
  * state or when the device stops, the tx_urb buffer might still have
  * pending messages in it and thus need to be flushed.
  */
 static void es58x_flush_pending_tx_msg(struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     struct es58x_device *es58x_dev = priv->es58x_dev;
 
     if (priv->tx_urb) {
         netdev_warn(netdev, "%s: dropping %d TX messages\n",
                 __func__, priv->tx_can_msg_cnt);
         netdev->stats.tx_dropped += priv->tx_can_msg_cnt;
         while (priv->tx_can_msg_cnt > 0) {
             unsigned int frame_len = 0;
             u16 fifo_mask = priv->es58x_dev->param->fifo_mask;
 
             priv->tx_head--;
             priv->tx_can_msg_cnt--;
             can_free_echo_skb(netdev, priv->tx_head & fifo_mask,
                       &frame_len);
             netdev_completed_queue(netdev, 1, frame_len);
         }
         usb_anchor_urb(priv->tx_urb, &priv->es58x_dev->tx_urbs_idle);
         atomic_inc(&es58x_dev->tx_urbs_idle_cnt);
         usb_free_urb(priv->tx_urb);
     }
     priv->tx_urb = NULL;
 }
 
 /**
  * es58x_tx_ack_msg() - Handle acknowledgment messages.
  * @netdev: CAN network device.
  * @tx_free_entries: Number of free entries in the device transmit FIFO.
  * @rx_cmd_ret_u32: error code as returned by the ES58X device.
  *
  * ES58X sends an acknowledgment message after a transmission request
  * is done. This is mandatory for the ES581.4 but is optional (and
  * deactivated in this driver) for the ES58X_FD family.
  *
  * Under normal circumstances, this function should never throw an
  * error message.
  *
  * Return: zero on success, errno when any error occurs.
  */
 int es58x_tx_ack_msg(struct net_device *netdev, u16 tx_free_entries,
              enum es58x_ret_u32 rx_cmd_ret_u32)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
 
     if (tx_free_entries <= priv->es58x_dev->param->tx_bulk_max) {
         if (net_ratelimit())
             netdev_err(netdev,
                    "Only %d entries left in device queue, num_echo_skb: %d/%d\n",
                    tx_free_entries,
                    priv->tx_head - priv->tx_tail,
                    priv->can.echo_skb_max);
         netif_stop_queue(netdev);
     }
 
     return es58x_rx_cmd_ret_u32(netdev, ES58X_RET_TYPE_TX_MSG,
                     rx_cmd_ret_u32);
 }
 
 /**
  * es58x_rx_can_msg() - Handle a received a CAN message.
  * @netdev: CAN network device.
  * @timestamp: Hardware time stamp (only relevant in rx branches).
  * @data: CAN payload.
  * @can_id: CAN ID.
  * @es58x_flags: Please refer to enum es58x_flag.
  * @dlc: Data Length Code (raw value).
  *
  * Fill up a CAN skb and post it.
  *
  * This function handles the case where the DLC of a classical CAN
  * frame is greater than CAN_MAX_DLEN (c.f. the len8_dlc field of
  * struct can_frame).
  *
  * Return: zero on success.
  */
 int es58x_rx_can_msg(struct net_device *netdev, u64 timestamp, const u8 *data,
              canid_t can_id, enum es58x_flag es58x_flags, u8 dlc)
 {
     struct canfd_frame *cfd;
     struct can_frame *ccf;
     struct sk_buff *skb;
     u8 len;
     bool is_can_fd = !!(es58x_flags & ES58X_FLAG_FD_DATA);
 
     if (dlc > CAN_MAX_RAW_DLC) {
         netdev_err(netdev,
                "%s: DLC is %d but maximum should be %d\n",
                __func__, dlc, CAN_MAX_RAW_DLC);
         return -EMSGSIZE;
     }
 
     if (is_can_fd) {
         len = can_fd_dlc2len(dlc);
         skb = alloc_canfd_skb(netdev, &cfd);
     } else {
         len = can_cc_dlc2len(dlc);
         skb = alloc_can_skb(netdev, &ccf);
         cfd = (struct canfd_frame *)ccf;
     }
     if (!skb) {
         netdev->stats.rx_dropped++;
         return 0;
     }
 
     cfd->can_id = can_id;
     if (es58x_flags & ES58X_FLAG_EFF)
         cfd->can_id |= CAN_EFF_FLAG;
     if (is_can_fd) {
         cfd->len = len;
         if (es58x_flags & ES58X_FLAG_FD_BRS)
             cfd->flags |= CANFD_BRS;
         if (es58x_flags & ES58X_FLAG_FD_ESI)
             cfd->flags |= CANFD_ESI;
     } else {
         can_frame_set_cc_len(ccf, dlc, es58x_priv(netdev)->can.ctrlmode);
         if (es58x_flags & ES58X_FLAG_RTR) {
             ccf->can_id |= CAN_RTR_FLAG;
             len = 0;
         }
     }
     memcpy(cfd->data, data, len);
     netdev->stats.rx_packets++;
     netdev->stats.rx_bytes += len;
 
     es58x_set_skb_timestamp(netdev, skb, timestamp);
     netif_rx(skb);
 
     es58x_priv(netdev)->err_passive_before_rtx_success = 0;
 
     return 0;
 }
 
 /**
  * es58x_rx_err_msg() - Handle a received CAN event or error message.
  * @netdev: CAN network device.
  * @error: Error code.
  * @event: Event code.
  * @timestamp: Timestamp received from a ES58X device.
  *
  * Handle the errors and events received by the ES58X device, create
  * a CAN error skb and post it.
  *
  * In some rare cases the devices might get stuck alternating between
  * CAN_STATE_ERROR_PASSIVE and CAN_STATE_ERROR_WARNING. To prevent
  * this behavior, we force a bus off state if the device goes in
  * CAN_STATE_ERROR_WARNING for ES58X_MAX_CONSECUTIVE_WARN consecutive
  * times with no successful transmission or reception in between.
  *
  * Once the device is in bus off state, the only way to restart it is
  * through the drivers/net/can/dev.c:can_restart() function. The
  * device is technically capable to recover by itself under certain
  * circumstances, however, allowing self recovery would create
  * complex race conditions with drivers/net/can/dev.c:can_restart()
  * and thus was not implemented. To activate automatic restart, please
  * set the restart-ms parameter (e.g. ip link set can0 type can
  * restart-ms 100).
  *
  * If the bus is really instable, this function would try to send a
  * lot of log messages. Those are rate limited (i.e. you will see
  * messages such as "net_ratelimit: XXX callbacks suppressed" in
  * dmesg).
  *
  * Return: zero on success, errno when any error occurs.
  */
 int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error,
              enum es58x_event event, u64 timestamp)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     struct can_priv *can = netdev_priv(netdev);
     struct can_device_stats *can_stats = &can->can_stats;
     struct can_frame *cf = NULL;
     struct sk_buff *skb;
     int ret = 0;
 
     if (!netif_running(netdev)) {
         if (net_ratelimit())
             netdev_info(netdev, "%s: %s is down, dropping packet\n",
                     __func__, netdev->name);
         netdev->stats.rx_dropped++;
         return 0;
     }
 
     if (error == ES58X_ERR_OK && event == ES58X_EVENT_OK) {
         netdev_err(netdev, "%s: Both error and event are zero\n",
                __func__);
         return -EINVAL;
     }
 
     skb = alloc_can_err_skb(netdev, &cf);
 
     switch (error) {
     case ES58X_ERR_OK:  /* 0: No error */
         break;
 
     case ES58X_ERR_PROT_STUFF:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error BITSTUFF\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_STUFF;
         break;
 
     case ES58X_ERR_PROT_FORM:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error FORMAT\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_FORM;
         break;
 
     case ES58X_ERR_ACK:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error ACK\n");
         if (cf)
             cf->can_id |= CAN_ERR_ACK;
         break;
 
     case ES58X_ERR_PROT_BIT:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error BIT\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_BIT;
         break;
 
     case ES58X_ERR_PROT_CRC:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error CRC\n");
         if (cf)
             cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
         break;
 
     case ES58X_ERR_PROT_BIT1:
         if (net_ratelimit())
             netdev_dbg(netdev,
                    "Error: expected a recessive bit but monitored a dominant one\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_BIT1;
         break;
 
     case ES58X_ERR_PROT_BIT0:
         if (net_ratelimit())
             netdev_dbg(netdev,
                    "Error expected a dominant bit but monitored a recessive one\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_BIT0;
         break;
 
     case ES58X_ERR_PROT_OVERLOAD:
         if (net_ratelimit())
             netdev_dbg(netdev, "Error OVERLOAD\n");
         if (cf)
             cf->data[2] |= CAN_ERR_PROT_OVERLOAD;
         break;
 
     case ES58X_ERR_PROT_UNSPEC:
         if (net_ratelimit())
             netdev_dbg(netdev, "Unspecified error\n");
         if (cf)
             cf->can_id |= CAN_ERR_PROT;
         break;
 
     default:
         if (net_ratelimit())
             netdev_err(netdev,
                    "%s: Unspecified error code 0x%04X\n",
                    __func__, (int)error);
         if (cf)
             cf->can_id |= CAN_ERR_PROT;
         break;
     }
 
     switch (event) {
     case ES58X_EVENT_OK:    /* 0: No event */
         break;
 
     case ES58X_EVENT_CRTL_ACTIVE:
         if (can->state == CAN_STATE_BUS_OFF) {
             netdev_err(netdev,
                    "%s: state transition: BUS OFF -> ACTIVE\n",
                    __func__);
         }
         if (net_ratelimit())
             netdev_dbg(netdev, "Event CAN BUS ACTIVE\n");
         if (cf)
             cf->data[1] |= CAN_ERR_CRTL_ACTIVE;
         can->state = CAN_STATE_ERROR_ACTIVE;
         break;
 
     case ES58X_EVENT_CRTL_PASSIVE:
         if (net_ratelimit())
             netdev_dbg(netdev, "Event CAN BUS PASSIVE\n");
         /* Either TX or RX error count reached passive state
          * but we do not know which. Setting both flags by
          * default.
          */
         if (cf) {
             cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
             cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
         }
         if (can->state < CAN_STATE_BUS_OFF)
             can->state = CAN_STATE_ERROR_PASSIVE;
         can_stats->error_passive++;
         if (priv->err_passive_before_rtx_success < U8_MAX)
             priv->err_passive_before_rtx_success++;
         break;
 
     case ES58X_EVENT_CRTL_WARNING:
         if (net_ratelimit())
             netdev_dbg(netdev, "Event CAN BUS WARNING\n");
         /* Either TX or RX error count reached warning state
          * but we do not know which. Setting both flags by
          * default.
          */
         if (cf) {
             cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
             cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;
         }
         if (can->state < CAN_STATE_BUS_OFF)
             can->state = CAN_STATE_ERROR_WARNING;
         can_stats->error_warning++;
         break;
 
     case ES58X_EVENT_BUSOFF:
         if (net_ratelimit())
             netdev_dbg(netdev, "Event CAN BUS OFF\n");
         if (cf)
             cf->can_id |= CAN_ERR_BUSOFF;
         can_stats->bus_off++;
         netif_stop_queue(netdev);
         if (can->state != CAN_STATE_BUS_OFF) {
             can->state = CAN_STATE_BUS_OFF;
             can_bus_off(netdev);
             ret = can->do_set_mode(netdev, CAN_MODE_STOP);
         }
         break;
 
     case ES58X_EVENT_SINGLE_WIRE:
         if (net_ratelimit())
             netdev_warn(netdev,
                     "Lost connection on either CAN high or CAN low\n");
         /* Lost connection on either CAN high or CAN
          * low. Setting both flags by default.
          */
         if (cf) {
             cf->data[4] |= CAN_ERR_TRX_CANH_NO_WIRE;
             cf->data[4] |= CAN_ERR_TRX_CANL_NO_WIRE;
         }
         break;
 
     default:
         if (net_ratelimit())
             netdev_err(netdev,
                    "%s: Unspecified event code 0x%04X\n",
                    __func__, (int)event);
         if (cf)
             cf->can_id |= CAN_ERR_CRTL;
         break;
     }
 
     if (cf) {
         if (cf->data[1])
             cf->can_id |= CAN_ERR_CRTL;
         if (cf->data[2] || cf->data[3]) {
             cf->can_id |= CAN_ERR_PROT;
             can_stats->bus_error++;
         }
         if (cf->data[4])
             cf->can_id |= CAN_ERR_TRX;
 
         es58x_set_skb_timestamp(netdev, skb, timestamp);
         netif_rx(skb);
     }
 
     if ((event & ES58X_EVENT_CRTL_PASSIVE) &&
         priv->err_passive_before_rtx_success == ES58X_CONSECUTIVE_ERR_PASSIVE_MAX) {
         netdev_info(netdev,
                 "Got %d consecutive warning events with no successful RX or TX. Forcing bus-off\n",
                 priv->err_passive_before_rtx_success);
         return es58x_rx_err_msg(netdev, ES58X_ERR_OK,
                     ES58X_EVENT_BUSOFF, timestamp);
     }
 
     return ret;
 }
 
 /**
  * es58x_cmd_ret_desc() - Convert a command type to a string.
  * @cmd_ret_type: Type of the command which triggered the return code.
  *
  * The final line (return "<unknown>") should not be reached. If this
  * is the case, there is an implementation bug.
  *
  * Return: a readable description of the @cmd_ret_type.
  */
 static const char *es58x_cmd_ret_desc(enum es58x_ret_type cmd_ret_type)
 {
     switch (cmd_ret_type) {
     case ES58X_RET_TYPE_SET_BITTIMING:
         return "Set bittiming";
     case ES58X_RET_TYPE_ENABLE_CHANNEL:
         return "Enable channel";
     case ES58X_RET_TYPE_DISABLE_CHANNEL:
         return "Disable channel";
     case ES58X_RET_TYPE_TX_MSG:
         return "Transmit message";
     case ES58X_RET_TYPE_RESET_RX:
         return "Reset RX";
     case ES58X_RET_TYPE_RESET_TX:
         return "Reset TX";
     case ES58X_RET_TYPE_DEVICE_ERR:
         return "Device error";
     }
 
     return "<unknown>";
 };
 
 /**
  * es58x_rx_cmd_ret_u8() - Handle the command's return code received
  *  from the ES58X device.
  * @dev: Device, only used for the dev_XXX() print functions.
  * @cmd_ret_type: Type of the command which triggered the return code.
  * @rx_cmd_ret_u8: Command error code as returned by the ES58X device.
  *
  * Handles the 8 bits command return code. Those are specific to the
  * ES581.4 device. The return value will eventually be used by
  * es58x_handle_urb_cmd() function which will take proper actions in
  * case of critical issues such and memory errors or bad CRC values.
  *
  * In contrast with es58x_rx_cmd_ret_u32(), the network device is
  * unknown.
  *
  * Return: zero on success, return errno when any error occurs.
  */
 int es58x_rx_cmd_ret_u8(struct device *dev,
             enum es58x_ret_type cmd_ret_type,
             enum es58x_ret_u8 rx_cmd_ret_u8)
 {
     const char *ret_desc = es58x_cmd_ret_desc(cmd_ret_type);
 
     switch (rx_cmd_ret_u8) {
     case ES58X_RET_U8_OK:
         dev_dbg_ratelimited(dev, "%s: OK\n", ret_desc);
         return 0;
 
     case ES58X_RET_U8_ERR_UNSPECIFIED_FAILURE:
         dev_err(dev, "%s: unspecified failure\n", ret_desc);
         return -EBADMSG;
 
     case ES58X_RET_U8_ERR_NO_MEM:
         dev_err(dev, "%s: device ran out of memory\n", ret_desc);
         return -ENOMEM;
 
     case ES58X_RET_U8_ERR_BAD_CRC:
         dev_err(dev, "%s: CRC of previous command is incorrect\n",
             ret_desc);
         return -EIO;
 
     default:
         dev_err(dev, "%s: returned unknown value: 0x%02X\n",
             ret_desc, rx_cmd_ret_u8);
         return -EBADMSG;
     }
 }
 
 /**
  * es58x_rx_cmd_ret_u32() - Handle the command return code received
  *  from the ES58X device.
  * @netdev: CAN network device.
  * @cmd_ret_type: Type of the command which triggered the return code.
  * @rx_cmd_ret_u32: error code as returned by the ES58X device.
  *
  * Handles the 32 bits command return code. The return value will
  * eventually be used by es58x_handle_urb_cmd() function which will
  * take proper actions in case of critical issues such and memory
  * errors or bad CRC values.
  *
  * Return: zero on success, errno when any error occurs.
  */
 int es58x_rx_cmd_ret_u32(struct net_device *netdev,
              enum es58x_ret_type cmd_ret_type,
              enum es58x_ret_u32 rx_cmd_ret_u32)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     const struct es58x_operators *ops = priv->es58x_dev->ops;
     const char *ret_desc = es58x_cmd_ret_desc(cmd_ret_type);
 
     switch (rx_cmd_ret_u32) {
     case ES58X_RET_U32_OK:
         switch (cmd_ret_type) {
         case ES58X_RET_TYPE_ENABLE_CHANNEL:
             es58x_can_reset_echo_fifo(netdev);
             priv->can.state = CAN_STATE_ERROR_ACTIVE;
             netif_wake_queue(netdev);
             netdev_info(netdev,
                     "%s: %s (Serial Number %s): CAN%d channel becomes ready\n",
                     ret_desc, priv->es58x_dev->udev->product,
                     priv->es58x_dev->udev->serial,
                     priv->channel_idx + 1);
             break;
 
         case ES58X_RET_TYPE_TX_MSG:
             if (IS_ENABLED(CONFIG_VERBOSE_DEBUG) && net_ratelimit())
                 netdev_vdbg(netdev, "%s: OK\n", ret_desc);
             break;
 
         default:
             netdev_dbg(netdev, "%s: OK\n", ret_desc);
             break;
         }
         return 0;
 
     case ES58X_RET_U32_ERR_UNSPECIFIED_FAILURE:
         if (cmd_ret_type == ES58X_RET_TYPE_ENABLE_CHANNEL) {
             int ret;
 
             netdev_warn(netdev,
                     "%s: channel is already opened, closing and re-opening it to reflect new configuration\n",
                     ret_desc);
             ret = ops->disable_channel(es58x_priv(netdev));
             if (ret)
                 return ret;
             return ops->enable_channel(es58x_priv(netdev));
         }
         if (cmd_ret_type == ES58X_RET_TYPE_DISABLE_CHANNEL) {
             netdev_info(netdev,
                     "%s: channel is already closed\n", ret_desc);
             return 0;
         }
         netdev_err(netdev,
                "%s: unspecified failure\n", ret_desc);
         return -EBADMSG;
 
     case ES58X_RET_U32_ERR_NO_MEM:
         netdev_err(netdev, "%s: device ran out of memory\n", ret_desc);
         return -ENOMEM;
 
     case ES58X_RET_U32_WARN_PARAM_ADJUSTED:
         netdev_warn(netdev,
                 "%s: some incompatible parameters have been adjusted\n",
                 ret_desc);
         return 0;
 
     case ES58X_RET_U32_WARN_TX_MAYBE_REORDER:
         netdev_warn(netdev,
                 "%s: TX messages might have been reordered\n",
                 ret_desc);
         return 0;
 
     case ES58X_RET_U32_ERR_TIMEDOUT:
         netdev_err(netdev, "%s: command timed out\n", ret_desc);
         return -ETIMEDOUT;
 
     case ES58X_RET_U32_ERR_FIFO_FULL:
         netdev_warn(netdev, "%s: fifo is full\n", ret_desc);
         return 0;
 
     case ES58X_RET_U32_ERR_BAD_CONFIG:
         netdev_err(netdev, "%s: bad configuration\n", ret_desc);
         return -EINVAL;
 
     case ES58X_RET_U32_ERR_NO_RESOURCE:
         netdev_err(netdev, "%s: no resource available\n", ret_desc);
         return -EBUSY;
 
     default:
         netdev_err(netdev, "%s returned unknown value: 0x%08X\n",
                ret_desc, rx_cmd_ret_u32);
         return -EBADMSG;
     }
 }
 
 /**
  * es58x_increment_rx_errors() - Increment the network devices' error
  *  count.
  * @es58x_dev: ES58X device.
  *
  * If an error occurs on the early stages on receiving an URB command,
  * we might not be able to figure out on which network device the
  * error occurred. In such case, we arbitrarily increment the error
  * count of all the network devices attached to our ES58X device.
  */
 static void es58x_increment_rx_errors(struct es58x_device *es58x_dev)
 {
     int i;
 
     for (i = 0; i < es58x_dev->num_can_ch; i++)
         if (es58x_dev->netdev[i])
             es58x_dev->netdev[i]->stats.rx_errors++;
 }
 
 /**
  * es58x_handle_urb_cmd() - Handle the URB command
  * @es58x_dev: ES58X device.
  * @urb_cmd: The URB command received from the ES58X device, might not
  *  be aligned.
  *
  * Sends the URB command to the device specific function. Manages the
  * errors thrown back by those functions.
  */
 static void es58x_handle_urb_cmd(struct es58x_device *es58x_dev,
                  const union es58x_urb_cmd *urb_cmd)
 {
     const struct es58x_operators *ops = es58x_dev->ops;
     size_t cmd_len;
     int i, ret;
 
     ret = ops->handle_urb_cmd(es58x_dev, urb_cmd);
     switch (ret) {
     case 0:     /* OK */
         return;
 
     case -ENODEV:
         dev_err_ratelimited(es58x_dev->dev, "Device is not ready\n");
         break;
 
     case -EINVAL:
     case -EMSGSIZE:
     case -EBADRQC:
     case -EBADMSG:
     case -ECHRNG:
     case -ETIMEDOUT:
         cmd_len = es58x_get_urb_cmd_len(es58x_dev,
                         ops->get_msg_len(urb_cmd));
         dev_err(es58x_dev->dev,
             "ops->handle_urb_cmd() returned error %pe",
             ERR_PTR(ret));
         es58x_print_hex_dump(urb_cmd, cmd_len);
         break;
 
     case -EFAULT:
     case -ENOMEM:
     case -EIO:
     default:
         dev_crit(es58x_dev->dev,
              "ops->handle_urb_cmd() returned error %pe, detaching all network devices\n",
              ERR_PTR(ret));
         for (i = 0; i < es58x_dev->num_can_ch; i++)
             if (es58x_dev->netdev[i])
                 netif_device_detach(es58x_dev->netdev[i]);
         if (es58x_dev->ops->reset_device)
             es58x_dev->ops->reset_device(es58x_dev);
         break;
     }
 
     /* Because the urb command could not fully be parsed,
      * channel_id is not confirmed. Incrementing rx_errors count
      * of all channels.
      */
     es58x_increment_rx_errors(es58x_dev);
 }
 
 /**
  * es58x_check_rx_urb() - Check the length and format of the URB command.
  * @es58x_dev: ES58X device.
  * @urb_cmd: The URB command received from the ES58X device, might not
  *  be aligned.
  * @urb_actual_len: The actual length of the URB command.
  *
  * Check if the first message of the received urb is valid, that is to
  * say that both the header and the length are coherent.
  *
  * Return:
  * the length of the first message of the URB on success.
  *
  * -ENODATA if the URB command is incomplete (in which case, the URB
  * command should be buffered and combined with the next URB to try to
  * reconstitute the URB command).
  *
  * -EOVERFLOW if the length is bigger than the maximum expected one.
  *
  * -EBADRQC if the start of frame does not match the expected value.
  */
 static signed int es58x_check_rx_urb(struct es58x_device *es58x_dev,
                      const union es58x_urb_cmd *urb_cmd,
                      u32 urb_actual_len)
 {
     const struct device *dev = es58x_dev->dev;
     const struct es58x_parameters *param = es58x_dev->param;
     u16 sof, msg_len;
     signed int urb_cmd_len, ret;
 
     if (urb_actual_len < param->urb_cmd_header_len) {
         dev_vdbg(dev,
              "%s: Received %d bytes [%*ph]: header incomplete\n",
              __func__, urb_actual_len, urb_actual_len,
              urb_cmd->raw_cmd);
         return -ENODATA;
     }
 
     sof = get_unaligned_le16(&urb_cmd->sof);
     if (sof != param->rx_start_of_frame) {
         dev_err_ratelimited(es58x_dev->dev,
                     "%s: Expected sequence 0x%04X for start of frame but got 0x%04X.\n",
                     __func__, param->rx_start_of_frame, sof);
         return -EBADRQC;
     }
 
     msg_len = es58x_dev->ops->get_msg_len(urb_cmd);
     urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
     if (urb_cmd_len > param->rx_urb_cmd_max_len) {
         dev_err_ratelimited(es58x_dev->dev,
                     "%s: Biggest expected size for rx urb_cmd is %u but receive a command of size %d\n",
                     __func__,
                     param->rx_urb_cmd_max_len, urb_cmd_len);
         return -EOVERFLOW;
     } else if (urb_actual_len < urb_cmd_len) {
         dev_vdbg(dev, "%s: Received %02d/%02d bytes\n",
              __func__, urb_actual_len, urb_cmd_len);
         return -ENODATA;
     }
 
     ret = es58x_check_crc(es58x_dev, urb_cmd, urb_cmd_len);
     if (ret)
         return ret;
 
     return urb_cmd_len;
 }
 
 /**
  * es58x_copy_to_cmd_buf() - Copy an array to the URB command buffer.
  * @es58x_dev: ES58X device.
  * @raw_cmd: the buffer we want to copy.
  * @raw_cmd_len: length of @raw_cmd.
  *
  * Concatenates @raw_cmd_len bytes of @raw_cmd to the end of the URB
  * command buffer.
  *
  * Return: zero on success, -EMSGSIZE if not enough space is available
  * to do the copy.
  */
 static int es58x_copy_to_cmd_buf(struct es58x_device *es58x_dev,
                  u8 *raw_cmd, int raw_cmd_len)
 {
     if (es58x_dev->rx_cmd_buf_len + raw_cmd_len >
         es58x_dev->param->rx_urb_cmd_max_len)
         return -EMSGSIZE;
 
     memcpy(&es58x_dev->rx_cmd_buf.raw_cmd[es58x_dev->rx_cmd_buf_len],
            raw_cmd, raw_cmd_len);
     es58x_dev->rx_cmd_buf_len += raw_cmd_len;
 
     return 0;
 }
 
 /**
  * es58x_split_urb_try_recovery() - Try to recover bad URB sequences.
  * @es58x_dev: ES58X device.
  * @raw_cmd: pointer to the buffer we want to copy.
  * @raw_cmd_len: length of @raw_cmd.
  *
  * Under some rare conditions, we might get incorrect URBs from the
  * device. From our observations, one of the valid URB gets replaced
  * by one from the past. The full root cause is not identified.
  *
  * This function looks for the next start of frame in the urb buffer
  * in order to try to recover.
  *
  * Such behavior was not observed on the devices of the ES58X FD
  * family and only seems to impact the ES581.4.
  *
  * Return: the number of bytes dropped on success, -EBADMSG if recovery failed.
  */
 static int es58x_split_urb_try_recovery(struct es58x_device *es58x_dev,
                     u8 *raw_cmd, size_t raw_cmd_len)
 {
     union es58x_urb_cmd *urb_cmd;
     signed int urb_cmd_len;
     u16 sof;
     int dropped_bytes = 0;
 
     es58x_increment_rx_errors(es58x_dev);
 
     while (raw_cmd_len > sizeof(sof)) {
         urb_cmd = (union es58x_urb_cmd *)raw_cmd;
         sof = get_unaligned_le16(&urb_cmd->sof);
 
         if (sof == es58x_dev->param->rx_start_of_frame) {
             urb_cmd_len = es58x_check_rx_urb(es58x_dev,
                              urb_cmd, raw_cmd_len);
             if ((urb_cmd_len == -ENODATA) || urb_cmd_len > 0) {
                 dev_info_ratelimited(es58x_dev->dev,
                              "Recovery successful! Dropped %d bytes (urb_cmd_len: %d)\n",
                              dropped_bytes,
                              urb_cmd_len);
                 return dropped_bytes;
             }
         }
         raw_cmd++;
         raw_cmd_len--;
         dropped_bytes++;
     }
 
     dev_warn_ratelimited(es58x_dev->dev, "%s: Recovery failed\n", __func__);
     return -EBADMSG;
 }
 
 /**
  * es58x_handle_incomplete_cmd() - Reconstitute an URB command from
  *  different URB pieces.
  * @es58x_dev: ES58X device.
  * @urb: last urb buffer received.
  *
  * The device might split the URB commands in an arbitrary amount of
  * pieces. This function concatenates those in an URB buffer until a
  * full URB command is reconstituted and consume it.
  *
  * Return:
  * number of bytes consumed from @urb if successful.
  *
  * -ENODATA if the URB command is still incomplete.
  *
  * -EBADMSG if the URB command is incorrect.
  */
 static signed int es58x_handle_incomplete_cmd(struct es58x_device *es58x_dev,
                           struct urb *urb)
 {
     size_t cpy_len;
     signed int urb_cmd_len, tmp_cmd_buf_len, ret;
 
     tmp_cmd_buf_len = es58x_dev->rx_cmd_buf_len;
     cpy_len = min_t(int, es58x_dev->param->rx_urb_cmd_max_len -
             es58x_dev->rx_cmd_buf_len, urb->actual_length);
     ret = es58x_copy_to_cmd_buf(es58x_dev, urb->transfer_buffer, cpy_len);
     if (ret < 0)
         return ret;
 
     urb_cmd_len = es58x_check_rx_urb(es58x_dev, &es58x_dev->rx_cmd_buf,
                      es58x_dev->rx_cmd_buf_len);
     if (urb_cmd_len == -ENODATA) {
         return -ENODATA;
     } else if (urb_cmd_len < 0) {
         dev_err_ratelimited(es58x_dev->dev,
                     "Could not reconstitute incomplete command from previous URB, dropping %d bytes\n",
                     tmp_cmd_buf_len + urb->actual_length);
         dev_err_ratelimited(es58x_dev->dev,
                     "Error code: %pe, es58x_dev->rx_cmd_buf_len: %d, urb->actual_length: %u\n",
                     ERR_PTR(urb_cmd_len),
                     tmp_cmd_buf_len, urb->actual_length);
         es58x_print_hex_dump(&es58x_dev->rx_cmd_buf, tmp_cmd_buf_len);
         es58x_print_hex_dump(urb->transfer_buffer, urb->actual_length);
         return urb->actual_length;
     }
 
     es58x_handle_urb_cmd(es58x_dev, &es58x_dev->rx_cmd_buf);
     return urb_cmd_len - tmp_cmd_buf_len;   /* consumed length */
 }
 
 /**
  * es58x_split_urb() - Cut the received URB in individual URB commands.
  * @es58x_dev: ES58X device.
  * @urb: last urb buffer received.
  *
  * The device might send urb in bulk format (i.e. several URB commands
  * concatenated together). This function will split all the commands
  * contained in the urb.
  *
  * Return:
  * number of bytes consumed from @urb if successful.
  *
  * -ENODATA if the URB command is incomplete.
  *
  * -EBADMSG if the URB command is incorrect.
  */
 static signed int es58x_split_urb(struct es58x_device *es58x_dev,
                   struct urb *urb)
 {
     union es58x_urb_cmd *urb_cmd;
     u8 *raw_cmd = urb->transfer_buffer;
     s32 raw_cmd_len = urb->actual_length;
     int ret;
 
     if (es58x_dev->rx_cmd_buf_len != 0) {
         ret = es58x_handle_incomplete_cmd(es58x_dev, urb);
         if (ret != -ENODATA)
             es58x_dev->rx_cmd_buf_len = 0;
         if (ret < 0)
             return ret;
 
         raw_cmd += ret;
         raw_cmd_len -= ret;
     }
 
     while (raw_cmd_len > 0) {
         if (raw_cmd[0] == ES58X_HEARTBEAT) {
             raw_cmd++;
             raw_cmd_len--;
             continue;
         }
         urb_cmd = (union es58x_urb_cmd *)raw_cmd;
         ret = es58x_check_rx_urb(es58x_dev, urb_cmd, raw_cmd_len);
         if (ret > 0) {
             es58x_handle_urb_cmd(es58x_dev, urb_cmd);
         } else if (ret == -ENODATA) {
             es58x_copy_to_cmd_buf(es58x_dev, raw_cmd, raw_cmd_len);
             return -ENODATA;
         } else if (ret < 0) {
             ret = es58x_split_urb_try_recovery(es58x_dev, raw_cmd,
                                raw_cmd_len);
             if (ret < 0)
                 return ret;
         }
         raw_cmd += ret;
         raw_cmd_len -= ret;
     }
 
     return 0;
 }
 
 /**
  * es58x_read_bulk_callback() - Callback for reading data from device.
  * @urb: last urb buffer received.
  *
  * This function gets eventually called each time an URB is received
  * from the ES58X device.
  *
  * Checks urb status, calls read function and resubmits urb read
  * operation.
  */
 static void es58x_read_bulk_callback(struct urb *urb)
 {
     struct es58x_device *es58x_dev = urb->context;
     const struct device *dev = es58x_dev->dev;
     int i, ret;
 
     switch (urb->status) {
     case 0:     /* success */
         break;
 
     case -EOVERFLOW:
         dev_err_ratelimited(dev, "%s: error %pe\n",
                     __func__, ERR_PTR(urb->status));
         es58x_print_hex_dump_debug(urb->transfer_buffer,
                        urb->transfer_buffer_length);
         goto resubmit_urb;
 
     case -EPROTO:
         dev_warn_ratelimited(dev, "%s: error %pe. Device unplugged?\n",
                      __func__, ERR_PTR(urb->status));
         goto free_urb;
 
     case -ENOENT:
     case -EPIPE:
         dev_err_ratelimited(dev, "%s: error %pe\n",
                     __func__, ERR_PTR(urb->status));
         goto free_urb;
 
     case -ESHUTDOWN:
         dev_dbg_ratelimited(dev, "%s: error %pe\n",
                     __func__, ERR_PTR(urb->status));
         goto free_urb;
 
     default:
         dev_err_ratelimited(dev, "%s: error %pe\n",
                     __func__, ERR_PTR(urb->status));
         goto resubmit_urb;
     }
 
     ret = es58x_split_urb(es58x_dev, urb);
     if ((ret != -ENODATA) && ret < 0) {
         dev_err(es58x_dev->dev, "es58x_split_urb() returned error %pe",
             ERR_PTR(ret));
         es58x_print_hex_dump_debug(urb->transfer_buffer,
                        urb->actual_length);
 
         /* Because the urb command could not be parsed,
          * channel_id is not confirmed. Incrementing rx_errors
          * count of all channels.
          */
         es58x_increment_rx_errors(es58x_dev);
     }
 
  resubmit_urb:
     ret = usb_submit_urb(urb, GFP_ATOMIC);
     if (ret == -ENODEV) {
         for (i = 0; i < es58x_dev->num_can_ch; i++)
             if (es58x_dev->netdev[i])
                 netif_device_detach(es58x_dev->netdev[i]);
     } else if (ret)
         dev_err_ratelimited(dev,
                     "Failed resubmitting read bulk urb: %pe\n",
                     ERR_PTR(ret));
     return;
 
  free_urb:
     usb_free_coherent(urb->dev, urb->transfer_buffer_length,
               urb->transfer_buffer, urb->transfer_dma);
 }
 
 /**
  * es58x_write_bulk_callback() - Callback after writing data to the device.
  * @urb: urb buffer which was previously submitted.
  *
  * This function gets eventually called each time an URB was sent to
  * the ES58X device.
  *
  * Puts the @urb back to the urbs idle anchor and tries to restart the
  * network queue.
  */
 static void es58x_write_bulk_callback(struct urb *urb)
 {
     struct net_device *netdev = urb->context;
     struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
 
     switch (urb->status) {
     case 0:     /* success */
         break;
 
     case -EOVERFLOW:
         if (net_ratelimit())
             netdev_err(netdev, "%s: error %pe\n",
                    __func__, ERR_PTR(urb->status));
         es58x_print_hex_dump(urb->transfer_buffer,
                      urb->transfer_buffer_length);
         break;
 
     case -ENOENT:
         if (net_ratelimit())
             netdev_dbg(netdev, "%s: error %pe\n",
                    __func__, ERR_PTR(urb->status));
         usb_free_coherent(urb->dev,
                   es58x_dev->param->tx_urb_cmd_max_len,
                   urb->transfer_buffer, urb->transfer_dma);
         return;
 
     default:
         if (net_ratelimit())
             netdev_info(netdev, "%s: error %pe\n",
                     __func__, ERR_PTR(urb->status));
         break;
     }
 
     usb_anchor_urb(urb, &es58x_dev->tx_urbs_idle);
     atomic_inc(&es58x_dev->tx_urbs_idle_cnt);
 }
 
 /**
  * es58x_alloc_urb() - Allocate memory for an URB and its transfer
  *  buffer.
  * @es58x_dev: ES58X device.
  * @urb: URB to be allocated.
  * @buf: used to return DMA address of buffer.
  * @buf_len: requested buffer size.
  * @mem_flags: affect whether allocation may block.
  *
  * Allocates an URB and its @transfer_buffer and set its @transfer_dma
  * address.
  *
  * This function is used at start-up to allocate all RX URBs at once
  * and during run time for TX URBs.
  *
  * Return: zero on success, -ENOMEM if no memory is available.
  */
 static int es58x_alloc_urb(struct es58x_device *es58x_dev, struct urb **urb,
                u8 **buf, size_t buf_len, gfp_t mem_flags)
 {
     *urb = usb_alloc_urb(0, mem_flags);
     if (!*urb) {
         dev_err(es58x_dev->dev, "No memory left for URBs\n");
         return -ENOMEM;
     }
 
     *buf = usb_alloc_coherent(es58x_dev->udev, buf_len,
                   mem_flags, &(*urb)->transfer_dma);
     if (!*buf) {
         dev_err(es58x_dev->dev, "No memory left for USB buffer\n");
         usb_free_urb(*urb);
         return -ENOMEM;
     }
 
     (*urb)->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
     return 0;
 }
 
 /**
  * es58x_get_tx_urb() - Get an URB for transmission.
  * @es58x_dev: ES58X device.
  *
  * Gets an URB from the idle urbs anchor or allocate a new one if the
  * anchor is empty.
  *
  * If there are more than ES58X_TX_URBS_MAX in the idle anchor, do
  * some garbage collection. The garbage collection is done here
  * instead of within es58x_write_bulk_callback() because
  * usb_free_coherent() should not be used in IRQ context:
  * c.f. WARN_ON(irqs_disabled()) in dma_free_attrs().
  *
  * Return: a pointer to an URB on success, NULL if no memory is
  * available.
  */
 static struct urb *es58x_get_tx_urb(struct es58x_device *es58x_dev)
 {
     atomic_t *idle_cnt = &es58x_dev->tx_urbs_idle_cnt;
     struct urb *urb = usb_get_from_anchor(&es58x_dev->tx_urbs_idle);
 
     if (!urb) {
         size_t tx_buf_len;
         u8 *buf;
 
         tx_buf_len = es58x_dev->param->tx_urb_cmd_max_len;
         if (es58x_alloc_urb(es58x_dev, &urb, &buf, tx_buf_len,
                     GFP_ATOMIC))
             return NULL;
 
         usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->tx_pipe,
                   buf, tx_buf_len, es58x_write_bulk_callback,
                   NULL);
         return urb;
     }
 
     while (atomic_dec_return(idle_cnt) > ES58X_TX_URBS_MAX) {
         /* Garbage collector */
         struct urb *tmp = usb_get_from_anchor(&es58x_dev->tx_urbs_idle);
 
         if (!tmp)
             break;
         usb_free_coherent(tmp->dev,
                   es58x_dev->param->tx_urb_cmd_max_len,
                   tmp->transfer_buffer, tmp->transfer_dma);
         usb_free_urb(tmp);
     }
 
     return urb;
 }
 
 /**
  * es58x_submit_urb() - Send data to the device.
  * @es58x_dev: ES58X device.
  * @urb: URB to be sent.
  * @netdev: CAN network device.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_submit_urb(struct es58x_device *es58x_dev, struct urb *urb,
                 struct net_device *netdev)
 {
     int ret;
 
     es58x_set_crc(urb->transfer_buffer, urb->transfer_buffer_length);
     urb->context = netdev;
     usb_anchor_urb(urb, &es58x_dev->tx_urbs_busy);
     ret = usb_submit_urb(urb, GFP_ATOMIC);
     if (ret) {
         netdev_err(netdev, "%s: USB send urb failure: %pe\n",
                __func__, ERR_PTR(ret));
         usb_unanchor_urb(urb);
         usb_free_coherent(urb->dev,
                   es58x_dev->param->tx_urb_cmd_max_len,
                   urb->transfer_buffer, urb->transfer_dma);
     }
     usb_free_urb(urb);
 
     return ret;
 }
 
 /**
  * es58x_send_msg() - Prepare an URB and submit it.
  * @es58x_dev: ES58X device.
  * @cmd_type: Command type.
  * @cmd_id: Command ID.
  * @msg: ES58X message to be sent.
  * @msg_len: Length of @msg.
  * @channel_idx: Index of the network device.
  *
  * Creates an URB command from a given message, sets the header and the
  * CRC and then submits it.
  *
  * Return: zero on success, errno when any error occurs.
  */
 int es58x_send_msg(struct es58x_device *es58x_dev, u8 cmd_type, u8 cmd_id,
            const void *msg, u16 msg_len, int channel_idx)
 {
     struct net_device *netdev;
     union es58x_urb_cmd *urb_cmd;
     struct urb *urb;
     int urb_cmd_len;
 
     if (channel_idx == ES58X_CHANNEL_IDX_NA)
         netdev = es58x_dev->netdev[0];  /* Default to first channel */
     else
         netdev = es58x_dev->netdev[channel_idx];
 
     urb_cmd_len = es58x_get_urb_cmd_len(es58x_dev, msg_len);
     if (urb_cmd_len > es58x_dev->param->tx_urb_cmd_max_len)
         return -EOVERFLOW;
 
     urb = es58x_get_tx_urb(es58x_dev);
     if (!urb)
         return -ENOMEM;
 
     urb_cmd = urb->transfer_buffer;
     es58x_dev->ops->fill_urb_header(urb_cmd, cmd_type, cmd_id,
                     channel_idx, msg_len);
     memcpy(&urb_cmd->raw_cmd[es58x_dev->param->urb_cmd_header_len],
            msg, msg_len);
     urb->transfer_buffer_length = urb_cmd_len;
 
     return es58x_submit_urb(es58x_dev, urb, netdev);
 }
 
 /**
  * es58x_alloc_rx_urbs() - Allocate RX URBs.
  * @es58x_dev: ES58X device.
  *
  * Allocate URBs for reception and anchor them.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_alloc_rx_urbs(struct es58x_device *es58x_dev)
 {
     const struct device *dev = es58x_dev->dev;
     const struct es58x_parameters *param = es58x_dev->param;
     u16 rx_buf_len = usb_maxpacket(es58x_dev->udev, es58x_dev->rx_pipe);
     struct urb *urb;
     u8 *buf;
     int i;
     int ret = -EINVAL;
 
     for (i = 0; i < param->rx_urb_max; i++) {
         ret = es58x_alloc_urb(es58x_dev, &urb, &buf, rx_buf_len,
                       GFP_KERNEL);
         if (ret)
             break;
 
         usb_fill_bulk_urb(urb, es58x_dev->udev, es58x_dev->rx_pipe,
                   buf, rx_buf_len, es58x_read_bulk_callback,
                   es58x_dev);
         usb_anchor_urb(urb, &es58x_dev->rx_urbs);
 
         ret = usb_submit_urb(urb, GFP_KERNEL);
         if (ret) {
             usb_unanchor_urb(urb);
             usb_free_coherent(es58x_dev->udev, rx_buf_len,
                       buf, urb->transfer_dma);
             usb_free_urb(urb);
             break;
         }
         usb_free_urb(urb);
     }
 
     if (i == 0) {
         dev_err(dev, "%s: Could not setup any rx URBs\n", __func__);
         return ret;
     }
     dev_dbg(dev, "%s: Allocated %d rx URBs each of size %u\n",
         __func__, i, rx_buf_len);
 
     return ret;
 }
 
 /**
  * es58x_free_urbs() - Free all the TX and RX URBs.
  * @es58x_dev: ES58X device.
  */
 static void es58x_free_urbs(struct es58x_device *es58x_dev)
 {
     struct urb *urb;
 
     if (!usb_wait_anchor_empty_timeout(&es58x_dev->tx_urbs_busy, 1000)) {
         dev_err(es58x_dev->dev, "%s: Timeout, some TX urbs still remain\n",
             __func__);
         usb_kill_anchored_urbs(&es58x_dev->tx_urbs_busy);
     }
 
     while ((urb = usb_get_from_anchor(&es58x_dev->tx_urbs_idle)) != NULL) {
         usb_free_coherent(urb->dev, es58x_dev->param->tx_urb_cmd_max_len,
                   urb->transfer_buffer, urb->transfer_dma);
         usb_free_urb(urb);
         atomic_dec(&es58x_dev->tx_urbs_idle_cnt);
     }
     if (atomic_read(&es58x_dev->tx_urbs_idle_cnt))
         dev_err(es58x_dev->dev,
             "All idle urbs were freed but tx_urb_idle_cnt is %d\n",
             atomic_read(&es58x_dev->tx_urbs_idle_cnt));
 
     usb_kill_anchored_urbs(&es58x_dev->rx_urbs);
 }
 
 /**
  * es58x_open() - Enable the network device.
  * @netdev: CAN network device.
  *
  * Called when the network transitions to the up state. Allocate the
  * URB resources if needed and open the channel.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_open(struct net_device *netdev)
 {
     struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
     int ret;
 
     if (!es58x_dev->opened_channel_cnt) {
         ret = es58x_alloc_rx_urbs(es58x_dev);
         if (ret)
             return ret;
 
         ret = es58x_set_realtime_diff_ns(es58x_dev);
         if (ret)
             goto free_urbs;
     }
 
     ret = open_candev(netdev);
     if (ret)
         goto free_urbs;
 
     ret = es58x_dev->ops->enable_channel(es58x_priv(netdev));
     if (ret)
         goto free_urbs;
 
     es58x_dev->opened_channel_cnt++;
     netif_start_queue(netdev);
 
     return ret;
 
  free_urbs:
     if (!es58x_dev->opened_channel_cnt)
         es58x_free_urbs(es58x_dev);
     netdev_err(netdev, "%s: Could not open the network device: %pe\n",
            __func__, ERR_PTR(ret));
 
     return ret;
 }
 
 /**
  * es58x_stop() - Disable the network device.
  * @netdev: CAN network device.
  *
  * Called when the network transitions to the down state. If all the
  * channels of the device are closed, free the URB resources which are
  * not needed anymore.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_stop(struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     struct es58x_device *es58x_dev = priv->es58x_dev;
     int ret;
 
     netif_stop_queue(netdev);
     ret = es58x_dev->ops->disable_channel(priv);
     if (ret)
         return ret;
 
     priv->can.state = CAN_STATE_STOPPED;
     es58x_can_reset_echo_fifo(netdev);
     close_candev(netdev);
 
     es58x_flush_pending_tx_msg(netdev);
 
     es58x_dev->opened_channel_cnt--;
     if (!es58x_dev->opened_channel_cnt)
         es58x_free_urbs(es58x_dev);
 
     return 0;
 }
 
 /**
  * es58x_xmit_commit() - Send the bulk urb.
  * @netdev: CAN network device.
  *
  * Do the bulk send. This function should be called only once by bulk
  * transmission.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_xmit_commit(struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     int ret;
 
     if (!es58x_is_can_state_active(netdev))
         return -ENETDOWN;
 
     if (es58x_is_echo_skb_threshold_reached(priv))
         netif_stop_queue(netdev);
 
     ret = es58x_submit_urb(priv->es58x_dev, priv->tx_urb, netdev);
     if (ret == 0)
         priv->tx_urb = NULL;
 
     return ret;
 }
 
 /**
  * es58x_xmit_more() - Can we put more packets?
  * @priv: ES58X private parameters related to the network device.
  *
  * Return: true if we can put more, false if it is time to send.
  */
 static bool es58x_xmit_more(struct es58x_priv *priv)
 {
     unsigned int free_slots =
         priv->can.echo_skb_max - (priv->tx_head - priv->tx_tail);
 
     return netdev_xmit_more() && free_slots > 0 &&
         priv->tx_can_msg_cnt < priv->es58x_dev->param->tx_bulk_max;
 }
 
 /**
  * es58x_start_xmit() - Transmit an skb.
  * @skb: socket buffer of a CAN message.
  * @netdev: CAN network device.
  *
  * Called when a packet needs to be transmitted.
  *
  * This function relies on Byte Queue Limits (BQL). The main benefit
  * is to increase the throughput by allowing bulk transfers
  * (c.f. xmit_more flag).
  *
  * Queues up to tx_bulk_max messages in &tx_urb buffer and does
  * a bulk send of all messages in one single URB.
  *
  * Return: NETDEV_TX_OK regardless of if we could transmit the @skb or
  *  had to drop it.
  */
 static netdev_tx_t es58x_start_xmit(struct sk_buff *skb,
                     struct net_device *netdev)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
     struct es58x_device *es58x_dev = priv->es58x_dev;
     unsigned int frame_len;
     int ret;
 
     if (can_dropped_invalid_skb(netdev, skb)) {
         if (priv->tx_urb)
             goto xmit_commit;
         return NETDEV_TX_OK;
     }
 
     if (priv->tx_urb && priv->tx_can_msg_is_fd != can_is_canfd_skb(skb)) {
         /* Can not do bulk send with mixed CAN and CAN FD frames. */
         ret = es58x_xmit_commit(netdev);
         if (ret)
             goto drop_skb;
     }
 
     if (!priv->tx_urb) {
         priv->tx_urb = es58x_get_tx_urb(es58x_dev);
         if (!priv->tx_urb) {
             ret = -ENOMEM;
             goto drop_skb;
         }
         priv->tx_can_msg_cnt = 0;
         priv->tx_can_msg_is_fd = can_is_canfd_skb(skb);
     }
 
     ret = es58x_dev->ops->tx_can_msg(priv, skb);
     if (ret)
         goto drop_skb;
 
     frame_len = can_skb_get_frame_len(skb);
     ret = can_put_echo_skb(skb, netdev,
                    priv->tx_head & es58x_dev->param->fifo_mask,
                    frame_len);
     if (ret)
         goto xmit_failure;
     netdev_sent_queue(netdev, frame_len);
 
     priv->tx_head++;
     priv->tx_can_msg_cnt++;
 
  xmit_commit:
     if (!es58x_xmit_more(priv)) {
         ret = es58x_xmit_commit(netdev);
         if (ret)
             goto xmit_failure;
     }
 
     return NETDEV_TX_OK;
 
  drop_skb:
     dev_kfree_skb(skb);
     netdev->stats.tx_dropped++;
  xmit_failure:
     netdev_warn(netdev, "%s: send message failure: %pe\n",
             __func__, ERR_PTR(ret));
     netdev->stats.tx_errors++;
     es58x_flush_pending_tx_msg(netdev);
     return NETDEV_TX_OK;
 }
 
 static const struct net_device_ops es58x_netdev_ops = {
     .ndo_open = es58x_open,
     .ndo_stop = es58x_stop,
     .ndo_start_xmit = es58x_start_xmit,
     .ndo_eth_ioctl = can_eth_ioctl_hwts,
 };
 
 static const struct ethtool_ops es58x_ethtool_ops = {
     .get_ts_info = can_ethtool_op_get_ts_info_hwts,
 };
 
 /**
  * es58x_set_mode() - Change network device mode.
  * @netdev: CAN network device.
  * @mode: either %CAN_MODE_START, %CAN_MODE_STOP or %CAN_MODE_SLEEP
  *
  * Currently, this function is only used to stop and restart the
  * channel during a bus off event (c.f. es58x_rx_err_msg() and
  * drivers/net/can/dev.c:can_restart() which are the two only
  * callers).
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_set_mode(struct net_device *netdev, enum can_mode mode)
 {
     struct es58x_priv *priv = es58x_priv(netdev);
 
     switch (mode) {
     case CAN_MODE_START:
         switch (priv->can.state) {
         case CAN_STATE_BUS_OFF:
             return priv->es58x_dev->ops->enable_channel(priv);
 
         case CAN_STATE_STOPPED:
             return es58x_open(netdev);
 
         case CAN_STATE_ERROR_ACTIVE:
         case CAN_STATE_ERROR_WARNING:
         case CAN_STATE_ERROR_PASSIVE:
         default:
             return 0;
         }
 
     case CAN_MODE_STOP:
         switch (priv->can.state) {
         case CAN_STATE_STOPPED:
             return 0;
 
         case CAN_STATE_ERROR_ACTIVE:
         case CAN_STATE_ERROR_WARNING:
         case CAN_STATE_ERROR_PASSIVE:
         case CAN_STATE_BUS_OFF:
         default:
             return priv->es58x_dev->ops->disable_channel(priv);
         }
 
     case CAN_MODE_SLEEP:
     default:
         return -EOPNOTSUPP;
     }
 }
 
 /**
  * es58x_init_priv() - Initialize private parameters.
  * @es58x_dev: ES58X device.
  * @priv: ES58X private parameters related to the network device.
  * @channel_idx: Index of the network device.
  */
 static void es58x_init_priv(struct es58x_device *es58x_dev,
                 struct es58x_priv *priv, int channel_idx)
 {
     const struct es58x_parameters *param = es58x_dev->param;
     struct can_priv *can = &priv->can;
 
     priv->es58x_dev = es58x_dev;
     priv->channel_idx = channel_idx;
     priv->tx_urb = NULL;
     priv->tx_can_msg_cnt = 0;
 
     can->bittiming_const = param->bittiming_const;
     if (param->ctrlmode_supported & CAN_CTRLMODE_FD) {
         can->data_bittiming_const = param->data_bittiming_const;
         can->tdc_const = param->tdc_const;
     }
     can->bitrate_max = param->bitrate_max;
     can->clock = param->clock;
     can->state = CAN_STATE_STOPPED;
     can->ctrlmode_supported = param->ctrlmode_supported;
     can->do_set_mode = es58x_set_mode;
 }
 
 /**
  * es58x_init_netdev() - Initialize the network device.
  * @es58x_dev: ES58X device.
  * @channel_idx: Index of the network device.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_init_netdev(struct es58x_device *es58x_dev, int channel_idx)
 {
     struct net_device *netdev;
     struct device *dev = es58x_dev->dev;
     int ret;
 
     netdev = alloc_candev(sizeof(struct es58x_priv),
                   es58x_dev->param->fifo_mask + 1);
     if (!netdev) {
         dev_err(dev, "Could not allocate candev\n");
         return -ENOMEM;
     }
     SET_NETDEV_DEV(netdev, dev);
     es58x_dev->netdev[channel_idx] = netdev;
     es58x_init_priv(es58x_dev, es58x_priv(netdev), channel_idx);
 
     netdev->netdev_ops = &es58x_netdev_ops;
     netdev->ethtool_ops = &es58x_ethtool_ops;
     netdev->flags |= IFF_ECHO;  /* We support local echo */
     netdev->dev_port = channel_idx;
 
     ret = register_candev(netdev);
     if (ret)
         return ret;
 
     netdev_queue_set_dql_min_limit(netdev_get_tx_queue(netdev, 0),
                        es58x_dev->param->dql_min_limit);
 
     return ret;
 }
 
 /**
  * es58x_free_netdevs() - Release all network resources of the device.
  * @es58x_dev: ES58X device.
  */
 static void es58x_free_netdevs(struct es58x_device *es58x_dev)
 {
     int i;
 
     for (i = 0; i < es58x_dev->num_can_ch; i++) {
         struct net_device *netdev = es58x_dev->netdev[i];
 
         if (!netdev)
             continue;
         unregister_candev(netdev);
         es58x_dev->netdev[i] = NULL;
         free_candev(netdev);
     }
 }
 
 /**
  * es58x_get_product_info() - Get the product information and print them.
  * @es58x_dev: ES58X device.
  *
  * Do a synchronous call to get the product information.
  *
  * Return: zero on success, errno when any error occurs.
  */
 static int es58x_get_product_info(struct es58x_device *es58x_dev)
 {
     struct usb_device *udev = es58x_dev->udev;
     const int es58x_prod_info_idx = 6;
     /* Empirical tests show a prod_info length of maximum 83,
      * below should be more than enough.
      */
     const size_t prod_info_len = 127;
     char *prod_info;
     int ret;
 
     prod_info = kmalloc(prod_info_len, GFP_KERNEL);
     if (!prod_info)
         return -ENOMEM;
 
     ret = usb_string(udev, es58x_prod_info_idx, prod_info, prod_info_len);
     if (ret < 0) {
         dev_err(es58x_dev->dev,
             "%s: Could not read the product info: %pe\n",
             __func__, ERR_PTR(ret));
         goto out_free;
     }
     if (ret >= prod_info_len - 1) {
         dev_warn(es58x_dev->dev,
              "%s: Buffer is too small, result might be truncated\n",
              __func__);
     }
     dev_info(es58x_dev->dev, "Product info: %s\n", prod_info);
 
  out_free:
     kfree(prod_info);
     return ret < 0 ? ret : 0;
 }
 
 /**
  * es58x_init_es58x_dev() - Initialize the ES58X device.
  * @intf: USB interface.
  * @driver_info: Quirks of the device.
  *
  * Return: pointer to an ES58X device on success, error pointer when
  *  any error occurs.
  */
 static struct es58x_device *es58x_init_es58x_dev(struct usb_interface *intf,
                          kernel_ulong_t driver_info)
 {
     struct device *dev = &intf->dev;
     struct es58x_device *es58x_dev;
     const struct es58x_parameters *param;
     const struct es58x_operators *ops;
     struct usb_device *udev = interface_to_usbdev(intf);
     struct usb_endpoint_descriptor *ep_in, *ep_out;
     int ret;
 
     dev_info(dev, "Starting %s %s (Serial Number %s)\n",
          udev->manufacturer, udev->product, udev->serial);
 
     ret = usb_find_common_endpoints(intf->cur_altsetting, &ep_in, &ep_out,
                     NULL, NULL);
     if (ret)
         return ERR_PTR(ret);
 
     if (driver_info & ES58X_FD_FAMILY) {
         param = &es58x_fd_param;
         ops = &es58x_fd_ops;
     } else {
         param = &es581_4_param;
         ops = &es581_4_ops;
     }
 
     es58x_dev = devm_kzalloc(dev, es58x_sizeof_es58x_device(param),
                  GFP_KERNEL);
     if (!es58x_dev)
         return ERR_PTR(-ENOMEM);
 
     es58x_dev->param = param;
     es58x_dev->ops = ops;
     es58x_dev->dev = dev;
     es58x_dev->udev = udev;
 
     if (driver_info & ES58X_DUAL_CHANNEL)
         es58x_dev->num_can_ch = 2;
     else
         es58x_dev->num_can_ch = 1;
 
     init_usb_anchor(&es58x_dev->rx_urbs);
     init_usb_anchor(&es58x_dev->tx_urbs_idle);
     init_usb_anchor(&es58x_dev->tx_urbs_busy);
     atomic_set(&es58x_dev->tx_urbs_idle_cnt, 0);
     usb_set_intfdata(intf, es58x_dev);
 
     es58x_dev->rx_pipe = usb_rcvbulkpipe(es58x_dev->udev,
                          ep_in->bEndpointAddress);
     es58x_dev->tx_pipe = usb_sndbulkpipe(es58x_dev->udev,
                          ep_out->bEndpointAddress);
 
     return es58x_dev;
 }
 
 /**
  * es58x_probe() - Initialize the USB device.
  * @intf: USB interface.
  * @id: USB device ID.
  *
  * Return: zero on success, -ENODEV if the interface is not supported
  * or errno when any other error occurs.
  */
 static int es58x_probe(struct usb_interface *intf,
                const struct usb_device_id *id)
 {
     struct es58x_device *es58x_dev;
     int ch_idx, ret;
 
     es58x_dev = es58x_init_es58x_dev(intf, id->driver_info);
     if (IS_ERR(es58x_dev))
         return PTR_ERR(es58x_dev);
 
     ret = es58x_get_product_info(es58x_dev);
     if (ret)
         return ret;
 
     for (ch_idx = 0; ch_idx < es58x_dev->num_can_ch; ch_idx++) {
         ret = es58x_init_netdev(es58x_dev, ch_idx);
         if (ret) {
             es58x_free_netdevs(es58x_dev);
             return ret;
         }
     }
 
     return ret;
 }
 
 /**
  * es58x_disconnect() - Disconnect the USB device.
  * @intf: USB interface
  *
  * Called by the usb core when driver is unloaded or device is
  * removed.
  */
 static void es58x_disconnect(struct usb_interface *intf)
 {
     struct es58x_device *es58x_dev = usb_get_intfdata(intf);
 
     dev_info(&intf->dev, "Disconnecting %s %s\n",
          es58x_dev->udev->manufacturer, es58x_dev->udev->product);
 
     es58x_free_netdevs(es58x_dev);
     es58x_free_urbs(es58x_dev);
     usb_set_intfdata(intf, NULL);
 }
 
 static struct usb_driver es58x_driver = {
     .name = KBUILD_MODNAME,
     .probe = es58x_probe,
     .disconnect = es58x_disconnect,
     .id_table = es58x_id_table
 };
 
 module_usb_driver(es58x_driver);

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