/*
 * CAN driver for PEAK System PCAN-USB FD / PCAN-USB Pro FD adapter
 *
 * Copyright (C) 2013-2014 Stephane Grosjean <s.grosjean@peak-system.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published
 * by the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#include <linux/netdevice.h>
#include <linux/usb.h>
#include <linux/module.h>

#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>

#include "pcan_usb_core.h"
#include "pcan_usb_pro.h"
#include "pcan_ucan.h"

MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB FD adapter");
MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB Pro FD adapter");

#define PCAN_USBPROFD_CHANNEL_COUNT     2
#define PCAN_USBFD_CHANNEL_COUNT        1

/* PCAN-USB Pro FD adapter internal clock (Hz) */
#define PCAN_UFD_CRYSTAL_HZ             80000000

#define PCAN_UFD_CMD_BUFFER_SIZE        512
#define PCAN_UFD_LOSPD_PKT_SIZE         64

/* PCAN-USB Pro FD command timeout (ms.) */
#define PCAN_UFD_CMD_TIMEOUT_MS         1000

/* PCAN-USB Pro FD rx/tx buffers size */
#define PCAN_UFD_RX_BUFFER_SIZE         2048
#define PCAN_UFD_TX_BUFFER_SIZE         512

/* read some versions info from the hw devcie */
struct __packed pcan_ufd_fw_info {
        __le16  size_of;        /* sizeof this */
        __le16  type;           /* type of this structure */
        u8      hw_type;        /* Type of hardware (HW_TYPE_xxx) */
        u8      bl_version[3];  /* Bootloader version */
        u8      hw_version;     /* Hardware version (PCB) */
        u8      fw_version[3];  /* Firmware version */
        __le32  dev_id[2];      /* "device id" per CAN */
        __le32  ser_no;         /* S/N */
        __le32  flags;          /* special functions */
};

/* handle device specific info used by the netdevices */
struct pcan_usb_fd_if {
        struct peak_usb_device  *dev[PCAN_USB_MAX_CHANNEL];
        struct pcan_ufd_fw_info fw_info;
        struct peak_time_ref    time_ref;
        int                     cm_ignore_count;
        int                     dev_opened_count;
};

/* device information */
struct pcan_usb_fd_device {
        struct peak_usb_device  dev;
        struct can_berr_counter bec;
        struct pcan_usb_fd_if   *usb_if;
        u8                      *cmd_buffer_addr;
};

/* Extended USB commands (non uCAN commands) */

/* Clock Modes command */
#define PCAN_UFD_CMD_CLK_SET            0x80

#define PCAN_UFD_CLK_80MHZ              0x0
#define PCAN_UFD_CLK_60MHZ              0x1
#define PCAN_UFD_CLK_40MHZ              0x2
#define PCAN_UFD_CLK_30MHZ              0x3
#define PCAN_UFD_CLK_24MHZ              0x4
#define PCAN_UFD_CLK_20MHZ              0x5
#define PCAN_UFD_CLK_DEF                PCAN_UFD_CLK_80MHZ

struct __packed pcan_ufd_clock {
        __le16  opcode_channel;

        u8      mode;
        u8      unused[5];
};

/* LED control command */
#define PCAN_UFD_CMD_LED_SET            0x86

#define PCAN_UFD_LED_DEV                0x00
#define PCAN_UFD_LED_FAST               0x01
#define PCAN_UFD_LED_SLOW               0x02
#define PCAN_UFD_LED_ON                 0x03
#define PCAN_UFD_LED_OFF                0x04
#define PCAN_UFD_LED_DEF                PCAN_UFD_LED_DEV

struct __packed pcan_ufd_led {
        __le16  opcode_channel;

        u8      mode;
        u8      unused[5];
};

/* Extended usage of uCAN commands CMD_xxx_xx_OPTION for PCAN-USB Pro FD */
#define PCAN_UFD_FLTEXT_CALIBRATION     0x8000

struct __packed pcan_ufd_options {
        __le16  opcode_channel;

        __le16  ucan_mask;
        u16     unused;
        __le16  usb_mask;
};

/* Extended usage of uCAN messages for PCAN-USB Pro FD */
#define PCAN_UFD_MSG_CALIBRATION        0x100

struct __packed pcan_ufd_ts_msg {
        __le16  size;
        __le16  type;
        __le32  ts_low;
        __le32  ts_high;
        __le16  usb_frame_index;
        u16     unused;
};

#define PCAN_UFD_MSG_OVERRUN            0x101

#define PCAN_UFD_OVMSG_CHANNEL(o)       ((o)->channel & 0xf)

struct __packed pcan_ufd_ovr_msg {
        __le16  size;
        __le16  type;
        __le32  ts_low;
        __le32  ts_high;
        u8      channel;
        u8      unused[3];
};

static inline int pufd_omsg_get_channel(struct pcan_ufd_ovr_msg *om)
{
        return om->channel & 0xf;
}

/* Clock mode frequency values */
static const u32 pcan_usb_fd_clk_freq[6] = {
        [PCAN_UFD_CLK_80MHZ] = 80000000,
        [PCAN_UFD_CLK_60MHZ] = 60000000,
        [PCAN_UFD_CLK_40MHZ] = 40000000,
        [PCAN_UFD_CLK_30MHZ] = 30000000,
        [PCAN_UFD_CLK_24MHZ] = 24000000,
        [PCAN_UFD_CLK_20MHZ] = 20000000
};

/* return a device USB interface */
static inline
struct pcan_usb_fd_if *pcan_usb_fd_dev_if(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);
        return pdev->usb_if;
}

/* return a device USB commands buffer */
static inline void *pcan_usb_fd_cmd_buffer(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);
        return pdev->cmd_buffer_addr;
}

/* send PCAN-USB Pro FD commands synchronously */
static int pcan_usb_fd_send_cmd(struct peak_usb_device *dev, void *cmd_tail)
{
        void *cmd_head = pcan_usb_fd_cmd_buffer(dev);
        int err = 0;
        u8 *packet_ptr;
        int i, n = 1, packet_len;
        ptrdiff_t cmd_len;

        /* usb device unregistered? */
        if (!(dev->state & PCAN_USB_STATE_CONNECTED))
                return 0;

        /* if a packet is not filled completely by commands, the command list
         * is terminated with an "end of collection" record.
         */
        cmd_len = cmd_tail - cmd_head;
        if (cmd_len <= (PCAN_UFD_CMD_BUFFER_SIZE - sizeof(u64))) {
                memset(cmd_tail, 0xff, sizeof(u64));
                cmd_len += sizeof(u64);
        }

        packet_ptr = cmd_head;

        /* firmware is not able to re-assemble 512 bytes buffer in full-speed */
        if ((dev->udev->speed != USB_SPEED_HIGH) &&
            (cmd_len > PCAN_UFD_LOSPD_PKT_SIZE)) {
                packet_len = PCAN_UFD_LOSPD_PKT_SIZE;
                n += cmd_len / packet_len;
        } else {
                packet_len = cmd_len;
        }

        for (i = 0; i < n; i++) {
                err = usb_bulk_msg(dev->udev,
                                   usb_sndbulkpipe(dev->udev,
                                                   PCAN_USBPRO_EP_CMDOUT),
                                   packet_ptr, packet_len,
                                   NULL, PCAN_UFD_CMD_TIMEOUT_MS);
                if (err) {
                        netdev_err(dev->netdev,
                                   "sending command failure: %d\n", err);
                        break;
                }

                packet_ptr += packet_len;
        }

        return err;
}

/* build the commands list in the given buffer, to enter operational mode */
static int pcan_usb_fd_build_restart_cmd(struct peak_usb_device *dev, u8 *buf)
{
        struct pucan_wr_err_cnt *prc;
        struct pucan_command *cmd;
        u8 *pc = buf;

        /* 1st, reset error counters: */
        prc = (struct pucan_wr_err_cnt *)pc;
        prc->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                       PUCAN_CMD_WR_ERR_CNT);

        /* select both counters */
        prc->sel_mask = cpu_to_le16(PUCAN_WRERRCNT_TE|PUCAN_WRERRCNT_RE);

        /* and reset their values */
        prc->tx_counter = 0;
        prc->rx_counter = 0;

        /* moves the pointer forward */
        pc += sizeof(struct pucan_wr_err_cnt);

        /* add command to switch from ISO to non-ISO mode, if fw allows it */
        if (dev->can.ctrlmode_supported & CAN_CTRLMODE_FD_NON_ISO) {
                struct pucan_options *puo = (struct pucan_options *)pc;

                puo->opcode_channel =
                        (dev->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO) ?
                        pucan_cmd_opcode_channel(dev,
                                                 PUCAN_CMD_CLR_DIS_OPTION) :
                        pucan_cmd_opcode_channel(dev, PUCAN_CMD_SET_EN_OPTION);

                puo->options = cpu_to_le16(PUCAN_OPTION_CANDFDISO);

                /* to be sure that no other extended bits will be taken into
                 * account
                 */
                puo->unused = 0;

                /* moves the pointer forward */
                pc += sizeof(struct pucan_options);
        }

        /* next, go back to operational mode */
        cmd = (struct pucan_command *)pc;
        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                (dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) ?
                                                PUCAN_CMD_LISTEN_ONLY_MODE :
                                                PUCAN_CMD_NORMAL_MODE);
        pc += sizeof(struct pucan_command);

        return pc - buf;
}

/* set CAN bus on/off */
static int pcan_usb_fd_set_bus(struct peak_usb_device *dev, u8 onoff)
{
        u8 *pc = pcan_usb_fd_cmd_buffer(dev);
        int l;

        if (onoff) {
                /* build the cmds list to enter operational mode */
                l = pcan_usb_fd_build_restart_cmd(dev, pc);
        } else {
                struct pucan_command *cmd = (struct pucan_command *)pc;

                /* build cmd to go back to reset mode */
                cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                        PUCAN_CMD_RESET_MODE);
                l = sizeof(struct pucan_command);
        }

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, pc + l);
}

/* set filtering masks:
 *
 *      idx  in range [0..63] selects a row #idx, all rows otherwise
 *      mask in range [0..0xffffffff] defines up to 32 CANIDs in the row(s)
 *
 *      Each bit of this 64 x 32 bits array defines a CANID value:
 *
 *      bit[i,j] = 1 implies that CANID=(i x 32)+j will be received, while
 *      bit[i,j] = 0 implies that CANID=(i x 32)+j will be discarded.
 */
static int pcan_usb_fd_set_filter_std(struct peak_usb_device *dev, int idx,
                                      u32 mask)
{
        struct pucan_filter_std *cmd = pcan_usb_fd_cmd_buffer(dev);
        int i, n;

        /* select all rows when idx is out of range [0..63] */
        if ((idx < 0) || (idx >= (1 << PUCAN_FLTSTD_ROW_IDX_BITS))) {
                n = 1 << PUCAN_FLTSTD_ROW_IDX_BITS;
                idx = 0;

        /* select the row (and only the row) otherwise */
        } else {
                n = idx + 1;
        }

        for (i = idx; i < n; i++, cmd++) {
                cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                        PUCAN_CMD_FILTER_STD);
                cmd->idx = cpu_to_le16(i);
                cmd->mask = cpu_to_le32(mask);
        }

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, cmd);
}

/* set/unset options
 *
 *      onoff   set(1)/unset(0) options
 *      mask    each bit defines a kind of options to set/unset
 */
static int pcan_usb_fd_set_options(struct peak_usb_device *dev,
                                   bool onoff, u16 ucan_mask, u16 usb_mask)
{
        struct pcan_ufd_options *cmd = pcan_usb_fd_cmd_buffer(dev);

        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                        (onoff) ? PUCAN_CMD_SET_EN_OPTION :
                                                  PUCAN_CMD_CLR_DIS_OPTION);

        cmd->ucan_mask = cpu_to_le16(ucan_mask);
        cmd->usb_mask = cpu_to_le16(usb_mask);

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, ++cmd);
}

/* setup LED control */
static int pcan_usb_fd_set_can_led(struct peak_usb_device *dev, u8 led_mode)
{
        struct pcan_ufd_led *cmd = pcan_usb_fd_cmd_buffer(dev);

        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                       PCAN_UFD_CMD_LED_SET);
        cmd->mode = led_mode;

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, ++cmd);
}

/* set CAN clock domain */
static int pcan_usb_fd_set_clock_domain(struct peak_usb_device *dev,
                                        u8 clk_mode)
{
        struct pcan_ufd_clock *cmd = pcan_usb_fd_cmd_buffer(dev);

        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                       PCAN_UFD_CMD_CLK_SET);
        cmd->mode = clk_mode;

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, ++cmd);
}

/* set bittiming for CAN and CAN-FD header */
static int pcan_usb_fd_set_bittiming_slow(struct peak_usb_device *dev,
                                          struct can_bittiming *bt)
{
        struct pucan_timing_slow *cmd = pcan_usb_fd_cmd_buffer(dev);

        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                       PUCAN_CMD_TIMING_SLOW);
        cmd->sjw_t = PUCAN_TSLOW_SJW_T(bt->sjw - 1,
                                dev->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES);

        cmd->tseg2 = PUCAN_TSLOW_TSEG2(bt->phase_seg2 - 1);
        cmd->tseg1 = PUCAN_TSLOW_TSEG1(bt->prop_seg + bt->phase_seg1 - 1);
        cmd->brp = cpu_to_le16(PUCAN_TSLOW_BRP(bt->brp - 1));

        cmd->ewl = 96;  /* default */

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, ++cmd);
}

/* set CAN-FD bittiming for data */
static int pcan_usb_fd_set_bittiming_fast(struct peak_usb_device *dev,
                                          struct can_bittiming *bt)
{
        struct pucan_timing_fast *cmd = pcan_usb_fd_cmd_buffer(dev);

        cmd->opcode_channel = pucan_cmd_opcode_channel(dev,
                                                       PUCAN_CMD_TIMING_FAST);
        cmd->sjw = PUCAN_TFAST_SJW(bt->sjw - 1);
        cmd->tseg2 = PUCAN_TFAST_TSEG2(bt->phase_seg2 - 1);
        cmd->tseg1 = PUCAN_TFAST_TSEG1(bt->prop_seg + bt->phase_seg1 - 1);
        cmd->brp = cpu_to_le16(PUCAN_TFAST_BRP(bt->brp - 1));

        /* send the command */
        return pcan_usb_fd_send_cmd(dev, ++cmd);
}

/* handle restart but in asynchronously way
 * (uses PCAN-USB Pro code to complete asynchronous request)
 */
static int pcan_usb_fd_restart_async(struct peak_usb_device *dev,
                                     struct urb *urb, u8 *buf)
{
        u8 *pc = buf;

        /* build the entire cmds list in the provided buffer, to go back into
         * operational mode.
         */
        pc += pcan_usb_fd_build_restart_cmd(dev, pc);

        /* add EOC */
        memset(pc, 0xff, sizeof(struct pucan_command));
        pc += sizeof(struct pucan_command);

        /* complete the URB */
        usb_fill_bulk_urb(urb, dev->udev,
                          usb_sndbulkpipe(dev->udev, PCAN_USBPRO_EP_CMDOUT),
                          buf, pc - buf,
                          pcan_usb_pro_restart_complete, dev);

        /* and submit it. */
        return usb_submit_urb(urb, GFP_ATOMIC);
}

static int pcan_usb_fd_drv_loaded(struct peak_usb_device *dev, bool loaded)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

        pdev->cmd_buffer_addr[0] = 0;
        pdev->cmd_buffer_addr[1] = !!loaded;

        return pcan_usb_pro_send_req(dev,
                                PCAN_USBPRO_REQ_FCT,
                                PCAN_USBPRO_FCT_DRVLD,
                                pdev->cmd_buffer_addr,
                                PCAN_USBPRO_FCT_DRVLD_REQ_LEN);
}

static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
                                     struct pucan_msg *rx_msg)
{
        struct pucan_rx_msg *rm = (struct pucan_rx_msg *)rx_msg;
        struct peak_usb_device *dev = usb_if->dev[pucan_msg_get_channel(rm)];
        struct net_device *netdev = dev->netdev;
        struct canfd_frame *cfd;
        struct sk_buff *skb;
        const u16 rx_msg_flags = le16_to_cpu(rm->flags);

        if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN) {
                /* CANFD frame case */
                skb = alloc_canfd_skb(netdev, &cfd);
                if (!skb)
                        return -ENOMEM;

                if (rx_msg_flags & PUCAN_MSG_BITRATE_SWITCH)
                        cfd->flags |= CANFD_BRS;

                if (rx_msg_flags & PUCAN_MSG_ERROR_STATE_IND)
                        cfd->flags |= CANFD_ESI;

                cfd->len = can_dlc2len(get_canfd_dlc(pucan_msg_get_dlc(rm)));
        } else {
                /* CAN 2.0 frame case */
                skb = alloc_can_skb(netdev, (struct can_frame **)&cfd);
                if (!skb)
                        return -ENOMEM;

                cfd->len = get_can_dlc(pucan_msg_get_dlc(rm));
        }

        cfd->can_id = le32_to_cpu(rm->can_id);

        if (rx_msg_flags & PUCAN_MSG_EXT_ID)
                cfd->can_id |= CAN_EFF_FLAG;

        if (rx_msg_flags & PUCAN_MSG_RTR)
                cfd->can_id |= CAN_RTR_FLAG;
        else
                memcpy(cfd->data, rm->d, cfd->len);

        peak_usb_netif_rx(skb, &usb_if->time_ref,
                          le32_to_cpu(rm->ts_low), le32_to_cpu(rm->ts_high));

        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += cfd->len;

        return 0;
}

/* handle uCAN status message */
static int pcan_usb_fd_decode_status(struct pcan_usb_fd_if *usb_if,
                                     struct pucan_msg *rx_msg)
{
        struct pucan_status_msg *sm = (struct pucan_status_msg *)rx_msg;
        struct peak_usb_device *dev = usb_if->dev[pucan_stmsg_get_channel(sm)];
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);
        enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
        enum can_state rx_state, tx_state;
        struct net_device *netdev = dev->netdev;
        struct can_frame *cf;
        struct sk_buff *skb;

        /* nothing should be sent while in BUS_OFF state */
        if (dev->can.state == CAN_STATE_BUS_OFF)
                return 0;

        if (sm->channel_p_w_b & PUCAN_BUS_BUSOFF) {
                new_state = CAN_STATE_BUS_OFF;
        } else if (sm->channel_p_w_b & PUCAN_BUS_PASSIVE) {
                new_state = CAN_STATE_ERROR_PASSIVE;
        } else if (sm->channel_p_w_b & PUCAN_BUS_WARNING) {
                new_state = CAN_STATE_ERROR_WARNING;
        } else {
                /* no error bit (so, no error skb, back to active state) */
                dev->can.state = CAN_STATE_ERROR_ACTIVE;
                pdev->bec.txerr = 0;
                pdev->bec.rxerr = 0;
                return 0;
        }

        /* state hasn't changed */
        if (new_state == dev->can.state)
                return 0;

        /* handle bus state change */
        tx_state = (pdev->bec.txerr >= pdev->bec.rxerr) ? new_state : 0;
        rx_state = (pdev->bec.txerr <= pdev->bec.rxerr) ? new_state : 0;

        /* allocate an skb to store the error frame */
        skb = alloc_can_err_skb(netdev, &cf);
        if (skb)
                can_change_state(netdev, cf, tx_state, rx_state);

        /* things must be done even in case of OOM */
        if (new_state == CAN_STATE_BUS_OFF)
                can_bus_off(netdev);

        if (!skb)
                return -ENOMEM;

        peak_usb_netif_rx(skb, &usb_if->time_ref,
                          le32_to_cpu(sm->ts_low), le32_to_cpu(sm->ts_high));

        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += cf->can_dlc;

        return 0;
}

/* handle uCAN error message */
static int pcan_usb_fd_decode_error(struct pcan_usb_fd_if *usb_if,
                                    struct pucan_msg *rx_msg)
{
        struct pucan_error_msg *er = (struct pucan_error_msg *)rx_msg;
        struct peak_usb_device *dev = usb_if->dev[pucan_ermsg_get_channel(er)];
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

        /* keep a trace of tx and rx error counters for later use */
        pdev->bec.txerr = er->tx_err_cnt;
        pdev->bec.rxerr = er->rx_err_cnt;

        return 0;
}

/* handle uCAN overrun message */
static int pcan_usb_fd_decode_overrun(struct pcan_usb_fd_if *usb_if,
                                      struct pucan_msg *rx_msg)
{
        struct pcan_ufd_ovr_msg *ov = (struct pcan_ufd_ovr_msg *)rx_msg;
        struct peak_usb_device *dev = usb_if->dev[pufd_omsg_get_channel(ov)];
        struct net_device *netdev = dev->netdev;
        struct can_frame *cf;
        struct sk_buff *skb;

        /* allocate an skb to store the error frame */
        skb = alloc_can_err_skb(netdev, &cf);
        if (!skb)
                return -ENOMEM;

        cf->can_id |= CAN_ERR_CRTL;
        cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;

        peak_usb_netif_rx(skb, &usb_if->time_ref,
                          le32_to_cpu(ov->ts_low), le32_to_cpu(ov->ts_high));

        netdev->stats.rx_over_errors++;
        netdev->stats.rx_errors++;

        return 0;
}

/* handle USB calibration message */
static void pcan_usb_fd_decode_ts(struct pcan_usb_fd_if *usb_if,
                                  struct pucan_msg *rx_msg)
{
        struct pcan_ufd_ts_msg *ts = (struct pcan_ufd_ts_msg *)rx_msg;

        /* should wait until clock is stabilized */
        if (usb_if->cm_ignore_count > 0)
                usb_if->cm_ignore_count--;
        else
                peak_usb_set_ts_now(&usb_if->time_ref, le32_to_cpu(ts->ts_low));
}

/* callback for bulk IN urb */
static int pcan_usb_fd_decode_buf(struct peak_usb_device *dev, struct urb *urb)
{
        struct pcan_usb_fd_if *usb_if = pcan_usb_fd_dev_if(dev);
        struct net_device *netdev = dev->netdev;
        struct pucan_msg *rx_msg;
        u8 *msg_ptr, *msg_end;
        int err = 0;

        /* loop reading all the records from the incoming message */
        msg_ptr = urb->transfer_buffer;
        msg_end = urb->transfer_buffer + urb->actual_length;
        for (; msg_ptr < msg_end;) {
                u16 rx_msg_type, rx_msg_size;

                rx_msg = (struct pucan_msg *)msg_ptr;
                if (!rx_msg->size) {
                        /* null packet found: end of list */
                        break;
                }

                rx_msg_size = le16_to_cpu(rx_msg->size);
                rx_msg_type = le16_to_cpu(rx_msg->type);

                /* check if the record goes out of current packet */
                if (msg_ptr + rx_msg_size > msg_end) {
                        netdev_err(netdev,
                                   "got frag rec: should inc usb rx buf sze\n");
                        err = -EBADMSG;
                        break;
                }

                switch (rx_msg_type) {
                case PUCAN_MSG_CAN_RX:
                        err = pcan_usb_fd_decode_canmsg(usb_if, rx_msg);
                        if (err < 0)
                                goto fail;
                        break;

                case PCAN_UFD_MSG_CALIBRATION:
                        pcan_usb_fd_decode_ts(usb_if, rx_msg);
                        break;

                case PUCAN_MSG_ERROR:
                        err = pcan_usb_fd_decode_error(usb_if, rx_msg);
                        if (err < 0)
                                goto fail;
                        break;

                case PUCAN_MSG_STATUS:
                        err = pcan_usb_fd_decode_status(usb_if, rx_msg);
                        if (err < 0)
                                goto fail;
                        break;

                case PCAN_UFD_MSG_OVERRUN:
                        err = pcan_usb_fd_decode_overrun(usb_if, rx_msg);
                        if (err < 0)
                                goto fail;
                        break;

                default:
                        netdev_err(netdev,
                                   "unhandled msg type 0x%02x (%d): ignored\n",
                                   rx_msg_type, rx_msg_type);
                        break;
                }

                msg_ptr += rx_msg_size;
        }

fail:
        if (err)
                pcan_dump_mem("received msg",
                              urb->transfer_buffer, urb->actual_length);
        return err;
}

/* CAN/CANFD frames encoding callback */
static int pcan_usb_fd_encode_msg(struct peak_usb_device *dev,
                                  struct sk_buff *skb, u8 *obuf, size_t *size)
{
        struct pucan_tx_msg *tx_msg = (struct pucan_tx_msg *)obuf;
        struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
        u16 tx_msg_size, tx_msg_flags;
        u8 can_dlc;

        tx_msg_size = ALIGN(sizeof(struct pucan_tx_msg) + cfd->len, 4);
        tx_msg->size = cpu_to_le16(tx_msg_size);
        tx_msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);

        tx_msg_flags = 0;
        if (cfd->can_id & CAN_EFF_FLAG) {
                tx_msg_flags |= PUCAN_MSG_EXT_ID;
                tx_msg->can_id = cpu_to_le32(cfd->can_id & CAN_EFF_MASK);
        } else {
                tx_msg->can_id = cpu_to_le32(cfd->can_id & CAN_SFF_MASK);
        }

        if (can_is_canfd_skb(skb)) {
                /* considering a CANFD frame */
                can_dlc = can_len2dlc(cfd->len);

                tx_msg_flags |= PUCAN_MSG_EXT_DATA_LEN;

                if (cfd->flags & CANFD_BRS)
                        tx_msg_flags |= PUCAN_MSG_BITRATE_SWITCH;

                if (cfd->flags & CANFD_ESI)
                        tx_msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
        } else {
                /* CAND 2.0 frames */
                can_dlc = cfd->len;

                if (cfd->can_id & CAN_RTR_FLAG)
                        tx_msg_flags |= PUCAN_MSG_RTR;
        }

        tx_msg->flags = cpu_to_le16(tx_msg_flags);
        tx_msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(dev->ctrl_idx, can_dlc);
        memcpy(tx_msg->d, cfd->data, cfd->len);

        /* add null size message to tag the end (messages are 32-bits aligned)
         */
        tx_msg = (struct pucan_tx_msg *)(obuf + tx_msg_size);

        tx_msg->size = 0;

        /* set the whole size of the USB packet to send */
        *size = tx_msg_size + sizeof(u32);

        return 0;
}

/* start the interface (last chance before set bus on) */
static int pcan_usb_fd_start(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);
        int err;

        /* set filter mode: all acceptance */
        err = pcan_usb_fd_set_filter_std(dev, -1, 0xffffffff);
        if (err)
                return err;

        /* opening first device: */
        if (pdev->usb_if->dev_opened_count == 0) {
                /* reset time_ref */
                peak_usb_init_time_ref(&pdev->usb_if->time_ref,
                                       &pcan_usb_pro_fd);

                /* enable USB calibration messages */
                err = pcan_usb_fd_set_options(dev, 1,
                                              PUCAN_OPTION_ERROR,
                                              PCAN_UFD_FLTEXT_CALIBRATION);
        }

        pdev->usb_if->dev_opened_count++;

        /* reset cached error counters */
        pdev->bec.txerr = 0;
        pdev->bec.rxerr = 0;

        return err;
}

/* socket callback used to copy berr counters values receieved through USB */
static int pcan_usb_fd_get_berr_counter(const struct net_device *netdev,
                                        struct can_berr_counter *bec)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

        *bec = pdev->bec;

        /* must return 0 */
        return 0;
}

/* stop interface (last chance before set bus off) */
static int pcan_usb_fd_stop(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

        /* turn off special msgs for that interface if no other dev opened */
        if (pdev->usb_if->dev_opened_count == 1)
                pcan_usb_fd_set_options(dev, 0,
                                        PUCAN_OPTION_ERROR,
                                        PCAN_UFD_FLTEXT_CALIBRATION);
        pdev->usb_if->dev_opened_count--;

        return 0;
}

/* called when probing, to initialize a device object */
static int pcan_usb_fd_init(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);
        int i, err = -ENOMEM;

        /* do this for 1st channel only */
        if (!dev->prev_siblings) {
                /* allocate netdevices common structure attached to first one */
                pdev->usb_if = kzalloc(sizeof(*pdev->usb_if), GFP_KERNEL);
                if (!pdev->usb_if)
                        goto err_out;

                /* allocate command buffer once for all for the interface */
                pdev->cmd_buffer_addr = kmalloc(PCAN_UFD_CMD_BUFFER_SIZE,
                                                GFP_KERNEL);
                if (!pdev->cmd_buffer_addr)
                        goto err_out_1;

                /* number of ts msgs to ignore before taking one into account */
                pdev->usb_if->cm_ignore_count = 5;

                err = pcan_usb_pro_send_req(dev, PCAN_USBPRO_REQ_INFO,
                                            PCAN_USBPRO_INFO_FW,
                                            &pdev->usb_if->fw_info,
                                            sizeof(pdev->usb_if->fw_info));
                if (err) {
                        dev_err(dev->netdev->dev.parent,
                                "unable to read %s firmware info (err %d)\n",
                                dev->adapter->name, err);
                        goto err_out_2;
                }

                /* explicit use of dev_xxx() instead of netdev_xxx() here:
                 * information displayed are related to the device itself, not
                 * to the canx (channel) device.
                 */
                dev_info(dev->netdev->dev.parent,
                         "PEAK-System %s v%u fw v%u.%u.%u (%u channels)\n",
                         dev->adapter->name, pdev->usb_if->fw_info.hw_version,
                         pdev->usb_if->fw_info.fw_version[0],
                         pdev->usb_if->fw_info.fw_version[1],
                         pdev->usb_if->fw_info.fw_version[2],
                         dev->adapter->ctrl_count);

                /* check for ability to switch between ISO/non-ISO modes */
                if (pdev->usb_if->fw_info.fw_version[0] >= 2) {
                        /* firmware >= 2.x supports ISO/non-ISO switching */
                        dev->can.ctrlmode_supported |= CAN_CTRLMODE_FD_NON_ISO;
                } else {
                        /* firmware < 2.x only supports fixed(!) non-ISO */
                        dev->can.ctrlmode |= CAN_CTRLMODE_FD_NON_ISO;
                }

                /* tell the hardware the can driver is running */
                err = pcan_usb_fd_drv_loaded(dev, 1);
                if (err) {
                        dev_err(dev->netdev->dev.parent,
                                "unable to tell %s driver is loaded (err %d)\n",
                                dev->adapter->name, err);
                        goto err_out_2;
                }
        } else {
                /* otherwise, simply copy previous sibling's values */
                struct pcan_usb_fd_device *ppdev =
                        container_of(dev->prev_siblings,
                                     struct pcan_usb_fd_device, dev);

                pdev->usb_if = ppdev->usb_if;
                pdev->cmd_buffer_addr = ppdev->cmd_buffer_addr;

                /* do a copy of the ctrlmode[_supported] too */
                dev->can.ctrlmode = ppdev->dev.can.ctrlmode;
                dev->can.ctrlmode_supported = ppdev->dev.can.ctrlmode_supported;
        }

        pdev->usb_if->dev[dev->ctrl_idx] = dev;
        dev->device_number =
                le32_to_cpu(pdev->usb_if->fw_info.dev_id[dev->ctrl_idx]);

        /* set clock domain */
        for (i = 0; i < ARRAY_SIZE(pcan_usb_fd_clk_freq); i++)
                if (dev->adapter->clock.freq == pcan_usb_fd_clk_freq[i])
                        break;

        if (i >= ARRAY_SIZE(pcan_usb_fd_clk_freq)) {
                dev_warn(dev->netdev->dev.parent,
                         "incompatible clock frequencies\n");
                err = -EINVAL;
                goto err_out_2;
        }

        pcan_usb_fd_set_clock_domain(dev, i);

        /* set LED in default state (end of init phase) */
        pcan_usb_fd_set_can_led(dev, PCAN_UFD_LED_DEF);

        return 0;

err_out_2:
        kfree(pdev->cmd_buffer_addr);
err_out_1:
        kfree(pdev->usb_if);
err_out:
        return err;
}

/* called when driver module is being unloaded */
static void pcan_usb_fd_exit(struct peak_usb_device *dev)
{
        struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

        /* when rmmod called before unplug and if down, should reset things
         * before leaving
         */
        if (dev->can.state != CAN_STATE_STOPPED) {
                /* set bus off on the corresponding channel */
                pcan_usb_fd_set_bus(dev, 0);
        }

        /* switch off corresponding CAN LEDs */
        pcan_usb_fd_set_can_led(dev, PCAN_UFD_LED_OFF);

        /* if channel #0 (only) */
        if (dev->ctrl_idx == 0) {
                /* turn off calibration message if any device were opened */
                if (pdev->usb_if->dev_opened_count > 0)
                        pcan_usb_fd_set_options(dev, 0,
                                                PUCAN_OPTION_ERROR,
                                                PCAN_UFD_FLTEXT_CALIBRATION);

                /* tell USB adapter that the driver is being unloaded */
                pcan_usb_fd_drv_loaded(dev, 0);
        }
}

/* called when the USB adapter is unplugged */
static void pcan_usb_fd_free(struct peak_usb_device *dev)
{
        /* last device: can free shared objects now */
        if (!dev->prev_siblings && !dev->next_siblings) {
                struct pcan_usb_fd_device *pdev =
                        container_of(dev, struct pcan_usb_fd_device, dev);

                /* free commands buffer */
                kfree(pdev->cmd_buffer_addr);

                /* free usb interface object */
                kfree(pdev->usb_if);
        }
}

/* describes the PCAN-USB FD adapter */
const struct peak_usb_adapter pcan_usb_fd = {
        .name = "PCAN-USB FD",
        .device_id = PCAN_USBFD_PRODUCT_ID,
        .ctrl_count = PCAN_USBFD_CHANNEL_COUNT,
        .ctrlmode_supported = CAN_CTRLMODE_FD |
                        CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
        .clock = {
                .freq = PCAN_UFD_CRYSTAL_HZ,

        },
        .bittiming_const = {
                .name = "pcan_usb_fd",
                .tseg1_min = 1,
                .tseg1_max = 64,
                .tseg2_min = 1,
                .tseg2_max = 16,
                .sjw_max = 16,
                .brp_min = 1,
                .brp_max = 1024,
                .brp_inc = 1,
        },
        .data_bittiming_const = {
                .name = "pcan_usb_fd",
                .tseg1_min = 1,
                .tseg1_max = 16,
                .tseg2_min = 1,
                .tseg2_max = 8,
                .sjw_max = 4,
                .brp_min = 1,
                .brp_max = 1024,
                .brp_inc = 1,
        },

        /* size of device private data */
        .sizeof_dev_private = sizeof(struct pcan_usb_fd_device),

        /* timestamps usage */
        .ts_used_bits = 32,
        .ts_period = 1000000, /* calibration period in ts. */
        .us_per_ts_scale = 1, /* us = (ts * scale) >> shift */
        .us_per_ts_shift = 0,

        /* give here messages in/out endpoints */
        .ep_msg_in = PCAN_USBPRO_EP_MSGIN,
        .ep_msg_out = {PCAN_USBPRO_EP_MSGOUT_0},

        /* size of rx/tx usb buffers */
        .rx_buffer_size = PCAN_UFD_RX_BUFFER_SIZE,
        .tx_buffer_size = PCAN_UFD_TX_BUFFER_SIZE,

        /* device callbacks */
        .intf_probe = pcan_usb_pro_probe,       /* same as PCAN-USB Pro */
        .dev_init = pcan_usb_fd_init,

        .dev_exit = pcan_usb_fd_exit,
        .dev_free = pcan_usb_fd_free,
        .dev_set_bus = pcan_usb_fd_set_bus,
        .dev_set_bittiming = pcan_usb_fd_set_bittiming_slow,
        .dev_set_data_bittiming = pcan_usb_fd_set_bittiming_fast,
        .dev_decode_buf = pcan_usb_fd_decode_buf,
        .dev_start = pcan_usb_fd_start,
        .dev_stop = pcan_usb_fd_stop,
        .dev_restart_async = pcan_usb_fd_restart_async,
        .dev_encode_msg = pcan_usb_fd_encode_msg,

        .do_get_berr_counter = pcan_usb_fd_get_berr_counter,
};

/* describes the PCAN-USB Pro FD adapter */
const struct peak_usb_adapter pcan_usb_pro_fd = {
        .name = "PCAN-USB Pro FD",
        .device_id = PCAN_USBPROFD_PRODUCT_ID,
        .ctrl_count = PCAN_USBPROFD_CHANNEL_COUNT,
        .ctrlmode_supported = CAN_CTRLMODE_FD |
                        CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
        .clock = {
                .freq = PCAN_UFD_CRYSTAL_HZ,
        },
        .bittiming_const = {
                .name = "pcan_usb_pro_fd",
                .tseg1_min = 1,
                .tseg1_max = 64,
                .tseg2_min = 1,
                .tseg2_max = 16,
                .sjw_max = 16,
                .brp_min = 1,
                .brp_max = 1024,
                .brp_inc = 1,
        },
        .data_bittiming_const = {
                .name = "pcan_usb_pro_fd",
                .tseg1_min = 1,
                .tseg1_max = 16,
                .tseg2_min = 1,
                .tseg2_max = 8,
                .sjw_max = 4,
                .brp_min = 1,
                .brp_max = 1024,
                .brp_inc = 1,
        },

        /* size of device private data */
        .sizeof_dev_private = sizeof(struct pcan_usb_fd_device),

        /* timestamps usage */
        .ts_used_bits = 32,
        .ts_period = 1000000, /* calibration period in ts. */
        .us_per_ts_scale = 1, /* us = (ts * scale) >> shift */
        .us_per_ts_shift = 0,

        /* give here messages in/out endpoints */
        .ep_msg_in = PCAN_USBPRO_EP_MSGIN,
        .ep_msg_out = {PCAN_USBPRO_EP_MSGOUT_0, PCAN_USBPRO_EP_MSGOUT_1},

        /* size of rx/tx usb buffers */
        .rx_buffer_size = PCAN_UFD_RX_BUFFER_SIZE,
        .tx_buffer_size = PCAN_UFD_TX_BUFFER_SIZE,

        /* device callbacks */
        .intf_probe = pcan_usb_pro_probe,       /* same as PCAN-USB Pro */
        .dev_init = pcan_usb_fd_init,

        .dev_exit = pcan_usb_fd_exit,
        .dev_free = pcan_usb_fd_free,
        .dev_set_bus = pcan_usb_fd_set_bus,
        .dev_set_bittiming = pcan_usb_fd_set_bittiming_slow,
        .dev_set_data_bittiming = pcan_usb_fd_set_bittiming_fast,
        .dev_decode_buf = pcan_usb_fd_decode_buf,
        .dev_start = pcan_usb_fd_start,
        .dev_stop = pcan_usb_fd_stop,
        .dev_restart_async = pcan_usb_fd_restart_async,
        .dev_encode_msg = pcan_usb_fd_encode_msg,

        .do_get_berr_counter = pcan_usb_fd_get_berr_counter,
};