/*
 * Copyright (C) 2007, 2011 Wolfgang Grandegger <wg@grandegger.com>
 * Copyright (C) 2012 Stephane Grosjean <s.grosjean@peak-system.com>
 *
 * Copyright (C) 2016  PEAK System-Technik GmbH
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * 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/can.h>
#include <linux/can/dev.h>

#include "peak_canfd_user.h"

/* internal IP core cache size (used as default echo skbs max number) */
#define PCANFD_ECHO_SKB_MAX             24

/* bittiming ranges of the PEAK-System PC CAN-FD interfaces */
static const struct can_bittiming_const peak_canfd_nominal_const = {
        .name = "peak_canfd",
        .tseg1_min = 1,
        .tseg1_max = (1 << PUCAN_TSLOW_TSGEG1_BITS),
        .tseg2_min = 1,
        .tseg2_max = (1 << PUCAN_TSLOW_TSGEG2_BITS),
        .sjw_max = (1 << PUCAN_TSLOW_SJW_BITS),
        .brp_min = 1,
        .brp_max = (1 << PUCAN_TSLOW_BRP_BITS),
        .brp_inc = 1,
};

static const struct can_bittiming_const peak_canfd_data_const = {
        .name = "peak_canfd",
        .tseg1_min = 1,
        .tseg1_max = (1 << PUCAN_TFAST_TSGEG1_BITS),
        .tseg2_min = 1,
        .tseg2_max = (1 << PUCAN_TFAST_TSGEG2_BITS),
        .sjw_max = (1 << PUCAN_TFAST_SJW_BITS),
        .brp_min = 1,
        .brp_max = (1 << PUCAN_TFAST_BRP_BITS),
        .brp_inc = 1,
};

static struct peak_canfd_priv *pucan_init_cmd(struct peak_canfd_priv *priv)
{
        priv->cmd_len = 0;
        return priv;
}

static void *pucan_add_cmd(struct peak_canfd_priv *priv, int cmd_op)
{
        struct pucan_command *cmd;

        if (priv->cmd_len + sizeof(*cmd) > priv->cmd_maxlen)
                return NULL;

        cmd = priv->cmd_buffer + priv->cmd_len;

        /* reset all unused bit to default */
        memset(cmd, 0, sizeof(*cmd));

        cmd->opcode_channel = pucan_cmd_opcode_channel(priv->index, cmd_op);
        priv->cmd_len += sizeof(*cmd);

        return cmd;
}

static int pucan_write_cmd(struct peak_canfd_priv *priv)
{
        int err;

        if (priv->pre_cmd) {
                err = priv->pre_cmd(priv);
                if (err)
                        return err;
        }

        err = priv->write_cmd(priv);
        if (err)
                return err;

        if (priv->post_cmd)
                err = priv->post_cmd(priv);

        return err;
}

/* uCAN commands interface functions */
static int pucan_set_reset_mode(struct peak_canfd_priv *priv)
{
        pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RESET_MODE);
        return pucan_write_cmd(priv);
}

static int pucan_set_normal_mode(struct peak_canfd_priv *priv)
{
        int err;

        pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_NORMAL_MODE);
        err = pucan_write_cmd(priv);
        if (!err)
                priv->can.state = CAN_STATE_ERROR_ACTIVE;

        return err;
}

static int pucan_set_listen_only_mode(struct peak_canfd_priv *priv)
{
        int err;

        pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_LISTEN_ONLY_MODE);
        err = pucan_write_cmd(priv);
        if (!err)
                priv->can.state = CAN_STATE_ERROR_ACTIVE;

        return err;
}

static int pucan_set_timing_slow(struct peak_canfd_priv *priv,
                                 const struct can_bittiming *pbt)
{
        struct pucan_timing_slow *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_SLOW);

        cmd->sjw_t = PUCAN_TSLOW_SJW_T(pbt->sjw - 1,
                                priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES);
        cmd->tseg1 = PUCAN_TSLOW_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
        cmd->tseg2 = PUCAN_TSLOW_TSEG2(pbt->phase_seg2 - 1);
        cmd->brp = cpu_to_le16(PUCAN_TSLOW_BRP(pbt->brp - 1));

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

        netdev_dbg(priv->ndev,
                   "nominal: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
                   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw_t);

        return pucan_write_cmd(priv);
}

static int pucan_set_timing_fast(struct peak_canfd_priv *priv,
                                 const struct can_bittiming *pbt)
{
        struct pucan_timing_fast *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_FAST);

        cmd->sjw = PUCAN_TFAST_SJW(pbt->sjw - 1);
        cmd->tseg1 = PUCAN_TFAST_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
        cmd->tseg2 = PUCAN_TFAST_TSEG2(pbt->phase_seg2 - 1);
        cmd->brp = cpu_to_le16(PUCAN_TFAST_BRP(pbt->brp - 1));

        netdev_dbg(priv->ndev,
                   "data: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
                   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw);

        return pucan_write_cmd(priv);
}

static int pucan_set_std_filter(struct peak_canfd_priv *priv, u8 row, u32 mask)
{
        struct pucan_std_filter *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_STD_FILTER);

        /* all the 11-bits CAN ID values are represented by one bit in a
         * 64 rows array of 32 bits: the upper 6 bits of the CAN ID select the
         * row while the lowest 5 bits select the bit in that row.
         *
         * bit  filter
         * 1    passed
         * 0    discarded
         */

        /* select the row */
        cmd->idx = row;

        /* set/unset bits in the row */
        cmd->mask = cpu_to_le32(mask);

        return pucan_write_cmd(priv);
}

static int pucan_tx_abort(struct peak_canfd_priv *priv, u16 flags)
{
        struct pucan_tx_abort *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TX_ABORT);

        cmd->flags = cpu_to_le16(flags);

        return pucan_write_cmd(priv);
}

static int pucan_clr_err_counters(struct peak_canfd_priv *priv)
{
        struct pucan_wr_err_cnt *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_WR_ERR_CNT);

        cmd->sel_mask = cpu_to_le16(PUCAN_WRERRCNT_TE | PUCAN_WRERRCNT_RE);
        cmd->tx_counter = 0;
        cmd->rx_counter = 0;

        return pucan_write_cmd(priv);
}

static int pucan_set_options(struct peak_canfd_priv *priv, u16 opt_mask)
{
        struct pucan_options *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_EN_OPTION);

        cmd->options = cpu_to_le16(opt_mask);

        return pucan_write_cmd(priv);
}

static int pucan_clr_options(struct peak_canfd_priv *priv, u16 opt_mask)
{
        struct pucan_options *cmd;

        cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_CLR_DIS_OPTION);

        cmd->options = cpu_to_le16(opt_mask);

        return pucan_write_cmd(priv);
}

static int pucan_setup_rx_barrier(struct peak_canfd_priv *priv)
{
        pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RX_BARRIER);

        return pucan_write_cmd(priv);
}

/* handle the reception of one CAN frame */
static int pucan_handle_can_rx(struct peak_canfd_priv *priv,
                               struct pucan_rx_msg *msg)
{
        struct net_device_stats *stats = &priv->ndev->stats;
        struct canfd_frame *cf;
        struct sk_buff *skb;
        const u16 rx_msg_flags = le16_to_cpu(msg->flags);
        u8 cf_len;

        if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN)
                cf_len = can_dlc2len(get_canfd_dlc(pucan_msg_get_dlc(msg)));
        else
                cf_len = get_can_dlc(pucan_msg_get_dlc(msg));

        /* if this frame is an echo, */
        if ((rx_msg_flags & PUCAN_MSG_LOOPED_BACK) &&
            !(rx_msg_flags & PUCAN_MSG_SELF_RECEIVE)) {
                unsigned long flags;

                spin_lock_irqsave(&priv->echo_lock, flags);
                can_get_echo_skb(priv->ndev, msg->client);

                /* count bytes of the echo instead of skb */
                stats->tx_bytes += cf_len;
                stats->tx_packets++;

                /* restart tx queue (a slot is free) */
                netif_wake_queue(priv->ndev);

                spin_unlock_irqrestore(&priv->echo_lock, flags);
                return 0;
        }

        /* otherwise, it should be pushed into rx fifo */
        if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN) {
                /* CANFD frame case */
                skb = alloc_canfd_skb(priv->ndev, &cf);
                if (!skb)
                        return -ENOMEM;

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

                if (rx_msg_flags & PUCAN_MSG_ERROR_STATE_IND)
                        cf->flags |= CANFD_ESI;
        } else {
                /* CAN 2.0 frame case */
                skb = alloc_can_skb(priv->ndev, (struct can_frame **)&cf);
                if (!skb)
                        return -ENOMEM;
        }

        cf->can_id = le32_to_cpu(msg->can_id);
        cf->len = cf_len;

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

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

        stats->rx_bytes += cf->len;
        stats->rx_packets++;

        netif_rx(skb);

        return 0;
}

/* handle rx/tx error counters notification */
static int pucan_handle_error(struct peak_canfd_priv *priv,
                              struct pucan_error_msg *msg)
{
        priv->bec.txerr = msg->tx_err_cnt;
        priv->bec.rxerr = msg->rx_err_cnt;

        return 0;
}

/* handle status notification */
static int pucan_handle_status(struct peak_canfd_priv *priv,
                               struct pucan_status_msg *msg)
{
        struct net_device *ndev = priv->ndev;
        struct net_device_stats *stats = &ndev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;

        /* this STATUS is the CNF of the RX_BARRIER: Tx path can be setup */
        if (pucan_status_is_rx_barrier(msg)) {

                if (priv->enable_tx_path) {
                        int err = priv->enable_tx_path(priv);

                        if (err)
                                return err;
                }

                /* start network queue (echo_skb array is empty) */
                netif_start_queue(ndev);

                return 0;
        }

        skb = alloc_can_err_skb(ndev, &cf);

        /* test state error bits according to their priority */
        if (pucan_status_is_busoff(msg)) {
                netdev_dbg(ndev, "Bus-off entry status\n");
                priv->can.state = CAN_STATE_BUS_OFF;
                priv->can.can_stats.bus_off++;
                can_bus_off(ndev);
                if (skb)
                        cf->can_id |= CAN_ERR_BUSOFF;

        } else if (pucan_status_is_passive(msg)) {
                netdev_dbg(ndev, "Error passive status\n");
                priv->can.state = CAN_STATE_ERROR_PASSIVE;
                priv->can.can_stats.error_passive++;
                if (skb) {
                        cf->can_id |= CAN_ERR_CRTL;
                        cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
                                        CAN_ERR_CRTL_TX_PASSIVE :
                                        CAN_ERR_CRTL_RX_PASSIVE;
                        cf->data[6] = priv->bec.txerr;
                        cf->data[7] = priv->bec.rxerr;
                }

        } else if (pucan_status_is_warning(msg)) {
                netdev_dbg(ndev, "Error warning status\n");
                priv->can.state = CAN_STATE_ERROR_WARNING;
                priv->can.can_stats.error_warning++;
                if (skb) {
                        cf->can_id |= CAN_ERR_CRTL;
                        cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
                                        CAN_ERR_CRTL_TX_WARNING :
                                        CAN_ERR_CRTL_RX_WARNING;
                        cf->data[6] = priv->bec.txerr;
                        cf->data[7] = priv->bec.rxerr;
                }

        } else if (priv->can.state != CAN_STATE_ERROR_ACTIVE) {
                /* back to ERROR_ACTIVE */
                netdev_dbg(ndev, "Error active status\n");
                can_change_state(ndev, cf, CAN_STATE_ERROR_ACTIVE,
                                 CAN_STATE_ERROR_ACTIVE);
        } else {
                dev_kfree_skb(skb);
                return 0;
        }

        if (!skb) {
                stats->rx_dropped++;
                return -ENOMEM;
        }

        stats->rx_packets++;
        stats->rx_bytes += cf->can_dlc;
        netif_rx(skb);

        return 0;
}

/* handle uCAN Rx overflow notification */
static int pucan_handle_cache_critical(struct peak_canfd_priv *priv)
{
        struct net_device_stats *stats = &priv->ndev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;

        stats->rx_over_errors++;
        stats->rx_errors++;

        skb = alloc_can_err_skb(priv->ndev, &cf);
        if (!skb) {
                stats->rx_dropped++;
                return -ENOMEM;
        }

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

        cf->data[6] = priv->bec.txerr;
        cf->data[7] = priv->bec.rxerr;

        stats->rx_bytes += cf->can_dlc;
        stats->rx_packets++;
        netif_rx(skb);

        return 0;
}

/* handle a single uCAN message */
int peak_canfd_handle_msg(struct peak_canfd_priv *priv,
                          struct pucan_rx_msg *msg)
{
        u16 msg_type = le16_to_cpu(msg->type);
        int msg_size = le16_to_cpu(msg->size);
        int err;

        if (!msg_size || !msg_type) {
                /* null packet found: end of list */
                goto exit;
        }

        switch (msg_type) {
        case PUCAN_MSG_CAN_RX:
                err = pucan_handle_can_rx(priv, (struct pucan_rx_msg *)msg);
                break;
        case PUCAN_MSG_ERROR:
                err = pucan_handle_error(priv, (struct pucan_error_msg *)msg);
                break;
        case PUCAN_MSG_STATUS:
                err = pucan_handle_status(priv, (struct pucan_status_msg *)msg);
                break;
        case PUCAN_MSG_CACHE_CRITICAL:
                err = pucan_handle_cache_critical(priv);
                break;
        default:
                err = 0;
        }

        if (err < 0)
                return err;

exit:
        return msg_size;
}

/* handle a list of rx_count messages from rx_msg memory address */
int peak_canfd_handle_msgs_list(struct peak_canfd_priv *priv,
                                struct pucan_rx_msg *msg_list, int msg_count)
{
        void *msg_ptr = msg_list;
        int i, msg_size = 0;

        for (i = 0; i < msg_count; i++) {
                msg_size = peak_canfd_handle_msg(priv, msg_ptr);

                /* a null packet can be found at the end of a list */
                if (msg_size <= 0)
                        break;

                msg_ptr += msg_size;
        }

        if (msg_size < 0)
                return msg_size;

        return i;
}

static int peak_canfd_start(struct peak_canfd_priv *priv)
{
        int err;

        err = pucan_clr_err_counters(priv);
        if (err)
                goto err_exit;

        priv->echo_idx = 0;

        priv->bec.txerr = 0;
        priv->bec.rxerr = 0;

        if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                err = pucan_set_listen_only_mode(priv);
        else
                err = pucan_set_normal_mode(priv);

err_exit:
        return err;
}

static void peak_canfd_stop(struct peak_canfd_priv *priv)
{
        int err;

        /* go back to RESET mode */
        err = pucan_set_reset_mode(priv);
        if (err) {
                netdev_err(priv->ndev, "channel %u reset failed\n",
                           priv->index);
        } else {
                /* abort last Tx (MUST be done in RESET mode only!) */
                pucan_tx_abort(priv, PUCAN_TX_ABORT_FLUSH);
        }
}

static int peak_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);

        switch (mode) {
        case CAN_MODE_START:
                peak_canfd_start(priv);
                netif_wake_queue(ndev);
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int peak_canfd_get_berr_counter(const struct net_device *ndev,
                                       struct can_berr_counter *bec)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);

        *bec = priv->bec;
        return 0;
}

static int peak_canfd_open(struct net_device *ndev)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);
        int i, err = 0;

        err = open_candev(ndev);
        if (err) {
                netdev_err(ndev, "open_candev() failed, error %d\n", err);
                goto err_exit;
        }

        err = pucan_set_reset_mode(priv);
        if (err)
                goto err_close;

        if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
                if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
                        err = pucan_clr_options(priv, PUCAN_OPTION_CANDFDISO);
                else
                        err = pucan_set_options(priv, PUCAN_OPTION_CANDFDISO);

                if (err)
                        goto err_close;
        }

        /* set option: get rx/tx error counters */
        err = pucan_set_options(priv, PUCAN_OPTION_ERROR);
        if (err)
                goto err_close;

        /* accept all standard CAN ID */
        for (i = 0; i <= PUCAN_FLTSTD_ROW_IDX_MAX; i++)
                pucan_set_std_filter(priv, i, 0xffffffff);

        err = peak_canfd_start(priv);
        if (err)
                goto err_close;

        /* receiving the RB status says when Tx path is ready */
        err = pucan_setup_rx_barrier(priv);
        if (!err)
                goto err_exit;

err_close:
        close_candev(ndev);
err_exit:
        return err;
}

static int peak_canfd_set_bittiming(struct net_device *ndev)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);

        return pucan_set_timing_slow(priv, &priv->can.bittiming);
}

static int peak_canfd_set_data_bittiming(struct net_device *ndev)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);

        return pucan_set_timing_fast(priv, &priv->can.data_bittiming);
}

static int peak_canfd_close(struct net_device *ndev)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);

        netif_stop_queue(ndev);
        peak_canfd_stop(priv);
        close_candev(ndev);

        return 0;
}

static netdev_tx_t peak_canfd_start_xmit(struct sk_buff *skb,
                                         struct net_device *ndev)
{
        struct peak_canfd_priv *priv = netdev_priv(ndev);
        struct net_device_stats *stats = &ndev->stats;
        struct canfd_frame *cf = (struct canfd_frame *)skb->data;
        struct pucan_tx_msg *msg;
        u16 msg_size, msg_flags;
        unsigned long flags;
        bool should_stop_tx_queue;
        int room_left;
        u8 can_dlc;

        if (can_dropped_invalid_skb(ndev, skb))
                return NETDEV_TX_OK;

        msg_size = ALIGN(sizeof(*msg) + cf->len, 4);
        msg = priv->alloc_tx_msg(priv, msg_size, &room_left);

        /* should never happen except under bus-off condition and (auto-)restart
         * mechanism
         */
        if (!msg) {
                stats->tx_dropped++;
                netif_stop_queue(ndev);
                return NETDEV_TX_BUSY;
        }

        msg->size = cpu_to_le16(msg_size);
        msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);
        msg_flags = 0;

        if (cf->can_id & CAN_EFF_FLAG) {
                msg_flags |= PUCAN_MSG_EXT_ID;
                msg->can_id = cpu_to_le32(cf->can_id & CAN_EFF_MASK);
        } else {
                msg->can_id = cpu_to_le32(cf->can_id & CAN_SFF_MASK);
        }

        if (can_is_canfd_skb(skb)) {
                /* CAN FD frame format */
                can_dlc = can_len2dlc(cf->len);

                msg_flags |= PUCAN_MSG_EXT_DATA_LEN;

                if (cf->flags & CANFD_BRS)
                        msg_flags |= PUCAN_MSG_BITRATE_SWITCH;

                if (cf->flags & CANFD_ESI)
                        msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
        } else {
                /* CAN 2.0 frame format */
                can_dlc = cf->len;

                if (cf->can_id & CAN_RTR_FLAG)
                        msg_flags |= PUCAN_MSG_RTR;
        }

        /* always ask loopback for echo management */
        msg_flags |= PUCAN_MSG_LOOPED_BACK;

        /* set driver specific bit to differentiate with application loopback */
        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
                msg_flags |= PUCAN_MSG_SELF_RECEIVE;

        msg->flags = cpu_to_le16(msg_flags);
        msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(priv->index, can_dlc);
        memcpy(msg->d, cf->data, cf->len);

        /* struct msg client field is used as an index in the echo skbs ring */
        msg->client = priv->echo_idx;

        spin_lock_irqsave(&priv->echo_lock, flags);

        /* prepare and save echo skb in internal slot */
        can_put_echo_skb(skb, ndev, priv->echo_idx);

        /* move echo index to the next slot */
        priv->echo_idx = (priv->echo_idx + 1) % priv->can.echo_skb_max;

        /* if next slot is not free, stop network queue (no slot free in echo
         * skb ring means that the controller did not write these frames on
         * the bus: no need to continue).
         */
        should_stop_tx_queue = !!(priv->can.echo_skb[priv->echo_idx]);

        /* stop network tx queue if not enough room to save one more msg too */
        if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
                should_stop_tx_queue |= (room_left <
                                        (sizeof(*msg) + CANFD_MAX_DLEN));
        else
                should_stop_tx_queue |= (room_left <
                                        (sizeof(*msg) + CAN_MAX_DLEN));

        if (should_stop_tx_queue)
                netif_stop_queue(ndev);

        spin_unlock_irqrestore(&priv->echo_lock, flags);

        /* write the skb on the interface */
        priv->write_tx_msg(priv, msg);

        return NETDEV_TX_OK;
}

static const struct net_device_ops peak_canfd_netdev_ops = {
        .ndo_open = peak_canfd_open,
        .ndo_stop = peak_canfd_close,
        .ndo_start_xmit = peak_canfd_start_xmit,
        .ndo_change_mtu = can_change_mtu,
};

struct net_device *alloc_peak_canfd_dev(int sizeof_priv, int index,
                                        int echo_skb_max)
{
        struct net_device *ndev;
        struct peak_canfd_priv *priv;

        /* we DO support local echo */
        if (echo_skb_max < 0)
                echo_skb_max = PCANFD_ECHO_SKB_MAX;

        /* allocate the candev object */
        ndev = alloc_candev(sizeof_priv, echo_skb_max);
        if (!ndev)
                return NULL;

        priv = netdev_priv(ndev);

        /* complete now socket-can initialization side */
        priv->can.state = CAN_STATE_STOPPED;
        priv->can.bittiming_const = &peak_canfd_nominal_const;
        priv->can.data_bittiming_const = &peak_canfd_data_const;

        priv->can.do_set_mode = peak_canfd_set_mode;
        priv->can.do_get_berr_counter = peak_canfd_get_berr_counter;
        priv->can.do_set_bittiming = peak_canfd_set_bittiming;
        priv->can.do_set_data_bittiming = peak_canfd_set_data_bittiming;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
                                       CAN_CTRLMODE_LISTENONLY |
                                       CAN_CTRLMODE_3_SAMPLES |
                                       CAN_CTRLMODE_FD |
                                       CAN_CTRLMODE_FD_NON_ISO |
                                       CAN_CTRLMODE_BERR_REPORTING;

        priv->ndev = ndev;
        priv->index = index;
        priv->cmd_len = 0;
        spin_lock_init(&priv->echo_lock);

        ndev->flags |= IFF_ECHO;
        ndev->netdev_ops = &peak_canfd_netdev_ops;
        ndev->dev_id = index;

        return ndev;
}