// SPDX-License-Identifier: GPL-2.0-only
/*
 * CAN driver for PEAK System USB adapters
 * Derived from the PCAN project file driver/src/pcan_usb_core.c
 *
 * Copyright (C) 2003-2010 PEAK System-Technik GmbH
 * Copyright (C) 2010-2012 Stephane Grosjean <s.grosjean@peak-system.com>
 *
 * Many thanks to Klaus Hitschler <klaus.hitschler@gmx.de>
 */
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/usb.h>

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

#include "pcan_usb_core.h"

MODULE_AUTHOR("Stephane Grosjean <s.grosjean@peak-system.com>");
MODULE_DESCRIPTION("CAN driver for PEAK-System USB adapters");
MODULE_LICENSE("GPL v2");

/* Table of devices that work with this driver */
static struct usb_device_id peak_usb_table[] = {
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USB_PRODUCT_ID)},
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBPRO_PRODUCT_ID)},
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBFD_PRODUCT_ID)},
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBPROFD_PRODUCT_ID)},
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBCHIP_PRODUCT_ID)},
        {USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBX6_PRODUCT_ID)},
        {} /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, peak_usb_table);

/* List of supported PCAN-USB adapters (NULL terminated list) */
static const struct peak_usb_adapter *const peak_usb_adapters_list[] = {
        &pcan_usb,
        &pcan_usb_pro,
        &pcan_usb_fd,
        &pcan_usb_pro_fd,
        &pcan_usb_chip,
        &pcan_usb_x6,
};

/*
 * dump memory
 */
#define DUMP_WIDTH      16
void pcan_dump_mem(char *prompt, void *p, int l)
{
        pr_info("%s dumping %s (%d bytes):\n",
                PCAN_USB_DRIVER_NAME, prompt ? prompt : "memory", l);
        print_hex_dump(KERN_INFO, PCAN_USB_DRIVER_NAME " ", DUMP_PREFIX_NONE,
                       DUMP_WIDTH, 1, p, l, false);
}

/*
 * initialize a time_ref object with usb adapter own settings
 */
void peak_usb_init_time_ref(struct peak_time_ref *time_ref,
                            const struct peak_usb_adapter *adapter)
{
        if (time_ref) {
                memset(time_ref, 0, sizeof(struct peak_time_ref));
                time_ref->adapter = adapter;
        }
}

/*
 * sometimes, another now may be  more recent than current one...
 */
void peak_usb_update_ts_now(struct peak_time_ref *time_ref, u32 ts_now)
{
        time_ref->ts_dev_2 = ts_now;

        /* should wait at least two passes before computing */
        if (ktime_to_ns(time_ref->tv_host) > 0) {
                u32 delta_ts = time_ref->ts_dev_2 - time_ref->ts_dev_1;

                if (time_ref->ts_dev_2 < time_ref->ts_dev_1)
                        delta_ts &= (1 << time_ref->adapter->ts_used_bits) - 1;

                time_ref->ts_total += delta_ts;
        }
}

/*
 * register device timestamp as now
 */
void peak_usb_set_ts_now(struct peak_time_ref *time_ref, u32 ts_now)
{
        if (ktime_to_ns(time_ref->tv_host_0) == 0) {
                /* use monotonic clock to correctly compute further deltas */
                time_ref->tv_host_0 = ktime_get();
                time_ref->tv_host = ktime_set(0, 0);
        } else {
                /*
                 * delta_us should not be >= 2^32 => delta should be < 4294s
                 * handle 32-bits wrapping here: if count of s. reaches 4200,
                 * reset counters and change time base
                 */
                if (ktime_to_ns(time_ref->tv_host)) {
                        ktime_t delta = ktime_sub(time_ref->tv_host,
                                                  time_ref->tv_host_0);
                        if (ktime_to_ns(delta) > (4200ull * NSEC_PER_SEC)) {
                                time_ref->tv_host_0 = time_ref->tv_host;
                                time_ref->ts_total = 0;
                        }
                }

                time_ref->tv_host = ktime_get();
                time_ref->tick_count++;
        }

        time_ref->ts_dev_1 = time_ref->ts_dev_2;
        peak_usb_update_ts_now(time_ref, ts_now);
}

/*
 * compute time according to current ts and time_ref data
 */
void peak_usb_get_ts_time(struct peak_time_ref *time_ref, u32 ts, ktime_t *time)
{
        /* protect from getting time before setting now */
        if (ktime_to_ns(time_ref->tv_host)) {
                u64 delta_us;

                delta_us = ts - time_ref->ts_dev_2;
                if (ts < time_ref->ts_dev_2)
                        delta_us &= (1 << time_ref->adapter->ts_used_bits) - 1;

                delta_us += time_ref->ts_total;

                delta_us *= time_ref->adapter->us_per_ts_scale;
                delta_us >>= time_ref->adapter->us_per_ts_shift;

                *time = ktime_add_us(time_ref->tv_host_0, delta_us);
        } else {
                *time = ktime_get();
        }
}

/*
 * post received skb after having set any hw timestamp
 */
int peak_usb_netif_rx(struct sk_buff *skb,
                      struct peak_time_ref *time_ref, u32 ts_low)
{
        struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);

        peak_usb_get_ts_time(time_ref, ts_low, &hwts->hwtstamp);

        return netif_rx(skb);
}

/*
 * callback for bulk Rx urb
 */
static void peak_usb_read_bulk_callback(struct urb *urb)
{
        struct peak_usb_device *dev = urb->context;
        struct net_device *netdev;
        int err;

        netdev = dev->netdev;

        if (!netif_device_present(netdev))
                return;

        /* check reception status */
        switch (urb->status) {
        case 0:
                /* success */
                break;

        case -EILSEQ:
        case -ENOENT:
        case -ECONNRESET:
        case -ESHUTDOWN:
                return;

        default:
                if (net_ratelimit())
                        netdev_err(netdev,
                                   "Rx urb aborted (%d)\n", urb->status);
                goto resubmit_urb;
        }

        /* protect from any incoming empty msgs */
        if ((urb->actual_length > 0) && (dev->adapter->dev_decode_buf)) {
                /* handle these kinds of msgs only if _start callback called */
                if (dev->state & PCAN_USB_STATE_STARTED) {
                        err = dev->adapter->dev_decode_buf(dev, urb);
                        if (err)
                                pcan_dump_mem("received usb message",
                                              urb->transfer_buffer,
                                              urb->transfer_buffer_length);
                }
        }

resubmit_urb:
        usb_fill_bulk_urb(urb, dev->udev,
                usb_rcvbulkpipe(dev->udev, dev->ep_msg_in),
                urb->transfer_buffer, dev->adapter->rx_buffer_size,
                peak_usb_read_bulk_callback, dev);

        usb_anchor_urb(urb, &dev->rx_submitted);
        err = usb_submit_urb(urb, GFP_ATOMIC);
        if (!err)
                return;

        usb_unanchor_urb(urb);

        if (err == -ENODEV)
                netif_device_detach(netdev);
        else
                netdev_err(netdev, "failed resubmitting read bulk urb: %d\n",
                           err);
}

/*
 * callback for bulk Tx urb
 */
static void peak_usb_write_bulk_callback(struct urb *urb)
{
        struct peak_tx_urb_context *context = urb->context;
        struct peak_usb_device *dev;
        struct net_device *netdev;

        BUG_ON(!context);

        dev = context->dev;
        netdev = dev->netdev;

        atomic_dec(&dev->active_tx_urbs);

        if (!netif_device_present(netdev))
                return;

        /* check tx status */
        switch (urb->status) {
        case 0:
                /* transmission complete */
                netdev->stats.tx_packets++;
                netdev->stats.tx_bytes += context->data_len;

                /* prevent tx timeout */
                netif_trans_update(netdev);
                break;

        default:
                if (net_ratelimit())
                        netdev_err(netdev, "Tx urb aborted (%d)\n",
                                   urb->status);
        case -EPROTO:
        case -ENOENT:
        case -ECONNRESET:
        case -ESHUTDOWN:

                break;
        }

        /* should always release echo skb and corresponding context */
        can_get_echo_skb(netdev, context->echo_index);
        context->echo_index = PCAN_USB_MAX_TX_URBS;

        /* do wakeup tx queue in case of success only */
        if (!urb->status)
                netif_wake_queue(netdev);
}

/*
 * called by netdev to send one skb on the CAN interface.
 */
static netdev_tx_t peak_usb_ndo_start_xmit(struct sk_buff *skb,
                                           struct net_device *netdev)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        struct peak_tx_urb_context *context = NULL;
        struct net_device_stats *stats = &netdev->stats;
        struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
        struct urb *urb;
        u8 *obuf;
        int i, err;
        size_t size = dev->adapter->tx_buffer_size;

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

        for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++)
                if (dev->tx_contexts[i].echo_index == PCAN_USB_MAX_TX_URBS) {
                        context = dev->tx_contexts + i;
                        break;
                }

        if (!context) {
                /* should not occur except during restart */
                return NETDEV_TX_BUSY;
        }

        urb = context->urb;
        obuf = urb->transfer_buffer;

        err = dev->adapter->dev_encode_msg(dev, skb, obuf, &size);
        if (err) {
                if (net_ratelimit())
                        netdev_err(netdev, "packet dropped\n");
                dev_kfree_skb(skb);
                stats->tx_dropped++;
                return NETDEV_TX_OK;
        }

        context->echo_index = i;

        /* Note: this works with CANFD frames too */
        context->data_len = cfd->len;

        usb_anchor_urb(urb, &dev->tx_submitted);

        can_put_echo_skb(skb, netdev, context->echo_index);

        atomic_inc(&dev->active_tx_urbs);

        err = usb_submit_urb(urb, GFP_ATOMIC);
        if (err) {
                can_free_echo_skb(netdev, context->echo_index);

                usb_unanchor_urb(urb);

                /* this context is not used in fact */
                context->echo_index = PCAN_USB_MAX_TX_URBS;

                atomic_dec(&dev->active_tx_urbs);

                switch (err) {
                case -ENODEV:
                        netif_device_detach(netdev);
                        break;
                default:
                        netdev_warn(netdev, "tx urb submitting failed err=%d\n",
                                    err);
                        /* fall through */
                case -ENOENT:
                        /* cable unplugged */
                        stats->tx_dropped++;
                }
        } else {
                netif_trans_update(netdev);

                /* slow down tx path */
                if (atomic_read(&dev->active_tx_urbs) >= PCAN_USB_MAX_TX_URBS)
                        netif_stop_queue(netdev);
        }

        return NETDEV_TX_OK;
}

/*
 * start the CAN interface.
 * Rx and Tx urbs are allocated here. Rx urbs are submitted here.
 */
static int peak_usb_start(struct peak_usb_device *dev)
{
        struct net_device *netdev = dev->netdev;
        int err, i;

        for (i = 0; i < PCAN_USB_MAX_RX_URBS; i++) {
                struct urb *urb;
                u8 *buf;

                /* create a URB, and a buffer for it, to receive usb messages */
                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        err = -ENOMEM;
                        break;
                }

                buf = kmalloc(dev->adapter->rx_buffer_size, GFP_KERNEL);
                if (!buf) {
                        usb_free_urb(urb);
                        err = -ENOMEM;
                        break;
                }

                usb_fill_bulk_urb(urb, dev->udev,
                        usb_rcvbulkpipe(dev->udev, dev->ep_msg_in),
                        buf, dev->adapter->rx_buffer_size,
                        peak_usb_read_bulk_callback, dev);

                /* ask last usb_free_urb() to also kfree() transfer_buffer */
                urb->transfer_flags |= URB_FREE_BUFFER;
                usb_anchor_urb(urb, &dev->rx_submitted);

                err = usb_submit_urb(urb, GFP_KERNEL);
                if (err) {
                        if (err == -ENODEV)
                                netif_device_detach(dev->netdev);

                        usb_unanchor_urb(urb);
                        kfree(buf);
                        usb_free_urb(urb);
                        break;
                }

                /* drop reference, USB core will take care of freeing it */
                usb_free_urb(urb);
        }

        /* did we submit any URBs? Warn if we was not able to submit all urbs */
        if (i < PCAN_USB_MAX_RX_URBS) {
                if (i == 0) {
                        netdev_err(netdev, "couldn't setup any rx URB\n");
                        return err;
                }

                netdev_warn(netdev, "rx performance may be slow\n");
        }

        /* pre-alloc tx buffers and corresponding urbs */
        for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++) {
                struct peak_tx_urb_context *context;
                struct urb *urb;
                u8 *buf;

                /* create a URB and a buffer for it, to transmit usb messages */
                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        err = -ENOMEM;
                        break;
                }

                buf = kmalloc(dev->adapter->tx_buffer_size, GFP_KERNEL);
                if (!buf) {
                        usb_free_urb(urb);
                        err = -ENOMEM;
                        break;
                }

                context = dev->tx_contexts + i;
                context->dev = dev;
                context->urb = urb;

                usb_fill_bulk_urb(urb, dev->udev,
                        usb_sndbulkpipe(dev->udev, dev->ep_msg_out),
                        buf, dev->adapter->tx_buffer_size,
                        peak_usb_write_bulk_callback, context);

                /* ask last usb_free_urb() to also kfree() transfer_buffer */
                urb->transfer_flags |= URB_FREE_BUFFER;
        }

        /* warn if we were not able to allocate enough tx contexts */
        if (i < PCAN_USB_MAX_TX_URBS) {
                if (i == 0) {
                        netdev_err(netdev, "couldn't setup any tx URB\n");
                        goto err_tx;
                }

                netdev_warn(netdev, "tx performance may be slow\n");
        }

        if (dev->adapter->dev_start) {
                err = dev->adapter->dev_start(dev);
                if (err)
                        goto err_adapter;
        }

        dev->state |= PCAN_USB_STATE_STARTED;

        /* can set bus on now */
        if (dev->adapter->dev_set_bus) {
                err = dev->adapter->dev_set_bus(dev, 1);
                if (err)
                        goto err_adapter;
        }

        dev->can.state = CAN_STATE_ERROR_ACTIVE;

        return 0;

err_adapter:
        if (err == -ENODEV)
                netif_device_detach(dev->netdev);

        netdev_warn(netdev, "couldn't submit control: %d\n", err);

        for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++) {
                usb_free_urb(dev->tx_contexts[i].urb);
                dev->tx_contexts[i].urb = NULL;
        }
err_tx:
        usb_kill_anchored_urbs(&dev->rx_submitted);

        return err;
}

/*
 * called by netdev to open the corresponding CAN interface.
 */
static int peak_usb_ndo_open(struct net_device *netdev)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        int err;

        /* common open */
        err = open_candev(netdev);
        if (err)
                return err;

        /* finally start device */
        err = peak_usb_start(dev);
        if (err) {
                netdev_err(netdev, "couldn't start device: %d\n", err);
                close_candev(netdev);
                return err;
        }

        netif_start_queue(netdev);

        return 0;
}

/*
 * unlink in-flight Rx and Tx urbs and free their memory.
 */
static void peak_usb_unlink_all_urbs(struct peak_usb_device *dev)
{
        int i;

        /* free all Rx (submitted) urbs */
        usb_kill_anchored_urbs(&dev->rx_submitted);

        /* free unsubmitted Tx urbs first */
        for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++) {
                struct urb *urb = dev->tx_contexts[i].urb;

                if (!urb ||
                    dev->tx_contexts[i].echo_index != PCAN_USB_MAX_TX_URBS) {
                        /*
                         * this urb is already released or always submitted,
                         * let usb core free by itself
                         */
                        continue;
                }

                usb_free_urb(urb);
                dev->tx_contexts[i].urb = NULL;
        }

        /* then free all submitted Tx urbs */
        usb_kill_anchored_urbs(&dev->tx_submitted);
        atomic_set(&dev->active_tx_urbs, 0);
}

/*
 * called by netdev to close the corresponding CAN interface.
 */
static int peak_usb_ndo_stop(struct net_device *netdev)
{
        struct peak_usb_device *dev = netdev_priv(netdev);

        dev->state &= ~PCAN_USB_STATE_STARTED;
        netif_stop_queue(netdev);

        close_candev(netdev);

        dev->can.state = CAN_STATE_STOPPED;

        /* unlink all pending urbs and free used memory */
        peak_usb_unlink_all_urbs(dev);

        if (dev->adapter->dev_stop)
                dev->adapter->dev_stop(dev);

        /* can set bus off now */
        if (dev->adapter->dev_set_bus) {
                int err = dev->adapter->dev_set_bus(dev, 0);
                if (err)
                        return err;
        }

        return 0;
}

/*
 * handle end of waiting for the device to reset
 */
void peak_usb_restart_complete(struct peak_usb_device *dev)
{
        /* finally MUST update can state */
        dev->can.state = CAN_STATE_ERROR_ACTIVE;

        /* netdev queue can be awaken now */
        netif_wake_queue(dev->netdev);
}

void peak_usb_async_complete(struct urb *urb)
{
        kfree(urb->transfer_buffer);
        usb_free_urb(urb);
}

/*
 * device (auto-)restart mechanism runs in a timer context =>
 * MUST handle restart with asynchronous usb transfers
 */
static int peak_usb_restart(struct peak_usb_device *dev)
{
        struct urb *urb;
        int err;
        u8 *buf;

        /*
         * if device doesn't define any asynchronous restart handler, simply
         * wake the netdev queue up
         */
        if (!dev->adapter->dev_restart_async) {
                peak_usb_restart_complete(dev);
                return 0;
        }

        /* first allocate a urb to handle the asynchronous steps */
        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb)
                return -ENOMEM;

        /* also allocate enough space for the commands to send */
        buf = kmalloc(PCAN_USB_MAX_CMD_LEN, GFP_ATOMIC);
        if (!buf) {
                usb_free_urb(urb);
                return -ENOMEM;
        }

        /* call the device specific handler for the restart */
        err = dev->adapter->dev_restart_async(dev, urb, buf);
        if (!err)
                return 0;

        kfree(buf);
        usb_free_urb(urb);

        return err;
}

/*
 * candev callback used to change CAN mode.
 * Warning: this is called from a timer context!
 */
static int peak_usb_set_mode(struct net_device *netdev, enum can_mode mode)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        int err = 0;

        switch (mode) {
        case CAN_MODE_START:
                err = peak_usb_restart(dev);
                if (err)
                        netdev_err(netdev, "couldn't start device (err %d)\n",
                                   err);
                break;

        default:
                return -EOPNOTSUPP;
        }

        return err;
}

/*
 * candev callback used to set device nominal/arbitration bitrate.
 */
static int peak_usb_set_bittiming(struct net_device *netdev)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        const struct peak_usb_adapter *pa = dev->adapter;

        if (pa->dev_set_bittiming) {
                struct can_bittiming *bt = &dev->can.bittiming;
                int err = pa->dev_set_bittiming(dev, bt);

                if (err)
                        netdev_info(netdev, "couldn't set bitrate (err %d)\n",
                                    err);
                return err;
        }

        return 0;
}

/*
 * candev callback used to set device data bitrate.
 */
static int peak_usb_set_data_bittiming(struct net_device *netdev)
{
        struct peak_usb_device *dev = netdev_priv(netdev);
        const struct peak_usb_adapter *pa = dev->adapter;

        if (pa->dev_set_data_bittiming) {
                struct can_bittiming *bt = &dev->can.data_bittiming;
                int err = pa->dev_set_data_bittiming(dev, bt);

                if (err)
                        netdev_info(netdev,
                                    "couldn't set data bitrate (err %d)\n",
                                    err);

                return err;
        }

        return 0;
}

static const struct net_device_ops peak_usb_netdev_ops = {
        .ndo_open = peak_usb_ndo_open,
        .ndo_stop = peak_usb_ndo_stop,
        .ndo_start_xmit = peak_usb_ndo_start_xmit,
        .ndo_change_mtu = can_change_mtu,
};

/*
 * create one device which is attached to CAN controller #ctrl_idx of the
 * usb adapter.
 */
static int peak_usb_create_dev(const struct peak_usb_adapter *peak_usb_adapter,
                               struct usb_interface *intf, int ctrl_idx)
{
        struct usb_device *usb_dev = interface_to_usbdev(intf);
        int sizeof_candev = peak_usb_adapter->sizeof_dev_private;
        struct peak_usb_device *dev;
        struct net_device *netdev;
        int i, err;
        u16 tmp16;

        if (sizeof_candev < sizeof(struct peak_usb_device))
                sizeof_candev = sizeof(struct peak_usb_device);

        netdev = alloc_candev(sizeof_candev, PCAN_USB_MAX_TX_URBS);
        if (!netdev) {
                dev_err(&intf->dev, "%s: couldn't alloc candev\n",
                        PCAN_USB_DRIVER_NAME);
                return -ENOMEM;
        }

        dev = netdev_priv(netdev);

        /* allocate a buffer large enough to send commands */
        dev->cmd_buf = kmalloc(PCAN_USB_MAX_CMD_LEN, GFP_KERNEL);
        if (!dev->cmd_buf) {
                err = -ENOMEM;
                goto lbl_free_candev;
        }

        dev->udev = usb_dev;
        dev->netdev = netdev;
        dev->adapter = peak_usb_adapter;
        dev->ctrl_idx = ctrl_idx;
        dev->state = PCAN_USB_STATE_CONNECTED;

        dev->ep_msg_in = peak_usb_adapter->ep_msg_in;
        dev->ep_msg_out = peak_usb_adapter->ep_msg_out[ctrl_idx];

        dev->can.clock = peak_usb_adapter->clock;
        dev->can.bittiming_const = peak_usb_adapter->bittiming_const;
        dev->can.do_set_bittiming = peak_usb_set_bittiming;
        dev->can.data_bittiming_const = peak_usb_adapter->data_bittiming_const;
        dev->can.do_set_data_bittiming = peak_usb_set_data_bittiming;
        dev->can.do_set_mode = peak_usb_set_mode;
        dev->can.do_get_berr_counter = peak_usb_adapter->do_get_berr_counter;
        dev->can.ctrlmode_supported = peak_usb_adapter->ctrlmode_supported;

        netdev->netdev_ops = &peak_usb_netdev_ops;

        netdev->flags |= IFF_ECHO; /* we support local echo */

        init_usb_anchor(&dev->rx_submitted);

        init_usb_anchor(&dev->tx_submitted);
        atomic_set(&dev->active_tx_urbs, 0);

        for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++)
                dev->tx_contexts[i].echo_index = PCAN_USB_MAX_TX_URBS;

        dev->prev_siblings = usb_get_intfdata(intf);
        usb_set_intfdata(intf, dev);

        SET_NETDEV_DEV(netdev, &intf->dev);
        netdev->dev_id = ctrl_idx;

        err = register_candev(netdev);
        if (err) {
                dev_err(&intf->dev, "couldn't register CAN device: %d\n", err);
                goto lbl_restore_intf_data;
        }

        if (dev->prev_siblings)
                (dev->prev_siblings)->next_siblings = dev;

        /* keep hw revision into the netdevice */
        tmp16 = le16_to_cpu(usb_dev->descriptor.bcdDevice);
        dev->device_rev = tmp16 >> 8;

        if (dev->adapter->dev_init) {
                err = dev->adapter->dev_init(dev);
                if (err)
                        goto lbl_unregister_candev;
        }

        /* set bus off */
        if (dev->adapter->dev_set_bus) {
                err = dev->adapter->dev_set_bus(dev, 0);
                if (err)
                        goto lbl_unregister_candev;
        }

        /* get device number early */
        if (dev->adapter->dev_get_device_id)
                dev->adapter->dev_get_device_id(dev, &dev->device_number);

        netdev_info(netdev, "attached to %s channel %u (device %u)\n",
                        peak_usb_adapter->name, ctrl_idx, dev->device_number);

        return 0;

lbl_unregister_candev:
        unregister_candev(netdev);

lbl_restore_intf_data:
        usb_set_intfdata(intf, dev->prev_siblings);
        kfree(dev->cmd_buf);

lbl_free_candev:
        free_candev(netdev);

        return err;
}

/*
 * called by the usb core when the device is unplugged from the system
 */
static void peak_usb_disconnect(struct usb_interface *intf)
{
        struct peak_usb_device *dev;
        struct peak_usb_device *dev_prev_siblings;

        /* unregister as many netdev devices as siblings */
        for (dev = usb_get_intfdata(intf); dev; dev = dev_prev_siblings) {
                struct net_device *netdev = dev->netdev;
                char name[IFNAMSIZ];

                dev_prev_siblings = dev->prev_siblings;
                dev->state &= ~PCAN_USB_STATE_CONNECTED;
                strlcpy(name, netdev->name, IFNAMSIZ);

                unregister_netdev(netdev);

                kfree(dev->cmd_buf);
                dev->next_siblings = NULL;
                if (dev->adapter->dev_free)
                        dev->adapter->dev_free(dev);

                free_candev(netdev);
                dev_info(&intf->dev, "%s removed\n", name);
        }

        usb_set_intfdata(intf, NULL);
}

/*
 * probe function for new PEAK-System devices
 */
static int peak_usb_probe(struct usb_interface *intf,
                          const struct usb_device_id *id)
{
        struct usb_device *usb_dev = interface_to_usbdev(intf);
        const u16 usb_id_product = le16_to_cpu(usb_dev->descriptor.idProduct);
        const struct peak_usb_adapter *peak_usb_adapter = NULL;
        int i, err = -ENOMEM;

        /* get corresponding PCAN-USB adapter */
        for (i = 0; i < ARRAY_SIZE(peak_usb_adapters_list); i++)
                if (peak_usb_adapters_list[i]->device_id == usb_id_product) {
                        peak_usb_adapter = peak_usb_adapters_list[i];
                        break;
                }

        if (!peak_usb_adapter) {
                /* should never come except device_id bad usage in this file */
                pr_err("%s: didn't find device id. 0x%x in devices list\n",
                        PCAN_USB_DRIVER_NAME, usb_id_product);
                return -ENODEV;
        }

        /* got corresponding adapter: check if it handles current interface */
        if (peak_usb_adapter->intf_probe) {
                err = peak_usb_adapter->intf_probe(intf);
                if (err)
                        return err;
        }

        for (i = 0; i < peak_usb_adapter->ctrl_count; i++) {
                err = peak_usb_create_dev(peak_usb_adapter, intf, i);
                if (err) {
                        /* deregister already created devices */
                        peak_usb_disconnect(intf);
                        break;
                }
        }

        return err;
}

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver peak_usb_driver = {
        .name = PCAN_USB_DRIVER_NAME,
        .disconnect = peak_usb_disconnect,
        .probe = peak_usb_probe,
        .id_table = peak_usb_table,
};

static int __init peak_usb_init(void)
{
        int err;

        /* register this driver with the USB subsystem */
        err = usb_register(&peak_usb_driver);
        if (err)
                pr_err("%s: usb_register failed (err %d)\n",
                        PCAN_USB_DRIVER_NAME, err);

        return err;
}

static int peak_usb_do_device_exit(struct device *d, void *arg)
{
        struct usb_interface *intf = to_usb_interface(d);
        struct peak_usb_device *dev;

        /* stop as many netdev devices as siblings */
        for (dev = usb_get_intfdata(intf); dev; dev = dev->prev_siblings) {
                struct net_device *netdev = dev->netdev;

                if (netif_device_present(netdev))
                        if (dev->adapter->dev_exit)
                                dev->adapter->dev_exit(dev);
        }

        return 0;
}

static void __exit peak_usb_exit(void)
{
        int err;

        /* last chance do send any synchronous commands here */
        err = driver_for_each_device(&peak_usb_driver.drvwrap.driver, NULL,
                                     NULL, peak_usb_do_device_exit);
        if (err)
                pr_err("%s: failed to stop all can devices (err %d)\n",
                        PCAN_USB_DRIVER_NAME, err);

        /* deregister this driver with the USB subsystem */
        usb_deregister(&peak_usb_driver);

        pr_info("%s: PCAN-USB interfaces driver unloaded\n",
                PCAN_USB_DRIVER_NAME);
}

module_init(peak_usb_init);
module_exit(peak_usb_exit);