pcan_usb_core.c

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/*
 * 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 <[email protected]>
 *
 * Many thanks to Klaus Hitschler <[email protected]>
 *
 * 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/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 <[email protected]>");
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)},
    {} /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, peak_usb_table);

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

/*
 * 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,
                struct peak_usb_adapter *adapter)
{
    if (time_ref) {
        memset(time_ref, 0, sizeof(struct peak_time_ref));
        time_ref->adapter = adapter;
    }
}

static void peak_usb_add_us(struct timeval *tv, u32 delta_us)
{
    /* number of s. to add to final time */
    u32 delta_s = delta_us / 1000000;

    delta_us -= delta_s * 1000000;

    tv->tv_usec += delta_us;
    if (tv->tv_usec >= 1000000) {
        tv->tv_usec -= 1000000;
        delta_s++;
    }
    tv->tv_sec += delta_s;
}

/*
 * 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 (time_ref->tv_host.tv_sec > 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 (time_ref->tv_host_0.tv_sec == 0) {
        /* use monotonic clock to correctly compute further deltas */
        time_ref->tv_host_0 = ktime_to_timeval(ktime_get());
        time_ref->tv_host.tv_sec = 0;
    } else {
        /*
         * delta_us should not be >= 2^32 => delta_s should be < 4294
         * handle 32-bits wrapping here: if count of s. reaches 4200,
         * reset counters and change time base
         */
        if (time_ref->tv_host.tv_sec != 0) {
            u32 delta_s = time_ref->tv_host.tv_sec
                        - time_ref->tv_host_0.tv_sec;
            if (delta_s > 4200) {
                time_ref->tv_host_0 = time_ref->tv_host;
                time_ref->ts_total = 0;
            }
        }

        time_ref->tv_host = ktime_to_timeval(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 timeval according to current ts and time_ref data
 */
void peak_usb_get_ts_tv(struct peak_time_ref *time_ref, u32 ts,
            struct timeval *tv)
{
    /* protect from getting timeval before setting now */
    if (time_ref->tv_host.tv_sec > 0) {
        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;

        *tv = time_ref->tv_host_0;
        peak_usb_add_us(tv, (u32)delta_us);
    } else {
        *tv = ktime_to_timeval(ktime_get());
    }
}

/*
 * 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->dlc;

        /* prevent tx timeout */
        netdev->trans_start = jiffies;
        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 can_frame *cf = (struct can_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;
    context->dlc = cf->can_dlc;

    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);
        case -ENOENT:
            /* cable unplugged */
            stats->tx_dropped++;
        }
    } else {
        netdev->trans_start = jiffies;

        /* 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) {
            netdev_err(netdev, "No memory left for URBs\n");
            err = -ENOMEM;
            break;
        }

        buf = kmalloc(dev->adapter->rx_buffer_size, GFP_KERNEL);
        if (!buf) {
            netdev_err(netdev, "No memory left for USB buffer\n");
            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) {
            netdev_err(netdev, "No memory left for URBs\n");
            err = -ENOMEM;
            break;
        }

        buf = kmalloc(dev->adapter->tx_buffer_size, GFP_KERNEL);
        if (!buf) {
            netdev_err(netdev, "No memory left for USB buffer\n");
            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");
            return err;
        }

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

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

    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 failed;
    }

    dev->can.state = CAN_STATE_ERROR_ACTIVE;

    return 0;

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

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

    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;
    }

    dev->open_time = jiffies;
    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);

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

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

    close_candev(netdev);

    dev->open_time = 0;
    dev->can.state = CAN_STATE_STOPPED;

    /* 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) {
        netdev_err(dev->netdev, "no memory left for urb\n");
        return -ENOMEM;
    }

    /* also allocate enough space for the commands to send */
    buf = kmalloc(PCAN_USB_MAX_CMD_LEN, GFP_ATOMIC);
    if (!buf) {
        netdev_err(dev->netdev, "no memory left for async cmd\n");
        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;

    if (!dev->open_time)
        return -EINVAL;

    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 bitrate.
 */
static int peak_usb_set_bittiming(struct net_device *netdev)
{
    struct peak_usb_device *dev = netdev_priv(netdev);
    struct can_bittiming *bt = &dev->can.bittiming;

    if (dev->adapter->dev_set_bittiming) {
        int err = dev->adapter->dev_set_bittiming(dev, bt);

        if (err)
            netdev_info(netdev, "couldn't set 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,
};

/*
 * create one device which is attached to CAN controller #ctrl_idx of the
 * usb adapter.
 */
static int peak_usb_create_dev(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) {
        dev_err(&intf->dev, "%s: couldn't alloc cmd buffer\n",
            PCAN_USB_DRIVER_NAME);
        err = -ENOMEM;
        goto lbl_set_intf_data;
    }

    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.do_set_mode = peak_usb_set_mode;
    dev->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
                      CAN_CTRLMODE_LISTENONLY;

    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);

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

    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_free_cmd_buf;
    }

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

    /* 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_free_cmd_buf:
    kfree(dev->cmd_buf);

lbl_set_intf_data:
    usb_set_intfdata(intf, dev->prev_siblings);
    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;

    /* 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->state &= ~PCAN_USB_STATE_CONNECTED;
        strncpy(name, netdev->name, IFNAMSIZ);

        unregister_netdev(netdev);
        free_candev(netdev);

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

        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);
    struct peak_usb_adapter *peak_usb_adapter, **pp;
    int i, err = -ENOMEM;

    usb_dev = interface_to_usbdev(intf);

    /* get corresponding PCAN-USB adapter */
    for (pp = peak_usb_adapters_list; *pp; pp++)
        if ((*pp)->device_id == usb_dev->descriptor.idProduct)
            break;

    peak_usb_adapter = *pp;
    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_dev->descriptor.idProduct);
        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);