usbatm.c

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/******************************************************************************
 *  usbatm.c - Generic USB xDSL driver core
 *
 *  Copyright (C) 2001, Alcatel
 *  Copyright (C) 2003, Duncan Sands, SolNegro, Josep Comas
 *  Copyright (C) 2004, David Woodhouse, Roman Kagan
 *
 *  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; either version 2 of the License, or (at your option)
 *  any later version.
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License along with
 *  this program; if not, write to the Free Software Foundation, Inc., 59
 *  Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 ******************************************************************************/

/*
 *  Written by Johan Verrept, Duncan Sands ([email protected]) and David Woodhouse
 *
 *  1.7+:   - See the check-in logs
 *
 *  1.6:    - No longer opens a connection if the firmware is not loaded
 *          - Added support for the speedtouch 330
 *          - Removed the limit on the number of devices
 *          - Module now autoloads on device plugin
 *          - Merged relevant parts of sarlib
 *          - Replaced the kernel thread with a tasklet
 *          - New packet transmission code
 *          - Changed proc file contents
 *          - Fixed all known SMP races
 *          - Many fixes and cleanups
 *          - Various fixes by Oliver Neukum ([email protected])
 *
 *  1.5A:   - Version for inclusion in 2.5 series kernel
 *      - Modifications by Richard Purdie ([email protected])
 *      - made compatible with kernel 2.5.6 onwards by changing
 *      usbatm_usb_send_data_context->urb to a pointer and adding code
 *      to alloc and free it
 *      - remove_wait_queue() added to usbatm_atm_processqueue_thread()
 *
 *  1.5:    - fixed memory leak when atmsar_decode_aal5 returned NULL.
 *      (reported by [email protected])
 *
 *  1.4:    - changed the spin_lock() under interrupt to spin_lock_irqsave()
 *      - unlink all active send urbs of a vcc that is being closed.
 *
 *  1.3.1:  - added the version number
 *
 *  1.3:    - Added multiple send urb support
 *      - fixed memory leak and vcc->tx_inuse starvation bug
 *        when not enough memory left in vcc.
 *
 *  1.2:    - Fixed race condition in usbatm_usb_send_data()
 *  1.1:    - Turned off packet debugging
 *
 */

#include "usbatm.h"

#include <asm/uaccess.h>
#include <linux/crc32.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/kthread.h>
#include <linux/ratelimit.h>

#ifdef VERBOSE_DEBUG
static int usbatm_print_packet(struct usbatm_data *instance, const unsigned char *data, int len);
#define PACKETDEBUG(arg...) usbatm_print_packet(arg)
#define vdbg(arg...)        dev_dbg(arg)
#else
#define PACKETDEBUG(arg...)
#define vdbg(arg...)
#endif

#define DRIVER_AUTHOR   "Johan Verrept, Duncan Sands <[email protected]>"
#define DRIVER_VERSION  "1.10"
#define DRIVER_DESC "Generic USB ATM/DSL I/O, version " DRIVER_VERSION

static const char usbatm_driver_name[] = "usbatm";

#define UDSL_MAX_RCV_URBS       16
#define UDSL_MAX_SND_URBS       16
#define UDSL_MAX_BUF_SIZE       65536
#define UDSL_DEFAULT_RCV_URBS       4
#define UDSL_DEFAULT_SND_URBS       4
#define UDSL_DEFAULT_RCV_BUF_SIZE   3392    /* 64 * ATM_CELL_SIZE */
#define UDSL_DEFAULT_SND_BUF_SIZE   3392    /* 64 * ATM_CELL_SIZE */

#define ATM_CELL_HEADER         (ATM_CELL_SIZE - ATM_CELL_PAYLOAD)

#define THROTTLE_MSECS          100 /* delay to recover processing after urb submission fails */

static unsigned int num_rcv_urbs = UDSL_DEFAULT_RCV_URBS;
static unsigned int num_snd_urbs = UDSL_DEFAULT_SND_URBS;
static unsigned int rcv_buf_bytes = UDSL_DEFAULT_RCV_BUF_SIZE;
static unsigned int snd_buf_bytes = UDSL_DEFAULT_SND_BUF_SIZE;

module_param(num_rcv_urbs, uint, S_IRUGO);
MODULE_PARM_DESC(num_rcv_urbs,
         "Number of urbs used for reception (range: 0-"
         __MODULE_STRING(UDSL_MAX_RCV_URBS) ", default: "
         __MODULE_STRING(UDSL_DEFAULT_RCV_URBS) ")");

module_param(num_snd_urbs, uint, S_IRUGO);
MODULE_PARM_DESC(num_snd_urbs,
         "Number of urbs used for transmission (range: 0-"
         __MODULE_STRING(UDSL_MAX_SND_URBS) ", default: "
         __MODULE_STRING(UDSL_DEFAULT_SND_URBS) ")");

module_param(rcv_buf_bytes, uint, S_IRUGO);
MODULE_PARM_DESC(rcv_buf_bytes,
         "Size of the buffers used for reception, in bytes (range: 1-"
         __MODULE_STRING(UDSL_MAX_BUF_SIZE) ", default: "
         __MODULE_STRING(UDSL_DEFAULT_RCV_BUF_SIZE) ")");

module_param(snd_buf_bytes, uint, S_IRUGO);
MODULE_PARM_DESC(snd_buf_bytes,
         "Size of the buffers used for transmission, in bytes (range: 1-"
         __MODULE_STRING(UDSL_MAX_BUF_SIZE) ", default: "
         __MODULE_STRING(UDSL_DEFAULT_SND_BUF_SIZE) ")");


/* receive */

struct usbatm_vcc_data {
    /* vpi/vci lookup */
    struct list_head list;
    short vpi;
    int vci;
    struct atm_vcc *vcc;

    /* raw cell reassembly */
    struct sk_buff *sarb;
};


/* send */

struct usbatm_control {
    struct atm_skb_data atm;
    u32 len;
    u32 crc;
};

#define UDSL_SKB(x)     ((struct usbatm_control *)(x)->cb)


/* ATM */

static void usbatm_atm_dev_close(struct atm_dev *atm_dev);
static int usbatm_atm_open(struct atm_vcc *vcc);
static void usbatm_atm_close(struct atm_vcc *vcc);
static int usbatm_atm_ioctl(struct atm_dev *atm_dev, unsigned int cmd, void __user * arg);
static int usbatm_atm_send(struct atm_vcc *vcc, struct sk_buff *skb);
static int usbatm_atm_proc_read(struct atm_dev *atm_dev, loff_t * pos, char *page);

static struct atmdev_ops usbatm_atm_devops = {
    .dev_close  = usbatm_atm_dev_close,
    .open       = usbatm_atm_open,
    .close      = usbatm_atm_close,
    .ioctl      = usbatm_atm_ioctl,
    .send       = usbatm_atm_send,
    .proc_read  = usbatm_atm_proc_read,
    .owner      = THIS_MODULE,
};


/***********
**  misc  **
***********/

static inline unsigned int usbatm_pdu_length(unsigned int length)
{
    length += ATM_CELL_PAYLOAD - 1 + ATM_AAL5_TRAILER;
    return length - length % ATM_CELL_PAYLOAD;
}

static inline void usbatm_pop(struct atm_vcc *vcc, struct sk_buff *skb)
{
    if (vcc->pop)
        vcc->pop(vcc, skb);
    else
        dev_kfree_skb_any(skb);
}


/***********
**  urbs  **
************/

static struct urb *usbatm_pop_urb(struct usbatm_channel *channel)
{
    struct urb *urb;

    spin_lock_irq(&channel->lock);
    if (list_empty(&channel->list)) {
        spin_unlock_irq(&channel->lock);
        return NULL;
    }

    urb = list_entry(channel->list.next, struct urb, urb_list);
    list_del(&urb->urb_list);
    spin_unlock_irq(&channel->lock);

    return urb;
}

static int usbatm_submit_urb(struct urb *urb)
{
    struct usbatm_channel *channel = urb->context;
    int ret;

    /* vdbg("%s: submitting urb 0x%p, size %u",
         __func__, urb, urb->transfer_buffer_length); */

    ret = usb_submit_urb(urb, GFP_ATOMIC);
    if (ret) {
        if (printk_ratelimit())
            atm_warn(channel->usbatm, "%s: urb 0x%p submission failed (%d)!\n",
                __func__, urb, ret);

        /* consider all errors transient and return the buffer back to the queue */
        urb->status = -EAGAIN;
        spin_lock_irq(&channel->lock);

        /* must add to the front when sending; doesn't matter when receiving */
        list_add(&urb->urb_list, &channel->list);

        spin_unlock_irq(&channel->lock);

        /* make sure the channel doesn't stall */
        mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
    }

    return ret;
}

static void usbatm_complete(struct urb *urb)
{
    struct usbatm_channel *channel = urb->context;
    unsigned long flags;
    int status = urb->status;

    /* vdbg("%s: urb 0x%p, status %d, actual_length %d",
         __func__, urb, status, urb->actual_length); */

    /* usually in_interrupt(), but not always */
    spin_lock_irqsave(&channel->lock, flags);

    /* must add to the back when receiving; doesn't matter when sending */
    list_add_tail(&urb->urb_list, &channel->list);

    spin_unlock_irqrestore(&channel->lock, flags);

    if (unlikely(status) &&
            (!(channel->usbatm->flags & UDSL_IGNORE_EILSEQ) ||
             status != -EILSEQ)) {
        if (status == -ESHUTDOWN)
            return;

        if (printk_ratelimit())
            atm_warn(channel->usbatm, "%s: urb 0x%p failed (%d)!\n",
                __func__, urb, status);
        /* throttle processing in case of an error */
        mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
    } else
        tasklet_schedule(&channel->tasklet);
}


/*************
**  decode  **
*************/

static inline struct usbatm_vcc_data *usbatm_find_vcc(struct usbatm_data *instance,
                          short vpi, int vci)
{
    struct usbatm_vcc_data *vcc_data;

    list_for_each_entry(vcc_data, &instance->vcc_list, list)
        if ((vcc_data->vci == vci) && (vcc_data->vpi == vpi))
            return vcc_data;
    return NULL;
}

static void usbatm_extract_one_cell(struct usbatm_data *instance, unsigned char *source)
{
    struct atm_vcc *vcc;
    struct sk_buff *sarb;
    short vpi = ((source[0] & 0x0f) << 4)  | (source[1] >> 4);
    int vci = ((source[1] & 0x0f) << 12) | (source[2] << 4) | (source[3] >> 4);
    u8 pti = ((source[3] & 0xe) >> 1);

    vdbg(&instance->usb_intf->dev, "%s: vpi %hd, vci %d, pti %d", __func__, vpi, vci, pti);

    if ((vci != instance->cached_vci) || (vpi != instance->cached_vpi)) {
        instance->cached_vpi = vpi;
        instance->cached_vci = vci;

        instance->cached_vcc = usbatm_find_vcc(instance, vpi, vci);

        if (!instance->cached_vcc)
            atm_rldbg(instance, "%s: unknown vpi/vci (%hd/%d)!\n", __func__, vpi, vci);
    }

    if (!instance->cached_vcc)
        return;

    vcc = instance->cached_vcc->vcc;

    /* OAM F5 end-to-end */
    if (pti == ATM_PTI_E2EF5) {
        if (printk_ratelimit())
            atm_warn(instance, "%s: OAM not supported (vpi %d, vci %d)!\n",
                __func__, vpi, vci);
        atomic_inc(&vcc->stats->rx_err);
        return;
    }

    sarb = instance->cached_vcc->sarb;

    if (sarb->tail + ATM_CELL_PAYLOAD > sarb->end) {
        atm_rldbg(instance, "%s: buffer overrun (sarb->len %u, vcc: 0x%p)!\n",
                __func__, sarb->len, vcc);
        /* discard cells already received */
        skb_trim(sarb, 0);
        UDSL_ASSERT(instance, sarb->tail + ATM_CELL_PAYLOAD <= sarb->end);
    }

    memcpy(skb_tail_pointer(sarb), source + ATM_CELL_HEADER, ATM_CELL_PAYLOAD);
    __skb_put(sarb, ATM_CELL_PAYLOAD);

    if (pti & 1) {
        struct sk_buff *skb;
        unsigned int length;
        unsigned int pdu_length;

        length = (source[ATM_CELL_SIZE - 6] << 8) + source[ATM_CELL_SIZE - 5];

        /* guard against overflow */
        if (length > ATM_MAX_AAL5_PDU) {
            atm_rldbg(instance, "%s: bogus length %u (vcc: 0x%p)!\n",
                  __func__, length, vcc);
            atomic_inc(&vcc->stats->rx_err);
            goto out;
        }

        pdu_length = usbatm_pdu_length(length);

        if (sarb->len < pdu_length) {
            atm_rldbg(instance, "%s: bogus pdu_length %u (sarb->len: %u, vcc: 0x%p)!\n",
                  __func__, pdu_length, sarb->len, vcc);
            atomic_inc(&vcc->stats->rx_err);
            goto out;
        }

        if (crc32_be(~0, skb_tail_pointer(sarb) - pdu_length, pdu_length) != 0xc704dd7b) {
            atm_rldbg(instance, "%s: packet failed crc check (vcc: 0x%p)!\n",
                  __func__, vcc);
            atomic_inc(&vcc->stats->rx_err);
            goto out;
        }

        vdbg(&instance->usb_intf->dev,
             "%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)",
             __func__, length, pdu_length, vcc);

        if (!(skb = dev_alloc_skb(length))) {
            if (printk_ratelimit())
                atm_err(instance, "%s: no memory for skb (length: %u)!\n",
                    __func__, length);
            atomic_inc(&vcc->stats->rx_drop);
            goto out;
        }

        vdbg(&instance->usb_intf->dev,
             "%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)",
             __func__, skb, skb->truesize);

        if (!atm_charge(vcc, skb->truesize)) {
            atm_rldbg(instance, "%s: failed atm_charge (skb->truesize: %u)!\n",
                  __func__, skb->truesize);
            dev_kfree_skb_any(skb);
            goto out;   /* atm_charge increments rx_drop */
        }

        skb_copy_to_linear_data(skb,
                    skb_tail_pointer(sarb) - pdu_length,
                    length);
        __skb_put(skb, length);

        vdbg(&instance->usb_intf->dev,
             "%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
             __func__, skb, skb->len, skb->truesize);

        PACKETDEBUG(instance, skb->data, skb->len);

        vcc->push(vcc, skb);

        atomic_inc(&vcc->stats->rx);
    out:
        skb_trim(sarb, 0);
    }
}

static void usbatm_extract_cells(struct usbatm_data *instance,
        unsigned char *source, unsigned int avail_data)
{
    unsigned int stride = instance->rx_channel.stride;
    unsigned int buf_usage = instance->buf_usage;

    /* extract cells from incoming data, taking into account that
     * the length of avail data may not be a multiple of stride */

    if (buf_usage > 0) {
        /* we have a partially received atm cell */
        unsigned char *cell_buf = instance->cell_buf;
        unsigned int space_left = stride - buf_usage;

        UDSL_ASSERT(instance, buf_usage <= stride);

        if (avail_data >= space_left) {
            /* add new data and process cell */
            memcpy(cell_buf + buf_usage, source, space_left);
            source += space_left;
            avail_data -= space_left;
            usbatm_extract_one_cell(instance, cell_buf);
            instance->buf_usage = 0;
        } else {
            /* not enough data to fill the cell */
            memcpy(cell_buf + buf_usage, source, avail_data);
            instance->buf_usage = buf_usage + avail_data;
            return;
        }
    }

    for (; avail_data >= stride; avail_data -= stride, source += stride)
        usbatm_extract_one_cell(instance, source);

    if (avail_data > 0) {
        /* length was not a multiple of stride -
         * save remaining data for next call */
        memcpy(instance->cell_buf, source, avail_data);
        instance->buf_usage = avail_data;
    }
}


/*************
**  encode  **
*************/

static unsigned int usbatm_write_cells(struct usbatm_data *instance,
                       struct sk_buff *skb,
                       u8 *target, unsigned int avail_space)
{
    struct usbatm_control *ctrl = UDSL_SKB(skb);
    struct atm_vcc *vcc = ctrl->atm.vcc;
    unsigned int bytes_written;
    unsigned int stride = instance->tx_channel.stride;

    vdbg(&instance->usb_intf->dev, "%s: skb->len=%d, avail_space=%u",
         __func__, skb->len, avail_space);
    UDSL_ASSERT(instance, !(avail_space % stride));

    for (bytes_written = 0; bytes_written < avail_space && ctrl->len;
         bytes_written += stride, target += stride) {
        unsigned int data_len = min_t(unsigned int, skb->len, ATM_CELL_PAYLOAD);
        unsigned int left = ATM_CELL_PAYLOAD - data_len;
        u8 *ptr = target;

        ptr[0] = vcc->vpi >> 4;
        ptr[1] = (vcc->vpi << 4) | (vcc->vci >> 12);
        ptr[2] = vcc->vci >> 4;
        ptr[3] = vcc->vci << 4;
        ptr[4] = 0xec;
        ptr += ATM_CELL_HEADER;

        skb_copy_from_linear_data(skb, ptr, data_len);
        ptr += data_len;
        __skb_pull(skb, data_len);

        if (!left)
            continue;

        memset(ptr, 0, left);

        if (left >= ATM_AAL5_TRAILER) { /* trailer will go in this cell */
            u8 *trailer = target + ATM_CELL_SIZE - ATM_AAL5_TRAILER;
            /* trailer[0] = 0;      UU = 0 */
            /* trailer[1] = 0;      CPI = 0 */
            trailer[2] = ctrl->len >> 8;
            trailer[3] = ctrl->len;

            ctrl->crc = ~crc32_be(ctrl->crc, ptr, left - 4);

            trailer[4] = ctrl->crc >> 24;
            trailer[5] = ctrl->crc >> 16;
            trailer[6] = ctrl->crc >> 8;
            trailer[7] = ctrl->crc;

            target[3] |= 0x2;   /* adjust PTI */

            ctrl->len = 0;      /* tag this skb finished */
        } else
            ctrl->crc = crc32_be(ctrl->crc, ptr, left);
    }

    return bytes_written;
}


/**************
**  receive  **
**************/

static void usbatm_rx_process(unsigned long data)
{
    struct usbatm_data *instance = (struct usbatm_data *)data;
    struct urb *urb;

    while ((urb = usbatm_pop_urb(&instance->rx_channel))) {
        vdbg(&instance->usb_intf->dev,
             "%s: processing urb 0x%p", __func__, urb);

        if (usb_pipeisoc(urb->pipe)) {
            unsigned char *merge_start = NULL;
            unsigned int merge_length = 0;
            const unsigned int packet_size = instance->rx_channel.packet_size;
            int i;

            for (i = 0; i < urb->number_of_packets; i++) {
                if (!urb->iso_frame_desc[i].status) {
                    unsigned int actual_length = urb->iso_frame_desc[i].actual_length;

                    UDSL_ASSERT(instance, actual_length <= packet_size);

                    if (!merge_length)
                        merge_start = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
                    merge_length += actual_length;
                    if (merge_length && (actual_length < packet_size)) {
                        usbatm_extract_cells(instance, merge_start, merge_length);
                        merge_length = 0;
                    }
                } else {
                    atm_rldbg(instance, "%s: status %d in frame %d!\n", __func__, urb->status, i);
                    if (merge_length)
                        usbatm_extract_cells(instance, merge_start, merge_length);
                    merge_length = 0;
                    instance->buf_usage = 0;
                }
            }

            if (merge_length)
                usbatm_extract_cells(instance, merge_start, merge_length);
        } else
            if (!urb->status)
                usbatm_extract_cells(instance, urb->transfer_buffer, urb->actual_length);
            else
                instance->buf_usage = 0;

        if (usbatm_submit_urb(urb))
            return;
    }
}


/***********
**  send  **
***********/

static void usbatm_tx_process(unsigned long data)
{
    struct usbatm_data *instance = (struct usbatm_data *)data;
    struct sk_buff *skb = instance->current_skb;
    struct urb *urb = NULL;
    const unsigned int buf_size = instance->tx_channel.buf_size;
    unsigned int bytes_written = 0;
    u8 *buffer = NULL;

    if (!skb)
        skb = skb_dequeue(&instance->sndqueue);

    while (skb) {
        if (!urb) {
            urb = usbatm_pop_urb(&instance->tx_channel);
            if (!urb)
                break;      /* no more senders */
            buffer = urb->transfer_buffer;
            bytes_written = (urb->status == -EAGAIN) ?
                urb->transfer_buffer_length : 0;
        }

        bytes_written += usbatm_write_cells(instance, skb,
                          buffer + bytes_written,
                          buf_size - bytes_written);

        vdbg(&instance->usb_intf->dev,
             "%s: wrote %u bytes from skb 0x%p to urb 0x%p",
             __func__, bytes_written, skb, urb);

        if (!UDSL_SKB(skb)->len) {
            struct atm_vcc *vcc = UDSL_SKB(skb)->atm.vcc;

            usbatm_pop(vcc, skb);
            atomic_inc(&vcc->stats->tx);

            skb = skb_dequeue(&instance->sndqueue);
        }

        if (bytes_written == buf_size || (!skb && bytes_written)) {
            urb->transfer_buffer_length = bytes_written;

            if (usbatm_submit_urb(urb))
                break;
            urb = NULL;
        }
    }

    instance->current_skb = skb;
}

static void usbatm_cancel_send(struct usbatm_data *instance,
                   struct atm_vcc *vcc)
{
    struct sk_buff *skb, *n;

    atm_dbg(instance, "%s entered\n", __func__);
    spin_lock_irq(&instance->sndqueue.lock);
    skb_queue_walk_safe(&instance->sndqueue, skb, n) {
        if (UDSL_SKB(skb)->atm.vcc == vcc) {
            atm_dbg(instance, "%s: popping skb 0x%p\n", __func__, skb);
            __skb_unlink(skb, &instance->sndqueue);
            usbatm_pop(vcc, skb);
        }
    }
    spin_unlock_irq(&instance->sndqueue.lock);

    tasklet_disable(&instance->tx_channel.tasklet);
    if ((skb = instance->current_skb) && (UDSL_SKB(skb)->atm.vcc == vcc)) {
        atm_dbg(instance, "%s: popping current skb (0x%p)\n", __func__, skb);
        instance->current_skb = NULL;
        usbatm_pop(vcc, skb);
    }
    tasklet_enable(&instance->tx_channel.tasklet);
    atm_dbg(instance, "%s done\n", __func__);
}

static int usbatm_atm_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
    struct usbatm_data *instance = vcc->dev->dev_data;
    struct usbatm_control *ctrl = UDSL_SKB(skb);
    int err;

    vdbg(&instance->usb_intf->dev, "%s called (skb 0x%p, len %u)", __func__,
         skb, skb->len);

    /* racy disconnection check - fine */
    if (!instance || instance->disconnected) {
#ifdef DEBUG
        printk_ratelimited(KERN_DEBUG "%s: %s!\n", __func__, instance ? "disconnected" : "NULL instance");
#endif
        err = -ENODEV;
        goto fail;
    }

    if (vcc->qos.aal != ATM_AAL5) {
        atm_rldbg(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
        err = -EINVAL;
        goto fail;
    }

    if (skb->len > ATM_MAX_AAL5_PDU) {
        atm_rldbg(instance, "%s: packet too long (%d vs %d)!\n",
                __func__, skb->len, ATM_MAX_AAL5_PDU);
        err = -EINVAL;
        goto fail;
    }

    PACKETDEBUG(instance, skb->data, skb->len);

    /* initialize the control block */
    ctrl->atm.vcc = vcc;
    ctrl->len = skb->len;
    ctrl->crc = crc32_be(~0, skb->data, skb->len);

    skb_queue_tail(&instance->sndqueue, skb);
    tasklet_schedule(&instance->tx_channel.tasklet);

    return 0;

 fail:
    usbatm_pop(vcc, skb);
    return err;
}


/********************
**  bean counting  **
********************/

static void usbatm_destroy_instance(struct kref *kref)
{
    struct usbatm_data *instance = container_of(kref, struct usbatm_data, refcount);

    usb_dbg(instance, "%s\n", __func__);

    tasklet_kill(&instance->rx_channel.tasklet);
    tasklet_kill(&instance->tx_channel.tasklet);
    usb_put_dev(instance->usb_dev);
    kfree(instance);
}

static void usbatm_get_instance(struct usbatm_data *instance)
{
    usb_dbg(instance, "%s\n", __func__);

    kref_get(&instance->refcount);
}

static void usbatm_put_instance(struct usbatm_data *instance)
{
    usb_dbg(instance, "%s\n", __func__);

    kref_put(&instance->refcount, usbatm_destroy_instance);
}


/**********
**  ATM  **
**********/

static void usbatm_atm_dev_close(struct atm_dev *atm_dev)
{
    struct usbatm_data *instance = atm_dev->dev_data;

    if (!instance)
        return;

    usb_dbg(instance, "%s\n", __func__);
    atm_dev->dev_data = NULL; /* catch bugs */
    usbatm_put_instance(instance);  /* taken in usbatm_atm_init */
}

static int usbatm_atm_proc_read(struct atm_dev *atm_dev, loff_t * pos, char *page)
{
    struct usbatm_data *instance = atm_dev->dev_data;
    int left = *pos;

    if (!instance)
        return -ENODEV;

    if (!left--)
        return sprintf(page, "%s\n", instance->description);

    if (!left--)
        return sprintf(page, "MAC: %pM\n", atm_dev->esi);

    if (!left--)
        return sprintf(page,
                   "AAL5: tx %d ( %d err ), rx %d ( %d err, %d drop )\n",
                   atomic_read(&atm_dev->stats.aal5.tx),
                   atomic_read(&atm_dev->stats.aal5.tx_err),
                   atomic_read(&atm_dev->stats.aal5.rx),
                   atomic_read(&atm_dev->stats.aal5.rx_err),
                   atomic_read(&atm_dev->stats.aal5.rx_drop));

    if (!left--) {
        if (instance->disconnected)
            return sprintf(page, "Disconnected\n");
        else
            switch (atm_dev->signal) {
            case ATM_PHY_SIG_FOUND:
                return sprintf(page, "Line up\n");
            case ATM_PHY_SIG_LOST:
                return sprintf(page, "Line down\n");
            default:
                return sprintf(page, "Line state unknown\n");
            }
    }

    return 0;
}

static int usbatm_atm_open(struct atm_vcc *vcc)
{
    struct usbatm_data *instance = vcc->dev->dev_data;
    struct usbatm_vcc_data *new = NULL;
    int ret;
    int vci = vcc->vci;
    short vpi = vcc->vpi;

    if (!instance)
        return -ENODEV;

    atm_dbg(instance, "%s: vpi %hd, vci %d\n", __func__, vpi, vci);

    /* only support AAL5 */
    if ((vcc->qos.aal != ATM_AAL5)) {
        atm_warn(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
        return -EINVAL;
    }

    /* sanity checks */
    if ((vcc->qos.rxtp.max_sdu < 0) || (vcc->qos.rxtp.max_sdu > ATM_MAX_AAL5_PDU)) {
        atm_dbg(instance, "%s: max_sdu %d out of range!\n", __func__, vcc->qos.rxtp.max_sdu);
        return -EINVAL;
    }

    mutex_lock(&instance->serialize);   /* vs self, usbatm_atm_close, usbatm_usb_disconnect */

    if (instance->disconnected) {
        atm_dbg(instance, "%s: disconnected!\n", __func__);
        ret = -ENODEV;
        goto fail;
    }

    if (usbatm_find_vcc(instance, vpi, vci)) {
        atm_dbg(instance, "%s: %hd/%d already in use!\n", __func__, vpi, vci);
        ret = -EADDRINUSE;
        goto fail;
    }

    if (!(new = kzalloc(sizeof(struct usbatm_vcc_data), GFP_KERNEL))) {
        atm_err(instance, "%s: no memory for vcc_data!\n", __func__);
        ret = -ENOMEM;
        goto fail;
    }

    new->vcc = vcc;
    new->vpi = vpi;
    new->vci = vci;

    new->sarb = alloc_skb(usbatm_pdu_length(vcc->qos.rxtp.max_sdu), GFP_KERNEL);
    if (!new->sarb) {
        atm_err(instance, "%s: no memory for SAR buffer!\n", __func__);
        ret = -ENOMEM;
        goto fail;
    }

    vcc->dev_data = new;

    tasklet_disable(&instance->rx_channel.tasklet);
    instance->cached_vcc = new;
    instance->cached_vpi = vpi;
    instance->cached_vci = vci;
    list_add(&new->list, &instance->vcc_list);
    tasklet_enable(&instance->rx_channel.tasklet);

    set_bit(ATM_VF_ADDR, &vcc->flags);
    set_bit(ATM_VF_PARTIAL, &vcc->flags);
    set_bit(ATM_VF_READY, &vcc->flags);

    mutex_unlock(&instance->serialize);

    atm_dbg(instance, "%s: allocated vcc data 0x%p\n", __func__, new);

    return 0;

fail:
    kfree(new);
    mutex_unlock(&instance->serialize);
    return ret;
}

static void usbatm_atm_close(struct atm_vcc *vcc)
{
    struct usbatm_data *instance = vcc->dev->dev_data;
    struct usbatm_vcc_data *vcc_data = vcc->dev_data;

    if (!instance || !vcc_data)
        return;

    atm_dbg(instance, "%s entered\n", __func__);

    atm_dbg(instance, "%s: deallocating vcc 0x%p with vpi %d vci %d\n",
        __func__, vcc_data, vcc_data->vpi, vcc_data->vci);

    usbatm_cancel_send(instance, vcc);

    mutex_lock(&instance->serialize);   /* vs self, usbatm_atm_open, usbatm_usb_disconnect */

    tasklet_disable(&instance->rx_channel.tasklet);
    if (instance->cached_vcc == vcc_data) {
        instance->cached_vcc = NULL;
        instance->cached_vpi = ATM_VPI_UNSPEC;
        instance->cached_vci = ATM_VCI_UNSPEC;
    }
    list_del(&vcc_data->list);
    tasklet_enable(&instance->rx_channel.tasklet);

    kfree_skb(vcc_data->sarb);
    vcc_data->sarb = NULL;

    kfree(vcc_data);
    vcc->dev_data = NULL;

    vcc->vpi = ATM_VPI_UNSPEC;
    vcc->vci = ATM_VCI_UNSPEC;
    clear_bit(ATM_VF_READY, &vcc->flags);
    clear_bit(ATM_VF_PARTIAL, &vcc->flags);
    clear_bit(ATM_VF_ADDR, &vcc->flags);

    mutex_unlock(&instance->serialize);

    atm_dbg(instance, "%s successful\n", __func__);
}

static int usbatm_atm_ioctl(struct atm_dev *atm_dev, unsigned int cmd,
              void __user * arg)
{
    struct usbatm_data *instance = atm_dev->dev_data;

    if (!instance || instance->disconnected)
        return -ENODEV;

    switch (cmd) {
    case ATM_QUERYLOOP:
        return put_user(ATM_LM_NONE, (int __user *)arg) ? -EFAULT : 0;
    default:
        return -ENOIOCTLCMD;
    }
}

static int usbatm_atm_init(struct usbatm_data *instance)
{
    struct atm_dev *atm_dev;
    int ret, i;

    /* ATM init.  The ATM initialization scheme suffers from an intrinsic race
     * condition: callbacks we register can be executed at once, before we have
     * initialized the struct atm_dev.  To protect against this, all callbacks
     * abort if atm_dev->dev_data is NULL. */
    atm_dev = atm_dev_register(instance->driver_name,
                   &instance->usb_intf->dev, &usbatm_atm_devops,
                   -1, NULL);
    if (!atm_dev) {
        usb_err(instance, "%s: failed to register ATM device!\n", __func__);
        return -1;
    }

    instance->atm_dev = atm_dev;

    atm_dev->ci_range.vpi_bits = ATM_CI_MAX;
    atm_dev->ci_range.vci_bits = ATM_CI_MAX;
    atm_dev->signal = ATM_PHY_SIG_UNKNOWN;

    /* temp init ATM device, set to 128kbit */
    atm_dev->link_rate = 128 * 1000 / 424;

    if (instance->driver->atm_start && ((ret = instance->driver->atm_start(instance, atm_dev)) < 0)) {
        atm_err(instance, "%s: atm_start failed: %d!\n", __func__, ret);
        goto fail;
    }

    usbatm_get_instance(instance);  /* dropped in usbatm_atm_dev_close */

    /* ready for ATM callbacks */
    mb();
    atm_dev->dev_data = instance;

    /* submit all rx URBs */
    for (i = 0; i < num_rcv_urbs; i++)
        usbatm_submit_urb(instance->urbs[i]);

    return 0;

 fail:
    instance->atm_dev = NULL;
    atm_dev_deregister(atm_dev); /* usbatm_atm_dev_close will eventually be called */
    return ret;
}


/**********
**  USB  **
**********/

static int usbatm_do_heavy_init(void *arg)
{
    struct usbatm_data *instance = arg;
    int ret;

    allow_signal(SIGTERM);
    complete(&instance->thread_started);

    ret = instance->driver->heavy_init(instance, instance->usb_intf);

    if (!ret)
        ret = usbatm_atm_init(instance);

    mutex_lock(&instance->serialize);
    instance->thread = NULL;
    mutex_unlock(&instance->serialize);

    complete_and_exit(&instance->thread_exited, ret);
}

static int usbatm_heavy_init(struct usbatm_data *instance)
{
    struct task_struct *t;

    t = kthread_create(usbatm_do_heavy_init, instance,
            instance->driver->driver_name);
    if (IS_ERR(t)) {
        usb_err(instance, "%s: failed to create kernel_thread (%ld)!\n",
                __func__, PTR_ERR(t));
        return PTR_ERR(t);
    }

    instance->thread = t;
    wake_up_process(t);
    wait_for_completion(&instance->thread_started);

    return 0;
}

static void usbatm_tasklet_schedule(unsigned long data)
{
    tasklet_schedule((struct tasklet_struct *) data);
}

static void usbatm_init_channel(struct usbatm_channel *channel)
{
    spin_lock_init(&channel->lock);
    INIT_LIST_HEAD(&channel->list);
    channel->delay.function = usbatm_tasklet_schedule;
    channel->delay.data = (unsigned long) &channel->tasklet;
    init_timer(&channel->delay);
}

int usbatm_usb_probe(struct usb_interface *intf, const struct usb_device_id *id,
             struct usbatm_driver *driver)
{
    struct device *dev = &intf->dev;
    struct usb_device *usb_dev = interface_to_usbdev(intf);
    struct usbatm_data *instance;
    char *buf;
    int error = -ENOMEM;
    int i, length;
    unsigned int maxpacket, num_packets;

    dev_dbg(dev, "%s: trying driver %s with vendor=%04x, product=%04x, ifnum %2d\n",
            __func__, driver->driver_name,
            le16_to_cpu(usb_dev->descriptor.idVendor),
            le16_to_cpu(usb_dev->descriptor.idProduct),
            intf->altsetting->desc.bInterfaceNumber);

    /* instance init */
    instance = kzalloc(sizeof(*instance) + sizeof(struct urb *) * (num_rcv_urbs + num_snd_urbs), GFP_KERNEL);
    if (!instance) {
        dev_err(dev, "%s: no memory for instance data!\n", __func__);
        return -ENOMEM;
    }

    /* public fields */

    instance->driver = driver;
    snprintf(instance->driver_name, sizeof(instance->driver_name), driver->driver_name);

    instance->usb_dev = usb_dev;
    instance->usb_intf = intf;

    buf = instance->description;
    length = sizeof(instance->description);

    if ((i = usb_string(usb_dev, usb_dev->descriptor.iProduct, buf, length)) < 0)
        goto bind;

    buf += i;
    length -= i;

    i = scnprintf(buf, length, " (");
    buf += i;
    length -= i;

    if (length <= 0 || (i = usb_make_path(usb_dev, buf, length)) < 0)
        goto bind;

    buf += i;
    length -= i;

    snprintf(buf, length, ")");

 bind:
    if (driver->bind && (error = driver->bind(instance, intf, id)) < 0) {
            dev_err(dev, "%s: bind failed: %d!\n", __func__, error);
            goto fail_free;
    }

    /* private fields */

    kref_init(&instance->refcount);     /* dropped in usbatm_usb_disconnect */
    mutex_init(&instance->serialize);

    instance->thread = NULL;
    init_completion(&instance->thread_started);
    init_completion(&instance->thread_exited);

    INIT_LIST_HEAD(&instance->vcc_list);
    skb_queue_head_init(&instance->sndqueue);

    usbatm_init_channel(&instance->rx_channel);
    usbatm_init_channel(&instance->tx_channel);
    tasklet_init(&instance->rx_channel.tasklet, usbatm_rx_process, (unsigned long)instance);
    tasklet_init(&instance->tx_channel.tasklet, usbatm_tx_process, (unsigned long)instance);
    instance->rx_channel.stride = ATM_CELL_SIZE + driver->rx_padding;
    instance->tx_channel.stride = ATM_CELL_SIZE + driver->tx_padding;
    instance->rx_channel.usbatm = instance->tx_channel.usbatm = instance;

    if ((instance->flags & UDSL_USE_ISOC) && driver->isoc_in)
        instance->rx_channel.endpoint = usb_rcvisocpipe(usb_dev, driver->isoc_in);
    else
        instance->rx_channel.endpoint = usb_rcvbulkpipe(usb_dev, driver->bulk_in);

    instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->bulk_out);

    /* tx buffer size must be a positive multiple of the stride */
    instance->tx_channel.buf_size = max(instance->tx_channel.stride,
            snd_buf_bytes - (snd_buf_bytes % instance->tx_channel.stride));

    /* rx buffer size must be a positive multiple of the endpoint maxpacket */
    maxpacket = usb_maxpacket(usb_dev, instance->rx_channel.endpoint, 0);

    if ((maxpacket < 1) || (maxpacket > UDSL_MAX_BUF_SIZE)) {
        dev_err(dev, "%s: invalid endpoint %02x!\n", __func__,
                usb_pipeendpoint(instance->rx_channel.endpoint));
        error = -EINVAL;
        goto fail_unbind;
    }

    num_packets = max(1U, (rcv_buf_bytes + maxpacket / 2) / maxpacket); /* round */

    if (num_packets * maxpacket > UDSL_MAX_BUF_SIZE)
        num_packets--;

    instance->rx_channel.buf_size = num_packets * maxpacket;
    instance->rx_channel.packet_size = maxpacket;

#ifdef DEBUG
    for (i = 0; i < 2; i++) {
        struct usbatm_channel *channel = i ?
            &instance->tx_channel : &instance->rx_channel;

        dev_dbg(dev, "%s: using %d byte buffer for %s channel 0x%p\n", __func__, channel->buf_size, i ? "tx" : "rx", channel);
    }
#endif

    /* initialize urbs */

    for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
        u8 *buffer;
        struct usbatm_channel *channel = i < num_rcv_urbs ?
            &instance->rx_channel : &instance->tx_channel;
        struct urb *urb;
        unsigned int iso_packets = usb_pipeisoc(channel->endpoint) ? channel->buf_size / channel->packet_size : 0;

        UDSL_ASSERT(instance, !usb_pipeisoc(channel->endpoint) || usb_pipein(channel->endpoint));

        urb = usb_alloc_urb(iso_packets, GFP_KERNEL);
        if (!urb) {
            dev_err(dev, "%s: no memory for urb %d!\n", __func__, i);
            error = -ENOMEM;
            goto fail_unbind;
        }

        instance->urbs[i] = urb;

        /* zero the tx padding to avoid leaking information */
        buffer = kzalloc(channel->buf_size, GFP_KERNEL);
        if (!buffer) {
            dev_err(dev, "%s: no memory for buffer %d!\n", __func__, i);
            error = -ENOMEM;
            goto fail_unbind;
        }

        usb_fill_bulk_urb(urb, instance->usb_dev, channel->endpoint,
                  buffer, channel->buf_size, usbatm_complete, channel);
        if (iso_packets) {
            int j;
            urb->interval = 1;
            urb->transfer_flags = URB_ISO_ASAP;
            urb->number_of_packets = iso_packets;
            for (j = 0; j < iso_packets; j++) {
                urb->iso_frame_desc[j].offset = channel->packet_size * j;
                urb->iso_frame_desc[j].length = channel->packet_size;
            }
        }

        /* put all tx URBs on the list of spares */
        if (i >= num_rcv_urbs)
            list_add_tail(&urb->urb_list, &channel->list);

        vdbg(&intf->dev, "%s: alloced buffer 0x%p buf size %u urb 0x%p",
             __func__, urb->transfer_buffer, urb->transfer_buffer_length, urb);
    }

    instance->cached_vpi = ATM_VPI_UNSPEC;
    instance->cached_vci = ATM_VCI_UNSPEC;
    instance->cell_buf = kmalloc(instance->rx_channel.stride, GFP_KERNEL);

    if (!instance->cell_buf) {
        dev_err(dev, "%s: no memory for cell buffer!\n", __func__);
        error = -ENOMEM;
        goto fail_unbind;
    }

    if (!(instance->flags & UDSL_SKIP_HEAVY_INIT) && driver->heavy_init) {
        error = usbatm_heavy_init(instance);
    } else {
        complete(&instance->thread_exited); /* pretend that heavy_init was run */
        error = usbatm_atm_init(instance);
    }

    if (error < 0)
        goto fail_unbind;

    usb_get_dev(usb_dev);
    usb_set_intfdata(intf, instance);

    return 0;

 fail_unbind:
    if (instance->driver->unbind)
        instance->driver->unbind(instance, intf);
 fail_free:
    kfree(instance->cell_buf);

    for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
        if (instance->urbs[i])
            kfree(instance->urbs[i]->transfer_buffer);
        usb_free_urb(instance->urbs[i]);
    }

    kfree(instance);

    return error;
}
EXPORT_SYMBOL_GPL(usbatm_usb_probe);

void usbatm_usb_disconnect(struct usb_interface *intf)
{
    struct device *dev = &intf->dev;
    struct usbatm_data *instance = usb_get_intfdata(intf);
    struct usbatm_vcc_data *vcc_data;
    int i;

    dev_dbg(dev, "%s entered\n", __func__);

    if (!instance) {
        dev_dbg(dev, "%s: NULL instance!\n", __func__);
        return;
    }

    usb_set_intfdata(intf, NULL);

    mutex_lock(&instance->serialize);
    instance->disconnected = 1;
    if (instance->thread != NULL)
        send_sig(SIGTERM, instance->thread, 1);
    mutex_unlock(&instance->serialize);

    wait_for_completion(&instance->thread_exited);

    mutex_lock(&instance->serialize);
    list_for_each_entry(vcc_data, &instance->vcc_list, list)
        vcc_release_async(vcc_data->vcc, -EPIPE);
    mutex_unlock(&instance->serialize);

    tasklet_disable(&instance->rx_channel.tasklet);
    tasklet_disable(&instance->tx_channel.tasklet);

    for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++)
        usb_kill_urb(instance->urbs[i]);

    del_timer_sync(&instance->rx_channel.delay);
    del_timer_sync(&instance->tx_channel.delay);

    /* turn usbatm_[rt]x_process into something close to a no-op */
    /* no need to take the spinlock */
    INIT_LIST_HEAD(&instance->rx_channel.list);
    INIT_LIST_HEAD(&instance->tx_channel.list);

    tasklet_enable(&instance->rx_channel.tasklet);
    tasklet_enable(&instance->tx_channel.tasklet);

    if (instance->atm_dev && instance->driver->atm_stop)
        instance->driver->atm_stop(instance, instance->atm_dev);

    if (instance->driver->unbind)
        instance->driver->unbind(instance, intf);

    instance->driver_data = NULL;

    for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
        kfree(instance->urbs[i]->transfer_buffer);
        usb_free_urb(instance->urbs[i]);
    }

    kfree(instance->cell_buf);

    /* ATM finalize */
    if (instance->atm_dev) {
        atm_dev_deregister(instance->atm_dev);
        instance->atm_dev = NULL;
    }

    usbatm_put_instance(instance);  /* taken in usbatm_usb_probe */
}
EXPORT_SYMBOL_GPL(usbatm_usb_disconnect);


/***********
**  init  **
***********/

static int __init usbatm_usb_init(void)
{
    if (sizeof(struct usbatm_control) > FIELD_SIZEOF(struct sk_buff, cb)) {
        printk(KERN_ERR "%s unusable with this kernel!\n", usbatm_driver_name);
        return -EIO;
    }

    if ((num_rcv_urbs > UDSL_MAX_RCV_URBS)
        || (num_snd_urbs > UDSL_MAX_SND_URBS)
        || (rcv_buf_bytes < 1)
        || (rcv_buf_bytes > UDSL_MAX_BUF_SIZE)
        || (snd_buf_bytes < 1)
        || (snd_buf_bytes > UDSL_MAX_BUF_SIZE))
        return -EINVAL;

    return 0;
}
module_init(usbatm_usb_init);

static void __exit usbatm_usb_exit(void)
{
}
module_exit(usbatm_usb_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(DRIVER_VERSION);

/************
**  debug  **
************/

#ifdef VERBOSE_DEBUG
static int usbatm_print_packet(struct usbatm_data *instance,
                   const unsigned char *data, int len)
{
    unsigned char buffer[256];
    int i = 0, j = 0;

    for (i = 0; i < len;) {
        buffer[0] = '\0';
        sprintf(buffer, "%.3d :", i);
        for (j = 0; (j < 16) && (i < len); j++, i++)
            sprintf(buffer, "%s %2.2x", buffer, data[i]);
        dev_dbg(&instance->usb_intf->dev, "%s", buffer);
    }
    return i;
}
#endif