[PATCH] USB ATM: new usbatm core

Rework the core usbatm code: minidrivers (i.e. drivers for particular
modems) now register themselves with the usbatm core, supplying methods
for binding/unbinding etc.  The design was inspired by usb-serial and
usbnet.  At the same time, more common code from the speedtch and
cxacru (patch 3/5) drivers was generalized and moved into the core.  The
transmission and reception parts have been unified and simplified.  Since
this is a major change and I don't like underscores in file names,
usb_atm.[ch] has been renamed usbatm.[ch].

Many thanks to Roman Kagan, who did a lot of the coding.

Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1231 insertions, 0 deletions

diff --git a/drivers/usb/atm/usbatm.c b/drivers/usb/atm/usbatm.c
new file mode 100644
index 000000000000..e134e2794486
--- /dev/null
+++ b/drivers/usb/atm/usbatm.c
@@ -0,0 +1,1231 @@
+/******************************************************************************
+ *  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 (duncan.sands@free.fr) 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 (oliver@neukum.name)
+ *
+ *  1.5A:       - Version for inclusion in 2.5 series kernel
+ *              - Modifications by Richard Purdie (rpurdie@rpsys.net)
+ *              - 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 stephen.robinson@zen.co.uk)
+ *
+ *  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/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/stat.h>
+#include <linux/timer.h>
+#include <linux/wait.h>
+
+#ifdef VERBOSE_DEBUG
+static int usbatm_print_packet(const unsigned char *data, int len);
+#define PACKETDEBUG(arg...)     usbatm_print_packet (arg)
+#define vdbg(arg...)            dbg (arg)
+#else
+#define PACKETDEBUG(arg...)
+#define vdbg(arg...)
+#endif
+
+#define DRIVER_AUTHOR   "Johan Verrept, Duncan Sands <duncan.sands@free.fr>"
+#define DRIVER_VERSION  "1.9"
+#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_RCV_BUF_SIZE           1024    /* ATM cells */
+#define UDSL_MAX_SND_BUF_SIZE           1024    /* ATM cells */
+#define UDSL_DEFAULT_RCV_URBS           4
+#define UDSL_DEFAULT_SND_URBS           4
+#define UDSL_DEFAULT_RCV_BUF_SIZE       64      /* ATM cells */
+#define UDSL_DEFAULT_SND_BUF_SIZE       64      /* ATM cells */
+
+#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_size = UDSL_DEFAULT_RCV_BUF_SIZE;
+static unsigned int snd_buf_size = 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_size, uint, S_IRUGO);
+MODULE_PARM_DESC(rcv_buf_size,
+                 "Size of the buffers used for reception in ATM cells (range: 1-"
+                 __MODULE_STRING(UDSL_MAX_RCV_BUF_SIZE) ", default: "
+                 __MODULE_STRING(UDSL_DEFAULT_RCV_BUF_SIZE) ")");
+
+module_param(snd_buf_size, uint, S_IRUGO);
+MODULE_PARM_DESC(snd_buf_size,
+                 "Size of the buffers used for transmission in ATM cells (range: 1-"
+                 __MODULE_STRING(UDSL_MAX_SND_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 *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 *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(skb);
+}
+
+
+/***********
+**  urbs  **
+************/
+
+static inline 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 inline 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) {
+                atm_dbg(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 pt_regs *regs)
+{
+        struct usbatm_channel *channel = urb->context;
+        unsigned long flags;
+
+        vdbg("%s: urb 0x%p, status %d, actual_length %d",
+             __func__, urb, 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(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;
+
+        list_for_each_entry(vcc, &instance->vcc_list, list)
+                if ((vcc->vci == vci) && (vcc->vpi == vpi))
+                        return vcc;
+        return NULL;
+}
+
+static void usbatm_extract_cells(struct usbatm_data *instance,
+                               unsigned char *source, unsigned int avail_data)
+{
+        struct usbatm_vcc_data *cached_vcc = NULL;
+        struct atm_vcc *vcc;
+        struct sk_buff *sarb;
+        struct usbatm_vcc_data *vcc_data;
+        unsigned int stride = instance->rx_channel.stride;
+        int vci, cached_vci = 0;
+        short vpi, cached_vpi = 0;
+        u8 pti;
+
+        for (; avail_data >= stride; avail_data -= stride, source += stride) {
+                vpi = ((source[0] & 0x0f) << 4)  | (source[1] >> 4);
+                vci = ((source[1] & 0x0f) << 12) | (source[2] << 4) | (source[3] >> 4);
+                pti = ((source[3] & 0xe) >> 1);
+
+                vdbg("%s: vpi %hd, vci %d, pti %d", __func__, vpi, vci, pti);
+
+                if (cached_vcc && (vci == cached_vci) && (vpi == cached_vpi))
+                        vcc_data = cached_vcc;
+                else if ((vcc_data = usbatm_find_vcc(instance, vpi, vci))) {
+                        cached_vcc = vcc_data;
+                        cached_vpi = vpi;
+                        cached_vci = vci;
+                } else {
+                        atm_dbg(instance, "%s: unknown vpi/vci (%hd/%d)!\n", __func__, vpi, vci);
+                        continue;
+                }
+
+                vcc = vcc_data->vcc;
+
+                /* OAM F5 end-to-end */
+                if (pti == ATM_PTI_E2EF5) {
+                        atm_warn(instance, "%s: OAM not supported (vpi %d, vci %d)!\n", __func__, vpi, vci);
+                        atomic_inc(&vcc->stats->rx_err);
+                        continue;
+                }
+
+                sarb = vcc_data->sarb;
+
+                if (sarb->tail + ATM_CELL_PAYLOAD > sarb->end) {
+                        atm_dbg(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(sarb->tail + ATM_CELL_PAYLOAD <= sarb->end);
+                }
+
+                memcpy(sarb->tail, 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_dbg(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_dbg(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, sarb->tail - pdu_length, pdu_length) != 0xc704dd7b) {
+                                atm_dbg(instance, "%s: packet failed crc check (vcc: 0x%p)!\n",
+                                                __func__, vcc);
+                                atomic_inc(&vcc->stats->rx_err);
+                                goto out;
+                        }
+
+                        vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);
+
+                        if (!(skb = dev_alloc_skb(length))) {
+                                atm_dbg(instance, "%s: no memory for skb (length: %u)!\n", __func__, length);
+                                atomic_inc(&vcc->stats->rx_drop);
+                                goto out;
+                        }
+
+                        vdbg("%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);
+
+                        if (!atm_charge(vcc, skb->truesize)) {
+                                atm_dbg(instance, "%s: failed atm_charge (skb->truesize: %u)!\n", __func__, skb->truesize);
+                                dev_kfree_skb(skb);
+                                goto out;       /* atm_charge increments rx_drop */
+                        }
+
+                        memcpy(skb->data, sarb->tail - pdu_length, length);
+                        __skb_put(skb, length);
+
+                        vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
+                             __func__, skb, skb->len, skb->truesize);
+
+                        PACKETDEBUG(skb->data, skb->len);
+
+                        vcc->push(vcc, skb);
+
+                        atomic_inc(&vcc->stats->rx);
+                out:
+                        skb_trim(sarb, 0);
+                }
+        }
+}
+
+
+/*************
+**  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 num_written;
+        unsigned int stride = instance->tx_channel.stride;
+
+        vdbg("%s: skb->len=%d, avail_space=%u", __func__, skb->len, avail_space);
+        UDSL_ASSERT(!(avail_space % stride));
+
+        for (num_written = 0; num_written < avail_space && ctrl->len;
+             num_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;
+
+                memcpy(ptr, skb->data, 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 num_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("%s: processing urb 0x%p", __func__, urb);
+
+                if (usb_pipeisoc(urb->pipe)) {
+                        int i;
+                        for (i = 0; i < urb->number_of_packets; i++)
+                                if (!urb->iso_frame_desc[i].status)
+                                        usbatm_extract_cells(instance,
+                                                             (u8 *)urb->transfer_buffer + urb->iso_frame_desc[i].offset,
+                                                             urb->iso_frame_desc[i].actual_length);
+                }
+                else
+                        if (!urb->status)
+                                usbatm_extract_cells(instance, urb->transfer_buffer, urb->actual_length);
+
+                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 num_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;
+                        num_written = (urb->status == -EAGAIN) ?
+                                urb->transfer_buffer_length : 0;
+                }
+
+                num_written += usbatm_write_cells(instance, skb,
+                                                  buffer + num_written,
+                                                  buf_size - num_written);
+
+                vdbg("%s: wrote %u bytes from skb 0x%p to urb 0x%p",
+                     __func__, num_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 (num_written == buf_size || (!skb && num_written)) {
+                        urb->transfer_buffer_length = num_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);
+        for (skb = instance->sndqueue.next, n = skb->next;
+             skb != (struct sk_buff *)&instance->sndqueue;
+             skb = n, n = skb->next)
+                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("%s called (skb 0x%p, len %u)", __func__, skb, skb->len);
+
+        if (!instance) {
+                dbg("%s: NULL data!", __func__);
+                err = -ENODEV;
+                goto fail;
+        }
+
+        if (vcc->qos.aal != ATM_AAL5) {
+                atm_dbg(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
+                err = -EINVAL;
+                goto fail;
+        }
+
+        if (skb->len > ATM_MAX_AAL5_PDU) {
+                atm_dbg(instance, "%s: packet too long (%d vs %d)!\n",
+                                __func__, skb->len, ATM_MAX_AAL5_PDU);
+                err = -EINVAL;
+                goto fail;
+        }
+
+        PACKETDEBUG(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);
+
+        dbg("%s", __func__);
+
+        tasklet_kill(&instance->rx_channel.tasklet);
+        tasklet_kill(&instance->tx_channel.tasklet);
+        usb_put_dev(instance->usb_dev);
+        kfree(instance);
+}
+
+void usbatm_get_instance(struct usbatm_data *instance)
+{
+        dbg("%s", __func__);
+
+        kref_get(&instance->refcount);
+}
+
+void usbatm_put_instance(struct usbatm_data *instance)
+{
+        dbg("%s", __func__);
+
+        kref_put(&instance->refcount, usbatm_destroy_instance);
+}
+
+
+/**********
+**  ATM  **
+**********/
+
+static void usbatm_atm_dev_close(struct atm_dev *dev)
+{
+        struct usbatm_data *instance = dev->dev_data;
+
+        dbg("%s", __func__);
+
+        if (!instance)
+                return;
+
+        dev->dev_data = NULL;
+        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) {
+                dbg("%s: NULL instance!", __func__);
+                return -ENODEV;
+        }
+
+        if (!left--)
+                return sprintf(page, "%s\n", instance->description);
+
+        if (!left--)
+                return sprintf(page, "MAC: %02x:%02x:%02x:%02x:%02x:%02x\n",
+                               atm_dev->esi[0], atm_dev->esi[1],
+                               atm_dev->esi[2], atm_dev->esi[3],
+                               atm_dev->esi[4], atm_dev->esi[5]);
+
+        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--)
+                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) {
+                dbg("%s: NULL data!", __func__);
+                return -ENODEV;
+        }
+
+        atm_dbg(instance, "%s: vpi %hd, vci %d\n", __func__, vpi, vci);
+
+        /* only support AAL5 */
+        if ((vcc->qos.aal != ATM_AAL5) || (vcc->qos.rxtp.max_sdu < 0)
+            || (vcc->qos.rxtp.max_sdu > ATM_MAX_AAL5_PDU)) {
+                atm_dbg(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
+                return -EINVAL;
+        }
+
+        down(&instance->serialize);     /* vs self, usbatm_atm_close */
+
+        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 = kmalloc(sizeof(struct usbatm_vcc_data), GFP_KERNEL))) {
+                atm_dbg(instance, "%s: no memory for vcc_data!\n", __func__);
+                ret = -ENOMEM;
+                goto fail;
+        }
+
+        memset(new, 0, sizeof(struct usbatm_vcc_data));
+        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_dbg(instance, "%s: no memory for SAR buffer!\n", __func__);
+                ret = -ENOMEM;
+                goto fail;
+        }
+
+        vcc->dev_data = new;
+
+        tasklet_disable(&instance->rx_channel.tasklet);
+        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);
+
+        up(&instance->serialize);
+
+        atm_dbg(instance, "%s: allocated vcc data 0x%p\n", __func__, new);
+
+        return 0;
+
+fail:
+        kfree(new);
+        up(&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) {
+                dbg("%s: NULL data!", __func__);
+                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);
+
+        down(&instance->serialize);     /* vs self, usbatm_atm_open */
+
+        tasklet_disable(&instance->rx_channel.tasklet);
+        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);
+
+        up(&instance->serialize);
+
+        atm_dbg(instance, "%s successful\n", __func__);
+}
+
+static int usbatm_atm_ioctl(struct atm_dev *dev, unsigned int cmd,
+                          void __user * arg)
+{
+        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 */
+        atm_dev = atm_dev_register(instance->driver_name, &usbatm_atm_devops, -1, NULL);
+        if (!atm_dev) {
+                usb_dbg(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_dbg(instance, "%s: atm_start failed: %d!\n", __func__, ret);
+                goto fail;
+        }
+
+        /* ready for ATM callbacks */
+        usbatm_get_instance(instance);  /* dropped in usbatm_atm_dev_close */
+        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;
+        shutdown_atm_dev(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;
+
+        daemonize(instance->driver->driver_name);
+        allow_signal(SIGTERM);
+
+        complete(&instance->thread_started);
+
+        ret = instance->driver->heavy_init(instance, instance->usb_intf);
+
+        if (!ret)
+                ret = usbatm_atm_init(instance);
+
+        down(&instance->serialize);
+        instance->thread_pid = -1;
+        up(&instance->serialize);
+
+        complete_and_exit(&instance->thread_exited, ret);
+}
+
+static int usbatm_heavy_init(struct usbatm_data *instance)
+{
+        int ret = kernel_thread(usbatm_do_heavy_init, instance, CLONE_KERNEL);
+
+        if (ret < 0) {
+                usb_dbg(instance, "%s: failed to create kernel_thread (%d)!\n", __func__, ret);
+                return ret;
+        }
+
+        down(&instance->serialize);
+        instance->thread_pid = ret;
+        up(&instance->serialize);
+
+        wait_for_completion(&instance->thread_started);
+
+        return 0;
+}
+
+static void usbatm_tasklet_schedule(unsigned long data)
+{
+        tasklet_schedule((struct tasklet_struct *) data);
+}
+
+static inline 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;
+        int need_heavy;
+
+        dev_dbg(dev, "%s: trying driver %s with vendor=0x%x, product=0x%x, ifnum %d\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 = kmalloc(sizeof(*instance) + sizeof(struct urb *) * (num_rcv_urbs + num_snd_urbs),
+                           GFP_KERNEL);
+        if (!instance) {
+                dev_dbg(dev, "%s: no memory for instance data!\n", __func__);
+                return -ENOMEM;
+        }
+
+        memset(instance, 0, sizeof(*instance));
+
+        /* 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:
+        need_heavy = 1;
+        if (driver->bind && (error = driver->bind(instance, intf, id, &need_heavy)) < 0) {
+                        dev_dbg(dev, "%s: bind failed: %d!\n", __func__, error);
+                        goto fail_free;
+        }
+
+        /* private fields */
+
+        kref_init(&instance->refcount);         /* dropped in usbatm_usb_disconnect */
+        init_MUTEX(&instance->serialize);
+
+        instance->thread_pid = -1;
+        init_completion(&instance->thread_started);
+        init_completion(&instance->thread_exited);
+
+        INIT_LIST_HEAD(&instance->vcc_list);
+
+        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.endpoint = usb_rcvbulkpipe(usb_dev, driver->in);
+        instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->out);
+        instance->rx_channel.stride = ATM_CELL_SIZE + driver->rx_padding;
+        instance->tx_channel.stride = ATM_CELL_SIZE + driver->tx_padding;
+        instance->rx_channel.buf_size = rcv_buf_size * instance->rx_channel.stride;
+        instance->tx_channel.buf_size = snd_buf_size * instance->tx_channel.stride;
+        instance->rx_channel.usbatm = instance->tx_channel.usbatm = instance;
+
+        skb_queue_head_init(&instance->sndqueue);
+
+        for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
+                struct urb *urb;
+                u8 *buffer;
+                unsigned int iso_packets = 0, iso_size = 0;
+                struct usbatm_channel *channel = i < num_rcv_urbs ?
+                        &instance->rx_channel : &instance->tx_channel;
+
+                if (usb_pipeisoc(channel->endpoint)) {
+                        /* don't expect iso out endpoints */
+                        iso_size = usb_maxpacket(instance->usb_dev, channel->endpoint, 0);
+                        iso_size -= iso_size % channel->stride; /* alignment */
+                        BUG_ON(!iso_size);
+                        iso_packets = (channel->buf_size - 1) / iso_size + 1;
+                }
+
+                urb = usb_alloc_urb(iso_packets, GFP_KERNEL);
+                if (!urb) {
+                        dev_dbg(dev, "%s: no memory for urb %d!\n", __func__, i);
+                        goto fail_unbind;
+                }
+
+                buffer = kmalloc(channel->buf_size, GFP_KERNEL);
+                if (!buffer) {
+                        dev_dbg(dev, "%s: no memory for buffer %d!\n", __func__, i);
+                        goto fail_unbind;
+                }
+                memset(buffer, 0, channel->buf_size);
+
+                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 = iso_size * j;
+                                urb->iso_frame_desc[j].length = min_t(int, iso_size,
+                                                                      channel->buf_size - urb->iso_frame_desc[j].offset);
+                        }
+                }
+
+                /* put all tx URBs on the list of spares */
+                if (i >= num_rcv_urbs)
+                        list_add_tail(&urb->urb_list, &channel->list);
+
+                vdbg("%s: alloced buffer 0x%p buf size %u urb 0x%p",
+                     __func__, urb->transfer_buffer, urb->transfer_buffer_length, urb);
+                instance->urbs[i] = urb;
+        }
+
+        if (need_heavy && 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:
+        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);
+        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);
+
+        down(&instance->serialize);
+        if (instance->thread_pid >= 0)
+                kill_proc(instance->thread_pid, SIGTERM, 1);
+        up(&instance->serialize);
+
+        wait_for_completion(&instance->thread_exited);
+
+        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);
+
+        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;
+
+        /* turn usbatm_[rt]x_process into noop */
+        /* 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);
+
+        for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
+                kfree(instance->urbs[i]->transfer_buffer);
+                usb_free_urb(instance->urbs[i]);
+        }
+
+        /* ATM finalize */
+        if (instance->atm_dev)
+                shutdown_atm_dev(instance->atm_dev);
+
+        usbatm_put_instance(instance);  /* taken in usbatm_usb_probe */
+}
+EXPORT_SYMBOL_GPL(usbatm_usb_disconnect);
+
+
+/***********
+**  init  **
+***********/
+
+static int __init usbatm_usb_init(void)
+{
+        dbg("%s: driver version %s", __func__, DRIVER_VERSION);
+
+        if (sizeof(struct usbatm_control) > sizeof(((struct sk_buff *) 0)->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_size < 1)
+            || (rcv_buf_size > UDSL_MAX_RCV_BUF_SIZE)
+            || (snd_buf_size < 1)
+            || (snd_buf_size > UDSL_MAX_SND_BUF_SIZE))
+                return -EINVAL;
+
+        return 0;
+}
+module_init(usbatm_usb_init);
+
+static void __exit usbatm_usb_exit(void)
+{
+        dbg("%s", __func__);
+}
+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(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]);
+                }
+                dbg("%s", buffer);
+        }
+        return i;
+}
+#endif