Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1328 insertions, 0 deletions

diff --git a/drivers/usb/atm/usbatm.c b/drivers/usb/atm/usbatm.c
new file mode 100644
index 000000000..1cdb8758a
--- /dev/null
+++ b/drivers/usb/atm/usbatm.c
@@ -0,0 +1,1328 @@
+// SPDX-License-Identifier: GPL-2.0+
+/******************************************************************************
+ *  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
+ ******************************************************************************/
+
+/*
+ *  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 <linux/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/signal.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 <duncan.sands@free.fr>"
+#define DRIVER_DESC	"Generic USB ATM/DSL I/O"
+
+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 const 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); */
+
+	/* Can be invoked from task context, protect against interrupts */
+	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);
+
+	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);
+	}
+
+	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);
+
+		skb = dev_alloc_skb(length);
+		if (!skb) {
+			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;
+
+		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;
+
+	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(struct tasklet_struct *t)
+{
+	struct usbatm_data *instance = from_tasklet(instance, t,
+						    rx_channel.tasklet);
+	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;
+
+					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(struct tasklet_struct *t)
+{
+	struct usbatm_data *instance = from_tasklet(instance, t,
+						    tx_channel.tasklet);
+	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;
+
+	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);
+}
+
+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;
+
+	/* racy disconnection check - fine */
+	if (!instance || instance->disconnected) {
+#ifdef VERBOSE_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);
+
+	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)
+{
+	kref_get(&instance->refcount);
+}
+
+static void usbatm_put_instance(struct usbatm_data *instance)
+{
+	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;
+
+	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;
+
+	/* 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;
+	}
+
+	new = kzalloc(sizeof(struct usbatm_vcc_data), GFP_KERNEL);
+	if (!new) {
+		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;
+
+	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);
+}
+
+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);
+
+	kthread_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, "%s",
+			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(struct timer_list *t)
+{
+	struct usbatm_channel *channel = from_timer(channel, t, delay);
+
+	tasklet_schedule(&channel->tasklet);
+}
+
+static void usbatm_init_channel(struct usbatm_channel *channel)
+{
+	spin_lock_init(&channel->lock);
+	INIT_LIST_HEAD(&channel->list);
+	timer_setup(&channel->delay, usbatm_tasklet_schedule, 0);
+}
+
+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;
+	size_t size;
+
+	/* instance init */
+	size = struct_size(instance, urbs, num_rcv_urbs + num_snd_urbs);
+	instance = kzalloc(size, GFP_KERNEL);
+	if (!instance)
+		return -ENOMEM;
+
+	/* public fields */
+
+	instance->driver = driver;
+	strscpy(instance->driver_name, driver->driver_name,
+		sizeof(instance->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_setup(&instance->rx_channel.tasklet, usbatm_rx_process);
+	tasklet_setup(&instance->tx_channel.tasklet, usbatm_tx_process);
+	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);
+
+	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;
+
+	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);
+	}
+
+	/* 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;
+
+		urb = usb_alloc_urb(iso_packets, GFP_KERNEL);
+		if (!urb) {
+			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) {
+			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) {
+		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;
+
+	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) > sizeof_field(struct sk_buff, cb)) {
+		pr_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");
+
+/************
+**  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