usbatm.c

底层驱动开发

/******************************************************************************
 *  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 ([e-mail]) 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 ([e-mail])
 *
 *  1.5A:	- Version for inclusion in 2.5 series kernel
 *		- Modifications by Richard Purdie ([e-mail])
 *		- 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 [e-mail])
 *
 *  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 <[e-mail]>"
#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;
	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 ((vci != cached_vci) || (vpi != cached_vpi)) {
			cached_vpi = vpi;
			cached_vci = vci;

			cached_vcc = usbatm_find_vcc(instance, vpi, vci);

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

		if (!cached_vcc)
			continue;

		vcc = cached_vcc->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 = cached_vcc->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);
		}
	}
}