xref: /linux/drivers/net/usb/usbnet.c (revision 7f3edee81fbd49114c28057512906f169caa0bed)
1 /*
2  * USB Network driver infrastructure
3  * Copyright (C) 2000-2005 by David Brownell
4  * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  */
20 
21 /*
22  * This is a generic "USB networking" framework that works with several
23  * kinds of full and high speed networking devices:  host-to-host cables,
24  * smart usb peripherals, and actual Ethernet adapters.
25  *
26  * These devices usually differ in terms of control protocols (if they
27  * even have one!) and sometimes they define new framing to wrap or batch
28  * Ethernet packets.  Otherwise, they talk to USB pretty much the same,
29  * so interface (un)binding, endpoint I/O queues, fault handling, and other
30  * issues can usefully be addressed by this framework.
31  */
32 
33 // #define	DEBUG			// error path messages, extra info
34 // #define	VERBOSE			// more; success messages
35 
36 #include <linux/module.h>
37 #include <linux/init.h>
38 #include <linux/netdevice.h>
39 #include <linux/etherdevice.h>
40 #include <linux/ethtool.h>
41 #include <linux/workqueue.h>
42 #include <linux/mii.h>
43 #include <linux/usb.h>
44 
45 #include "usbnet.h"
46 
47 #define DRIVER_VERSION		"22-Aug-2005"
48 
49 
50 /*-------------------------------------------------------------------------*/
51 
52 /*
53  * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
54  * Several dozen bytes of IPv4 data can fit in two such transactions.
55  * One maximum size Ethernet packet takes twenty four of them.
56  * For high speed, each frame comfortably fits almost 36 max size
57  * Ethernet packets (so queues should be bigger).
58  *
59  * REVISIT qlens should be members of 'struct usbnet'; the goal is to
60  * let the USB host controller be busy for 5msec or more before an irq
61  * is required, under load.  Jumbograms change the equation.
62  */
63 #define RX_MAX_QUEUE_MEMORY (60 * 1518)
64 #define	RX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
65 			(RX_MAX_QUEUE_MEMORY/(dev)->rx_urb_size) : 4)
66 #define	TX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
67 			(RX_MAX_QUEUE_MEMORY/(dev)->hard_mtu) : 4)
68 
69 // reawaken network queue this soon after stopping; else watchdog barks
70 #define TX_TIMEOUT_JIFFIES	(5*HZ)
71 
72 // throttle rx/tx briefly after some faults, so khubd might disconnect()
73 // us (it polls at HZ/4 usually) before we report too many false errors.
74 #define THROTTLE_JIFFIES	(HZ/8)
75 
76 // between wakeups
77 #define UNLINK_TIMEOUT_MS	3
78 
79 /*-------------------------------------------------------------------------*/
80 
81 // randomly generated ethernet address
82 static u8	node_id [ETH_ALEN];
83 
84 static const char driver_name [] = "usbnet";
85 
86 /* use ethtool to change the level for any given device */
87 static int msg_level = -1;
88 module_param (msg_level, int, 0);
89 MODULE_PARM_DESC (msg_level, "Override default message level");
90 
91 /*-------------------------------------------------------------------------*/
92 
93 /* handles CDC Ethernet and many other network "bulk data" interfaces */
94 int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
95 {
96 	int				tmp;
97 	struct usb_host_interface	*alt = NULL;
98 	struct usb_host_endpoint	*in = NULL, *out = NULL;
99 	struct usb_host_endpoint	*status = NULL;
100 
101 	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
102 		unsigned	ep;
103 
104 		in = out = status = NULL;
105 		alt = intf->altsetting + tmp;
106 
107 		/* take the first altsetting with in-bulk + out-bulk;
108 		 * remember any status endpoint, just in case;
109 		 * ignore other endpoints and altsetttings.
110 		 */
111 		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
112 			struct usb_host_endpoint	*e;
113 			int				intr = 0;
114 
115 			e = alt->endpoint + ep;
116 			switch (e->desc.bmAttributes) {
117 			case USB_ENDPOINT_XFER_INT:
118 				if (!usb_endpoint_dir_in(&e->desc))
119 					continue;
120 				intr = 1;
121 				/* FALLTHROUGH */
122 			case USB_ENDPOINT_XFER_BULK:
123 				break;
124 			default:
125 				continue;
126 			}
127 			if (usb_endpoint_dir_in(&e->desc)) {
128 				if (!intr && !in)
129 					in = e;
130 				else if (intr && !status)
131 					status = e;
132 			} else {
133 				if (!out)
134 					out = e;
135 			}
136 		}
137 		if (in && out)
138 			break;
139 	}
140 	if (!alt || !in || !out)
141 		return -EINVAL;
142 
143 	if (alt->desc.bAlternateSetting != 0
144 			|| !(dev->driver_info->flags & FLAG_NO_SETINT)) {
145 		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
146 				alt->desc.bAlternateSetting);
147 		if (tmp < 0)
148 			return tmp;
149 	}
150 
151 	dev->in = usb_rcvbulkpipe (dev->udev,
152 			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
153 	dev->out = usb_sndbulkpipe (dev->udev,
154 			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
155 	dev->status = status;
156 	return 0;
157 }
158 EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
159 
160 static void intr_complete (struct urb *urb);
161 
162 static int init_status (struct usbnet *dev, struct usb_interface *intf)
163 {
164 	char		*buf = NULL;
165 	unsigned	pipe = 0;
166 	unsigned	maxp;
167 	unsigned	period;
168 
169 	if (!dev->driver_info->status)
170 		return 0;
171 
172 	pipe = usb_rcvintpipe (dev->udev,
173 			dev->status->desc.bEndpointAddress
174 				& USB_ENDPOINT_NUMBER_MASK);
175 	maxp = usb_maxpacket (dev->udev, pipe, 0);
176 
177 	/* avoid 1 msec chatter:  min 8 msec poll rate */
178 	period = max ((int) dev->status->desc.bInterval,
179 		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
180 
181 	buf = kmalloc (maxp, GFP_KERNEL);
182 	if (buf) {
183 		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
184 		if (!dev->interrupt) {
185 			kfree (buf);
186 			return -ENOMEM;
187 		} else {
188 			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
189 				buf, maxp, intr_complete, dev, period);
190 			dev_dbg(&intf->dev,
191 				"status ep%din, %d bytes period %d\n",
192 				usb_pipeendpoint(pipe), maxp, period);
193 		}
194 	}
195 	return 0;
196 }
197 
198 /* Passes this packet up the stack, updating its accounting.
199  * Some link protocols batch packets, so their rx_fixup paths
200  * can return clones as well as just modify the original skb.
201  */
202 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
203 {
204 	int	status;
205 
206 	skb->protocol = eth_type_trans (skb, dev->net);
207 	dev->stats.rx_packets++;
208 	dev->stats.rx_bytes += skb->len;
209 
210 	if (netif_msg_rx_status (dev))
211 		devdbg (dev, "< rx, len %zu, type 0x%x",
212 			skb->len + sizeof (struct ethhdr), skb->protocol);
213 	memset (skb->cb, 0, sizeof (struct skb_data));
214 	status = netif_rx (skb);
215 	if (status != NET_RX_SUCCESS && netif_msg_rx_err (dev))
216 		devdbg (dev, "netif_rx status %d", status);
217 }
218 EXPORT_SYMBOL_GPL(usbnet_skb_return);
219 
220 
221 /*-------------------------------------------------------------------------
222  *
223  * Network Device Driver (peer link to "Host Device", from USB host)
224  *
225  *-------------------------------------------------------------------------*/
226 
227 static int usbnet_change_mtu (struct net_device *net, int new_mtu)
228 {
229 	struct usbnet	*dev = netdev_priv(net);
230 	int		ll_mtu = new_mtu + net->hard_header_len;
231 	int		old_hard_mtu = dev->hard_mtu;
232 	int		old_rx_urb_size = dev->rx_urb_size;
233 
234 	if (new_mtu <= 0)
235 		return -EINVAL;
236 	// no second zero-length packet read wanted after mtu-sized packets
237 	if ((ll_mtu % dev->maxpacket) == 0)
238 		return -EDOM;
239 	net->mtu = new_mtu;
240 
241 	dev->hard_mtu = net->mtu + net->hard_header_len;
242 	if (dev->rx_urb_size == old_hard_mtu) {
243 		dev->rx_urb_size = dev->hard_mtu;
244 		if (dev->rx_urb_size > old_rx_urb_size)
245 			usbnet_unlink_rx_urbs(dev);
246 	}
247 
248 	return 0;
249 }
250 
251 /*-------------------------------------------------------------------------*/
252 
253 static struct net_device_stats *usbnet_get_stats (struct net_device *net)
254 {
255 	struct usbnet	*dev = netdev_priv(net);
256 	return &dev->stats;
257 }
258 
259 /*-------------------------------------------------------------------------*/
260 
261 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
262  * completion callbacks.  2.5 should have fixed those bugs...
263  */
264 
265 static void defer_bh(struct usbnet *dev, struct sk_buff *skb, struct sk_buff_head *list)
266 {
267 	unsigned long		flags;
268 
269 	spin_lock_irqsave(&list->lock, flags);
270 	__skb_unlink(skb, list);
271 	spin_unlock(&list->lock);
272 	spin_lock(&dev->done.lock);
273 	__skb_queue_tail(&dev->done, skb);
274 	if (dev->done.qlen == 1)
275 		tasklet_schedule(&dev->bh);
276 	spin_unlock_irqrestore(&dev->done.lock, flags);
277 }
278 
279 /* some work can't be done in tasklets, so we use keventd
280  *
281  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
282  * but tasklet_schedule() doesn't.  hope the failure is rare.
283  */
284 void usbnet_defer_kevent (struct usbnet *dev, int work)
285 {
286 	set_bit (work, &dev->flags);
287 	if (!schedule_work (&dev->kevent))
288 		deverr (dev, "kevent %d may have been dropped", work);
289 	else
290 		devdbg (dev, "kevent %d scheduled", work);
291 }
292 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
293 
294 /*-------------------------------------------------------------------------*/
295 
296 static void rx_complete (struct urb *urb);
297 
298 static void rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
299 {
300 	struct sk_buff		*skb;
301 	struct skb_data		*entry;
302 	int			retval = 0;
303 	unsigned long		lockflags;
304 	size_t			size = dev->rx_urb_size;
305 
306 	if ((skb = alloc_skb (size + NET_IP_ALIGN, flags)) == NULL) {
307 		if (netif_msg_rx_err (dev))
308 			devdbg (dev, "no rx skb");
309 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
310 		usb_free_urb (urb);
311 		return;
312 	}
313 	skb_reserve (skb, NET_IP_ALIGN);
314 
315 	entry = (struct skb_data *) skb->cb;
316 	entry->urb = urb;
317 	entry->dev = dev;
318 	entry->state = rx_start;
319 	entry->length = 0;
320 
321 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
322 		skb->data, size, rx_complete, skb);
323 
324 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
325 
326 	if (netif_running (dev->net)
327 			&& netif_device_present (dev->net)
328 			&& !test_bit (EVENT_RX_HALT, &dev->flags)) {
329 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
330 		case -EPIPE:
331 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
332 			break;
333 		case -ENOMEM:
334 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
335 			break;
336 		case -ENODEV:
337 			if (netif_msg_ifdown (dev))
338 				devdbg (dev, "device gone");
339 			netif_device_detach (dev->net);
340 			break;
341 		default:
342 			if (netif_msg_rx_err (dev))
343 				devdbg (dev, "rx submit, %d", retval);
344 			tasklet_schedule (&dev->bh);
345 			break;
346 		case 0:
347 			__skb_queue_tail (&dev->rxq, skb);
348 		}
349 	} else {
350 		if (netif_msg_ifdown (dev))
351 			devdbg (dev, "rx: stopped");
352 		retval = -ENOLINK;
353 	}
354 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
355 	if (retval) {
356 		dev_kfree_skb_any (skb);
357 		usb_free_urb (urb);
358 	}
359 }
360 
361 
362 /*-------------------------------------------------------------------------*/
363 
364 static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
365 {
366 	if (dev->driver_info->rx_fixup
367 			&& !dev->driver_info->rx_fixup (dev, skb))
368 		goto error;
369 	// else network stack removes extra byte if we forced a short packet
370 
371 	if (skb->len)
372 		usbnet_skb_return (dev, skb);
373 	else {
374 		if (netif_msg_rx_err (dev))
375 			devdbg (dev, "drop");
376 error:
377 		dev->stats.rx_errors++;
378 		skb_queue_tail (&dev->done, skb);
379 	}
380 }
381 
382 /*-------------------------------------------------------------------------*/
383 
384 static void rx_complete (struct urb *urb)
385 {
386 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
387 	struct skb_data		*entry = (struct skb_data *) skb->cb;
388 	struct usbnet		*dev = entry->dev;
389 	int			urb_status = urb->status;
390 
391 	skb_put (skb, urb->actual_length);
392 	entry->state = rx_done;
393 	entry->urb = NULL;
394 
395 	switch (urb_status) {
396 	/* success */
397 	case 0:
398 		if (skb->len < dev->net->hard_header_len) {
399 			entry->state = rx_cleanup;
400 			dev->stats.rx_errors++;
401 			dev->stats.rx_length_errors++;
402 			if (netif_msg_rx_err (dev))
403 				devdbg (dev, "rx length %d", skb->len);
404 		}
405 		break;
406 
407 	/* stalls need manual reset. this is rare ... except that
408 	 * when going through USB 2.0 TTs, unplug appears this way.
409 	 * we avoid the highspeed version of the ETIMEOUT/EILSEQ
410 	 * storm, recovering as needed.
411 	 */
412 	case -EPIPE:
413 		dev->stats.rx_errors++;
414 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
415 		// FALLTHROUGH
416 
417 	/* software-driven interface shutdown */
418 	case -ECONNRESET:		/* async unlink */
419 	case -ESHUTDOWN:		/* hardware gone */
420 		if (netif_msg_ifdown (dev))
421 			devdbg (dev, "rx shutdown, code %d", urb_status);
422 		goto block;
423 
424 	/* we get controller i/o faults during khubd disconnect() delays.
425 	 * throttle down resubmits, to avoid log floods; just temporarily,
426 	 * so we still recover when the fault isn't a khubd delay.
427 	 */
428 	case -EPROTO:
429 	case -ETIME:
430 	case -EILSEQ:
431 		dev->stats.rx_errors++;
432 		if (!timer_pending (&dev->delay)) {
433 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
434 			if (netif_msg_link (dev))
435 				devdbg (dev, "rx throttle %d", urb_status);
436 		}
437 block:
438 		entry->state = rx_cleanup;
439 		entry->urb = urb;
440 		urb = NULL;
441 		break;
442 
443 	/* data overrun ... flush fifo? */
444 	case -EOVERFLOW:
445 		dev->stats.rx_over_errors++;
446 		// FALLTHROUGH
447 
448 	default:
449 		entry->state = rx_cleanup;
450 		dev->stats.rx_errors++;
451 		if (netif_msg_rx_err (dev))
452 			devdbg (dev, "rx status %d", urb_status);
453 		break;
454 	}
455 
456 	defer_bh(dev, skb, &dev->rxq);
457 
458 	if (urb) {
459 		if (netif_running (dev->net)
460 				&& !test_bit (EVENT_RX_HALT, &dev->flags)) {
461 			rx_submit (dev, urb, GFP_ATOMIC);
462 			return;
463 		}
464 		usb_free_urb (urb);
465 	}
466 	if (netif_msg_rx_err (dev))
467 		devdbg (dev, "no read resubmitted");
468 }
469 
470 static void intr_complete (struct urb *urb)
471 {
472 	struct usbnet	*dev = urb->context;
473 	int		status = urb->status;
474 
475 	switch (status) {
476 	/* success */
477 	case 0:
478 		dev->driver_info->status(dev, urb);
479 		break;
480 
481 	/* software-driven interface shutdown */
482 	case -ENOENT:		/* urb killed */
483 	case -ESHUTDOWN:	/* hardware gone */
484 		if (netif_msg_ifdown (dev))
485 			devdbg (dev, "intr shutdown, code %d", status);
486 		return;
487 
488 	/* NOTE:  not throttling like RX/TX, since this endpoint
489 	 * already polls infrequently
490 	 */
491 	default:
492 		devdbg (dev, "intr status %d", status);
493 		break;
494 	}
495 
496 	if (!netif_running (dev->net))
497 		return;
498 
499 	memset(urb->transfer_buffer, 0, urb->transfer_buffer_length);
500 	status = usb_submit_urb (urb, GFP_ATOMIC);
501 	if (status != 0 && netif_msg_timer (dev))
502 		deverr(dev, "intr resubmit --> %d", status);
503 }
504 
505 /*-------------------------------------------------------------------------*/
506 
507 // unlink pending rx/tx; completion handlers do all other cleanup
508 
509 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
510 {
511 	unsigned long		flags;
512 	struct sk_buff		*skb, *skbnext;
513 	int			count = 0;
514 
515 	spin_lock_irqsave (&q->lock, flags);
516 	for (skb = q->next; skb != (struct sk_buff *) q; skb = skbnext) {
517 		struct skb_data		*entry;
518 		struct urb		*urb;
519 		int			retval;
520 
521 		entry = (struct skb_data *) skb->cb;
522 		urb = entry->urb;
523 		skbnext = skb->next;
524 
525 		// during some PM-driven resume scenarios,
526 		// these (async) unlinks complete immediately
527 		retval = usb_unlink_urb (urb);
528 		if (retval != -EINPROGRESS && retval != 0)
529 			devdbg (dev, "unlink urb err, %d", retval);
530 		else
531 			count++;
532 	}
533 	spin_unlock_irqrestore (&q->lock, flags);
534 	return count;
535 }
536 
537 // Flush all pending rx urbs
538 // minidrivers may need to do this when the MTU changes
539 
540 void usbnet_unlink_rx_urbs(struct usbnet *dev)
541 {
542 	if (netif_running(dev->net)) {
543 		(void) unlink_urbs (dev, &dev->rxq);
544 		tasklet_schedule(&dev->bh);
545 	}
546 }
547 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
548 
549 /*-------------------------------------------------------------------------*/
550 
551 // precondition: never called in_interrupt
552 
553 static int usbnet_stop (struct net_device *net)
554 {
555 	struct usbnet		*dev = netdev_priv(net);
556 	int			temp;
557 	DECLARE_WAIT_QUEUE_HEAD_ONSTACK (unlink_wakeup);
558 	DECLARE_WAITQUEUE (wait, current);
559 
560 	netif_stop_queue (net);
561 
562 	if (netif_msg_ifdown (dev))
563 		devinfo (dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld",
564 			dev->stats.rx_packets, dev->stats.tx_packets,
565 			dev->stats.rx_errors, dev->stats.tx_errors
566 			);
567 
568 	// ensure there are no more active urbs
569 	add_wait_queue (&unlink_wakeup, &wait);
570 	dev->wait = &unlink_wakeup;
571 	temp = unlink_urbs (dev, &dev->txq) + unlink_urbs (dev, &dev->rxq);
572 
573 	// maybe wait for deletions to finish.
574 	while (!skb_queue_empty(&dev->rxq)
575 			&& !skb_queue_empty(&dev->txq)
576 			&& !skb_queue_empty(&dev->done)) {
577 		msleep(UNLINK_TIMEOUT_MS);
578 		if (netif_msg_ifdown (dev))
579 			devdbg (dev, "waited for %d urb completions", temp);
580 	}
581 	dev->wait = NULL;
582 	remove_wait_queue (&unlink_wakeup, &wait);
583 
584 	usb_kill_urb(dev->interrupt);
585 
586 	/* deferred work (task, timer, softirq) must also stop.
587 	 * can't flush_scheduled_work() until we drop rtnl (later),
588 	 * else workers could deadlock; so make workers a NOP.
589 	 */
590 	dev->flags = 0;
591 	del_timer_sync (&dev->delay);
592 	tasklet_kill (&dev->bh);
593 	usb_autopm_put_interface(dev->intf);
594 
595 	return 0;
596 }
597 
598 /*-------------------------------------------------------------------------*/
599 
600 // posts reads, and enables write queuing
601 
602 // precondition: never called in_interrupt
603 
604 static int usbnet_open (struct net_device *net)
605 {
606 	struct usbnet		*dev = netdev_priv(net);
607 	int			retval;
608 	struct driver_info	*info = dev->driver_info;
609 
610 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
611 		if (netif_msg_ifup (dev))
612 			devinfo (dev,
613 				"resumption fail (%d) usbnet usb-%s-%s, %s",
614 				retval,
615 				dev->udev->bus->bus_name, dev->udev->devpath,
616 			info->description);
617 		goto done_nopm;
618 	}
619 
620 	// put into "known safe" state
621 	if (info->reset && (retval = info->reset (dev)) < 0) {
622 		if (netif_msg_ifup (dev))
623 			devinfo (dev,
624 				"open reset fail (%d) usbnet usb-%s-%s, %s",
625 				retval,
626 				dev->udev->bus->bus_name, dev->udev->devpath,
627 			info->description);
628 		goto done;
629 	}
630 
631 	// insist peer be connected
632 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
633 		if (netif_msg_ifup (dev))
634 			devdbg (dev, "can't open; %d", retval);
635 		goto done;
636 	}
637 
638 	/* start any status interrupt transfer */
639 	if (dev->interrupt) {
640 		retval = usb_submit_urb (dev->interrupt, GFP_KERNEL);
641 		if (retval < 0) {
642 			if (netif_msg_ifup (dev))
643 				deverr (dev, "intr submit %d", retval);
644 			goto done;
645 		}
646 	}
647 
648 	netif_start_queue (net);
649 	if (netif_msg_ifup (dev)) {
650 		char	*framing;
651 
652 		if (dev->driver_info->flags & FLAG_FRAMING_NC)
653 			framing = "NetChip";
654 		else if (dev->driver_info->flags & FLAG_FRAMING_GL)
655 			framing = "GeneSys";
656 		else if (dev->driver_info->flags & FLAG_FRAMING_Z)
657 			framing = "Zaurus";
658 		else if (dev->driver_info->flags & FLAG_FRAMING_RN)
659 			framing = "RNDIS";
660 		else if (dev->driver_info->flags & FLAG_FRAMING_AX)
661 			framing = "ASIX";
662 		else
663 			framing = "simple";
664 
665 		devinfo (dev, "open: enable queueing "
666 				"(rx %d, tx %d) mtu %d %s framing",
667 			(int)RX_QLEN (dev), (int)TX_QLEN (dev), dev->net->mtu,
668 			framing);
669 	}
670 
671 	// delay posting reads until we're fully open
672 	tasklet_schedule (&dev->bh);
673 	return retval;
674 done:
675 	usb_autopm_put_interface(dev->intf);
676 done_nopm:
677 	return retval;
678 }
679 
680 /*-------------------------------------------------------------------------*/
681 
682 /* ethtool methods; minidrivers may need to add some more, but
683  * they'll probably want to use this base set.
684  */
685 
686 int usbnet_get_settings (struct net_device *net, struct ethtool_cmd *cmd)
687 {
688 	struct usbnet *dev = netdev_priv(net);
689 
690 	if (!dev->mii.mdio_read)
691 		return -EOPNOTSUPP;
692 
693 	return mii_ethtool_gset(&dev->mii, cmd);
694 }
695 EXPORT_SYMBOL_GPL(usbnet_get_settings);
696 
697 int usbnet_set_settings (struct net_device *net, struct ethtool_cmd *cmd)
698 {
699 	struct usbnet *dev = netdev_priv(net);
700 	int retval;
701 
702 	if (!dev->mii.mdio_write)
703 		return -EOPNOTSUPP;
704 
705 	retval = mii_ethtool_sset(&dev->mii, cmd);
706 
707 	/* link speed/duplex might have changed */
708 	if (dev->driver_info->link_reset)
709 		dev->driver_info->link_reset(dev);
710 
711 	return retval;
712 
713 }
714 EXPORT_SYMBOL_GPL(usbnet_set_settings);
715 
716 u32 usbnet_get_link (struct net_device *net)
717 {
718 	struct usbnet *dev = netdev_priv(net);
719 
720 	/* If a check_connect is defined, return its result */
721 	if (dev->driver_info->check_connect)
722 		return dev->driver_info->check_connect (dev) == 0;
723 
724 	/* if the device has mii operations, use those */
725 	if (dev->mii.mdio_read)
726 		return mii_link_ok(&dev->mii);
727 
728 	/* Otherwise, say we're up (to avoid breaking scripts) */
729 	return 1;
730 }
731 EXPORT_SYMBOL_GPL(usbnet_get_link);
732 
733 int usbnet_nway_reset(struct net_device *net)
734 {
735 	struct usbnet *dev = netdev_priv(net);
736 
737 	if (!dev->mii.mdio_write)
738 		return -EOPNOTSUPP;
739 
740 	return mii_nway_restart(&dev->mii);
741 }
742 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
743 
744 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
745 {
746 	struct usbnet *dev = netdev_priv(net);
747 
748 	strncpy (info->driver, dev->driver_name, sizeof info->driver);
749 	strncpy (info->version, DRIVER_VERSION, sizeof info->version);
750 	strncpy (info->fw_version, dev->driver_info->description,
751 		sizeof info->fw_version);
752 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
753 }
754 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
755 
756 u32 usbnet_get_msglevel (struct net_device *net)
757 {
758 	struct usbnet *dev = netdev_priv(net);
759 
760 	return dev->msg_enable;
761 }
762 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
763 
764 void usbnet_set_msglevel (struct net_device *net, u32 level)
765 {
766 	struct usbnet *dev = netdev_priv(net);
767 
768 	dev->msg_enable = level;
769 }
770 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
771 
772 /* drivers may override default ethtool_ops in their bind() routine */
773 static struct ethtool_ops usbnet_ethtool_ops = {
774 	.get_settings		= usbnet_get_settings,
775 	.set_settings		= usbnet_set_settings,
776 	.get_link		= usbnet_get_link,
777 	.nway_reset		= usbnet_nway_reset,
778 	.get_drvinfo		= usbnet_get_drvinfo,
779 	.get_msglevel		= usbnet_get_msglevel,
780 	.set_msglevel		= usbnet_set_msglevel,
781 };
782 
783 /*-------------------------------------------------------------------------*/
784 
785 /* work that cannot be done in interrupt context uses keventd.
786  *
787  * NOTE:  with 2.5 we could do more of this using completion callbacks,
788  * especially now that control transfers can be queued.
789  */
790 static void
791 kevent (struct work_struct *work)
792 {
793 	struct usbnet		*dev =
794 		container_of(work, struct usbnet, kevent);
795 	int			status;
796 
797 	/* usb_clear_halt() needs a thread context */
798 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
799 		unlink_urbs (dev, &dev->txq);
800 		status = usb_clear_halt (dev->udev, dev->out);
801 		if (status < 0
802 				&& status != -EPIPE
803 				&& status != -ESHUTDOWN) {
804 			if (netif_msg_tx_err (dev))
805 				deverr (dev, "can't clear tx halt, status %d",
806 					status);
807 		} else {
808 			clear_bit (EVENT_TX_HALT, &dev->flags);
809 			if (status != -ESHUTDOWN)
810 				netif_wake_queue (dev->net);
811 		}
812 	}
813 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
814 		unlink_urbs (dev, &dev->rxq);
815 		status = usb_clear_halt (dev->udev, dev->in);
816 		if (status < 0
817 				&& status != -EPIPE
818 				&& status != -ESHUTDOWN) {
819 			if (netif_msg_rx_err (dev))
820 				deverr (dev, "can't clear rx halt, status %d",
821 					status);
822 		} else {
823 			clear_bit (EVENT_RX_HALT, &dev->flags);
824 			tasklet_schedule (&dev->bh);
825 		}
826 	}
827 
828 	/* tasklet could resubmit itself forever if memory is tight */
829 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
830 		struct urb	*urb = NULL;
831 
832 		if (netif_running (dev->net))
833 			urb = usb_alloc_urb (0, GFP_KERNEL);
834 		else
835 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
836 		if (urb != NULL) {
837 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
838 			rx_submit (dev, urb, GFP_KERNEL);
839 			tasklet_schedule (&dev->bh);
840 		}
841 	}
842 
843 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
844 		struct driver_info	*info = dev->driver_info;
845 		int			retval = 0;
846 
847 		clear_bit (EVENT_LINK_RESET, &dev->flags);
848 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
849 			devinfo(dev, "link reset failed (%d) usbnet usb-%s-%s, %s",
850 				retval,
851 				dev->udev->bus->bus_name, dev->udev->devpath,
852 				info->description);
853 		}
854 	}
855 
856 	if (dev->flags)
857 		devdbg (dev, "kevent done, flags = 0x%lx",
858 			dev->flags);
859 }
860 
861 /*-------------------------------------------------------------------------*/
862 
863 static void tx_complete (struct urb *urb)
864 {
865 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
866 	struct skb_data		*entry = (struct skb_data *) skb->cb;
867 	struct usbnet		*dev = entry->dev;
868 
869 	if (urb->status == 0) {
870 		dev->stats.tx_packets++;
871 		dev->stats.tx_bytes += entry->length;
872 	} else {
873 		dev->stats.tx_errors++;
874 
875 		switch (urb->status) {
876 		case -EPIPE:
877 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
878 			break;
879 
880 		/* software-driven interface shutdown */
881 		case -ECONNRESET:		// async unlink
882 		case -ESHUTDOWN:		// hardware gone
883 			break;
884 
885 		// like rx, tx gets controller i/o faults during khubd delays
886 		// and so it uses the same throttling mechanism.
887 		case -EPROTO:
888 		case -ETIME:
889 		case -EILSEQ:
890 			if (!timer_pending (&dev->delay)) {
891 				mod_timer (&dev->delay,
892 					jiffies + THROTTLE_JIFFIES);
893 				if (netif_msg_link (dev))
894 					devdbg (dev, "tx throttle %d",
895 							urb->status);
896 			}
897 			netif_stop_queue (dev->net);
898 			break;
899 		default:
900 			if (netif_msg_tx_err (dev))
901 				devdbg (dev, "tx err %d", entry->urb->status);
902 			break;
903 		}
904 	}
905 
906 	urb->dev = NULL;
907 	entry->state = tx_done;
908 	defer_bh(dev, skb, &dev->txq);
909 }
910 
911 /*-------------------------------------------------------------------------*/
912 
913 static void usbnet_tx_timeout (struct net_device *net)
914 {
915 	struct usbnet		*dev = netdev_priv(net);
916 
917 	unlink_urbs (dev, &dev->txq);
918 	tasklet_schedule (&dev->bh);
919 
920 	// FIXME: device recovery -- reset?
921 }
922 
923 /*-------------------------------------------------------------------------*/
924 
925 static int usbnet_start_xmit (struct sk_buff *skb, struct net_device *net)
926 {
927 	struct usbnet		*dev = netdev_priv(net);
928 	int			length;
929 	int			retval = NET_XMIT_SUCCESS;
930 	struct urb		*urb = NULL;
931 	struct skb_data		*entry;
932 	struct driver_info	*info = dev->driver_info;
933 	unsigned long		flags;
934 
935 	// some devices want funky USB-level framing, for
936 	// win32 driver (usually) and/or hardware quirks
937 	if (info->tx_fixup) {
938 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
939 		if (!skb) {
940 			if (netif_msg_tx_err (dev))
941 				devdbg (dev, "can't tx_fixup skb");
942 			goto drop;
943 		}
944 	}
945 	length = skb->len;
946 
947 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
948 		if (netif_msg_tx_err (dev))
949 			devdbg (dev, "no urb");
950 		goto drop;
951 	}
952 
953 	entry = (struct skb_data *) skb->cb;
954 	entry->urb = urb;
955 	entry->dev = dev;
956 	entry->state = tx_start;
957 	entry->length = length;
958 
959 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
960 			skb->data, skb->len, tx_complete, skb);
961 
962 	/* don't assume the hardware handles USB_ZERO_PACKET
963 	 * NOTE:  strictly conforming cdc-ether devices should expect
964 	 * the ZLP here, but ignore the one-byte packet.
965 	 */
966 	if ((length % dev->maxpacket) == 0) {
967 		urb->transfer_buffer_length++;
968 		if (skb_tailroom(skb)) {
969 			skb->data[skb->len] = 0;
970 			__skb_put(skb, 1);
971 		}
972 	}
973 
974 	spin_lock_irqsave (&dev->txq.lock, flags);
975 
976 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
977 	case -EPIPE:
978 		netif_stop_queue (net);
979 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
980 		break;
981 	default:
982 		if (netif_msg_tx_err (dev))
983 			devdbg (dev, "tx: submit urb err %d", retval);
984 		break;
985 	case 0:
986 		net->trans_start = jiffies;
987 		__skb_queue_tail (&dev->txq, skb);
988 		if (dev->txq.qlen >= TX_QLEN (dev))
989 			netif_stop_queue (net);
990 	}
991 	spin_unlock_irqrestore (&dev->txq.lock, flags);
992 
993 	if (retval) {
994 		if (netif_msg_tx_err (dev))
995 			devdbg (dev, "drop, code %d", retval);
996 drop:
997 		retval = NET_XMIT_SUCCESS;
998 		dev->stats.tx_dropped++;
999 		if (skb)
1000 			dev_kfree_skb_any (skb);
1001 		usb_free_urb (urb);
1002 	} else if (netif_msg_tx_queued (dev)) {
1003 		devdbg (dev, "> tx, len %d, type 0x%x",
1004 			length, skb->protocol);
1005 	}
1006 	return retval;
1007 }
1008 
1009 
1010 /*-------------------------------------------------------------------------*/
1011 
1012 // tasklet (work deferred from completions, in_irq) or timer
1013 
1014 static void usbnet_bh (unsigned long param)
1015 {
1016 	struct usbnet		*dev = (struct usbnet *) param;
1017 	struct sk_buff		*skb;
1018 	struct skb_data		*entry;
1019 
1020 	while ((skb = skb_dequeue (&dev->done))) {
1021 		entry = (struct skb_data *) skb->cb;
1022 		switch (entry->state) {
1023 		case rx_done:
1024 			entry->state = rx_cleanup;
1025 			rx_process (dev, skb);
1026 			continue;
1027 		case tx_done:
1028 		case rx_cleanup:
1029 			usb_free_urb (entry->urb);
1030 			dev_kfree_skb (skb);
1031 			continue;
1032 		default:
1033 			devdbg (dev, "bogus skb state %d", entry->state);
1034 		}
1035 	}
1036 
1037 	// waiting for all pending urbs to complete?
1038 	if (dev->wait) {
1039 		if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
1040 			wake_up (dev->wait);
1041 		}
1042 
1043 	// or are we maybe short a few urbs?
1044 	} else if (netif_running (dev->net)
1045 			&& netif_device_present (dev->net)
1046 			&& !timer_pending (&dev->delay)
1047 			&& !test_bit (EVENT_RX_HALT, &dev->flags)) {
1048 		int	temp = dev->rxq.qlen;
1049 		int	qlen = RX_QLEN (dev);
1050 
1051 		if (temp < qlen) {
1052 			struct urb	*urb;
1053 			int		i;
1054 
1055 			// don't refill the queue all at once
1056 			for (i = 0; i < 10 && dev->rxq.qlen < qlen; i++) {
1057 				urb = usb_alloc_urb (0, GFP_ATOMIC);
1058 				if (urb != NULL)
1059 					rx_submit (dev, urb, GFP_ATOMIC);
1060 			}
1061 			if (temp != dev->rxq.qlen && netif_msg_link (dev))
1062 				devdbg (dev, "rxqlen %d --> %d",
1063 						temp, dev->rxq.qlen);
1064 			if (dev->rxq.qlen < qlen)
1065 				tasklet_schedule (&dev->bh);
1066 		}
1067 		if (dev->txq.qlen < TX_QLEN (dev))
1068 			netif_wake_queue (dev->net);
1069 	}
1070 }
1071 
1072 
1073 
1074 /*-------------------------------------------------------------------------
1075  *
1076  * USB Device Driver support
1077  *
1078  *-------------------------------------------------------------------------*/
1079 
1080 // precondition: never called in_interrupt
1081 
1082 void usbnet_disconnect (struct usb_interface *intf)
1083 {
1084 	struct usbnet		*dev;
1085 	struct usb_device	*xdev;
1086 	struct net_device	*net;
1087 
1088 	dev = usb_get_intfdata(intf);
1089 	usb_set_intfdata(intf, NULL);
1090 	if (!dev)
1091 		return;
1092 
1093 	xdev = interface_to_usbdev (intf);
1094 
1095 	if (netif_msg_probe (dev))
1096 		devinfo (dev, "unregister '%s' usb-%s-%s, %s",
1097 			intf->dev.driver->name,
1098 			xdev->bus->bus_name, xdev->devpath,
1099 			dev->driver_info->description);
1100 
1101 	net = dev->net;
1102 	unregister_netdev (net);
1103 
1104 	/* we don't hold rtnl here ... */
1105 	flush_scheduled_work ();
1106 
1107 	if (dev->driver_info->unbind)
1108 		dev->driver_info->unbind (dev, intf);
1109 
1110 	free_netdev(net);
1111 	usb_put_dev (xdev);
1112 }
1113 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1114 
1115 
1116 /*-------------------------------------------------------------------------*/
1117 
1118 // precondition: never called in_interrupt
1119 
1120 int
1121 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1122 {
1123 	struct usbnet			*dev;
1124 	struct net_device		*net;
1125 	struct usb_host_interface	*interface;
1126 	struct driver_info		*info;
1127 	struct usb_device		*xdev;
1128 	int				status;
1129 	const char			*name;
1130 	DECLARE_MAC_BUF(mac);
1131 
1132 	name = udev->dev.driver->name;
1133 	info = (struct driver_info *) prod->driver_info;
1134 	if (!info) {
1135 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1136 		return -ENODEV;
1137 	}
1138 	xdev = interface_to_usbdev (udev);
1139 	interface = udev->cur_altsetting;
1140 
1141 	usb_get_dev (xdev);
1142 
1143 	status = -ENOMEM;
1144 
1145 	// set up our own records
1146 	net = alloc_etherdev(sizeof(*dev));
1147 	if (!net) {
1148 		dbg ("can't kmalloc dev");
1149 		goto out;
1150 	}
1151 
1152 	dev = netdev_priv(net);
1153 	dev->udev = xdev;
1154 	dev->intf = udev;
1155 	dev->driver_info = info;
1156 	dev->driver_name = name;
1157 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1158 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1159 	skb_queue_head_init (&dev->rxq);
1160 	skb_queue_head_init (&dev->txq);
1161 	skb_queue_head_init (&dev->done);
1162 	dev->bh.func = usbnet_bh;
1163 	dev->bh.data = (unsigned long) dev;
1164 	INIT_WORK (&dev->kevent, kevent);
1165 	dev->delay.function = usbnet_bh;
1166 	dev->delay.data = (unsigned long) dev;
1167 	init_timer (&dev->delay);
1168 	mutex_init (&dev->phy_mutex);
1169 
1170 	dev->net = net;
1171 	strcpy (net->name, "usb%d");
1172 	memcpy (net->dev_addr, node_id, sizeof node_id);
1173 
1174 	/* rx and tx sides can use different message sizes;
1175 	 * bind() should set rx_urb_size in that case.
1176 	 */
1177 	dev->hard_mtu = net->mtu + net->hard_header_len;
1178 #if 0
1179 // dma_supported() is deeply broken on almost all architectures
1180 	// possible with some EHCI controllers
1181 	if (dma_supported (&udev->dev, DMA_64BIT_MASK))
1182 		net->features |= NETIF_F_HIGHDMA;
1183 #endif
1184 
1185 	net->change_mtu = usbnet_change_mtu;
1186 	net->get_stats = usbnet_get_stats;
1187 	net->hard_start_xmit = usbnet_start_xmit;
1188 	net->open = usbnet_open;
1189 	net->stop = usbnet_stop;
1190 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1191 	net->tx_timeout = usbnet_tx_timeout;
1192 	net->ethtool_ops = &usbnet_ethtool_ops;
1193 
1194 	// allow device-specific bind/init procedures
1195 	// NOTE net->name still not usable ...
1196 	if (info->bind) {
1197 		status = info->bind (dev, udev);
1198 		if (status < 0)
1199 			goto out1;
1200 
1201 		// heuristic:  "usb%d" for links we know are two-host,
1202 		// else "eth%d" when there's reasonable doubt.  userspace
1203 		// can rename the link if it knows better.
1204 		if ((dev->driver_info->flags & FLAG_ETHER) != 0
1205 				&& (net->dev_addr [0] & 0x02) == 0)
1206 			strcpy (net->name, "eth%d");
1207 
1208 		/* maybe the remote can't receive an Ethernet MTU */
1209 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1210 			net->mtu = dev->hard_mtu - net->hard_header_len;
1211 	} else if (!info->in || !info->out)
1212 		status = usbnet_get_endpoints (dev, udev);
1213 	else {
1214 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1215 		dev->out = usb_sndbulkpipe (xdev, info->out);
1216 		if (!(info->flags & FLAG_NO_SETINT))
1217 			status = usb_set_interface (xdev,
1218 				interface->desc.bInterfaceNumber,
1219 				interface->desc.bAlternateSetting);
1220 		else
1221 			status = 0;
1222 
1223 	}
1224 	if (status >= 0 && dev->status)
1225 		status = init_status (dev, udev);
1226 	if (status < 0)
1227 		goto out3;
1228 
1229 	if (!dev->rx_urb_size)
1230 		dev->rx_urb_size = dev->hard_mtu;
1231 	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
1232 
1233 	SET_NETDEV_DEV(net, &udev->dev);
1234 	status = register_netdev (net);
1235 	if (status)
1236 		goto out3;
1237 	if (netif_msg_probe (dev))
1238 		devinfo (dev, "register '%s' at usb-%s-%s, %s, %s",
1239 			udev->dev.driver->name,
1240 			xdev->bus->bus_name, xdev->devpath,
1241 			dev->driver_info->description,
1242 			print_mac(mac, net->dev_addr));
1243 
1244 	// ok, it's ready to go.
1245 	usb_set_intfdata (udev, dev);
1246 
1247 	// start as if the link is up
1248 	netif_device_attach (net);
1249 
1250 	return 0;
1251 
1252 out3:
1253 	if (info->unbind)
1254 		info->unbind (dev, udev);
1255 out1:
1256 	free_netdev(net);
1257 out:
1258 	usb_put_dev(xdev);
1259 	return status;
1260 }
1261 EXPORT_SYMBOL_GPL(usbnet_probe);
1262 
1263 /*-------------------------------------------------------------------------*/
1264 
1265 /*
1266  * suspend the whole driver as soon as the first interface is suspended
1267  * resume only when the last interface is resumed
1268  */
1269 
1270 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1271 {
1272 	struct usbnet		*dev = usb_get_intfdata(intf);
1273 
1274 	if (!dev->suspend_count++) {
1275 		/*
1276 		 * accelerate emptying of the rx and queues, to avoid
1277 		 * having everything error out.
1278 		 */
1279 		netif_device_detach (dev->net);
1280 		(void) unlink_urbs (dev, &dev->rxq);
1281 		(void) unlink_urbs (dev, &dev->txq);
1282 		/*
1283 		 * reattach so runtime management can use and
1284 		 * wake the device
1285 		 */
1286 		netif_device_attach (dev->net);
1287 	}
1288 	return 0;
1289 }
1290 EXPORT_SYMBOL_GPL(usbnet_suspend);
1291 
1292 int usbnet_resume (struct usb_interface *intf)
1293 {
1294 	struct usbnet		*dev = usb_get_intfdata(intf);
1295 
1296 	if (!--dev->suspend_count)
1297 		tasklet_schedule (&dev->bh);
1298 
1299 	return 0;
1300 }
1301 EXPORT_SYMBOL_GPL(usbnet_resume);
1302 
1303 
1304 /*-------------------------------------------------------------------------*/
1305 
1306 static int __init usbnet_init(void)
1307 {
1308 	/* compiler should optimize this out */
1309 	BUILD_BUG_ON (sizeof (((struct sk_buff *)0)->cb)
1310 			< sizeof (struct skb_data));
1311 
1312 	random_ether_addr(node_id);
1313 	return 0;
1314 }
1315 module_init(usbnet_init);
1316 
1317 static void __exit usbnet_exit(void)
1318 {
1319 }
1320 module_exit(usbnet_exit);
1321 
1322 MODULE_AUTHOR("David Brownell");
1323 MODULE_DESCRIPTION("USB network driver framework");
1324 MODULE_LICENSE("GPL");
1325