xref: /openbmc/linux/drivers/net/usb/usbnet.c (revision e23feb16)
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/ctype.h>
41 #include <linux/ethtool.h>
42 #include <linux/workqueue.h>
43 #include <linux/mii.h>
44 #include <linux/usb.h>
45 #include <linux/usb/usbnet.h>
46 #include <linux/slab.h>
47 #include <linux/kernel.h>
48 #include <linux/pm_runtime.h>
49 
50 #define DRIVER_VERSION		"22-Aug-2005"
51 
52 
53 /*-------------------------------------------------------------------------*/
54 
55 /*
56  * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
57  * Several dozen bytes of IPv4 data can fit in two such transactions.
58  * One maximum size Ethernet packet takes twenty four of them.
59  * For high speed, each frame comfortably fits almost 36 max size
60  * Ethernet packets (so queues should be bigger).
61  *
62  * The goal is to let the USB host controller be busy for 5msec or
63  * more before an irq is required, under load.  Jumbograms change
64  * the equation.
65  */
66 #define	MAX_QUEUE_MEMORY	(60 * 1518)
67 #define	RX_QLEN(dev)		((dev)->rx_qlen)
68 #define	TX_QLEN(dev)		((dev)->tx_qlen)
69 
70 // reawaken network queue this soon after stopping; else watchdog barks
71 #define TX_TIMEOUT_JIFFIES	(5*HZ)
72 
73 // throttle rx/tx briefly after some faults, so khubd might disconnect()
74 // us (it polls at HZ/4 usually) before we report too many false errors.
75 #define THROTTLE_JIFFIES	(HZ/8)
76 
77 // between wakeups
78 #define UNLINK_TIMEOUT_MS	3
79 
80 /*-------------------------------------------------------------------------*/
81 
82 // randomly generated ethernet address
83 static u8	node_id [ETH_ALEN];
84 
85 static const char driver_name [] = "usbnet";
86 
87 /* use ethtool to change the level for any given device */
88 static int msg_level = -1;
89 module_param (msg_level, int, 0);
90 MODULE_PARM_DESC (msg_level, "Override default message level");
91 
92 /*-------------------------------------------------------------------------*/
93 
94 /* handles CDC Ethernet and many other network "bulk data" interfaces */
95 int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
96 {
97 	int				tmp;
98 	struct usb_host_interface	*alt = NULL;
99 	struct usb_host_endpoint	*in = NULL, *out = NULL;
100 	struct usb_host_endpoint	*status = NULL;
101 
102 	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
103 		unsigned	ep;
104 
105 		in = out = status = NULL;
106 		alt = intf->altsetting + tmp;
107 
108 		/* take the first altsetting with in-bulk + out-bulk;
109 		 * remember any status endpoint, just in case;
110 		 * ignore other endpoints and altsettings.
111 		 */
112 		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
113 			struct usb_host_endpoint	*e;
114 			int				intr = 0;
115 
116 			e = alt->endpoint + ep;
117 			switch (e->desc.bmAttributes) {
118 			case USB_ENDPOINT_XFER_INT:
119 				if (!usb_endpoint_dir_in(&e->desc))
120 					continue;
121 				intr = 1;
122 				/* FALLTHROUGH */
123 			case USB_ENDPOINT_XFER_BULK:
124 				break;
125 			default:
126 				continue;
127 			}
128 			if (usb_endpoint_dir_in(&e->desc)) {
129 				if (!intr && !in)
130 					in = e;
131 				else if (intr && !status)
132 					status = e;
133 			} else {
134 				if (!out)
135 					out = e;
136 			}
137 		}
138 		if (in && out)
139 			break;
140 	}
141 	if (!alt || !in || !out)
142 		return -EINVAL;
143 
144 	if (alt->desc.bAlternateSetting != 0 ||
145 	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
146 		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
147 				alt->desc.bAlternateSetting);
148 		if (tmp < 0)
149 			return tmp;
150 	}
151 
152 	dev->in = usb_rcvbulkpipe (dev->udev,
153 			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
154 	dev->out = usb_sndbulkpipe (dev->udev,
155 			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
156 	dev->status = status;
157 	return 0;
158 }
159 EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
160 
161 int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
162 {
163 	int 		tmp, i;
164 	unsigned char	buf [13];
165 
166 	tmp = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
167 	if (tmp != 12) {
168 		dev_dbg(&dev->udev->dev,
169 			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
170 		if (tmp >= 0)
171 			tmp = -EINVAL;
172 		return tmp;
173 	}
174 	for (i = tmp = 0; i < 6; i++, tmp += 2)
175 		dev->net->dev_addr [i] =
176 			(hex_to_bin(buf[tmp]) << 4) + hex_to_bin(buf[tmp + 1]);
177 	return 0;
178 }
179 EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
180 
181 static void intr_complete (struct urb *urb)
182 {
183 	struct usbnet	*dev = urb->context;
184 	int		status = urb->status;
185 
186 	switch (status) {
187 	/* success */
188 	case 0:
189 		dev->driver_info->status(dev, urb);
190 		break;
191 
192 	/* software-driven interface shutdown */
193 	case -ENOENT:		/* urb killed */
194 	case -ESHUTDOWN:	/* hardware gone */
195 		netif_dbg(dev, ifdown, dev->net,
196 			  "intr shutdown, code %d\n", status);
197 		return;
198 
199 	/* NOTE:  not throttling like RX/TX, since this endpoint
200 	 * already polls infrequently
201 	 */
202 	default:
203 		netdev_dbg(dev->net, "intr status %d\n", status);
204 		break;
205 	}
206 
207 	if (!netif_running (dev->net))
208 		return;
209 
210 	status = usb_submit_urb (urb, GFP_ATOMIC);
211 	if (status != 0)
212 		netif_err(dev, timer, dev->net,
213 			  "intr resubmit --> %d\n", status);
214 }
215 
216 static int init_status (struct usbnet *dev, struct usb_interface *intf)
217 {
218 	char		*buf = NULL;
219 	unsigned	pipe = 0;
220 	unsigned	maxp;
221 	unsigned	period;
222 
223 	if (!dev->driver_info->status)
224 		return 0;
225 
226 	pipe = usb_rcvintpipe (dev->udev,
227 			dev->status->desc.bEndpointAddress
228 				& USB_ENDPOINT_NUMBER_MASK);
229 	maxp = usb_maxpacket (dev->udev, pipe, 0);
230 
231 	/* avoid 1 msec chatter:  min 8 msec poll rate */
232 	period = max ((int) dev->status->desc.bInterval,
233 		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
234 
235 	buf = kmalloc (maxp, GFP_KERNEL);
236 	if (buf) {
237 		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
238 		if (!dev->interrupt) {
239 			kfree (buf);
240 			return -ENOMEM;
241 		} else {
242 			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
243 				buf, maxp, intr_complete, dev, period);
244 			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
245 			dev_dbg(&intf->dev,
246 				"status ep%din, %d bytes period %d\n",
247 				usb_pipeendpoint(pipe), maxp, period);
248 		}
249 	}
250 	return 0;
251 }
252 
253 /* Submit the interrupt URB if not previously submitted, increasing refcount */
254 int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
255 {
256 	int ret = 0;
257 
258 	WARN_ON_ONCE(dev->interrupt == NULL);
259 	if (dev->interrupt) {
260 		mutex_lock(&dev->interrupt_mutex);
261 
262 		if (++dev->interrupt_count == 1)
263 			ret = usb_submit_urb(dev->interrupt, mem_flags);
264 
265 		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
266 			dev->interrupt_count);
267 		mutex_unlock(&dev->interrupt_mutex);
268 	}
269 	return ret;
270 }
271 EXPORT_SYMBOL_GPL(usbnet_status_start);
272 
273 /* For resume; submit interrupt URB if previously submitted */
274 static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
275 {
276 	int ret = 0;
277 
278 	mutex_lock(&dev->interrupt_mutex);
279 	if (dev->interrupt_count) {
280 		ret = usb_submit_urb(dev->interrupt, mem_flags);
281 		dev_dbg(&dev->udev->dev,
282 			"submitted interrupt URB for resume\n");
283 	}
284 	mutex_unlock(&dev->interrupt_mutex);
285 	return ret;
286 }
287 
288 /* Kill the interrupt URB if all submitters want it killed */
289 void usbnet_status_stop(struct usbnet *dev)
290 {
291 	if (dev->interrupt) {
292 		mutex_lock(&dev->interrupt_mutex);
293 		WARN_ON(dev->interrupt_count == 0);
294 
295 		if (dev->interrupt_count && --dev->interrupt_count == 0)
296 			usb_kill_urb(dev->interrupt);
297 
298 		dev_dbg(&dev->udev->dev,
299 			"decremented interrupt URB count to %d\n",
300 			dev->interrupt_count);
301 		mutex_unlock(&dev->interrupt_mutex);
302 	}
303 }
304 EXPORT_SYMBOL_GPL(usbnet_status_stop);
305 
306 /* For suspend; always kill interrupt URB */
307 static void __usbnet_status_stop_force(struct usbnet *dev)
308 {
309 	if (dev->interrupt) {
310 		mutex_lock(&dev->interrupt_mutex);
311 		usb_kill_urb(dev->interrupt);
312 		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
313 		mutex_unlock(&dev->interrupt_mutex);
314 	}
315 }
316 
317 /* Passes this packet up the stack, updating its accounting.
318  * Some link protocols batch packets, so their rx_fixup paths
319  * can return clones as well as just modify the original skb.
320  */
321 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
322 {
323 	int	status;
324 
325 	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
326 		skb_queue_tail(&dev->rxq_pause, skb);
327 		return;
328 	}
329 
330 	skb->protocol = eth_type_trans (skb, dev->net);
331 	dev->net->stats.rx_packets++;
332 	dev->net->stats.rx_bytes += skb->len;
333 
334 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
335 		  skb->len + sizeof (struct ethhdr), skb->protocol);
336 	memset (skb->cb, 0, sizeof (struct skb_data));
337 
338 	if (skb_defer_rx_timestamp(skb))
339 		return;
340 
341 	status = netif_rx (skb);
342 	if (status != NET_RX_SUCCESS)
343 		netif_dbg(dev, rx_err, dev->net,
344 			  "netif_rx status %d\n", status);
345 }
346 EXPORT_SYMBOL_GPL(usbnet_skb_return);
347 
348 /* must be called if hard_mtu or rx_urb_size changed */
349 void usbnet_update_max_qlen(struct usbnet *dev)
350 {
351 	enum usb_device_speed speed = dev->udev->speed;
352 
353 	switch (speed) {
354 	case USB_SPEED_HIGH:
355 		dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
356 		dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
357 		break;
358 	case USB_SPEED_SUPER:
359 		/*
360 		 * Not take default 5ms qlen for super speed HC to
361 		 * save memory, and iperf tests show 2.5ms qlen can
362 		 * work well
363 		 */
364 		dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
365 		dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
366 		break;
367 	default:
368 		dev->rx_qlen = dev->tx_qlen = 4;
369 	}
370 }
371 EXPORT_SYMBOL_GPL(usbnet_update_max_qlen);
372 
373 
374 /*-------------------------------------------------------------------------
375  *
376  * Network Device Driver (peer link to "Host Device", from USB host)
377  *
378  *-------------------------------------------------------------------------*/
379 
380 int usbnet_change_mtu (struct net_device *net, int new_mtu)
381 {
382 	struct usbnet	*dev = netdev_priv(net);
383 	int		ll_mtu = new_mtu + net->hard_header_len;
384 	int		old_hard_mtu = dev->hard_mtu;
385 	int		old_rx_urb_size = dev->rx_urb_size;
386 
387 	if (new_mtu <= 0)
388 		return -EINVAL;
389 	// no second zero-length packet read wanted after mtu-sized packets
390 	if ((ll_mtu % dev->maxpacket) == 0)
391 		return -EDOM;
392 	net->mtu = new_mtu;
393 
394 	dev->hard_mtu = net->mtu + net->hard_header_len;
395 	if (dev->rx_urb_size == old_hard_mtu) {
396 		dev->rx_urb_size = dev->hard_mtu;
397 		if (dev->rx_urb_size > old_rx_urb_size)
398 			usbnet_unlink_rx_urbs(dev);
399 	}
400 
401 	/* max qlen depend on hard_mtu and rx_urb_size */
402 	usbnet_update_max_qlen(dev);
403 
404 	return 0;
405 }
406 EXPORT_SYMBOL_GPL(usbnet_change_mtu);
407 
408 /* The caller must hold list->lock */
409 static void __usbnet_queue_skb(struct sk_buff_head *list,
410 			struct sk_buff *newsk, enum skb_state state)
411 {
412 	struct skb_data *entry = (struct skb_data *) newsk->cb;
413 
414 	__skb_queue_tail(list, newsk);
415 	entry->state = state;
416 }
417 
418 /*-------------------------------------------------------------------------*/
419 
420 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
421  * completion callbacks.  2.5 should have fixed those bugs...
422  */
423 
424 static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
425 		struct sk_buff_head *list, enum skb_state state)
426 {
427 	unsigned long		flags;
428 	enum skb_state 		old_state;
429 	struct skb_data *entry = (struct skb_data *) skb->cb;
430 
431 	spin_lock_irqsave(&list->lock, flags);
432 	old_state = entry->state;
433 	entry->state = state;
434 	__skb_unlink(skb, list);
435 	spin_unlock(&list->lock);
436 	spin_lock(&dev->done.lock);
437 	__skb_queue_tail(&dev->done, skb);
438 	if (dev->done.qlen == 1)
439 		tasklet_schedule(&dev->bh);
440 	spin_unlock_irqrestore(&dev->done.lock, flags);
441 	return old_state;
442 }
443 
444 /* some work can't be done in tasklets, so we use keventd
445  *
446  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
447  * but tasklet_schedule() doesn't.  hope the failure is rare.
448  */
449 void usbnet_defer_kevent (struct usbnet *dev, int work)
450 {
451 	set_bit (work, &dev->flags);
452 	if (!schedule_work (&dev->kevent)) {
453 		if (net_ratelimit())
454 			netdev_err(dev->net, "kevent %d may have been dropped\n", work);
455 	} else {
456 		netdev_dbg(dev->net, "kevent %d scheduled\n", work);
457 	}
458 }
459 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
460 
461 /*-------------------------------------------------------------------------*/
462 
463 static void rx_complete (struct urb *urb);
464 
465 static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
466 {
467 	struct sk_buff		*skb;
468 	struct skb_data		*entry;
469 	int			retval = 0;
470 	unsigned long		lockflags;
471 	size_t			size = dev->rx_urb_size;
472 
473 	/* prevent rx skb allocation when error ratio is high */
474 	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
475 		usb_free_urb(urb);
476 		return -ENOLINK;
477 	}
478 
479 	skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
480 	if (!skb) {
481 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
482 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
483 		usb_free_urb (urb);
484 		return -ENOMEM;
485 	}
486 
487 	entry = (struct skb_data *) skb->cb;
488 	entry->urb = urb;
489 	entry->dev = dev;
490 	entry->length = 0;
491 
492 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
493 		skb->data, size, rx_complete, skb);
494 
495 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
496 
497 	if (netif_running (dev->net) &&
498 	    netif_device_present (dev->net) &&
499 	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
500 	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
501 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
502 		case -EPIPE:
503 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
504 			break;
505 		case -ENOMEM:
506 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
507 			break;
508 		case -ENODEV:
509 			netif_dbg(dev, ifdown, dev->net, "device gone\n");
510 			netif_device_detach (dev->net);
511 			break;
512 		case -EHOSTUNREACH:
513 			retval = -ENOLINK;
514 			break;
515 		default:
516 			netif_dbg(dev, rx_err, dev->net,
517 				  "rx submit, %d\n", retval);
518 			tasklet_schedule (&dev->bh);
519 			break;
520 		case 0:
521 			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
522 		}
523 	} else {
524 		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
525 		retval = -ENOLINK;
526 	}
527 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
528 	if (retval) {
529 		dev_kfree_skb_any (skb);
530 		usb_free_urb (urb);
531 	}
532 	return retval;
533 }
534 
535 
536 /*-------------------------------------------------------------------------*/
537 
538 static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
539 {
540 	if (dev->driver_info->rx_fixup &&
541 	    !dev->driver_info->rx_fixup (dev, skb)) {
542 		/* With RX_ASSEMBLE, rx_fixup() must update counters */
543 		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
544 			dev->net->stats.rx_errors++;
545 		goto done;
546 	}
547 	// else network stack removes extra byte if we forced a short packet
548 
549 	if (skb->len) {
550 		/* all data was already cloned from skb inside the driver */
551 		if (dev->driver_info->flags & FLAG_MULTI_PACKET)
552 			dev_kfree_skb_any(skb);
553 		else
554 			usbnet_skb_return(dev, skb);
555 		return;
556 	}
557 
558 	netif_dbg(dev, rx_err, dev->net, "drop\n");
559 	dev->net->stats.rx_errors++;
560 done:
561 	skb_queue_tail(&dev->done, skb);
562 }
563 
564 /*-------------------------------------------------------------------------*/
565 
566 static void rx_complete (struct urb *urb)
567 {
568 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
569 	struct skb_data		*entry = (struct skb_data *) skb->cb;
570 	struct usbnet		*dev = entry->dev;
571 	int			urb_status = urb->status;
572 	enum skb_state		state;
573 
574 	skb_put (skb, urb->actual_length);
575 	state = rx_done;
576 	entry->urb = NULL;
577 
578 	switch (urb_status) {
579 	/* success */
580 	case 0:
581 		if (skb->len < dev->net->hard_header_len) {
582 			state = rx_cleanup;
583 			dev->net->stats.rx_errors++;
584 			dev->net->stats.rx_length_errors++;
585 			netif_dbg(dev, rx_err, dev->net,
586 				  "rx length %d\n", skb->len);
587 		}
588 		break;
589 
590 	/* stalls need manual reset. this is rare ... except that
591 	 * when going through USB 2.0 TTs, unplug appears this way.
592 	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
593 	 * storm, recovering as needed.
594 	 */
595 	case -EPIPE:
596 		dev->net->stats.rx_errors++;
597 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
598 		// FALLTHROUGH
599 
600 	/* software-driven interface shutdown */
601 	case -ECONNRESET:		/* async unlink */
602 	case -ESHUTDOWN:		/* hardware gone */
603 		netif_dbg(dev, ifdown, dev->net,
604 			  "rx shutdown, code %d\n", urb_status);
605 		goto block;
606 
607 	/* we get controller i/o faults during khubd disconnect() delays.
608 	 * throttle down resubmits, to avoid log floods; just temporarily,
609 	 * so we still recover when the fault isn't a khubd delay.
610 	 */
611 	case -EPROTO:
612 	case -ETIME:
613 	case -EILSEQ:
614 		dev->net->stats.rx_errors++;
615 		if (!timer_pending (&dev->delay)) {
616 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
617 			netif_dbg(dev, link, dev->net,
618 				  "rx throttle %d\n", urb_status);
619 		}
620 block:
621 		state = rx_cleanup;
622 		entry->urb = urb;
623 		urb = NULL;
624 		break;
625 
626 	/* data overrun ... flush fifo? */
627 	case -EOVERFLOW:
628 		dev->net->stats.rx_over_errors++;
629 		// FALLTHROUGH
630 
631 	default:
632 		state = rx_cleanup;
633 		dev->net->stats.rx_errors++;
634 		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
635 		break;
636 	}
637 
638 	/* stop rx if packet error rate is high */
639 	if (++dev->pkt_cnt > 30) {
640 		dev->pkt_cnt = 0;
641 		dev->pkt_err = 0;
642 	} else {
643 		if (state == rx_cleanup)
644 			dev->pkt_err++;
645 		if (dev->pkt_err > 20)
646 			set_bit(EVENT_RX_KILL, &dev->flags);
647 	}
648 
649 	state = defer_bh(dev, skb, &dev->rxq, state);
650 
651 	if (urb) {
652 		if (netif_running (dev->net) &&
653 		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
654 		    state != unlink_start) {
655 			rx_submit (dev, urb, GFP_ATOMIC);
656 			usb_mark_last_busy(dev->udev);
657 			return;
658 		}
659 		usb_free_urb (urb);
660 	}
661 	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
662 }
663 
664 /*-------------------------------------------------------------------------*/
665 void usbnet_pause_rx(struct usbnet *dev)
666 {
667 	set_bit(EVENT_RX_PAUSED, &dev->flags);
668 
669 	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
670 }
671 EXPORT_SYMBOL_GPL(usbnet_pause_rx);
672 
673 void usbnet_resume_rx(struct usbnet *dev)
674 {
675 	struct sk_buff *skb;
676 	int num = 0;
677 
678 	clear_bit(EVENT_RX_PAUSED, &dev->flags);
679 
680 	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
681 		usbnet_skb_return(dev, skb);
682 		num++;
683 	}
684 
685 	tasklet_schedule(&dev->bh);
686 
687 	netif_dbg(dev, rx_status, dev->net,
688 		  "paused rx queue disabled, %d skbs requeued\n", num);
689 }
690 EXPORT_SYMBOL_GPL(usbnet_resume_rx);
691 
692 void usbnet_purge_paused_rxq(struct usbnet *dev)
693 {
694 	skb_queue_purge(&dev->rxq_pause);
695 }
696 EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
697 
698 /*-------------------------------------------------------------------------*/
699 
700 // unlink pending rx/tx; completion handlers do all other cleanup
701 
702 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
703 {
704 	unsigned long		flags;
705 	struct sk_buff		*skb;
706 	int			count = 0;
707 
708 	spin_lock_irqsave (&q->lock, flags);
709 	while (!skb_queue_empty(q)) {
710 		struct skb_data		*entry;
711 		struct urb		*urb;
712 		int			retval;
713 
714 		skb_queue_walk(q, skb) {
715 			entry = (struct skb_data *) skb->cb;
716 			if (entry->state != unlink_start)
717 				goto found;
718 		}
719 		break;
720 found:
721 		entry->state = unlink_start;
722 		urb = entry->urb;
723 
724 		/*
725 		 * Get reference count of the URB to avoid it to be
726 		 * freed during usb_unlink_urb, which may trigger
727 		 * use-after-free problem inside usb_unlink_urb since
728 		 * usb_unlink_urb is always racing with .complete
729 		 * handler(include defer_bh).
730 		 */
731 		usb_get_urb(urb);
732 		spin_unlock_irqrestore(&q->lock, flags);
733 		// during some PM-driven resume scenarios,
734 		// these (async) unlinks complete immediately
735 		retval = usb_unlink_urb (urb);
736 		if (retval != -EINPROGRESS && retval != 0)
737 			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
738 		else
739 			count++;
740 		usb_put_urb(urb);
741 		spin_lock_irqsave(&q->lock, flags);
742 	}
743 	spin_unlock_irqrestore (&q->lock, flags);
744 	return count;
745 }
746 
747 // Flush all pending rx urbs
748 // minidrivers may need to do this when the MTU changes
749 
750 void usbnet_unlink_rx_urbs(struct usbnet *dev)
751 {
752 	if (netif_running(dev->net)) {
753 		(void) unlink_urbs (dev, &dev->rxq);
754 		tasklet_schedule(&dev->bh);
755 	}
756 }
757 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
758 
759 /*-------------------------------------------------------------------------*/
760 
761 // precondition: never called in_interrupt
762 static void usbnet_terminate_urbs(struct usbnet *dev)
763 {
764 	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);
765 	DECLARE_WAITQUEUE(wait, current);
766 	int temp;
767 
768 	/* ensure there are no more active urbs */
769 	add_wait_queue(&unlink_wakeup, &wait);
770 	set_current_state(TASK_UNINTERRUPTIBLE);
771 	dev->wait = &unlink_wakeup;
772 	temp = unlink_urbs(dev, &dev->txq) +
773 		unlink_urbs(dev, &dev->rxq);
774 
775 	/* maybe wait for deletions to finish. */
776 	while (!skb_queue_empty(&dev->rxq)
777 		&& !skb_queue_empty(&dev->txq)
778 		&& !skb_queue_empty(&dev->done)) {
779 			schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
780 			set_current_state(TASK_UNINTERRUPTIBLE);
781 			netif_dbg(dev, ifdown, dev->net,
782 				  "waited for %d urb completions\n", temp);
783 	}
784 	set_current_state(TASK_RUNNING);
785 	dev->wait = NULL;
786 	remove_wait_queue(&unlink_wakeup, &wait);
787 }
788 
789 int usbnet_stop (struct net_device *net)
790 {
791 	struct usbnet		*dev = netdev_priv(net);
792 	struct driver_info	*info = dev->driver_info;
793 	int			retval;
794 
795 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
796 	netif_stop_queue (net);
797 
798 	netif_info(dev, ifdown, dev->net,
799 		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
800 		   net->stats.rx_packets, net->stats.tx_packets,
801 		   net->stats.rx_errors, net->stats.tx_errors);
802 
803 	/* allow minidriver to stop correctly (wireless devices to turn off
804 	 * radio etc) */
805 	if (info->stop) {
806 		retval = info->stop(dev);
807 		if (retval < 0)
808 			netif_info(dev, ifdown, dev->net,
809 				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
810 				   retval,
811 				   dev->udev->bus->bus_name, dev->udev->devpath,
812 				   info->description);
813 	}
814 
815 	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
816 		usbnet_terminate_urbs(dev);
817 
818 	usbnet_status_stop(dev);
819 
820 	usbnet_purge_paused_rxq(dev);
821 
822 	/* deferred work (task, timer, softirq) must also stop.
823 	 * can't flush_scheduled_work() until we drop rtnl (later),
824 	 * else workers could deadlock; so make workers a NOP.
825 	 */
826 	dev->flags = 0;
827 	del_timer_sync (&dev->delay);
828 	tasklet_kill (&dev->bh);
829 	if (info->manage_power &&
830 	    !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
831 		info->manage_power(dev, 0);
832 	else
833 		usb_autopm_put_interface(dev->intf);
834 
835 	return 0;
836 }
837 EXPORT_SYMBOL_GPL(usbnet_stop);
838 
839 /*-------------------------------------------------------------------------*/
840 
841 // posts reads, and enables write queuing
842 
843 // precondition: never called in_interrupt
844 
845 int usbnet_open (struct net_device *net)
846 {
847 	struct usbnet		*dev = netdev_priv(net);
848 	int			retval;
849 	struct driver_info	*info = dev->driver_info;
850 
851 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
852 		netif_info(dev, ifup, dev->net,
853 			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
854 			   retval,
855 			   dev->udev->bus->bus_name,
856 			   dev->udev->devpath,
857 			   info->description);
858 		goto done_nopm;
859 	}
860 
861 	// put into "known safe" state
862 	if (info->reset && (retval = info->reset (dev)) < 0) {
863 		netif_info(dev, ifup, dev->net,
864 			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
865 			   retval,
866 			   dev->udev->bus->bus_name,
867 			   dev->udev->devpath,
868 			   info->description);
869 		goto done;
870 	}
871 
872 	/* hard_mtu or rx_urb_size may change in reset() */
873 	usbnet_update_max_qlen(dev);
874 
875 	// insist peer be connected
876 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
877 		netif_dbg(dev, ifup, dev->net, "can't open; %d\n", retval);
878 		goto done;
879 	}
880 
881 	/* start any status interrupt transfer */
882 	if (dev->interrupt) {
883 		retval = usbnet_status_start(dev, GFP_KERNEL);
884 		if (retval < 0) {
885 			netif_err(dev, ifup, dev->net,
886 				  "intr submit %d\n", retval);
887 			goto done;
888 		}
889 	}
890 
891 	set_bit(EVENT_DEV_OPEN, &dev->flags);
892 	netif_start_queue (net);
893 	netif_info(dev, ifup, dev->net,
894 		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
895 		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
896 		   dev->net->mtu,
897 		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
898 		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
899 		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
900 		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
901 		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
902 		   "simple");
903 
904 	/* reset rx error state */
905 	dev->pkt_cnt = 0;
906 	dev->pkt_err = 0;
907 	clear_bit(EVENT_RX_KILL, &dev->flags);
908 
909 	// delay posting reads until we're fully open
910 	tasklet_schedule (&dev->bh);
911 	if (info->manage_power) {
912 		retval = info->manage_power(dev, 1);
913 		if (retval < 0) {
914 			retval = 0;
915 			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
916 		} else {
917 			usb_autopm_put_interface(dev->intf);
918 		}
919 	}
920 	return retval;
921 done:
922 	usb_autopm_put_interface(dev->intf);
923 done_nopm:
924 	return retval;
925 }
926 EXPORT_SYMBOL_GPL(usbnet_open);
927 
928 /*-------------------------------------------------------------------------*/
929 
930 /* ethtool methods; minidrivers may need to add some more, but
931  * they'll probably want to use this base set.
932  */
933 
934 int usbnet_get_settings (struct net_device *net, struct ethtool_cmd *cmd)
935 {
936 	struct usbnet *dev = netdev_priv(net);
937 
938 	if (!dev->mii.mdio_read)
939 		return -EOPNOTSUPP;
940 
941 	return mii_ethtool_gset(&dev->mii, cmd);
942 }
943 EXPORT_SYMBOL_GPL(usbnet_get_settings);
944 
945 int usbnet_set_settings (struct net_device *net, struct ethtool_cmd *cmd)
946 {
947 	struct usbnet *dev = netdev_priv(net);
948 	int retval;
949 
950 	if (!dev->mii.mdio_write)
951 		return -EOPNOTSUPP;
952 
953 	retval = mii_ethtool_sset(&dev->mii, cmd);
954 
955 	/* link speed/duplex might have changed */
956 	if (dev->driver_info->link_reset)
957 		dev->driver_info->link_reset(dev);
958 
959 	/* hard_mtu or rx_urb_size may change in link_reset() */
960 	usbnet_update_max_qlen(dev);
961 
962 	return retval;
963 
964 }
965 EXPORT_SYMBOL_GPL(usbnet_set_settings);
966 
967 u32 usbnet_get_link (struct net_device *net)
968 {
969 	struct usbnet *dev = netdev_priv(net);
970 
971 	/* If a check_connect is defined, return its result */
972 	if (dev->driver_info->check_connect)
973 		return dev->driver_info->check_connect (dev) == 0;
974 
975 	/* if the device has mii operations, use those */
976 	if (dev->mii.mdio_read)
977 		return mii_link_ok(&dev->mii);
978 
979 	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
980 	return ethtool_op_get_link(net);
981 }
982 EXPORT_SYMBOL_GPL(usbnet_get_link);
983 
984 int usbnet_nway_reset(struct net_device *net)
985 {
986 	struct usbnet *dev = netdev_priv(net);
987 
988 	if (!dev->mii.mdio_write)
989 		return -EOPNOTSUPP;
990 
991 	return mii_nway_restart(&dev->mii);
992 }
993 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
994 
995 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
996 {
997 	struct usbnet *dev = netdev_priv(net);
998 
999 	strlcpy (info->driver, dev->driver_name, sizeof info->driver);
1000 	strlcpy (info->version, DRIVER_VERSION, sizeof info->version);
1001 	strlcpy (info->fw_version, dev->driver_info->description,
1002 		sizeof info->fw_version);
1003 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
1004 }
1005 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
1006 
1007 u32 usbnet_get_msglevel (struct net_device *net)
1008 {
1009 	struct usbnet *dev = netdev_priv(net);
1010 
1011 	return dev->msg_enable;
1012 }
1013 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
1014 
1015 void usbnet_set_msglevel (struct net_device *net, u32 level)
1016 {
1017 	struct usbnet *dev = netdev_priv(net);
1018 
1019 	dev->msg_enable = level;
1020 }
1021 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
1022 
1023 /* drivers may override default ethtool_ops in their bind() routine */
1024 static const struct ethtool_ops usbnet_ethtool_ops = {
1025 	.get_settings		= usbnet_get_settings,
1026 	.set_settings		= usbnet_set_settings,
1027 	.get_link		= usbnet_get_link,
1028 	.nway_reset		= usbnet_nway_reset,
1029 	.get_drvinfo		= usbnet_get_drvinfo,
1030 	.get_msglevel		= usbnet_get_msglevel,
1031 	.set_msglevel		= usbnet_set_msglevel,
1032 	.get_ts_info		= ethtool_op_get_ts_info,
1033 };
1034 
1035 /*-------------------------------------------------------------------------*/
1036 
1037 static void __handle_link_change(struct usbnet *dev)
1038 {
1039 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
1040 		return;
1041 
1042 	if (!netif_carrier_ok(dev->net)) {
1043 		/* kill URBs for reading packets to save bus bandwidth */
1044 		unlink_urbs(dev, &dev->rxq);
1045 
1046 		/*
1047 		 * tx_timeout will unlink URBs for sending packets and
1048 		 * tx queue is stopped by netcore after link becomes off
1049 		 */
1050 	} else {
1051 		/* submitting URBs for reading packets */
1052 		tasklet_schedule(&dev->bh);
1053 	}
1054 
1055 	/* hard_mtu or rx_urb_size may change during link change */
1056 	usbnet_update_max_qlen(dev);
1057 
1058 	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
1059 }
1060 
1061 /* work that cannot be done in interrupt context uses keventd.
1062  *
1063  * NOTE:  with 2.5 we could do more of this using completion callbacks,
1064  * especially now that control transfers can be queued.
1065  */
1066 static void
1067 kevent (struct work_struct *work)
1068 {
1069 	struct usbnet		*dev =
1070 		container_of(work, struct usbnet, kevent);
1071 	int			status;
1072 
1073 	/* usb_clear_halt() needs a thread context */
1074 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
1075 		unlink_urbs (dev, &dev->txq);
1076 		status = usb_autopm_get_interface(dev->intf);
1077 		if (status < 0)
1078 			goto fail_pipe;
1079 		status = usb_clear_halt (dev->udev, dev->out);
1080 		usb_autopm_put_interface(dev->intf);
1081 		if (status < 0 &&
1082 		    status != -EPIPE &&
1083 		    status != -ESHUTDOWN) {
1084 			if (netif_msg_tx_err (dev))
1085 fail_pipe:
1086 				netdev_err(dev->net, "can't clear tx halt, status %d\n",
1087 					   status);
1088 		} else {
1089 			clear_bit (EVENT_TX_HALT, &dev->flags);
1090 			if (status != -ESHUTDOWN)
1091 				netif_wake_queue (dev->net);
1092 		}
1093 	}
1094 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
1095 		unlink_urbs (dev, &dev->rxq);
1096 		status = usb_autopm_get_interface(dev->intf);
1097 		if (status < 0)
1098 			goto fail_halt;
1099 		status = usb_clear_halt (dev->udev, dev->in);
1100 		usb_autopm_put_interface(dev->intf);
1101 		if (status < 0 &&
1102 		    status != -EPIPE &&
1103 		    status != -ESHUTDOWN) {
1104 			if (netif_msg_rx_err (dev))
1105 fail_halt:
1106 				netdev_err(dev->net, "can't clear rx halt, status %d\n",
1107 					   status);
1108 		} else {
1109 			clear_bit (EVENT_RX_HALT, &dev->flags);
1110 			tasklet_schedule (&dev->bh);
1111 		}
1112 	}
1113 
1114 	/* tasklet could resubmit itself forever if memory is tight */
1115 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
1116 		struct urb	*urb = NULL;
1117 		int resched = 1;
1118 
1119 		if (netif_running (dev->net))
1120 			urb = usb_alloc_urb (0, GFP_KERNEL);
1121 		else
1122 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1123 		if (urb != NULL) {
1124 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1125 			status = usb_autopm_get_interface(dev->intf);
1126 			if (status < 0) {
1127 				usb_free_urb(urb);
1128 				goto fail_lowmem;
1129 			}
1130 			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
1131 				resched = 0;
1132 			usb_autopm_put_interface(dev->intf);
1133 fail_lowmem:
1134 			if (resched)
1135 				tasklet_schedule (&dev->bh);
1136 		}
1137 	}
1138 
1139 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
1140 		struct driver_info	*info = dev->driver_info;
1141 		int			retval = 0;
1142 
1143 		clear_bit (EVENT_LINK_RESET, &dev->flags);
1144 		status = usb_autopm_get_interface(dev->intf);
1145 		if (status < 0)
1146 			goto skip_reset;
1147 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
1148 			usb_autopm_put_interface(dev->intf);
1149 skip_reset:
1150 			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
1151 				    retval,
1152 				    dev->udev->bus->bus_name,
1153 				    dev->udev->devpath,
1154 				    info->description);
1155 		} else {
1156 			usb_autopm_put_interface(dev->intf);
1157 		}
1158 
1159 		/* handle link change from link resetting */
1160 		__handle_link_change(dev);
1161 	}
1162 
1163 	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
1164 		__handle_link_change(dev);
1165 
1166 	if (dev->flags)
1167 		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
1168 }
1169 
1170 /*-------------------------------------------------------------------------*/
1171 
1172 static void tx_complete (struct urb *urb)
1173 {
1174 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
1175 	struct skb_data		*entry = (struct skb_data *) skb->cb;
1176 	struct usbnet		*dev = entry->dev;
1177 
1178 	if (urb->status == 0) {
1179 		if (!(dev->driver_info->flags & FLAG_MULTI_PACKET))
1180 			dev->net->stats.tx_packets++;
1181 		dev->net->stats.tx_bytes += entry->length;
1182 	} else {
1183 		dev->net->stats.tx_errors++;
1184 
1185 		switch (urb->status) {
1186 		case -EPIPE:
1187 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
1188 			break;
1189 
1190 		/* software-driven interface shutdown */
1191 		case -ECONNRESET:		// async unlink
1192 		case -ESHUTDOWN:		// hardware gone
1193 			break;
1194 
1195 		// like rx, tx gets controller i/o faults during khubd delays
1196 		// and so it uses the same throttling mechanism.
1197 		case -EPROTO:
1198 		case -ETIME:
1199 		case -EILSEQ:
1200 			usb_mark_last_busy(dev->udev);
1201 			if (!timer_pending (&dev->delay)) {
1202 				mod_timer (&dev->delay,
1203 					jiffies + THROTTLE_JIFFIES);
1204 				netif_dbg(dev, link, dev->net,
1205 					  "tx throttle %d\n", urb->status);
1206 			}
1207 			netif_stop_queue (dev->net);
1208 			break;
1209 		default:
1210 			netif_dbg(dev, tx_err, dev->net,
1211 				  "tx err %d\n", entry->urb->status);
1212 			break;
1213 		}
1214 	}
1215 
1216 	usb_autopm_put_interface_async(dev->intf);
1217 	(void) defer_bh(dev, skb, &dev->txq, tx_done);
1218 }
1219 
1220 /*-------------------------------------------------------------------------*/
1221 
1222 void usbnet_tx_timeout (struct net_device *net)
1223 {
1224 	struct usbnet		*dev = netdev_priv(net);
1225 
1226 	unlink_urbs (dev, &dev->txq);
1227 	tasklet_schedule (&dev->bh);
1228 
1229 	// FIXME: device recovery -- reset?
1230 }
1231 EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
1232 
1233 /*-------------------------------------------------------------------------*/
1234 
1235 static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
1236 {
1237 	unsigned num_sgs, total_len = 0;
1238 	int i, s = 0;
1239 
1240 	num_sgs = skb_shinfo(skb)->nr_frags + 1;
1241 	if (num_sgs == 1)
1242 		return 0;
1243 
1244 	/* reserve one for zero packet */
1245 	urb->sg = kmalloc((num_sgs + 1) * sizeof(struct scatterlist),
1246 			  GFP_ATOMIC);
1247 	if (!urb->sg)
1248 		return -ENOMEM;
1249 
1250 	urb->num_sgs = num_sgs;
1251 	sg_init_table(urb->sg, urb->num_sgs);
1252 
1253 	sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb));
1254 	total_len += skb_headlen(skb);
1255 
1256 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1257 		struct skb_frag_struct *f = &skb_shinfo(skb)->frags[i];
1258 
1259 		total_len += skb_frag_size(f);
1260 		sg_set_page(&urb->sg[i + s], f->page.p, f->size,
1261 				f->page_offset);
1262 	}
1263 	urb->transfer_buffer_length = total_len;
1264 
1265 	return 1;
1266 }
1267 
1268 netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
1269 				     struct net_device *net)
1270 {
1271 	struct usbnet		*dev = netdev_priv(net);
1272 	int			length;
1273 	struct urb		*urb = NULL;
1274 	struct skb_data		*entry;
1275 	struct driver_info	*info = dev->driver_info;
1276 	unsigned long		flags;
1277 	int retval;
1278 
1279 	if (skb)
1280 		skb_tx_timestamp(skb);
1281 
1282 	// some devices want funky USB-level framing, for
1283 	// win32 driver (usually) and/or hardware quirks
1284 	if (info->tx_fixup) {
1285 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
1286 		if (!skb) {
1287 			/* packet collected; minidriver waiting for more */
1288 			if (info->flags & FLAG_MULTI_PACKET)
1289 				goto not_drop;
1290 			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
1291 			goto drop;
1292 		}
1293 	}
1294 
1295 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
1296 		netif_dbg(dev, tx_err, dev->net, "no urb\n");
1297 		goto drop;
1298 	}
1299 
1300 	entry = (struct skb_data *) skb->cb;
1301 	entry->urb = urb;
1302 	entry->dev = dev;
1303 
1304 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
1305 			skb->data, skb->len, tx_complete, skb);
1306 	if (dev->can_dma_sg) {
1307 		if (build_dma_sg(skb, urb) < 0)
1308 			goto drop;
1309 	}
1310 	length = urb->transfer_buffer_length;
1311 
1312 	/* don't assume the hardware handles USB_ZERO_PACKET
1313 	 * NOTE:  strictly conforming cdc-ether devices should expect
1314 	 * the ZLP here, but ignore the one-byte packet.
1315 	 * NOTE2: CDC NCM specification is different from CDC ECM when
1316 	 * handling ZLP/short packets, so cdc_ncm driver will make short
1317 	 * packet itself if needed.
1318 	 */
1319 	if (length % dev->maxpacket == 0) {
1320 		if (!(info->flags & FLAG_SEND_ZLP)) {
1321 			if (!(info->flags & FLAG_MULTI_PACKET)) {
1322 				length++;
1323 				if (skb_tailroom(skb) && !urb->num_sgs) {
1324 					skb->data[skb->len] = 0;
1325 					__skb_put(skb, 1);
1326 				} else if (urb->num_sgs)
1327 					sg_set_buf(&urb->sg[urb->num_sgs++],
1328 							dev->padding_pkt, 1);
1329 			}
1330 		} else
1331 			urb->transfer_flags |= URB_ZERO_PACKET;
1332 	}
1333 	entry->length = urb->transfer_buffer_length = length;
1334 
1335 	spin_lock_irqsave(&dev->txq.lock, flags);
1336 	retval = usb_autopm_get_interface_async(dev->intf);
1337 	if (retval < 0) {
1338 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1339 		goto drop;
1340 	}
1341 
1342 #ifdef CONFIG_PM
1343 	/* if this triggers the device is still a sleep */
1344 	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
1345 		/* transmission will be done in resume */
1346 		usb_anchor_urb(urb, &dev->deferred);
1347 		/* no use to process more packets */
1348 		netif_stop_queue(net);
1349 		usb_put_urb(urb);
1350 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1351 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
1352 		goto deferred;
1353 	}
1354 #endif
1355 
1356 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
1357 	case -EPIPE:
1358 		netif_stop_queue (net);
1359 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
1360 		usb_autopm_put_interface_async(dev->intf);
1361 		break;
1362 	default:
1363 		usb_autopm_put_interface_async(dev->intf);
1364 		netif_dbg(dev, tx_err, dev->net,
1365 			  "tx: submit urb err %d\n", retval);
1366 		break;
1367 	case 0:
1368 		net->trans_start = jiffies;
1369 		__usbnet_queue_skb(&dev->txq, skb, tx_start);
1370 		if (dev->txq.qlen >= TX_QLEN (dev))
1371 			netif_stop_queue (net);
1372 	}
1373 	spin_unlock_irqrestore (&dev->txq.lock, flags);
1374 
1375 	if (retval) {
1376 		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
1377 drop:
1378 		dev->net->stats.tx_dropped++;
1379 not_drop:
1380 		if (skb)
1381 			dev_kfree_skb_any (skb);
1382 		if (urb) {
1383 			kfree(urb->sg);
1384 			usb_free_urb(urb);
1385 		}
1386 	} else
1387 		netif_dbg(dev, tx_queued, dev->net,
1388 			  "> tx, len %d, type 0x%x\n", length, skb->protocol);
1389 #ifdef CONFIG_PM
1390 deferred:
1391 #endif
1392 	return NETDEV_TX_OK;
1393 }
1394 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
1395 
1396 static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
1397 {
1398 	struct urb	*urb;
1399 	int		i;
1400 	int		ret = 0;
1401 
1402 	/* don't refill the queue all at once */
1403 	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
1404 		urb = usb_alloc_urb(0, flags);
1405 		if (urb != NULL) {
1406 			ret = rx_submit(dev, urb, flags);
1407 			if (ret)
1408 				goto err;
1409 		} else {
1410 			ret = -ENOMEM;
1411 			goto err;
1412 		}
1413 	}
1414 err:
1415 	return ret;
1416 }
1417 
1418 /*-------------------------------------------------------------------------*/
1419 
1420 // tasklet (work deferred from completions, in_irq) or timer
1421 
1422 static void usbnet_bh (unsigned long param)
1423 {
1424 	struct usbnet		*dev = (struct usbnet *) param;
1425 	struct sk_buff		*skb;
1426 	struct skb_data		*entry;
1427 
1428 	while ((skb = skb_dequeue (&dev->done))) {
1429 		entry = (struct skb_data *) skb->cb;
1430 		switch (entry->state) {
1431 		case rx_done:
1432 			entry->state = rx_cleanup;
1433 			rx_process (dev, skb);
1434 			continue;
1435 		case tx_done:
1436 			kfree(entry->urb->sg);
1437 		case rx_cleanup:
1438 			usb_free_urb (entry->urb);
1439 			dev_kfree_skb (skb);
1440 			continue;
1441 		default:
1442 			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
1443 		}
1444 	}
1445 
1446 	/* restart RX again after disabling due to high error rate */
1447 	clear_bit(EVENT_RX_KILL, &dev->flags);
1448 
1449 	// waiting for all pending urbs to complete?
1450 	if (dev->wait) {
1451 		if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
1452 			wake_up (dev->wait);
1453 		}
1454 
1455 	// or are we maybe short a few urbs?
1456 	} else if (netif_running (dev->net) &&
1457 		   netif_device_present (dev->net) &&
1458 		   netif_carrier_ok(dev->net) &&
1459 		   !timer_pending (&dev->delay) &&
1460 		   !test_bit (EVENT_RX_HALT, &dev->flags)) {
1461 		int	temp = dev->rxq.qlen;
1462 
1463 		if (temp < RX_QLEN(dev)) {
1464 			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
1465 				return;
1466 			if (temp != dev->rxq.qlen)
1467 				netif_dbg(dev, link, dev->net,
1468 					  "rxqlen %d --> %d\n",
1469 					  temp, dev->rxq.qlen);
1470 			if (dev->rxq.qlen < RX_QLEN(dev))
1471 				tasklet_schedule (&dev->bh);
1472 		}
1473 		if (dev->txq.qlen < TX_QLEN (dev))
1474 			netif_wake_queue (dev->net);
1475 	}
1476 }
1477 
1478 
1479 /*-------------------------------------------------------------------------
1480  *
1481  * USB Device Driver support
1482  *
1483  *-------------------------------------------------------------------------*/
1484 
1485 // precondition: never called in_interrupt
1486 
1487 void usbnet_disconnect (struct usb_interface *intf)
1488 {
1489 	struct usbnet		*dev;
1490 	struct usb_device	*xdev;
1491 	struct net_device	*net;
1492 
1493 	dev = usb_get_intfdata(intf);
1494 	usb_set_intfdata(intf, NULL);
1495 	if (!dev)
1496 		return;
1497 
1498 	xdev = interface_to_usbdev (intf);
1499 
1500 	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
1501 		   intf->dev.driver->name,
1502 		   xdev->bus->bus_name, xdev->devpath,
1503 		   dev->driver_info->description);
1504 
1505 	net = dev->net;
1506 	unregister_netdev (net);
1507 
1508 	cancel_work_sync(&dev->kevent);
1509 
1510 	usb_scuttle_anchored_urbs(&dev->deferred);
1511 
1512 	if (dev->driver_info->unbind)
1513 		dev->driver_info->unbind (dev, intf);
1514 
1515 	usb_kill_urb(dev->interrupt);
1516 	usb_free_urb(dev->interrupt);
1517 	kfree(dev->padding_pkt);
1518 
1519 	free_netdev(net);
1520 }
1521 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1522 
1523 static const struct net_device_ops usbnet_netdev_ops = {
1524 	.ndo_open		= usbnet_open,
1525 	.ndo_stop		= usbnet_stop,
1526 	.ndo_start_xmit		= usbnet_start_xmit,
1527 	.ndo_tx_timeout		= usbnet_tx_timeout,
1528 	.ndo_change_mtu		= usbnet_change_mtu,
1529 	.ndo_set_mac_address 	= eth_mac_addr,
1530 	.ndo_validate_addr	= eth_validate_addr,
1531 };
1532 
1533 /*-------------------------------------------------------------------------*/
1534 
1535 // precondition: never called in_interrupt
1536 
1537 static struct device_type wlan_type = {
1538 	.name	= "wlan",
1539 };
1540 
1541 static struct device_type wwan_type = {
1542 	.name	= "wwan",
1543 };
1544 
1545 int
1546 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1547 {
1548 	struct usbnet			*dev;
1549 	struct net_device		*net;
1550 	struct usb_host_interface	*interface;
1551 	struct driver_info		*info;
1552 	struct usb_device		*xdev;
1553 	int				status;
1554 	const char			*name;
1555 	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
1556 
1557 	/* usbnet already took usb runtime pm, so have to enable the feature
1558 	 * for usb interface, otherwise usb_autopm_get_interface may return
1559 	 * failure if RUNTIME_PM is enabled.
1560 	 */
1561 	if (!driver->supports_autosuspend) {
1562 		driver->supports_autosuspend = 1;
1563 		pm_runtime_enable(&udev->dev);
1564 	}
1565 
1566 	name = udev->dev.driver->name;
1567 	info = (struct driver_info *) prod->driver_info;
1568 	if (!info) {
1569 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1570 		return -ENODEV;
1571 	}
1572 	xdev = interface_to_usbdev (udev);
1573 	interface = udev->cur_altsetting;
1574 
1575 	status = -ENOMEM;
1576 
1577 	// set up our own records
1578 	net = alloc_etherdev(sizeof(*dev));
1579 	if (!net)
1580 		goto out;
1581 
1582 	/* netdev_printk() needs this so do it as early as possible */
1583 	SET_NETDEV_DEV(net, &udev->dev);
1584 
1585 	dev = netdev_priv(net);
1586 	dev->udev = xdev;
1587 	dev->intf = udev;
1588 	dev->driver_info = info;
1589 	dev->driver_name = name;
1590 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1591 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1592 	skb_queue_head_init (&dev->rxq);
1593 	skb_queue_head_init (&dev->txq);
1594 	skb_queue_head_init (&dev->done);
1595 	skb_queue_head_init(&dev->rxq_pause);
1596 	dev->bh.func = usbnet_bh;
1597 	dev->bh.data = (unsigned long) dev;
1598 	INIT_WORK (&dev->kevent, kevent);
1599 	init_usb_anchor(&dev->deferred);
1600 	dev->delay.function = usbnet_bh;
1601 	dev->delay.data = (unsigned long) dev;
1602 	init_timer (&dev->delay);
1603 	mutex_init (&dev->phy_mutex);
1604 	mutex_init(&dev->interrupt_mutex);
1605 	dev->interrupt_count = 0;
1606 
1607 	dev->net = net;
1608 	strcpy (net->name, "usb%d");
1609 	memcpy (net->dev_addr, node_id, sizeof node_id);
1610 
1611 	/* rx and tx sides can use different message sizes;
1612 	 * bind() should set rx_urb_size in that case.
1613 	 */
1614 	dev->hard_mtu = net->mtu + net->hard_header_len;
1615 #if 0
1616 // dma_supported() is deeply broken on almost all architectures
1617 	// possible with some EHCI controllers
1618 	if (dma_supported (&udev->dev, DMA_BIT_MASK(64)))
1619 		net->features |= NETIF_F_HIGHDMA;
1620 #endif
1621 
1622 	net->netdev_ops = &usbnet_netdev_ops;
1623 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1624 	net->ethtool_ops = &usbnet_ethtool_ops;
1625 
1626 	// allow device-specific bind/init procedures
1627 	// NOTE net->name still not usable ...
1628 	if (info->bind) {
1629 		status = info->bind (dev, udev);
1630 		if (status < 0)
1631 			goto out1;
1632 
1633 		// heuristic:  "usb%d" for links we know are two-host,
1634 		// else "eth%d" when there's reasonable doubt.  userspace
1635 		// can rename the link if it knows better.
1636 		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
1637 		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
1638 		     (net->dev_addr [0] & 0x02) == 0))
1639 			strcpy (net->name, "eth%d");
1640 		/* WLAN devices should always be named "wlan%d" */
1641 		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1642 			strcpy(net->name, "wlan%d");
1643 		/* WWAN devices should always be named "wwan%d" */
1644 		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1645 			strcpy(net->name, "wwan%d");
1646 
1647 		/* devices that cannot do ARP */
1648 		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
1649 			net->flags |= IFF_NOARP;
1650 
1651 		/* maybe the remote can't receive an Ethernet MTU */
1652 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1653 			net->mtu = dev->hard_mtu - net->hard_header_len;
1654 	} else if (!info->in || !info->out)
1655 		status = usbnet_get_endpoints (dev, udev);
1656 	else {
1657 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1658 		dev->out = usb_sndbulkpipe (xdev, info->out);
1659 		if (!(info->flags & FLAG_NO_SETINT))
1660 			status = usb_set_interface (xdev,
1661 				interface->desc.bInterfaceNumber,
1662 				interface->desc.bAlternateSetting);
1663 		else
1664 			status = 0;
1665 
1666 	}
1667 	if (status >= 0 && dev->status)
1668 		status = init_status (dev, udev);
1669 	if (status < 0)
1670 		goto out3;
1671 
1672 	if (!dev->rx_urb_size)
1673 		dev->rx_urb_size = dev->hard_mtu;
1674 	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
1675 
1676 	/* let userspace know we have a random address */
1677 	if (ether_addr_equal(net->dev_addr, node_id))
1678 		net->addr_assign_type = NET_ADDR_RANDOM;
1679 
1680 	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1681 		SET_NETDEV_DEVTYPE(net, &wlan_type);
1682 	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1683 		SET_NETDEV_DEVTYPE(net, &wwan_type);
1684 
1685 	/* initialize max rx_qlen and tx_qlen */
1686 	usbnet_update_max_qlen(dev);
1687 
1688 	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
1689 		!(info->flags & FLAG_MULTI_PACKET)) {
1690 		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
1691 		if (!dev->padding_pkt)
1692 			goto out4;
1693 	}
1694 
1695 	status = register_netdev (net);
1696 	if (status)
1697 		goto out5;
1698 	netif_info(dev, probe, dev->net,
1699 		   "register '%s' at usb-%s-%s, %s, %pM\n",
1700 		   udev->dev.driver->name,
1701 		   xdev->bus->bus_name, xdev->devpath,
1702 		   dev->driver_info->description,
1703 		   net->dev_addr);
1704 
1705 	// ok, it's ready to go.
1706 	usb_set_intfdata (udev, dev);
1707 
1708 	netif_device_attach (net);
1709 
1710 	if (dev->driver_info->flags & FLAG_LINK_INTR)
1711 		usbnet_link_change(dev, 0, 0);
1712 
1713 	return 0;
1714 
1715 out5:
1716 	kfree(dev->padding_pkt);
1717 out4:
1718 	usb_free_urb(dev->interrupt);
1719 out3:
1720 	if (info->unbind)
1721 		info->unbind (dev, udev);
1722 out1:
1723 	free_netdev(net);
1724 out:
1725 	return status;
1726 }
1727 EXPORT_SYMBOL_GPL(usbnet_probe);
1728 
1729 /*-------------------------------------------------------------------------*/
1730 
1731 /*
1732  * suspend the whole driver as soon as the first interface is suspended
1733  * resume only when the last interface is resumed
1734  */
1735 
1736 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1737 {
1738 	struct usbnet		*dev = usb_get_intfdata(intf);
1739 
1740 	if (!dev->suspend_count++) {
1741 		spin_lock_irq(&dev->txq.lock);
1742 		/* don't autosuspend while transmitting */
1743 		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
1744 			dev->suspend_count--;
1745 			spin_unlock_irq(&dev->txq.lock);
1746 			return -EBUSY;
1747 		} else {
1748 			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
1749 			spin_unlock_irq(&dev->txq.lock);
1750 		}
1751 		/*
1752 		 * accelerate emptying of the rx and queues, to avoid
1753 		 * having everything error out.
1754 		 */
1755 		netif_device_detach (dev->net);
1756 		usbnet_terminate_urbs(dev);
1757 		__usbnet_status_stop_force(dev);
1758 
1759 		/*
1760 		 * reattach so runtime management can use and
1761 		 * wake the device
1762 		 */
1763 		netif_device_attach (dev->net);
1764 	}
1765 	return 0;
1766 }
1767 EXPORT_SYMBOL_GPL(usbnet_suspend);
1768 
1769 int usbnet_resume (struct usb_interface *intf)
1770 {
1771 	struct usbnet		*dev = usb_get_intfdata(intf);
1772 	struct sk_buff          *skb;
1773 	struct urb              *res;
1774 	int                     retval;
1775 
1776 	if (!--dev->suspend_count) {
1777 		/* resume interrupt URB if it was previously submitted */
1778 		__usbnet_status_start_force(dev, GFP_NOIO);
1779 
1780 		spin_lock_irq(&dev->txq.lock);
1781 		while ((res = usb_get_from_anchor(&dev->deferred))) {
1782 
1783 			skb = (struct sk_buff *)res->context;
1784 			retval = usb_submit_urb(res, GFP_ATOMIC);
1785 			if (retval < 0) {
1786 				dev_kfree_skb_any(skb);
1787 				kfree(res->sg);
1788 				usb_free_urb(res);
1789 				usb_autopm_put_interface_async(dev->intf);
1790 			} else {
1791 				dev->net->trans_start = jiffies;
1792 				__skb_queue_tail(&dev->txq, skb);
1793 			}
1794 		}
1795 
1796 		smp_mb();
1797 		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
1798 		spin_unlock_irq(&dev->txq.lock);
1799 
1800 		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
1801 			/* handle remote wakeup ASAP */
1802 			if (!dev->wait &&
1803 				netif_device_present(dev->net) &&
1804 				!timer_pending(&dev->delay) &&
1805 				!test_bit(EVENT_RX_HALT, &dev->flags))
1806 					rx_alloc_submit(dev, GFP_NOIO);
1807 
1808 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
1809 				netif_tx_wake_all_queues(dev->net);
1810 			tasklet_schedule (&dev->bh);
1811 		}
1812 	}
1813 
1814 	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
1815 		usb_autopm_get_interface_no_resume(intf);
1816 
1817 	return 0;
1818 }
1819 EXPORT_SYMBOL_GPL(usbnet_resume);
1820 
1821 /*
1822  * Either a subdriver implements manage_power, then it is assumed to always
1823  * be ready to be suspended or it reports the readiness to be suspended
1824  * explicitly
1825  */
1826 void usbnet_device_suggests_idle(struct usbnet *dev)
1827 {
1828 	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
1829 		dev->intf->needs_remote_wakeup = 1;
1830 		usb_autopm_put_interface_async(dev->intf);
1831 	}
1832 }
1833 EXPORT_SYMBOL(usbnet_device_suggests_idle);
1834 
1835 /*
1836  * For devices that can do without special commands
1837  */
1838 int usbnet_manage_power(struct usbnet *dev, int on)
1839 {
1840 	dev->intf->needs_remote_wakeup = on;
1841 	return 0;
1842 }
1843 EXPORT_SYMBOL(usbnet_manage_power);
1844 
1845 void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
1846 {
1847 	/* update link after link is reseted */
1848 	if (link && !need_reset)
1849 		netif_carrier_on(dev->net);
1850 	else
1851 		netif_carrier_off(dev->net);
1852 
1853 	if (need_reset && link)
1854 		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
1855 	else
1856 		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
1857 }
1858 EXPORT_SYMBOL(usbnet_link_change);
1859 
1860 /*-------------------------------------------------------------------------*/
1861 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1862 			     u16 value, u16 index, void *data, u16 size)
1863 {
1864 	void *buf = NULL;
1865 	int err = -ENOMEM;
1866 
1867 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
1868 		   " value=0x%04x index=0x%04x size=%d\n",
1869 		   cmd, reqtype, value, index, size);
1870 
1871 	if (data) {
1872 		buf = kmalloc(size, GFP_KERNEL);
1873 		if (!buf)
1874 			goto out;
1875 	}
1876 
1877 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
1878 			      cmd, reqtype, value, index, buf, size,
1879 			      USB_CTRL_GET_TIMEOUT);
1880 	if (err > 0 && err <= size)
1881 		memcpy(data, buf, err);
1882 	kfree(buf);
1883 out:
1884 	return err;
1885 }
1886 
1887 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1888 			      u16 value, u16 index, const void *data,
1889 			      u16 size)
1890 {
1891 	void *buf = NULL;
1892 	int err = -ENOMEM;
1893 
1894 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1895 		   " value=0x%04x index=0x%04x size=%d\n",
1896 		   cmd, reqtype, value, index, size);
1897 
1898 	if (data) {
1899 		buf = kmemdup(data, size, GFP_KERNEL);
1900 		if (!buf)
1901 			goto out;
1902 	}
1903 
1904 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1905 			      cmd, reqtype, value, index, buf, size,
1906 			      USB_CTRL_SET_TIMEOUT);
1907 	kfree(buf);
1908 
1909 out:
1910 	return err;
1911 }
1912 
1913 /*
1914  * The function can't be called inside suspend/resume callback,
1915  * otherwise deadlock will be caused.
1916  */
1917 int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1918 		    u16 value, u16 index, void *data, u16 size)
1919 {
1920 	int ret;
1921 
1922 	if (usb_autopm_get_interface(dev->intf) < 0)
1923 		return -ENODEV;
1924 	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1925 				data, size);
1926 	usb_autopm_put_interface(dev->intf);
1927 	return ret;
1928 }
1929 EXPORT_SYMBOL_GPL(usbnet_read_cmd);
1930 
1931 /*
1932  * The function can't be called inside suspend/resume callback,
1933  * otherwise deadlock will be caused.
1934  */
1935 int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1936 		     u16 value, u16 index, const void *data, u16 size)
1937 {
1938 	int ret;
1939 
1940 	if (usb_autopm_get_interface(dev->intf) < 0)
1941 		return -ENODEV;
1942 	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1943 				 data, size);
1944 	usb_autopm_put_interface(dev->intf);
1945 	return ret;
1946 }
1947 EXPORT_SYMBOL_GPL(usbnet_write_cmd);
1948 
1949 /*
1950  * The function can be called inside suspend/resume callback safely
1951  * and should only be called by suspend/resume callback generally.
1952  */
1953 int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1954 			  u16 value, u16 index, void *data, u16 size)
1955 {
1956 	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1957 				 data, size);
1958 }
1959 EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
1960 
1961 /*
1962  * The function can be called inside suspend/resume callback safely
1963  * and should only be called by suspend/resume callback generally.
1964  */
1965 int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1966 			  u16 value, u16 index, const void *data,
1967 			  u16 size)
1968 {
1969 	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1970 				  data, size);
1971 }
1972 EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
1973 
1974 static void usbnet_async_cmd_cb(struct urb *urb)
1975 {
1976 	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
1977 	int status = urb->status;
1978 
1979 	if (status < 0)
1980 		dev_dbg(&urb->dev->dev, "%s failed with %d",
1981 			__func__, status);
1982 
1983 	kfree(req);
1984 	usb_free_urb(urb);
1985 }
1986 
1987 /*
1988  * The caller must make sure that device can't be put into suspend
1989  * state until the control URB completes.
1990  */
1991 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
1992 			   u16 value, u16 index, const void *data, u16 size)
1993 {
1994 	struct usb_ctrlrequest *req = NULL;
1995 	struct urb *urb;
1996 	int err = -ENOMEM;
1997 	void *buf = NULL;
1998 
1999 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
2000 		   " value=0x%04x index=0x%04x size=%d\n",
2001 		   cmd, reqtype, value, index, size);
2002 
2003 	urb = usb_alloc_urb(0, GFP_ATOMIC);
2004 	if (!urb) {
2005 		netdev_err(dev->net, "Error allocating URB in"
2006 			   " %s!\n", __func__);
2007 		goto fail;
2008 	}
2009 
2010 	if (data) {
2011 		buf = kmemdup(data, size, GFP_ATOMIC);
2012 		if (!buf) {
2013 			netdev_err(dev->net, "Error allocating buffer"
2014 				   " in %s!\n", __func__);
2015 			goto fail_free;
2016 		}
2017 	}
2018 
2019 	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
2020 	if (!req)
2021 		goto fail_free_buf;
2022 
2023 	req->bRequestType = reqtype;
2024 	req->bRequest = cmd;
2025 	req->wValue = cpu_to_le16(value);
2026 	req->wIndex = cpu_to_le16(index);
2027 	req->wLength = cpu_to_le16(size);
2028 
2029 	usb_fill_control_urb(urb, dev->udev,
2030 			     usb_sndctrlpipe(dev->udev, 0),
2031 			     (void *)req, buf, size,
2032 			     usbnet_async_cmd_cb, req);
2033 	urb->transfer_flags |= URB_FREE_BUFFER;
2034 
2035 	err = usb_submit_urb(urb, GFP_ATOMIC);
2036 	if (err < 0) {
2037 		netdev_err(dev->net, "Error submitting the control"
2038 			   " message: status=%d\n", err);
2039 		goto fail_free;
2040 	}
2041 	return 0;
2042 
2043 fail_free_buf:
2044 	kfree(buf);
2045 fail_free:
2046 	kfree(req);
2047 	usb_free_urb(urb);
2048 fail:
2049 	return err;
2050 
2051 }
2052 EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
2053 /*-------------------------------------------------------------------------*/
2054 
2055 static int __init usbnet_init(void)
2056 {
2057 	/* Compiler should optimize this out. */
2058 	BUILD_BUG_ON(
2059 		FIELD_SIZEOF(struct sk_buff, cb) < sizeof(struct skb_data));
2060 
2061 	eth_random_addr(node_id);
2062 	return 0;
2063 }
2064 module_init(usbnet_init);
2065 
2066 static void __exit usbnet_exit(void)
2067 {
2068 }
2069 module_exit(usbnet_exit);
2070 
2071 MODULE_AUTHOR("David Brownell");
2072 MODULE_DESCRIPTION("USB network driver framework");
2073 MODULE_LICENSE("GPL");
2074