summaryrefslogtreecommitdiff
path: root/drivers/usb/gadget/u_ether.c
blob: 6e6f87656e7b0f5795caa17f387aa6cf89de2d41 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
/*
 * u_ether.c -- Ethernet-over-USB link layer utilities for Gadget stack
 *
 * Copyright (C) 2003-2005,2008 David Brownell
 * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
 * Copyright (C) 2008 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

/* #define VERBOSE_DEBUG */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/device.h>
#include <linux/ctype.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/if_vlan.h>

#include "u_ether.h"


/*
 * This component encapsulates the Ethernet link glue needed to provide
 * one (!) network link through the USB gadget stack, normally "usb0".
 *
 * The control and data models are handled by the function driver which
 * connects to this code; such as CDC Ethernet (ECM or EEM),
 * "CDC Subset", or RNDIS.  That includes all descriptor and endpoint
 * management.
 *
 * Link level addressing is handled by this component using module
 * parameters; if no such parameters are provided, random link level
 * addresses are used.  Each end of the link uses one address.  The
 * host end address is exported in various ways, and is often recorded
 * in configuration databases.
 *
 * The driver which assembles each configuration using such a link is
 * responsible for ensuring that each configuration includes at most one
 * instance of is network link.  (The network layer provides ways for
 * this single "physical" link to be used by multiple virtual links.)
 */

#define UETH__VERSION	"29-May-2008"

struct eth_dev {
	/* lock is held while accessing port_usb
	 */
	spinlock_t		lock;
	struct gether		*port_usb;

	struct net_device	*net;
	struct usb_gadget	*gadget;

	spinlock_t		req_lock;	/* guard {rx,tx}_reqs */
	struct list_head	tx_reqs, rx_reqs;
	atomic_t		tx_qlen;

	struct sk_buff_head	rx_frames;

	unsigned		qmult;

	unsigned		header_len;
	struct sk_buff		*(*wrap)(struct gether *, struct sk_buff *skb);
	int			(*unwrap)(struct gether *,
						struct sk_buff *skb,
						struct sk_buff_head *list);

	struct work_struct	work;

	unsigned long		todo;
#define	WORK_RX_MEMORY		0

	bool			zlp;
	u8			host_mac[ETH_ALEN];
	u8			dev_mac[ETH_ALEN];
};

/*-------------------------------------------------------------------------*/

#define RX_EXTRA	20	/* bytes guarding against rx overflows */

#define DEFAULT_QLEN	2	/* double buffering by default */

/* for dual-speed hardware, use deeper queues at high/super speed */
static inline int qlen(struct usb_gadget *gadget, unsigned qmult)
{
	if (gadget_is_dualspeed(gadget) && (gadget->speed == USB_SPEED_HIGH ||
					    gadget->speed == USB_SPEED_SUPER))
		return qmult * DEFAULT_QLEN;
	else
		return DEFAULT_QLEN;
}

/*-------------------------------------------------------------------------*/

/* REVISIT there must be a better way than having two sets
 * of debug calls ...
 */

#undef DBG
#undef VDBG
#undef ERROR
#undef INFO

#define xprintk(d, level, fmt, args...) \
	printk(level "%s: " fmt , (d)->net->name , ## args)

#ifdef DEBUG
#undef DEBUG
#define DBG(dev, fmt, args...) \
	xprintk(dev , KERN_DEBUG , fmt , ## args)
#else
#define DBG(dev, fmt, args...) \
	do { } while (0)
#endif /* DEBUG */

#ifdef VERBOSE_DEBUG
#define VDBG	DBG
#else
#define VDBG(dev, fmt, args...) \
	do { } while (0)
#endif /* DEBUG */

#define ERROR(dev, fmt, args...) \
	xprintk(dev , KERN_ERR , fmt , ## args)
#define INFO(dev, fmt, args...) \
	xprintk(dev , KERN_INFO , fmt , ## args)

/*-------------------------------------------------------------------------*/

/* NETWORK DRIVER HOOKUP (to the layer above this driver) */

static int ueth_change_mtu(struct net_device *net, int new_mtu)
{
	struct eth_dev	*dev = netdev_priv(net);
	unsigned long	flags;
	int		status = 0;

	/* don't change MTU on "live" link (peer won't know) */
	spin_lock_irqsave(&dev->lock, flags);
	if (dev->port_usb)
		status = -EBUSY;
	else if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
		status = -ERANGE;
	else
		net->mtu = new_mtu;
	spin_unlock_irqrestore(&dev->lock, flags);

	return status;
}

static void eth_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *p)
{
	struct eth_dev *dev = netdev_priv(net);

	strlcpy(p->driver, "g_ether", sizeof(p->driver));
	strlcpy(p->version, UETH__VERSION, sizeof(p->version));
	strlcpy(p->fw_version, dev->gadget->name, sizeof(p->fw_version));
	strlcpy(p->bus_info, dev_name(&dev->gadget->dev), sizeof(p->bus_info));
}

/* REVISIT can also support:
 *   - WOL (by tracking suspends and issuing remote wakeup)
 *   - msglevel (implies updated messaging)
 *   - ... probably more ethtool ops
 */

static const struct ethtool_ops ops = {
	.get_drvinfo = eth_get_drvinfo,
	.get_link = ethtool_op_get_link,
};

static void defer_kevent(struct eth_dev *dev, int flag)
{
	if (test_and_set_bit(flag, &dev->todo))
		return;
	if (!schedule_work(&dev->work))
		ERROR(dev, "kevent %d may have been dropped\n", flag);
	else
		DBG(dev, "kevent %d scheduled\n", flag);
}

static void rx_complete(struct usb_ep *ep, struct usb_request *req);

static int
rx_submit(struct eth_dev *dev, struct usb_request *req, gfp_t gfp_flags)
{
	struct sk_buff	*skb;
	int		retval = -ENOMEM;
	size_t		size = 0;
	struct usb_ep	*out;
	unsigned long	flags;

	spin_lock_irqsave(&dev->lock, flags);
	if (dev->port_usb)
		out = dev->port_usb->out_ep;
	else
		out = NULL;
	spin_unlock_irqrestore(&dev->lock, flags);

	if (!out)
		return -ENOTCONN;


	/* Padding up to RX_EXTRA handles minor disagreements with host.
	 * Normally we use the USB "terminate on short read" convention;
	 * so allow up to (N*maxpacket), since that memory is normally
	 * already allocated.  Some hardware doesn't deal well with short
	 * reads (e.g. DMA must be N*maxpacket), so for now don't trim a
	 * byte off the end (to force hardware errors on overflow).
	 *
	 * RNDIS uses internal framing, and explicitly allows senders to
	 * pad to end-of-packet.  That's potentially nice for speed, but
	 * means receivers can't recover lost synch on their own (because
	 * new packets don't only start after a short RX).
	 */
	size += sizeof(struct ethhdr) + dev->net->mtu + RX_EXTRA;
	size += dev->port_usb->header_len;
	size += out->maxpacket - 1;
	size -= size % out->maxpacket;

	if (dev->port_usb->is_fixed)
		size = max_t(size_t, size, dev->port_usb->fixed_out_len);

	skb = alloc_skb(size + NET_IP_ALIGN, gfp_flags);
	if (skb == NULL) {
		DBG(dev, "no rx skb\n");
		goto enomem;
	}

	/* Some platforms perform better when IP packets are aligned,
	 * but on at least one, checksumming fails otherwise.  Note:
	 * RNDIS headers involve variable numbers of LE32 values.
	 */
	skb_reserve(skb, NET_IP_ALIGN);

	req->buf = skb->data;
	req->length = size;
	req->complete = rx_complete;
	req->context = skb;

	retval = usb_ep_queue(out, req, gfp_flags);
	if (retval == -ENOMEM)
enomem:
		defer_kevent(dev, WORK_RX_MEMORY);
	if (retval) {
		DBG(dev, "rx submit --> %d\n", retval);
		if (skb)
			dev_kfree_skb_any(skb);
		spin_lock_irqsave(&dev->req_lock, flags);
		list_add(&req->list, &dev->rx_reqs);
		spin_unlock_irqrestore(&dev->req_lock, flags);
	}
	return retval;
}

static void rx_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct sk_buff	*skb = req->context, *skb2;
	struct eth_dev	*dev = ep->driver_data;
	int		status = req->status;

	switch (status) {

	/* normal completion */
	case 0:
		skb_put(skb, req->actual);

		if (dev->unwrap) {
			unsigned long	flags;

			spin_lock_irqsave(&dev->lock, flags);
			if (dev->port_usb) {
				status = dev->unwrap(dev->port_usb,
							skb,
							&dev->rx_frames);
			} else {
				dev_kfree_skb_any(skb);
				status = -ENOTCONN;
			}
			spin_unlock_irqrestore(&dev->lock, flags);
		} else {
			skb_queue_tail(&dev->rx_frames, skb);
		}
		skb = NULL;

		skb2 = skb_dequeue(&dev->rx_frames);
		while (skb2) {
			if (status < 0
					|| ETH_HLEN > skb2->len
					|| skb2->len > VLAN_ETH_FRAME_LEN) {
				dev->net->stats.rx_errors++;
				dev->net->stats.rx_length_errors++;
				DBG(dev, "rx length %d\n", skb2->len);
				dev_kfree_skb_any(skb2);
				goto next_frame;
			}
			skb2->protocol = eth_type_trans(skb2, dev->net);
			dev->net->stats.rx_packets++;
			dev->net->stats.rx_bytes += skb2->len;

			/* no buffer copies needed, unless hardware can't
			 * use skb buffers.
			 */
			status = netif_rx(skb2);
next_frame:
			skb2 = skb_dequeue(&dev->rx_frames);
		}
		break;

	/* software-driven interface shutdown */
	case -ECONNRESET:		/* unlink */
	case -ESHUTDOWN:		/* disconnect etc */
		VDBG(dev, "rx shutdown, code %d\n", status);
		goto quiesce;

	/* for hardware automagic (such as pxa) */
	case -ECONNABORTED:		/* endpoint reset */
		DBG(dev, "rx %s reset\n", ep->name);
		defer_kevent(dev, WORK_RX_MEMORY);
quiesce:
		dev_kfree_skb_any(skb);
		goto clean;

	/* data overrun */
	case -EOVERFLOW:
		dev->net->stats.rx_over_errors++;
		/* FALLTHROUGH */

	default:
		dev->net->stats.rx_errors++;
		DBG(dev, "rx status %d\n", status);
		break;
	}

	if (skb)
		dev_kfree_skb_any(skb);
	if (!netif_running(dev->net)) {
clean:
		spin_lock(&dev->req_lock);
		list_add(&req->list, &dev->rx_reqs);
		spin_unlock(&dev->req_lock);
		req = NULL;
	}
	if (req)
		rx_submit(dev, req, GFP_ATOMIC);
}

static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
{
	unsigned		i;
	struct usb_request	*req;

	if (!n)
		return -ENOMEM;

	/* queue/recycle up to N requests */
	i = n;
	list_for_each_entry(req, list, list) {
		if (i-- == 0)
			goto extra;
	}
	while (i--) {
		req = usb_ep_alloc_request(ep, GFP_ATOMIC);
		if (!req)
			return list_empty(list) ? -ENOMEM : 0;
		list_add(&req->list, list);
	}
	return 0;

extra:
	/* free extras */
	for (;;) {
		struct list_head	*next;

		next = req->list.next;
		list_del(&req->list);
		usb_ep_free_request(ep, req);

		if (next == list)
			break;

		req = container_of(next, struct usb_request, list);
	}
	return 0;
}

static int alloc_requests(struct eth_dev *dev, struct gether *link, unsigned n)
{
	int	status;

	spin_lock(&dev->req_lock);
	status = prealloc(&dev->tx_reqs, link->in_ep, n);
	if (status < 0)
		goto fail;
	status = prealloc(&dev->rx_reqs, link->out_ep, n);
	if (status < 0)
		goto fail;
	goto done;
fail:
	DBG(dev, "can't alloc requests\n");
done:
	spin_unlock(&dev->req_lock);
	return status;
}

static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
{
	struct usb_request	*req;
	unsigned long		flags;

	/* fill unused rxq slots with some skb */
	spin_lock_irqsave(&dev->req_lock, flags);
	while (!list_empty(&dev->rx_reqs)) {
		req = container_of(dev->rx_reqs.next,
				struct usb_request, list);
		list_del_init(&req->list);
		spin_unlock_irqrestore(&dev->req_lock, flags);

		if (rx_submit(dev, req, gfp_flags) < 0) {
			defer_kevent(dev, WORK_RX_MEMORY);
			return;
		}

		spin_lock_irqsave(&dev->req_lock, flags);
	}
	spin_unlock_irqrestore(&dev->req_lock, flags);
}

static void eth_work(struct work_struct *work)
{
	struct eth_dev	*dev = container_of(work, struct eth_dev, work);

	if (test_and_clear_bit(WORK_RX_MEMORY, &dev->todo)) {
		if (netif_running(dev->net))
			rx_fill(dev, GFP_KERNEL);
	}

	if (dev->todo)
		DBG(dev, "work done, flags = 0x%lx\n", dev->todo);
}

static void tx_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct sk_buff	*skb = req->context;
	struct eth_dev	*dev = ep->driver_data;

	switch (req->status) {
	default:
		dev->net->stats.tx_errors++;
		VDBG(dev, "tx err %d\n", req->status);
		/* FALLTHROUGH */
	case -ECONNRESET:		/* unlink */
	case -ESHUTDOWN:		/* disconnect etc */
		break;
	case 0:
		dev->net->stats.tx_bytes += skb->len;
	}
	dev->net->stats.tx_packets++;

	spin_lock(&dev->req_lock);
	list_add(&req->list, &dev->tx_reqs);
	spin_unlock(&dev->req_lock);
	dev_kfree_skb_any(skb);

	atomic_dec(&dev->tx_qlen);
	if (netif_carrier_ok(dev->net))
		netif_wake_queue(dev->net);
}

static inline int is_promisc(u16 cdc_filter)
{
	return cdc_filter & USB_CDC_PACKET_TYPE_PROMISCUOUS;
}

static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
					struct net_device *net)
{
	struct eth_dev		*dev = netdev_priv(net);
	int			length = 0;
	int			retval;
	struct usb_request	*req = NULL;
	unsigned long		flags;
	struct usb_ep		*in;
	u16			cdc_filter;

	spin_lock_irqsave(&dev->lock, flags);
	if (dev->port_usb) {
		in = dev->port_usb->in_ep;
		cdc_filter = dev->port_usb->cdc_filter;
	} else {
		in = NULL;
		cdc_filter = 0;
	}
	spin_unlock_irqrestore(&dev->lock, flags);

	if (skb && !in) {
		dev_kfree_skb_any(skb);
		return NETDEV_TX_OK;
	}

	/* apply outgoing CDC or RNDIS filters */
	if (skb && !is_promisc(cdc_filter)) {
		u8		*dest = skb->data;

		if (is_multicast_ether_addr(dest)) {
			u16	type;

			/* ignores USB_CDC_PACKET_TYPE_MULTICAST and host
			 * SET_ETHERNET_MULTICAST_FILTERS requests
			 */
			if (is_broadcast_ether_addr(dest))
				type = USB_CDC_PACKET_TYPE_BROADCAST;
			else
				type = USB_CDC_PACKET_TYPE_ALL_MULTICAST;
			if (!(cdc_filter & type)) {
				dev_kfree_skb_any(skb);
				return NETDEV_TX_OK;
			}
		}
		/* ignores USB_CDC_PACKET_TYPE_DIRECTED */
	}

	spin_lock_irqsave(&dev->req_lock, flags);
	/*
	 * this freelist can be empty if an interrupt triggered disconnect()
	 * and reconfigured the gadget (shutting down this queue) after the
	 * network stack decided to xmit but before we got the spinlock.
	 */
	if (list_empty(&dev->tx_reqs)) {
		spin_unlock_irqrestore(&dev->req_lock, flags);
		return NETDEV_TX_BUSY;
	}

	req = container_of(dev->tx_reqs.next, struct usb_request, list);
	list_del(&req->list);

	/* temporarily stop TX queue when the freelist empties */
	if (list_empty(&dev->tx_reqs))
		netif_stop_queue(net);
	spin_unlock_irqrestore(&dev->req_lock, flags);

	/* no buffer copies needed, unless the network stack did it
	 * or the hardware can't use skb buffers.
	 * or there's not enough space for extra headers we need
	 */
	if (dev->wrap) {
		unsigned long	flags;

		spin_lock_irqsave(&dev->lock, flags);
		if (dev->port_usb)
			skb = dev->wrap(dev->port_usb, skb);
		spin_unlock_irqrestore(&dev->lock, flags);
		if (!skb) {
			/* Multi frame CDC protocols may store the frame for
			 * later which is not a dropped frame.
			 */
			if (dev->port_usb->supports_multi_frame)
				goto multiframe;
			goto drop;
		}
	}

	length = skb->len;
	req->buf = skb->data;
	req->context = skb;
	req->complete = tx_complete;

	/* NCM requires no zlp if transfer is dwNtbInMaxSize */
	if (dev->port_usb->is_fixed &&
	    length == dev->port_usb->fixed_in_len &&
	    (length % in->maxpacket) == 0)
		req->zero = 0;
	else
		req->zero = 1;

	/* use zlp framing on tx for strict CDC-Ether conformance,
	 * though any robust network rx path ignores extra padding.
	 * and some hardware doesn't like to write zlps.
	 */
	if (req->zero && !dev->zlp && (length % in->maxpacket) == 0)
		length++;

	req->length = length;

	/* throttle high/super speed IRQ rate back slightly */
	if (gadget_is_dualspeed(dev->gadget))
		req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH ||
				     dev->gadget->speed == USB_SPEED_SUPER)
			? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0)
			: 0;

	retval = usb_ep_queue(in, req, GFP_ATOMIC);
	switch (retval) {
	default:
		DBG(dev, "tx queue err %d\n", retval);
		break;
	case 0:
		net->trans_start = jiffies;
		atomic_inc(&dev->tx_qlen);
	}

	if (retval) {
		dev_kfree_skb_any(skb);
drop:
		dev->net->stats.tx_dropped++;
multiframe:
		spin_lock_irqsave(&dev->req_lock, flags);
		if (list_empty(&dev->tx_reqs))
			netif_start_queue(net);
		list_add(&req->list, &dev->tx_reqs);
		spin_unlock_irqrestore(&dev->req_lock, flags);
	}
	return NETDEV_TX_OK;
}

/*-------------------------------------------------------------------------*/

static void eth_start(struct eth_dev *dev, gfp_t gfp_flags)
{
	DBG(dev, "%s\n", __func__);

	/* fill the rx queue */
	rx_fill(dev, gfp_flags);

	/* and open the tx floodgates */
	atomic_set(&dev->tx_qlen, 0);
	netif_wake_queue(dev->net);
}

static int eth_open(struct net_device *net)
{
	struct eth_dev	*dev = netdev_priv(net);
	struct gether	*link;

	DBG(dev, "%s\n", __func__);
	if (netif_carrier_ok(dev->net))
		eth_start(dev, GFP_KERNEL);

	spin_lock_irq(&dev->lock);
	link = dev->port_usb;
	if (link && link->open)
		link->open(link);
	spin_unlock_irq(&dev->lock);

	return 0;
}

static int eth_stop(struct net_device *net)
{
	struct eth_dev	*dev = netdev_priv(net);
	unsigned long	flags;

	VDBG(dev, "%s\n", __func__);
	netif_stop_queue(net);

	DBG(dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld\n",
		dev->net->stats.rx_packets, dev->net->stats.tx_packets,
		dev->net->stats.rx_errors, dev->net->stats.tx_errors
		);

	/* ensure there are no more active requests */
	spin_lock_irqsave(&dev->lock, flags);
	if (dev->port_usb) {
		struct gether	*link = dev->port_usb;
		const struct usb_endpoint_descriptor *in;
		const struct usb_endpoint_descriptor *out;

		if (link->close)
			link->close(link);

		/* NOTE:  we have no abort-queue primitive we could use
		 * to cancel all pending I/O.  Instead, we disable then
		 * reenable the endpoints ... this idiom may leave toggle
		 * wrong, but that's a self-correcting error.
		 *
		 * REVISIT:  we *COULD* just let the transfers complete at
		 * their own pace; the network stack can handle old packets.
		 * For the moment we leave this here, since it works.
		 */
		in = link->in_ep->desc;
		out = link->out_ep->desc;
		usb_ep_disable(link->in_ep);
		usb_ep_disable(link->out_ep);
		if (netif_carrier_ok(net)) {
			DBG(dev, "host still using in/out endpoints\n");
			link->in_ep->desc = in;
			link->out_ep->desc = out;
			usb_ep_enable(link->in_ep);
			usb_ep_enable(link->out_ep);
		}
	}
	spin_unlock_irqrestore(&dev->lock, flags);

	return 0;
}

/*-------------------------------------------------------------------------*/

static int get_ether_addr(const char *str, u8 *dev_addr)
{
	if (str) {
		unsigned	i;

		for (i = 0; i < 6; i++) {
			unsigned char num;

			if ((*str == '.') || (*str == ':'))
				str++;
			num = hex_to_bin(*str++) << 4;
			num |= hex_to_bin(*str++);
			dev_addr [i] = num;
		}
		if (is_valid_ether_addr(dev_addr))
			return 0;
	}
	eth_random_addr(dev_addr);
	return 1;
}

static int get_ether_addr_str(u8 dev_addr[ETH_ALEN], char *str, int len)
{
	if (len < 18)
		return -EINVAL;

	snprintf(str, len, "%02x:%02x:%02x:%02x:%02x:%02x",
		 dev_addr[0], dev_addr[1], dev_addr[2],
		 dev_addr[3], dev_addr[4], dev_addr[5]);
	return 18;
}

static const struct net_device_ops eth_netdev_ops = {
	.ndo_open		= eth_open,
	.ndo_stop		= eth_stop,
	.ndo_start_xmit		= eth_start_xmit,
	.ndo_change_mtu		= ueth_change_mtu,
	.ndo_set_mac_address 	= eth_mac_addr,
	.ndo_validate_addr	= eth_validate_addr,
};

static struct device_type gadget_type = {
	.name	= "gadget",
};

/**
 * gether_setup_name - initialize one ethernet-over-usb link
 * @g: gadget to associated with these links
 * @ethaddr: NULL, or a buffer in which the ethernet address of the
 *	host side of the link is recorded
 * @netname: name for network device (for example, "usb")
 * Context: may sleep
 *
 * This sets up the single network link that may be exported by a
 * gadget driver using this framework.  The link layer addresses are
 * set up using module parameters.
 *
 * Returns an eth_dev pointer on success, or an ERR_PTR on failure.
 */
struct eth_dev *gether_setup_name(struct usb_gadget *g,
		const char *dev_addr, const char *host_addr,
		u8 ethaddr[ETH_ALEN], unsigned qmult, const char *netname)
{
	struct eth_dev		*dev;
	struct net_device	*net;
	int			status;

	net = alloc_etherdev(sizeof *dev);
	if (!net)
		return ERR_PTR(-ENOMEM);

	dev = netdev_priv(net);
	spin_lock_init(&dev->lock);
	spin_lock_init(&dev->req_lock);
	INIT_WORK(&dev->work, eth_work);
	INIT_LIST_HEAD(&dev->tx_reqs);
	INIT_LIST_HEAD(&dev->rx_reqs);

	skb_queue_head_init(&dev->rx_frames);

	/* network device setup */
	dev->net = net;
	dev->qmult = qmult;
	snprintf(net->name, sizeof(net->name), "%s%%d", netname);

	if (get_ether_addr(dev_addr, net->dev_addr))
		dev_warn(&g->dev,
			"using random %s ethernet address\n", "self");
	if (get_ether_addr(host_addr, dev->host_mac))
		dev_warn(&g->dev,
			"using random %s ethernet address\n", "host");

	if (ethaddr)
		memcpy(ethaddr, dev->host_mac, ETH_ALEN);

	net->netdev_ops = &eth_netdev_ops;

	net->ethtool_ops = &ops;

	dev->gadget = g;
	SET_NETDEV_DEV(net, &g->dev);
	SET_NETDEV_DEVTYPE(net, &gadget_type);

	status = register_netdev(net);
	if (status < 0) {
		dev_dbg(&g->dev, "register_netdev failed, %d\n", status);
		free_netdev(net);
		dev = ERR_PTR(status);
	} else {
		INFO(dev, "MAC %pM\n", net->dev_addr);
		INFO(dev, "HOST MAC %pM\n", dev->host_mac);

		/*
		 * two kinds of host-initiated state changes:
		 *  - iff DATA transfer is active, carrier is "on"
		 *  - tx queueing enabled if open *and* carrier is "on"
		 */
		netif_carrier_off(net);
	}

	return dev;
}
EXPORT_SYMBOL_GPL(gether_setup_name);

struct net_device *gether_setup_name_default(const char *netname)
{
	struct net_device	*net;
	struct eth_dev		*dev;

	net = alloc_etherdev(sizeof(*dev));
	if (!net)
		return ERR_PTR(-ENOMEM);

	dev = netdev_priv(net);
	spin_lock_init(&dev->lock);
	spin_lock_init(&dev->req_lock);
	INIT_WORK(&dev->work, eth_work);
	INIT_LIST_HEAD(&dev->tx_reqs);
	INIT_LIST_HEAD(&dev->rx_reqs);

	skb_queue_head_init(&dev->rx_frames);

	/* network device setup */
	dev->net = net;
	dev->qmult = QMULT_DEFAULT;
	snprintf(net->name, sizeof(net->name), "%s%%d", netname);

	eth_random_addr(dev->dev_mac);
	pr_warn("using random %s ethernet address\n", "self");
	eth_random_addr(dev->host_mac);
	pr_warn("using random %s ethernet address\n", "host");

	net->netdev_ops = &eth_netdev_ops;

	net->ethtool_ops = &ops;
	SET_NETDEV_DEVTYPE(net, &gadget_type);

	return net;
}
EXPORT_SYMBOL_GPL(gether_setup_name_default);

int gether_register_netdev(struct net_device *net)
{
	struct eth_dev *dev;
	struct usb_gadget *g;
	struct sockaddr sa;
	int status;

	if (!net->dev.parent)
		return -EINVAL;
	dev = netdev_priv(net);
	g = dev->gadget;
	status = register_netdev(net);
	if (status < 0) {
		dev_dbg(&g->dev, "register_netdev failed, %d\n", status);
		return status;
	} else {
		INFO(dev, "HOST MAC %pM\n", dev->host_mac);

		/* two kinds of host-initiated state changes:
		 *  - iff DATA transfer is active, carrier is "on"
		 *  - tx queueing enabled if open *and* carrier is "on"
		 */
		netif_carrier_off(net);
	}
	sa.sa_family = net->type;
	memcpy(sa.sa_data, dev->dev_mac, ETH_ALEN);
	rtnl_lock();
	status = dev_set_mac_address(net, &sa);
	rtnl_unlock();
	if (status)
		pr_warn("cannot set self ethernet address: %d\n", status);
	else
		INFO(dev, "MAC %pM\n", dev->dev_mac);

	return status;
}
EXPORT_SYMBOL_GPL(gether_register_netdev);

void gether_set_gadget(struct net_device *net, struct usb_gadget *g)
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	dev->gadget = g;
	SET_NETDEV_DEV(net, &g->dev);
}
EXPORT_SYMBOL_GPL(gether_set_gadget);

int gether_set_dev_addr(struct net_device *net, const char *dev_addr)
{
	struct eth_dev *dev;
	u8 new_addr[ETH_ALEN];

	dev = netdev_priv(net);
	if (get_ether_addr(dev_addr, new_addr))
		return -EINVAL;
	memcpy(dev->dev_mac, new_addr, ETH_ALEN);
	return 0;
}
EXPORT_SYMBOL_GPL(gether_set_dev_addr);

int gether_get_dev_addr(struct net_device *net, char *dev_addr, int len)
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	return get_ether_addr_str(dev->dev_mac, dev_addr, len);
}
EXPORT_SYMBOL_GPL(gether_get_dev_addr);

int gether_set_host_addr(struct net_device *net, const char *host_addr)
{
	struct eth_dev *dev;
	u8 new_addr[ETH_ALEN];

	dev = netdev_priv(net);
	if (get_ether_addr(host_addr, new_addr))
		return -EINVAL;
	memcpy(dev->host_mac, new_addr, ETH_ALEN);
	return 0;
}
EXPORT_SYMBOL_GPL(gether_set_host_addr);

int gether_get_host_addr(struct net_device *net, char *host_addr, int len)
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	return get_ether_addr_str(dev->host_mac, host_addr, len);
}
EXPORT_SYMBOL_GPL(gether_get_host_addr);

int gether_get_host_addr_cdc(struct net_device *net, char *host_addr, int len)
{
	struct eth_dev *dev;

	if (len < 13)
		return -EINVAL;

	dev = netdev_priv(net);
	snprintf(host_addr, len, "%pm", dev->host_mac);

	return strlen(host_addr);
}
EXPORT_SYMBOL_GPL(gether_get_host_addr_cdc);

void gether_get_host_addr_u8(struct net_device *net, u8 host_mac[ETH_ALEN])
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	memcpy(host_mac, dev->host_mac, ETH_ALEN);
}
EXPORT_SYMBOL_GPL(gether_get_host_addr_u8);

void gether_set_qmult(struct net_device *net, unsigned qmult)
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	dev->qmult = qmult;
}
EXPORT_SYMBOL_GPL(gether_set_qmult);

unsigned gether_get_qmult(struct net_device *net)
{
	struct eth_dev *dev;

	dev = netdev_priv(net);
	return dev->qmult;
}
EXPORT_SYMBOL_GPL(gether_get_qmult);

int gether_get_ifname(struct net_device *net, char *name, int len)
{
	rtnl_lock();
	strlcpy(name, netdev_name(net), len);
	rtnl_unlock();
	return strlen(name);
}
EXPORT_SYMBOL_GPL(gether_get_ifname);

/**
 * gether_cleanup - remove Ethernet-over-USB device
 * Context: may sleep
 *
 * This is called to free all resources allocated by @gether_setup().
 */
void gether_cleanup(struct eth_dev *dev)
{
	if (!dev)
		return;

	unregister_netdev(dev->net);
	flush_work(&dev->work);
	free_netdev(dev->net);
}
EXPORT_SYMBOL_GPL(gether_cleanup);

/**
 * gether_connect - notify network layer that USB link is active
 * @link: the USB link, set up with endpoints, descriptors matching
 *	current device speed, and any framing wrapper(s) set up.
 * Context: irqs blocked
 *
 * This is called to activate endpoints and let the network layer know
 * the connection is active ("carrier detect").  It may cause the I/O
 * queues to open and start letting network packets flow, but will in
 * any case activate the endpoints so that they respond properly to the
 * USB host.
 *
 * Verify net_device pointer returned using IS_ERR().  If it doesn't
 * indicate some error code (negative errno), ep->driver_data values
 * have been overwritten.
 */
struct net_device *gether_connect(struct gether *link)
{
	struct eth_dev		*dev = link->ioport;
	int			result = 0;

	if (!dev)
		return ERR_PTR(-EINVAL);

	link->in_ep->driver_data = dev;
	result = usb_ep_enable(link->in_ep);
	if (result != 0) {
		DBG(dev, "enable %s --> %d\n",
			link->in_ep->name, result);
		goto fail0;
	}

	link->out_ep->driver_data = dev;
	result = usb_ep_enable(link->out_ep);
	if (result != 0) {
		DBG(dev, "enable %s --> %d\n",
			link->out_ep->name, result);
		goto fail1;
	}

	if (result == 0)
		result = alloc_requests(dev, link, qlen(dev->gadget,
					dev->qmult));

	if (result == 0) {
		dev->zlp = link->is_zlp_ok;
		DBG(dev, "qlen %d\n", qlen(dev->gadget, dev->qmult));

		dev->header_len = link->header_len;
		dev->unwrap = link->unwrap;
		dev->wrap = link->wrap;

		spin_lock(&dev->lock);
		dev->port_usb = link;
		if (netif_running(dev->net)) {
			if (link->open)
				link->open(link);
		} else {
			if (link->close)
				link->close(link);
		}
		spin_unlock(&dev->lock);

		netif_carrier_on(dev->net);
		if (netif_running(dev->net))
			eth_start(dev, GFP_ATOMIC);

	/* on error, disable any endpoints  */
	} else {
		(void) usb_ep_disable(link->out_ep);
fail1:
		(void) usb_ep_disable(link->in_ep);
	}
fail0:
	/* caller is responsible for cleanup on error */
	if (result < 0)
		return ERR_PTR(result);
	return dev->net;
}
EXPORT_SYMBOL_GPL(gether_connect);

/**
 * gether_disconnect - notify network layer that USB link is inactive
 * @link: the USB link, on which gether_connect() was called
 * Context: irqs blocked
 *
 * This is called to deactivate endpoints and let the network layer know
 * the connection went inactive ("no carrier").
 *
 * On return, the state is as if gether_connect() had never been called.
 * The endpoints are inactive, and accordingly without active USB I/O.
 * Pointers to endpoint descriptors and endpoint private data are nulled.
 */
void gether_disconnect(struct gether *link)
{
	struct eth_dev		*dev = link->ioport;
	struct usb_request	*req;

	WARN_ON(!dev);
	if (!dev)
		return;

	DBG(dev, "%s\n", __func__);

	netif_stop_queue(dev->net);
	netif_carrier_off(dev->net);

	/* disable endpoints, forcing (synchronous) completion
	 * of all pending i/o.  then free the request objects
	 * and forget about the endpoints.
	 */
	usb_ep_disable(link->in_ep);
	spin_lock(&dev->req_lock);
	while (!list_empty(&dev->tx_reqs)) {
		req = container_of(dev->tx_reqs.next,
					struct usb_request, list);
		list_del(&req->list);

		spin_unlock(&dev->req_lock);
		usb_ep_free_request(link->in_ep, req);
		spin_lock(&dev->req_lock);
	}
	spin_unlock(&dev->req_lock);
	link->in_ep->driver_data = NULL;
	link->in_ep->desc = NULL;

	usb_ep_disable(link->out_ep);
	spin_lock(&dev->req_lock);
	while (!list_empty(&dev->rx_reqs)) {
		req = container_of(dev->rx_reqs.next,
					struct usb_request, list);
		list_del(&req->list);

		spin_unlock(&dev->req_lock);
		usb_ep_free_request(link->out_ep, req);
		spin_lock(&dev->req_lock);
	}
	spin_unlock(&dev->req_lock);
	link->out_ep->driver_data = NULL;
	link->out_ep->desc = NULL;

	/* finish forgetting about this USB link episode */
	dev->header_len = 0;
	dev->unwrap = NULL;
	dev->wrap = NULL;

	spin_lock(&dev->lock);
	dev->port_usb = NULL;
	spin_unlock(&dev->lock);
}
EXPORT_SYMBOL_GPL(gether_disconnect);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");