aboutsummaryrefslogtreecommitdiffstats
blob: a244265c114348a9568045e72977bc34e46804d2 (plain) (blame)
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
1180
/*
 * Gadget Function Driver for Android USB accessories
 *
 * Copyright (C) 2011 Google, Inc.
 * Author: Mike Lockwood <lockwood@android.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

/* #define DEBUG */
/* #define VERBOSE_DEBUG */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <linux/freezer.h>

#include <linux/types.h>
#include <linux/file.h>
#include <linux/device.h>
#include <linux/miscdevice.h>

#include <linux/hid.h>
#include <linux/hiddev.h>
#include <linux/usb.h>
#include <linux/usb/ch9.h>
#include <linux/usb/f_accessory.h>

#define BULK_BUFFER_SIZE    16384
#define ACC_STRING_SIZE     256

#define PROTOCOL_VERSION    2

/* String IDs */
#define INTERFACE_STRING_INDEX	0

/* number of tx and rx requests to allocate */
#define TX_REQ_MAX 4
#define RX_REQ_MAX 2

struct acc_hid_dev {
	struct list_head	list;
	struct hid_device *hid;
	struct acc_dev *dev;
	/* accessory defined ID */
	int id;
	/* HID report descriptor */
	u8 *report_desc;
	/* length of HID report descriptor */
	int report_desc_len;
	/* number of bytes of report_desc we have received so far */
	int report_desc_offset;
};

struct acc_dev {
	struct usb_function function;
	struct usb_composite_dev *cdev;
	spinlock_t lock;

	struct usb_ep *ep_in;
	struct usb_ep *ep_out;

	/* set to 1 when we connect */
	int online:1;
	/* Set to 1 when we disconnect.
	 * Not cleared until our file is closed.
	 */
	int disconnected:1;

	/* strings sent by the host */
	char manufacturer[ACC_STRING_SIZE];
	char model[ACC_STRING_SIZE];
	char description[ACC_STRING_SIZE];
	char version[ACC_STRING_SIZE];
	char uri[ACC_STRING_SIZE];
	char serial[ACC_STRING_SIZE];

	/* for acc_complete_set_string */
	int string_index;

	/* set to 1 if we have a pending start request */
	int start_requested;

	int audio_mode;

	/* synchronize access to our device file */
	atomic_t open_excl;

	struct list_head tx_idle;

	wait_queue_head_t read_wq;
	wait_queue_head_t write_wq;
	struct usb_request *rx_req[RX_REQ_MAX];
	int rx_done;

	/* delayed work for handling ACCESSORY_START */
	struct delayed_work start_work;

	/* worker for registering and unregistering hid devices */
	struct work_struct hid_work;

	/* list of active HID devices */
	struct list_head	hid_list;

	/* list of new HID devices to register */
	struct list_head	new_hid_list;

	/* list of dead HID devices to unregister */
	struct list_head	dead_hid_list;
};

static struct usb_interface_descriptor acc_interface_desc = {
	.bLength                = USB_DT_INTERFACE_SIZE,
	.bDescriptorType        = USB_DT_INTERFACE,
	.bInterfaceNumber       = 0,
	.bNumEndpoints          = 2,
	.bInterfaceClass        = USB_CLASS_VENDOR_SPEC,
	.bInterfaceSubClass     = USB_SUBCLASS_VENDOR_SPEC,
	.bInterfaceProtocol     = 0,
};

static struct usb_endpoint_descriptor acc_highspeed_in_desc = {
	.bLength                = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType        = USB_DT_ENDPOINT,
	.bEndpointAddress       = USB_DIR_IN,
	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize         = __constant_cpu_to_le16(512),
};

static struct usb_endpoint_descriptor acc_highspeed_out_desc = {
	.bLength                = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType        = USB_DT_ENDPOINT,
	.bEndpointAddress       = USB_DIR_OUT,
	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize         = __constant_cpu_to_le16(512),
};

static struct usb_endpoint_descriptor acc_fullspeed_in_desc = {
	.bLength                = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType        = USB_DT_ENDPOINT,
	.bEndpointAddress       = USB_DIR_IN,
	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor acc_fullspeed_out_desc = {
	.bLength                = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType        = USB_DT_ENDPOINT,
	.bEndpointAddress       = USB_DIR_OUT,
	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *fs_acc_descs[] = {
	(struct usb_descriptor_header *) &acc_interface_desc,
	(struct usb_descriptor_header *) &acc_fullspeed_in_desc,
	(struct usb_descriptor_header *) &acc_fullspeed_out_desc,
	NULL,
};

static struct usb_descriptor_header *hs_acc_descs[] = {
	(struct usb_descriptor_header *) &acc_interface_desc,
	(struct usb_descriptor_header *) &acc_highspeed_in_desc,
	(struct usb_descriptor_header *) &acc_highspeed_out_desc,
	NULL,
};

static struct usb_string acc_string_defs[] = {
	[INTERFACE_STRING_INDEX].s	= "Android Accessory Interface",
	{  },	/* end of list */
};

static struct usb_gadget_strings acc_string_table = {
	.language		= 0x0409,	/* en-US */
	.strings		= acc_string_defs,
};

static struct usb_gadget_strings *acc_strings[] = {
	&acc_string_table,
	NULL,
};

/* temporary variable used between acc_open() and acc_gadget_bind() */
static struct acc_dev *_acc_dev;

static inline struct acc_dev *func_to_dev(struct usb_function *f)
{
	return container_of(f, struct acc_dev, function);
}

static struct usb_request *acc_request_new(struct usb_ep *ep, int buffer_size)
{
	struct usb_request *req = usb_ep_alloc_request(ep, GFP_KERNEL);
	if (!req)
		return NULL;

	/* now allocate buffers for the requests */
	req->buf = kmalloc(buffer_size, GFP_KERNEL);
	if (!req->buf) {
		usb_ep_free_request(ep, req);
		return NULL;
	}

	return req;
}

static void acc_request_free(struct usb_request *req, struct usb_ep *ep)
{
	if (req) {
		kfree(req->buf);
		usb_ep_free_request(ep, req);
	}
}

/* add a request to the tail of a list */
static void req_put(struct acc_dev *dev, struct list_head *head,
		struct usb_request *req)
{
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);
	list_add_tail(&req->list, head);
	spin_unlock_irqrestore(&dev->lock, flags);
}

/* remove a request from the head of a list */
static struct usb_request *req_get(struct acc_dev *dev, struct list_head *head)
{
	unsigned long flags;
	struct usb_request *req;

	spin_lock_irqsave(&dev->lock, flags);
	if (list_empty(head)) {
		req = 0;
	} else {
		req = list_first_entry(head, struct usb_request, list);
		list_del(&req->list);
	}
	spin_unlock_irqrestore(&dev->lock, flags);
	return req;
}

static void acc_set_disconnected(struct acc_dev *dev)
{
	dev->online = 0;
	dev->disconnected = 1;
}

static void acc_complete_in(struct usb_ep *ep, struct usb_request *req)
{
	struct acc_dev *dev = _acc_dev;

	if (req->status != 0)
		acc_set_disconnected(dev);

	req_put(dev, &dev->tx_idle, req);

	wake_up(&dev->write_wq);
}

static void acc_complete_out(struct usb_ep *ep, struct usb_request *req)
{
	struct acc_dev *dev = _acc_dev;

	dev->rx_done = 1;
	if (req->status != 0)
		acc_set_disconnected(dev);

	wake_up(&dev->read_wq);
}

static void acc_complete_set_string(struct usb_ep *ep, struct usb_request *req)
{
	struct acc_dev	*dev = ep->driver_data;
	char *string_dest = NULL;
	int length = req->actual;

	if (req->status != 0) {
		pr_err("acc_complete_set_string, err %d\n", req->status);
		return;
	}

	switch (dev->string_index) {
	case ACCESSORY_STRING_MANUFACTURER:
		string_dest = dev->manufacturer;
		break;
	case ACCESSORY_STRING_MODEL:
		string_dest = dev->model;
		break;
	case ACCESSORY_STRING_DESCRIPTION:
		string_dest = dev->description;
		break;
	case ACCESSORY_STRING_VERSION:
		string_dest = dev->version;
		break;
	case ACCESSORY_STRING_URI:
		string_dest = dev->uri;
		break;
	case ACCESSORY_STRING_SERIAL:
		string_dest = dev->serial;
		break;
	}
	if (string_dest) {
		unsigned long flags;

		if (length >= ACC_STRING_SIZE)
			length = ACC_STRING_SIZE - 1;

		spin_lock_irqsave(&dev->lock, flags);
		memcpy(string_dest, req->buf, length);
		/* ensure zero termination */
		string_dest[length] = 0;
		spin_unlock_irqrestore(&dev->lock, flags);
	} else {
		pr_err("unknown accessory string index %d\n",
			dev->string_index);
	}
}

static void acc_complete_set_hid_report_desc(struct usb_ep *ep,
		struct usb_request *req)
{
	struct acc_hid_dev *hid = req->context;
	struct acc_dev *dev = hid->dev;
	int length = req->actual;

	if (req->status != 0) {
		pr_err("acc_complete_set_hid_report_desc, err %d\n",
			req->status);
		return;
	}

	memcpy(hid->report_desc + hid->report_desc_offset, req->buf, length);
	hid->report_desc_offset += length;
	if (hid->report_desc_offset == hid->report_desc_len) {
		/* After we have received the entire report descriptor
		 * we schedule work to initialize the HID device
		 */
		schedule_work(&dev->hid_work);
	}
}

static void acc_complete_send_hid_event(struct usb_ep *ep,
		struct usb_request *req)
{
	struct acc_hid_dev *hid = req->context;
	int length = req->actual;

	if (req->status != 0) {
		pr_err("acc_complete_send_hid_event, err %d\n", req->status);
		return;
	}

	hid_report_raw_event(hid->hid, HID_INPUT_REPORT, req->buf, length, 1);
}

static int acc_hid_parse(struct hid_device *hid)
{
	struct acc_hid_dev *hdev = hid->driver_data;

	hid_parse_report(hid, hdev->report_desc, hdev->report_desc_len);
	return 0;
}

static int acc_hid_start(struct hid_device *hid)
{
	return 0;
}

static void acc_hid_stop(struct hid_device *hid)
{
}

static int acc_hid_open(struct hid_device *hid)
{
	return 0;
}

static void acc_hid_close(struct hid_device *hid)
{
}

static struct hid_ll_driver acc_hid_ll_driver = {
	.parse = acc_hid_parse,
	.start = acc_hid_start,
	.stop = acc_hid_stop,
	.open = acc_hid_open,
	.close = acc_hid_close,
};

static struct acc_hid_dev *acc_hid_new(struct acc_dev *dev,
		int id, int desc_len)
{
	struct acc_hid_dev *hdev;

	hdev = kzalloc(sizeof(*hdev), GFP_ATOMIC);
	if (!hdev)
		return NULL;
	hdev->report_desc = kzalloc(desc_len, GFP_ATOMIC);
	if (!hdev->report_desc) {
		kfree(hdev);
		return NULL;
	}
	hdev->dev = dev;
	hdev->id = id;
	hdev->report_desc_len = desc_len;

	return hdev;
}

static struct acc_hid_dev *acc_hid_get(struct list_head *list, int id)
{
	struct acc_hid_dev *hid;

	list_for_each_entry(hid, list, list) {
		if (hid->id == id)
			return hid;
	}
	return NULL;
}

static int acc_register_hid(struct acc_dev *dev, int id, int desc_length)
{
	struct acc_hid_dev *hid;
	unsigned long flags;

	/* report descriptor length must be > 0 */
	if (desc_length <= 0)
		return -EINVAL;

	spin_lock_irqsave(&dev->lock, flags);
	/* replace HID if one already exists with this ID */
	hid = acc_hid_get(&dev->hid_list, id);
	if (!hid)
		hid = acc_hid_get(&dev->new_hid_list, id);
	if (hid)
		list_move(&hid->list, &dev->dead_hid_list);

	hid = acc_hid_new(dev, id, desc_length);
	if (!hid) {
		spin_unlock_irqrestore(&dev->lock, flags);
		return -ENOMEM;
	}

	list_add(&hid->list, &dev->new_hid_list);
	spin_unlock_irqrestore(&dev->lock, flags);

	/* schedule work to register the HID device */
	schedule_work(&dev->hid_work);
	return 0;
}

static int acc_unregister_hid(struct acc_dev *dev, int id)
{
	struct acc_hid_dev *hid;
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);
	hid = acc_hid_get(&dev->hid_list, id);
	if (!hid)
		hid = acc_hid_get(&dev->new_hid_list, id);
	if (!hid) {
		spin_unlock_irqrestore(&dev->lock, flags);
		return -EINVAL;
	}

	list_move(&hid->list, &dev->dead_hid_list);
	spin_unlock_irqrestore(&dev->lock, flags);

	schedule_work(&dev->hid_work);
	return 0;
}

static int create_bulk_endpoints(struct acc_dev *dev,
				struct usb_endpoint_descriptor *in_desc,
				struct usb_endpoint_descriptor *out_desc)
{
	struct usb_composite_dev *cdev = dev->cdev;
	struct usb_request *req;
	struct usb_ep *ep;
	int i;

	DBG(cdev, "create_bulk_endpoints dev: %p\n", dev);

	ep = usb_ep_autoconfig(cdev->gadget, in_desc);
	if (!ep) {
		DBG(cdev, "usb_ep_autoconfig for ep_in failed\n");
		return -ENODEV;
	}
	DBG(cdev, "usb_ep_autoconfig for ep_in got %s\n", ep->name);
	ep->driver_data = dev;		/* claim the endpoint */
	dev->ep_in = ep;

	ep = usb_ep_autoconfig(cdev->gadget, out_desc);
	if (!ep) {
		DBG(cdev, "usb_ep_autoconfig for ep_out failed\n");
		return -ENODEV;
	}
	DBG(cdev, "usb_ep_autoconfig for ep_out got %s\n", ep->name);
	ep->driver_data = dev;		/* claim the endpoint */
	dev->ep_out = ep;

	ep = usb_ep_autoconfig(cdev->gadget, out_desc);
	if (!ep) {
		DBG(cdev, "usb_ep_autoconfig for ep_out failed\n");
		return -ENODEV;
	}
	DBG(cdev, "usb_ep_autoconfig for ep_out got %s\n", ep->name);
	ep->driver_data = dev;		/* claim the endpoint */
	dev->ep_out = ep;

	/* now allocate requests for our endpoints */
	for (i = 0; i < TX_REQ_MAX; i++) {
		req = acc_request_new(dev->ep_in, BULK_BUFFER_SIZE);
		if (!req)
			goto fail;
		req->complete = acc_complete_in;
		req_put(dev, &dev->tx_idle, req);
	}
	for (i = 0; i < RX_REQ_MAX; i++) {
		req = acc_request_new(dev->ep_out, BULK_BUFFER_SIZE);
		if (!req)
			goto fail;
		req->complete = acc_complete_out;
		dev->rx_req[i] = req;
	}

	return 0;

fail:
	pr_err("acc_bind() could not allocate requests\n");
	while ((req = req_get(dev, &dev->tx_idle)))
		acc_request_free(req, dev->ep_in);
	for (i = 0; i < RX_REQ_MAX; i++)
		acc_request_free(dev->rx_req[i], dev->ep_out);
	return -1;
}

static ssize_t acc_read(struct file *fp, char __user *buf,
	size_t count, loff_t *pos)
{
	struct acc_dev *dev = fp->private_data;
	struct usb_request *req;
	int r = count, xfer;
	int ret = 0;

	pr_debug("acc_read(%d)\n", count);

	if (dev->disconnected)
		return -ENODEV;

	if (count > BULK_BUFFER_SIZE)
		count = BULK_BUFFER_SIZE;

	/* we will block until we're online */
	pr_debug("acc_read: waiting for online\n");
	ret = wait_event_interruptible(dev->read_wq, dev->online);
	if (ret < 0) {
		r = ret;
		goto done;
	}

requeue_req:
	/* queue a request */
	req = dev->rx_req[0];
	req->length = count;
	dev->rx_done = 0;
	ret = usb_ep_queue(dev->ep_out, req, GFP_KERNEL);
	if (ret < 0) {
		r = -EIO;
		goto done;
	} else {
		pr_debug("rx %p queue\n", req);
	}

	/* wait for a request to complete */
	ret = wait_event_interruptible(dev->read_wq, dev->rx_done);
	if (ret < 0) {
		r = ret;
		usb_ep_dequeue(dev->ep_out, req);
		goto done;
	}
	if (dev->online) {
		/* If we got a 0-len packet, throw it back and try again. */
		if (req->actual == 0)
			goto requeue_req;

		pr_debug("rx %p %d\n", req, req->actual);
		xfer = (req->actual < count) ? req->actual : count;
		r = xfer;
		if (copy_to_user(buf, req->buf, xfer))
			r = -EFAULT;
	} else
		r = -EIO;

done:
	pr_debug("acc_read returning %d\n", r);
	return r;
}

static ssize_t acc_write(struct file *fp, const char __user *buf,
	size_t count, loff_t *pos)
{
	struct acc_dev *dev = fp->private_data;
	struct usb_request *req = 0;
	int r = count, xfer;
	int ret;

	pr_debug("acc_write(%d)\n", count);

	if (!dev->online || dev->disconnected)
		return -ENODEV;

	while (count > 0) {
		if (!dev->online) {
			pr_debug("acc_write dev->error\n");
			r = -EIO;
			break;
		}

		/* get an idle tx request to use */
		req = 0;
		ret = wait_event_interruptible(dev->write_wq,
			((req = req_get(dev, &dev->tx_idle)) || !dev->online));
		if (!req) {
			r = ret;
			break;
		}

		if (count > BULK_BUFFER_SIZE)
			xfer = BULK_BUFFER_SIZE;
		else
			xfer = count;
		if (copy_from_user(req->buf, buf, xfer)) {
			r = -EFAULT;
			break;
		}

		req->length = xfer;
		ret = usb_ep_queue(dev->ep_in, req, GFP_KERNEL);
		if (ret < 0) {
			pr_debug("acc_write: xfer error %d\n", ret);
			r = -EIO;
			break;
		}

		buf += xfer;
		count -= xfer;

		/* zero this so we don't try to free it on error exit */
		req = 0;
	}

	if (req)
		req_put(dev, &dev->tx_idle, req);

	pr_debug("acc_write returning %d\n", r);
	return r;
}

static long acc_ioctl(struct file *fp, unsigned code, unsigned long value)
{
	struct acc_dev *dev = fp->private_data;
	char *src = NULL;
	int ret;

	switch (code) {
	case ACCESSORY_GET_STRING_MANUFACTURER:
		src = dev->manufacturer;
		break;
	case ACCESSORY_GET_STRING_MODEL:
		src = dev->model;
		break;
	case ACCESSORY_GET_STRING_DESCRIPTION:
		src = dev->description;
		break;
	case ACCESSORY_GET_STRING_VERSION:
		src = dev->version;
		break;
	case ACCESSORY_GET_STRING_URI:
		src = dev->uri;
		break;
	case ACCESSORY_GET_STRING_SERIAL:
		src = dev->serial;
		break;
	case ACCESSORY_IS_START_REQUESTED:
		return dev->start_requested;
	case ACCESSORY_GET_AUDIO_MODE:
		return dev->audio_mode;
	}
	if (!src)
		return -EINVAL;

	ret = strlen(src) + 1;
	if (copy_to_user((void __user *)value, src, ret))
		ret = -EFAULT;
	return ret;
}

static int acc_open(struct inode *ip, struct file *fp)
{
	printk(KERN_INFO "acc_open\n");
	if (atomic_xchg(&_acc_dev->open_excl, 1))
		return -EBUSY;

	_acc_dev->disconnected = 0;
	fp->private_data = _acc_dev;
	return 0;
}

static int acc_release(struct inode *ip, struct file *fp)
{
	printk(KERN_INFO "acc_release\n");

	WARN_ON(!atomic_xchg(&_acc_dev->open_excl, 0));
	_acc_dev->disconnected = 0;
	return 0;
}

/* file operations for /dev/usb_accessory */
static const struct file_operations acc_fops = {
	.owner = THIS_MODULE,
	.read = acc_read,
	.write = acc_write,
	.unlocked_ioctl = acc_ioctl,
	.open = acc_open,
	.release = acc_release,
};

static int acc_hid_probe(struct hid_device *hdev,
		const struct hid_device_id *id)
{
	int ret;

	ret = hid_parse(hdev);
	if (ret)
		return ret;
	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
}

static struct miscdevice acc_device = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "usb_accessory",
	.fops = &acc_fops,
};

static const struct hid_device_id acc_hid_table[] = {
	{ HID_USB_DEVICE(HID_ANY_ID, HID_ANY_ID) },
	{ }
};

static struct hid_driver acc_hid_driver = {
	.name = "USB accessory",
	.id_table = acc_hid_table,
	.probe = acc_hid_probe,
};

static int acc_ctrlrequest(struct usb_composite_dev *cdev,
				const struct usb_ctrlrequest *ctrl)
{
	struct acc_dev	*dev = _acc_dev;
	int	value = -EOPNOTSUPP;
	struct acc_hid_dev *hid;
	int offset;
	u8 b_requestType = ctrl->bRequestType;
	u8 b_request = ctrl->bRequest;
	u16	w_index = le16_to_cpu(ctrl->wIndex);
	u16	w_value = le16_to_cpu(ctrl->wValue);
	u16	w_length = le16_to_cpu(ctrl->wLength);
	unsigned long flags;

/*
	printk(KERN_INFO "acc_ctrlrequest "
			"%02x.%02x v%04x i%04x l%u\n",
			b_requestType, b_request,
			w_value, w_index, w_length);
*/

	if (b_requestType == (USB_DIR_OUT | USB_TYPE_VENDOR)) {
		if (b_request == ACCESSORY_START) {
			dev->start_requested = 1;
			schedule_delayed_work(
				&dev->start_work, msecs_to_jiffies(10));
			value = 0;
		} else if (b_request == ACCESSORY_SEND_STRING) {
			dev->string_index = w_index;
			cdev->gadget->ep0->driver_data = dev;
			cdev->req->complete = acc_complete_set_string;
			value = w_length;
		} else if (b_request == ACCESSORY_SET_AUDIO_MODE &&
				w_index == 0 && w_length == 0) {
			dev->audio_mode = w_value;
			value = 0;
		} else if (b_request == ACCESSORY_REGISTER_HID) {
			value = acc_register_hid(dev, w_value, w_index);
		} else if (b_request == ACCESSORY_UNREGISTER_HID) {
			value = acc_unregister_hid(dev, w_value);
		} else if (b_request == ACCESSORY_SET_HID_REPORT_DESC) {
			spin_lock_irqsave(&dev->lock, flags);
			hid = acc_hid_get(&dev->new_hid_list, w_value);
			spin_unlock_irqrestore(&dev->lock, flags);
			if (!hid) {
				value = -EINVAL;
				goto err;
			}
			offset = w_index;
			if (offset != hid->report_desc_offset
				|| offset + w_length > hid->report_desc_len) {
				value = -EINVAL;
				goto err;
			}
			cdev->req->context = hid;
			cdev->req->complete = acc_complete_set_hid_report_desc;
			value = w_length;
		} else if (b_request == ACCESSORY_SEND_HID_EVENT) {
			spin_lock_irqsave(&dev->lock, flags);
			hid = acc_hid_get(&dev->hid_list, w_value);
			spin_unlock_irqrestore(&dev->lock, flags);
			if (!hid) {
				value = -EINVAL;
				goto err;
			}
			cdev->req->context = hid;
			cdev->req->complete = acc_complete_send_hid_event;
			value = w_length;
		}
	} else if (b_requestType == (USB_DIR_IN | USB_TYPE_VENDOR)) {
		if (b_request == ACCESSORY_GET_PROTOCOL) {
			*((u16 *)cdev->req->buf) = PROTOCOL_VERSION;
			value = sizeof(u16);

			/* clear any string left over from a previous session */
			memset(dev->manufacturer, 0, sizeof(dev->manufacturer));
			memset(dev->model, 0, sizeof(dev->model));
			memset(dev->description, 0, sizeof(dev->description));
			memset(dev->version, 0, sizeof(dev->version));
			memset(dev->uri, 0, sizeof(dev->uri));
			memset(dev->serial, 0, sizeof(dev->serial));
			dev->start_requested = 0;
			dev->audio_mode = 0;
		}
	}

	if (value >= 0) {
		cdev->req->zero = 0;
		cdev->req->length = value;
		value = usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
		if (value < 0)
			ERROR(cdev, "%s setup response queue error\n",
				__func__);
	}

err:
	if (value == -EOPNOTSUPP)
		VDBG(cdev,
			"unknown class-specific control req "
			"%02x.%02x v%04x i%04x l%u\n",
			ctrl->bRequestType, ctrl->bRequest,
			w_value, w_index, w_length);
	return value;
}

static int
acc_function_bind(struct usb_configuration *c, struct usb_function *f)
{
	struct usb_composite_dev *cdev = c->cdev;
	struct acc_dev	*dev = func_to_dev(f);
	int			id;
	int			ret;

	DBG(cdev, "acc_function_bind dev: %p\n", dev);

	ret = hid_register_driver(&acc_hid_driver);
	if (ret)
		return ret;

	dev->start_requested = 0;

	/* allocate interface ID(s) */
	id = usb_interface_id(c, f);
	if (id < 0)
		return id;
	acc_interface_desc.bInterfaceNumber = id;

	/* allocate endpoints */
	ret = create_bulk_endpoints(dev, &acc_fullspeed_in_desc,
			&acc_fullspeed_out_desc);
	if (ret)
		return ret;

	/* support high speed hardware */
	if (gadget_is_dualspeed(c->cdev->gadget)) {
		acc_highspeed_in_desc.bEndpointAddress =
			acc_fullspeed_in_desc.bEndpointAddress;
		acc_highspeed_out_desc.bEndpointAddress =
			acc_fullspeed_out_desc.bEndpointAddress;
	}

	DBG(cdev, "%s speed %s: IN/%s, OUT/%s\n",
			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
			f->name, dev->ep_in->name, dev->ep_out->name);
	return 0;
}

static void
kill_all_hid_devices(struct acc_dev *dev)
{
	struct acc_hid_dev *hid;
	struct list_head *entry, *temp;
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);
	list_for_each_safe(entry, temp, &dev->hid_list) {
		hid = list_entry(entry, struct acc_hid_dev, list);
		list_del(&hid->list);
		list_add(&hid->list, &dev->dead_hid_list);
	}
	list_for_each_safe(entry, temp, &dev->new_hid_list) {
		hid = list_entry(entry, struct acc_hid_dev, list);
		list_del(&hid->list);
		list_add(&hid->list, &dev->dead_hid_list);
	}
	spin_unlock_irqrestore(&dev->lock, flags);

	schedule_work(&dev->hid_work);
}

static void
acc_hid_unbind(struct acc_dev *dev)
{
	hid_unregister_driver(&acc_hid_driver);
	kill_all_hid_devices(dev);
}

static void
acc_function_unbind(struct usb_configuration *c, struct usb_function *f)
{
	struct acc_dev	*dev = func_to_dev(f);
	struct usb_request *req;
	int i;

	while ((req = req_get(dev, &dev->tx_idle)))
		acc_request_free(req, dev->ep_in);
	for (i = 0; i < RX_REQ_MAX; i++)
		acc_request_free(dev->rx_req[i], dev->ep_out);

	acc_hid_unbind(dev);
}

static void acc_start_work(struct work_struct *data)
{
	char *envp[2] = { "ACCESSORY=START", NULL };
	kobject_uevent_env(&acc_device.this_device->kobj, KOBJ_CHANGE, envp);
}

static int acc_hid_init(struct acc_hid_dev *hdev)
{
	struct hid_device *hid;
	int ret;

	hid = hid_allocate_device();
	if (IS_ERR(hid))
		return PTR_ERR(hid);

	hid->ll_driver = &acc_hid_ll_driver;
	hid->dev.parent = acc_device.this_device;

	hid->bus = BUS_USB;
	hid->vendor = HID_ANY_ID;
	hid->product = HID_ANY_ID;
	hid->driver_data = hdev;
	ret = hid_add_device(hid);
	if (ret) {
		pr_err("can't add hid device: %d\n", ret);
		hid_destroy_device(hid);
		return ret;
	}

	hdev->hid = hid;
	return 0;
}

static void acc_hid_delete(struct acc_hid_dev *hid)
{
	kfree(hid->report_desc);
	kfree(hid);
}

static void acc_hid_work(struct work_struct *data)
{
	struct acc_dev *dev = _acc_dev;
	struct list_head	*entry, *temp;
	struct acc_hid_dev *hid;
	struct list_head	new_list, dead_list;
	unsigned long flags;

	INIT_LIST_HEAD(&new_list);

	spin_lock_irqsave(&dev->lock, flags);

	/* copy hids that are ready for initialization to new_list */
	list_for_each_safe(entry, temp, &dev->new_hid_list) {
		hid = list_entry(entry, struct acc_hid_dev, list);
		if (hid->report_desc_offset == hid->report_desc_len)
			list_move(&hid->list, &new_list);
	}

	if (list_empty(&dev->dead_hid_list)) {
		INIT_LIST_HEAD(&dead_list);
	} else {
		/* move all of dev->dead_hid_list to dead_list */
		dead_list.prev = dev->dead_hid_list.prev;
		dead_list.next = dev->dead_hid_list.next;
		dead_list.next->prev = &dead_list;
		dead_list.prev->next = &dead_list;
		INIT_LIST_HEAD(&dev->dead_hid_list);
	}

	spin_unlock_irqrestore(&dev->lock, flags);

	/* register new HID devices */
	list_for_each_safe(entry, temp, &new_list) {
		hid = list_entry(entry, struct acc_hid_dev, list);
		if (acc_hid_init(hid)) {
			pr_err("can't add HID device %p\n", hid);
			acc_hid_delete(hid);
		} else {
			spin_lock_irqsave(&dev->lock, flags);
			list_move(&hid->list, &dev->hid_list);
			spin_unlock_irqrestore(&dev->lock, flags);
		}
	}

	/* remove dead HID devices */
	list_for_each_safe(entry, temp, &dead_list) {
		hid = list_entry(entry, struct acc_hid_dev, list);
		list_del(&hid->list);
		if (hid->hid)
			hid_destroy_device(hid->hid);
		acc_hid_delete(hid);
	}
}

static int acc_function_set_alt(struct usb_function *f,
		unsigned intf, unsigned alt)
{
	struct acc_dev	*dev = func_to_dev(f);
	struct usb_composite_dev *cdev = f->config->cdev;
	int ret;

	DBG(cdev, "acc_function_set_alt intf: %d alt: %d\n", intf, alt);

	ret = config_ep_by_speed(cdev->gadget, f, dev->ep_in);
	if (ret)
		return ret;

	ret = usb_ep_enable(dev->ep_in);
	if (ret)
		return ret;

	ret = config_ep_by_speed(cdev->gadget, f, dev->ep_out);
	if (ret)
		return ret;

	ret = usb_ep_enable(dev->ep_out);
	if (ret) {
		usb_ep_disable(dev->ep_in);
		return ret;
	}

	dev->online = 1;

	/* readers may be blocked waiting for us to go online */
	wake_up(&dev->read_wq);
	return 0;
}

static void acc_function_disable(struct usb_function *f)
{
	struct acc_dev	*dev = func_to_dev(f);
	struct usb_composite_dev	*cdev = dev->cdev;

	DBG(cdev, "acc_function_disable\n");
	acc_set_disconnected(dev);
	usb_ep_disable(dev->ep_in);
	usb_ep_disable(dev->ep_out);

	/* readers may be blocked waiting for us to go online */
	wake_up(&dev->read_wq);

	VDBG(cdev, "%s disabled\n", dev->function.name);
}

static int acc_bind_config(struct usb_configuration *c)
{
	struct acc_dev *dev = _acc_dev;
	int ret;

	printk(KERN_INFO "acc_bind_config\n");

	/* allocate a string ID for our interface */
	if (acc_string_defs[INTERFACE_STRING_INDEX].id == 0) {
		ret = usb_string_id(c->cdev);
		if (ret < 0)
			return ret;
		acc_string_defs[INTERFACE_STRING_INDEX].id = ret;
		acc_interface_desc.iInterface = ret;
	}

	dev->cdev = c->cdev;
	dev->function.name = "accessory";
	dev->function.strings = acc_strings,
	dev->function.descriptors = fs_acc_descs;
	dev->function.hs_descriptors = hs_acc_descs;
	dev->function.bind = acc_function_bind;
	dev->function.unbind = acc_function_unbind;
	dev->function.set_alt = acc_function_set_alt;
	dev->function.disable = acc_function_disable;

	return usb_add_function(c, &dev->function);
}

static int acc_setup(void)
{
	struct acc_dev *dev;
	int ret;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return -ENOMEM;

	spin_lock_init(&dev->lock);
	init_waitqueue_head(&dev->read_wq);
	init_waitqueue_head(&dev->write_wq);
	atomic_set(&dev->open_excl, 0);
	INIT_LIST_HEAD(&dev->tx_idle);
	INIT_LIST_HEAD(&dev->hid_list);
	INIT_LIST_HEAD(&dev->new_hid_list);
	INIT_LIST_HEAD(&dev->dead_hid_list);
	INIT_DELAYED_WORK(&dev->start_work, acc_start_work);
	INIT_WORK(&dev->hid_work, acc_hid_work);

	/* _acc_dev must be set before calling usb_gadget_register_driver */
	_acc_dev = dev;

	ret = misc_register(&acc_device);
	if (ret)
		goto err;

	return 0;

err:
	kfree(dev);
	pr_err("USB accessory gadget driver failed to initialize\n");
	return ret;
}

static void acc_disconnect(void)
{
	/* unregister all HID devices if USB is disconnected */
	kill_all_hid_devices(_acc_dev);
}

static void acc_cleanup(void)
{
	misc_deregister(&acc_device);
	kfree(_acc_dev);
	_acc_dev = NULL;
}