aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/usb/gadget/f_uac2.c
blob: 03c1fb686644e02d34b5b0f4a9c8e847d6a6de27 (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
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
/*
 * f_uac2.c -- USB Audio Class 2.0 Function
 *
 * Copyright (C) 2011
 *    Yadwinder Singh (yadi.brar01@gmail.com)
 *    Jaswinder Singh (jaswinder.singh@linaro.org)
 *
 * 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.
 */

#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>
#include <linux/platform_device.h>
#include <linux/module.h>

#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>

/* Playback(USB-IN) Default Stereo - Fl/Fr */
static int p_chmask = 0x3;
module_param(p_chmask, uint, S_IRUGO);
MODULE_PARM_DESC(p_chmask, "Playback Channel Mask");

/* Playback Default 48 KHz */
static int p_srate = 48000;
module_param(p_srate, uint, S_IRUGO);
MODULE_PARM_DESC(p_srate, "Playback Sampling Rate");

/* Playback Default 16bits/sample */
static int p_ssize = 2;
module_param(p_ssize, uint, S_IRUGO);
MODULE_PARM_DESC(p_ssize, "Playback Sample Size(bytes)");

/* Capture(USB-OUT) Default Stereo - Fl/Fr */
static int c_chmask = 0x3;
module_param(c_chmask, uint, S_IRUGO);
MODULE_PARM_DESC(c_chmask, "Capture Channel Mask");

/* Capture Default 64 KHz */
static int c_srate = 64000;
module_param(c_srate, uint, S_IRUGO);
MODULE_PARM_DESC(c_srate, "Capture Sampling Rate");

/* Capture Default 16bits/sample */
static int c_ssize = 2;
module_param(c_ssize, uint, S_IRUGO);
MODULE_PARM_DESC(c_ssize, "Capture Sample Size(bytes)");

/* Keep everyone on toes */
#define USB_XFERS	2

/*
 * The driver implements a simple UAC_2 topology.
 * USB-OUT -> IT_1 -> OT_3 -> ALSA_Capture
 * ALSA_Playback -> IT_2 -> OT_4 -> USB-IN
 * Capture and Playback sampling rates are independently
 *  controlled by two clock sources :
 *    CLK_5 := c_srate, and CLK_6 := p_srate
 */
#define USB_OUT_IT_ID	1
#define IO_IN_IT_ID	2
#define IO_OUT_OT_ID	3
#define USB_IN_OT_ID	4
#define USB_OUT_CLK_ID	5
#define USB_IN_CLK_ID	6

#define CONTROL_ABSENT	0
#define CONTROL_RDONLY	1
#define CONTROL_RDWR	3

#define CLK_FREQ_CTRL	0
#define CLK_VLD_CTRL	2

#define COPY_CTRL	0
#define CONN_CTRL	2
#define OVRLD_CTRL	4
#define CLSTR_CTRL	6
#define UNFLW_CTRL	8
#define OVFLW_CTRL	10

const char *uac2_name = "snd_uac2";

struct uac2_req {
	struct uac2_rtd_params *pp; /* parent param */
	struct usb_request *req;
};

struct uac2_rtd_params {
	bool ep_enabled; /* if the ep is enabled */
	/* Size of the ring buffer */
	size_t dma_bytes;
	unsigned char *dma_area;

	struct snd_pcm_substream *ss;

	/* Ring buffer */
	ssize_t hw_ptr;

	void *rbuf;

	size_t period_size;

	unsigned max_psize;
	struct uac2_req ureq[USB_XFERS];

	spinlock_t lock;
};

struct snd_uac2_chip {
	struct platform_device pdev;
	struct platform_driver pdrv;

	struct uac2_rtd_params p_prm;
	struct uac2_rtd_params c_prm;

	struct snd_card *card;
	struct snd_pcm *pcm;
};

#define BUFF_SIZE_MAX	(PAGE_SIZE * 16)
#define PRD_SIZE_MAX	PAGE_SIZE
#define MIN_PERIODS	4

static struct snd_pcm_hardware uac2_pcm_hardware = {
	.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER
		 | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID
		 | SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME,
	.rates = SNDRV_PCM_RATE_CONTINUOUS,
	.periods_max = BUFF_SIZE_MAX / PRD_SIZE_MAX,
	.buffer_bytes_max = BUFF_SIZE_MAX,
	.period_bytes_max = PRD_SIZE_MAX,
	.periods_min = MIN_PERIODS,
};

struct audio_dev {
	u8 ac_intf, ac_alt;
	u8 as_out_intf, as_out_alt;
	u8 as_in_intf, as_in_alt;

	struct usb_ep *in_ep, *out_ep;
	struct usb_function func;

	/* The ALSA Sound Card it represents on the USB-Client side */
	struct snd_uac2_chip uac2;
};

static struct audio_dev *agdev_g;

static inline
struct audio_dev *func_to_agdev(struct usb_function *f)
{
	return container_of(f, struct audio_dev, func);
}

static inline
struct audio_dev *uac2_to_agdev(struct snd_uac2_chip *u)
{
	return container_of(u, struct audio_dev, uac2);
}

static inline
struct snd_uac2_chip *pdev_to_uac2(struct platform_device *p)
{
	return container_of(p, struct snd_uac2_chip, pdev);
}

static inline
struct snd_uac2_chip *prm_to_uac2(struct uac2_rtd_params *r)
{
	struct snd_uac2_chip *uac2 = container_of(r,
					struct snd_uac2_chip, c_prm);

	if (&uac2->c_prm != r)
		uac2 = container_of(r, struct snd_uac2_chip, p_prm);

	return uac2;
}

static inline
uint num_channels(uint chanmask)
{
	uint num = 0;

	while (chanmask) {
		num += (chanmask & 1);
		chanmask >>= 1;
	}

	return num;
}

static void
agdev_iso_complete(struct usb_ep *ep, struct usb_request *req)
{
	unsigned pending;
	unsigned long flags;
	bool update_alsa = false;
	unsigned char *src, *dst;
	int status = req->status;
	struct uac2_req *ur = req->context;
	struct snd_pcm_substream *substream;
	struct uac2_rtd_params *prm = ur->pp;
	struct snd_uac2_chip *uac2 = prm_to_uac2(prm);

	/* i/f shutting down */
	if (!prm->ep_enabled)
		return;

	/*
	 * We can't really do much about bad xfers.
	 * Afterall, the ISOCH xfers could fail legitimately.
	 */
	if (status)
		pr_debug("%s: iso_complete status(%d) %d/%d\n",
			__func__, status, req->actual, req->length);

	substream = prm->ss;

	/* Do nothing if ALSA isn't active */
	if (!substream)
		goto exit;

	spin_lock_irqsave(&prm->lock, flags);

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
		src = prm->dma_area + prm->hw_ptr;
		req->actual = req->length;
		dst = req->buf;
	} else {
		dst = prm->dma_area + prm->hw_ptr;
		src = req->buf;
	}

	pending = prm->hw_ptr % prm->period_size;
	pending += req->actual;
	if (pending >= prm->period_size)
		update_alsa = true;

	prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;

	spin_unlock_irqrestore(&prm->lock, flags);

	/* Pack USB load in ALSA ring buffer */
	memcpy(dst, src, req->actual);
exit:
	if (usb_ep_queue(ep, req, GFP_ATOMIC))
		dev_err(&uac2->pdev.dev, "%d Error!\n", __LINE__);

	if (update_alsa)
		snd_pcm_period_elapsed(substream);

	return;
}

static int
uac2_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
	struct uac2_rtd_params *prm;
	unsigned long flags;
	int err = 0;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		prm = &uac2->p_prm;
	else
		prm = &uac2->c_prm;

	spin_lock_irqsave(&prm->lock, flags);

	/* Reset */
	prm->hw_ptr = 0;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
		prm->ss = substream;
		break;
	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
		prm->ss = NULL;
		break;
	default:
		err = -EINVAL;
	}

	spin_unlock_irqrestore(&prm->lock, flags);

	/* Clear buffer after Play stops */
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && !prm->ss)
		memset(prm->rbuf, 0, prm->max_psize * USB_XFERS);

	return err;
}

static snd_pcm_uframes_t uac2_pcm_pointer(struct snd_pcm_substream *substream)
{
	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
	struct uac2_rtd_params *prm;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		prm = &uac2->p_prm;
	else
		prm = &uac2->c_prm;

	return bytes_to_frames(substream->runtime, prm->hw_ptr);
}

static int uac2_pcm_hw_params(struct snd_pcm_substream *substream,
			       struct snd_pcm_hw_params *hw_params)
{
	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
	struct uac2_rtd_params *prm;
	int err;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		prm = &uac2->p_prm;
	else
		prm = &uac2->c_prm;

	err = snd_pcm_lib_malloc_pages(substream,
					params_buffer_bytes(hw_params));
	if (err >= 0) {
		prm->dma_bytes = substream->runtime->dma_bytes;
		prm->dma_area = substream->runtime->dma_area;
		prm->period_size = params_period_bytes(hw_params);
	}

	return err;
}

static int uac2_pcm_hw_free(struct snd_pcm_substream *substream)
{
	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
	struct uac2_rtd_params *prm;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		prm = &uac2->p_prm;
	else
		prm = &uac2->c_prm;

	prm->dma_area = NULL;
	prm->dma_bytes = 0;
	prm->period_size = 0;

	return snd_pcm_lib_free_pages(substream);
}

static int uac2_pcm_open(struct snd_pcm_substream *substream)
{
	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;

	runtime->hw = uac2_pcm_hardware;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
		spin_lock_init(&uac2->p_prm.lock);
		runtime->hw.rate_min = p_srate;
		runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE; /* ! p_ssize ! */
		runtime->hw.channels_min = num_channels(p_chmask);
		runtime->hw.period_bytes_min = 2 * uac2->p_prm.max_psize
						/ runtime->hw.periods_min;
	} else {
		spin_lock_init(&uac2->c_prm.lock);
		runtime->hw.rate_min = c_srate;
		runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE; /* ! c_ssize ! */
		runtime->hw.channels_min = num_channels(c_chmask);
		runtime->hw.period_bytes_min = 2 * uac2->c_prm.max_psize
						/ runtime->hw.periods_min;
	}

	runtime->hw.rate_max = runtime->hw.rate_min;
	runtime->hw.channels_max = runtime->hw.channels_min;

	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);

	return 0;
}

/* ALSA cries without these function pointers */
static int uac2_pcm_null(struct snd_pcm_substream *substream)
{
	return 0;
}

static struct snd_pcm_ops uac2_pcm_ops = {
	.open = uac2_pcm_open,
	.close = uac2_pcm_null,
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = uac2_pcm_hw_params,
	.hw_free = uac2_pcm_hw_free,
	.trigger = uac2_pcm_trigger,
	.pointer = uac2_pcm_pointer,
	.prepare = uac2_pcm_null,
};

static int snd_uac2_probe(struct platform_device *pdev)
{
	struct snd_uac2_chip *uac2 = pdev_to_uac2(pdev);
	struct snd_card *card;
	struct snd_pcm *pcm;
	int err;

	/* Choose any slot, with no id */
	err = snd_card_create(-1, NULL, THIS_MODULE, 0, &card);
	if (err < 0)
		return err;

	uac2->card = card;

	/*
	 * Create first PCM device
	 * Create a substream only for non-zero channel streams
	 */
	err = snd_pcm_new(uac2->card, "UAC2 PCM", 0,
			       p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);
	if (err < 0)
		goto snd_fail;

	strcpy(pcm->name, "UAC2 PCM");
	pcm->private_data = uac2;

	uac2->pcm = pcm;

	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac2_pcm_ops);
	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac2_pcm_ops);

	strcpy(card->driver, "UAC2_Gadget");
	strcpy(card->shortname, "UAC2_Gadget");
	sprintf(card->longname, "UAC2_Gadget %i", pdev->id);

	snd_card_set_dev(card, &pdev->dev);

	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
		snd_dma_continuous_data(GFP_KERNEL), 0, BUFF_SIZE_MAX);

	err = snd_card_register(card);
	if (!err) {
		platform_set_drvdata(pdev, card);
		return 0;
	}

snd_fail:
	snd_card_free(card);

	uac2->pcm = NULL;
	uac2->card = NULL;

	return err;
}

static int snd_uac2_remove(struct platform_device *pdev)
{
	struct snd_card *card = platform_get_drvdata(pdev);

	if (card)
		return snd_card_free(card);

	return 0;
}

static int alsa_uac2_init(struct audio_dev *agdev)
{
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	int err;

	uac2->pdrv.probe = snd_uac2_probe;
	uac2->pdrv.remove = snd_uac2_remove;
	uac2->pdrv.driver.name = uac2_name;

	uac2->pdev.id = 0;
	uac2->pdev.name = uac2_name;

	/* Register snd_uac2 driver */
	err = platform_driver_register(&uac2->pdrv);
	if (err)
		return err;

	/* Register snd_uac2 device */
	err = platform_device_register(&uac2->pdev);
	if (err)
		platform_driver_unregister(&uac2->pdrv);

	return err;
}

static void alsa_uac2_exit(struct audio_dev *agdev)
{
	struct snd_uac2_chip *uac2 = &agdev->uac2;

	platform_driver_unregister(&uac2->pdrv);
	platform_device_unregister(&uac2->pdev);
}


/* --------- USB Function Interface ------------- */

enum {
	STR_ASSOC,
	STR_IF_CTRL,
	STR_CLKSRC_IN,
	STR_CLKSRC_OUT,
	STR_USB_IT,
	STR_IO_IT,
	STR_USB_OT,
	STR_IO_OT,
	STR_AS_OUT_ALT0,
	STR_AS_OUT_ALT1,
	STR_AS_IN_ALT0,
	STR_AS_IN_ALT1,
};

static char clksrc_in[8];
static char clksrc_out[8];

static struct usb_string strings_fn[] = {
	[STR_ASSOC].s = "Source/Sink",
	[STR_IF_CTRL].s = "Topology Control",
	[STR_CLKSRC_IN].s = clksrc_in,
	[STR_CLKSRC_OUT].s = clksrc_out,
	[STR_USB_IT].s = "USBH Out",
	[STR_IO_IT].s = "USBD Out",
	[STR_USB_OT].s = "USBH In",
	[STR_IO_OT].s = "USBD In",
	[STR_AS_OUT_ALT0].s = "Playback Inactive",
	[STR_AS_OUT_ALT1].s = "Playback Active",
	[STR_AS_IN_ALT0].s = "Capture Inactive",
	[STR_AS_IN_ALT1].s = "Capture Active",
	{ },
};

static struct usb_gadget_strings str_fn = {
	.language = 0x0409,	/* en-us */
	.strings = strings_fn,
};

static struct usb_gadget_strings *fn_strings[] = {
	&str_fn,
	NULL,
};

static struct usb_qualifier_descriptor devqual_desc = {
	.bLength = sizeof devqual_desc,
	.bDescriptorType = USB_DT_DEVICE_QUALIFIER,

	.bcdUSB = cpu_to_le16(0x200),
	.bDeviceClass = USB_CLASS_MISC,
	.bDeviceSubClass = 0x02,
	.bDeviceProtocol = 0x01,
	.bNumConfigurations = 1,
	.bRESERVED = 0,
};

static struct usb_interface_assoc_descriptor iad_desc = {
	.bLength = sizeof iad_desc,
	.bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,

	.bFirstInterface = 0,
	.bInterfaceCount = 3,
	.bFunctionClass = USB_CLASS_AUDIO,
	.bFunctionSubClass = UAC2_FUNCTION_SUBCLASS_UNDEFINED,
	.bFunctionProtocol = UAC_VERSION_2,
};

/* Audio Control Interface */
static struct usb_interface_descriptor std_ac_if_desc = {
	.bLength = sizeof std_ac_if_desc,
	.bDescriptorType = USB_DT_INTERFACE,

	.bAlternateSetting = 0,
	.bNumEndpoints = 0,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL,
	.bInterfaceProtocol = UAC_VERSION_2,
};

/* Clock source for IN traffic */
struct uac_clock_source_descriptor in_clk_src_desc = {
	.bLength = sizeof in_clk_src_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC2_CLOCK_SOURCE,
	.bClockID = USB_IN_CLK_ID,
	.bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
	.bmControls = (CONTROL_RDONLY << CLK_FREQ_CTRL),
	.bAssocTerminal = 0,
};

/* Clock source for OUT traffic */
struct uac_clock_source_descriptor out_clk_src_desc = {
	.bLength = sizeof out_clk_src_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC2_CLOCK_SOURCE,
	.bClockID = USB_OUT_CLK_ID,
	.bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
	.bmControls = (CONTROL_RDONLY << CLK_FREQ_CTRL),
	.bAssocTerminal = 0,
};

/* Input Terminal for USB_OUT */
struct uac2_input_terminal_descriptor usb_out_it_desc = {
	.bLength = sizeof usb_out_it_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_INPUT_TERMINAL,
	.bTerminalID = USB_OUT_IT_ID,
	.wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
	.bAssocTerminal = 0,
	.bCSourceID = USB_OUT_CLK_ID,
	.iChannelNames = 0,
	.bmControls = (CONTROL_RDWR << COPY_CTRL),
};

/* Input Terminal for I/O-In */
struct uac2_input_terminal_descriptor io_in_it_desc = {
	.bLength = sizeof io_in_it_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_INPUT_TERMINAL,
	.bTerminalID = IO_IN_IT_ID,
	.wTerminalType = cpu_to_le16(UAC_INPUT_TERMINAL_UNDEFINED),
	.bAssocTerminal = 0,
	.bCSourceID = USB_IN_CLK_ID,
	.iChannelNames = 0,
	.bmControls = (CONTROL_RDWR << COPY_CTRL),
};

/* Ouput Terminal for USB_IN */
struct uac2_output_terminal_descriptor usb_in_ot_desc = {
	.bLength = sizeof usb_in_ot_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
	.bTerminalID = USB_IN_OT_ID,
	.wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
	.bAssocTerminal = 0,
	.bSourceID = IO_IN_IT_ID,
	.bCSourceID = USB_IN_CLK_ID,
	.bmControls = (CONTROL_RDWR << COPY_CTRL),
};

/* Ouput Terminal for I/O-Out */
struct uac2_output_terminal_descriptor io_out_ot_desc = {
	.bLength = sizeof io_out_ot_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
	.bTerminalID = IO_OUT_OT_ID,
	.wTerminalType = cpu_to_le16(UAC_OUTPUT_TERMINAL_UNDEFINED),
	.bAssocTerminal = 0,
	.bSourceID = USB_OUT_IT_ID,
	.bCSourceID = USB_OUT_CLK_ID,
	.bmControls = (CONTROL_RDWR << COPY_CTRL),
};

struct uac2_ac_header_descriptor ac_hdr_desc = {
	.bLength = sizeof ac_hdr_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_MS_HEADER,
	.bcdADC = cpu_to_le16(0x200),
	.bCategory = UAC2_FUNCTION_IO_BOX,
	.wTotalLength = sizeof in_clk_src_desc + sizeof out_clk_src_desc
			 + sizeof usb_out_it_desc + sizeof io_in_it_desc
			+ sizeof usb_in_ot_desc + sizeof io_out_ot_desc,
	.bmControls = 0,
};

/* Audio Streaming OUT Interface - Alt0 */
static struct usb_interface_descriptor std_as_out_if0_desc = {
	.bLength = sizeof std_as_out_if0_desc,
	.bDescriptorType = USB_DT_INTERFACE,

	.bAlternateSetting = 0,
	.bNumEndpoints = 0,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
	.bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Streaming OUT Interface - Alt1 */
static struct usb_interface_descriptor std_as_out_if1_desc = {
	.bLength = sizeof std_as_out_if1_desc,
	.bDescriptorType = USB_DT_INTERFACE,

	.bAlternateSetting = 1,
	.bNumEndpoints = 1,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
	.bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Stream OUT Intface Desc */
struct uac2_as_header_descriptor as_out_hdr_desc = {
	.bLength = sizeof as_out_hdr_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_AS_GENERAL,
	.bTerminalLink = USB_OUT_IT_ID,
	.bmControls = 0,
	.bFormatType = UAC_FORMAT_TYPE_I,
	.bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
	.iChannelNames = 0,
};

/* Audio USB_OUT Format */
struct uac2_format_type_i_descriptor as_out_fmt1_desc = {
	.bLength = sizeof as_out_fmt1_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,
	.bDescriptorSubtype = UAC_FORMAT_TYPE,
	.bFormatType = UAC_FORMAT_TYPE_I,
};

/* STD AS ISO OUT Endpoint */
struct usb_endpoint_descriptor fs_epout_desc = {
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bEndpointAddress = USB_DIR_OUT,
	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
	.bInterval = 1,
};

struct usb_endpoint_descriptor hs_epout_desc = {
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
	.bInterval = 4,
};

/* CS AS ISO OUT Endpoint */
static struct uac2_iso_endpoint_descriptor as_iso_out_desc = {
	.bLength = sizeof as_iso_out_desc,
	.bDescriptorType = USB_DT_CS_ENDPOINT,

	.bDescriptorSubtype = UAC_EP_GENERAL,
	.bmAttributes = 0,
	.bmControls = 0,
	.bLockDelayUnits = 0,
	.wLockDelay = 0,
};

/* Audio Streaming IN Interface - Alt0 */
static struct usb_interface_descriptor std_as_in_if0_desc = {
	.bLength = sizeof std_as_in_if0_desc,
	.bDescriptorType = USB_DT_INTERFACE,

	.bAlternateSetting = 0,
	.bNumEndpoints = 0,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
	.bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Streaming IN Interface - Alt1 */
static struct usb_interface_descriptor std_as_in_if1_desc = {
	.bLength = sizeof std_as_in_if1_desc,
	.bDescriptorType = USB_DT_INTERFACE,

	.bAlternateSetting = 1,
	.bNumEndpoints = 1,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
	.bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Stream IN Intface Desc */
struct uac2_as_header_descriptor as_in_hdr_desc = {
	.bLength = sizeof as_in_hdr_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,

	.bDescriptorSubtype = UAC_AS_GENERAL,
	.bTerminalLink = USB_IN_OT_ID,
	.bmControls = 0,
	.bFormatType = UAC_FORMAT_TYPE_I,
	.bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
	.iChannelNames = 0,
};

/* Audio USB_IN Format */
struct uac2_format_type_i_descriptor as_in_fmt1_desc = {
	.bLength = sizeof as_in_fmt1_desc,
	.bDescriptorType = USB_DT_CS_INTERFACE,
	.bDescriptorSubtype = UAC_FORMAT_TYPE,
	.bFormatType = UAC_FORMAT_TYPE_I,
};

/* STD AS ISO IN Endpoint */
struct usb_endpoint_descriptor fs_epin_desc = {
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bEndpointAddress = USB_DIR_IN,
	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
	.bInterval = 1,
};

struct usb_endpoint_descriptor hs_epin_desc = {
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
	.bInterval = 4,
};

/* CS AS ISO IN Endpoint */
static struct uac2_iso_endpoint_descriptor as_iso_in_desc = {
	.bLength = sizeof as_iso_in_desc,
	.bDescriptorType = USB_DT_CS_ENDPOINT,

	.bDescriptorSubtype = UAC_EP_GENERAL,
	.bmAttributes = 0,
	.bmControls = 0,
	.bLockDelayUnits = 0,
	.wLockDelay = 0,
};

static struct usb_descriptor_header *fs_audio_desc[] = {
	(struct usb_descriptor_header *)&iad_desc,
	(struct usb_descriptor_header *)&std_ac_if_desc,

	(struct usb_descriptor_header *)&ac_hdr_desc,
	(struct usb_descriptor_header *)&in_clk_src_desc,
	(struct usb_descriptor_header *)&out_clk_src_desc,
	(struct usb_descriptor_header *)&usb_out_it_desc,
	(struct usb_descriptor_header *)&io_in_it_desc,
	(struct usb_descriptor_header *)&usb_in_ot_desc,
	(struct usb_descriptor_header *)&io_out_ot_desc,

	(struct usb_descriptor_header *)&std_as_out_if0_desc,
	(struct usb_descriptor_header *)&std_as_out_if1_desc,

	(struct usb_descriptor_header *)&as_out_hdr_desc,
	(struct usb_descriptor_header *)&as_out_fmt1_desc,
	(struct usb_descriptor_header *)&fs_epout_desc,
	(struct usb_descriptor_header *)&as_iso_out_desc,

	(struct usb_descriptor_header *)&std_as_in_if0_desc,
	(struct usb_descriptor_header *)&std_as_in_if1_desc,

	(struct usb_descriptor_header *)&as_in_hdr_desc,
	(struct usb_descriptor_header *)&as_in_fmt1_desc,
	(struct usb_descriptor_header *)&fs_epin_desc,
	(struct usb_descriptor_header *)&as_iso_in_desc,
	NULL,
};

static struct usb_descriptor_header *hs_audio_desc[] = {
	(struct usb_descriptor_header *)&iad_desc,
	(struct usb_descriptor_header *)&std_ac_if_desc,

	(struct usb_descriptor_header *)&ac_hdr_desc,
	(struct usb_descriptor_header *)&in_clk_src_desc,
	(struct usb_descriptor_header *)&out_clk_src_desc,
	(struct usb_descriptor_header *)&usb_out_it_desc,
	(struct usb_descriptor_header *)&io_in_it_desc,
	(struct usb_descriptor_header *)&usb_in_ot_desc,
	(struct usb_descriptor_header *)&io_out_ot_desc,

	(struct usb_descriptor_header *)&std_as_out_if0_desc,
	(struct usb_descriptor_header *)&std_as_out_if1_desc,

	(struct usb_descriptor_header *)&as_out_hdr_desc,
	(struct usb_descriptor_header *)&as_out_fmt1_desc,
	(struct usb_descriptor_header *)&hs_epout_desc,
	(struct usb_descriptor_header *)&as_iso_out_desc,

	(struct usb_descriptor_header *)&std_as_in_if0_desc,
	(struct usb_descriptor_header *)&std_as_in_if1_desc,

	(struct usb_descriptor_header *)&as_in_hdr_desc,
	(struct usb_descriptor_header *)&as_in_fmt1_desc,
	(struct usb_descriptor_header *)&hs_epin_desc,
	(struct usb_descriptor_header *)&as_iso_in_desc,
	NULL,
};

struct cntrl_cur_lay3 {
	__u32	dCUR;
};

struct cntrl_range_lay3 {
	__u16	wNumSubRanges;
	__u32	dMIN;
	__u32	dMAX;
	__u32	dRES;
} __packed;

static inline void
free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
{
	struct snd_uac2_chip *uac2 = prm_to_uac2(prm);
	int i;

	prm->ep_enabled = false;

	for (i = 0; i < USB_XFERS; i++) {
		if (prm->ureq[i].req) {
			usb_ep_dequeue(ep, prm->ureq[i].req);
			usb_ep_free_request(ep, prm->ureq[i].req);
			prm->ureq[i].req = NULL;
		}
	}

	if (usb_ep_disable(ep))
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
}

static int __init
afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
{
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	struct usb_composite_dev *cdev = cfg->cdev;
	struct usb_gadget *gadget = cdev->gadget;
	struct uac2_rtd_params *prm;
	int ret;

	ret = usb_interface_id(cfg, fn);
	if (ret < 0) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return ret;
	}
	std_ac_if_desc.bInterfaceNumber = ret;
	agdev->ac_intf = ret;
	agdev->ac_alt = 0;

	ret = usb_interface_id(cfg, fn);
	if (ret < 0) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return ret;
	}
	std_as_out_if0_desc.bInterfaceNumber = ret;
	std_as_out_if1_desc.bInterfaceNumber = ret;
	agdev->as_out_intf = ret;
	agdev->as_out_alt = 0;

	ret = usb_interface_id(cfg, fn);
	if (ret < 0) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return ret;
	}
	std_as_in_if0_desc.bInterfaceNumber = ret;
	std_as_in_if1_desc.bInterfaceNumber = ret;
	agdev->as_in_intf = ret;
	agdev->as_in_alt = 0;

	agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
	if (!agdev->out_ep) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		goto err;
	}
	agdev->out_ep->driver_data = agdev;

	agdev->in_ep = usb_ep_autoconfig(gadget, &fs_epin_desc);
	if (!agdev->in_ep) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		goto err;
	}
	agdev->in_ep->driver_data = agdev;

	hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
	hs_epout_desc.wMaxPacketSize = fs_epout_desc.wMaxPacketSize;
	hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
	hs_epin_desc.wMaxPacketSize = fs_epin_desc.wMaxPacketSize;

	ret = usb_assign_descriptors(fn, fs_audio_desc, hs_audio_desc, NULL);
	if (ret)
		goto err;

	prm = &agdev->uac2.c_prm;
	prm->max_psize = hs_epout_desc.wMaxPacketSize;
	prm->rbuf = kzalloc(prm->max_psize * USB_XFERS, GFP_KERNEL);
	if (!prm->rbuf) {
		prm->max_psize = 0;
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		goto err;
	}

	prm = &agdev->uac2.p_prm;
	prm->max_psize = hs_epin_desc.wMaxPacketSize;
	prm->rbuf = kzalloc(prm->max_psize * USB_XFERS, GFP_KERNEL);
	if (!prm->rbuf) {
		prm->max_psize = 0;
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		goto err;
	}

	ret = alsa_uac2_init(agdev);
	if (ret)
		goto err;
	return 0;
err:
	kfree(agdev->uac2.p_prm.rbuf);
	kfree(agdev->uac2.c_prm.rbuf);
	usb_free_all_descriptors(fn);
	if (agdev->in_ep)
		agdev->in_ep->driver_data = NULL;
	if (agdev->out_ep)
		agdev->out_ep->driver_data = NULL;
	return -EINVAL;
}

static void
afunc_unbind(struct usb_configuration *cfg, struct usb_function *fn)
{
	struct audio_dev *agdev = func_to_agdev(fn);
	struct uac2_rtd_params *prm;

	alsa_uac2_exit(agdev);

	prm = &agdev->uac2.p_prm;
	kfree(prm->rbuf);

	prm = &agdev->uac2.c_prm;
	kfree(prm->rbuf);
	usb_free_all_descriptors(fn);

	if (agdev->in_ep)
		agdev->in_ep->driver_data = NULL;
	if (agdev->out_ep)
		agdev->out_ep->driver_data = NULL;
}

static int
afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
{
	struct usb_composite_dev *cdev = fn->config->cdev;
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	struct usb_gadget *gadget = cdev->gadget;
	struct usb_request *req;
	struct usb_ep *ep;
	struct uac2_rtd_params *prm;
	int i;

	/* No i/f has more than 2 alt settings */
	if (alt > 1) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return -EINVAL;
	}

	if (intf == agdev->ac_intf) {
		/* Control I/f has only 1 AltSetting - 0 */
		if (alt) {
			dev_err(&uac2->pdev.dev,
				"%s:%d Error!\n", __func__, __LINE__);
			return -EINVAL;
		}
		return 0;
	}

	if (intf == agdev->as_out_intf) {
		ep = agdev->out_ep;
		prm = &uac2->c_prm;
		config_ep_by_speed(gadget, fn, ep);
		agdev->as_out_alt = alt;
	} else if (intf == agdev->as_in_intf) {
		ep = agdev->in_ep;
		prm = &uac2->p_prm;
		config_ep_by_speed(gadget, fn, ep);
		agdev->as_in_alt = alt;
	} else {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return -EINVAL;
	}

	if (alt == 0) {
		free_ep(prm, ep);
		return 0;
	}

	prm->ep_enabled = true;
	usb_ep_enable(ep);

	for (i = 0; i < USB_XFERS; i++) {
		if (prm->ureq[i].req) {
			if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
				dev_err(&uac2->pdev.dev, "%d Error!\n",
					__LINE__);
			continue;
		}

		req = usb_ep_alloc_request(ep, GFP_ATOMIC);
		if (req == NULL) {
			dev_err(&uac2->pdev.dev,
				"%s:%d Error!\n", __func__, __LINE__);
			return -EINVAL;
		}

		prm->ureq[i].req = req;
		prm->ureq[i].pp = prm;

		req->zero = 0;
		req->context = &prm->ureq[i];
		req->length = prm->max_psize;
		req->complete =	agdev_iso_complete;
		req->buf = prm->rbuf + i * req->length;

		if (usb_ep_queue(ep, req, GFP_ATOMIC))
			dev_err(&uac2->pdev.dev, "%d Error!\n", __LINE__);
	}

	return 0;
}

static int
afunc_get_alt(struct usb_function *fn, unsigned intf)
{
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;

	if (intf == agdev->ac_intf)
		return agdev->ac_alt;
	else if (intf == agdev->as_out_intf)
		return agdev->as_out_alt;
	else if (intf == agdev->as_in_intf)
		return agdev->as_in_alt;
	else
		dev_err(&uac2->pdev.dev,
			"%s:%d Invalid Interface %d!\n",
			__func__, __LINE__, intf);

	return -EINVAL;
}

static void
afunc_disable(struct usb_function *fn)
{
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;

	free_ep(&uac2->p_prm, agdev->in_ep);
	agdev->as_in_alt = 0;

	free_ep(&uac2->c_prm, agdev->out_ep);
	agdev->as_out_alt = 0;
}

static int
in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	struct usb_request *req = fn->config->cdev->req;
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	u16 w_length = le16_to_cpu(cr->wLength);
	u16 w_index = le16_to_cpu(cr->wIndex);
	u16 w_value = le16_to_cpu(cr->wValue);
	u8 entity_id = (w_index >> 8) & 0xff;
	u8 control_selector = w_value >> 8;
	int value = -EOPNOTSUPP;

	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
		struct cntrl_cur_lay3 c;

		if (entity_id == USB_IN_CLK_ID)
			c.dCUR = p_srate;
		else if (entity_id == USB_OUT_CLK_ID)
			c.dCUR = c_srate;

		value = min_t(unsigned, w_length, sizeof c);
		memcpy(req->buf, &c, value);
	} else if (control_selector == UAC2_CS_CONTROL_CLOCK_VALID) {
		*(u8 *)req->buf = 1;
		value = min_t(unsigned, w_length, 1);
	} else {
		dev_err(&uac2->pdev.dev,
			"%s:%d control_selector=%d TODO!\n",
			__func__, __LINE__, control_selector);
	}

	return value;
}

static int
in_rq_range(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	struct usb_request *req = fn->config->cdev->req;
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	u16 w_length = le16_to_cpu(cr->wLength);
	u16 w_index = le16_to_cpu(cr->wIndex);
	u16 w_value = le16_to_cpu(cr->wValue);
	u8 entity_id = (w_index >> 8) & 0xff;
	u8 control_selector = w_value >> 8;
	struct cntrl_range_lay3 r;
	int value = -EOPNOTSUPP;

	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
		if (entity_id == USB_IN_CLK_ID)
			r.dMIN = p_srate;
		else if (entity_id == USB_OUT_CLK_ID)
			r.dMIN = c_srate;
		else
			return -EOPNOTSUPP;

		r.dMAX = r.dMIN;
		r.dRES = 0;
		r.wNumSubRanges = 1;

		value = min_t(unsigned, w_length, sizeof r);
		memcpy(req->buf, &r, value);
	} else {
		dev_err(&uac2->pdev.dev,
			"%s:%d control_selector=%d TODO!\n",
			__func__, __LINE__, control_selector);
	}

	return value;
}

static int
ac_rq_in(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	if (cr->bRequest == UAC2_CS_CUR)
		return in_rq_cur(fn, cr);
	else if (cr->bRequest == UAC2_CS_RANGE)
		return in_rq_range(fn, cr);
	else
		return -EOPNOTSUPP;
}

static int
out_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	u16 w_length = le16_to_cpu(cr->wLength);
	u16 w_value = le16_to_cpu(cr->wValue);
	u8 control_selector = w_value >> 8;

	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ)
		return w_length;

	return -EOPNOTSUPP;
}

static int
setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	u16 w_index = le16_to_cpu(cr->wIndex);
	u8 intf = w_index & 0xff;

	if (intf != agdev->ac_intf) {
		dev_err(&uac2->pdev.dev,
			"%s:%d Error!\n", __func__, __LINE__);
		return -EOPNOTSUPP;
	}

	if (cr->bRequestType & USB_DIR_IN)
		return ac_rq_in(fn, cr);
	else if (cr->bRequest == UAC2_CS_CUR)
		return out_rq_cur(fn, cr);

	return -EOPNOTSUPP;
}

static int
afunc_setup(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
	struct usb_composite_dev *cdev = fn->config->cdev;
	struct audio_dev *agdev = func_to_agdev(fn);
	struct snd_uac2_chip *uac2 = &agdev->uac2;
	struct usb_request *req = cdev->req;
	u16 w_length = le16_to_cpu(cr->wLength);
	int value = -EOPNOTSUPP;

	/* Only Class specific requests are supposed to reach here */
	if ((cr->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS)
		return -EOPNOTSUPP;

	if ((cr->bRequestType & USB_RECIP_MASK) == USB_RECIP_INTERFACE)
		value = setup_rq_inf(fn, cr);
	else
		dev_err(&uac2->pdev.dev, "%s:%d Error!\n", __func__, __LINE__);

	if (value >= 0) {
		req->length = value;
		req->zero = value < w_length;
		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
		if (value < 0) {
			dev_err(&uac2->pdev.dev,
				"%s:%d Error!\n", __func__, __LINE__);
			req->status = 0;
		}
	}

	return value;
}

static int audio_bind_config(struct usb_configuration *cfg)
{
	int res;

	agdev_g = kzalloc(sizeof *agdev_g, GFP_KERNEL);
	if (agdev_g == NULL) {
		printk(KERN_ERR "Unable to allocate audio gadget\n");
		return -ENOMEM;
	}

	res = usb_string_ids_tab(cfg->cdev, strings_fn);
	if (res)
		return res;
	iad_desc.iFunction = strings_fn[STR_ASSOC].id;
	std_ac_if_desc.iInterface = strings_fn[STR_IF_CTRL].id;
	in_clk_src_desc.iClockSource = strings_fn[STR_CLKSRC_IN].id;
	out_clk_src_desc.iClockSource = strings_fn[STR_CLKSRC_OUT].id;
	usb_out_it_desc.iTerminal = strings_fn[STR_USB_IT].id;
	io_in_it_desc.iTerminal = strings_fn[STR_IO_IT].id;
	usb_in_ot_desc.iTerminal = strings_fn[STR_USB_OT].id;
	io_out_ot_desc.iTerminal = strings_fn[STR_IO_OT].id;
	std_as_out_if0_desc.iInterface = strings_fn[STR_AS_OUT_ALT0].id;
	std_as_out_if1_desc.iInterface = strings_fn[STR_AS_OUT_ALT1].id;
	std_as_in_if0_desc.iInterface = strings_fn[STR_AS_IN_ALT0].id;
	std_as_in_if1_desc.iInterface = strings_fn[STR_AS_IN_ALT1].id;

	agdev_g->func.name = "uac2_func";
	agdev_g->func.strings = fn_strings;
	agdev_g->func.bind = afunc_bind;
	agdev_g->func.unbind = afunc_unbind;
	agdev_g->func.set_alt = afunc_set_alt;
	agdev_g->func.get_alt = afunc_get_alt;
	agdev_g->func.disable = afunc_disable;
	agdev_g->func.setup = afunc_setup;

	/* Initialize the configurable parameters */
	usb_out_it_desc.bNrChannels = num_channels(c_chmask);
	usb_out_it_desc.bmChannelConfig = cpu_to_le32(c_chmask);
	io_in_it_desc.bNrChannels = num_channels(p_chmask);
	io_in_it_desc.bmChannelConfig = cpu_to_le32(p_chmask);
	as_out_hdr_desc.bNrChannels = num_channels(c_chmask);
	as_out_hdr_desc.bmChannelConfig = cpu_to_le32(c_chmask);
	as_in_hdr_desc.bNrChannels = num_channels(p_chmask);
	as_in_hdr_desc.bmChannelConfig = cpu_to_le32(p_chmask);
	as_out_fmt1_desc.bSubslotSize = c_ssize;
	as_out_fmt1_desc.bBitResolution = c_ssize * 8;
	as_in_fmt1_desc.bSubslotSize = p_ssize;
	as_in_fmt1_desc.bBitResolution = p_ssize * 8;

	snprintf(clksrc_in, sizeof(clksrc_in), "%uHz", p_srate);
	snprintf(clksrc_out, sizeof(clksrc_out), "%uHz", c_srate);

	res = usb_add_function(cfg, &agdev_g->func);
	if (res < 0)
		kfree(agdev_g);

	return res;
}

static void
uac2_unbind_config(struct usb_configuration *cfg)
{
	kfree(agdev_g);
	agdev_g = NULL;
}