summaryrefslogtreecommitdiff
path: root/sound/usb/mixer_scarlett.c
blob: 49fcd25054439a05244afd30db79282353b4a943 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Scarlett Driver for ALSA
 *
 *   Copyright (c) 2013 by Tobias Hoffmann
 *   Copyright (c) 2013 by Robin Gareus <robin at gareus.org>
 *   Copyright (c) 2002 by Takashi Iwai <tiwai at suse.de>
 *   Copyright (c) 2014 by Chris J Arges <chris.j.arges at canonical.com>
 *
 *   Many codes borrowed from audio.c by
 *	    Alan Cox (alan at lxorguk.ukuu.org.uk)
 *	    Thomas Sailer (sailer at ife.ee.ethz.ch)
 *
 *   Code cleanup:
 *   David Henningsson <david.henningsson at canonical.com>
 */

/*
 * Rewritten and extended to support more models, e.g. Scarlett 18i8.
 *
 * Auto-detection via UAC2 is not feasible to properly discover the vast
 * majority of features. It's related to both Linux/ALSA's UAC2 as well as
 * Focusrite's implementation of it. Eventually quirks may be sufficient but
 * right now it's a major headache to work arount these things.
 *
 * NB. Neither the OSX nor the win driver provided by Focusrite performs
 * discovery, they seem to operate the same as this driver.
 */

/* Mixer Interface for the Focusrite Scarlett 18i6 audio interface.
 *
 * The protocol was reverse engineered by looking at communication between
 * Scarlett MixControl (v 1.2.128.0) and the Focusrite(R) Scarlett 18i6
 * (firmware v305) using wireshark and usbmon in January 2013.
 * Extended in July 2013.
 *
 * this mixer gives complete access to all features of the device:
 *  - change Impedance of inputs (Line-in, Mic / Instrument, Hi-Z)
 *  - select clock source
 *  - dynamic input to mixer-matrix assignment
 *  - 18 x 6 mixer-matrix gain stages
 *  - bus routing & volume control
 *  - automatic re-initialization on connect if device was power-cycled
 *
 * USB URB commands overview (bRequest = 0x01 = UAC2_CS_CUR)
 * wIndex
 * 0x01 Analog Input line/instrument impedance switch, wValue=0x0901 +
 *      channel, data=Line/Inst (2bytes)
 *      pad (-10dB) switch, wValue=0x0b01 + channel, data=Off/On (2bytes)
 *      ?? wValue=0x0803/04, ?? (2bytes)
 * 0x0a Master Volume, wValue=0x0200+bus[0:all + only 1..4?] data(2bytes)
 *      Bus Mute/Unmute wValue=0x0100+bus[0:all + only 1..4?], data(2bytes)
 * 0x28 Clock source, wValue=0x0100, data={1:int,2:spdif,3:adat} (1byte)
 * 0x29 Set Sample-rate, wValue=0x0100, data=sample-rate(4bytes)
 * 0x32 Mixer mux, wValue=0x0600 + mixer-channel, data=input-to-connect(2bytes)
 * 0x33 Output mux, wValue=bus, data=input-to-connect(2bytes)
 * 0x34 Capture mux, wValue=0...18, data=input-to-connect(2bytes)
 * 0x3c Matrix Mixer gains, wValue=mixer-node  data=gain(2bytes)
 *      ?? [sometimes](4bytes, e.g 0x000003be 0x000003bf ...03ff)
 *
 * USB reads: (i.e. actually issued by original software)
 * 0x01 wValue=0x0901+channel (1byte!!), wValue=0x0b01+channed (1byte!!)
 * 0x29 wValue=0x0100 sample-rate(4bytes)
 *      wValue=0x0200 ?? 1byte (only once)
 * 0x2a wValue=0x0100 ?? 4bytes, sample-rate2 ??
 *
 * USB reads with bRequest = 0x03 = UAC2_CS_MEM
 * 0x3c wValue=0x0002 1byte: sync status (locked=1)
 *      wValue=0x0000 18*2byte: peak meter (inputs)
 *      wValue=0x0001 8(?)*2byte: peak meter (mix)
 *      wValue=0x0003 6*2byte: peak meter (pcm/daw)
 *
 * USB write with bRequest = 0x03
 * 0x3c Save settings to hardware: wValue=0x005a, data=0xa5
 *
 *
 * <ditaa>
 *  /--------------\    18chn            6chn    /--------------\
 *  | Hardware  in +--+-------\        /------+--+ ALSA PCM out |
 *  \--------------/  |       |        |      |  \--------------/
 *                    |       |        |      |
 *                    |       v        v      |
 *                    |   +---------------+   |
 *                    |    \ Matrix  Mux /    |
 *                    |     +-----+-----+     |
 *                    |           |           |
 *                    |           | 18chn     |
 *                    |           v           |
 *                    |     +-----------+     |
 *                    |     | Mixer     |     |
 *                    |     |    Matrix |     |
 *                    |     |           |     |
 *                    |     | 18x6 Gain |     |
 *                    |     |   stages  |     |
 *                    |     +-----+-----+     |
 *                    |           |           |
 *                    |           |           |
 *                    | 18chn     | 6chn      | 6chn
 *                    v           v           v
 *                    =========================
 *             +---------------+     +--—------------+
 *              \ Output  Mux /       \ Capture Mux /
 *               +-----+-----+         +-----+-----+
 *                     |                     |
 *                     | 6chn                |
 *                     v                     |
 *              +-------------+              |
 *              | Master Gain |              |
 *              +------+------+              |
 *                     |                     |
 *                     | 6chn                | 18chn
 *                     | (3 stereo pairs)    |
 *  /--------------\   |                     |   /--------------\
 *  | Hardware out |<--/                     \-->| ALSA PCM  in |
 *  \--------------/                             \--------------/
 * </ditaa>
 *
 */

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

#include <sound/core.h>
#include <sound/control.h>
#include <sound/tlv.h>

#include "usbaudio.h"
#include "mixer.h"
#include "helper.h"
#include "power.h"

#include "mixer_scarlett.h"

/* some gui mixers can't handle negative ctl values */
#define SND_SCARLETT_LEVEL_BIAS 128
#define SND_SCARLETT_MATRIX_IN_MAX 18
#define SND_SCARLETT_CONTROLS_MAX 10
#define SND_SCARLETT_OFFSETS_MAX 5

enum {
	SCARLETT_OUTPUTS,
	SCARLETT_SWITCH_IMPEDANCE,
	SCARLETT_SWITCH_PAD,
	SCARLETT_SWITCH_GAIN,
};

enum {
	SCARLETT_OFFSET_PCM = 0,
	SCARLETT_OFFSET_ANALOG = 1,
	SCARLETT_OFFSET_SPDIF = 2,
	SCARLETT_OFFSET_ADAT = 3,
	SCARLETT_OFFSET_MIX = 4,
};

struct scarlett_mixer_elem_enum_info {
	int start;
	int len;
	int offsets[SND_SCARLETT_OFFSETS_MAX];
	char const * const *names;
};

struct scarlett_mixer_control {
	unsigned char num;
	unsigned char type;
	const char *name;
};

struct scarlett_device_info {
	int matrix_in;
	int matrix_out;
	int input_len;
	int output_len;

	struct scarlett_mixer_elem_enum_info opt_master;
	struct scarlett_mixer_elem_enum_info opt_matrix;

	/* initial values for matrix mux */
	int matrix_mux_init[SND_SCARLETT_MATRIX_IN_MAX];

	int num_controls;	/* number of items in controls */
	const struct scarlett_mixer_control controls[SND_SCARLETT_CONTROLS_MAX];
};

/********************** Enum Strings *************************/

static const struct scarlett_mixer_elem_enum_info opt_pad = {
	.start = 0,
	.len = 2,
	.offsets = {},
	.names = (char const * const []){
		"0dB", "-10dB"
	}
};

static const struct scarlett_mixer_elem_enum_info opt_gain = {
	.start = 0,
	.len = 2,
	.offsets = {},
	.names = (char const * const []){
		"Lo", "Hi"
	}
};

static const struct scarlett_mixer_elem_enum_info opt_impedance = {
	.start = 0,
	.len = 2,
	.offsets = {},
	.names = (char const * const []){
		"Line", "Hi-Z"
	}
};

static const struct scarlett_mixer_elem_enum_info opt_clock = {
	.start = 1,
	.len = 3,
	.offsets = {},
	.names = (char const * const []){
		"Internal", "SPDIF", "ADAT"
	}
};

static const struct scarlett_mixer_elem_enum_info opt_sync = {
	.start = 0,
	.len = 2,
	.offsets = {},
	.names = (char const * const []){
		"No Lock", "Locked"
	}
};

static int scarlett_ctl_switch_info(struct snd_kcontrol *kctl,
		struct snd_ctl_elem_info *uinfo)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;

	uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
	uinfo->count = elem->channels;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = 1;
	return 0;
}

static int scarlett_ctl_switch_get(struct snd_kcontrol *kctl,
		struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	int i, err, val;

	for (i = 0; i < elem->channels; i++) {
		err = snd_usb_get_cur_mix_value(elem, i, i, &val);
		if (err < 0)
			return err;

		val = !val; /* invert mute logic for mixer */
		ucontrol->value.integer.value[i] = val;
	}

	return 0;
}

static int scarlett_ctl_switch_put(struct snd_kcontrol *kctl,
		struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	int i, changed = 0;
	int err, oval, val;

	for (i = 0; i < elem->channels; i++) {
		err = snd_usb_get_cur_mix_value(elem, i, i, &oval);
		if (err < 0)
			return err;

		val = ucontrol->value.integer.value[i];
		val = !val;
		if (oval != val) {
			err = snd_usb_set_cur_mix_value(elem, i, i, val);
			if (err < 0)
				return err;

			changed = 1;
		}
	}

	return changed;
}

static int scarlett_ctl_resume(struct usb_mixer_elem_list *list)
{
	struct usb_mixer_elem_info *elem = mixer_elem_list_to_info(list);
	int i;

	for (i = 0; i < elem->channels; i++)
		if (elem->cached & (1 << i))
			snd_usb_set_cur_mix_value(elem, i, i,
						  elem->cache_val[i]);
	return 0;
}

static int scarlett_ctl_info(struct snd_kcontrol *kctl,
			     struct snd_ctl_elem_info *uinfo)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;

	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = elem->channels;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = (int)kctl->private_value +
		SND_SCARLETT_LEVEL_BIAS;
	uinfo->value.integer.step = 1;
	return 0;
}

static int scarlett_ctl_get(struct snd_kcontrol *kctl,
			    struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	int i, err, val;

	for (i = 0; i < elem->channels; i++) {
		err = snd_usb_get_cur_mix_value(elem, i, i, &val);
		if (err < 0)
			return err;

		val = clamp(val / 256, -128, (int)kctl->private_value) +
				    SND_SCARLETT_LEVEL_BIAS;
		ucontrol->value.integer.value[i] = val;
	}

	return 0;
}

static int scarlett_ctl_put(struct snd_kcontrol *kctl,
			    struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	int i, changed = 0;
	int err, oval, val;

	for (i = 0; i < elem->channels; i++) {
		err = snd_usb_get_cur_mix_value(elem, i, i, &oval);
		if (err < 0)
			return err;

		val = ucontrol->value.integer.value[i] -
			SND_SCARLETT_LEVEL_BIAS;
		val = val * 256;
		if (oval != val) {
			err = snd_usb_set_cur_mix_value(elem, i, i, val);
			if (err < 0)
				return err;

			changed = 1;
		}
	}

	return changed;
}

static void scarlett_generate_name(int i, char *dst, int offsets[])
{
	if (i > offsets[SCARLETT_OFFSET_MIX])
		sprintf(dst, "Mix %c",
			'A'+(i - offsets[SCARLETT_OFFSET_MIX] - 1));
	else if (i > offsets[SCARLETT_OFFSET_ADAT])
		sprintf(dst, "ADAT %d", i - offsets[SCARLETT_OFFSET_ADAT]);
	else if (i > offsets[SCARLETT_OFFSET_SPDIF])
		sprintf(dst, "SPDIF %d", i - offsets[SCARLETT_OFFSET_SPDIF]);
	else if (i > offsets[SCARLETT_OFFSET_ANALOG])
		sprintf(dst, "Analog %d", i - offsets[SCARLETT_OFFSET_ANALOG]);
	else if (i > offsets[SCARLETT_OFFSET_PCM])
		sprintf(dst, "PCM %d", i - offsets[SCARLETT_OFFSET_PCM]);
	else
		sprintf(dst, "Off");
}

static int scarlett_ctl_enum_dynamic_info(struct snd_kcontrol *kctl,
					  struct snd_ctl_elem_info *uinfo)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	struct scarlett_mixer_elem_enum_info *opt = elem->private_data;
	unsigned int items = opt->len;

	uinfo->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
	uinfo->count = elem->channels;
	uinfo->value.enumerated.items = items;

	if (uinfo->value.enumerated.item >= items)
		uinfo->value.enumerated.item = items - 1;

	/* generate name dynamically based on item number and offset info */
	scarlett_generate_name(uinfo->value.enumerated.item,
			       uinfo->value.enumerated.name,
			       opt->offsets);

	return 0;
}

static int scarlett_ctl_enum_info(struct snd_kcontrol *kctl,
				  struct snd_ctl_elem_info *uinfo)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	struct scarlett_mixer_elem_enum_info *opt = elem->private_data;

	return snd_ctl_enum_info(uinfo, elem->channels, opt->len,
				 (const char * const *)opt->names);
}

static int scarlett_ctl_enum_get(struct snd_kcontrol *kctl,
				 struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	struct scarlett_mixer_elem_enum_info *opt = elem->private_data;
	int err, val;

	err = snd_usb_get_cur_mix_value(elem, 0, 0, &val);
	if (err < 0)
		return err;

	val = clamp(val - opt->start, 0, opt->len-1);

	ucontrol->value.enumerated.item[0] = val;

	return 0;
}

static int scarlett_ctl_enum_put(struct snd_kcontrol *kctl,
				 struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	struct scarlett_mixer_elem_enum_info *opt = elem->private_data;
	int err, oval, val;

	err = snd_usb_get_cur_mix_value(elem, 0, 0, &oval);
	if (err < 0)
		return err;

	val = ucontrol->value.integer.value[0];
	val = val + opt->start;
	if (val != oval) {
		snd_usb_set_cur_mix_value(elem, 0, 0, val);
		return 1;
	}
	return 0;
}

static int scarlett_ctl_enum_resume(struct usb_mixer_elem_list *list)
{
	struct usb_mixer_elem_info *elem = mixer_elem_list_to_info(list);

	if (elem->cached)
		snd_usb_set_cur_mix_value(elem, 0, 0, *elem->cache_val);
	return 0;
}

static int scarlett_ctl_meter_get(struct snd_kcontrol *kctl,
				  struct snd_ctl_elem_value *ucontrol)
{
	struct usb_mixer_elem_info *elem = kctl->private_data;
	struct snd_usb_audio *chip = elem->head.mixer->chip;
	unsigned char buf[2 * MAX_CHANNELS] = {0, };
	int wValue = (elem->control << 8) | elem->idx_off;
	int idx = snd_usb_ctrl_intf(chip) | (elem->head.id << 8);
	int err;

	err = snd_usb_ctl_msg(chip->dev,
				usb_rcvctrlpipe(chip->dev, 0),
				UAC2_CS_MEM,
				USB_RECIP_INTERFACE | USB_TYPE_CLASS |
				USB_DIR_IN, wValue, idx, buf, elem->channels);
	if (err < 0)
		return err;

	ucontrol->value.enumerated.item[0] = clamp((int)buf[0], 0, 1);
	return 0;
}

static const struct snd_kcontrol_new usb_scarlett_ctl_switch = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "",
	.info = scarlett_ctl_switch_info,
	.get =  scarlett_ctl_switch_get,
	.put =  scarlett_ctl_switch_put,
};

static const DECLARE_TLV_DB_SCALE(db_scale_scarlett_gain, -12800, 100, 0);

static const struct snd_kcontrol_new usb_scarlett_ctl = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
		  SNDRV_CTL_ELEM_ACCESS_TLV_READ,
	.name = "",
	.info = scarlett_ctl_info,
	.get =  scarlett_ctl_get,
	.put =  scarlett_ctl_put,
	.private_value = 6,  /* max value */
	.tlv = { .p = db_scale_scarlett_gain }
};

static const struct snd_kcontrol_new usb_scarlett_ctl_master = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
		  SNDRV_CTL_ELEM_ACCESS_TLV_READ,
	.name = "",
	.info = scarlett_ctl_info,
	.get =  scarlett_ctl_get,
	.put =  scarlett_ctl_put,
	.private_value = 6,  /* max value */
	.tlv = { .p = db_scale_scarlett_gain }
};

static const struct snd_kcontrol_new usb_scarlett_ctl_enum = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "",
	.info = scarlett_ctl_enum_info,
	.get =  scarlett_ctl_enum_get,
	.put =  scarlett_ctl_enum_put,
};

static const struct snd_kcontrol_new usb_scarlett_ctl_dynamic_enum = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "",
	.info = scarlett_ctl_enum_dynamic_info,
	.get =  scarlett_ctl_enum_get,
	.put =  scarlett_ctl_enum_put,
};

static const struct snd_kcontrol_new usb_scarlett_ctl_sync = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.access = SNDRV_CTL_ELEM_ACCESS_READ | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
	.name = "",
	.info = scarlett_ctl_enum_info,
	.get =  scarlett_ctl_meter_get,
};

static int add_new_ctl(struct usb_mixer_interface *mixer,
		       const struct snd_kcontrol_new *ncontrol,
		       usb_mixer_elem_resume_func_t resume,
		       int index, int offset, int num,
		       int val_type, int channels, const char *name,
		       const struct scarlett_mixer_elem_enum_info *opt,
		       struct usb_mixer_elem_info **elem_ret
)
{
	struct snd_kcontrol *kctl;
	struct usb_mixer_elem_info *elem;
	int err;

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

	elem->head.mixer = mixer;
	elem->head.resume = resume;
	elem->control = offset;
	elem->idx_off = num;
	elem->head.id = index;
	elem->val_type = val_type;

	elem->channels = channels;

	/* add scarlett_mixer_elem_enum_info struct */
	elem->private_data = (void *)opt;

	kctl = snd_ctl_new1(ncontrol, elem);
	if (!kctl) {
		kfree(elem);
		return -ENOMEM;
	}
	kctl->private_free = snd_usb_mixer_elem_free;

	strlcpy(kctl->id.name, name, sizeof(kctl->id.name));

	err = snd_usb_mixer_add_control(&elem->head, kctl);
	if (err < 0)
		return err;

	if (elem_ret)
		*elem_ret = elem;

	return 0;
}

static int add_output_ctls(struct usb_mixer_interface *mixer,
			   int index, const char *name,
			   const struct scarlett_device_info *info)
{
	int err;
	char mx[SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
	struct usb_mixer_elem_info *elem;

	/* Add mute switch */
	snprintf(mx, sizeof(mx), "Master %d (%s) Playback Switch",
		index + 1, name);
	err = add_new_ctl(mixer, &usb_scarlett_ctl_switch,
			  scarlett_ctl_resume, 0x0a, 0x01,
			  2*index+1, USB_MIXER_S16, 2, mx, NULL, &elem);
	if (err < 0)
		return err;

	/* Add volume control and initialize to 0 */
	snprintf(mx, sizeof(mx), "Master %d (%s) Playback Volume",
		index + 1, name);
	err = add_new_ctl(mixer, &usb_scarlett_ctl_master,
			  scarlett_ctl_resume, 0x0a, 0x02,
			  2*index+1, USB_MIXER_S16, 2, mx, NULL, &elem);
	if (err < 0)
		return err;

	/* Add L channel source playback enumeration */
	snprintf(mx, sizeof(mx), "Master %dL (%s) Source Playback Enum",
		index + 1, name);
	err = add_new_ctl(mixer, &usb_scarlett_ctl_dynamic_enum,
			  scarlett_ctl_enum_resume, 0x33, 0x00,
			  2*index, USB_MIXER_S16, 1, mx, &info->opt_master,
			  &elem);
	if (err < 0)
		return err;

	/* Add R channel source playback enumeration */
	snprintf(mx, sizeof(mx), "Master %dR (%s) Source Playback Enum",
		index + 1, name);
	err = add_new_ctl(mixer, &usb_scarlett_ctl_dynamic_enum,
			  scarlett_ctl_enum_resume, 0x33, 0x00,
			  2*index+1, USB_MIXER_S16, 1, mx, &info->opt_master,
			  &elem);
	if (err < 0)
		return err;

	return 0;
}

/********************** device-specific config *************************/

/*  untested...  */
static const struct scarlett_device_info s6i6_info = {
	.matrix_in = 18,
	.matrix_out = 8,
	.input_len = 6,
	.output_len = 6,

	.opt_master = {
		.start = -1,
		.len = 27,
		.offsets = {0, 12, 16, 18, 18},
		.names = NULL
	},

	.opt_matrix = {
		.start = -1,
		.len = 19,
		.offsets = {0, 12, 16, 18, 18},
		.names = NULL
	},

	.num_controls = 9,
	.controls = {
		{ .num = 0, .type = SCARLETT_OUTPUTS, .name = "Monitor" },
		{ .num = 1, .type = SCARLETT_OUTPUTS, .name = "Headphone" },
		{ .num = 2, .type = SCARLETT_OUTPUTS, .name = "SPDIF" },
		{ .num = 1, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 1, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 3, .type = SCARLETT_SWITCH_GAIN, .name = NULL},
		{ .num = 4, .type = SCARLETT_SWITCH_GAIN, .name = NULL},
	},

	.matrix_mux_init = {
		12, 13, 14, 15,                 /* Analog -> 1..4 */
		16, 17,                          /* SPDIF -> 5,6 */
		0, 1, 2, 3, 4, 5, 6, 7,     /* PCM[1..12] -> 7..18 */
		8, 9, 10, 11
	}
};

/*  untested...  */
static const struct scarlett_device_info s8i6_info = {
	.matrix_in = 18,
	.matrix_out = 6,
	.input_len = 8,
	.output_len = 6,

	.opt_master = {
		.start = -1,
		.len = 25,
		.offsets = {0, 12, 16, 18, 18},
		.names = NULL
	},

	.opt_matrix = {
		.start = -1,
		.len = 19,
		.offsets = {0, 12, 16, 18, 18},
		.names = NULL
	},

	.num_controls = 7,
	.controls = {
		{ .num = 0, .type = SCARLETT_OUTPUTS, .name = "Monitor" },
		{ .num = 1, .type = SCARLETT_OUTPUTS, .name = "Headphone" },
		{ .num = 2, .type = SCARLETT_OUTPUTS, .name = "SPDIF" },
		{ .num = 1, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 3, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 4, .type = SCARLETT_SWITCH_PAD, .name = NULL},
	},

	.matrix_mux_init = {
		12, 13, 14, 15,                 /* Analog -> 1..4 */
		16, 17,                          /* SPDIF -> 5,6 */
		0, 1, 2, 3, 4, 5, 6, 7,     /* PCM[1..12] -> 7..18 */
		8, 9, 10, 11
	}
};

static const struct scarlett_device_info s18i6_info = {
	.matrix_in = 18,
	.matrix_out = 6,
	.input_len = 18,
	.output_len = 6,

	.opt_master = {
		.start = -1,
		.len = 31,
		.offsets = {0, 6, 14, 16, 24},
		.names = NULL,
	},

	.opt_matrix = {
		.start = -1,
		.len = 25,
		.offsets = {0, 6, 14, 16, 24},
		.names = NULL,
	},

	.num_controls = 5,
	.controls = {
		{ .num = 0, .type = SCARLETT_OUTPUTS, .name = "Monitor" },
		{ .num = 1, .type = SCARLETT_OUTPUTS, .name = "Headphone" },
		{ .num = 2, .type = SCARLETT_OUTPUTS, .name = "SPDIF" },
		{ .num = 1, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
	},

	.matrix_mux_init = {
		 6,  7,  8,  9, 10, 11, 12, 13, /* Analog -> 1..8 */
		16, 17, 18, 19, 20, 21,     /* ADAT[1..6] -> 9..14 */
		14, 15,                          /* SPDIF -> 15,16 */
		0, 1                          /* PCM[1,2] -> 17,18 */
	}
};

static const struct scarlett_device_info s18i8_info = {
	.matrix_in = 18,
	.matrix_out = 8,
	.input_len = 18,
	.output_len = 8,

	.opt_master = {
		.start = -1,
		.len = 35,
		.offsets = {0, 8, 16, 18, 26},
		.names = NULL
	},

	.opt_matrix = {
		.start = -1,
		.len = 27,
		.offsets = {0, 8, 16, 18, 26},
		.names = NULL
	},

	.num_controls = 10,
	.controls = {
		{ .num = 0, .type = SCARLETT_OUTPUTS, .name = "Monitor" },
		{ .num = 1, .type = SCARLETT_OUTPUTS, .name = "Headphone 1" },
		{ .num = 2, .type = SCARLETT_OUTPUTS, .name = "Headphone 2" },
		{ .num = 3, .type = SCARLETT_OUTPUTS, .name = "SPDIF" },
		{ .num = 1, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 1, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 3, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 4, .type = SCARLETT_SWITCH_PAD, .name = NULL},
	},

	.matrix_mux_init = {
		 8,  9, 10, 11, 12, 13, 14, 15, /* Analog -> 1..8 */
		18, 19, 20, 21, 22, 23,     /* ADAT[1..6] -> 9..14 */
		16, 17,                          /* SPDIF -> 15,16 */
		0, 1                          /* PCM[1,2] -> 17,18 */
	}
};

static const struct scarlett_device_info s18i20_info = {
	.matrix_in = 18,
	.matrix_out = 8,
	.input_len = 18,
	.output_len = 20,

	.opt_master = {
		.start = -1,
		.len = 47,
		.offsets = {0, 20, 28, 30, 38},
		.names = NULL
	},

	.opt_matrix = {
		.start = -1,
		.len = 39,
		.offsets = {0, 20, 28, 30, 38},
		.names = NULL
	},

	.num_controls = 10,
	.controls = {
		{ .num = 0, .type = SCARLETT_OUTPUTS, .name = "Monitor" },
		{ .num = 1, .type = SCARLETT_OUTPUTS, .name = "Line 3/4" },
		{ .num = 2, .type = SCARLETT_OUTPUTS, .name = "Line 5/6" },
		{ .num = 3, .type = SCARLETT_OUTPUTS, .name = "Line 7/8" },
		{ .num = 4, .type = SCARLETT_OUTPUTS, .name = "Line 9/10" },
		{ .num = 5, .type = SCARLETT_OUTPUTS, .name = "SPDIF" },
		{ .num = 6, .type = SCARLETT_OUTPUTS, .name = "ADAT 1/2" },
		{ .num = 7, .type = SCARLETT_OUTPUTS, .name = "ADAT 3/4" },
		{ .num = 8, .type = SCARLETT_OUTPUTS, .name = "ADAT 5/6" },
		{ .num = 9, .type = SCARLETT_OUTPUTS, .name = "ADAT 7/8" },
		/*{ .num = 1, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 1, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_IMPEDANCE, .name = NULL},
		{ .num = 2, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 3, .type = SCARLETT_SWITCH_PAD, .name = NULL},
		{ .num = 4, .type = SCARLETT_SWITCH_PAD, .name = NULL},*/
	},

	.matrix_mux_init = {
		20, 21, 22, 23, 24, 25, 26, 27, /* Analog -> 1..8 */
		30, 31, 32, 33, 34, 35,     /* ADAT[1..6] -> 9..14 */
		28, 29,                          /* SPDIF -> 15,16 */
		0, 1                          /* PCM[1,2] -> 17,18 */
	}
};


static int scarlett_controls_create_generic(struct usb_mixer_interface *mixer,
	const struct scarlett_device_info *info)
{
	int i, err;
	char mx[SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
	const struct scarlett_mixer_control *ctl;
	struct usb_mixer_elem_info *elem;

	/* create master switch and playback volume */
	err = add_new_ctl(mixer, &usb_scarlett_ctl_switch,
			  scarlett_ctl_resume, 0x0a, 0x01, 0,
			  USB_MIXER_S16, 1, "Master Playback Switch", NULL,
			  &elem);
	if (err < 0)
		return err;

	err = add_new_ctl(mixer, &usb_scarlett_ctl_master,
			  scarlett_ctl_resume, 0x0a, 0x02, 0,
			  USB_MIXER_S16, 1, "Master Playback Volume", NULL,
			  &elem);
	if (err < 0)
		return err;

	/* iterate through controls in info struct and create each one */
	for (i = 0; i < info->num_controls; i++) {
		ctl = &info->controls[i];

		switch (ctl->type) {
		case SCARLETT_OUTPUTS:
			err = add_output_ctls(mixer, ctl->num, ctl->name, info);
			if (err < 0)
				return err;
			break;
		case SCARLETT_SWITCH_IMPEDANCE:
			sprintf(mx, "Input %d Impedance Switch", ctl->num);
			err = add_new_ctl(mixer, &usb_scarlett_ctl_enum,
					  scarlett_ctl_enum_resume, 0x01,
					  0x09, ctl->num, USB_MIXER_S16, 1, mx,
					  &opt_impedance, &elem);
			if (err < 0)
				return err;
			break;
		case SCARLETT_SWITCH_PAD:
			sprintf(mx, "Input %d Pad Switch", ctl->num);
			err = add_new_ctl(mixer, &usb_scarlett_ctl_enum,
					  scarlett_ctl_enum_resume, 0x01,
					  0x0b, ctl->num, USB_MIXER_S16, 1, mx,
					  &opt_pad, &elem);
			if (err < 0)
				return err;
			break;
		case SCARLETT_SWITCH_GAIN:
			sprintf(mx, "Input %d Gain Switch", ctl->num);
			err = add_new_ctl(mixer, &usb_scarlett_ctl_enum,
					  scarlett_ctl_enum_resume, 0x01,
					  0x08, ctl->num, USB_MIXER_S16, 1, mx,
					  &opt_gain, &elem);
			if (err < 0)
				return err;
			break;
		}
	}

	return 0;
}

/*
 * Create and initialize a mixer for the Focusrite(R) Scarlett
 */
int snd_scarlett_controls_create(struct usb_mixer_interface *mixer)
{
	int err, i, o;
	char mx[SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
	const struct scarlett_device_info *info;
	struct usb_mixer_elem_info *elem;
	static char sample_rate_buffer[4] = { '\x80', '\xbb', '\x00', '\x00' };

	/* only use UAC_VERSION_2 */
	if (!mixer->protocol)
		return 0;

	switch (mixer->chip->usb_id) {
	case USB_ID(0x1235, 0x8012):
		info = &s6i6_info;
		break;
	case USB_ID(0x1235, 0x8002):
		info = &s8i6_info;
		break;
	case USB_ID(0x1235, 0x8004):
		info = &s18i6_info;
		break;
	case USB_ID(0x1235, 0x8014):
		info = &s18i8_info;
		break;
	case USB_ID(0x1235, 0x800c):
		info = &s18i20_info;
		break;
	default: /* device not (yet) supported */
		return -EINVAL;
	}

	/* generic function to create controls */
	err = scarlett_controls_create_generic(mixer, info);
	if (err < 0)
		return err;

	/* setup matrix controls */
	for (i = 0; i < info->matrix_in; i++) {
		snprintf(mx, sizeof(mx), "Matrix %02d Input Playback Route",
			 i+1);
		err = add_new_ctl(mixer, &usb_scarlett_ctl_dynamic_enum,
				  scarlett_ctl_enum_resume, 0x32,
				  0x06, i, USB_MIXER_S16, 1, mx,
				  &info->opt_matrix, &elem);
		if (err < 0)
			return err;

		for (o = 0; o < info->matrix_out; o++) {
			sprintf(mx, "Matrix %02d Mix %c Playback Volume", i+1,
				o+'A');
			err = add_new_ctl(mixer, &usb_scarlett_ctl,
					  scarlett_ctl_resume, 0x3c, 0x00,
					  (i << 3) + (o & 0x07), USB_MIXER_S16,
					  1, mx, NULL, &elem);
			if (err < 0)
				return err;

		}
	}

	for (i = 0; i < info->input_len; i++) {
		snprintf(mx, sizeof(mx), "Input Source %02d Capture Route",
			 i+1);
		err = add_new_ctl(mixer, &usb_scarlett_ctl_dynamic_enum,
				  scarlett_ctl_enum_resume, 0x34,
				  0x00, i, USB_MIXER_S16, 1, mx,
				  &info->opt_master, &elem);
		if (err < 0)
			return err;
	}

	/* val_len == 1 needed here */
	err = add_new_ctl(mixer, &usb_scarlett_ctl_enum,
			  scarlett_ctl_enum_resume, 0x28, 0x01, 0,
			  USB_MIXER_U8, 1, "Sample Clock Source",
			  &opt_clock, &elem);
	if (err < 0)
		return err;

	/* val_len == 1 and UAC2_CS_MEM */
	err = add_new_ctl(mixer, &usb_scarlett_ctl_sync, NULL, 0x3c, 0x00, 2,
			  USB_MIXER_U8, 1, "Sample Clock Sync Status",
			  &opt_sync, &elem);
	if (err < 0)
		return err;

	/* initialize sampling rate to 48000 */
	err = snd_usb_ctl_msg(mixer->chip->dev,
		usb_sndctrlpipe(mixer->chip->dev, 0), UAC2_CS_CUR,
		USB_RECIP_INTERFACE | USB_TYPE_CLASS |
		USB_DIR_OUT, 0x0100, snd_usb_ctrl_intf(mixer->chip) |
		(0x29 << 8), sample_rate_buffer, 4);
	if (err < 0)
		return err;

	return err;
}