aboutsummaryrefslogtreecommitdiffstats
path: root/sound/soc/codecs/cs4270.c
blob: 3920e626494885947853fd856f9d5ed37bc443ed (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
/*
 * CS4270 ALSA SoC (ASoC) codec driver
 *
 * Author: Timur Tabi <timur@freescale.com>
 *
 * Copyright 2007-2009 Freescale Semiconductor, Inc.  This file is licensed
 * under the terms of the GNU General Public License version 2.  This
 * program is licensed "as is" without any warranty of any kind, whether
 * express or implied.
 *
 * This is an ASoC device driver for the Cirrus Logic CS4270 codec.
 *
 * Current features/limitations:
 *
 * - Software mode is supported.  Stand-alone mode is not supported.
 * - Only I2C is supported, not SPI
 * - Support for master and slave mode
 * - The machine driver's 'startup' function must call
 *   cs4270_set_dai_sysclk() with the value of MCLK.
 * - Only I2S and left-justified modes are supported
 * - Power management is supported
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/soc.h>
#include <sound/initval.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/regulator/consumer.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>

/*
 * The codec isn't really big-endian or little-endian, since the I2S
 * interface requires data to be sent serially with the MSbit first.
 * However, to support BE and LE I2S devices, we specify both here.  That
 * way, ALSA will always match the bit patterns.
 */
#define CS4270_FORMATS (SNDRV_PCM_FMTBIT_S8      | \
			SNDRV_PCM_FMTBIT_S16_LE  | SNDRV_PCM_FMTBIT_S16_BE  | \
			SNDRV_PCM_FMTBIT_S18_3LE | SNDRV_PCM_FMTBIT_S18_3BE | \
			SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_S20_3BE | \
			SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE | \
			SNDRV_PCM_FMTBIT_S24_LE  | SNDRV_PCM_FMTBIT_S24_BE)

/* CS4270 registers addresses */
#define CS4270_CHIPID	0x01	/* Chip ID */
#define CS4270_PWRCTL	0x02	/* Power Control */
#define CS4270_MODE	0x03	/* Mode Control */
#define CS4270_FORMAT	0x04	/* Serial Format, ADC/DAC Control */
#define CS4270_TRANS	0x05	/* Transition Control */
#define CS4270_MUTE	0x06	/* Mute Control */
#define CS4270_VOLA	0x07	/* DAC Channel A Volume Control */
#define CS4270_VOLB	0x08	/* DAC Channel B Volume Control */

#define CS4270_FIRSTREG	0x01
#define CS4270_LASTREG	0x08
#define CS4270_NUMREGS	(CS4270_LASTREG - CS4270_FIRSTREG + 1)
#define CS4270_I2C_INCR	0x80

/* Bit masks for the CS4270 registers */
#define CS4270_CHIPID_ID	0xF0
#define CS4270_CHIPID_REV	0x0F
#define CS4270_PWRCTL_FREEZE	0x80
#define CS4270_PWRCTL_PDN_ADC	0x20
#define CS4270_PWRCTL_PDN_DAC	0x02
#define CS4270_PWRCTL_PDN	0x01
#define CS4270_PWRCTL_PDN_ALL	\
	(CS4270_PWRCTL_PDN_ADC | CS4270_PWRCTL_PDN_DAC | CS4270_PWRCTL_PDN)
#define CS4270_MODE_SPEED_MASK	0x30
#define CS4270_MODE_1X		0x00
#define CS4270_MODE_2X		0x10
#define CS4270_MODE_4X		0x20
#define CS4270_MODE_SLAVE	0x30
#define CS4270_MODE_DIV_MASK	0x0E
#define CS4270_MODE_DIV1	0x00
#define CS4270_MODE_DIV15	0x02
#define CS4270_MODE_DIV2	0x04
#define CS4270_MODE_DIV3	0x06
#define CS4270_MODE_DIV4	0x08
#define CS4270_MODE_POPGUARD	0x01
#define CS4270_FORMAT_FREEZE_A	0x80
#define CS4270_FORMAT_FREEZE_B	0x40
#define CS4270_FORMAT_LOOPBACK	0x20
#define CS4270_FORMAT_DAC_MASK	0x18
#define CS4270_FORMAT_DAC_LJ	0x00
#define CS4270_FORMAT_DAC_I2S	0x08
#define CS4270_FORMAT_DAC_RJ16	0x18
#define CS4270_FORMAT_DAC_RJ24	0x10
#define CS4270_FORMAT_ADC_MASK	0x01
#define CS4270_FORMAT_ADC_LJ	0x00
#define CS4270_FORMAT_ADC_I2S	0x01
#define CS4270_TRANS_ONE_VOL	0x80
#define CS4270_TRANS_SOFT	0x40
#define CS4270_TRANS_ZERO	0x20
#define CS4270_TRANS_INV_ADC_A	0x08
#define CS4270_TRANS_INV_ADC_B	0x10
#define CS4270_TRANS_INV_DAC_A	0x02
#define CS4270_TRANS_INV_DAC_B	0x04
#define CS4270_TRANS_DEEMPH	0x01
#define CS4270_MUTE_AUTO	0x20
#define CS4270_MUTE_ADC_A	0x08
#define CS4270_MUTE_ADC_B	0x10
#define CS4270_MUTE_POLARITY	0x04
#define CS4270_MUTE_DAC_A	0x01
#define CS4270_MUTE_DAC_B	0x02

/* Power-on default values for the registers
 *
 * This array contains the power-on default values of the registers, with the
 * exception of the "CHIPID" register (01h).  The lower four bits of that
 * register contain the hardware revision, so it is treated as volatile.
 */
static const struct reg_default cs4270_reg_defaults[] = {
	{ 2, 0x00 },
	{ 3, 0x30 },
	{ 4, 0x00 },
	{ 5, 0x60 },
	{ 6, 0x20 },
	{ 7, 0x00 },
	{ 8, 0x00 },
};

static const char *supply_names[] = {
	"va", "vd", "vlc"
};

/* Private data for the CS4270 */
struct cs4270_private {
	struct regmap *regmap;
	unsigned int mclk; /* Input frequency of the MCLK pin */
	unsigned int mode; /* The mode (I2S or left-justified) */
	unsigned int slave_mode;
	unsigned int manual_mute;

	/* power domain regulators */
	struct regulator_bulk_data supplies[ARRAY_SIZE(supply_names)];
};

static const struct snd_soc_dapm_widget cs4270_dapm_widgets[] = {
SND_SOC_DAPM_INPUT("AINL"),
SND_SOC_DAPM_INPUT("AINR"),

SND_SOC_DAPM_OUTPUT("AOUTL"),
SND_SOC_DAPM_OUTPUT("AOUTR"),
};

static const struct snd_soc_dapm_route cs4270_dapm_routes[] = {
	{ "Capture", NULL, "AINA" },
	{ "Capture", NULL, "AINB" },

	{ "AOUTA", NULL, "Playback" },
	{ "AOUTB", NULL, "Playback" },
};

/**
 * struct cs4270_mode_ratios - clock ratio tables
 * @ratio: the ratio of MCLK to the sample rate
 * @speed_mode: the Speed Mode bits to set in the Mode Control register for
 *              this ratio
 * @mclk: the Ratio Select bits to set in the Mode Control register for this
 *        ratio
 *
 * The data for this chart is taken from Table 5 of the CS4270 reference
 * manual.
 *
 * This table is used to determine how to program the Mode Control register.
 * It is also used by cs4270_set_dai_sysclk() to tell ALSA which sampling
 * rates the CS4270 currently supports.
 *
 * @speed_mode is the corresponding bit pattern to be written to the
 * MODE bits of the Mode Control Register
 *
 * @mclk is the corresponding bit pattern to be wirten to the MCLK bits of
 * the Mode Control Register.
 *
 * In situations where a single ratio is represented by multiple speed
 * modes, we favor the slowest speed.  E.g, for a ratio of 128, we pick
 * double-speed instead of quad-speed.  However, the CS4270 errata states
 * that divide-By-1.5 can cause failures, so we avoid that mode where
 * possible.
 *
 * Errata: There is an errata for the CS4270 where divide-by-1.5 does not
 * work if Vd is 3.3V.  If this effects you, select the
 * CONFIG_SND_SOC_CS4270_VD33_ERRATA Kconfig option, and the driver will
 * never select any sample rates that require divide-by-1.5.
 */
struct cs4270_mode_ratios {
	unsigned int ratio;
	u8 speed_mode;
	u8 mclk;
};

static struct cs4270_mode_ratios cs4270_mode_ratios[] = {
	{64, CS4270_MODE_4X, CS4270_MODE_DIV1},
#ifndef CONFIG_SND_SOC_CS4270_VD33_ERRATA
	{96, CS4270_MODE_4X, CS4270_MODE_DIV15},
#endif
	{128, CS4270_MODE_2X, CS4270_MODE_DIV1},
	{192, CS4270_MODE_4X, CS4270_MODE_DIV3},
	{256, CS4270_MODE_1X, CS4270_MODE_DIV1},
	{384, CS4270_MODE_2X, CS4270_MODE_DIV3},
	{512, CS4270_MODE_1X, CS4270_MODE_DIV2},
	{768, CS4270_MODE_1X, CS4270_MODE_DIV3},
	{1024, CS4270_MODE_1X, CS4270_MODE_DIV4}
};

/* The number of MCLK/LRCK ratios supported by the CS4270 */
#define NUM_MCLK_RATIOS		ARRAY_SIZE(cs4270_mode_ratios)

static bool cs4270_reg_is_readable(struct device *dev, unsigned int reg)
{
	return (reg >= CS4270_FIRSTREG) && (reg <= CS4270_LASTREG);
}

static bool cs4270_reg_is_volatile(struct device *dev, unsigned int reg)
{
	/* Unreadable registers are considered volatile */
	if ((reg < CS4270_FIRSTREG) || (reg > CS4270_LASTREG))
		return 1;

	return reg == CS4270_CHIPID;
}

/**
 * cs4270_set_dai_sysclk - determine the CS4270 samples rates.
 * @codec_dai: the codec DAI
 * @clk_id: the clock ID (ignored)
 * @freq: the MCLK input frequency
 * @dir: the clock direction (ignored)
 *
 * This function is used to tell the codec driver what the input MCLK
 * frequency is.
 *
 * The value of MCLK is used to determine which sample rates are supported
 * by the CS4270.  The ratio of MCLK / Fs must be equal to one of nine
 * supported values - 64, 96, 128, 192, 256, 384, 512, 768, and 1024.
 *
 * This function calculates the nine ratios and determines which ones match
 * a standard sample rate.  If there's a match, then it is added to the list
 * of supported sample rates.
 *
 * This function must be called by the machine driver's 'startup' function,
 * otherwise the list of supported sample rates will not be available in
 * time for ALSA.
 *
 * For setups with variable MCLKs, pass 0 as 'freq' argument. This will cause
 * theoretically possible sample rates to be enabled. Call it again with a
 * proper value set one the external clock is set (most probably you would do
 * that from a machine's driver 'hw_param' hook.
 */
static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
				 int clk_id, unsigned int freq, int dir)
{
	struct snd_soc_codec *codec = codec_dai->codec;
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);

	cs4270->mclk = freq;
	return 0;
}

/**
 * cs4270_set_dai_fmt - configure the codec for the selected audio format
 * @codec_dai: the codec DAI
 * @format: a SND_SOC_DAIFMT_x value indicating the data format
 *
 * This function takes a bitmask of SND_SOC_DAIFMT_x bits and programs the
 * codec accordingly.
 *
 * Currently, this function only supports SND_SOC_DAIFMT_I2S and
 * SND_SOC_DAIFMT_LEFT_J.  The CS4270 codec also supports right-justified
 * data for playback only, but ASoC currently does not support different
 * formats for playback vs. record.
 */
static int cs4270_set_dai_fmt(struct snd_soc_dai *codec_dai,
			      unsigned int format)
{
	struct snd_soc_codec *codec = codec_dai->codec;
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);

	/* set DAI format */
	switch (format & SND_SOC_DAIFMT_FORMAT_MASK) {
	case SND_SOC_DAIFMT_I2S:
	case SND_SOC_DAIFMT_LEFT_J:
		cs4270->mode = format & SND_SOC_DAIFMT_FORMAT_MASK;
		break;
	default:
		dev_err(codec->dev, "invalid dai format\n");
		return -EINVAL;
	}

	/* set master/slave audio interface */
	switch (format & SND_SOC_DAIFMT_MASTER_MASK) {
	case SND_SOC_DAIFMT_CBS_CFS:
		cs4270->slave_mode = 1;
		break;
	case SND_SOC_DAIFMT_CBM_CFM:
		cs4270->slave_mode = 0;
		break;
	default:
		/* all other modes are unsupported by the hardware */
		dev_err(codec->dev, "Unknown master/slave configuration\n");
		return -EINVAL;
	}

	return 0;
}

/**
 * cs4270_hw_params - program the CS4270 with the given hardware parameters.
 * @substream: the audio stream
 * @params: the hardware parameters to set
 * @dai: the SOC DAI (ignored)
 *
 * This function programs the hardware with the values provided.
 * Specifically, the sample rate and the data format.
 *
 * The .ops functions are used to provide board-specific data, like input
 * frequencies, to this driver.  This function takes that information,
 * combines it with the hardware parameters provided, and programs the
 * hardware accordingly.
 */
static int cs4270_hw_params(struct snd_pcm_substream *substream,
			    struct snd_pcm_hw_params *params,
			    struct snd_soc_dai *dai)
{
	struct snd_soc_codec *codec = dai->codec;
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int ret;
	unsigned int i;
	unsigned int rate;
	unsigned int ratio;
	int reg;

	/* Figure out which MCLK/LRCK ratio to use */

	rate = params_rate(params);	/* Sampling rate, in Hz */
	ratio = cs4270->mclk / rate;	/* MCLK/LRCK ratio */

	for (i = 0; i < NUM_MCLK_RATIOS; i++) {
		if (cs4270_mode_ratios[i].ratio == ratio)
			break;
	}

	if (i == NUM_MCLK_RATIOS) {
		/* We did not find a matching ratio */
		dev_err(codec->dev, "could not find matching ratio\n");
		return -EINVAL;
	}

	/* Set the sample rate */

	reg = snd_soc_read(codec, CS4270_MODE);
	reg &= ~(CS4270_MODE_SPEED_MASK | CS4270_MODE_DIV_MASK);
	reg |= cs4270_mode_ratios[i].mclk;

	if (cs4270->slave_mode)
		reg |= CS4270_MODE_SLAVE;
	else
		reg |= cs4270_mode_ratios[i].speed_mode;

	ret = snd_soc_write(codec, CS4270_MODE, reg);
	if (ret < 0) {
		dev_err(codec->dev, "i2c write failed\n");
		return ret;
	}

	/* Set the DAI format */

	reg = snd_soc_read(codec, CS4270_FORMAT);
	reg &= ~(CS4270_FORMAT_DAC_MASK | CS4270_FORMAT_ADC_MASK);

	switch (cs4270->mode) {
	case SND_SOC_DAIFMT_I2S:
		reg |= CS4270_FORMAT_DAC_I2S | CS4270_FORMAT_ADC_I2S;
		break;
	case SND_SOC_DAIFMT_LEFT_J:
		reg |= CS4270_FORMAT_DAC_LJ | CS4270_FORMAT_ADC_LJ;
		break;
	default:
		dev_err(codec->dev, "unknown dai format\n");
		return -EINVAL;
	}

	ret = snd_soc_write(codec, CS4270_FORMAT, reg);
	if (ret < 0) {
		dev_err(codec->dev, "i2c write failed\n");
		return ret;
	}

	return ret;
}

/**
 * cs4270_dai_mute - enable/disable the CS4270 external mute
 * @dai: the SOC DAI
 * @mute: 0 = disable mute, 1 = enable mute
 *
 * This function toggles the mute bits in the MUTE register.  The CS4270's
 * mute capability is intended for external muting circuitry, so if the
 * board does not have the MUTEA or MUTEB pins connected to such circuitry,
 * then this function will do nothing.
 */
static int cs4270_dai_mute(struct snd_soc_dai *dai, int mute)
{
	struct snd_soc_codec *codec = dai->codec;
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int reg6;

	reg6 = snd_soc_read(codec, CS4270_MUTE);

	if (mute)
		reg6 |= CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B;
	else {
		reg6 &= ~(CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B);
		reg6 |= cs4270->manual_mute;
	}

	return snd_soc_write(codec, CS4270_MUTE, reg6);
}

/**
 * cs4270_soc_put_mute - put callback for the 'Master Playback switch'
 * 			 alsa control.
 * @kcontrol: mixer control
 * @ucontrol: control element information
 *
 * This function basically passes the arguments on to the generic
 * snd_soc_put_volsw() function and saves the mute information in
 * our private data structure. This is because we want to prevent
 * cs4270_dai_mute() neglecting the user's decision to manually
 * mute the codec's output.
 *
 * Returns 0 for success.
 */
static int cs4270_soc_put_mute(struct snd_kcontrol *kcontrol,
				struct snd_ctl_elem_value *ucontrol)
{
	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int left = !ucontrol->value.integer.value[0];
	int right = !ucontrol->value.integer.value[1];

	cs4270->manual_mute = (left ? CS4270_MUTE_DAC_A : 0) |
			      (right ? CS4270_MUTE_DAC_B : 0);

	return snd_soc_put_volsw(kcontrol, ucontrol);
}

/* A list of non-DAPM controls that the CS4270 supports */
static const struct snd_kcontrol_new cs4270_snd_controls[] = {
	SOC_DOUBLE_R("Master Playback Volume",
		CS4270_VOLA, CS4270_VOLB, 0, 0xFF, 1),
	SOC_SINGLE("Digital Sidetone Switch", CS4270_FORMAT, 5, 1, 0),
	SOC_SINGLE("Soft Ramp Switch", CS4270_TRANS, 6, 1, 0),
	SOC_SINGLE("Zero Cross Switch", CS4270_TRANS, 5, 1, 0),
	SOC_SINGLE("De-emphasis filter", CS4270_TRANS, 0, 1, 0),
	SOC_SINGLE("Popguard Switch", CS4270_MODE, 0, 1, 1),
	SOC_SINGLE("Auto-Mute Switch", CS4270_MUTE, 5, 1, 0),
	SOC_DOUBLE("Master Capture Switch", CS4270_MUTE, 3, 4, 1, 1),
	SOC_DOUBLE_EXT("Master Playback Switch", CS4270_MUTE, 0, 1, 1, 1,
		snd_soc_get_volsw, cs4270_soc_put_mute),
};

static const struct snd_soc_dai_ops cs4270_dai_ops = {
	.hw_params	= cs4270_hw_params,
	.set_sysclk	= cs4270_set_dai_sysclk,
	.set_fmt	= cs4270_set_dai_fmt,
	.digital_mute	= cs4270_dai_mute,
};

static struct snd_soc_dai_driver cs4270_dai = {
	.name = "cs4270-hifi",
	.playback = {
		.stream_name = "Playback",
		.channels_min = 2,
		.channels_max = 2,
		.rates = SNDRV_PCM_RATE_CONTINUOUS,
		.rate_min = 4000,
		.rate_max = 216000,
		.formats = CS4270_FORMATS,
	},
	.capture = {
		.stream_name = "Capture",
		.channels_min = 2,
		.channels_max = 2,
		.rates = SNDRV_PCM_RATE_CONTINUOUS,
		.rate_min = 4000,
		.rate_max = 216000,
		.formats = CS4270_FORMATS,
	},
	.ops = &cs4270_dai_ops,
};

/**
 * cs4270_probe - ASoC probe function
 * @pdev: platform device
 *
 * This function is called when ASoC has all the pieces it needs to
 * instantiate a sound driver.
 */
static int cs4270_probe(struct snd_soc_codec *codec)
{
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int ret;

	/* Disable auto-mute.  This feature appears to be buggy.  In some
	 * situations, auto-mute will not deactivate when it should, so we want
	 * this feature disabled by default.  An application (e.g. alsactl) can
	 * re-enabled it by using the controls.
	 */
	ret = snd_soc_update_bits(codec, CS4270_MUTE, CS4270_MUTE_AUTO, 0);
	if (ret < 0) {
		dev_err(codec->dev, "i2c write failed\n");
		return ret;
	}

	/* Disable automatic volume control.  The hardware enables, and it
	 * causes volume change commands to be delayed, sometimes until after
	 * playback has started.  An application (e.g. alsactl) can
	 * re-enabled it by using the controls.
	 */
	ret = snd_soc_update_bits(codec, CS4270_TRANS,
		CS4270_TRANS_SOFT | CS4270_TRANS_ZERO, 0);
	if (ret < 0) {
		dev_err(codec->dev, "i2c write failed\n");
		return ret;
	}

	ret = regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
				    cs4270->supplies);

	return ret;
}

/**
 * cs4270_remove - ASoC remove function
 * @pdev: platform device
 *
 * This function is the counterpart to cs4270_probe().
 */
static int cs4270_remove(struct snd_soc_codec *codec)
{
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);

	regulator_bulk_disable(ARRAY_SIZE(cs4270->supplies), cs4270->supplies);

	return 0;
};

#ifdef CONFIG_PM

/* This suspend/resume implementation can handle both - a simple standby
 * where the codec remains powered, and a full suspend, where the voltage
 * domain the codec is connected to is teared down and/or any other hardware
 * reset condition is asserted.
 *
 * The codec's own power saving features are enabled in the suspend callback,
 * and all registers are written back to the hardware when resuming.
 */

static int cs4270_soc_suspend(struct snd_soc_codec *codec)
{
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int reg, ret;

	reg = snd_soc_read(codec, CS4270_PWRCTL) | CS4270_PWRCTL_PDN_ALL;
	if (reg < 0)
		return reg;

	ret = snd_soc_write(codec, CS4270_PWRCTL, reg);
	if (ret < 0)
		return ret;

	regulator_bulk_disable(ARRAY_SIZE(cs4270->supplies),
			       cs4270->supplies);

	return 0;
}

static int cs4270_soc_resume(struct snd_soc_codec *codec)
{
	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
	int reg, ret;

	ret = regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
				    cs4270->supplies);
	if (ret != 0)
		return ret;

	/* In case the device was put to hard reset during sleep, we need to
	 * wait 500ns here before any I2C communication. */
	ndelay(500);

	/* first restore the entire register cache ... */
	regcache_sync(cs4270->regmap);

	/* ... then disable the power-down bits */
	reg = snd_soc_read(codec, CS4270_PWRCTL);
	reg &= ~CS4270_PWRCTL_PDN_ALL;

	return snd_soc_write(codec, CS4270_PWRCTL, reg);
}
#else
#define cs4270_soc_suspend	NULL
#define cs4270_soc_resume	NULL
#endif /* CONFIG_PM */

/*
 * ASoC codec driver structure
 */
static const struct snd_soc_codec_driver soc_codec_device_cs4270 = {
	.probe =		cs4270_probe,
	.remove =		cs4270_remove,
	.suspend =		cs4270_soc_suspend,
	.resume =		cs4270_soc_resume,

	.controls =		cs4270_snd_controls,
	.num_controls =		ARRAY_SIZE(cs4270_snd_controls),
	.dapm_widgets =		cs4270_dapm_widgets,
	.num_dapm_widgets =	ARRAY_SIZE(cs4270_dapm_widgets),
	.dapm_routes =		cs4270_dapm_routes,
	.num_dapm_routes =	ARRAY_SIZE(cs4270_dapm_routes),
};

/*
 * cs4270_of_match - the device tree bindings
 */
static const struct of_device_id cs4270_of_match[] = {
	{ .compatible = "cirrus,cs4270", },
	{ }
};
MODULE_DEVICE_TABLE(of, cs4270_of_match);

static const struct regmap_config cs4270_regmap = {
	.reg_bits =		8,
	.val_bits =		8,
	.max_register =		CS4270_LASTREG,
	.reg_defaults =		cs4270_reg_defaults,
	.num_reg_defaults =	ARRAY_SIZE(cs4270_reg_defaults),
	.cache_type =		REGCACHE_RBTREE,

	.readable_reg =		cs4270_reg_is_readable,
	.volatile_reg =		cs4270_reg_is_volatile,
};

/**
 * cs4270_i2c_probe - initialize the I2C interface of the CS4270
 * @i2c_client: the I2C client object
 * @id: the I2C device ID (ignored)
 *
 * This function is called whenever the I2C subsystem finds a device that
 * matches the device ID given via a prior call to i2c_add_driver().
 */
static int cs4270_i2c_probe(struct i2c_client *i2c_client,
	const struct i2c_device_id *id)
{
	struct device_node *np = i2c_client->dev.of_node;
	struct cs4270_private *cs4270;
	unsigned int val;
	int ret, i;

	cs4270 = devm_kzalloc(&i2c_client->dev, sizeof(struct cs4270_private),
			      GFP_KERNEL);
	if (!cs4270) {
		dev_err(&i2c_client->dev, "could not allocate codec\n");
		return -ENOMEM;
	}

	/* get the power supply regulators */
	for (i = 0; i < ARRAY_SIZE(supply_names); i++)
		cs4270->supplies[i].supply = supply_names[i];

	ret = devm_regulator_bulk_get(&i2c_client->dev,
				      ARRAY_SIZE(cs4270->supplies),
				      cs4270->supplies);
	if (ret < 0)
		return ret;

	/* See if we have a way to bring the codec out of reset */
	if (np) {
		enum of_gpio_flags flags;
		int gpio = of_get_named_gpio_flags(np, "reset-gpio", 0, &flags);

		if (gpio_is_valid(gpio)) {
			ret = devm_gpio_request_one(&i2c_client->dev, gpio,
				     flags & OF_GPIO_ACTIVE_LOW ?
					GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH,
				     "cs4270 reset");
			if (ret < 0)
				return ret;
		}
	}

	cs4270->regmap = devm_regmap_init_i2c(i2c_client, &cs4270_regmap);
	if (IS_ERR(cs4270->regmap))
		return PTR_ERR(cs4270->regmap);

	/* Verify that we have a CS4270 */
	ret = regmap_read(cs4270->regmap, CS4270_CHIPID, &val);
	if (ret < 0) {
		dev_err(&i2c_client->dev, "failed to read i2c at addr %X\n",
		       i2c_client->addr);
		return ret;
	}
	/* The top four bits of the chip ID should be 1100. */
	if ((val & 0xF0) != 0xC0) {
		dev_err(&i2c_client->dev, "device at addr %X is not a CS4270\n",
		       i2c_client->addr);
		return -ENODEV;
	}

	dev_info(&i2c_client->dev, "found device at i2c address %X\n",
		i2c_client->addr);
	dev_info(&i2c_client->dev, "hardware revision %X\n", val & 0xF);

	i2c_set_clientdata(i2c_client, cs4270);

	ret = snd_soc_register_codec(&i2c_client->dev,
			&soc_codec_device_cs4270, &cs4270_dai, 1);
	return ret;
}

/**
 * cs4270_i2c_remove - remove an I2C device
 * @i2c_client: the I2C client object
 *
 * This function is the counterpart to cs4270_i2c_probe().
 */
static int cs4270_i2c_remove(struct i2c_client *i2c_client)
{
	snd_soc_unregister_codec(&i2c_client->dev);
	return 0;
}

/*
 * cs4270_id - I2C device IDs supported by this driver
 */
static const struct i2c_device_id cs4270_id[] = {
	{"cs4270", 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, cs4270_id);

/*
 * cs4270_i2c_driver - I2C device identification
 *
 * This structure tells the I2C subsystem how to identify and support a
 * given I2C device type.
 */
static struct i2c_driver cs4270_i2c_driver = {
	.driver = {
		.name = "cs4270",
		.owner = THIS_MODULE,
		.of_match_table = cs4270_of_match,
	},
	.id_table = cs4270_id,
	.probe = cs4270_i2c_probe,
	.remove = cs4270_i2c_remove,
};

module_i2c_driver(cs4270_i2c_driver);

MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
MODULE_DESCRIPTION("Cirrus Logic CS4270 ALSA SoC Codec Driver");
MODULE_LICENSE("GPL");