xref: /openbmc/linux/sound/soc/codecs/cs4270.c (revision f7777dcc)
1 /*
2  * CS4270 ALSA SoC (ASoC) codec driver
3  *
4  * Author: Timur Tabi <timur@freescale.com>
5  *
6  * Copyright 2007-2009 Freescale Semiconductor, Inc.  This file is licensed
7  * under the terms of the GNU General Public License version 2.  This
8  * program is licensed "as is" without any warranty of any kind, whether
9  * express or implied.
10  *
11  * This is an ASoC device driver for the Cirrus Logic CS4270 codec.
12  *
13  * Current features/limitations:
14  *
15  * - Software mode is supported.  Stand-alone mode is not supported.
16  * - Only I2C is supported, not SPI
17  * - Support for master and slave mode
18  * - The machine driver's 'startup' function must call
19  *   cs4270_set_dai_sysclk() with the value of MCLK.
20  * - Only I2S and left-justified modes are supported
21  * - Power management is supported
22  */
23 
24 #include <linux/module.h>
25 #include <linux/slab.h>
26 #include <sound/core.h>
27 #include <sound/soc.h>
28 #include <sound/initval.h>
29 #include <linux/i2c.h>
30 #include <linux/delay.h>
31 #include <linux/regulator/consumer.h>
32 #include <linux/of_device.h>
33 #include <linux/of_gpio.h>
34 
35 /*
36  * The codec isn't really big-endian or little-endian, since the I2S
37  * interface requires data to be sent serially with the MSbit first.
38  * However, to support BE and LE I2S devices, we specify both here.  That
39  * way, ALSA will always match the bit patterns.
40  */
41 #define CS4270_FORMATS (SNDRV_PCM_FMTBIT_S8      | \
42 			SNDRV_PCM_FMTBIT_S16_LE  | SNDRV_PCM_FMTBIT_S16_BE  | \
43 			SNDRV_PCM_FMTBIT_S18_3LE | SNDRV_PCM_FMTBIT_S18_3BE | \
44 			SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_S20_3BE | \
45 			SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE | \
46 			SNDRV_PCM_FMTBIT_S24_LE  | SNDRV_PCM_FMTBIT_S24_BE)
47 
48 /* CS4270 registers addresses */
49 #define CS4270_CHIPID	0x01	/* Chip ID */
50 #define CS4270_PWRCTL	0x02	/* Power Control */
51 #define CS4270_MODE	0x03	/* Mode Control */
52 #define CS4270_FORMAT	0x04	/* Serial Format, ADC/DAC Control */
53 #define CS4270_TRANS	0x05	/* Transition Control */
54 #define CS4270_MUTE	0x06	/* Mute Control */
55 #define CS4270_VOLA	0x07	/* DAC Channel A Volume Control */
56 #define CS4270_VOLB	0x08	/* DAC Channel B Volume Control */
57 
58 #define CS4270_FIRSTREG	0x01
59 #define CS4270_LASTREG	0x08
60 #define CS4270_NUMREGS	(CS4270_LASTREG - CS4270_FIRSTREG + 1)
61 #define CS4270_I2C_INCR	0x80
62 
63 /* Bit masks for the CS4270 registers */
64 #define CS4270_CHIPID_ID	0xF0
65 #define CS4270_CHIPID_REV	0x0F
66 #define CS4270_PWRCTL_FREEZE	0x80
67 #define CS4270_PWRCTL_PDN_ADC	0x20
68 #define CS4270_PWRCTL_PDN_DAC	0x02
69 #define CS4270_PWRCTL_PDN	0x01
70 #define CS4270_PWRCTL_PDN_ALL	\
71 	(CS4270_PWRCTL_PDN_ADC | CS4270_PWRCTL_PDN_DAC | CS4270_PWRCTL_PDN)
72 #define CS4270_MODE_SPEED_MASK	0x30
73 #define CS4270_MODE_1X		0x00
74 #define CS4270_MODE_2X		0x10
75 #define CS4270_MODE_4X		0x20
76 #define CS4270_MODE_SLAVE	0x30
77 #define CS4270_MODE_DIV_MASK	0x0E
78 #define CS4270_MODE_DIV1	0x00
79 #define CS4270_MODE_DIV15	0x02
80 #define CS4270_MODE_DIV2	0x04
81 #define CS4270_MODE_DIV3	0x06
82 #define CS4270_MODE_DIV4	0x08
83 #define CS4270_MODE_POPGUARD	0x01
84 #define CS4270_FORMAT_FREEZE_A	0x80
85 #define CS4270_FORMAT_FREEZE_B	0x40
86 #define CS4270_FORMAT_LOOPBACK	0x20
87 #define CS4270_FORMAT_DAC_MASK	0x18
88 #define CS4270_FORMAT_DAC_LJ	0x00
89 #define CS4270_FORMAT_DAC_I2S	0x08
90 #define CS4270_FORMAT_DAC_RJ16	0x18
91 #define CS4270_FORMAT_DAC_RJ24	0x10
92 #define CS4270_FORMAT_ADC_MASK	0x01
93 #define CS4270_FORMAT_ADC_LJ	0x00
94 #define CS4270_FORMAT_ADC_I2S	0x01
95 #define CS4270_TRANS_ONE_VOL	0x80
96 #define CS4270_TRANS_SOFT	0x40
97 #define CS4270_TRANS_ZERO	0x20
98 #define CS4270_TRANS_INV_ADC_A	0x08
99 #define CS4270_TRANS_INV_ADC_B	0x10
100 #define CS4270_TRANS_INV_DAC_A	0x02
101 #define CS4270_TRANS_INV_DAC_B	0x04
102 #define CS4270_TRANS_DEEMPH	0x01
103 #define CS4270_MUTE_AUTO	0x20
104 #define CS4270_MUTE_ADC_A	0x08
105 #define CS4270_MUTE_ADC_B	0x10
106 #define CS4270_MUTE_POLARITY	0x04
107 #define CS4270_MUTE_DAC_A	0x01
108 #define CS4270_MUTE_DAC_B	0x02
109 
110 /* Power-on default values for the registers
111  *
112  * This array contains the power-on default values of the registers, with the
113  * exception of the "CHIPID" register (01h).  The lower four bits of that
114  * register contain the hardware revision, so it is treated as volatile.
115  */
116 static const struct reg_default cs4270_reg_defaults[] = {
117 	{ 2, 0x00 },
118 	{ 3, 0x30 },
119 	{ 4, 0x00 },
120 	{ 5, 0x60 },
121 	{ 6, 0x20 },
122 	{ 7, 0x00 },
123 	{ 8, 0x00 },
124 };
125 
126 static const char *supply_names[] = {
127 	"va", "vd", "vlc"
128 };
129 
130 /* Private data for the CS4270 */
131 struct cs4270_private {
132 	struct regmap *regmap;
133 	unsigned int mclk; /* Input frequency of the MCLK pin */
134 	unsigned int mode; /* The mode (I2S or left-justified) */
135 	unsigned int slave_mode;
136 	unsigned int manual_mute;
137 
138 	/* power domain regulators */
139 	struct regulator_bulk_data supplies[ARRAY_SIZE(supply_names)];
140 };
141 
142 static const struct snd_soc_dapm_widget cs4270_dapm_widgets[] = {
143 SND_SOC_DAPM_INPUT("AINL"),
144 SND_SOC_DAPM_INPUT("AINR"),
145 
146 SND_SOC_DAPM_OUTPUT("AOUTL"),
147 SND_SOC_DAPM_OUTPUT("AOUTR"),
148 };
149 
150 static const struct snd_soc_dapm_route cs4270_dapm_routes[] = {
151 	{ "Capture", NULL, "AINA" },
152 	{ "Capture", NULL, "AINB" },
153 
154 	{ "AOUTA", NULL, "Playback" },
155 	{ "AOUTB", NULL, "Playback" },
156 };
157 
158 /**
159  * struct cs4270_mode_ratios - clock ratio tables
160  * @ratio: the ratio of MCLK to the sample rate
161  * @speed_mode: the Speed Mode bits to set in the Mode Control register for
162  *              this ratio
163  * @mclk: the Ratio Select bits to set in the Mode Control register for this
164  *        ratio
165  *
166  * The data for this chart is taken from Table 5 of the CS4270 reference
167  * manual.
168  *
169  * This table is used to determine how to program the Mode Control register.
170  * It is also used by cs4270_set_dai_sysclk() to tell ALSA which sampling
171  * rates the CS4270 currently supports.
172  *
173  * @speed_mode is the corresponding bit pattern to be written to the
174  * MODE bits of the Mode Control Register
175  *
176  * @mclk is the corresponding bit pattern to be wirten to the MCLK bits of
177  * the Mode Control Register.
178  *
179  * In situations where a single ratio is represented by multiple speed
180  * modes, we favor the slowest speed.  E.g, for a ratio of 128, we pick
181  * double-speed instead of quad-speed.  However, the CS4270 errata states
182  * that divide-By-1.5 can cause failures, so we avoid that mode where
183  * possible.
184  *
185  * Errata: There is an errata for the CS4270 where divide-by-1.5 does not
186  * work if Vd is 3.3V.  If this effects you, select the
187  * CONFIG_SND_SOC_CS4270_VD33_ERRATA Kconfig option, and the driver will
188  * never select any sample rates that require divide-by-1.5.
189  */
190 struct cs4270_mode_ratios {
191 	unsigned int ratio;
192 	u8 speed_mode;
193 	u8 mclk;
194 };
195 
196 static struct cs4270_mode_ratios cs4270_mode_ratios[] = {
197 	{64, CS4270_MODE_4X, CS4270_MODE_DIV1},
198 #ifndef CONFIG_SND_SOC_CS4270_VD33_ERRATA
199 	{96, CS4270_MODE_4X, CS4270_MODE_DIV15},
200 #endif
201 	{128, CS4270_MODE_2X, CS4270_MODE_DIV1},
202 	{192, CS4270_MODE_4X, CS4270_MODE_DIV3},
203 	{256, CS4270_MODE_1X, CS4270_MODE_DIV1},
204 	{384, CS4270_MODE_2X, CS4270_MODE_DIV3},
205 	{512, CS4270_MODE_1X, CS4270_MODE_DIV2},
206 	{768, CS4270_MODE_1X, CS4270_MODE_DIV3},
207 	{1024, CS4270_MODE_1X, CS4270_MODE_DIV4}
208 };
209 
210 /* The number of MCLK/LRCK ratios supported by the CS4270 */
211 #define NUM_MCLK_RATIOS		ARRAY_SIZE(cs4270_mode_ratios)
212 
213 static bool cs4270_reg_is_readable(struct device *dev, unsigned int reg)
214 {
215 	return (reg >= CS4270_FIRSTREG) && (reg <= CS4270_LASTREG);
216 }
217 
218 static bool cs4270_reg_is_volatile(struct device *dev, unsigned int reg)
219 {
220 	/* Unreadable registers are considered volatile */
221 	if ((reg < CS4270_FIRSTREG) || (reg > CS4270_LASTREG))
222 		return 1;
223 
224 	return reg == CS4270_CHIPID;
225 }
226 
227 /**
228  * cs4270_set_dai_sysclk - determine the CS4270 samples rates.
229  * @codec_dai: the codec DAI
230  * @clk_id: the clock ID (ignored)
231  * @freq: the MCLK input frequency
232  * @dir: the clock direction (ignored)
233  *
234  * This function is used to tell the codec driver what the input MCLK
235  * frequency is.
236  *
237  * The value of MCLK is used to determine which sample rates are supported
238  * by the CS4270.  The ratio of MCLK / Fs must be equal to one of nine
239  * supported values - 64, 96, 128, 192, 256, 384, 512, 768, and 1024.
240  *
241  * This function calculates the nine ratios and determines which ones match
242  * a standard sample rate.  If there's a match, then it is added to the list
243  * of supported sample rates.
244  *
245  * This function must be called by the machine driver's 'startup' function,
246  * otherwise the list of supported sample rates will not be available in
247  * time for ALSA.
248  *
249  * For setups with variable MCLKs, pass 0 as 'freq' argument. This will cause
250  * theoretically possible sample rates to be enabled. Call it again with a
251  * proper value set one the external clock is set (most probably you would do
252  * that from a machine's driver 'hw_param' hook.
253  */
254 static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
255 				 int clk_id, unsigned int freq, int dir)
256 {
257 	struct snd_soc_codec *codec = codec_dai->codec;
258 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
259 
260 	cs4270->mclk = freq;
261 	return 0;
262 }
263 
264 /**
265  * cs4270_set_dai_fmt - configure the codec for the selected audio format
266  * @codec_dai: the codec DAI
267  * @format: a SND_SOC_DAIFMT_x value indicating the data format
268  *
269  * This function takes a bitmask of SND_SOC_DAIFMT_x bits and programs the
270  * codec accordingly.
271  *
272  * Currently, this function only supports SND_SOC_DAIFMT_I2S and
273  * SND_SOC_DAIFMT_LEFT_J.  The CS4270 codec also supports right-justified
274  * data for playback only, but ASoC currently does not support different
275  * formats for playback vs. record.
276  */
277 static int cs4270_set_dai_fmt(struct snd_soc_dai *codec_dai,
278 			      unsigned int format)
279 {
280 	struct snd_soc_codec *codec = codec_dai->codec;
281 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
282 
283 	/* set DAI format */
284 	switch (format & SND_SOC_DAIFMT_FORMAT_MASK) {
285 	case SND_SOC_DAIFMT_I2S:
286 	case SND_SOC_DAIFMT_LEFT_J:
287 		cs4270->mode = format & SND_SOC_DAIFMT_FORMAT_MASK;
288 		break;
289 	default:
290 		dev_err(codec->dev, "invalid dai format\n");
291 		return -EINVAL;
292 	}
293 
294 	/* set master/slave audio interface */
295 	switch (format & SND_SOC_DAIFMT_MASTER_MASK) {
296 	case SND_SOC_DAIFMT_CBS_CFS:
297 		cs4270->slave_mode = 1;
298 		break;
299 	case SND_SOC_DAIFMT_CBM_CFM:
300 		cs4270->slave_mode = 0;
301 		break;
302 	default:
303 		/* all other modes are unsupported by the hardware */
304 		dev_err(codec->dev, "Unknown master/slave configuration\n");
305 		return -EINVAL;
306 	}
307 
308 	return 0;
309 }
310 
311 /**
312  * cs4270_hw_params - program the CS4270 with the given hardware parameters.
313  * @substream: the audio stream
314  * @params: the hardware parameters to set
315  * @dai: the SOC DAI (ignored)
316  *
317  * This function programs the hardware with the values provided.
318  * Specifically, the sample rate and the data format.
319  *
320  * The .ops functions are used to provide board-specific data, like input
321  * frequencies, to this driver.  This function takes that information,
322  * combines it with the hardware parameters provided, and programs the
323  * hardware accordingly.
324  */
325 static int cs4270_hw_params(struct snd_pcm_substream *substream,
326 			    struct snd_pcm_hw_params *params,
327 			    struct snd_soc_dai *dai)
328 {
329 	struct snd_soc_codec *codec = dai->codec;
330 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
331 	int ret;
332 	unsigned int i;
333 	unsigned int rate;
334 	unsigned int ratio;
335 	int reg;
336 
337 	/* Figure out which MCLK/LRCK ratio to use */
338 
339 	rate = params_rate(params);	/* Sampling rate, in Hz */
340 	ratio = cs4270->mclk / rate;	/* MCLK/LRCK ratio */
341 
342 	for (i = 0; i < NUM_MCLK_RATIOS; i++) {
343 		if (cs4270_mode_ratios[i].ratio == ratio)
344 			break;
345 	}
346 
347 	if (i == NUM_MCLK_RATIOS) {
348 		/* We did not find a matching ratio */
349 		dev_err(codec->dev, "could not find matching ratio\n");
350 		return -EINVAL;
351 	}
352 
353 	/* Set the sample rate */
354 
355 	reg = snd_soc_read(codec, CS4270_MODE);
356 	reg &= ~(CS4270_MODE_SPEED_MASK | CS4270_MODE_DIV_MASK);
357 	reg |= cs4270_mode_ratios[i].mclk;
358 
359 	if (cs4270->slave_mode)
360 		reg |= CS4270_MODE_SLAVE;
361 	else
362 		reg |= cs4270_mode_ratios[i].speed_mode;
363 
364 	ret = snd_soc_write(codec, CS4270_MODE, reg);
365 	if (ret < 0) {
366 		dev_err(codec->dev, "i2c write failed\n");
367 		return ret;
368 	}
369 
370 	/* Set the DAI format */
371 
372 	reg = snd_soc_read(codec, CS4270_FORMAT);
373 	reg &= ~(CS4270_FORMAT_DAC_MASK | CS4270_FORMAT_ADC_MASK);
374 
375 	switch (cs4270->mode) {
376 	case SND_SOC_DAIFMT_I2S:
377 		reg |= CS4270_FORMAT_DAC_I2S | CS4270_FORMAT_ADC_I2S;
378 		break;
379 	case SND_SOC_DAIFMT_LEFT_J:
380 		reg |= CS4270_FORMAT_DAC_LJ | CS4270_FORMAT_ADC_LJ;
381 		break;
382 	default:
383 		dev_err(codec->dev, "unknown dai format\n");
384 		return -EINVAL;
385 	}
386 
387 	ret = snd_soc_write(codec, CS4270_FORMAT, reg);
388 	if (ret < 0) {
389 		dev_err(codec->dev, "i2c write failed\n");
390 		return ret;
391 	}
392 
393 	return ret;
394 }
395 
396 /**
397  * cs4270_dai_mute - enable/disable the CS4270 external mute
398  * @dai: the SOC DAI
399  * @mute: 0 = disable mute, 1 = enable mute
400  *
401  * This function toggles the mute bits in the MUTE register.  The CS4270's
402  * mute capability is intended for external muting circuitry, so if the
403  * board does not have the MUTEA or MUTEB pins connected to such circuitry,
404  * then this function will do nothing.
405  */
406 static int cs4270_dai_mute(struct snd_soc_dai *dai, int mute)
407 {
408 	struct snd_soc_codec *codec = dai->codec;
409 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
410 	int reg6;
411 
412 	reg6 = snd_soc_read(codec, CS4270_MUTE);
413 
414 	if (mute)
415 		reg6 |= CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B;
416 	else {
417 		reg6 &= ~(CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B);
418 		reg6 |= cs4270->manual_mute;
419 	}
420 
421 	return snd_soc_write(codec, CS4270_MUTE, reg6);
422 }
423 
424 /**
425  * cs4270_soc_put_mute - put callback for the 'Master Playback switch'
426  * 			 alsa control.
427  * @kcontrol: mixer control
428  * @ucontrol: control element information
429  *
430  * This function basically passes the arguments on to the generic
431  * snd_soc_put_volsw() function and saves the mute information in
432  * our private data structure. This is because we want to prevent
433  * cs4270_dai_mute() neglecting the user's decision to manually
434  * mute the codec's output.
435  *
436  * Returns 0 for success.
437  */
438 static int cs4270_soc_put_mute(struct snd_kcontrol *kcontrol,
439 				struct snd_ctl_elem_value *ucontrol)
440 {
441 	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
442 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
443 	int left = !ucontrol->value.integer.value[0];
444 	int right = !ucontrol->value.integer.value[1];
445 
446 	cs4270->manual_mute = (left ? CS4270_MUTE_DAC_A : 0) |
447 			      (right ? CS4270_MUTE_DAC_B : 0);
448 
449 	return snd_soc_put_volsw(kcontrol, ucontrol);
450 }
451 
452 /* A list of non-DAPM controls that the CS4270 supports */
453 static const struct snd_kcontrol_new cs4270_snd_controls[] = {
454 	SOC_DOUBLE_R("Master Playback Volume",
455 		CS4270_VOLA, CS4270_VOLB, 0, 0xFF, 1),
456 	SOC_SINGLE("Digital Sidetone Switch", CS4270_FORMAT, 5, 1, 0),
457 	SOC_SINGLE("Soft Ramp Switch", CS4270_TRANS, 6, 1, 0),
458 	SOC_SINGLE("Zero Cross Switch", CS4270_TRANS, 5, 1, 0),
459 	SOC_SINGLE("De-emphasis filter", CS4270_TRANS, 0, 1, 0),
460 	SOC_SINGLE("Popguard Switch", CS4270_MODE, 0, 1, 1),
461 	SOC_SINGLE("Auto-Mute Switch", CS4270_MUTE, 5, 1, 0),
462 	SOC_DOUBLE("Master Capture Switch", CS4270_MUTE, 3, 4, 1, 1),
463 	SOC_DOUBLE_EXT("Master Playback Switch", CS4270_MUTE, 0, 1, 1, 1,
464 		snd_soc_get_volsw, cs4270_soc_put_mute),
465 };
466 
467 static const struct snd_soc_dai_ops cs4270_dai_ops = {
468 	.hw_params	= cs4270_hw_params,
469 	.set_sysclk	= cs4270_set_dai_sysclk,
470 	.set_fmt	= cs4270_set_dai_fmt,
471 	.digital_mute	= cs4270_dai_mute,
472 };
473 
474 static struct snd_soc_dai_driver cs4270_dai = {
475 	.name = "cs4270-hifi",
476 	.playback = {
477 		.stream_name = "Playback",
478 		.channels_min = 2,
479 		.channels_max = 2,
480 		.rates = SNDRV_PCM_RATE_CONTINUOUS,
481 		.rate_min = 4000,
482 		.rate_max = 216000,
483 		.formats = CS4270_FORMATS,
484 	},
485 	.capture = {
486 		.stream_name = "Capture",
487 		.channels_min = 2,
488 		.channels_max = 2,
489 		.rates = SNDRV_PCM_RATE_CONTINUOUS,
490 		.rate_min = 4000,
491 		.rate_max = 216000,
492 		.formats = CS4270_FORMATS,
493 	},
494 	.ops = &cs4270_dai_ops,
495 };
496 
497 /**
498  * cs4270_probe - ASoC probe function
499  * @pdev: platform device
500  *
501  * This function is called when ASoC has all the pieces it needs to
502  * instantiate a sound driver.
503  */
504 static int cs4270_probe(struct snd_soc_codec *codec)
505 {
506 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
507 	int ret;
508 
509 	/* Tell ASoC what kind of I/O to use to read the registers.  ASoC will
510 	 * then do the I2C transactions itself.
511 	 */
512 	ret = snd_soc_codec_set_cache_io(codec, 8, 8, SND_SOC_REGMAP);
513 	if (ret < 0) {
514 		dev_err(codec->dev, "failed to set cache I/O (ret=%i)\n", ret);
515 		return ret;
516 	}
517 
518 	/* Disable auto-mute.  This feature appears to be buggy.  In some
519 	 * situations, auto-mute will not deactivate when it should, so we want
520 	 * this feature disabled by default.  An application (e.g. alsactl) can
521 	 * re-enabled it by using the controls.
522 	 */
523 	ret = snd_soc_update_bits(codec, CS4270_MUTE, CS4270_MUTE_AUTO, 0);
524 	if (ret < 0) {
525 		dev_err(codec->dev, "i2c write failed\n");
526 		return ret;
527 	}
528 
529 	/* Disable automatic volume control.  The hardware enables, and it
530 	 * causes volume change commands to be delayed, sometimes until after
531 	 * playback has started.  An application (e.g. alsactl) can
532 	 * re-enabled it by using the controls.
533 	 */
534 	ret = snd_soc_update_bits(codec, CS4270_TRANS,
535 		CS4270_TRANS_SOFT | CS4270_TRANS_ZERO, 0);
536 	if (ret < 0) {
537 		dev_err(codec->dev, "i2c write failed\n");
538 		return ret;
539 	}
540 
541 	ret = regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
542 				    cs4270->supplies);
543 
544 	return ret;
545 }
546 
547 /**
548  * cs4270_remove - ASoC remove function
549  * @pdev: platform device
550  *
551  * This function is the counterpart to cs4270_probe().
552  */
553 static int cs4270_remove(struct snd_soc_codec *codec)
554 {
555 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
556 
557 	regulator_bulk_disable(ARRAY_SIZE(cs4270->supplies), cs4270->supplies);
558 
559 	return 0;
560 };
561 
562 #ifdef CONFIG_PM
563 
564 /* This suspend/resume implementation can handle both - a simple standby
565  * where the codec remains powered, and a full suspend, where the voltage
566  * domain the codec is connected to is teared down and/or any other hardware
567  * reset condition is asserted.
568  *
569  * The codec's own power saving features are enabled in the suspend callback,
570  * and all registers are written back to the hardware when resuming.
571  */
572 
573 static int cs4270_soc_suspend(struct snd_soc_codec *codec)
574 {
575 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
576 	int reg, ret;
577 
578 	reg = snd_soc_read(codec, CS4270_PWRCTL) | CS4270_PWRCTL_PDN_ALL;
579 	if (reg < 0)
580 		return reg;
581 
582 	ret = snd_soc_write(codec, CS4270_PWRCTL, reg);
583 	if (ret < 0)
584 		return ret;
585 
586 	regulator_bulk_disable(ARRAY_SIZE(cs4270->supplies),
587 			       cs4270->supplies);
588 
589 	return 0;
590 }
591 
592 static int cs4270_soc_resume(struct snd_soc_codec *codec)
593 {
594 	struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
595 	int reg, ret;
596 
597 	ret = regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
598 				    cs4270->supplies);
599 	if (ret != 0)
600 		return ret;
601 
602 	/* In case the device was put to hard reset during sleep, we need to
603 	 * wait 500ns here before any I2C communication. */
604 	ndelay(500);
605 
606 	/* first restore the entire register cache ... */
607 	regcache_sync(cs4270->regmap);
608 
609 	/* ... then disable the power-down bits */
610 	reg = snd_soc_read(codec, CS4270_PWRCTL);
611 	reg &= ~CS4270_PWRCTL_PDN_ALL;
612 
613 	return snd_soc_write(codec, CS4270_PWRCTL, reg);
614 }
615 #else
616 #define cs4270_soc_suspend	NULL
617 #define cs4270_soc_resume	NULL
618 #endif /* CONFIG_PM */
619 
620 /*
621  * ASoC codec driver structure
622  */
623 static const struct snd_soc_codec_driver soc_codec_device_cs4270 = {
624 	.probe =		cs4270_probe,
625 	.remove =		cs4270_remove,
626 	.suspend =		cs4270_soc_suspend,
627 	.resume =		cs4270_soc_resume,
628 
629 	.controls =		cs4270_snd_controls,
630 	.num_controls =		ARRAY_SIZE(cs4270_snd_controls),
631 	.dapm_widgets =		cs4270_dapm_widgets,
632 	.num_dapm_widgets =	ARRAY_SIZE(cs4270_dapm_widgets),
633 	.dapm_routes =		cs4270_dapm_routes,
634 	.num_dapm_routes =	ARRAY_SIZE(cs4270_dapm_routes),
635 };
636 
637 /*
638  * cs4270_of_match - the device tree bindings
639  */
640 static const struct of_device_id cs4270_of_match[] = {
641 	{ .compatible = "cirrus,cs4270", },
642 	{ }
643 };
644 MODULE_DEVICE_TABLE(of, cs4270_of_match);
645 
646 static const struct regmap_config cs4270_regmap = {
647 	.reg_bits =		8,
648 	.val_bits =		8,
649 	.max_register =		CS4270_LASTREG,
650 	.reg_defaults =		cs4270_reg_defaults,
651 	.num_reg_defaults =	ARRAY_SIZE(cs4270_reg_defaults),
652 	.cache_type =		REGCACHE_RBTREE,
653 
654 	.readable_reg =		cs4270_reg_is_readable,
655 	.volatile_reg =		cs4270_reg_is_volatile,
656 };
657 
658 /**
659  * cs4270_i2c_probe - initialize the I2C interface of the CS4270
660  * @i2c_client: the I2C client object
661  * @id: the I2C device ID (ignored)
662  *
663  * This function is called whenever the I2C subsystem finds a device that
664  * matches the device ID given via a prior call to i2c_add_driver().
665  */
666 static int cs4270_i2c_probe(struct i2c_client *i2c_client,
667 	const struct i2c_device_id *id)
668 {
669 	struct device_node *np = i2c_client->dev.of_node;
670 	struct cs4270_private *cs4270;
671 	unsigned int val;
672 	int ret, i;
673 
674 	cs4270 = devm_kzalloc(&i2c_client->dev, sizeof(struct cs4270_private),
675 			      GFP_KERNEL);
676 	if (!cs4270) {
677 		dev_err(&i2c_client->dev, "could not allocate codec\n");
678 		return -ENOMEM;
679 	}
680 
681 	/* get the power supply regulators */
682 	for (i = 0; i < ARRAY_SIZE(supply_names); i++)
683 		cs4270->supplies[i].supply = supply_names[i];
684 
685 	ret = devm_regulator_bulk_get(&i2c_client->dev,
686 				      ARRAY_SIZE(cs4270->supplies),
687 				      cs4270->supplies);
688 	if (ret < 0)
689 		return ret;
690 
691 	/* See if we have a way to bring the codec out of reset */
692 	if (np) {
693 		enum of_gpio_flags flags;
694 		int gpio = of_get_named_gpio_flags(np, "reset-gpio", 0, &flags);
695 
696 		if (gpio_is_valid(gpio)) {
697 			ret = devm_gpio_request_one(&i2c_client->dev, gpio,
698 				     flags & OF_GPIO_ACTIVE_LOW ?
699 					GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH,
700 				     "cs4270 reset");
701 			if (ret < 0)
702 				return ret;
703 		}
704 	}
705 
706 	cs4270->regmap = devm_regmap_init_i2c(i2c_client, &cs4270_regmap);
707 	if (IS_ERR(cs4270->regmap))
708 		return PTR_ERR(cs4270->regmap);
709 
710 	/* Verify that we have a CS4270 */
711 	ret = regmap_read(cs4270->regmap, CS4270_CHIPID, &val);
712 	if (ret < 0) {
713 		dev_err(&i2c_client->dev, "failed to read i2c at addr %X\n",
714 		       i2c_client->addr);
715 		return ret;
716 	}
717 	/* The top four bits of the chip ID should be 1100. */
718 	if ((val & 0xF0) != 0xC0) {
719 		dev_err(&i2c_client->dev, "device at addr %X is not a CS4270\n",
720 		       i2c_client->addr);
721 		return -ENODEV;
722 	}
723 
724 	dev_info(&i2c_client->dev, "found device at i2c address %X\n",
725 		i2c_client->addr);
726 	dev_info(&i2c_client->dev, "hardware revision %X\n", val & 0xF);
727 
728 	i2c_set_clientdata(i2c_client, cs4270);
729 
730 	ret = snd_soc_register_codec(&i2c_client->dev,
731 			&soc_codec_device_cs4270, &cs4270_dai, 1);
732 	return ret;
733 }
734 
735 /**
736  * cs4270_i2c_remove - remove an I2C device
737  * @i2c_client: the I2C client object
738  *
739  * This function is the counterpart to cs4270_i2c_probe().
740  */
741 static int cs4270_i2c_remove(struct i2c_client *i2c_client)
742 {
743 	snd_soc_unregister_codec(&i2c_client->dev);
744 	return 0;
745 }
746 
747 /*
748  * cs4270_id - I2C device IDs supported by this driver
749  */
750 static const struct i2c_device_id cs4270_id[] = {
751 	{"cs4270", 0},
752 	{}
753 };
754 MODULE_DEVICE_TABLE(i2c, cs4270_id);
755 
756 /*
757  * cs4270_i2c_driver - I2C device identification
758  *
759  * This structure tells the I2C subsystem how to identify and support a
760  * given I2C device type.
761  */
762 static struct i2c_driver cs4270_i2c_driver = {
763 	.driver = {
764 		.name = "cs4270",
765 		.owner = THIS_MODULE,
766 		.of_match_table = cs4270_of_match,
767 	},
768 	.id_table = cs4270_id,
769 	.probe = cs4270_i2c_probe,
770 	.remove = cs4270_i2c_remove,
771 };
772 
773 module_i2c_driver(cs4270_i2c_driver);
774 
775 MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
776 MODULE_DESCRIPTION("Cirrus Logic CS4270 ALSA SoC Codec Driver");
777 MODULE_LICENSE("GPL");
778