linux/sound/soc/codecs/cs4270.c

/*
 * CS4270 ALSA SoC (ASoC) codec driver
 *
 * Author: Timur Tabi <timur@freescale.com>
 *
 * Copyright 2007 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:
 *
 * 1) Software mode is supported.  Stand-alone mode is automatically
 *    selected if I2C is disabled or if a CS4270 is not found on the I2C
 *    bus.  However, stand-alone mode is only partially implemented because
 *    there is no mechanism yet for this driver and the machine driver to
 *    communicate the values of the M0, M1, MCLK1, and MCLK2 pins.
 * 2) Only I2C is supported, not SPI
 * 3) Only Master mode is supported, not Slave.
 * 4) The machine driver's 'startup' function must call
 *    cs4270_set_dai_sysclk() with the value of MCLK.
 * 5) Only I2S and left-justified modes are supported
 * 6) Power management is not supported
 * 7) The only supported control is volume and hardware mute (if enabled)
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <sound/driver.h>
#include <sound/core.h>
#include <sound/soc.h>
#include <sound/initval.h>
#include <linux/i2c.h>

#include "cs4270.h"

/* If I2C is defined, then we support software mode.  However, if we're
   not compiled as module but I2C is, then we can't use I2C calls. */
#if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
#define USE_I2C
#endif

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

/* The number of MCLK/LRCK ratios supported by the CS4270 */
#define NUM_MCLK_RATIOS		9

/* The actual MCLK/LRCK ratios, in increasing numerical order */
static unsigned int mclk_ratios[NUM_MCLK_RATIOS] =
	{64, 96, 128, 192, 256, 384, 512, 768, 1024};

/*
 * Sampling rate <-> bit patter mapping
 *
 * This array maps sampling rates to their SNDRV_PCM_RATE_x equivalent.
 *
 * This is really something that ALSA should provide.
 *
 * This table is used by cs4270_set_dai_sysclk() to tell ALSA which sampling
 * rates the CS4270 currently supports.
 */
static struct {
	unsigned int rate;
	unsigned int bit;
} rate_map[] = {
	{5512, SNDRV_PCM_RATE_5512},
	{8000, SNDRV_PCM_RATE_8000},
	{11025, SNDRV_PCM_RATE_11025},
	{16000, SNDRV_PCM_RATE_16000},
	{22050, SNDRV_PCM_RATE_22050},
	{32000, SNDRV_PCM_RATE_32000},
	{44100, SNDRV_PCM_RATE_44100},
	{48000, SNDRV_PCM_RATE_48000},
	{64000, SNDRV_PCM_RATE_64000},
	{88200, SNDRV_PCM_RATE_88200},
	{96000, SNDRV_PCM_RATE_96000},
	{176400, SNDRV_PCM_RATE_176400},
	{192000, SNDRV_PCM_RATE_192000}
};

/*
 * Determine the CS4270 samples rates.
 *
 * 'freq' is the input frequency to MCLK.  The other parameters are ignored.
 *
 * 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
 * support 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 support 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.
 *
 * Note that in stand-alone mode, the sample rate is determined by input
 * pins M0, M1, MDIV1, and MDIV2.  Also in stand-alone mode, divide-by-3
 * is not a programmable option.  However, divide-by-3 is not an available
 * option in stand-alone mode.  This cases two problems: a ratio of 768 is
 * not available (it requires divide-by-3) and B) ratios 192 and 384 can
 * only be selected with divide-by-1.5, but there is an errate that make
 * this selection difficult.
 *
 * In addition, there is no mechanism for communicating with the machine
 * driver what the input settings can be.  This would need to be implemented
 * for stand-alone mode to work.
 */
static int cs4270_set_dai_sysclk(struct snd_soc_codec_dai *codec_dai,
				 int clk_id, unsigned int freq, int dir)
{
	struct snd_soc_codec *codec = codec_dai->codec;
	struct cs4270_private *cs4270 = codec->private_data;
	unsigned int rates = 0;
	unsigned int rate_min = -1;
	unsigned int rate_max = 0;
	unsigned int i;

	cs4270->mclk = freq;

	for (i = 0; i < NUM_MCLK_RATIOS; i++) {
		unsigned int rate;
		unsigned int j;
		rate = freq / mclk_ratios[i];
		for (j = 0; j < ARRAY_SIZE(rate_map); j++) {
			if (rate == rate_map[j].rate) {
				rates |= rate_map[j].bit;
				if (rate < rate_min)
					rate_min = rate;
				if (rate > rate_max)
					rate_max = rate;
			}
		}
	}

	if (!rates) {
		printk(KERN_ERR "cs4270: could not find a valid sample rate\n");
		return -EINVAL;
	}

	codec_dai->playback.rates = rates;
	codec_dai->playback.rate_min = rate_min;
	codec_dai->playback.rate_max = rate_max;

	codec_dai->capture.rates = rates;
	codec_dai->capture.rate_min = rate_min;
	codec_dai->capture.rate_max = rate_max;

	return 0;
}

/*
 * Configure the codec for the selected audio 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_codec_dai *codec_dai,
			      unsigned int format)
{
	struct snd_soc_codec *codec = codec_dai->codec;
	struct cs4270_private *cs4270 = codec->private_data;
	int ret = 0;

	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:
		printk(KERN_ERR "cs4270: invalid DAI format\n");
		ret = -EINVAL;
	}

	return ret;
}

/*
 * 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)

#ifdef USE_I2C

/* 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)

/* 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_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

/*
 * A list of addresses on which this CS4270 could use.  I2C addresses are
 * 7 bits.  For the CS4270, the upper four bits are always 1001, and the
 * lower three bits are determined via the AD2, AD1, and AD0 pins
 * (respectively).
 */
static unsigned short normal_i2c[] = {
	0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, I2C_CLIENT_END
};
I2C_CLIENT_INSMOD;

/*
 * Pre-fill the CS4270 register cache.
 *
 * We use the auto-increment feature of the CS4270 to read all registers in
 * one shot.
 */
static int cs4270_fill_cache(struct snd_soc_codec *codec)
{
	u8 *cache = codec->reg_cache;
	struct i2c_client *i2c_client = codec->control_data;
	s32 length;

	length = i2c_smbus_read_i2c_block_data(i2c_client,
		CS4270_FIRSTREG | 0x80, CS4270_NUMREGS, cache);

	if (length != CS4270_NUMREGS) {
		printk(KERN_ERR "cs4270: I2C read failure, addr=0x%x\n",
		       i2c_client->addr);
		return -EIO;
	}

	return 0;
}

/*
 * Read from the CS4270 register cache.
 *
 * This CS4270 registers are cached to avoid excessive I2C I/O operations.
 * After the initial read to pre-fill the cache, the CS4270 never updates
 * the register values, so we won't have a cache coherncy problem.
 */
static unsigned int cs4270_read_reg_cache(struct snd_soc_codec *codec,
	unsigned int reg)
{
	u8 *cache = codec->reg_cache;

	if ((reg < CS4270_FIRSTREG) || (reg > CS4270_LASTREG))
		return -EIO;

	return cache[reg - CS4270_FIRSTREG];
}

/*
 * Write to a CS4270 register via the I2C bus.
 *
 * This function writes the given value to the given CS4270 register, and
 * also updates the register cache.
 *
 * Note that we don't use the hw_write function pointer of snd_soc_codec.
 * That's because it's too clunky: the hw_write_t prototype does not match
 * i2c_smbus_write_byte_data(), and it's just another layer of overhead.
 */
static int cs4270_i2c_write(struct snd_soc_codec *codec, unsigned int reg,
			    unsigned int value)
{
	if ((reg < CS4270_FIRSTREG) || (reg > CS4270_LASTREG))
		return -EIO;

	if (i2c_smbus_write_byte_data(codec->control_data, reg, value) == 0) {
		/* We've written to the hardware, so update the cache */
		u8 *cache = codec->reg_cache;
		cache[reg - CS4270_FIRSTREG] = value;
		return 0;
	} else {
		printk(KERN_ERR "cs4270: I2C write of register %u failed\n",
			reg);
		return -EIO;
	}
}

/*
 * Clock Ratio Selection for Master Mode with I2C enabled
 *
 * 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.
 *
 * Each element in this array corresponds to the ratios in mclk_ratios[].
 * These two arrays need to be in sync.
 *
 * '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 = 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.
 */
static struct {
	u8 speed_mode;
	u8 mclk;
} cs4270_mode_ratios[NUM_MCLK_RATIOS] = {
	{CS4270_MODE_4X, CS4270_MODE_DIV1},	/* 64 */
#ifndef CONFIG_SND_SOC_CS4270_VD33_ERRATA
	{CS4270_MODE_4X, CS4270_MODE_DIV15},    /* 96 */
#endif
	{CS4270_MODE_2X, CS4270_MODE_DIV1},     /* 128 */
	{CS4270_MODE_4X, CS4270_MODE_DIV3},     /* 192 */
	{CS4270_MODE_1X, CS4270_MODE_DIV1},     /* 256 */
	{CS4270_MODE_2X, CS4270_MODE_DIV3},     /* 384 */
	{CS4270_MODE_1X, CS4270_MODE_DIV2},     /* 512 */
	{CS4270_MODE_1X, CS4270_MODE_DIV3},     /* 768 */
	{CS4270_MODE_1X, CS4270_MODE_DIV4}      /* 1024 */
};

/*
 * Program the CS4270 with the given hardware parameters.
 *
 * The .dai_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_pcm_runtime *rtd = substream->private_data;
	struct snd_soc_device *socdev = rtd->socdev;
	struct snd_soc_codec *codec = socdev->codec;
	struct cs4270_private *cs4270 = codec->private_data;
	unsigned int ret = 0;
	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 (mclk_ratios[i] == ratio)
			break;
	}

	if (i == NUM_MCLK_RATIOS) {
		/* We did not find a matching ratio */
		printk(KERN_ERR "cs4270: could not find matching ratio\n");
		return -EINVAL;
	}

	/* Freeze and power-down the codec */

	ret = snd_soc_write(codec, CS4270_PWRCTL, CS4270_PWRCTL_FREEZE |
			    CS4270_PWRCTL_PDN_ADC | CS4270_PWRCTL_PDN_DAC |
			    CS4270_PWRCTL_PDN);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: I2C write failed\n");
		return ret;
	}

	/* Program the mode control register */

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

	ret = snd_soc_write(codec, CS4270_MODE, reg);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: I2C write failed\n");
		return ret;
	}

	/* Program the format register */

	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:
		printk(KERN_ERR "cs4270: unknown format\n");
		return -EINVAL;
	}

	ret = snd_soc_write(codec, CS4270_FORMAT, reg);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: I2C write failed\n");
		return ret;
	}

	/* Disable auto-mute.  This feature appears to be buggy, because in
	   some situations, auto-mute will not deactivate when it should. */

	reg = snd_soc_read(codec, CS4270_MUTE);
	reg &= ~CS4270_MUTE_AUTO;
	ret = snd_soc_write(codec, CS4270_MUTE, reg);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: I2C write failed\n");
		return ret;
	}

	/* Thaw and power-up the codec */

	ret = snd_soc_write(codec, CS4270_PWRCTL, 0);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: I2C write failed\n");
		return ret;
	}

	return ret;
}

#ifdef CONFIG_SND_SOC_CS4270_HWMUTE

/*
 * Set the CS4270 external 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_mute(struct snd_soc_codec_dai *dai, int mute)
{
	struct snd_soc_codec *codec = dai->codec;
	int reg6;

	reg6 = snd_soc_read(codec, CS4270_MUTE);

	if (mute)
		reg6 |= CS4270_MUTE_ADC_A | CS4270_MUTE_ADC_B |
			CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B;
	else
		reg6 &= ~(CS4270_MUTE_ADC_A | CS4270_MUTE_ADC_B |
			  CS4270_MUTE_DAC_A | CS4270_MUTE_DAC_B);

	return snd_soc_write(codec, CS4270_MUTE, reg6);
}

#endif

static int cs4270_i2c_probe(struct i2c_adapter *adap, int addr, int kind);

/*
 * Notify the driver that a new I2C bus has been found.
 *
 * This function is called for each I2C bus in the system.  The function
 * then asks the I2C subsystem to probe that bus at the addresses on which
 * our device (the CS4270) could exist.  If a device is found at one of
 * those addresses, then our probe function (cs4270_i2c_probe) is called.
 */
static int cs4270_i2c_attach(struct i2c_adapter *adapter)
{
	return i2c_probe(adapter, &addr_data, cs4270_i2c_probe);
}

static int cs4270_i2c_detach(struct i2c_client *client)
{
	struct snd_soc_codec *codec = i2c_get_clientdata(client);

	i2c_detach_client(client);
	codec->control_data = NULL;

	kfree(codec->reg_cache);
	codec->reg_cache = NULL;

	kfree(client);
	return 0;
}

/* 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, 0)
};

static struct i2c_driver cs4270_i2c_driver = {
	.driver = {
		.name = "CS4270 I2C",
		.owner = THIS_MODULE,
	},
	.id =             I2C_DRIVERID_CS4270,
	.attach_adapter = cs4270_i2c_attach,
	.detach_client =  cs4270_i2c_detach,
};

/*
 * Global variable to store socdev for i2c probe function.
 *
 * If struct i2c_driver had a private_data field, we wouldn't need to use
 * cs4270_socdec.  This is the only way to pass the socdev structure to
 * cs4270_i2c_probe().
 *
 * The real solution to cs4270_socdev is to create a mechanism
 * that maps I2C addresses to snd_soc_device structures.  Perhaps the
 * creation of the snd_soc_device object should be moved out of
 * cs4270_probe() and into cs4270_i2c_probe(), but that would make this
 * driver dependent on I2C.  The CS4270 supports "stand-alone" mode, whereby
 * the chip is *not* connected to the I2C bus, but is instead configured via
 * input pins.
 */
static struct snd_soc_device *cs4270_socdev;

/*
 * Initialize the I2C interface of the CS4270
 *
 * This function is called for whenever the I2C subsystem finds a device
 * at a particular address.
 *
 * Note: snd_soc_new_pcms() must be called before this function can be called,
 * because of snd_ctl_add().
 */
static int cs4270_i2c_probe(struct i2c_adapter *adapter, int addr, int kind)
{
	struct snd_soc_device *socdev = cs4270_socdev;
	struct snd_soc_codec *codec = socdev->codec;
	struct i2c_client *i2c_client = NULL;
	int i;
	int ret = 0;

	/* Probing all possible addresses has one drawback: if there are
	   multiple CS4270s on the bus, then you cannot specify which
	   socdev is matched with which CS4270.  For now, we just reject
	   this I2C device if the socdev already has one attached. */
	if (codec->control_data)
		return -ENODEV;

	/* Note: codec_dai->codec is NULL here */

	i2c_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
	if (!i2c_client) {
		printk(KERN_ERR "cs4270: could not allocate I2C client\n");
		return -ENOMEM;
	}

	codec->reg_cache = kzalloc(CS4270_NUMREGS, GFP_KERNEL);
	if (!codec->reg_cache) {
		printk(KERN_ERR "cs4270: could not allocate register cache\n");
		ret = -ENOMEM;
		goto error;
	}

	i2c_set_clientdata(i2c_client, codec);
	strcpy(i2c_client->name, "CS4270");

	i2c_client->driver = &cs4270_i2c_driver;
	i2c_client->adapter = adapter;
	i2c_client->addr = addr;

	/* Verify that we have a CS4270 */

	ret = i2c_smbus_read_byte_data(i2c_client, CS4270_CHIPID);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: failed to read I2C\n");
		goto error;
	}
	/* The top four bits of the chip ID should be 1100. */
	if ((ret & 0xF0) != 0xC0) {
		/* The device at this address is not a CS4270 codec */
		ret = -ENODEV;
		goto error;
	}

	printk(KERN_INFO "cs4270: found device at I2C address %X\n", addr);
	printk(KERN_INFO "cs4270: hardware revision %X\n", ret & 0xF);

	/* Tell the I2C layer a new client has arrived */

	ret = i2c_attach_client(i2c_client);
	if (ret) {
		printk(KERN_ERR "cs4270: could not attach codec, "
			"I2C address %x, error code %i\n", addr, ret);
		goto error;
	}

	codec->control_data = i2c_client;
	codec->read = cs4270_read_reg_cache;
	codec->write = cs4270_i2c_write;
	codec->reg_cache_size = CS4270_NUMREGS;

	/* The I2C interface is set up, so pre-fill our register cache */

	ret = cs4270_fill_cache(codec);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: failed to fill register cache\n");
		goto error;
	}

	/* Add the non-DAPM controls */

	for (i = 0; i < ARRAY_SIZE(cs4270_snd_controls); i++) {
		struct snd_kcontrol *kctrl =
		snd_soc_cnew(&cs4270_snd_controls[i], codec, NULL);

		ret = snd_ctl_add(codec->card, kctrl);
		if (ret < 0)
			goto error;
	}

	return 0;

error:
	if (codec->control_data) {
		i2c_detach_client(i2c_client);
		codec->control_data = NULL;
	}

	kfree(codec->reg_cache);
	codec->reg_cache = NULL;
	codec->reg_cache_size = 0;

	kfree(i2c_client);

	return ret;
}

#endif

struct snd_soc_codec_dai cs4270_dai = {
	.name = "CS4270",
	.playback = {
		.stream_name = "Playback",
		.channels_min = 1,
		.channels_max = 2,
		.rates = 0,
		.formats = CS4270_FORMATS,
	},
	.capture = {
		.stream_name = "Capture",
		.channels_min = 1,
		.channels_max = 2,
		.rates = 0,
		.formats = CS4270_FORMATS,
	},
	.dai_ops = {
		.set_sysclk = cs4270_set_dai_sysclk,
		.set_fmt = cs4270_set_dai_fmt,
	}
};
EXPORT_SYMBOL_GPL(cs4270_dai);

/*
 * ASoC probe function
 *
 * This function is called when the machine driver calls
 * platform_device_add().
 */
static int cs4270_probe(struct platform_device *pdev)
{
	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
	struct snd_soc_codec *codec;
	int ret = 0;

	printk(KERN_INFO "CS4270 ALSA SoC Codec\n");

	/* Allocate enough space for the snd_soc_codec structure
	   and our private data together. */
	codec = kzalloc(ALIGN(sizeof(struct snd_soc_codec), 4) +
			sizeof(struct cs4270_private), GFP_KERNEL);
	if (!codec) {
		printk(KERN_ERR "cs4270: Could not allocate codec structure\n");
		return -ENOMEM;
	}

	mutex_init(&codec->mutex);
	INIT_LIST_HEAD(&codec->dapm_widgets);
	INIT_LIST_HEAD(&codec->dapm_paths);

	codec->name = "CS4270";
	codec->owner = THIS_MODULE;
	codec->dai = &cs4270_dai;
	codec->num_dai = 1;
	codec->private_data = codec + ALIGN(sizeof(struct snd_soc_codec), 4);

	socdev->codec = codec;

	/* Register PCMs */

	ret = snd_soc_new_pcms(socdev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: failed to create PCMs\n");
		return ret;
	}

#ifdef USE_I2C
	cs4270_socdev = socdev;

	ret = i2c_add_driver(&cs4270_i2c_driver);
	if (ret) {
		printk(KERN_ERR "cs4270: failed to attach driver");
		snd_soc_free_pcms(socdev);
		return ret;
	}

	/* Did we find a CS4270 on the I2C bus? */
	if (codec->control_data) {
		/* Initialize codec ops */
		cs4270_dai.ops.hw_params = cs4270_hw_params;
#ifdef CONFIG_SND_SOC_CS4270_HWMUTE
		cs4270_dai.dai_ops.digital_mute = cs4270_mute;
#endif
	} else
		printk(KERN_INFO "cs4270: no I2C device found, "
			"using stand-alone mode\n");
#else
	printk(KERN_INFO "cs4270: I2C disabled, using stand-alone mode\n");
#endif

	ret = snd_soc_register_card(socdev);
	if (ret < 0) {
		printk(KERN_ERR "cs4270: failed to register card\n");
		snd_soc_free_pcms(socdev);
		return ret;
	}

	return ret;
}

static int cs4270_remove(struct platform_device *pdev)
{
	struct snd_soc_device *socdev = platform_get_drvdata(pdev);

	snd_soc_free_pcms(socdev);

#ifdef USE_I2C
	if (socdev->codec->control_data)
		i2c_del_driver(&cs4270_i2c_driver);
#endif

	kfree(socdev->codec);
	socdev->codec = NULL;

	return 0;
}

/*
 * ASoC codec device structure
 *
 * Assign this variable to the codec_dev field of the machine driver's
 * snd_soc_device structure.
 */
struct snd_soc_codec_device soc_codec_device_cs4270 = {
	.probe = 	cs4270_probe,
	.remove = 	cs4270_remove
};
EXPORT_SYMBOL_GPL(soc_codec_device_cs4270);

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