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cs4270.c

/*
 * 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/platform_device.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>

/*
 * 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.
 *
 * Also note that on the CS4270, the first readable register is 1, but ASoC
 * assumes the first register is 0.  Therfore, the array must have an entry for
 * register 0, but we use cs4270_reg_is_readable() to tell ASoC that it can't
 * be read.
 */
static const u8 cs4270_default_reg_cache[CS4270_LASTREG + 1] = {
      0x00, 0x00, 0x00, 0x30, 0x00, 0x60, 0x20, 0x00, 0x00
};

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

/* Private data for the CS4270 */
00129 struct cs4270_private {
      enum snd_soc_control_type control_type;
      void *control_data;
      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)];
};

/**
 * 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.
 */
00173 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 int cs4270_reg_is_readable(struct snd_soc_codec *codec, unsigned int reg)
{
      return (reg >= CS4270_FIRSTREG) && (reg <= CS4270_LASTREG);
}

static int cs4270_reg_is_volatile(struct snd_soc_codec *codec, 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);
      int ret = 0;

      /* 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");
            ret = -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 */
            ret = -EINVAL;
      }

      return ret;
}

/**
 * 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_pcm_runtime *rtd = substream->private_data;
      struct snd_soc_codec *codec = rtd->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 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 = 1,
            .channels_max = 2,
            .rates = SNDRV_PCM_RATE_CONTINUOUS,
            .rate_min = 4000,
            .rate_max = 216000,
            .formats = CS4270_FORMATS,
      },
      .capture = {
            .stream_name = "Capture",
            .channels_min = 1,
            .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 i, ret;

      codec->control_data = cs4270->control_data;

      /* Tell ASoC what kind of I/O to use to read the registers.  ASoC will
       * then do the I2C transactions itself.
       */
      ret = snd_soc_codec_set_cache_io(codec, 8, 8, cs4270->control_type);
      if (ret < 0) {
            dev_err(codec->dev, "failed to set cache I/O (ret=%i)\n", ret);
            return 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;
      }

      /* Add the non-DAPM controls */
      ret = snd_soc_add_controls(codec, cs4270_snd_controls,
                        ARRAY_SIZE(cs4270_snd_controls));
      if (ret < 0) {
            dev_err(codec->dev, "failed to add controls\n");
            return ret;
      }

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

      ret = regulator_bulk_get(codec->dev, ARRAY_SIZE(cs4270->supplies),
                         cs4270->supplies);
      if (ret < 0)
            return ret;

      ret = regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
                            cs4270->supplies);
      if (ret < 0)
            goto error_free_regulators;

      return 0;

error_free_regulators:
      regulator_bulk_free(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);
      regulator_bulk_free(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, pm_message_t mesg)
{
      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);
      struct i2c_client *i2c_client = codec->control_data;
      int reg;

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

      /* 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 ... */
      for (reg = CS4270_FIRSTREG; reg <= CS4270_LASTREG; reg++) {
            u8 val = snd_soc_read(codec, reg);

            if (i2c_smbus_write_byte_data(i2c_client, reg, val)) {
                  dev_err(codec->dev, "i2c write failed\n");
                  return -EIO;
            }
      }

      /* ... 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 device structure
 *
 * Assign this variable to the codec_dev field of the machine driver's
 * snd_soc_device 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,
      .volatile_register =    cs4270_reg_is_volatile,
      .readable_register =    cs4270_reg_is_readable,
      .reg_cache_size = CS4270_LASTREG + 1,
      .reg_word_size =  sizeof(u8),
      .reg_cache_default =    cs4270_default_reg_cache,
};

/**
 * 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 cs4270_private *cs4270;
      int ret;

      /* Verify that we have a CS4270 */

      ret = i2c_smbus_read_byte_data(i2c_client, CS4270_CHIPID);
      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 ((ret & 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", ret & 0xF);

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

      i2c_set_clientdata(i2c_client, cs4270);
      cs4270->control_data = i2c_client;
      cs4270->control_type = SND_SOC_I2C;

      ret = snd_soc_register_codec(&i2c_client->dev,
                  &soc_codec_device_cs4270, &cs4270_dai, 1);
      if (ret < 0)
            kfree(cs4270);
      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);
      kfree(i2c_get_clientdata(i2c_client));
      return 0;
}

/*
 * cs4270_id - I2C device IDs supported by this driver
 */
static 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-codec",
            .owner = THIS_MODULE,
      },
      .id_table = cs4270_id,
      .probe = cs4270_i2c_probe,
      .remove = cs4270_i2c_remove,
};

static int __init cs4270_init(void)
{
      pr_info("Cirrus Logic CS4270 ALSA SoC Codec Driver\n");

      return i2c_add_driver(&cs4270_i2c_driver);
}
module_init(cs4270_init);

static void __exit cs4270_exit(void)
{
      i2c_del_driver(&cs4270_i2c_driver);
}
module_exit(cs4270_exit);

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

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