[ALSA] ASoC CS4270 codec device driver

This patch adds ALSA SoC support for the Cirrus Logic CS4270 codec.  The
following features are suppored:
1) Stand-alone and software mode
2) Software mode via I2C only
3) Master mode, not Slave
4) No power management

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

4 files changed, 858 insertions, 0 deletions

diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index e5fb437b86e8..78248808a9d8 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -17,3 +17,23 @@ config SND_SOC_WM8753
 config SND_SOC_WM9712
         tristate
         depends on SND_SOC
+
+# Cirrus Logic CS4270 Codec
+config SND_SOC_CS4270
+        tristate
+        depends on SND_SOC
+
+# Cirrus Logic CS4270 Codec Hardware Mute Support
+# Select if you have external muting circuitry attached to your CS4270.
+config SND_SOC_CS4270_HWMUTE
+        bool
+        depends on SND_SOC_CS4270
+
+# Cirrus Logic CS4270 Codec VD = 3.3V Errata
+# Select if you are affected by the errata where the part will not function
+# if MCLK divide-by-1.5 is selected and VD is set to 3.3V.  The driver will
+# not select any sample rates that require MCLK to be divided by 1.5.
+config SND_SOC_CS4270_VD33_ERRATA
+        bool
+        depends on SND_SOC_CS4270
+
diff --git a/sound/soc/codecs/Makefile b/sound/soc/codecs/Makefile
index e39a747a17cf..7ad78e36d506 100644
--- a/sound/soc/codecs/Makefile
+++ b/sound/soc/codecs/Makefile
@@ -3,9 +3,11 @@ snd-soc-wm8731-objs := wm8731.o
 snd-soc-wm8750-objs := wm8750.o
 snd-soc-wm8753-objs := wm8753.o
 snd-soc-wm9712-objs := wm9712.o
+snd-soc-cs4270-objs := cs4270.o
 
 obj-$(CONFIG_SND_SOC_AC97_CODEC)        += snd-soc-ac97.o
 obj-$(CONFIG_SND_SOC_WM8731)    += snd-soc-wm8731.o
 obj-$(CONFIG_SND_SOC_WM8750)    += snd-soc-wm8750.o
 obj-$(CONFIG_SND_SOC_WM8753)    += snd-soc-wm8753.o
 obj-$(CONFIG_SND_SOC_WM9712)    += snd-soc-wm9712.o
+obj-$(CONFIG_SND_SOC_CS4270)    += snd-soc-cs4270.o
diff --git a/sound/soc/codecs/cs4270.c b/sound/soc/codecs/cs4270.c
new file mode 100644
index 000000000000..b659a5dfd776
--- /dev/null
+++ b/sound/soc/codecs/cs4270.c
@@ -0,0 +1,808 @@
+/*
+ * 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) Stand-alone and software mode is supported.  Stand-alone is
+ *    automatically selected if I2C is disabled or if a CS4270 is not found
+ *    on the I2C bus.
+ * 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"
+
+/* 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 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 CONFIG_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=%u\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 failed\n");
+                return -EIO;
+        }
+}
+
+/*
+ * Clock Ratio Selection for Master Mode.
+ *
+ * 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.
+ *
+ * 'ratio' is the MCLK/LRCK ratio.  MCLK is usually a fixed input frequency,
+ * and LRCK is equal to the sampling rate. The CS4270 only supports sampling
+ * rates where this ratio is one of: 64, 96, 128, 192, 256, 384, 512, 768 or
+ * 1024.
+ *
+ * '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 {
+        unsigned int ratio;
+        u8 speed_mode;
+        u8 mclk;
+} 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}
+};
+
+/*
+ * 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 < ARRAY_SIZE(cs4270_mode_ratios); i++) {
+                if (cs4270_mode_ratios[i].ratio == ratio)
+                        break;
+        }
+
+        if (i == ARRAY_SIZE(cs4270_mode_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
+
+/*
+ * 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.
+ */
+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 < ARRAY_SIZE(cs4270_mode_ratios); i++) {
+                unsigned int rate;
+                unsigned int j;
+                rate = freq / cs4270_mode_ratios[i].ratio;
+                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 (!rate_max) {
+                printk(KERN_ERR "cs4270: could not find a valid 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;
+}
+
+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 CONFIG_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 CONFIG_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");
diff --git a/sound/soc/codecs/cs4270.h b/sound/soc/codecs/cs4270.h
new file mode 100644
index 000000000000..0ced49b7804d
--- /dev/null
+++ b/sound/soc/codecs/cs4270.h
@@ -0,0 +1,28 @@
+/*
+ * Cirrus Logic CS4270 ALSA SoC 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.
+ */
+
+#ifndef _CS4270_H
+#define _CS4270_H
+
+/*
+ * The ASoC codec DAI structure for the CS4270.  Assign this structure to
+ * the .codec_dai field of your machine driver's snd_soc_dai_link structure.
+ */
+extern struct snd_soc_codec_dai cs4270_dai;
+
+/*
+ * The ASoC codec device structure for the CS4270.  Assign this structure
+ * to the .codec_dev field of your machine driver's snd_soc_device
+ * structure.
+ */
+extern struct snd_soc_codec_device soc_codec_device_cs4270;
+
+#endif