1 files changed, 184 insertions, 388 deletions

diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 5d76da43b14c..f46a198a48c0 100644
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -20,40 +20,38 @@
 
 #include <trace/events/asoc.h>
 
-static unsigned int snd_soc_4_12_read(struct snd_soc_codec *codec,
-				     unsigned int reg)
+#if defined(CONFIG_SPI_MASTER)
+static int do_spi_write(void *control_data, const void *msg,
+			int len)
 {
-	int ret;
-	unsigned int val;
+	struct spi_device *spi = control_data;
+	struct spi_transfer t;
+	struct spi_message m;
 
-	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg) ||
-		codec->cache_bypass) {
-			if (codec->cache_only)
-				return -1;
+	if (len <= 0)
+		return 0;
 
-			BUG_ON(!codec->hw_read);
-			return codec->hw_read(codec, reg);
-	}
+	spi_message_init(&m);
+	memset(&t, 0, sizeof t);
 
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-	return val;
+	t.tx_buf = msg;
+	t.len = len;
+
+	spi_message_add_tail(&t, &m);
+	spi_sync(spi, &m);
+
+	return len;
 }
+#endif
 
-static int snd_soc_4_12_write(struct snd_soc_codec *codec, unsigned int reg,
-			     unsigned int value)
+static int do_hw_write(struct snd_soc_codec *codec, unsigned int reg,
+		       unsigned int value, const void *data, int len)
 {
-	u8 data[2];
 	int ret;
 
-	data[0] = (reg << 4) | ((value >> 8) & 0x000f);
-	data[1] = value & 0x00ff;
-
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
+	    reg < codec->driver->reg_cache_size &&
+	    !codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -64,8 +62,8 @@ static int snd_soc_4_12_write(struct snd_soc_codec *codec, unsigned int reg,
 		return 0;
 	}
 
-	ret = codec->hw_write(codec->control_data, data, 2);
-	if (ret == 2)
+	ret = codec->hw_write(codec->control_data, data, len);
+	if (ret == len)
 		return 0;
 	if (ret < 0)
 		return ret;
@@ -73,31 +71,54 @@ static int snd_soc_4_12_write(struct snd_soc_codec *codec, unsigned int reg,
 		return -EIO;
 }
 
+static unsigned int do_hw_read(struct snd_soc_codec *codec, unsigned int reg)
+{
+	int ret;
+	unsigned int val;
+
+	if (reg >= codec->driver->reg_cache_size ||
+	    snd_soc_codec_volatile_register(codec, reg) ||
+	    codec->cache_bypass) {
+		if (codec->cache_only)
+			return -1;
+
+		BUG_ON(!codec->hw_read);
+		return codec->hw_read(codec, reg);
+	}
+
+	ret = snd_soc_cache_read(codec, reg, &val);
+	if (ret < 0)
+		return -1;
+	return val;
+}
+
+static unsigned int snd_soc_4_12_read(struct snd_soc_codec *codec,
+				      unsigned int reg)
+{
+	return do_hw_read(codec, reg);
+}
+
+static int snd_soc_4_12_write(struct snd_soc_codec *codec, unsigned int reg,
+			      unsigned int value)
+{
+	u8 data[2];
+
+	data[0] = (reg << 4) | ((value >> 8) & 0x000f);
+	data[1] = value & 0x00ff;
+
+	return do_hw_write(codec, reg, value, data, 2);
+}
+
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_4_12_spi_write(void *control_data, const char *data,
-				 int len)
+				  int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[2];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[1];
 	msg[1] = data[0];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_4_12_spi_write NULL
@@ -106,81 +127,30 @@ static int snd_soc_4_12_spi_write(void *control_data, const char *data,
 static unsigned int snd_soc_7_9_read(struct snd_soc_codec *codec,
 				     unsigned int reg)
 {
-	int ret;
-	unsigned int val;
-
-	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg) ||
-		codec->cache_bypass) {
-			if (codec->cache_only)
-				return -1;
-
-			BUG_ON(!codec->hw_read);
-			return codec->hw_read(codec, reg);
-	}
-
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-	return val;
+	return do_hw_read(codec, reg);
 }
 
 static int snd_soc_7_9_write(struct snd_soc_codec *codec, unsigned int reg,
 			     unsigned int value)
 {
 	u8 data[2];
-	int ret;
 
 	data[0] = (reg << 1) | ((value >> 8) & 0x0001);
 	data[1] = value & 0x00ff;
 
-	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
-		ret = snd_soc_cache_write(codec, reg, value);
-		if (ret < 0)
-			return -1;
-	}
-
-	if (codec->cache_only) {
-		codec->cache_sync = 1;
-		return 0;
-	}
-
-	ret = codec->hw_write(codec->control_data, data, 2);
-	if (ret == 2)
-		return 0;
-	if (ret < 0)
-		return ret;
-	else
-		return -EIO;
+	return do_hw_write(codec, reg, value, data, 2);
 }
 
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_7_9_spi_write(void *control_data, const char *data,
 				 int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[2];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[0];
 	msg[1] = data[1];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_7_9_spi_write NULL
@@ -190,79 +160,30 @@ static int snd_soc_8_8_write(struct snd_soc_codec *codec, unsigned int reg,
 			     unsigned int value)
 {
 	u8 data[2];
-	int ret;
 
 	reg &= 0xff;
 	data[0] = reg;
 	data[1] = value & 0xff;
 
-	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
-		ret = snd_soc_cache_write(codec, reg, value);
-		if (ret < 0)
-			return -1;
-	}
-
-	if (codec->cache_only) {
-		codec->cache_sync = 1;
-		return 0;
-	}
-
-	if (codec->hw_write(codec->control_data, data, 2) == 2)
-		return 0;
-	else
-		return -EIO;
+	return do_hw_write(codec, reg, value, data, 2);
 }
 
 static unsigned int snd_soc_8_8_read(struct snd_soc_codec *codec,
 				     unsigned int reg)
 {
-	int ret;
-	unsigned int val;
-
-	reg &= 0xff;
-	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg) ||
-		codec->cache_bypass) {
-			if (codec->cache_only)
-				return -1;
-
-			BUG_ON(!codec->hw_read);
-			return codec->hw_read(codec, reg);
-	}
-
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-	return val;
+	return do_hw_read(codec, reg);
 }
 
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_8_8_spi_write(void *control_data, const char *data,
 				 int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[2];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[0];
 	msg[1] = data[1];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_8_8_spi_write NULL
@@ -272,112 +193,78 @@ static int snd_soc_8_16_write(struct snd_soc_codec *codec, unsigned int reg,
 			      unsigned int value)
 {
 	u8 data[3];
-	int ret;
 
 	data[0] = reg;
 	data[1] = (value >> 8) & 0xff;
 	data[2] = value & 0xff;
 
-	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
-		ret = snd_soc_cache_write(codec, reg, value);
-		if (ret < 0)
-			return -1;
-	}
-
-	if (codec->cache_only) {
-		codec->cache_sync = 1;
-		return 0;
-	}
-
-	if (codec->hw_write(codec->control_data, data, 3) == 3)
-		return 0;
-	else
-		return -EIO;
+	return do_hw_write(codec, reg, value, data, 3);
 }
 
 static unsigned int snd_soc_8_16_read(struct snd_soc_codec *codec,
 				      unsigned int reg)
 {
-	int ret;
-	unsigned int val;
-
-	if (reg >= codec->driver->reg_cache_size ||
-	    snd_soc_codec_volatile_register(codec, reg) ||
-	    codec->cache_bypass) {
-		if (codec->cache_only)
-			return -1;
-
-		BUG_ON(!codec->hw_read);
-		return codec->hw_read(codec, reg);
-	}
-
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-	return val;
+	return do_hw_read(codec, reg);
 }
 
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_8_16_spi_write(void *control_data, const char *data,
-				 int len)
+				  int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[3];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[0];
 	msg[1] = data[1];
 	msg[2] = data[2];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_8_16_spi_write NULL
 #endif
 
 #if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
-static unsigned int snd_soc_8_8_read_i2c(struct snd_soc_codec *codec,
-					  unsigned int r)
+static unsigned int do_i2c_read(struct snd_soc_codec *codec,
+				void *reg, int reglen,
+				void *data, int datalen)
 {
 	struct i2c_msg xfer[2];
-	u8 reg = r;
-	u8 data;
 	int ret;
 	struct i2c_client *client = codec->control_data;
 
 	/* Write register */
 	xfer[0].addr = client->addr;
 	xfer[0].flags = 0;
-	xfer[0].len = 1;
-	xfer[0].buf = &reg;
+	xfer[0].len = reglen;
+	xfer[0].buf = reg;
 
 	/* Read data */
 	xfer[1].addr = client->addr;
 	xfer[1].flags = I2C_M_RD;
-	xfer[1].len = 1;
-	xfer[1].buf = &data;
+	xfer[1].len = datalen;
+	xfer[1].buf = data;
 
 	ret = i2c_transfer(client->adapter, xfer, 2);
-	if (ret != 2) {
-		dev_err(&client->dev, "i2c_transfer() returned %d\n", ret);
+	if (ret == 2)
 		return 0;
-	}
+	else if (ret < 0)
+		return ret;
+	else
+		return -EIO;
+}
+#endif
+
+#if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
+static unsigned int snd_soc_8_8_read_i2c(struct snd_soc_codec *codec,
+					 unsigned int r)
+{
+	u8 reg = r;
+	u8 data;
+	int ret;
 
+	ret = do_i2c_read(codec, &reg, 1, &data, 1);
+	if (ret < 0)
+		return 0;
 	return data;
 }
 #else
@@ -388,30 +275,13 @@ static unsigned int snd_soc_8_8_read_i2c(struct snd_soc_codec *codec,
 static unsigned int snd_soc_8_16_read_i2c(struct snd_soc_codec *codec,
 					  unsigned int r)
 {
-	struct i2c_msg xfer[2];
 	u8 reg = r;
 	u16 data;
 	int ret;
-	struct i2c_client *client = codec->control_data;
 
-	/* Write register */
-	xfer[0].addr = client->addr;
-	xfer[0].flags = 0;
-	xfer[0].len = 1;
-	xfer[0].buf = &reg;
-
-	/* Read data */
-	xfer[1].addr = client->addr;
-	xfer[1].flags = I2C_M_RD;
-	xfer[1].len = 2;
-	xfer[1].buf = (u8 *)&data;
-
-	ret = i2c_transfer(client->adapter, xfer, 2);
-	if (ret != 2) {
-		dev_err(&client->dev, "i2c_transfer() returned %d\n", ret);
+	ret = do_i2c_read(codec, &reg, 1, &data, 2);
+	if (ret < 0)
 		return 0;
-	}
-
 	return (data >> 8) | ((data & 0xff) << 8);
 }
 #else
@@ -422,30 +292,13 @@ static unsigned int snd_soc_8_16_read_i2c(struct snd_soc_codec *codec,
 static unsigned int snd_soc_16_8_read_i2c(struct snd_soc_codec *codec,
 					  unsigned int r)
 {
-	struct i2c_msg xfer[2];
 	u16 reg = r;
 	u8 data;
 	int ret;
-	struct i2c_client *client = codec->control_data;
-
-	/* Write register */
-	xfer[0].addr = client->addr;
-	xfer[0].flags = 0;
-	xfer[0].len = 2;
-	xfer[0].buf = (u8 *)&reg;
-
-	/* Read data */
-	xfer[1].addr = client->addr;
-	xfer[1].flags = I2C_M_RD;
-	xfer[1].len = 1;
-	xfer[1].buf = &data;
 
-	ret = i2c_transfer(client->adapter, xfer, 2);
-	if (ret != 2) {
-		dev_err(&client->dev, "i2c_transfer() returned %d\n", ret);
+	ret = do_i2c_read(codec, &reg, 2, &data, 1);
+	if (ret < 0)
 		return 0;
-	}
-
 	return data;
 }
 #else
@@ -453,87 +306,35 @@ static unsigned int snd_soc_16_8_read_i2c(struct snd_soc_codec *codec,
 #endif
 
 static unsigned int snd_soc_16_8_read(struct snd_soc_codec *codec,
-				     unsigned int reg)
+				      unsigned int reg)
 {
-	int ret;
-	unsigned int val;
-
-	reg &= 0xff;
-	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg) ||
-		codec->cache_bypass) {
-			if (codec->cache_only)
-				return -1;
-
-			BUG_ON(!codec->hw_read);
-			return codec->hw_read(codec, reg);
-	}
-
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-	return val;
+	return do_hw_read(codec, reg);
 }
 
 static int snd_soc_16_8_write(struct snd_soc_codec *codec, unsigned int reg,
-			     unsigned int value)
+			      unsigned int value)
 {
 	u8 data[3];
-	int ret;
 
 	data[0] = (reg >> 8) & 0xff;
 	data[1] = reg & 0xff;
 	data[2] = value;
-
 	reg &= 0xff;
-	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
-		ret = snd_soc_cache_write(codec, reg, value);
-		if (ret < 0)
-			return -1;
-	}
 
-	if (codec->cache_only) {
-		codec->cache_sync = 1;
-		return 0;
-	}
-
-	ret = codec->hw_write(codec->control_data, data, 3);
-	if (ret == 3)
-		return 0;
-	if (ret < 0)
-		return ret;
-	else
-		return -EIO;
+	return do_hw_write(codec, reg, value, data, 3);
 }
 
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_16_8_spi_write(void *control_data, const char *data,
-				 int len)
+				  int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[3];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[0];
 	msg[1] = data[1];
 	msg[2] = data[2];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_16_8_spi_write NULL
@@ -543,30 +344,13 @@ static int snd_soc_16_8_spi_write(void *control_data, const char *data,
 static unsigned int snd_soc_16_16_read_i2c(struct snd_soc_codec *codec,
 					   unsigned int r)
 {
-	struct i2c_msg xfer[2];
 	u16 reg = cpu_to_be16(r);
 	u16 data;
 	int ret;
-	struct i2c_client *client = codec->control_data;
-
-	/* Write register */
-	xfer[0].addr = client->addr;
-	xfer[0].flags = 0;
-	xfer[0].len = 2;
-	xfer[0].buf = (u8 *)&reg;
 
-	/* Read data */
-	xfer[1].addr = client->addr;
-	xfer[1].flags = I2C_M_RD;
-	xfer[1].len = 2;
-	xfer[1].buf = (u8 *)&data;
-
-	ret = i2c_transfer(client->adapter, xfer, 2);
-	if (ret != 2) {
-		dev_err(&client->dev, "i2c_transfer() returned %d\n", ret);
+	ret = do_i2c_read(codec, &reg, 2, &data, 2);
+	if (ret < 0)
 		return 0;
-	}
-
 	return be16_to_cpu(data);
 }
 #else
@@ -576,91 +360,82 @@ static unsigned int snd_soc_16_16_read_i2c(struct snd_soc_codec *codec,
 static unsigned int snd_soc_16_16_read(struct snd_soc_codec *codec,
 				       unsigned int reg)
 {
-	int ret;
-	unsigned int val;
-
-	if (reg >= codec->driver->reg_cache_size ||
-	    snd_soc_codec_volatile_register(codec, reg) ||
-	    codec->cache_bypass) {
-		if (codec->cache_only)
-			return -1;
-
-		BUG_ON(!codec->hw_read);
-		return codec->hw_read(codec, reg);
-	}
-
-	ret = snd_soc_cache_read(codec, reg, &val);
-	if (ret < 0)
-		return -1;
-
-	return val;
+	return do_hw_read(codec, reg);
 }
 
 static int snd_soc_16_16_write(struct snd_soc_codec *codec, unsigned int reg,
 			       unsigned int value)
 {
 	u8 data[4];
-	int ret;
 
 	data[0] = (reg >> 8) & 0xff;
 	data[1] = reg & 0xff;
 	data[2] = (value >> 8) & 0xff;
 	data[3] = value & 0xff;
 
-	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size &&
-		!codec->cache_bypass) {
-		ret = snd_soc_cache_write(codec, reg, value);
-		if (ret < 0)
-			return -1;
-	}
-
-	if (codec->cache_only) {
-		codec->cache_sync = 1;
-		return 0;
-	}
-
-	ret = codec->hw_write(codec->control_data, data, 4);
-	if (ret == 4)
-		return 0;
-	if (ret < 0)
-		return ret;
-	else
-		return -EIO;
+	return do_hw_write(codec, reg, value, data, 4);
 }
 
 #if defined(CONFIG_SPI_MASTER)
 static int snd_soc_16_16_spi_write(void *control_data, const char *data,
-				 int len)
+				   int len)
 {
-	struct spi_device *spi = control_data;
-	struct spi_transfer t;
-	struct spi_message m;
 	u8 msg[4];
 
-	if (len <= 0)
-		return 0;
-
 	msg[0] = data[0];
 	msg[1] = data[1];
 	msg[2] = data[2];
 	msg[3] = data[3];
 
-	spi_message_init(&m);
-	memset(&t, 0, sizeof t);
-
-	t.tx_buf = &msg[0];
-	t.len = len;
-
-	spi_message_add_tail(&t, &m);
-	spi_sync(spi, &m);
-
-	return len;
+	return do_spi_write(control_data, msg, len);
 }
 #else
 #define snd_soc_16_16_spi_write NULL
 #endif
 
+/* Primitive bulk write support for soc-cache.  The data pointed to by
+ * `data' needs to already be in the form the hardware expects
+ * including any leading register specific data.  Any data written
+ * through this function will not go through the cache as it only
+ * handles writing to volatile or out of bounds registers.
+ */
+static int snd_soc_hw_bulk_write_raw(struct snd_soc_codec *codec, unsigned int reg,
+				     const void *data, size_t len)
+{
+	int ret;
+
+	/* Ensure that the base register is volatile.  Subsequently
+	 * any other register that is touched by this routine should be
+	 * volatile as well to ensure that we don't get out of sync with
+	 * the cache.
+	 */
+	if (!snd_soc_codec_volatile_register(codec, reg)
+	    && reg < codec->driver->reg_cache_size)
+		return -EINVAL;
+
+	switch (codec->control_type) {
+#if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
+	case SND_SOC_I2C:
+		ret = i2c_master_send(codec->control_data, data, len);
+		break;
+#endif
+#if defined(CONFIG_SPI_MASTER)
+	case SND_SOC_SPI:
+		ret = do_spi_write(codec->control_data, data, len);
+		break;
+#endif
+	default:
+		BUG();
+	}
+
+	if (ret == len)
+		return 0;
+	if (ret < 0)
+		return ret;
+	else
+		return -EIO;
+}
+
 static struct {
 	int addr_bits;
 	int data_bits;
@@ -744,6 +519,7 @@ int snd_soc_codec_set_cache_io(struct snd_soc_codec *codec,
 
 	codec->write = io_types[i].write;
 	codec->read = io_types[i].read;
+	codec->bulk_write_raw = snd_soc_hw_bulk_write_raw;
 
 	switch (control) {
 	case SND_SOC_CUSTOM:
@@ -889,6 +665,8 @@ static int snd_soc_rbtree_cache_sync(struct snd_soc_codec *codec)
 		rbnode = rb_entry(node, struct snd_soc_rbtree_node, node);
 		if (rbnode->value == rbnode->defval)
 			continue;
+		WARN_ON(codec->writable_register &&
+			codec->writable_register(codec, rbnode->reg));
 		ret = snd_soc_cache_read(codec, rbnode->reg, &val);
 		if (ret)
 			return ret;
@@ -1149,6 +927,8 @@ static int snd_soc_lzo_cache_sync(struct snd_soc_codec *codec)
 
 	lzo_blocks = codec->reg_cache;
 	for_each_set_bit(i, lzo_blocks[0]->sync_bmp, lzo_blocks[0]->sync_bmp_nbits) {
+		WARN_ON(codec->writable_register &&
+			codec->writable_register(codec, i));
 		ret = snd_soc_cache_read(codec, i, &val);
 		if (ret)
 			return ret;
@@ -1407,6 +1187,8 @@ static int snd_soc_flat_cache_sync(struct snd_soc_codec *codec)
 
 	codec_drv = codec->driver;
 	for (i = 0; i < codec_drv->reg_cache_size; ++i) {
+		WARN_ON(codec->writable_register &&
+			codec->writable_register(codec, i));
 		ret = snd_soc_cache_read(codec, i, &val);
 		if (ret)
 			return ret;
@@ -1523,7 +1305,7 @@ int snd_soc_cache_init(struct snd_soc_codec *codec)
 				codec->cache_ops->name, codec->name);
 		return codec->cache_ops->init(codec);
 	}
-	return -EINVAL;
+	return -ENOSYS;
 }
 
 /*
@@ -1538,7 +1320,7 @@ int snd_soc_cache_exit(struct snd_soc_codec *codec)
 				codec->cache_ops->name, codec->name);
 		return codec->cache_ops->exit(codec);
 	}
-	return -EINVAL;
+	return -ENOSYS;
 }
 
 /**
@@ -1562,7 +1344,7 @@ int snd_soc_cache_read(struct snd_soc_codec *codec,
 	}
 
 	mutex_unlock(&codec->cache_rw_mutex);
-	return -EINVAL;
+	return -ENOSYS;
 }
 EXPORT_SYMBOL_GPL(snd_soc_cache_read);
 
@@ -1587,7 +1369,7 @@ int snd_soc_cache_write(struct snd_soc_codec *codec,
 	}
 
 	mutex_unlock(&codec->cache_rw_mutex);
-	return -EINVAL;
+	return -ENOSYS;
 }
 EXPORT_SYMBOL_GPL(snd_soc_cache_write);
 
@@ -1610,7 +1392,7 @@ int snd_soc_cache_sync(struct snd_soc_codec *codec)
 	}
 
 	if (!codec->cache_ops || !codec->cache_ops->sync)
-		return -EINVAL;
+		return -ENOSYS;
 
 	if (codec->cache_ops->name)
 		name = codec->cache_ops->name;
@@ -1677,3 +1459,17 @@ int snd_soc_default_readable_register(struct snd_soc_codec *codec,
 	return codec->driver->reg_access_default[index].read;
 }
 EXPORT_SYMBOL_GPL(snd_soc_default_readable_register);
+
+int snd_soc_default_writable_register(struct snd_soc_codec *codec,
+				      unsigned int reg)
+{
+	int index;
+
+	if (reg >= codec->driver->reg_cache_size)
+		return 1;
+	index = snd_soc_get_reg_access_index(codec, reg);
+	if (index < 0)
+		return 0;
+	return codec->driver->reg_access_default[index].write;
+}
+EXPORT_SYMBOL_GPL(snd_soc_default_writable_register);