[PATCH v2 0/2] regmap: support regmap over SMBus

[PATCH v2 0/2] regmap: support regmap over SMBus

[Boris BREZILLON]

Hello,

This patch series adds support for remap over SMBus in case your i2c
adapter does not support regular I2C transfers.

SMBus is a subset of the I2C protocol, often used to access registers
on external devices.

I2C adapters are able to access SMBus devices thanks to the SMBus
emulation layer. In the other hand SMBus adapters may not provide
regular I2C transfers, and thus you may not be able to expose a regmap
if your device is connected to such kind of adapter.
Hence why we need this regmap over SMBus implementation.

Best Regards,

Boris

Changes since v1:
 - add reg_read/reg_write callbacks to the regmap_bus struct

Boris BREZILLON (2):
  regmap: add reg_read/reg_write callbacks to regmap_bus struct
  regmap: i2c: fallback to SMBus if the adapter does not support
    standard I2C

 drivers/base/regmap/regmap-i2c.c | 104 ++++++++++++++++++++++++++++++++++++++-
 drivers/base/regmap/regmap.c     |  26 ++++++++++
 include/linux/regmap.h           |   6 +++
 3 files changed, 134 insertions(+), 2 deletions(-)

-- 
1.8.3.2

[PATCH v2 1/2] regmap: add reg_read/reg_write callbacks to regmap_bus struct

[Boris BREZILLON]

Some busses do not support sending/receiving multiple registers in one go.
Such kind of busses just unpack the registers that have been previously
packed by the regmap core or pack registers that will be later unpacked by
the core code.

Add reg_write and reg_read callbacks in order to optimize access through
this kind of busses.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
---
 drivers/base/regmap/regmap.c | 26 ++++++++++++++++++++++++++
 include/linux/regmap.h       |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index d0a0724..c2a9933 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -35,10 +35,14 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 			       unsigned int mask, unsigned int val,
 			       bool *change);
 
+static int _regmap_bus_reg_read(void *context, unsigned int reg,
+				unsigned int *val);
 static int _regmap_bus_read(void *context, unsigned int reg,
 			    unsigned int *val);
 static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 				       unsigned int val);
+static int _regmap_bus_reg_write(void *context, unsigned int reg,
+				 unsigned int val);
 static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 unsigned int val);
 
@@ -495,6 +499,12 @@ struct regmap *regmap_init(struct device *dev,
 
 		map->defer_caching = false;
 		goto skip_format_initialization;
+	} else if (!bus->read || !bus->write) {
+		map->reg_read = _regmap_bus_reg_read;
+		map->reg_write = _regmap_bus_reg_write;
+
+		map->defer_caching = false;
+		goto skip_format_initialization;
 	} else {
 		map->reg_read  = _regmap_bus_read;
 	}
@@ -1283,6 +1293,14 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 	return ret;
 }
 
+static int _regmap_bus_reg_write(void *context, unsigned int reg,
+				 unsigned int val)
+{
+	struct regmap *map = context;
+
+	return map->bus->reg_write(map->bus_context, reg, val);
+}
+
 static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 unsigned int val)
 {
@@ -1924,6 +1942,14 @@ static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 	return ret;
 }
 
+static int _regmap_bus_reg_read(void *context, unsigned int reg,
+				unsigned int *val)
+{
+	struct regmap *map = context;
+
+	return map->bus->reg_read(map->bus_context, reg, val);
+}
+
 static int _regmap_bus_read(void *context, unsigned int reg,
 			    unsigned int *val)
 {
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 34ef2c7..0c23ed5 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -276,6 +276,10 @@ typedef int (*regmap_hw_async_write)(void *context,
 typedef int (*regmap_hw_read)(void *context,
 			      const void *reg_buf, size_t reg_size,
 			      void *val_buf, size_t val_size);
+typedef int (*regmap_hw_reg_read)(void *context, unsigned int reg,
+				  unsigned int *val);
+typedef int (*regmap_hw_reg_write)(void *context, unsigned int reg,
+				   unsigned int val);
 typedef struct regmap_async *(*regmap_hw_async_alloc)(void);
 typedef void (*regmap_hw_free_context)(void *context);
 
@@ -309,7 +313,9 @@ struct regmap_bus {
 	regmap_hw_write write;
 	regmap_hw_gather_write gather_write;
 	regmap_hw_async_write async_write;
+	regmap_hw_reg_write reg_write;
 	regmap_hw_read read;
+	regmap_hw_reg_read reg_read;
 	regmap_hw_free_context free_context;
 	regmap_hw_async_alloc async_alloc;
 	u8 read_flag_mask;
-- 
1.8.3.2

[PATCH v2 1/2] regmap: add reg_read/reg_write callbacks to regmap_bus struct

[Mark Brown]

On Thu, Apr 17, 2014 at 11:40:11AM +0200, Boris BREZILLON wrote:
> Some busses do not support sending/receiving multiple registers in one go.
> Such kind of busses just unpack the registers that have been previously
> packed by the regmap core or pack registers that will be later unpacked by
> the core code.

Applied, thanks.
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[PATCH v2 2/2] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Boris BREZILLON]

Some I2C adapters are only compatible with the SMBus protocol and do not
support standard I2C transfers.

Fallback to SMBus transfers if we encounter such kind of adapters.
The transfer type is chosen according to the val_bits field in the regmap
config.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
---
 drivers/base/regmap/regmap-i2c.c | 104 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index ebd1895..d82830b 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -14,6 +14,79 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 
+
+static int regmap_smbus_byte_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_byte_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_byte_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xff || reg > 0xff)
+		return -EINVAL;
+
+	return i2c_smbus_write_byte_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_byte = {
+	.reg_write = regmap_smbus_byte_reg_write,
+	.reg_read = regmap_smbus_byte_reg_read,
+};
+
+static int regmap_smbus_word_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xffff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_word_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_word_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xffff || reg > 0xffff)
+		return -EINVAL;
+
+	return i2c_smbus_write_word_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_word = {
+	.reg_write = regmap_smbus_word_reg_write,
+	.reg_read = regmap_smbus_word_reg_read,
+};
+
 static int regmap_i2c_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
@@ -97,6 +170,23 @@ static struct regmap_bus regmap_i2c = {
 	.read = regmap_i2c_read,
 };
 
+const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
+					    const struct regmap_config *config)
+{
+	if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
+		return &regmap_i2c;
+	else if (config->val_bits == 16 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_WORD_DATA))
+		return &regmap_smbus_word;
+	else if (config->val_bits == 8 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_BYTE_DATA))
+		return &regmap_smbus_byte;
+
+	return ERR_PTR(-ENOTSUPP);
+}
+
 /**
  * regmap_init_i2c(): Initialise register map
  *
@@ -109,7 +199,12 @@ static struct regmap_bus regmap_i2c = {
 struct regmap *regmap_init_i2c(struct i2c_client *i2c,
 			       const struct regmap_config *config)
 {
-	return regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_PTR(PTR_ERR(bus));
+
+	return regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(regmap_init_i2c);
 
@@ -126,7 +221,12 @@ EXPORT_SYMBOL_GPL(regmap_init_i2c);
 struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
 				    const struct regmap_config *config)
 {
-	return devm_regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_PTR(PTR_ERR(bus));
+
+	return devm_regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(devm_regmap_init_i2c);
 
-- 
1.8.3.2

[PATCH v2 2/2] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Mark Brown]

On Thu, Apr 17, 2014 at 11:40:12AM +0200, Boris BREZILLON wrote:

> +const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
> +					    const struct regmap_config *config)

Non-exported functions should be static.  Otherwise this looks good
modulo the register size issue that Guenter identified.
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[PATCH v2 2/2] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Lars-Peter Clausen]

> +const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
> +					    const struct regmap_config *config)
> +{
> +	if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
> +		return &regmap_i2c;
> +	else if (config->val_bits == 16 &&
> +		 i2c_check_functionality(i2c->adapter,
> +					 I2C_FUNC_SMBUS_WORD_DATA))
> +		return &regmap_smbus_word;
> +	else if (config->val_bits == 8 &&
> +		 i2c_check_functionality(i2c->adapter,
> +					 I2C_FUNC_SMBUS_BYTE_DATA))
> +		return &regmap_smbus_byte;

The fallback code should also check that reg_bits is 8.

> +
> +	return ERR_PTR(-ENOTSUPP);
> +}
> +

[PATCH v3] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Boris BREZILLON]

Some I2C adapters are only compatible with the SMBus protocol and do not
support standard I2C transfers.

Fallback to SMBus transfers if we encounter such kind of adapters.
The transfer type is chosen according to the val_bits field in the regmap
config.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
---
Changes since v2:
- fix regmap_get_i2c_bus scope (declare as static)
- fix reg width check in reg_read/write functions
- add reg_bits check in regmap_get_i2c_bus function
- 

 drivers/base/regmap/regmap-i2c.c | 104 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index ebd1895..0a43211 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -14,6 +14,79 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 
+
+static int regmap_smbus_byte_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_byte_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_byte_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xff || reg > 0xff)
+		return -EINVAL;
+
+	return i2c_smbus_write_byte_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_byte = {
+	.reg_write = regmap_smbus_byte_reg_write,
+	.reg_read = regmap_smbus_byte_reg_read,
+};
+
+static int regmap_smbus_word_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_word_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_word_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xffff || reg > 0xff)
+		return -EINVAL;
+
+	return i2c_smbus_write_word_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_word = {
+	.reg_write = regmap_smbus_word_reg_write,
+	.reg_read = regmap_smbus_word_reg_read,
+};
+
 static int regmap_i2c_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
@@ -97,6 +170,23 @@ static struct regmap_bus regmap_i2c = {
 	.read = regmap_i2c_read,
 };
 
+static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
+					const struct regmap_config *config)
+{
+	if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
+		return &regmap_i2c;
+	else if (config->val_bits == 16 && config->reg_bits == 8 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_WORD_DATA))
+		return &regmap_smbus_word;
+	else if (config->val_bits == 8 && config->reg_bits == 8 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_BYTE_DATA))
+		return &regmap_smbus_byte;
+
+	return ERR_PTR(-ENOTSUPP);
+}
+
 /**
  * regmap_init_i2c(): Initialise register map
  *
@@ -109,7 +199,12 @@ static struct regmap_bus regmap_i2c = {
 struct regmap *regmap_init_i2c(struct i2c_client *i2c,
 			       const struct regmap_config *config)
 {
-	return regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_PTR(PTR_ERR(bus));
+
+	return regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(regmap_init_i2c);
 
@@ -126,7 +221,12 @@ EXPORT_SYMBOL_GPL(regmap_init_i2c);
 struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
 				    const struct regmap_config *config)
 {
-	return devm_regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_PTR(PTR_ERR(bus));
+
+	return devm_regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(devm_regmap_init_i2c);
 
-- 
1.8.3.2

[PATCH v3] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Guenter Roeck]

On 04/18/2014 01:11 PM, Boris BREZILLON wrote:
> Some I2C adapters are only compatible with the SMBus protocol and do not
> support standard I2C transfers.
>
> Fallback to SMBus transfers if we encounter such kind of adapters.
> The transfer type is chosen according to the val_bits field in the regmap
> config.
>
> Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
> ---

[ ... ]

>   /**
>    * regmap_init_i2c(): Initialise register map
>    *
> @@ -109,7 +199,12 @@ static struct regmap_bus regmap_i2c = {
>   struct regmap *regmap_init_i2c(struct i2c_client *i2c,
>   			       const struct regmap_config *config)
>   {
> -	return regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
> +	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
> +
> +	if (IS_ERR(bus))
> +		return ERR_PTR(PTR_ERR(bus));
> +
This seems clumsy. You should be able to use ERR_CAST() instead.
Also see Documentation/coccinelle.txt and scripts/coccinelle/api/err_cast.cocci.

> +	return regmap_init(&i2c->dev, bus, &i2c->dev, config);
>   }
>   EXPORT_SYMBOL_GPL(regmap_init_i2c);
>
> @@ -126,7 +221,12 @@ EXPORT_SYMBOL_GPL(regmap_init_i2c);
>   struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
>   				    const struct regmap_config *config)
>   {
> -	return devm_regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
> +	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
> +
> +	if (IS_ERR(bus))
> +		return ERR_PTR(PTR_ERR(bus));
> +
Same here.

Guenter

[PATCH v4] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Boris BREZILLON]

Some I2C adapters are only compatible with the SMBus protocol and do not
support standard I2C transfers.

Fallback to SMBus transfers if we encounter such kind of adapters.
The transfer type is chosen according to the val_bits field in the regmap
config.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
---
Changes since v3:
- make use of ERR_CAST instead of ERR_PTR + PTR_ERR

Changes since v2:
- fix regmap_get_i2c_bus scope (declare as static)
- fix reg width check in reg_read/write functions
- add reg_bits check in regmap_get_i2c_bus function


 drivers/base/regmap/regmap-i2c.c | 104 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index ebd1895..ca193d1 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -14,6 +14,79 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 
+
+static int regmap_smbus_byte_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_byte_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_byte_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xff || reg > 0xff)
+		return -EINVAL;
+
+	return i2c_smbus_write_byte_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_byte = {
+	.reg_write = regmap_smbus_byte_reg_write,
+	.reg_read = regmap_smbus_byte_reg_read,
+};
+
+static int regmap_smbus_word_reg_read(void *context, unsigned int reg,
+				      unsigned int *val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_word_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int regmap_smbus_word_reg_write(void *context, unsigned int reg,
+				       unsigned int val)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (val > 0xffff || reg > 0xff)
+		return -EINVAL;
+
+	return i2c_smbus_write_word_data(i2c, reg, val);
+}
+
+static struct regmap_bus regmap_smbus_word = {
+	.reg_write = regmap_smbus_word_reg_write,
+	.reg_read = regmap_smbus_word_reg_read,
+};
+
 static int regmap_i2c_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
@@ -97,6 +170,23 @@ static struct regmap_bus regmap_i2c = {
 	.read = regmap_i2c_read,
 };
 
+static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
+					const struct regmap_config *config)
+{
+	if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
+		return &regmap_i2c;
+	else if (config->val_bits == 16 && config->reg_bits == 8 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_WORD_DATA))
+		return &regmap_smbus_word;
+	else if (config->val_bits == 8 && config->reg_bits == 8 &&
+		 i2c_check_functionality(i2c->adapter,
+					 I2C_FUNC_SMBUS_BYTE_DATA))
+		return &regmap_smbus_byte;
+
+	return ERR_PTR(-ENOTSUPP);
+}
+
 /**
  * regmap_init_i2c(): Initialise register map
  *
@@ -109,7 +199,12 @@ static struct regmap_bus regmap_i2c = {
 struct regmap *regmap_init_i2c(struct i2c_client *i2c,
 			       const struct regmap_config *config)
 {
-	return regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(regmap_init_i2c);
 
@@ -126,7 +221,12 @@ EXPORT_SYMBOL_GPL(regmap_init_i2c);
 struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
 				    const struct regmap_config *config)
 {
-	return devm_regmap_init(&i2c->dev, &regmap_i2c, &i2c->dev, config);
+	const struct regmap_bus *bus = regmap_get_i2c_bus(i2c, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return devm_regmap_init(&i2c->dev, bus, &i2c->dev, config);
 }
 EXPORT_SYMBOL_GPL(devm_regmap_init_i2c);
 
-- 
1.8.3.2

[PATCH v4] regmap: i2c: fallback to SMBus if the adapter does not support standard I2C

[Mark Brown]

On Mon, Apr 21, 2014 at 10:56:59PM +0200, Boris BREZILLON wrote:
> Some I2C adapters are only compatible with the SMBus protocol and do not
> support standard I2C transfers.

Applied, thanks.
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