diff mbox

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

Message ID 1397727612-32103-3-git-send-email-boris.brezillon@free-electrons.com (mailing list archive)
State New, archived
Headers show

Commit Message

Boris BREZILLON April 17, 2014, 9:40 a.m. UTC 
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(-)

Comments

Mark Brown April 18, 2014, 3:10 p.m. UTC | #1 
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.
Lars-Peter Clausen April 18, 2014, 5:08 p.m. UTC | #2 
> +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);
> +}
> +
diff mbox

Patch

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);