Hi Guenter,
On Sun, 1 Feb 2015 15:48:01 -0800, Guenter Roeck wrote:
> SMBUs access functions assume that 16 bit values are formatted as
Correct spelling is SMBus (lowercase U.) Also I think "16 bit" is
better spelled "16-bit" (more occurrences below.)
> little endian numbers. The direct i2c access functions in regmap,
> however, assume that 16 bit values are formatted as big endian numbers.
> As a result, the current code returns different values if an i2c chip's
> 16 bit registers are accessed through i2c access functions vs. SMBus
> access functions.
>
> Use regmap_smbus_read_word_swapped and regmap_smbus_write_word_swapped
> for 16 bit SMBus accesses unless a chip is registered with val_format_endian
> set to REGMAP_ENDIAN_LITTLE. In the latter case, keep using
> regmap_smbus_write_word_data and regmap_smbus_read_word_data.
>
> Cc: Jean Delvare <jdelv...@suse.de>
> Signed-off-by: Guenter Roeck <li...@roeck-us.net>
> ---
> Might be a candidate for -stable, though as far as I can see there is
> currently
> no driver in the upstream kernel using regmap for 16-bit i2c accesses.
>
> drivers/base/regmap/regmap-i2c.c | 41
> +++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/regmap/regmap-i2c.c
> b/drivers/base/regmap/regmap-i2c.c
> index 053150a..865f4f8 100644
> --- a/drivers/base/regmap/regmap-i2c.c
> +++ b/drivers/base/regmap/regmap-i2c.c
> @@ -87,6 +87,42 @@ static struct regmap_bus regmap_smbus_word = {
> .reg_read = regmap_smbus_word_reg_read,
> };
>
> +static int regmap_smbus_word_read_swapped(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_swapped(i2c, reg);
> + if (ret < 0)
> + return ret;
> +
> + *val = ret;
> +
> + return 0;
> +}
> +
> +static int regmap_smbus_word_write_swapped(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_swapped(i2c, reg, val);
> +}
> +
> +static struct regmap_bus regmap_smbus_word_swapped = {
> + .reg_write = regmap_smbus_word_write_swapped,
> + .reg_read = regmap_smbus_word_read_swapped,
> +};
> +
> static int regmap_i2c_write(void *context, const void *data, size_t count)
> {
> struct device *dev = context;
> @@ -180,7 +216,10 @@ static const struct regmap_bus
> *regmap_get_i2c_bus(struct i2c_client *i2c,
> else if (config->val_bits == 16 && config->reg_bits == 8 &&
> i2c_check_functionality(i2c->adapter,
> I2C_FUNC_SMBUS_WORD_DATA))
> - return ®map_smbus_word;
> + if (config->val_format_endian == REGMAP_ENDIAN_LITTLE)
> + return ®map_smbus_word;
> + else
> + return ®map_smbus_word_swapped;
Indentation looks wrong.
> else if (config->val_bits == 8 && config->reg_bits == 8 &&
> i2c_check_functionality(i2c->adapter,
> I2C_FUNC_SMBUS_BYTE_DATA))
The code itself looks sane, although I am not a regmap expert.
Reviewed-by: Jean Delvare <jdelv...@suse.de>
--
Jean Delvare
SUSE L3 Support
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