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regmap: Fix i2c word access when using SMBus access functions 

SMBus access functions assume that 16-bit values are formatted as
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 if a chip is configured as REGMAP_ENDIAN_BIG.
If the chip is configured as REGMAP_ENDIAN_LITTLE, keep using
regmap_smbus_write_word_data and regmap_smbus_read_word_data. Otherwise
reject registration if the controller does not support direct i2c accesses.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Guenter Roeck 2015-02-03 10:01:19 -08:00 committed by Mark Brown
parent 3c174d2926
commit 5892ded23c
1 changed files with 45 additions and 1 deletions
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46
drivers/base/regmap/regmap-i2c.c
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@ -14,6 +14,7 @@
#include <linux/i2c.h>
#include <linux/module.h>
#include "internal.h"
static int regmap_smbus_byte_reg_read(void *context, unsigned int reg,
unsigned int *val)
@ -87,6 +88,42 @@ 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 +217,14 @@ 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 &regmap_smbus_word;
switch (regmap_get_val_endian(&i2c->dev, NULL, config)) {
case REGMAP_ENDIAN_LITTLE:
return &regmap_smbus_word;
case REGMAP_ENDIAN_BIG:
return &regmap_smbus_word_swapped;
default: /* everything else is not supported */
break;
}
else if (config->val_bits == 8 && config->reg_bits == 8 &&
i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_BYTE_DATA))