Commit 5892ded2 authored by Guenter Roeck's avatar Guenter Roeck Committed by Mark Brown
Browse files

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: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 3c174d29

drivers/base/regmap/regmap-i2c.c

+45 −1
Original line number Diff line number Diff line
@@ -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))

		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))

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