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authorGuenter Roeck <linux@roeck-us.net>2015-02-03 21:01:19 +0300
committerMark Brown <broonie@kernel.org>2015-02-04 23:48:13 +0300
commit5892ded23c8e9e015b01347222ba4de8a80e7ce2 (patch)
tree24a8457b9c79c08289add18d09c07ed6cb22c9ae /drivers/base
parent3c174d29263b1954171cf857a9bf59dcbe527875 (diff)
downloadlinux-5892ded23c8e9e015b01347222ba4de8a80e7ce2.tar.xz
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>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/regmap/regmap-i2c.c46
1 files changed, 45 insertions, 1 deletions
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 053150a7f9f2..4b76e33110a2 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -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))