[PATCH v2 1/2] regmap: Export regmap_get_val_endian

[PATCH v2 1/2] regmap: Export regmap_get_val_endian

[Guenter Roeck]

We'll need to call it from regmap-i2c.c, which can be built as module.

Cc: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: New patch

 drivers/base/regmap/internal.h | 4 ++++
 drivers/base/regmap/regmap.c   | 7 ++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 0da5865..c49a79e 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -233,6 +233,10 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 
 void regmap_async_complete_cb(struct regmap_async *async, int ret);
 
+enum regmap_endian regmap_get_val_endian(struct device *dev,
+					 const struct regmap_bus *bus,
+					 const struct regmap_config *config);
+
 extern struct regcache_ops regcache_rbtree_ops;
 extern struct regcache_ops regcache_lzo_ops;
 extern struct regcache_ops regcache_flat_ops;
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index d2f8a81..f99b098 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -473,9 +473,9 @@ static enum regmap_endian regmap_get_reg_endian(const struct regmap_bus *bus,
 	return REGMAP_ENDIAN_BIG;
 }
 
-static enum regmap_endian regmap_get_val_endian(struct device *dev,
-					const struct regmap_bus *bus,
-					const struct regmap_config *config)
+enum regmap_endian regmap_get_val_endian(struct device *dev,
+					 const struct regmap_bus *bus,
+					 const struct regmap_config *config)
 {
 	struct device_node *np;
 	enum regmap_endian endian;
@@ -513,6 +513,7 @@ static enum regmap_endian regmap_get_val_endian(struct device *dev,
 	/* Use this if no other value was found */
 	return REGMAP_ENDIAN_BIG;
 }
+EXPORT_SYMBOL_GPL(regmap_get_val_endian);
 
 /**
  * regmap_init(): Initialise register map
-- 
2.1.0

[PATCH v2 2/2] regmap: Fix i2c word access when using SMBus access functions

[Guenter Roeck]

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.

Cc: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: SMBUs -> SMBus, 16 bit -> 16-bit in commit log
    Use regmap_get_val_endian to get configured chip endianness
    Only accept REGMAP_ENDIAN_LITTLE and REGMAP_ENDIAN_BIG for SMBus 16-bit
    accesses

 drivers/base/regmap/regmap-i2c.c | 46 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 053150a..4b76e33 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))
-- 
2.1.0

Re: [PATCH v2 1/2] regmap: Export regmap_get_val_endian

[Mark Brown]

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On Tue, Feb 03, 2015 at 10:01:18AM -0800, Guenter Roeck wrote:
> We'll need to call it from regmap-i2c.c, which can be built as module.

Applied both, thanks.

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