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i2c: Functions for byte-swapped smbus_write/read_word_data

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Reimplemented at least 17 times discounting error mangling cases
where it could be used.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Jonathan Cameron 2011-10-30 13:47:25 +01:00 committed by Jean Delvare
parent 4403988afc
commit 06a67848c6
2 changed files with 25 additions and 0 deletions
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8
Documentation/i2c/smbus-protocol
View file

@ -88,6 +88,10 @@ byte. But this time, the data is a complete word (16 bits).
S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
Note the convenience function i2c_smbus_read_word_swapped is
available for reads where the two data bytes are the other way
around (not SMBus compliant, but very popular.)
SMBus Write Byte: i2c_smbus_write_byte_data() SMBus Write Byte: i2c_smbus_write_byte_data()
============================================== ==============================================
@ -108,6 +112,10 @@ specified through the Comm byte.
S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
Note the convenience function i2c_smbus_write_word_swapped is
available for writes where the two data bytes are the other way
around (not SMBus compliant, but very popular.)
SMBus Process Call: i2c_smbus_process_call() SMBus Process Call: i2c_smbus_process_call()
============================================= =============================================

17
include/linux/i2c.h
View file

@ -34,6 +34,7 @@
#include <linux/sched.h> /* for completion */ #include <linux/sched.h> /* for completion */
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/of.h> /* for struct device_node */ #include <linux/of.h> /* for struct device_node */
#include <linux/swab.h> /* for swab16 */
extern struct bus_type i2c_bus_type; extern struct bus_type i2c_bus_type;
extern struct device_type i2c_adapter_type; extern struct device_type i2c_adapter_type;
@ -88,6 +89,22 @@ extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
u8 command); u8 command);
extern s32 i2c_smbus_write_word_data(const struct i2c_client *client, extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
u8 command, u16 value); u8 command, u16 value);
static inline s32
i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
{
s32 value = i2c_smbus_read_word_data(client, command);
return (value < 0) ? value : swab16(value);
}
static inline s32
i2c_smbus_write_word_swapped(const struct i2c_client *client,
u8 command, u16 value)
{
return i2c_smbus_write_word_data(client, command, swab16(value));
}
/* Returns the number of read bytes */ /* Returns the number of read bytes */
extern s32 i2c_smbus_read_block_data(const struct i2c_client *client, extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
u8 command, u8 *values); u8 command, u8 *values);