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Commit 06a67848 authored by Jonathan Cameron's avatar Jonathan Cameron Committed by Jean Delvare
Browse files

i2c: Functions for byte-swapped smbus_write/read_word_data 



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

Signed-off-by: default avatarJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 4403988a

Documentation/i2c/smbus-protocol

+8 −0
Original line number Diff line number Diff line
@@ -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



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()

==============================================
@@ -108,6 +112,10 @@ specified through the Comm byte. 


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()

=============================================

include/linux/i2c.h

+17 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/sched.h>	/* for completion */

#include <linux/mutex.h>

#include <linux/of.h>		/* for struct device_node */

#include <linux/swab.h>		/* for swab16 */



extern struct bus_type i2c_bus_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);

extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,

				     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 */

extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,

				     u8 command, u8 *values);