From 06a67848c6681a73e621e47c056490d51a07289f Mon Sep 17 00:00:00 2001
From: Jonathan Cameron <jic23@cam.ac.uk>
Date: Sun, 30 Oct 2011 13:47:25 +0100
Subject: [PATCH] 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: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
Documentation/i2c/smbus-protocol | 8 ++++++++
include/linux/i2c.h | 17 +++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/Documentation/i2c/smbus-protocol b/Documentation/i2c/smbus-protocol
index 7c19d1a2bea0a..49f5b680809d9 100644
--- a/Documentation/i2c/smbus-protocol
+++ b/Documentation/i2c/smbus-protocol
@@ -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()
=============================================
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index a6c652ef516d5..38a21c3edd2cb 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -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);
--
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