[PATCH] i2c: amd756: Fix endianness handling for word data

Atharva Tiwari
2024-12-27T13:22:58Z

Ensure correct handling of "endianness"
for word-sized data in amd756_access

- Convert word data into little-endian using cpu_to_le16
- Convert word data from little-endian
to cpu native format using le16_to_cpu

This fixes poteential issues on big-endian systems and
ensure proper byte ordering for SMBus word transacitions

Signed-off-by: Atharva Tiwari <evepolonium@gmail.com>
---
drivers/i2c/busses/i2c-amd756.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-amd756.c b/drivers/i2c/busses/i2c-amd756.c
index fa0d5a2c3732..f6fe4c32af04 100644
--- a/drivers/i2c/busses/i2c-amd756.c
+++ b/drivers/i2c/busses/i2c-amd756.c
@@ -31,6 +31,7 @@
#include <linux/i2c.h>
#include <linux/acpi.h>
#include <linux/io.h>
+#include <linux/byteorder/generic.h>

/* AMD756 SMBus address offsets */
#define SMB_ADDR_OFFSET 0xE0
@@ -211,7 +212,7 @@ static s32 amd756_access(struct i2c_adapter * adap, u16 addr,
SMB_HOST_ADDRESS);
outb_p(command, SMB_HOST_COMMAND);
if (read_write == I2C_SMBUS_WRITE)
- outw_p(data->word, SMB_HOST_DATA); /* TODO: endian???? */
+ outw_p(cpu_to_le16(data->word), SMB_HOST_DATA);
size = AMD756_WORD_DATA;
break;
case I2C_SMBUS_BLOCK_DATA:
@@ -256,7 +257,7 @@ static s32 amd756_access(struct i2c_adapter * adap, u16 addr,
data->byte = inw_p(SMB_HOST_DATA);
break;
case AMD756_WORD_DATA:
- data->word = inw_p(SMB_HOST_DATA); /* TODO: endian???? */
+ data->word = le16_to_cpu(inw_p(SMB_HOST_DATA));
break;
case AMD756_BLOCK_DATA:
data->block[0] = inw_p(SMB_HOST_DATA) & 0x3f;
--
2.39.5