i2c-stub: Use a single array for byte and word operations

This mimics the behavior of actual SMBus chips better.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Mark M. Hoffman <mhoffman@lightlink.com>

2 files changed, 8 insertions, 10 deletions

diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub
index 41889c091a37..0d8be1c20c16 100644
--- a/Documentation/i2c/i2c-stub
+++ b/Documentation/i2c/i2c-stub
@@ -35,9 +35,6 @@ int chip_addr[10]:
 
 CAVEATS:
 
-There are independent arrays for byte/data and word/data commands.  Depending
-on if/how a target driver mixes them, you'll need to be careful.
-
 If your target driver polls some byte or word waiting for it to change, the
 stub could lock it up.  Use i2cset to unlock it.
 
diff --git a/drivers/i2c/busses/i2c-stub.c b/drivers/i2c/busses/i2c-stub.c
index 84df29da1ddc..c2a9f8c94f5e 100644
--- a/drivers/i2c/busses/i2c-stub.c
+++ b/drivers/i2c/busses/i2c-stub.c
@@ -1,8 +1,8 @@
 /*
-    i2c-stub.c - Part of lm_sensors, Linux kernel modules for hardware
-              monitoring
+    i2c-stub.c - I2C/SMBus chip emulator
 
     Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
+    Copyright (C) 2007 Jean Delvare <khali@linux-fr.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -37,8 +37,8 @@ MODULE_PARM_DESC(chip_addr,
 
 struct stub_chip {
         u8 pointer;
-        u8 bytes[256];
-        u16 words[256];
+        u16 words[256];         /* Byte operations use the LSB as per SMBus
+                                   specification */
 };
 
 static struct stub_chip *stub_chips;
@@ -75,7 +75,7 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
                                         "wrote 0x%02x.\n",
                                         addr, command);
                 } else {
-                        data->byte = chip->bytes[chip->pointer++];
+                        data->byte = chip->words[chip->pointer++] & 0xff;
                         dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
                                         "read  0x%02x.\n",
                                         addr, data->byte);
@@ -86,12 +86,13 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
 
         case I2C_SMBUS_BYTE_DATA:
                 if (read_write == I2C_SMBUS_WRITE) {
-                        chip->bytes[command] = data->byte;
+                        chip->words[command] &= 0xff00;
+                        chip->words[command] |= data->byte;
                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
                                         "wrote 0x%02x at 0x%02x.\n",
                                         addr, data->byte, command);
                 } else {
-                        data->byte = chip->bytes[command];
+                        data->byte = chip->words[command] & 0xff;
                         dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
                                         "read  0x%02x at 0x%02x.\n",
                                         addr, data->byte, command);