i2c-stub: Allow user to disable some commands

Add a module parameter to override the functionality bitfield. This
lets the user disable some commands. This can be used to force a chip
driver to take different code paths.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/i2c/busses/i2c-stub.c b/drivers/i2c/busses/i2c-stub.c
index 52ebeda1a64b..0c770eabe85e 100644
--- a/drivers/i2c/busses/i2c-stub.c
+++ b/drivers/i2c/busses/i2c-stub.c
@@ -35,6 +35,10 @@ module_param_array(chip_addr, ushort, NULL, S_IRUGO);
 MODULE_PARM_DESC(chip_addr,
                  "Chip addresses (up to 10, between 0x03 and 0x77)");
 
+static unsigned long functionality = ~0UL;
+module_param(functionality, ulong, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(functionality, "Override functionality bitfield");
+
 struct stub_chip {
         u8 pointer;
         u16 words[256];         /* Byte operations use the LSB as per SMBus
@@ -152,9 +156,9 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
 
 static u32 stub_func(struct i2c_adapter *adapter)
 {
-        return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
+        return (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
                 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
-                I2C_FUNC_SMBUS_I2C_BLOCK;
+                I2C_FUNC_SMBUS_I2C_BLOCK) & functionality;
 }
 
 static const struct i2c_algorithm smbus_algorithm = {