return 0;
 }
 
+#define enable_flag(x) (x)
+#define disable_flag(x) 0
+#define enable_flag_if(x, cond) ((cond) ? (x) : 0)
+
 static u32 i801_func(struct i2c_adapter *adapter)
 {
        struct i2c_device *priv = i2c_get_adapdata(adapter);
        // http://lxr.free-electrons.com/source/include/uapi/linux/i2c.h#L85
 
        u32 f =
-               I2C_FUNC_I2C                     | /* 0x00000001(I enabled this
-                                                   * one)
-                                                   */
-               !I2C_FUNC_10BIT_ADDR             |              /* 0x00000002 */
-               !I2C_FUNC_PROTOCOL_MANGLING      |              /* 0x00000004 */
-               ((priv->features & FEATURE_SMBUS_PEC) ?
-                       I2C_FUNC_SMBUS_PEC : 0)  |              /* 0x00000008 */
-               !I2C_FUNC_SMBUS_BLOCK_PROC_CALL  |              /* 0x00008000 */
-               I2C_FUNC_SMBUS_QUICK             |              /* 0x00010000 */
-               !I2C_FUNC_SMBUS_READ_BYTE        |              /* 0x00020000 */
-               !I2C_FUNC_SMBUS_WRITE_BYTE       |              /* 0x00040000 */
-               !I2C_FUNC_SMBUS_READ_BYTE_DATA   |              /* 0x00080000 */
-               !I2C_FUNC_SMBUS_WRITE_BYTE_DATA  |              /* 0x00100000 */
-               !I2C_FUNC_SMBUS_READ_WORD_DATA   |              /* 0x00200000 */
-               !I2C_FUNC_SMBUS_WRITE_WORD_DATA  |              /* 0x00400000 */
-               !I2C_FUNC_SMBUS_PROC_CALL        |              /* 0x00800000 */
-               !I2C_FUNC_SMBUS_READ_BLOCK_DATA  |              /* 0x01000000 */
-               !I2C_FUNC_SMBUS_WRITE_BLOCK_DATA |              /* 0x02000000 */
-               ((priv->features & FEATURE_I2C_BLOCK_READ) ?
-                       I2C_FUNC_SMBUS_READ_I2C_BLOCK : 0) |    /* 0x04000000 */
-               I2C_FUNC_SMBUS_WRITE_I2C_BLOCK   |              /* 0x08000000 */
-
-               I2C_FUNC_SMBUS_BYTE              | /* _READ_BYTE  _WRITE_BYTE */
-               I2C_FUNC_SMBUS_BYTE_DATA         | /* _READ_BYTE_DATA
-                                                   * _WRITE_BYTE_DATA
-                                                   */
-               I2C_FUNC_SMBUS_WORD_DATA         | /* _READ_WORD_DATA
-                                                   * _WRITE_WORD_DATA
-                                                   */
-               I2C_FUNC_SMBUS_BLOCK_DATA        | /* _READ_BLOCK_DATA
-                                                   * _WRITE_BLOCK_DATA
-                                                   */
-               !I2C_FUNC_SMBUS_I2C_BLOCK        | /* _READ_I2C_BLOCK
-                                                   * _WRITE_I2C_BLOCK
-                                                   */
-               !I2C_FUNC_SMBUS_EMUL;              /* _QUICK  _BYTE
+               enable_flag(I2C_FUNC_I2C) | /* 0x00000001(I enabled this one) */
+               disable_flag(I2C_FUNC_10BIT_ADDR)             | /* 0x00000002 */
+               disable_flag(I2C_FUNC_PROTOCOL_MANGLING)      | /* 0x00000004 */
+               enable_flag_if(I2C_FUNC_SMBUS_PEC,
+                              priv->features & FEATURE_SMBUS_PEC) |
+                                                               /* 0x00000008 */
+               disable_flag(I2C_FUNC_SMBUS_BLOCK_PROC_CALL)  | /* 0x00008000 */
+               enable_flag(I2C_FUNC_SMBUS_QUICK)             | /* 0x00010000 */
+               disable_flag(I2C_FUNC_SMBUS_READ_BYTE)        | /* 0x00020000 */
+               disable_flag(I2C_FUNC_SMBUS_WRITE_BYTE)       | /* 0x00040000 */
+               disable_flag(I2C_FUNC_SMBUS_READ_BYTE_DATA)   | /* 0x00080000 */
+               disable_flag(I2C_FUNC_SMBUS_WRITE_BYTE_DATA)  | /* 0x00100000 */
+               disable_flag(I2C_FUNC_SMBUS_READ_WORD_DATA)   | /* 0x00200000 */
+               disable_flag(I2C_FUNC_SMBUS_WRITE_WORD_DATA)  | /* 0x00400000 */
+               disable_flag(I2C_FUNC_SMBUS_PROC_CALL)        | /* 0x00800000 */
+               disable_flag(I2C_FUNC_SMBUS_READ_BLOCK_DATA)  | /* 0x01000000 */
+               disable_flag(I2C_FUNC_SMBUS_WRITE_BLOCK_DATA) | /* 0x02000000 */
+               enable_flag_if(I2C_FUNC_SMBUS_READ_I2C_BLOCK,
+                              priv->features & FEATURE_I2C_BLOCK_READ) |
+                                                               /* 0x04000000 */
+               enable_flag(I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)   | /* 0x08000000 */
+
+               enable_flag(I2C_FUNC_SMBUS_BYTE) | /* _READ_BYTE  _WRITE_BYTE */
+               enable_flag(I2C_FUNC_SMBUS_BYTE_DATA)  | /* _READ_BYTE_DATA
+                                                         * _WRITE_BYTE_DATA
+                                                         */
+               enable_flag(I2C_FUNC_SMBUS_WORD_DATA)  | /* _READ_WORD_DATA
+                                                         * _WRITE_WORD_DATA
+                                                         */
+               enable_flag(I2C_FUNC_SMBUS_BLOCK_DATA) | /* _READ_BLOCK_DATA
+                                                         * _WRITE_BLOCK_DATA
+                                                         */
+               disable_flag(I2C_FUNC_SMBUS_I2C_BLOCK) | /* _READ_I2C_BLOCK
+                                                         * _WRITE_I2C_BLOCK
+                                                         */
+               disable_flag(I2C_FUNC_SMBUS_EMUL); /* _QUICK  _BYTE
                                                    * _BYTE_DATA  _WORD_DATA
                                                    * _PROC_CALL
                                                    * _WRITE_BLOCK_DATA
        return f;
 }
 
+#undef enable_flag
+#undef disable_flag
+#undef enable_flag_if
+
 static const struct i2c_algorithm smbus_algorithm = {
        .smbus_xfer     = i801_access,
        .functionality  = i801_func,