regmap: Provide device read and write map interface for merging

Add the externally visible interface introduced by Lars-Peter's commit
6f3064 (regmap: Add support for device specific write and read flag
masks) separately in order to allow merge into other subsystems for
integration with drivers.  Drivers relying on this feature will not be
functional until they are merged with the implementation.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

include/linux/regmap.h

@@ -53,6 +53,12 @@ struct reg_default {
  * @reg_defaults: Power on reset values for registers (for use with
  *                register cache support).
  * @num_reg_defaults: Number of elements in reg_defaults.
+ *
+ * @read_flag_mask: Mask to be set in the top byte of the register when doing
+ *                  a read.
+ * @write_flag_mask: Mask to be set in the top byte of the register when doing
+ *                   a write. If both read_flag_mask and write_flag_mask are
+ *                   empty the regmap_bus default masks are used.
  */
 struct regmap_config {
 	int reg_bits;
@@ -66,6 +72,9 @@ struct regmap_config {
 	unsigned int max_register;
 	struct reg_default *reg_defaults;
 	int num_reg_defaults;
+
+	u8 read_flag_mask;
+	u8 write_flag_mask;
 };
 
 typedef int (*regmap_hw_write)(struct device *dev, const void *data,