regmap: Allow left shifting register offset before access

Drivers can configure it to adjust the final read/write location.
Signed-off-by: NPratyush Yadav <p.yadav@ti.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

drivers/core/regmap.c

@@ -261,8 +261,10 @@ struct regmap *devm_regmap_init(struct udevice *dev,
 		return ERR_PTR(rc);
 
 	map = *mapp;
-	if (config)
+	if (config) {
 		map->width = config->width;
+		map->reg_offset_shift = config->reg_offset_shift;
+	}
 
 	devres_add(dev, mapp);
 	return *mapp;
@@ -349,6 +351,7 @@ int regmap_raw_read_range(struct regmap *map, uint range_num, uint offset,
 	}
 	range = &map->ranges[range_num];
 
+	offset <<= map->reg_offset_shift;
 	if (offset + val_len > range->size) {
 		debug("%s: offset/size combination invalid\n", __func__);
 		return -ERANGE;
@@ -458,6 +461,7 @@ int regmap_raw_write_range(struct regmap *map, uint range_num, uint offset,
 	}
 	range = &map->ranges[range_num];
 
+	offset <<= map->reg_offset_shift;
 	if (offset + val_len > range->size) {
 		debug("%s: offset/size combination invalid\n", __func__);
 		return -ERANGE;

include/regmap.h

@@ -82,9 +82,12 @@ struct regmap_bus;
  *
  * @width:		Width of the read/write operations. Defaults to
  *			REGMAP_SIZE_32 if set to 0.
+ * @reg_offset_shift	Left shift the register offset by this value before
+ *			performing read or write.
  */
 struct regmap_config {
 	enum regmap_size_t width;
+	u32 reg_offset_shift;
 };
 
 /**
@@ -92,12 +95,15 @@ struct regmap_config {
  *
  * @width:		Width of the read/write operations. Defaults to
  *			REGMAP_SIZE_32 if set to 0.
+ * @reg_offset_shift	Left shift the register offset by this value before
+ *			performing read or write.
  * @range_count:	Number of ranges available within the map
  * @ranges:		Array of ranges
  */
 struct regmap {
 	enum regmap_endianness_t endianness;
 	enum regmap_size_t width;
+	u32 reg_offset_shift;
 	int range_count;
 	struct regmap_range ranges[0];
 };