regmap: Introduce regmap_get_max_register

This patch introduces regmap_get_max_register() function which would be
used by the infrastructures like nvmem framework built on top of
regmap.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 116655d..2d87ded 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -433,6 +433,7 @@
 				   unsigned int mask, unsigned int val,
 				   bool *change);
 int regmap_get_val_bytes(struct regmap *map);
+int regmap_get_max_register(struct regmap *map);
 int regmap_async_complete(struct regmap *map);
 bool regmap_can_raw_write(struct regmap *map);
 
@@ -676,6 +677,12 @@
 	return -EINVAL;
 }
 
+static inline int regmap_get_max_register(struct regmap *map)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regcache_sync(struct regmap *map)
 {
 	WARN_ONCE(1, "regmap API is disabled");