diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
index c024a28b057e..d7e3ab41717b 100644
--- a/drivers/mfd/twl-core.c
+++ b/drivers/mfd/twl-core.c
@@ -447,7 +447,7 @@ static struct regmap *twl_get_regmap(u8 mod_no)
  *
  * Returns 0 on success or else a negative error code.
  */
-int twl_i2c_write(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
+int twl_i2c_write(u8 mod_no, const u8 *value, u8 reg, unsigned num_bytes)
 {
 	struct regmap *regmap = twl_get_regmap(mod_no);
 	int ret;
diff --git a/include/linux/mfd/twl.h b/include/linux/mfd/twl.h
index b31e07fa4d51..131451d70960 100644
--- a/include/linux/mfd/twl.h
+++ b/include/linux/mfd/twl.h
@@ -168,7 +168,7 @@ int twl_set_regcache_bypass(u8 mod_no, bool enable);
 /*
  * Read and write several 8-bit registers at once.
  */
-int twl_i2c_write(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes);
+int twl_i2c_write(u8 mod_no, const u8 *value, u8 reg, unsigned num_bytes);
 int twl_i2c_read(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes);
 
 /*
@@ -186,7 +186,7 @@ static inline int twl_i2c_write_u16(u8 mod_no, u16 val, u8 reg) {
 	__le16 value;
 
 	value = cpu_to_le16(val);
-	return twl_i2c_write(mod_no, (u8 *) &value, reg, 2);
+	return twl_i2c_write(mod_no, (const u8 *) &value, reg, 2);
 }
 
 static inline int twl_i2c_read_u16(u8 mod_no, u16 *val, u8 reg) {