diff --git a/drivers/mfd/ssbi.c b/drivers/mfd/ssbi.c
index 435c6f7a3b72e3619a6af3bcb9adea74f275f4b3..dd1d28f343f6288584d2498377bdf11c3ab08cf5 100644
--- a/drivers/mfd/ssbi.c
+++ b/drivers/mfd/ssbi.c
@@ -77,7 +77,7 @@ struct ssbi {
 	spinlock_t		lock;
 	enum ssbi_controller_type controller_type;
 	int (*read)(struct ssbi *, u16 addr, u8 *buf, int len);
-	int (*write)(struct ssbi *, u16 addr, u8 *buf, int len);
+	int (*write)(struct ssbi *, u16 addr, const u8 *buf, int len);
 };
 
 #define to_ssbi(dev)	platform_get_drvdata(to_platform_device(dev))
@@ -146,7 +146,7 @@ ssbi_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 }
 
 static int
-ssbi_write_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
+ssbi_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
 {
 	int ret = 0;
 
@@ -223,7 +223,7 @@ ssbi_pa_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 }
 
 static int
-ssbi_pa_write_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
+ssbi_pa_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
 {
 	u32 cmd;
 	int ret = 0;
@@ -255,7 +255,7 @@ int ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
 }
 EXPORT_SYMBOL_GPL(ssbi_read);
 
-int ssbi_write(struct device *dev, u16 addr, u8 *buf, int len)
+int ssbi_write(struct device *dev, u16 addr, const u8 *buf, int len)
 {
 	struct ssbi *ssbi = to_ssbi(dev);
 	unsigned long flags;
diff --git a/include/linux/ssbi.h b/include/linux/ssbi.h
index a92561af60c2531899889c034375cb993a591e0d..bcbb642a7641d936c441e8c2211e9dc287513b6b 100644
--- a/include/linux/ssbi.h
+++ b/include/linux/ssbi.h
@@ -17,7 +17,7 @@
 
 #include <linux/types.h>
 
-int ssbi_write(struct device *dev, u16 addr, u8 *buf, int len);
+int ssbi_write(struct device *dev, u16 addr, const u8 *buf, int len);
 int ssbi_read(struct device *dev, u16 addr, u8 *buf, int len);
 
 #endif