soundwire: bus: Make sdw_nwrite() data pointer argument const

Idiomatically, write functions should take const pointers to the
data buffer, as they don't change the data. They are also likely
to be called from functions that receive a const data pointer.

Internally the pointer is passed to function/structs shared with
the read functions, requiring a cast, but this is an implementation
detail that should be hidden by the public API.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210616145901.29402-1-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 85bcf60f9697062cbacf6a74d56e1563c55635ab..adcbf3969110ee44fdbcb8ec22fbcb0dd4c44f4c 100644 (file)
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -394,13 +394,13 @@ sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 }
 
 static int
-sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
+sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
        struct sdw_msg msg;
        int ret;
 
        ret = sdw_fill_msg(&msg, slave, addr, count,
-                          slave->dev_num, SDW_MSG_FLAG_WRITE, val);
+                          slave->dev_num, SDW_MSG_FLAG_WRITE, (u8 *)val);
        if (ret < 0)
                return ret;
 
@@ -535,9 +535,9 @@ EXPORT_SYMBOL(sdw_nread);
  * @slave: SDW Slave
  * @addr: Register address
  * @count: length
- * @val: Buffer for values to be read
+ * @val: Buffer for values to be written
  */
-int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
+int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
        int ret;
 

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 8ca736e92d5af53bb4445dcb3440374555df398e..ddbeb00799e41d9905120ed7670d9589c98a8b9e 100644 (file)
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -1039,7 +1039,7 @@ int sdw_write(struct sdw_slave *slave, u32 addr, u8 value);
 int sdw_write_no_pm(struct sdw_slave *slave, u32 addr, u8 value);
 int sdw_read_no_pm(struct sdw_slave *slave, u32 addr);
 int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val);
-int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val);
+int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val);
 int sdw_compare_devid(struct sdw_slave *slave, struct sdw_slave_id id);
 void sdw_extract_slave_id(struct sdw_bus *bus, u64 addr, struct sdw_slave_id *id);