i2c: Constify i2c_client where possible

Helper functions for I2C and SMBus transactions don't modify the
i2c_client that is passed to them, so it can be marked const.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

3 files changed, 37 insertions, 31 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 6b4cc567645b..c7db6980e3a3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1362,7 +1362,7 @@ EXPORT_SYMBOL(i2c_transfer);
  *
  * Returns negative errno, or else the number of bytes written.
  */
-int i2c_master_send(struct i2c_client *client, const char *buf, int count)
+int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
 {
         int ret;
         struct i2c_adapter *adap = client->adapter;
@@ -1389,7 +1389,7 @@ EXPORT_SYMBOL(i2c_master_send);
  *
  * Returns negative errno, or else the number of bytes read.
  */
-int i2c_master_recv(struct i2c_client *client, char *buf, int count)
+int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
 {
         struct i2c_adapter *adap = client->adapter;
         struct i2c_msg msg;
@@ -1679,7 +1679,7 @@ static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
  * This executes the SMBus "receive byte" protocol, returning negative errno
  * else the byte received from the device.
  */
-s32 i2c_smbus_read_byte(struct i2c_client *client)
+s32 i2c_smbus_read_byte(const struct i2c_client *client)
 {
         union i2c_smbus_data data;
         int status;
@@ -1699,7 +1699,7 @@ EXPORT_SYMBOL(i2c_smbus_read_byte);
  * This executes the SMBus "send byte" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
+s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
 {
         return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
                               I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
@@ -1714,7 +1714,7 @@ EXPORT_SYMBOL(i2c_smbus_write_byte);
  * This executes the SMBus "read byte" protocol, returning negative errno
  * else a data byte received from the device.
  */
-s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
+s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
 {
         union i2c_smbus_data data;
         int status;
@@ -1735,7 +1735,8 @@ EXPORT_SYMBOL(i2c_smbus_read_byte_data);
  * This executes the SMBus "write byte" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
+s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
+                              u8 value)
 {
         union i2c_smbus_data data;
         data.byte = value;
@@ -1753,7 +1754,7 @@ EXPORT_SYMBOL(i2c_smbus_write_byte_data);
  * This executes the SMBus "read word" protocol, returning negative errno
  * else a 16-bit unsigned "word" received from the device.
  */
-s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
+s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
 {
         union i2c_smbus_data data;
         int status;
@@ -1774,7 +1775,8 @@ EXPORT_SYMBOL(i2c_smbus_read_word_data);
  * This executes the SMBus "write word" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
+s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
+                              u16 value)
 {
         union i2c_smbus_data data;
         data.word = value;
@@ -1793,7 +1795,8 @@ EXPORT_SYMBOL(i2c_smbus_write_word_data);
  * This executes the SMBus "process call" protocol, returning negative errno
  * else a 16-bit unsigned "word" received from the device.
  */
-s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
+s32 i2c_smbus_process_call(const struct i2c_client *client, u8 command,
+                           u16 value)
 {
         union i2c_smbus_data data;
         int status;
@@ -1821,7 +1824,7 @@ EXPORT_SYMBOL(i2c_smbus_process_call);
  * support this; its emulation through I2C messaging relies on a specific
  * mechanism (I2C_M_RECV_LEN) which may not be implemented.
  */
-s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
                               u8 *values)
 {
         union i2c_smbus_data data;
@@ -1848,7 +1851,7 @@ EXPORT_SYMBOL(i2c_smbus_read_block_data);
  * This executes the SMBus "block write" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
                                u8 length, const u8 *values)
 {
         union i2c_smbus_data data;
@@ -1864,7 +1867,7 @@ s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
 EXPORT_SYMBOL(i2c_smbus_write_block_data);
 
 /* Returns the number of read bytes */
-s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
                                   u8 length, u8 *values)
 {
         union i2c_smbus_data data;
@@ -1884,7 +1887,7 @@ s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
 }
 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
 
-s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
                                    u8 length, const u8 *values)
 {
         union i2c_smbus_data data;
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index d827ce570a8c..0d559b6416dd 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -106,9 +106,9 @@ struct ds1307 {
         struct i2c_client       *client;
         struct rtc_device       *rtc;
         struct work_struct      work;
-        s32 (*read_block_data)(struct i2c_client *client, u8 command,
+        s32 (*read_block_data)(const struct i2c_client *client, u8 command,
                                u8 length, u8 *values);
-        s32 (*write_block_data)(struct i2c_client *client, u8 command,
+        s32 (*write_block_data)(const struct i2c_client *client, u8 command,
                                 u8 length, const u8 *values);
 };
 
@@ -158,8 +158,8 @@ MODULE_DEVICE_TABLE(i2c, ds1307_id);
 
 #define BLOCK_DATA_MAX_TRIES 10
 
-static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
-                                  u8 length, u8 *values)
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+                                       u8 command, u8 length, u8 *values)
 {
         s32 i, data;
 
@@ -172,7 +172,7 @@ static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
         return i;
 }
 
-static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
                                   u8 length, u8 *values)
 {
         u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
@@ -198,7 +198,7 @@ static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
         return length;
 }
 
-static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
                                    u8 length, const u8 *values)
 {
         u8 currvalues[I2C_SMBUS_BLOCK_MAX];
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 56cfe23ffb39..903576df88dc 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -57,9 +57,10 @@ struct i2c_board_info;
  * transmit an arbitrary number of messages without interruption.
  * @count must be be less than 64k since msg.len is u16.
  */
-extern int i2c_master_send(struct i2c_client *client, const char *buf,
+extern int i2c_master_send(const struct i2c_client *client, const char *buf,
+                           int count);
+extern int i2c_master_recv(const struct i2c_client *client, char *buf,
                            int count);
-extern int i2c_master_recv(struct i2c_client *client, char *buf, int count);
 
 /* Transfer num messages.
  */
@@ -78,23 +79,25 @@ extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 /* Now follow the 'nice' access routines. These also document the calling
    conventions of i2c_smbus_xfer. */
 
-extern s32 i2c_smbus_read_byte(struct i2c_client *client);
-extern s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value);
-extern s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command);
-extern s32 i2c_smbus_write_byte_data(struct i2c_client *client,
+extern s32 i2c_smbus_read_byte(const struct i2c_client *client);
+extern s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
+extern s32 i2c_smbus_read_byte_data(const struct i2c_client *client,
+                                    u8 command);
+extern s32 i2c_smbus_write_byte_data(const struct i2c_client *client,
                                      u8 command, u8 value);
-extern s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command);
-extern s32 i2c_smbus_write_word_data(struct i2c_client *client,
+extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
+                                    u8 command);
+extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
                                      u8 command, u16 value);
 /* Returns the number of read bytes */
-extern s32 i2c_smbus_read_block_data(struct i2c_client *client,
+extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
                                      u8 command, u8 *values);
-extern s32 i2c_smbus_write_block_data(struct i2c_client *client,
+extern s32 i2c_smbus_write_block_data(const struct i2c_client *client,
                                       u8 command, u8 length, const u8 *values);
 /* Returns the number of read bytes */
-extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client,
+extern s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client,
                                          u8 command, u8 length, u8 *values);
-extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client,
+extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
                                           u8 command, u8 length,
                                           const u8 *values);
 #endif /* I2C */