i2c: Restore i2c_smbus_process_call function

Restore the i2c_smbus_process_call() as one driver (for the
Micronas MAP5401) will need it soon.

[JD: Update documentation accordingly.]

Signed-off-by: Prakash Mortha <pmortha@escient.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

3 files changed, 26 insertions, 4 deletions

diff --git a/Documentation/i2c/smbus-protocol b/Documentation/i2c/smbus-protocol
index 24bfb65da17d..9df47441f0e7 100644
--- a/Documentation/i2c/smbus-protocol
+++ b/Documentation/i2c/smbus-protocol
@@ -109,8 +109,8 @@ specified through the Comm byte.
 S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
 
 
-SMBus Process Call
-==================
+SMBus Process Call:  i2c_smbus_process_call()
+=============================================
 
 This command selects a device register (through the Comm byte), sends
 16 bits of data to it, and reads 16 bits of data in return.
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients
index 6b61b3a2e90b..d73ee117a8ca 100644
--- a/Documentation/i2c/writing-clients
+++ b/Documentation/i2c/writing-clients
@@ -606,6 +606,8 @@ SMBus communication
   extern s32 i2c_smbus_read_word_data(struct i2c_client * client, u8 command);
   extern s32 i2c_smbus_write_word_data(struct i2c_client * client,
                                        u8 command, u16 value);
+  extern s32 i2c_smbus_process_call(struct i2c_client *client,
+                                    u8 command, u16 value);
   extern s32 i2c_smbus_read_block_data(struct i2c_client * client,
                                        u8 command, u8 *values);
   extern s32 i2c_smbus_write_block_data(struct i2c_client * client,
@@ -621,8 +623,6 @@ These ones were removed from i2c-core because they had no users, but could
 be added back later if needed:
 
   extern s32 i2c_smbus_write_quick(struct i2c_client * client, u8 value);
-  extern s32 i2c_smbus_process_call(struct i2c_client * client,
-                                    u8 command, u16 value);
   extern s32 i2c_smbus_block_process_call(struct i2c_client *client,
                                           u8 command, u8 length,
                                           u8 *values)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 80ae12048e85..42e852d79ffa 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1688,6 +1688,28 @@ s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
 EXPORT_SYMBOL(i2c_smbus_write_word_data);
 
 /**
+ * i2c_smbus_process_call - SMBus "process call" protocol
+ * @client: Handle to slave device
+ * @command: Byte interpreted by slave
+ * @value: 16-bit "word" being written
+ *
+ * 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)
+{
+        union i2c_smbus_data data;
+        int status;
+        data.word = value;
+
+        status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                                I2C_SMBUS_WRITE, command,
+                                I2C_SMBUS_PROC_CALL, &data);
+        return (status < 0) ? status : data.word;
+}
+EXPORT_SYMBOL(i2c_smbus_process_call);
+
+/**
  * i2c_smbus_read_block_data - SMBus "block read" protocol
  * @client: Handle to slave device
  * @command: Byte interpreted by slave