[media] i2c: Export an unlocked flavor of i2c_transfer

Some drivers (in particular for TV cards) need exclusive access to
their I2C buses for specific operations. Export an unlocked flavor
of i2c_transfer to give them full control.

The unlocked flavor has the following limitations:
* Obviously, caller must hold the i2c adapter lock.
* No debug messages are logged. We don't want to log messages while
  holding a rt_mutex.
* No check is done on the existence of adap->algo->master_xfer. It
  is thus the caller's responsibility to ensure that the function is
  OK to call.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 195d8b3d9cfb..a121c012309a 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -68,6 +68,9 @@ extern int i2c_master_recv(const struct i2c_client *client, char *buf,
  */
 extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
                         int num);
+/* Unlocked flavor */
+extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+                          int num);
 
 /* This is the very generalized SMBus access routine. You probably do not
    want to use this, though; one of the functions below may be much easier,