[media] doc-rst: document ioctl LIRC_GET_SEND_MODE

Move the documentation of this ioctl from lirc_ioctl to its
own file, and add a short description about the pulse mode
used by IR TX.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/rc/lirc-get-send-mode.rst

+.. -*- coding: utf-8; mode: rst -*-
+
+.. _lirc_get_send_mode:
+
+************************
+ioctl LIRC_GET_SEND_MODE
+************************
+
+Name
+====
+
+LIRC_GET_SEND_MODE - Get supported transmit mode.
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, __u32 *tx_modes )
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by open().
+
+``request``
+    LIRC_GET_SEND_MODE
+
+``tx_modes``
+    Bitmask with the supported transmit modes.
+
+
+Description
+===========
+
+Get supported transmit mode.
+
+.. _lirc-mode-pulse:
+
+Currently, only ``LIRC_MODE_PULSE`` is supported by lircd on TX. On
+puse mode, a sequence of pulse/space integer values are written to the
+lirc device using ``write()``.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.

Documentation/media/uapi/rc/lirc_device_interface.rst

@@ -13,4 +13,5 @@ LIRC Device Interface
     lirc_read
     lirc_write
     lirc-get-features
+    lirc-get-send-mode
     lirc_ioctl

Documentation/media/uapi/rc/lirc_ioctl.rst

@@ -49,15 +49,6 @@ device can rely on working with the default settings initially.
 I/O control requests
 ====================
 
-
-.. _LIRC_GET_SEND_MODE:
-.. _lirc-mode-pulse:
-
-``LIRC_GET_SEND_MODE``
-
-    Get supported transmit mode. Only ``LIRC_MODE_PULSE`` is supported by
-    lircd.
-
 .. _LIRC_GET_REC_MODE:
 .. _lirc-mode-mode2:
 .. _lirc-mode-lirccode: