From 7d402db89b5b6d3ca5128937dc04653df8668978 Mon Sep 17 00:00:00 2001 From: Sean Young Date: Sat, 25 Feb 2017 06:51:34 -0500 Subject: media: lirc: document LIRC_MODE_SCANCODE Lirc supports a new mode which requires documentation. Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/rc/lirc-dev-intro.rst | 51 +++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 5 deletions(-) (limited to 'Documentation/media/uapi/rc/lirc-dev-intro.rst') diff --git a/Documentation/media/uapi/rc/lirc-dev-intro.rst b/Documentation/media/uapi/rc/lirc-dev-intro.rst index a3fa3c1ef169..47c6c218e72a 100644 --- a/Documentation/media/uapi/rc/lirc-dev-intro.rst +++ b/Documentation/media/uapi/rc/lirc-dev-intro.rst @@ -6,11 +6,12 @@ Introduction ************ -The LIRC device interface is a bi-directional interface for transporting -raw IR data between userspace and kernelspace. Fundamentally, it is just -a chardev (/dev/lircX, for X = 0, 1, 2, ...), with a number of standard -struct file_operations defined on it. With respect to transporting raw -IR data to and fro, the essential fops are read, write and ioctl. +LIRC stands for Linux Infrared Remote Control. The LIRC device interface is +a bi-directional interface for transporting raw IR and decoded scancodes +data between userspace and kernelspace. Fundamentally, it is just a chardev +(/dev/lircX, for X = 0, 1, 2, ...), with a number of standard struct +file_operations defined on it. With respect to transporting raw IR and +decoded scancodes to and fro, the essential fops are read, write and ioctl. Example dmesg output upon a driver registering w/LIRC: @@ -36,6 +37,46 @@ LIRC modes LIRC supports some modes of receiving and sending IR codes, as shown on the following table. +.. _lirc-mode-scancode: +.. _lirc-scancode-flag-toggle: +.. _lirc-scancode-flag-repeat: + +``LIRC_MODE_SCANCODE`` + + This mode is for both sending and receiving IR. + + For transmitting (aka sending), create a ``struct lirc_scancode`` with + the desired scancode set in the ``scancode`` member, ``rc_proto`` set + the IR protocol, and all other members set to 0. Write this struct to + the lirc device. + + For receiving, you read ``struct lirc_scancode`` from the lirc device, + with ``scancode`` set to the received scancode and the IR protocol + ``rc_proto``. If the scancode maps to a valid key code, this is set + in the ``keycode`` field, else it is set to ``KEY_RESERVED``. + + The ``flags`` can have ``LIRC_SCANCODE_FLAG_TOGGLE`` set if the toggle + bit is set in protocols that support it (e.g. rc-5 and rc-6), or + ``LIRC_SCANCODE_FLAG_REPEAT`` for when a repeat is received for protocols + that support it (e.g. nec). + + In the Sanyo and NEC protocol, if you hold a button on remote, rather than + repeating the entire scancode, the remote sends a shorter message with + no scancode, which just means button is held, a "repeat". When this is + received, the ``LIRC_SCANCODE_FLAG_REPEAT`` is set and the scancode and + keycode is repeated. + + With nec, there is no way to distinguish "button hold" from "repeatedly + pressing the same button". The rc-5 and rc-6 protocols have a toggle bit. + When a button is released and pressed again, the toggle bit is inverted. + If the toggle bit is set, the ``LIRC_SCANCODE_FLAG_TOGGLE`` is set. + + The ``timestamp`` field is filled with the time nanoseconds + (in ``CLOCK_MONOTONIC``) when the scancode was decoded. + + An ``enum rc_proto`` in the :ref:`lirc_header` lists all the supported + IR protocols. + .. _lirc-mode-mode2: ``LIRC_MODE_MODE2`` -- cgit