Documentation/media/uapi/rc/lirc-dev-intro.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _lirc_dev_intro:
   4
   5 ************
   6 Introduction
   7 ************
   8
   9 The LIRC device interface is a bi-directional interface for transporting
  10 raw IR data between userspace and kernelspace. Fundamentally, it is just
  11 a chardev (/dev/lircX, for X = 0, 1, 2, ...), with a number of standard
  12 struct file_operations defined on it. With respect to transporting raw
  13 IR data to and fro, the essential fops are read, write and ioctl.
  14
  15 Example dmesg output upon a driver registering w/LIRC:
  16
  17 .. code-block:: none
  18
  19     $ dmesg |grep lirc_dev
  20     lirc_dev: IR Remote Control driver registered, major 248
  21     rc rc0: lirc_dev: driver ir-lirc-codec (mceusb) registered at minor = 0
  22
  23 What you should see for a chardev:
  24
  25 .. code-block:: none
  26
  27     $ ls -l /dev/lirc*
  28     crw-rw---- 1 root root 248, 0 Jul 2 22:20 /dev/lirc0
  29
  30 **********
  31 LIRC modes
  32 **********
  33
  34 LIRC supports some modes of receiving and sending IR codes, as shown
  35 on the following table.
  36
  37 .. _lirc-mode-mode2:
  38
  39 ``LIRC_MODE_MODE2``
  40
  41     The driver returns a sequence of pulse and space codes to userspace.
  42
  43     This mode is used only for IR receive.
  44
  45 .. _lirc-mode-lirccode:
  46
  47 ``LIRC_MODE_LIRCCODE``
  48
  49     The IR signal is decoded internally by the receiver. The LIRC interface
  50     returns the scancode as an integer value. This is the usual mode used
  51     by several TV media cards.
  52
  53     This mode is used only for IR receive.
  54
  55 .. _lirc-mode-pulse:
  56
  57 ``LIRC_MODE_PULSE``
  58
  59     On puse mode, a sequence of pulse/space integer values are written to the
  60     lirc device using :Ref:`lirc-write`.
  61
  62     This mode is used only for IR send.