summaryrefslogtreecommitdiff
path: root/Documentation/media/uapi/rc/lirc-dev-intro.rst
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/media/uapi/rc/lirc-dev-intro.rst')
-rw-r--r--Documentation/media/uapi/rc/lirc-dev-intro.rst62
1 files changed, 62 insertions, 0 deletions
diff --git a/Documentation/media/uapi/rc/lirc-dev-intro.rst b/Documentation/media/uapi/rc/lirc-dev-intro.rst
new file mode 100644
index 000000000000..ef97e40f2fd8
--- /dev/null
+++ b/Documentation/media/uapi/rc/lirc-dev-intro.rst
@@ -0,0 +1,62 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _lirc_dev_intro:
+
+************
+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.
+
+Example dmesg output upon a driver registering w/LIRC:
+
+.. code-block:: none
+
+ $ dmesg |grep lirc_dev
+ lirc_dev: IR Remote Control driver registered, major 248
+ rc rc0: lirc_dev: driver ir-lirc-codec (mceusb) registered at minor = 0
+
+What you should see for a chardev:
+
+.. code-block:: none
+
+ $ ls -l /dev/lirc*
+ crw-rw---- 1 root root 248, 0 Jul 2 22:20 /dev/lirc0
+
+**********
+LIRC modes
+**********
+
+LIRC supports some modes of receiving and sending IR codes, as shown
+on the following table.
+
+.. _lirc-mode-mode2:
+
+``LIRC_MODE_MODE2``
+
+ The driver returns a sequence of pulse and space codes to userspace.
+
+ This mode is used only for IR receive.
+
+.. _lirc-mode-lirccode:
+
+``LIRC_MODE_LIRCCODE``
+
+ The IR signal is decoded internally by the receiver. The LIRC interface
+ returns the scancode as an integer value. This is the usual mode used
+ by several TV media cards.
+
+ This mode is used only for IR receive.
+
+.. _lirc-mode-pulse:
+
+``LIRC_MODE_PULSE``
+
+ On puse mode, a sequence of pulse/space integer values are written to the
+ lirc device using :Ref:`lirc-write`.
+
+ This mode is used only for IR send.