Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/rc/lirc-read.rst b/Documentation/userspace-api/media/rc/lirc-read.rst
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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: RC
+
+.. _lirc-read:
+
+***********
+LIRC read()
+***********
+
+Name
+====
+
+lirc-read - Read from a LIRC device
+
+Synopsis
+========
+
+.. code-block:: c
+
+    #include <unistd.h>
+
+.. c:function:: ssize_t read( int fd, void *buf, size_t count )
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by ``open()``.
+
+``buf``
+   Buffer to be filled
+
+``count``
+   Max number of bytes to read
+
+Description
+===========
+
+:c:func:`read()` attempts to read up to ``count`` bytes from file
+descriptor ``fd`` into the buffer starting at ``buf``.  If ``count`` is zero,
+:c:func:`read()` returns zero and has no other results. If ``count``
+is greater than ``SSIZE_MAX``, the result is unspecified.
+
+The exact format of the data depends on what :ref:`lirc_modes` a driver
+uses. Use :ref:`lirc_get_features` to get the supported mode, and use
+:ref:`lirc_set_rec_mode` set the current active mode.
+
+The mode :ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>` is for raw IR,
+in which packets containing an unsigned int value describing an IR signal are
+read from the chardev.
+
+Alternatively, :ref:`LIRC_MODE_SCANCODE <lirc-mode-scancode>` can be available,
+in this mode scancodes which are either decoded by software decoders, or
+by hardware decoders. The :c:type:`rc_proto` member is set to the
+:ref:`IR protocol <Remote_controllers_Protocols>`
+used for transmission, and ``scancode`` to the decoded scancode,
+and the ``keycode`` set to the keycode or ``KEY_RESERVED``.
+
+Return Value
+============
+
+On success, the number of bytes read is returned. It is not an error if
+this number is smaller than the number of bytes requested, or the amount
+of data required for one frame.  On error, -1 is returned, and the ``errno``
+variable is set appropriately.