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54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
86 lines
2.1 KiB
ReStructuredText
86 lines
2.1 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
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.. document under the terms of the GNU Free Documentation License,
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.. Version 1.1 or any later version published by the Free Software
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.. Foundation, with no Invariant Sections, no Front-Cover Texts
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.. and no Back-Cover Texts. A copy of the license is included at
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.. Documentation/userspace-api/media/fdl-appendix.rst.
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _cec-func-open:
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**********
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cec open()
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**********
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Name
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====
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cec-open - Open a cec device
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Synopsis
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========
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.. code-block:: c
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#include <fcntl.h>
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.. c:function:: int open( const char *device_name, int flags )
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:name: cec-open
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Arguments
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=========
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``device_name``
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Device to be opened.
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``flags``
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Open flags. Access mode must be ``O_RDWR``.
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When the ``O_NONBLOCK`` flag is given, the
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:ref:`CEC_RECEIVE <CEC_RECEIVE>` and :ref:`CEC_DQEVENT <CEC_DQEVENT>` ioctls
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will return the ``EAGAIN`` error code when no message or event is available, and
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ioctls :ref:`CEC_TRANSMIT <CEC_TRANSMIT>`,
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:ref:`CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` and
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:ref:`CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
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all return 0.
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Other flags have no effect.
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Description
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===========
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To open a cec device applications call :c:func:`open() <cec-open>` with the
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desired device name. The function has no side effects; the device
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configuration remain unchanged.
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When the device is opened in read-only mode, attempts to modify its
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configuration will result in an error, and ``errno`` will be set to
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EBADF.
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Return Value
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============
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:c:func:`open() <cec-open>` returns the new file descriptor on success. On error,
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-1 is returned, and ``errno`` is set appropriately. Possible error codes
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include:
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``EACCES``
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The requested access to the file is not allowed.
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``EMFILE``
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The process already has the maximum number of files open.
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``ENFILE``
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The system limit on the total number of open files has been reached.
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``ENOMEM``
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Insufficient kernel memory was available.
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``ENXIO``
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No device corresponding to this device special file exists.
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