media: docs: move uAPI book to userspace-api/media

Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee3862 ("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>

1 files changed, 84 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/dvb/ca-fopen.rst b/Documentation/userspace-api/media/dvb/ca-fopen.rst
new file mode 100644
index 000000000000..aa0fde1739a8
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@@ -0,0 +1,84 @@
+.. Permission is granted to copy, distribute and/or modify this
+.. document under the terms of the GNU Free Documentation License,
+.. Version 1.1 or any later version published by the Free Software
+.. Foundation, with no Invariant Sections, no Front-Cover Texts
+.. and no Back-Cover Texts. A copy of the license is included at
+.. Documentation/userspace-api/media/fdl-appendix.rst.
+..
+.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
+
+.. _ca_fopen:
+
+====================
+Digital TV CA open()
+====================
+
+Name
+----
+
+Digital TV CA open()
+
+
+Synopsis
+--------
+
+.. c:function:: int open(const char *name, int flags)
+    :name: dvb-ca-open
+
+
+Arguments
+---------
+
+``name``
+  Name of specific Digital TV CA device.
+
+``flags``
+  A bit-wise OR of the following flags:
+
+.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 1 16
+
+    -  - ``O_RDONLY``
+       - read-only access
+
+    -  - ``O_RDWR``
+       - read/write access
+
+    -  - ``O_NONBLOCK``
+       - open in non-blocking mode
+         (blocking mode is the default)
+
+
+Description
+-----------
+
+This system call opens a named ca device (e.g. ``/dev/dvb/adapter?/ca?``)
+for subsequent use.
+
+When an ``open()`` call has succeeded, the device will be ready for use. The
+significance of blocking or non-blocking mode is described in the
+documentation for functions where there is a difference. It does not
+affect the semantics of the ``open()`` call itself. A device opened in
+blocking mode can later be put into non-blocking mode (and vice versa)
+using the ``F_SETFL`` command of the ``fcntl`` system call. This is a
+standard system call, documented in the Linux manual page for fcntl.
+Only one user can open the CA Device in ``O_RDWR`` mode. All other
+attempts to open the device in this mode will fail, and an error code
+will be returned.
+
+
+Return Value
+------------
+
+
+On success 0 is returned.
+
+On error -1 is returned, and the ``errno`` variable is set
+appropriately.
+
+Generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.