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, 72 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/dvb/fe-read-status.rst b/Documentation/userspace-api/media/dvb/fe-read-status.rst
new file mode 100644
index 000000000000..cf781d463a20
--- /dev/null
+++ b/Documentation/userspace-api/media/dvb/fe-read-status.rst
@@ -0,0 +1,72 @@
+.. 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
+
+.. _FE_READ_STATUS:
+
+********************
+ioctl FE_READ_STATUS
+********************
+
+Name
+====
+
+FE_READ_STATUS - Returns status information about the front-end. This call only requires - read-only access to the device
+
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, FE_READ_STATUS, unsigned int *status )
+    :name: FE_READ_STATUS
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <frontend_f_open>`.
+
+``status``
+    pointer to a bitmask integer filled with the values defined by enum
+    :c:type:`fe_status`.
+
+
+Description
+===========
+
+All Digital TV frontend devices support the ``FE_READ_STATUS`` ioctl. It is
+used to check about the locking status of the frontend after being
+tuned. The ioctl takes a pointer to an integer where the status will be
+written.
+
+.. note::
+
+   The size of status is actually sizeof(enum fe_status), with
+   varies according with the architecture. This needs to be fixed in the
+   future.
+
+
+int fe_status
+=============
+
+The fe_status parameter is used to indicate the current state and/or
+state changes of the frontend hardware. It is produced using the enum
+:c:type:`fe_status` values on a bitmask
+
+
+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.