[media] media: Media device information query

Create the following ioctl and implement it at the media device level to
query device information.

- MEDIA_IOC_DEVICE_INFO: Query media device information

The ioctl and its data structure are defined in the new kernel header
linux/media.h available to userspace applications.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/Documentation/DocBook/v4l/media-func-open.xml b/Documentation/DocBook/v4l/media-func-open.xml
new file mode 100644
index 000000000000..f7df034dc9ed
--- /dev/null
+++ b/Documentation/DocBook/v4l/media-func-open.xml
@@ -0,0 +1,94 @@
+<refentry id="media-func-open">
+  <refmeta>
+    <refentrytitle>media open()</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>media-open</refname>
+    <refpurpose>Open a media device</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;fcntl.h&gt;</funcsynopsisinfo>
+      <funcprototype>
+	<funcdef>int <function>open</function></funcdef>
+	<paramdef>const char *<parameter>device_name</parameter></paramdef>
+	<paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>device_name</parameter></term>
+	<listitem>
+	  <para>Device to be opened.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>flags</parameter></term>
+	<listitem>
+	  <para>Open flags. Access mode must be either <constant>O_RDONLY</constant>
+	  or <constant>O_RDWR</constant>. Other flags have no effect.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+  <refsect1>
+    <title>Description</title>
+    <para>To open a media device applications call <function>open()</function>
+    with the desired device name. The function has no side effects; the device
+    configuration remain unchanged.</para>
+    <para>When the device is opened in read-only mode, attemps to modify its
+    configuration will result in an error, and <varname>errno</varname> will be
+    set to <errorcode>EBADF</errorcode>.</para>
+  </refsect1>
+  <refsect1>
+    <title>Return Value</title>
+
+    <para><function>open</function> returns the new file descriptor on success.
+    On error, -1 is returned, and <varname>errno</varname> is set appropriately.
+    Possible error codes are:</para>
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EACCES</errorcode></term>
+	<listitem>
+	  <para>The requested access to the file is not allowed.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EMFILE</errorcode></term>
+	<listitem>
+	  <para>The  process  already  has  the  maximum number of files open.
+	  </para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENFILE</errorcode></term>
+	<listitem>
+	  <para>The system limit on the total number of open files has been
+	  reached.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENOMEM</errorcode></term>
+	<listitem>
+	  <para>Insufficient kernel memory was available.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENXIO</errorcode></term>
+	<listitem>
+	  <para>No device corresponding to this device special file exists.
+	  </para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>