V4L/DVB (12761): DocBook: add media API specs

The V4L and DVB API's are there for a long time. however, up to now,
no efforts were done to merge them to kernel DocBook.

This patch adds the current versions of the specs as an unique compendium.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 168 insertions, 0 deletions

diff --git a/Documentation/DocBook/v4l/dev-rds.xml b/Documentation/DocBook/v4l/dev-rds.xml
new file mode 100644
index 000000000000..0869d701b1e5
--- /dev/null
+++ b/Documentation/DocBook/v4l/dev-rds.xml
@@ -0,0 +1,168 @@
+     <title>RDS Interface</title>
+
+      <para>The Radio Data System transmits supplementary
+information in binary format, for example the station name or travel
+information, on an inaudible audio subcarrier of a radio program. This
+interface is aimed at devices capable of receiving and decoding RDS
+information.</para>
+
+      <para>For more information see the core RDS standard <xref linkend="en50067" />
+and the RBDS standard <xref linkend="nrsc4" />.</para>
+
+      <para>Note that the RBDS standard as is used in the USA is almost identical
+to the RDS standard. Any RDS decoder can also handle RBDS. Only some of the fields
+have slightly different meanings. See the RBDS standard for more information.</para>
+
+      <para>The RBDS standard also specifies support for MMBS (Modified Mobile Search).
+This is a proprietary format which seems to be discontinued. The RDS interface does not
+support this format. Should support for MMBS (or the so-called 'E blocks' in general)
+be needed, then please contact the linux-media mailing list: &v4l-ml;.</para>
+
+  <section>
+    <title>Querying Capabilities</title>
+
+    <para>Devices supporting the RDS capturing API
+set the <constant>V4L2_CAP_RDS_CAPTURE</constant> flag in
+the <structfield>capabilities</structfield> field of &v4l2-capability;
+returned by the &VIDIOC-QUERYCAP; ioctl.
+Any tuner that supports RDS will set the
+<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield>
+field of &v4l2-tuner;.
+Whether an RDS signal is present can be detected by looking at
+the <structfield>rxsubchans</structfield> field of &v4l2-tuner;: the
+<constant>V4L2_TUNER_SUB_RDS</constant> will be set if RDS data was detected.</para>
+
+    <para>Devices supporting the RDS output API
+set the <constant>V4L2_CAP_RDS_OUTPUT</constant> flag in
+the <structfield>capabilities</structfield> field of &v4l2-capability;
+returned by the &VIDIOC-QUERYCAP; ioctl.
+Any modulator that supports RDS will set the
+<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield>
+field of &v4l2-modulator;.
+In order to enable the RDS transmission one must set the <constant>V4L2_TUNER_SUB_RDS</constant>
+bit in the <structfield>txsubchans</structfield> field of &v4l2-modulator;.</para>
+
+  </section>
+
+  <section>
+    <title>Reading RDS data</title>
+
+      <para>RDS data can be read from the radio device
+with the &func-read; function. The data is packed in groups of three bytes,
+as follows:</para>
+    <table frame="none" pgwide="1" id="v4l2-rds-data">
+      <title>struct
+<structname>v4l2_rds_data</structname></title>
+      <tgroup cols="3">
+        <colspec colname="c1" colwidth="1*" />
+        <colspec colname="c2" colwidth="1*" />
+        <colspec colname="c3" colwidth="5*" />
+        <tbody valign="top">
+          <row>
+            <entry>__u8</entry>
+            <entry><structfield>lsb</structfield></entry>
+            <entry>Least Significant Byte of RDS Block</entry>
+          </row>
+          <row>
+            <entry>__u8</entry>
+            <entry><structfield>msb</structfield></entry>
+            <entry>Most Significant Byte of RDS Block</entry>
+          </row>
+          <row>
+            <entry>__u8</entry>
+            <entry><structfield>block</structfield></entry>
+            <entry>Block description</entry>
+          </row>
+        </tbody>
+      </tgroup>
+    </table>
+    <table frame="none" pgwide="1" id="v4l2-rds-block">
+      <title>Block description</title>
+      <tgroup cols="2">
+        <colspec colname="c1" colwidth="1*" />
+        <colspec colname="c2" colwidth="5*" />
+        <tbody valign="top">
+          <row>
+            <entry>Bits 0-2</entry>
+            <entry>Block (aka offset) of the received data.</entry>
+          </row>
+          <row>
+            <entry>Bits 3-5</entry>
+            <entry>Deprecated. Currently identical to bits 0-2. Do not use these bits.</entry>
+          </row>
+          <row>
+            <entry>Bit 6</entry>
+            <entry>Corrected bit. Indicates that an error was corrected for this data block.</entry>
+          </row>
+          <row>
+            <entry>Bit 7</entry>
+            <entry>Error bit. Indicates that an uncorrectable error occurred during reception of this block.</entry>
+          </row>
+        </tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="v4l2-rds-block-codes">
+      <title>Block defines</title>
+      <tgroup cols="3">
+        <colspec colname="c1" colwidth="1*" />
+        <colspec colname="c2" colwidth="1*" />
+        <colspec colname="c3" colwidth="5*" />
+        <tbody valign="top">
+          <row>
+            <entry>V4L2_RDS_BLOCK_MSK</entry>
+            <entry>7</entry>
+            <entry>Mask for bits 0-2 to get the block ID.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_A</entry>
+            <entry>0</entry>
+            <entry>Block A.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_B</entry>
+            <entry>1</entry>
+            <entry>Block B.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_C</entry>
+            <entry>2</entry>
+            <entry>Block C.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_D</entry>
+            <entry>3</entry>
+            <entry>Block D.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_C_ALT</entry>
+            <entry>4</entry>
+            <entry>Block C'.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_INVALID</entry>
+            <entry>7</entry>
+            <entry>An invalid block.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_CORRECTED</entry>
+            <entry>0x40</entry>
+            <entry>A bit error was detected but corrected.</entry>
+          </row>
+          <row>
+            <entry>V4L2_RDS_BLOCK_ERROR</entry>
+            <entry>0x80</entry>
+            <entry>An incorrectable error occurred.</entry>
+          </row>
+        </tbody>
+      </tgroup>
+    </table>
+  </section>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+ -->