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[media] DocBook: Software Defined Radio Interface 

Document V4L2 SDR interface.

Cc: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Antti Palosaari 2013-12-20 01:50:38 -03:00 committed by Mauro Carvalho Chehab
parent 70b5efb8b7
commit 559f40fe0c
7 changed files with 142 additions and 0 deletions
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10
Documentation/DocBook/media/v4l/compat.xml
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@ -2535,6 +2535,16 @@ fields changed from _s32 to _u32.
</orderedlist> </orderedlist>
</section> </section>
<section>
<title>V4L2 in Linux 3.15</title>
<orderedlist>
<listitem>
<para>Added Software Defined Radio (SDR) Interface.
</para>
</listitem>
</orderedlist>
</section>
<section id="other"> <section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title> <title>Relation of V4L2 to other Linux multimedia APIs</title>

104
Documentation/DocBook/media/v4l/dev-sdr.xml Normal file
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@ -0,0 +1,104 @@
<title>Software Defined Radio Interface (SDR)</title>
<para>
SDR is an abbreviation of Software Defined Radio, the radio device
which uses application software for modulation or demodulation. This interface
is intended for controlling and data streaming of such devices.
</para>
<para>
SDR devices are accessed through character device special files named
<filename>/dev/swradio0</filename> to <filename>/dev/swradio255</filename>
with major number 81 and dynamically allocated minor numbers 0 to 255.
</para>
<section>
<title>Querying Capabilities</title>
<para>
Devices supporting the SDR receiver interface set the
<constant>V4L2_CAP_SDR_CAPTURE</constant> and
<constant>V4L2_CAP_TUNER</constant> flag in the
<structfield>capabilities</structfield> field of &v4l2-capability;
returned by the &VIDIOC-QUERYCAP; ioctl. That flag means the device has an
Analog to Digital Converter (ADC), which is a mandatory element for the SDR receiver.
At least one of the read/write, streaming or asynchronous I/O methods must
be supported.
</para>
</section>
<section>
<title>Supplemental Functions</title>
<para>
SDR devices can support <link linkend="control">controls</link>, and must
support the <link linkend="tuner">tuner</link> ioctls. Tuner ioctls are used
for setting the ADC sampling rate (sampling frequency) and the possible RF tuner
frequency.
</para>
<para>
The <constant>V4L2_TUNER_ADC</constant> tuner type is used for ADC tuners, and
the <constant>V4L2_TUNER_RF</constant> tuner type is used for RF tuners. The
tuner index of the RF tuner (if any) must always follow the ADC tuner index.
Normally the ADC tuner is #0 and the RF tuner is #1.
</para>
<para>
The &VIDIOC-S-HW-FREQ-SEEK; ioctl is not supported.
</para>
</section>
<section>
<title>Data Format Negotiation</title>
<para>
The SDR capture device uses the <link linkend="format">format</link> ioctls to
select the capture format. Both the sampling resolution and the data streaming
format are bound to that selectable format. In addition to the basic
<link linkend="format">format</link> ioctls, the &VIDIOC-ENUM-FMT; ioctl
must be supported as well.
</para>
<para>
To use the <link linkend="format">format</link> ioctls applications set the
<structfield>type</structfield> field of a &v4l2-format; to
<constant>V4L2_BUF_TYPE_SDR_CAPTURE</constant> and use the &v4l2-format-sdr;
<structfield>sdr</structfield> member of the <structfield>fmt</structfield>
union as needed per the desired operation.
Currently only the <structfield>pixelformat</structfield> field of
&v4l2-format-sdr; is used. The content of that field is the V4L2 fourcc code
of the data format.
</para>
<table pgwide="1" frame="none" id="v4l2-format-sdr">
<title>struct <structname>v4l2_format_sdr</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>pixelformat</structfield></entry>
<entry>
The data format or type of compression, set by the application. This is a
little endian <link linkend="v4l2-fourcc">four character code</link>.
V4L2 defines SDR formats in <xref linkend="sdr-formats" />.
</entry>
</row>
<row>
<entry>__u8</entry>
<entry><structfield>reserved[28]</structfield></entry>
<entry>This array is reserved for future extensions.
Drivers and applications must set it to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
An SDR device may support <link linkend="rw">read/write</link>
and/or streaming (<link linkend="mmap">memory mapping</link>
or <link linkend="userp">user pointer</link>) I/O.
</para>
</section>

6
Documentation/DocBook/media/v4l/io.xml
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@ -1005,6 +1005,12 @@ should set this to 0.</entry>
<entry>Buffer for video output overlay (OSD), see <xref <entry>Buffer for video output overlay (OSD), see <xref
linkend="osd" />.</entry> linkend="osd" />.</entry>
</row> </row>
<row>
<entry><constant>V4L2_BUF_TYPE_SDR_CAPTURE</constant></entry>
<entry>11</entry>
<entry>Buffer for Software Defined Radio (SDR), see <xref
linkend="sdr" />.</entry>
</row>
</tbody> </tbody>
</tgroup> </tgroup>
</table> </table>

8
Documentation/DocBook/media/v4l/pixfmt.xml
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@ -811,6 +811,14 @@ extended control <constant>V4L2_CID_MPEG_STREAM_TYPE</constant>, see
</table> </table>
</section> </section>
<section id="sdr-formats">
<title>SDR Formats</title>
<para>These formats are used for <link linkend="sdr">SDR Capture</link>
interface only.</para>
</section>
<section id="pixfmt-reserved"> <section id="pixfmt-reserved">
<title>Reserved Format Identifiers</title> <title>Reserved Format Identifiers</title>

1
Documentation/DocBook/media/v4l/v4l2.xml
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@ -548,6 +548,7 @@ and discussions on the V4L mailing list.</revremark>
<section id="ttx"> &sub-dev-teletext; </section> <section id="ttx"> &sub-dev-teletext; </section>
<section id="radio"> &sub-dev-radio; </section> <section id="radio"> &sub-dev-radio; </section>
<section id="rds"> &sub-dev-rds; </section> <section id="rds"> &sub-dev-rds; </section>
<section id="sdr"> &sub-dev-sdr; </section>
<section id="event"> &sub-dev-event; </section> <section id="event"> &sub-dev-event; </section>
<section id="subdev"> &sub-dev-subdev; </section> <section id="subdev"> &sub-dev-subdev; </section>
</chapter> </chapter>

7
Documentation/DocBook/media/v4l/vidioc-g-fmt.xml
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@ -169,6 +169,13 @@ capture and output devices.</entry>
<entry>Sliced VBI capture or output parameters. See <entry>Sliced VBI capture or output parameters. See
<xref linkend="sliced" /> for details. Used by sliced VBI <xref linkend="sliced" /> for details. Used by sliced VBI
capture and output devices.</entry> capture and output devices.</entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-format-sdr;</entry>
<entry><structfield>sdr</structfield></entry>
<entry>Definition of a data format, see
<xref linkend="pixfmt" />, used by SDR capture devices.</entry>
</row> </row>
<row> <row>
<entry></entry> <entry></entry>

6
Documentation/DocBook/media/v4l/vidioc-querycap.xml
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@ -294,6 +294,12 @@ interface. For more information on audio inputs and outputs see <xref
emit RF-modulated video/audio signals. For more information about emit RF-modulated video/audio signals. For more information about
modulator programming see modulator programming see
<xref linkend="tuner" />.</entry> <xref linkend="tuner" />.</entry>
</row>
<row>
<entry><constant>V4L2_CAP_SDR_CAPTURE</constant></entry>
<entry>0x00100000</entry>
<entry>The device supports the
<link linkend="sdr">SDR Capture</link> interface.</entry>
</row> </row>
<row> <row>
<entry><constant>V4L2_CAP_READWRITE</constant></entry> <entry><constant>V4L2_CAP_READWRITE</constant></entry>