diff options
author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/DocBook/media/v4l/dev-sdr.xml | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/DocBook/media/v4l/dev-sdr.xml')
-rw-r--r-- | kernel/Documentation/DocBook/media/v4l/dev-sdr.xml | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/kernel/Documentation/DocBook/media/v4l/dev-sdr.xml b/kernel/Documentation/DocBook/media/v4l/dev-sdr.xml new file mode 100644 index 000000000..f8903568a --- /dev/null +++ b/kernel/Documentation/DocBook/media/v4l/dev-sdr.xml @@ -0,0 +1,120 @@ + <title>Software Defined Radio Interface (SDR)</title> + + <note> + <title>Experimental</title> + <para>This is an <link linkend="experimental"> experimental </link> + interface and may change in the future.</para> + </note> + + <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-sdr-format; +<structfield>sdr</structfield> member of the <structfield>fmt</structfield> +union as needed per the desired operation. +Currently there is two fields, <structfield>pixelformat</structfield> and +<structfield>buffersize</structfield>, of struct &v4l2-sdr-format; which are +used. Content of the <structfield>pixelformat</structfield> is V4L2 FourCC +code of the data format. The <structfield>buffersize</structfield> field is +maximum buffer size in bytes required for data transfer, set by the driver in +order to inform application. + </para> + + <table pgwide="1" frame="none" id="v4l2-sdr-format"> + <title>struct <structname>v4l2_sdr_format</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>__u32</entry> + <entry><structfield>buffersize</structfield></entry> + <entry> +Maximum size in bytes required for data. Value is set by the driver. + </entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>reserved[24]</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> |