diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/dev-sdr.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/dev-sdr.xml | 126 |
1 files changed, 0 insertions, 126 deletions
diff --git a/Documentation/DocBook/media/v4l/dev-sdr.xml b/Documentation/DocBook/media/v4l/dev-sdr.xml deleted file mode 100644 index 6da1157fb..000000000 --- a/Documentation/DocBook/media/v4l/dev-sdr.xml +++ /dev/null @@ -1,126 +0,0 @@ - <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. - </para> - <para> -Devices supporting the SDR transmitter interface set the -<constant>V4L2_CAP_SDR_OUTPUT</constant> and -<constant>V4L2_CAP_MODULATOR</constant> flag in the -<structfield>capabilities</structfield> field of &v4l2-capability; -returned by the &VIDIOC-QUERYCAP; ioctl. That flag means the device has an -Digital to Analog Converter (DAC), which is a mandatory element for the SDR transmitter. - </para> - <para> -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/DAC sampling rate (sampling frequency) and the possible -radio frequency (RF). - </para> - - <para> -The <constant>V4L2_TUNER_SDR</constant> tuner type is used for setting SDR -device ADC/DAC frequency, and the <constant>V4L2_TUNER_RF</constant> -tuner type is used for setting radio frequency. -The tuner index of the RF tuner (if any) must always follow the SDR tuner index. -Normally the SDR 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 device uses the <link linkend="format">format</link> ioctls to -select the capture and output 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> or -<constant>V4L2_BUF_TYPE_SDR_OUTPUT</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> |