Based on kernel version 4.7.2. Page generated on 2016-08-22 22:44 EST.
1 <title>DVB Frontend API</title> 2 3 <para>The DVB frontend API was designed to support three types of delivery systems:</para> 4 <itemizedlist> 5 <listitem><para>Terrestrial systems: DVB-T, DVB-T2, ATSC, ATSC M/H, ISDB-T, DVB-H, DTMB, CMMB</para></listitem> 6 <listitem><para>Cable systems: DVB-C Annex A/C, ClearQAM (DVB-C Annex B), ISDB-C</para></listitem> 7 <listitem><para>Satellite systems: DVB-S, DVB-S2, DVB Turbo, ISDB-S, DSS</para></listitem> 8 </itemizedlist> 9 <para>The DVB frontend controls several sub-devices including:</para> 10 <itemizedlist> 11 <listitem><para>Tuner</para></listitem> 12 <listitem><para>Digital TV demodulator</para></listitem> 13 <listitem><para>Low noise amplifier (LNA)</para></listitem> 14 <listitem><para>Satellite Equipment Control (SEC) hardware (only for Satellite).</para></listitem> 15 </itemizedlist> 16 <para>The frontend can be accessed through 17 <constant>/dev/dvb/adapter?/frontend?</constant>. Data types and 18 ioctl definitions can be accessed by including 19 <constant>linux/dvb/frontend.h</constant> in your application. 20 </para> 21 22 <para>NOTE: Transmission via the internet (DVB-IP) 23 is not yet handled by this API but a future extension is possible.</para> 24 <para>On Satellite systems, the API support for the Satellite Equipment Control 25 (SEC) allows to power control and to send/receive signals to control the 26 antenna subsystem, selecting the polarization and choosing the Intermediate 27 Frequency IF) of the Low Noise Block Converter Feed Horn (LNBf). It 28 supports the DiSEqC and V-SEC protocols. The DiSEqC (digital SEC) 29 specification is available at 30 <ulink url="http://www.eutelsat.com/satellites/4_5_5.html">Eutelsat</ulink>.</para> 31 32 <section id="query-dvb-frontend-info"> 33 <title>Querying frontend information</title> 34 35 <para>Usually, the first thing to do when the frontend is opened is to 36 check the frontend capabilities. This is done using <link linkend="FE_GET_INFO">FE_GET_INFO</link>. This ioctl will enumerate 37 the DVB API version and other characteristics about the frontend, and 38 can be opened either in read only or read/write mode.</para> 39 </section> 40 41 <section id="dvb-fe-read-status"> 42 <title>Querying frontend status and statistics</title> 43 44 <para>Once <link linkend="FE_GET_PROPERTY"><constant>FE_SET_PROPERTY</constant></link> 45 is called, the frontend will run a kernel thread that will periodically 46 check for the tuner lock status and provide statistics about the quality 47 of the signal.</para> 48 <para>The information about the frontend tuner locking status can be queried 49 using <link linkend="FE_READ_STATUS">FE_READ_STATUS</link>.</para> 50 <para>Signal statistics are provided via <link linkend="FE_GET_PROPERTY"><constant>FE_GET_PROPERTY</constant></link>. 51 Please note that several statistics require the demodulator to be fully 52 locked (e. g. with FE_HAS_LOCK bit set). See 53 <link linkend="frontend-stat-properties">Frontend statistics indicators</link> 54 for more details.</para> 55 </section> 56 57 &sub-dvbproperty; 58 59 <section id="frontend_fcalls"> 60 <title>Frontend Function Calls</title> 61 62 <refentry id="frontend_f_open"> 63 <refmeta> 64 <refentrytitle>DVB frontend open()</refentrytitle> 65 &manvol; 66 </refmeta> 67 68 <refnamediv> 69 <refname>fe-open</refname> 70 <refpurpose>Open a frontend device</refpurpose> 71 </refnamediv> 72 73 <refsynopsisdiv> 74 <funcsynopsis> 75 <funcsynopsisinfo>#include <fcntl.h></funcsynopsisinfo> 76 <funcprototype> 77 <funcdef>int <function>open</function></funcdef> 78 <paramdef>const char *<parameter>device_name</parameter></paramdef> 79 <paramdef>int <parameter>flags</parameter></paramdef> 80 </funcprototype> 81 </funcsynopsis> 82 </refsynopsisdiv> 83 84 <refsect1> 85 <title>Arguments</title> 86 87 <variablelist> 88 <varlistentry> 89 <term><parameter>device_name</parameter></term> 90 <listitem> 91 <para>Device to be opened.</para> 92 </listitem> 93 </varlistentry> 94 <varlistentry> 95 <term><parameter>flags</parameter></term> 96 <listitem> 97 <para>Open flags. Access can either be 98 <constant>O_RDWR</constant> or <constant>O_RDONLY</constant>.</para> 99 <para>Multiple opens are allowed with <constant>O_RDONLY</constant>. In this mode, only query and read ioctls are allowed.</para> 100 <para>Only one open is allowed in <constant>O_RDWR</constant>. In this mode, all ioctls are allowed.</para> 101 <para>When the <constant>O_NONBLOCK</constant> flag is given, the system calls may return &EAGAIN; when no data is available or when the device driver is temporarily busy.</para> 102 <para>Other flags have no effect.</para> 103 </listitem> 104 </varlistentry> 105 </variablelist> 106 </refsect1> 107 <refsect1> 108 <title>Description</title> 109 <para>This system call opens a named frontend device (<constant>/dev/dvb/adapter?/frontend?</constant>) 110 for subsequent use. Usually the first thing to do after a successful open is to 111 find out the frontend type with <link linkend="FE_GET_INFO">FE_GET_INFO</link>.</para> 112 <para>The device can be opened in read-only mode, which only allows monitoring of 113 device status and statistics, or read/write mode, which allows any kind of use 114 (e.g. performing tuning operations.) 115 </para> 116 <para>In a system with multiple front-ends, it is usually the case that multiple devices 117 cannot be open in read/write mode simultaneously. As long as a front-end 118 device is opened in read/write mode, other open() calls in read/write mode will 119 either fail or block, depending on whether non-blocking or blocking mode was 120 specified. A front-end device opened in blocking mode can later be put into 121 non-blocking mode (and vice versa) using the F_SETFL command of the fcntl 122 system call. This is a standard system call, documented in the Linux manual 123 page for fcntl. When an open() call has succeeded, the device will be ready 124 for use in the specified mode. This implies that the corresponding hardware is 125 powered up, and that other front-ends may have been powered down to make 126 that possible.</para> 127 </refsect1> 128 129 <refsect1> 130 <title>Return Value</title> 131 132 <para>On success <function>open</function> returns the new file 133 descriptor. On error -1 is returned, and the <varname>errno</varname> 134 variable is set appropriately. Possible error codes are:</para> 135 136 <variablelist> 137 <varlistentry> 138 <term><errorcode>EACCES</errorcode></term> 139 <listitem> 140 <para>The caller has no permission to access the 141 device.</para> 142 </listitem> 143 </varlistentry> 144 <varlistentry> 145 <term><errorcode>EBUSY</errorcode></term> 146 <listitem> 147 <para>The the device driver is already in use.</para> 148 </listitem> 149 </varlistentry> 150 <varlistentry> 151 <term><errorcode>ENXIO</errorcode></term> 152 <listitem> 153 <para>No device corresponding to this device special file 154 exists.</para> 155 </listitem> 156 </varlistentry> 157 <varlistentry> 158 <term><errorcode>ENOMEM</errorcode></term> 159 <listitem> 160 <para>Not enough kernel memory was available to complete the 161 request.</para> 162 </listitem> 163 </varlistentry> 164 <varlistentry> 165 <term><errorcode>EMFILE</errorcode></term> 166 <listitem> 167 <para>The process already has the maximum number of 168 files open.</para> 169 </listitem> 170 </varlistentry> 171 <varlistentry> 172 <term><errorcode>ENFILE</errorcode></term> 173 <listitem> 174 <para>The limit on the total number of files open on the 175 system has been reached.</para> 176 </listitem> 177 </varlistentry> 178 <varlistentry> 179 <term><errorcode>ENODEV</errorcode></term> 180 <listitem> 181 <para>The device got removed.</para> 182 </listitem> 183 </varlistentry> 184 </variablelist> 185 </refsect1> 186 </refentry> 187 188 <refentry id="frontend_f_close"> 189 <refmeta> 190 <refentrytitle>DVB frontend close()</refentrytitle> 191 &manvol; 192 </refmeta> 193 194 <refnamediv> 195 <refname>fe-close</refname> 196 <refpurpose>Close a frontend device</refpurpose> 197 </refnamediv> 198 199 <refsynopsisdiv> 200 <funcsynopsis> 201 <funcsynopsisinfo>#include <unistd.h></funcsynopsisinfo> 202 <funcprototype> 203 <funcdef>int <function>close</function></funcdef> 204 <paramdef>int <parameter>fd</parameter></paramdef> 205 </funcprototype> 206 </funcsynopsis> 207 </refsynopsisdiv> 208 209 <refsect1> 210 <title>Arguments</title> 211 212 <variablelist> 213 <varlistentry> 214 <term><parameter>fd</parameter></term> 215 <listitem> 216 <para>&fd;</para> 217 </listitem> 218 </varlistentry> 219 </variablelist> 220 </refsect1> 221 222 <refsect1> 223 <title>Description</title> 224 <para>This system call closes a previously opened front-end device. After closing 225 a front-end device, its corresponding hardware might be powered down 226 automatically.</para> 227 </refsect1> 228 <refsect1> 229 <title>Return Value</title> 230 231 <para>The function returns <returnvalue>0</returnvalue> on 232 success, <returnvalue>-1</returnvalue> on failure and the 233 <varname>errno</varname> is set appropriately. Possible error 234 codes:</para> 235 236 <variablelist> 237 <varlistentry> 238 <term><errorcode>EBADF</errorcode></term> 239 <listitem> 240 <para><parameter>fd</parameter> is not a valid open file 241 descriptor.</para> 242 </listitem> 243 </varlistentry> 244 </variablelist> 245 </refsect1> 246 </refentry> 247 248 &sub-fe-get-info; 249 &sub-fe-read-status; 250 &sub-fe-get-property; 251 &sub-fe-diseqc-reset-overload; 252 &sub-fe-diseqc-send-master-cmd; 253 &sub-fe-diseqc-recv-slave-reply; 254 &sub-fe-diseqc-send-burst; 255 &sub-fe-set-tone; 256 &sub-fe-set-voltage; 257 &sub-fe-enable-high-lnb-voltage; 258 &sub-fe-set-frontend-tune-mode; 259 260 </section> 261 262 <section id="frontend_legacy_dvbv3_api"> 263 <title>DVB Frontend legacy API (a. k. a. DVBv3)</title> 264 <para>The usage of this API is deprecated, as it doesn't support all digital 265 TV standards, doesn't provide good statistics measurements and provides 266 incomplete information. This is kept only to support legacy applications.</para> 267 268 &sub-frontend_legacy_api; 269 </section>