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Based on kernel version 4.3. Page generated on 2015-11-02 12:48 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 &lt;fcntl.h&gt;</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 &lt;unistd.h&gt;</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>
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