1 .. -*- coding: utf-8; mode: rst -*-
7 ********************************
8 ioctls CEC_G_MODE and CEC_S_MODE
9 ********************************
11 CEC_G_MODE, CEC_S_MODE - Get or set exclusive use of the CEC adapter
16 .. c:function:: int ioctl( int fd, int request, __u32 *argp )
22 File descriptor returned by :ref:`open() <cec-func-open>`.
25 CEC_G_MODE, CEC_S_MODE
35 This documents the proposed CEC API. This API is not yet finalized
36 and is currently only available as a staging kernel module.
38 By default any filehandle can use :ref:`CEC_TRANSMIT`, but in order to prevent
39 applications from stepping on each others toes it must be possible to
40 obtain exclusive access to the CEC adapter. This ioctl sets the
41 filehandle to initiator and/or follower mode which can be exclusive
42 depending on the chosen mode. The initiator is the filehandle that is
43 used to initiate messages, i.e. it commands other CEC devices. The
44 follower is the filehandle that receives messages sent to the CEC
45 adapter and processes them. The same filehandle can be both initiator
46 and follower, or this role can be taken by two different filehandles.
48 When a CEC message is received, then the CEC framework will decide how
49 it will be processed. If the message is a reply to an earlier
50 transmitted message, then the reply is sent back to the filehandle that
51 is waiting for it. In addition the CEC framework will process it.
53 If the message is not a reply, then the CEC framework will process it
54 first. If there is no follower, then the message is just discarded and a
55 feature abort is sent back to the initiator if the framework couldn't
56 process it. If there is a follower, then the message is passed on to the
57 follower who will use :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>` to dequeue
58 the new message. The framework expects the follower to make the right
61 The CEC framework will process core messages unless requested otherwise
62 by the follower. The follower can enable the passthrough mode. In that
63 case, the CEC framework will pass on most core messages without
64 processing them and the follower will have to implement those messages.
65 There are some messages that the core will always process, regardless of
66 the passthrough mode. See :ref:`cec-core-processing` for details.
68 If there is no initiator, then any CEC filehandle can use
69 :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`. If there is an exclusive
70 initiator then only that initiator can call
71 :ref:`CEC_TRANSMIT`. The follower can of course
72 always call :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`.
74 Available initiator modes are:
76 .. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{11.0cm}|
78 .. _cec-mode-initiator_e:
80 .. flat-table:: Initiator Modes
86 - .. _`CEC-MODE-NO-INITIATOR`:
88 - ``CEC_MODE_NO_INITIATOR``
92 - This is not an initiator, i.e. it cannot transmit CEC messages or
93 make any other changes to the CEC adapter.
95 - .. _`CEC-MODE-INITIATOR`:
97 - ``CEC_MODE_INITIATOR``
101 - This is an initiator (the default when the device is opened) and
102 it can transmit CEC messages and make changes to the CEC adapter,
103 unless there is an exclusive initiator.
105 - .. _`CEC-MODE-EXCL-INITIATOR`:
107 - ``CEC_MODE_EXCL_INITIATOR``
111 - This is an exclusive initiator and this file descriptor is the
112 only one that can transmit CEC messages and make changes to the
113 CEC adapter. If someone else is already the exclusive initiator
114 then an attempt to become one will return the ``EBUSY`` error code
118 Available follower modes are:
120 .. tabularcolumns:: |p{6.6cm}|p{0.9cm}|p{10.0cm}|
122 .. _cec-mode-follower_e:
124 .. flat-table:: Follower Modes
130 - .. _`CEC-MODE-NO-FOLLOWER`:
132 - ``CEC_MODE_NO_FOLLOWER``
136 - This is not a follower (the default when the device is opened).
138 - .. _`CEC-MODE-FOLLOWER`:
140 - ``CEC_MODE_FOLLOWER``
144 - This is a follower and it will receive CEC messages unless there
145 is an exclusive follower. You cannot become a follower if
146 :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
147 was specified, the ``EINVAL`` error code is returned in that case.
149 - .. _`CEC-MODE-EXCL-FOLLOWER`:
151 - ``CEC_MODE_EXCL_FOLLOWER``
155 - This is an exclusive follower and only this file descriptor will
156 receive CEC messages for processing. If someone else is already
157 the exclusive follower then an attempt to become one will return
158 the ``EBUSY`` error code. You cannot become a follower if
159 :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
160 was specified, the ``EINVAL`` error code is returned in that case.
162 - .. _`CEC-MODE-EXCL-FOLLOWER-PASSTHRU`:
164 - ``CEC_MODE_EXCL_FOLLOWER_PASSTHRU``
168 - This is an exclusive follower and only this file descriptor will
169 receive CEC messages for processing. In addition it will put the
170 CEC device into passthrough mode, allowing the exclusive follower
171 to handle most core messages instead of relying on the CEC
172 framework for that. If someone else is already the exclusive
173 follower then an attempt to become one will return the ``EBUSY`` error
174 code. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
175 is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified,
176 the ``EINVAL`` error code is returned in that case.
178 - .. _`CEC-MODE-MONITOR`:
180 - ``CEC_MODE_MONITOR``
184 - Put the file descriptor into monitor mode. Can only be used in
185 combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL error
186 code will be returned. In monitor mode all messages this CEC
187 device transmits and all messages it receives (both broadcast
188 messages and directed messages for one its logical addresses) will
189 be reported. This is very useful for debugging. This is only
190 allowed if the process has the ``CAP_NET_ADMIN`` capability. If
191 that is not set, then the ``EPERM`` error code is returned.
193 - .. _`CEC-MODE-MONITOR-ALL`:
195 - ``CEC_MODE_MONITOR_ALL``
199 - Put the file descriptor into 'monitor all' mode. Can only be used
200 in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise
201 the ``EINVAL`` error code will be returned. In 'monitor all' mode all messages
202 this CEC device transmits and all messages it receives, including
203 directed messages for other CEC devices will be reported. This is
204 very useful for debugging, but not all devices support this. This
205 mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set,
206 otherwise the ``EINVAL`` error code is returned. This is only allowed if
207 the process has the ``CAP_NET_ADMIN`` capability. If that is not
208 set, then the ``EPERM`` error code is returned.
211 Core message processing details:
213 .. tabularcolumns:: |p{6.6cm}|p{10.9cm}|
215 .. _cec-core-processing:
217 .. flat-table:: Core Message Processing
223 - .. _`CEC-MSG-GET-CEC-VERSION`:
225 - ``CEC_MSG_GET_CEC_VERSION``
227 - When in passthrough mode this message has to be handled by
228 userspace, otherwise the core will return the CEC version that was
229 set with :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`.
231 - .. _`CEC-MSG-GIVE-DEVICE-VENDOR-ID`:
233 - ``CEC_MSG_GIVE_DEVICE_VENDOR_ID``
235 - When in passthrough mode this message has to be handled by
236 userspace, otherwise the core will return the vendor ID that was
237 set with :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`.
239 - .. _`CEC-MSG-ABORT`:
243 - When in passthrough mode this message has to be handled by
244 userspace, otherwise the core will return a feature refused
245 message as per the specification.
247 - .. _`CEC-MSG-GIVE-PHYSICAL-ADDR`:
249 - ``CEC_MSG_GIVE_PHYSICAL_ADDR``
251 - When in passthrough mode this message has to be handled by
252 userspace, otherwise the core will report the current physical
255 - .. _`CEC-MSG-GIVE-OSD-NAME`:
257 - ``CEC_MSG_GIVE_OSD_NAME``
259 - When in passthrough mode this message has to be handled by
260 userspace, otherwise the core will report the current OSD name as
261 was set with :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`.
263 - .. _`CEC-MSG-GIVE-FEATURES`:
265 - ``CEC_MSG_GIVE_FEATURES``
267 - When in passthrough mode this message has to be handled by
268 userspace, otherwise the core will report the current features as
269 was set with :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
270 or the message is ignored if the CEC version was older than 2.0.
272 - .. _`CEC-MSG-USER-CONTROL-PRESSED`:
274 - ``CEC_MSG_USER_CONTROL_PRESSED``
276 - If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set, then generate a remote control key
277 press. This message is always passed on to userspace.
279 - .. _`CEC-MSG-USER-CONTROL-RELEASED`:
281 - ``CEC_MSG_USER_CONTROL_RELEASED``
283 - If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set, then generate a remote control key
284 release. This message is always passed on to userspace.
286 - .. _`CEC-MSG-REPORT-PHYSICAL-ADDR`:
288 - ``CEC_MSG_REPORT_PHYSICAL_ADDR``
290 - The CEC framework will make note of the reported physical address
291 and then just pass the message on to userspace.
298 On success 0 is returned, on error -1 and the ``errno`` variable is set
299 appropriately. The generic error codes are described at the
300 :ref:`Generic Error Codes <gen-errors>` chapter.