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312 lines
9.9 KiB
ReStructuredText
312 lines
9.9 KiB
ReStructuredText
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.. -*- coding: utf-8; mode: rst -*-
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.. _cec-ioc-g-mode:
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****************************
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ioctl CEC_G_MODE, CEC_S_MODE
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****************************
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*man CEC_G_MODE(2)*
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CEC_S_MODE
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Get or set exclusive use of the CEC adapter
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Synopsis
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========
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.. c:function:: int ioctl( int fd, int request, __u32 *argp )
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Arguments
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=========
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``fd``
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File descriptor returned by :ref:`open() <cec-func-open>`.
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``request``
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CEC_G_MODE, CEC_S_MODE
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``argp``
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Description
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===========
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Note: this documents the proposed CEC API. This API is not yet finalized
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and is currently only available as a staging kernel module.
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By default any filehandle can use
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:ref:`CEC_TRANSMIT <cec-ioc-receive>` and
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:ref:`CEC_RECEIVE <cec-ioc-receive>`, but in order to prevent
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applications from stepping on each others toes it must be possible to
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obtain exclusive access to the CEC adapter. This ioctl sets the
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filehandle to initiator and/or follower mode which can be exclusive
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depending on the chosen mode. The initiator is the filehandle that is
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used to initiate messages, i.e. it commands other CEC devices. The
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follower is the filehandle that receives messages sent to the CEC
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adapter and processes them. The same filehandle can be both initiator
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and follower, or this role can be taken by two different filehandles.
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When a CEC message is received, then the CEC framework will decide how
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it will be processed. If the message is a reply to an earlier
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transmitted message, then the reply is sent back to the filehandle that
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is waiting for it. In addition the CEC framework will process it.
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If the message is not a reply, then the CEC framework will process it
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first. If there is no follower, then the message is just discarded and a
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feature abort is sent back to the initiator if the framework couldn't
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process it. If there is a follower, then the message is passed on to the
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follower who will use :ref:`CEC_RECEIVE <cec-ioc-receive>` to dequeue
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the new message. The framework expects the follower to make the right
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decisions.
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The CEC framework will process core messages unless requested otherwise
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by the follower. The follower can enable the passthrough mode. In that
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case, the CEC framework will pass on most core messages without
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processing them and the follower will have to implement those messages.
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There are some messages that the core will always process, regardless of
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the passthrough mode. See :ref:`cec-core-processing` for details.
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If there is no initiator, then any CEC filehandle can use
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:ref:`CEC_TRANSMIT <cec-ioc-receive>`. If there is an exclusive
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initiator then only that initiator can call
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:ref:`CEC_TRANSMIT <cec-ioc-receive>`. The follower can of course
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always call :ref:`CEC_TRANSMIT <cec-ioc-receive>`.
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Available initiator modes are:
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.. _cec-mode-initiator:
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.. flat-table:: Initiator Modes
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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- .. row 1
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- ``CEC_MODE_NO_INITIATOR``
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- 0x0
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- This is not an initiator, i.e. it cannot transmit CEC messages or
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make any other changes to the CEC adapter.
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- .. row 2
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- ``CEC_MODE_INITIATOR``
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- 0x1
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- This is an initiator (the default when the device is opened) and
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it can transmit CEC messages and make changes to the CEC adapter,
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unless there is an exclusive initiator.
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- .. row 3
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- ``CEC_MODE_EXCL_INITIATOR``
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- 0x2
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- This is an exclusive initiator and this file descriptor is the
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only one that can transmit CEC messages and make changes to the
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CEC adapter. If someone else is already the exclusive initiator
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then an attempt to become one will return the EBUSY error code
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error.
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Available follower modes are:
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.. _cec-mode-follower:
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.. flat-table:: Follower Modes
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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- .. row 1
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- ``CEC_MODE_NO_FOLLOWER``
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- 0x00
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- This is not a follower (the default when the device is opened).
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- .. row 2
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- ``CEC_MODE_FOLLOWER``
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- 0x10
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- This is a follower and it will receive CEC messages unless there
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is an exclusive follower. You cannot become a follower if
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``CEC_CAP_TRANSMIT`` is not set or if ``CEC_MODE_NO_INITIATOR``
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was specified, EINVAL error code is returned in that case.
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- .. row 3
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- ``CEC_MODE_EXCL_FOLLOWER``
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- 0x20
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- This is an exclusive follower and only this file descriptor will
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receive CEC messages for processing. If someone else is already
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the exclusive follower then an attempt to become one will return
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the EBUSY error code error. You cannot become a follower if
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``CEC_CAP_TRANSMIT`` is not set or if ``CEC_MODE_NO_INITIATOR``
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was specified, EINVAL error code is returned in that case.
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- .. row 4
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- ``CEC_MODE_EXCL_FOLLOWER_PASSTHRU``
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- 0x30
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- This is an exclusive follower and only this file descriptor will
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receive CEC messages for processing. In addition it will put the
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CEC device into passthrough mode, allowing the exclusive follower
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to handle most core messages instead of relying on the CEC
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framework for that. If someone else is already the exclusive
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follower then an attempt to become one will return the EBUSY error
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code error. You cannot become a follower if ``CEC_CAP_TRANSMIT``
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is not set or if ``CEC_MODE_NO_INITIATOR`` was specified, EINVAL
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error code is returned in that case.
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- .. row 5
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- ``CEC_MODE_MONITOR``
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- 0xe0
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- Put the file descriptor into monitor mode. Can only be used in
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combination with ``CEC_MODE_NO_INITIATOR``, otherwise EINVAL error
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code will be returned. In monitor mode all messages this CEC
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device transmits and all messages it receives (both broadcast
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messages and directed messages for one its logical addresses) will
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be reported. This is very useful for debugging. This is only
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allowed if the process has the ``CAP_NET_ADMIN`` capability. If
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that is not set, then EPERM error code is returned.
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- .. row 6
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- ``CEC_MODE_MONITOR_ALL``
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- 0xf0
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- Put the file descriptor into 'monitor all' mode. Can only be used
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in combination with ``CEC_MODE_NO_INITIATOR``, otherwise EINVAL
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error code will be returned. In 'monitor all' mode all messages
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this CEC device transmits and all messages it receives, including
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directed messages for other CEC devices will be reported. This is
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very useful for debugging, but not all devices support this. This
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mode requires that the ``CEC_CAP_MONITOR_ALL`` capability is set,
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otherwise EINVAL error code is returned. This is only allowed if
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the process has the ``CAP_NET_ADMIN`` capability. If that is not
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set, then EPERM error code is returned.
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Core message processing details:
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.. _cec-core-processing:
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.. flat-table:: Core Message Processing
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:header-rows: 0
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:stub-columns: 0
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- .. row 1
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- ``CEC_MSG_GET_CEC_VERSION``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will return the CEC version that was
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set with
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:ref:`CEC_ADAP_S_LOG_ADDRS <cec-ioc-adap-g-log-addrs>`.
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- .. row 2
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- ``CEC_MSG_GIVE_DEVICE_VENDOR_ID``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will return the vendor ID that was
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set with
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:ref:`CEC_ADAP_S_LOG_ADDRS <cec-ioc-adap-g-log-addrs>`.
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- .. row 3
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- ``CEC_MSG_ABORT``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will return a feature refused
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message as per the specification.
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- .. row 4
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- ``CEC_MSG_GIVE_PHYSICAL_ADDR``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will report the current physical
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address.
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- .. row 5
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- ``CEC_MSG_GIVE_OSD_NAME``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will report the current OSD name as
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was set with
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:ref:`CEC_ADAP_S_LOG_ADDRS <cec-ioc-adap-g-log-addrs>`.
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- .. row 6
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- ``CEC_MSG_GIVE_FEATURES``
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- When in passthrough mode this message has to be handled by
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userspace, otherwise the core will report the current features as
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was set with
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:ref:`CEC_ADAP_S_LOG_ADDRS <cec-ioc-adap-g-log-addrs>` or
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the message is ignore if the CEC version was older than 2.0.
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- .. row 7
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- ``CEC_MSG_USER_CONTROL_PRESSED``
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- If ``CEC_CAP_RC`` is set, then generate a remote control key
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press. This message is always passed on to userspace.
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- .. row 8
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- ``CEC_MSG_USER_CONTROL_RELEASED``
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- If ``CEC_CAP_RC`` is set, then generate a remote control key
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release. This message is always passed on to userspace.
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- .. row 9
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- ``CEC_MSG_REPORT_PHYSICAL_ADDR``
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- The CEC framework will make note of the reported physical address
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and then just pass the message on to userspace.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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.. ------------------------------------------------------------------------------
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.. This file was automatically converted from DocBook-XML with the dbxml
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.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
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.. from the linux kernel, refer to:
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..
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.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
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.. ------------------------------------------------------------------------------
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