| .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
| .. c:namespace:: CEC |
| |
| .. _CEC_MODE: |
| .. _CEC_G_MODE: |
| .. _CEC_S_MODE: |
| |
| ******************************** |
| ioctls CEC_G_MODE and CEC_S_MODE |
| ******************************** |
| |
| CEC_G_MODE, CEC_S_MODE - Get or set exclusive use of the CEC adapter |
| |
| Synopsis |
| ======== |
| |
| .. c:macro:: CEC_G_MODE |
| |
| ``int ioctl(int fd, CEC_G_MODE, __u32 *argp)`` |
| |
| .. c:macro:: CEC_S_MODE |
| |
| ``int ioctl(int fd, CEC_S_MODE, __u32 *argp)`` |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :c:func:`open()`. |
| |
| ``argp`` |
| Pointer to CEC mode. |
| |
| Description |
| =========== |
| |
| By default any filehandle can use :ref:`CEC_TRANSMIT`, but in order to prevent |
| applications from stepping on each others toes it must be possible to |
| obtain exclusive access to the CEC adapter. This ioctl sets the |
| filehandle to initiator and/or follower mode which can be exclusive |
| depending on the chosen mode. The initiator is the filehandle that is |
| used to initiate messages, i.e. it commands other CEC devices. The |
| follower is the filehandle that receives messages sent to the CEC |
| adapter and processes them. The same filehandle can be both initiator |
| and follower, or this role can be taken by two different filehandles. |
| |
| When a CEC message is received, then the CEC framework will decide how |
| it will be processed. If the message is a reply to an earlier |
| transmitted message, then the reply is sent back to the filehandle that |
| is waiting for it. In addition the CEC framework will process it. |
| |
| If the message is not a reply, then the CEC framework will process it |
| first. If there is no follower, then the message is just discarded and a |
| feature abort is sent back to the initiator if the framework couldn't |
| process it. If there is a follower, then the message is passed on to the |
| follower who will use :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>` to dequeue |
| the new message. The framework expects the follower to make the right |
| decisions. |
| |
| The CEC framework will process core messages unless requested otherwise |
| by the follower. The follower can enable the passthrough mode. In that |
| case, the CEC framework will pass on most core messages without |
| processing them and the follower will have to implement those messages. |
| There are some messages that the core will always process, regardless of |
| the passthrough mode. See :ref:`cec-core-processing` for details. |
| |
| If there is no initiator, then any CEC filehandle can use |
| :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`. If there is an exclusive |
| initiator then only that initiator can call |
| :ref:`CEC_TRANSMIT`. The follower can of course |
| always call :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`. |
| |
| Available initiator modes are: |
| |
| .. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{10.8cm}| |
| |
| .. _cec-mode-initiator_e: |
| |
| .. flat-table:: Initiator Modes |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 16 |
| |
| * .. _`CEC-MODE-NO-INITIATOR`: |
| |
| - ``CEC_MODE_NO_INITIATOR`` |
| - 0x0 |
| - This is not an initiator, i.e. it cannot transmit CEC messages or |
| make any other changes to the CEC adapter. |
| * .. _`CEC-MODE-INITIATOR`: |
| |
| - ``CEC_MODE_INITIATOR`` |
| - 0x1 |
| - This is an initiator (the default when the device is opened) and |
| it can transmit CEC messages and make changes to the CEC adapter, |
| unless there is an exclusive initiator. |
| * .. _`CEC-MODE-EXCL-INITIATOR`: |
| |
| - ``CEC_MODE_EXCL_INITIATOR`` |
| - 0x2 |
| - This is an exclusive initiator and this file descriptor is the |
| only one that can transmit CEC messages and make changes to the |
| CEC adapter. If someone else is already the exclusive initiator |
| then an attempt to become one will return the ``EBUSY`` error code |
| error. |
| |
| Available follower modes are: |
| |
| .. tabularcolumns:: |p{6.6cm}|p{0.9cm}|p{9.8cm}| |
| |
| .. _cec-mode-follower_e: |
| |
| .. cssclass:: longtable |
| |
| .. flat-table:: Follower Modes |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 16 |
| |
| * .. _`CEC-MODE-NO-FOLLOWER`: |
| |
| - ``CEC_MODE_NO_FOLLOWER`` |
| - 0x00 |
| - This is not a follower (the default when the device is opened). |
| * .. _`CEC-MODE-FOLLOWER`: |
| |
| - ``CEC_MODE_FOLLOWER`` |
| - 0x10 |
| - This is a follower and it will receive CEC messages unless there |
| is an exclusive follower. You cannot become a follower if |
| :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` |
| was specified, the ``EINVAL`` error code is returned in that case. |
| * .. _`CEC-MODE-EXCL-FOLLOWER`: |
| |
| - ``CEC_MODE_EXCL_FOLLOWER`` |
| - 0x20 |
| - This is an exclusive follower and only this file descriptor will |
| receive CEC messages for processing. If someone else is already |
| the exclusive follower then an attempt to become one will return |
| the ``EBUSY`` error code. You cannot become a follower if |
| :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` |
| was specified, the ``EINVAL`` error code is returned in that case. |
| * .. _`CEC-MODE-EXCL-FOLLOWER-PASSTHRU`: |
| |
| - ``CEC_MODE_EXCL_FOLLOWER_PASSTHRU`` |
| - 0x30 |
| - This is an exclusive follower and only this file descriptor will |
| receive CEC messages for processing. In addition it will put the |
| CEC device into passthrough mode, allowing the exclusive follower |
| to handle most core messages instead of relying on the CEC |
| framework for that. If someone else is already the exclusive |
| follower then an attempt to become one will return the ``EBUSY`` error |
| code. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` |
| is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified, |
| the ``EINVAL`` error code is returned in that case. |
| * .. _`CEC-MODE-MONITOR-PIN`: |
| |
| - ``CEC_MODE_MONITOR_PIN`` |
| - 0xd0 |
| - Put the file descriptor into pin monitoring mode. Can only be used in |
| combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, |
| otherwise the ``EINVAL`` error code will be returned. |
| This mode requires that the :ref:`CEC_CAP_MONITOR_PIN <CEC-CAP-MONITOR-PIN>` |
| capability is set, otherwise the ``EINVAL`` error code is returned. |
| While in pin monitoring mode this file descriptor can receive the |
| ``CEC_EVENT_PIN_CEC_LOW`` and ``CEC_EVENT_PIN_CEC_HIGH`` events to see the |
| low-level CEC pin transitions. This is very useful for debugging. |
| This mode is only allowed if the process has the ``CAP_NET_ADMIN`` |
| capability. If that is not set, then the ``EPERM`` error code is returned. |
| * .. _`CEC-MODE-MONITOR`: |
| |
| - ``CEC_MODE_MONITOR`` |
| - 0xe0 |
| - Put the file descriptor into monitor mode. Can only be used in |
| combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, |
| otherwise the ``EINVAL`` error code will be returned. |
| In monitor mode all messages this CEC |
| device transmits and all messages it receives (both broadcast |
| messages and directed messages for one its logical addresses) will |
| be reported. This is very useful for debugging. This is only |
| allowed if the process has the ``CAP_NET_ADMIN`` capability. If |
| that is not set, then the ``EPERM`` error code is returned. |
| * .. _`CEC-MODE-MONITOR-ALL`: |
| |
| - ``CEC_MODE_MONITOR_ALL`` |
| - 0xf0 |
| - Put the file descriptor into 'monitor all' mode. Can only be used |
| in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise |
| the ``EINVAL`` error code will be returned. In 'monitor all' mode all messages |
| this CEC device transmits and all messages it receives, including |
| directed messages for other CEC devices, will be reported. This is |
| very useful for debugging, but not all devices support this. This |
| mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set, |
| otherwise the ``EINVAL`` error code is returned. This is only allowed if |
| the process has the ``CAP_NET_ADMIN`` capability. If that is not |
| set, then the ``EPERM`` error code is returned. |
| |
| Core message processing details: |
| |
| .. tabularcolumns:: |p{6.6cm}|p{10.9cm}| |
| |
| .. _cec-core-processing: |
| |
| .. flat-table:: Core Message Processing |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 8 |
| |
| * .. _`CEC-MSG-GET-CEC-VERSION`: |
| |
| - ``CEC_MSG_GET_CEC_VERSION`` |
| - The core will return the CEC version that was set with |
| :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`, |
| except when in passthrough mode. In passthrough mode the core |
| does nothing and this message has to be handled by a follower |
| instead. |
| * .. _`CEC-MSG-GIVE-DEVICE-VENDOR-ID`: |
| |
| - ``CEC_MSG_GIVE_DEVICE_VENDOR_ID`` |
| - The core will return the vendor ID that was set with |
| :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`, |
| except when in passthrough mode. In passthrough mode the core |
| does nothing and this message has to be handled by a follower |
| instead. |
| * .. _`CEC-MSG-ABORT`: |
| |
| - ``CEC_MSG_ABORT`` |
| - The core will return a Feature Abort message with reason |
| 'Feature Refused' as per the specification, except when in |
| passthrough mode. In passthrough mode the core does nothing |
| and this message has to be handled by a follower instead. |
| * .. _`CEC-MSG-GIVE-PHYSICAL-ADDR`: |
| |
| - ``CEC_MSG_GIVE_PHYSICAL_ADDR`` |
| - The core will report the current physical address, except when |
| in passthrough mode. In passthrough mode the core does nothing |
| and this message has to be handled by a follower instead. |
| * .. _`CEC-MSG-GIVE-OSD-NAME`: |
| |
| - ``CEC_MSG_GIVE_OSD_NAME`` |
| - The core will report the current OSD name that was set with |
| :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`, |
| except when in passthrough mode. In passthrough mode the core |
| does nothing and this message has to be handled by a follower |
| instead. |
| * .. _`CEC-MSG-GIVE-FEATURES`: |
| |
| - ``CEC_MSG_GIVE_FEATURES`` |
| - The core will do nothing if the CEC version is older than 2.0, |
| otherwise it will report the current features that were set with |
| :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`, |
| except when in passthrough mode. In passthrough mode the core |
| does nothing (for any CEC version) and this message has to be handled |
| by a follower instead. |
| * .. _`CEC-MSG-USER-CONTROL-PRESSED`: |
| |
| - ``CEC_MSG_USER_CONTROL_PRESSED`` |
| - If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set and if |
| :ref:`CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU <CEC-LOG-ADDRS-FL-ALLOW-RC-PASSTHRU>` |
| is set, then generate a remote control key |
| press. This message is always passed on to the follower(s). |
| * .. _`CEC-MSG-USER-CONTROL-RELEASED`: |
| |
| - ``CEC_MSG_USER_CONTROL_RELEASED`` |
| - If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set and if |
| :ref:`CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU <CEC-LOG-ADDRS-FL-ALLOW-RC-PASSTHRU>` |
| is set, then generate a remote control key |
| release. This message is always passed on to the follower(s). |
| * .. _`CEC-MSG-REPORT-PHYSICAL-ADDR`: |
| |
| - ``CEC_MSG_REPORT_PHYSICAL_ADDR`` |
| - The CEC framework will make note of the reported physical address |
| and then just pass the message on to the follower(s). |
| |
| |
| Return Value |
| ============ |
| |
| On success 0 is returned, on error -1 and the ``errno`` variable is set |
| appropriately. The generic error codes are described at the |
| :ref:`Generic Error Codes <gen-errors>` chapter. |
| |
| The :ref:`ioctl CEC_S_MODE <CEC_S_MODE>` can return the following |
| error codes: |
| |
| EINVAL |
| The requested mode is invalid. |
| |
| EPERM |
| Monitor mode is requested, but the process does have the ``CAP_NET_ADMIN`` |
| capability. |
| |
| EBUSY |
| Someone else is already an exclusive follower or initiator. |
