forked from luck/tmp_suning_uos_patched
90 lines
3.5 KiB
Plaintext
90 lines
3.5 KiB
Plaintext
|
rfkill - RF switch subsystem support
|
||
|
|
====================================
|
||
|
|
|
||
|
|
1 Implementation details
|
||
|
|
2 Driver support
|
||
|
|
3 Userspace support
|
||
|
|
|
||
|
|
===============================================================================
|
||
|
|
1: Implementation details
|
||
|
|
|
||
|
|
The rfkill switch subsystem offers support for keys often found on laptops
|
||
|
|
to enable wireless devices like WiFi and Bluetooth.
|
||
|
|
|
||
|
|
This is done by providing the user 3 possibilities:
|
||
|
|
1 - The rfkill system handles all events; userspace is not aware of events.
|
||
|
|
2 - The rfkill system handles all events; userspace is informed about the events.
|
||
|
|
3 - The rfkill system does not handle events; userspace handles all events.
|
||
|
|
|
||
|
|
The buttons to enable and disable the wireless radios are important in
|
||
|
|
situations where the user is for example using his laptop on a location where
|
||
|
|
wireless radios _must_ be disabled (e.g. airplanes).
|
||
|
|
Because of this requirement, userspace support for the keys should not be
|
||
|
|
made mandatory. Because userspace might want to perform some additional smarter
|
||
|
|
tasks when the key is pressed, rfkill still provides userspace the possibility
|
||
|
|
to take over the task to handle the key events.
|
||
|
|
|
||
|
|
The system inside the kernel has been split into 2 separate sections:
|
||
|
|
1 - RFKILL
|
||
|
|
2 - RFKILL_INPUT
|
||
|
|
|
||
|
|
The first option enables rfkill support and will make sure userspace will
|
||
|
|
be notified of any events through the input device. It also creates several
|
||
|
|
sysfs entries which can be used by userspace. See section "Userspace support".
|
||
|
|
|
||
|
|
The second option provides an rfkill input handler. This handler will
|
||
|
|
listen to all rfkill key events and will toggle the radio accordingly.
|
||
|
|
With this option enabled userspace could either do nothing or simply
|
||
|
|
perform monitoring tasks.
|
||
|
|
|
||
|
|
====================================
|
||
|
|
2: Driver support
|
||
|
|
|
||
|
|
To build a driver with rfkill subsystem support, the driver should
|
||
|
|
depend on the Kconfig symbol RFKILL; it should _not_ depend on
|
||
|
|
RKFILL_INPUT.
|
||
|
|
|
||
|
|
Unless key events trigger an interrupt to which the driver listens, polling
|
||
|
|
will be required to determine the key state changes. For this the input
|
||
|
|
layer providers the input-polldev handler.
|
||
|
|
|
||
|
|
A driver should implement a few steps to correctly make use of the
|
||
|
|
rfkill subsystem. First for non-polling drivers:
|
||
|
|
|
||
|
|
- rfkill_allocate()
|
||
|
|
- input_allocate_device()
|
||
|
|
- rfkill_register()
|
||
|
|
- input_register_device()
|
||
|
|
|
||
|
|
For polling drivers:
|
||
|
|
|
||
|
|
- rfkill_allocate()
|
||
|
|
- input_allocate_polled_device()
|
||
|
|
- rfkill_register()
|
||
|
|
- input_register_polled_device()
|
||
|
|
|
||
|
|
When a key event has been detected, the correct event should be
|
||
|
|
sent over the input device which has been registered by the driver.
|
||
|
|
|
||
|
|
====================================
|
||
|
|
3: Userspace support
|
||
|
|
|
||
|
|
For each key an input device will be created which will send out the correct
|
||
|
|
key event when the rfkill key has been pressed.
|
||
|
|
|
||
|
|
The following sysfs entries will be created:
|
||
|
|
|
||
|
|
name: Name assigned by driver to this key (interface or driver name).
|
||
|
|
type: Name of the key type ("wlan", "bluetooth", etc).
|
||
|
|
state: Current state of the key. 1: On, 0: Off.
|
||
|
|
claim: 1: Userspace handles events, 0: Kernel handles events
|
||
|
|
|
||
|
|
Both the "state" and "claim" entries are also writable. For the "state" entry
|
||
|
|
this means that when 1 or 0 is written all radios, not yet in the requested
|
||
|
|
state, will be will be toggled accordingly.
|
||
|
|
For the "claim" entry writing 1 to it means that the kernel no longer handles
|
||
|
|
key events even though RFKILL_INPUT input was enabled. When "claim" has been
|
||
|
|
set to 0, userspace should make sure that it listens for the input events or
|
||
|
|
check the sysfs "state" entry regularly to correctly perform the required
|
||
|
|
tasks when the rkfill key is pressed.
|