Based on kernel version 2.6.25. Page generated on 2008-04-18 21:22 EST.
1 rfkill - RF switch subsystem support 2 ==================================== 3 4 1 Implementation details 5 2 Driver support 6 3 Userspace support 7 8 =============================================================================== 9 1: Implementation details 10 11 The rfkill switch subsystem offers support for keys often found on laptops 12 to enable wireless devices like WiFi and Bluetooth. 13 14 This is done by providing the user 3 possibilities: 15 1 - The rfkill system handles all events; userspace is not aware of events. 16 2 - The rfkill system handles all events; userspace is informed about the events. 17 3 - The rfkill system does not handle events; userspace handles all events. 18 19 The buttons to enable and disable the wireless radios are important in 20 situations where the user is for example using his laptop on a location where 21 wireless radios _must_ be disabled (e.g. airplanes). 22 Because of this requirement, userspace support for the keys should not be 23 made mandatory. Because userspace might want to perform some additional smarter 24 tasks when the key is pressed, rfkill still provides userspace the possibility 25 to take over the task to handle the key events. 26 27 The system inside the kernel has been split into 2 separate sections: 28 1 - RFKILL 29 2 - RFKILL_INPUT 30 31 The first option enables rfkill support and will make sure userspace will 32 be notified of any events through the input device. It also creates several 33 sysfs entries which can be used by userspace. See section "Userspace support". 34 35 The second option provides an rfkill input handler. This handler will 36 listen to all rfkill key events and will toggle the radio accordingly. 37 With this option enabled userspace could either do nothing or simply 38 perform monitoring tasks. 39 40 ==================================== 41 2: Driver support 42 43 To build a driver with rfkill subsystem support, the driver should 44 depend on the Kconfig symbol RFKILL; it should _not_ depend on 45 RKFILL_INPUT. 46 47 Unless key events trigger an interrupt to which the driver listens, polling 48 will be required to determine the key state changes. For this the input 49 layer providers the input-polldev handler. 50 51 A driver should implement a few steps to correctly make use of the 52 rfkill subsystem. First for non-polling drivers: 53 54 - rfkill_allocate() 55 - input_allocate_device() 56 - rfkill_register() 57 - input_register_device() 58 59 For polling drivers: 60 61 - rfkill_allocate() 62 - input_allocate_polled_device() 63 - rfkill_register() 64 - input_register_polled_device() 65 66 When a key event has been detected, the correct event should be 67 sent over the input device which has been registered by the driver. 68 69 ==================================== 70 3: Userspace support 71 72 For each key an input device will be created which will send out the correct 73 key event when the rfkill key has been pressed. 74 75 The following sysfs entries will be created: 76 77 name: Name assigned by driver to this key (interface or driver name). 78 type: Name of the key type ("wlan", "bluetooth", etc). 79 state: Current state of the key. 1: On, 0: Off. 80 claim: 1: Userspace handles events, 0: Kernel handles events 81 82 Both the "state" and "claim" entries are also writable. For the "state" entry 83 this means that when 1 or 0 is written all radios, not yet in the requested 84 state, will be will be toggled accordingly. 85 For the "claim" entry writing 1 to it means that the kernel no longer handles 86 key events even though RFKILL_INPUT input was enabled. When "claim" has been 87 set to 0, userspace should make sure that it listens for the input events or 88 check the sysfs "state" entry regularly to correctly perform the required 89 tasks when the rkfill key is pressed.
