Messages in this thread | | | Date | Mon, 7 Jan 2008 09:20:40 -0500 | From | "Dmitry Torokhov" <> | Subject | Re: acpi/apm events as inputs: how to handle? |
| |
Hi,
On Jan 7, 2008 8:03 AM, Andrey Borzenkov <arvidjaar@mail.ru> wrote: > Michael Tokarev wrote: > > > Dmitry Torokhov wrote: > >> Hi Michael, > > > > Hello! > > > > [] > >> There are keyboards (USB, PS2) with Sleep and Suspend buttons > >> that are not related to ACPI nor APM. We had 2 options - add > >> an input handler that would translate input events into ACPI > >> events and feed /proc/acpi/event[*] or go other way around and > >> use input layer for delivering suspend and sleep requests for > >> all types of keyboards/buttons, including ACPI buttons. The > >> secons option is better because userspace solution using input > >> layer will not be tied to a particular technology (ACPI) and > >> can be used on other platforms as well. > > > > Aha, this makes sense. > > And it brings a few questions, too. > > > > As far as I can see, there's little information about how to > > actually use the input interface. Let's suppose I'm about to > > write an application (a daemon) that should replace acpid -- > > it's handling of the said buttons (power and sleep). How to > > find the right devices? Should it use /dev/input/event* or > > something else? How about handling hot-plugged devices like > > new (and removed) keyboards? (And yes, my keyboard has a sleep > > button.)
I think the best ways is to listen to hotplug events in some fashion. Raw netlink, D-Bus, etc.
> > > > Well, you use event device in any case; as for finding right one - I guess > you look at device capabilities and filter what you need ... > > {pts/0}% > cat /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/capabilities/key > 100000 0 0 0 >
Exactly. Any driver working through evdev interface should examine device's capabilities and decide whether it is interested in the device or not.
> you could also check name but I guess it is unreliable > > {pts/0}% cat /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/name > Power Button (FF) > > Then you have your event device: > > {pts/0}% ll -d /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1 > drwxr-xr-x 3 root root 0 2008-01-07 > 15:32 /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1/ > > the problem that you *really* have - nobody prevents user from using udev to > renaming /dev/input/event1 away into anything (s)he likes. Of course you > could do > > {pts/0}% > udevinfo --query=name --path /devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1 > input/event1 > > .. but at some point we have to commit to support this interface forever. >
/sys/class/input/event0/device pointe to corrseponding input device and you can get capabilities from there. /sys/class/input/event0/dev contains dev_t so if you don't see proper/ /dev/input/eevent* you can create your own.
> > And by the way, what INPUT can one expect from a PC speaker? > > input: PC Speaker as /devices/platform/pcspkr/input/input0 > >
Speaker is tied very closely to keyboard beeps and that's why it is part of input system.
> > I ask myself about LNXVIDEO as well. > > /devices/LNXSYSTM:00/device:00/PNP0A03:00/device:13/LNXVIDEO:00/input/input3/event3/
There are keys that are tied in firmware to the video device that switch between CRT and LCD on laptops. They emit events like KEY_SWITCHVIDEOMODE and so input device was needed.
-- Dmitry
| |