Adding input_id to udev

[Martin Pitt <martin.pitt@ubuntu.com>]

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Hello,

in the course of udevifying X.org, we determined that we need a
reliable way of detecting whether an input device is a touchpad (and
thus should be driven by -synaptics instead of -evdev). Our first
attempt [1] uses ATTRS{protocol}=="AlpsPS/2", but that misses a lot of
devices using other protocols.

So at least for now it would be better to actually check the
inputN/capabilities/{key,abs} flags in sysfs, like hal used to do.

I took the hal code as a basis and created an input_id program [2]
which detects the class of a device (since bit testing in udev rules
isn't possible). We can then use this in X.org's and potentially other
rules.

Questions:

 * Should we maintain this in udev proper, in extras/input_id/ ? (My
   preferred solution, since it's not really X.org specific). I'm up
   for maintaining it.

 * Should udev itself install rules which call this, or should we just
   provide it for other packages to use? Calling it in udev itself
   feels a little more robust to me, but it would mean that the
   probing would be done in vain on systems which use X.org with hal.

   Something like

   ACTION=="add|change", SUBSYSTEM=="input", ENV{ID_INPUT}=="", IMPORT{program}="input_id /sys/%p"

   (I'll drop the /sys/ and move it into input_id.c before committing)

Thanks in advance for comments,

Martin


On my system:

$ gcc -o input_id input_id.c
$ for i in /sys/class/input/input*; do echo -n "--- $i: "; cat $i/name; ./input_id $i; done
--- /sys/class/input/input0: Lid Switch
ID_INPUT=1
--- /sys/class/input/input1: Power Button
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input10: Dell WMI hotkeys
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input11: HDA Intel Line In at Ext Left Jack
ID_INPUT=1
--- /sys/class/input/input12: HDA Intel HP Out at Ext Left Jack
ID_INPUT=1
--- /sys/class/input/input13: DualPoint Stick
ID_INPUT=1
ID_INPUT_MOUSE=1
--- /sys/class/input/input14: AlpsPS/2 ALPS DualPoint TouchPad
ID_INPUT=1
ID_INPUT_MOUSE=1
ID_INPUT_TOUCHPAD=1
--- /sys/class/input/input2: Sleep Button
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input3: Macintosh mouse button emulation
ID_INPUT=1
ID_INPUT_MOUSE=1
--- /sys/class/input/input4: AT Translated Set 2 keyboard
ID_INPUT=1
ID_INPUT_KEY=1
ID_INPUT_KEYBOARD=1
--- /sys/class/input/input5: Video Bus
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input6: Video Bus
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input7: HID 05f3:0007
ID_INPUT=1
ID_INPUT_KEY=1
ID_INPUT_KEYBOARD=1
##### ^^^ This is an USB keyboard, so this is correct.
--- /sys/class/input/input8: HID 05f3:0007
ID_INPUT=1
ID_INPUT_KEY=1
--- /sys/class/input/input9: Logitech USB-PS/2 Optical Mouse
ID_INPUT=1
ID_INPUT_MOUSE=1


[1] http://people.canonical.com/~pitti/tmp/66-xorg-synaptics.rules
[2] http://people.canonical.com/~pitti/tmp/input_id.c
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)

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