Re: logitech-djdevice and /sys

On Thu, 22 Mar 2012, Arkadiusz Miśkiewicz wrote:

Hi,

I'm detecting usb keyboards from shell using this simple script:

for i in /sys/class/input/input*; do
                [ ! -f $i/device/bInterfaceClass -o ! -f $i/device/bInterfaceProtocol ] && continue
                bInterfaceClass=$(cat $i/device/bInterfaceClass)
                bInterfaceProtocol=$(cat $i/device/bInterfaceProtocol)
                if [ "$bInterfaceClass" = "03" -a "$bInterfaceProtocol" = "01" ]; then
			module=$(readlink $i/device/driver/module)
                        module=$(basename $module)

			echo "found keyboard driven by $module"
		fi
done

but for keyboards hidden behind logitech unifying receiver there seem to 
be no such information in /sys.

Any ideas on how I can detect such keyboards via /sys or other
scriptable method?

(note that I'm interested only in "regular" keyboards, so single buttons
and some other devices are not interesting)

dmesg:

[130816.672862] usb 6-2: new full-speed USB device number 4 using uhci_hcd
[130816.856173] usb 6-2: New USB device found, idVendor=046d, idProduct=c52b
[130816.856183] usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[130816.856190] usb 6-2: Product: USB Receiver
[130816.856195] usb 6-2: Manufacturer: Logitech
[130816.868751] logitech-djreceiver 0003:046D:C52B.000F: hiddev0,hidraw2: USB HID v1.11 Device [Logitech USB Receiver] on usb-0000:00:1d.0-2/input2
[130816.878201] input: Logitech Unifying Device. Wireless PID:4004 as /devices/pci0000:00/0000:00:1d.0/usb6/6-2/6-2:1.2/0003:046D:C52B.000F/input/input14
[130816.878717] logitech-djdevice 0003:046D:C52B.0010: input,hidraw3: USB HID v1.11 Keyboard [Logitech Unifying Device. Wireless PID:4004] on usb-0000:00:1d.0-2:1

I suggest you inspect all available input devices using EVIOCGBIT ioctl() 
instead, querying the device capabilities (and looking namely on the 
EV_KEY capabilities).

Alternatively, you can find this information prepared for you in 
/proc/bus/input/devices.

If you really want to restrict yourself to USB keyboards, you'll have to 
inspect 'Phys' as well. This you can do via EVIOCGPHYS ioctl() or look 
into procfs as well.

-- 
Jiri Kosina
SUSE Labs
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