Comment 0 for bug 1347776

Some ARM board uses GPIO gpio_key.12 for power control (key=116). The proposed patch adds entry to logind's 70-power-switch.rules to initiate soft shutdown of the cartridge from ilo.

Here is the udevadm output for /dev/input/event0

sudo udevadm info --query=all --name=/dev/input/event0 --attribute-walk

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/soc.3/gpio_keys.12/input/input0/event0':
    KERNEL=="event0"
    SUBSYSTEM=="input"
    DRIVER==""

  looking at parent device '/devices/soc.3/gpio_keys.12/input/input0':
    KERNELS=="input0"
    SUBSYSTEMS=="input"
    DRIVERS==""
    ATTRS{name}=="gpio_keys.12"
    ATTRS{phys}=="gpio-keys/input0"
    ATTRS{uniq}==""
    ATTRS{properties}=="0"

  looking at parent device '/devices/soc.3/gpio_keys.12':
    KERNELS=="gpio_keys.12"
    SUBSYSTEMS=="platform"
    DRIVERS=="gpio-keys"
    ATTRS{keys}=="116"
    ATTRS{switches}==""
    ATTRS{disabled_keys}==""
    ATTRS{disabled_switches}==""

  looking at parent device '/devices/soc.3':
    KERNELS=="soc.3"
    SUBSYSTEMS=="platform"
    DRIVERS==""

Regarding the possibility of gpio_key.12 being used by other systems to map to some other trigger, I put in the check that the gpio_key.12 is associated with power control (keys=116). '116' is supposedly linux generic power control in DTS. There is no uniq idSystem or idVendor for device /dev/input/event0 as you can see from udevadm output, therefore I tried to use the best available combination as a safety check. This patch will enable power control for any system vendor (Other than the one the patch in intended for) that describes in DTS, the trigger gpio_key.12 as power control (116).