udev: Allow quirks for ACPI input accelerometers
The existing accelerometer rules only support IIO devices, however
iio-sensor-proxy can also work with accelerometers made available
through the input (evdev) subsystem.
In this case I am working with an accelerometer input device backed by an
ACPI driver for which the hierarchy is:
-
ACCE0001 (ACPI device)
-> input8
-> event7
We want the mount matrix (from hwdb) to be applied to both input8 and
event7. However, to match in 60-sensor.hwdb, we need to be working
with the modalias of the parent device (
ACCE0001), and it is tricky
to access that when processing the input8 device which has it's own
modalias.
Instead of working directly with modalias, this ACPI-specific rule
uses the "hid" attribute to reconstruct the ACPI modalias. Since input
and event devices do not provide a hid attribute we will always get this
from the ACPI parent.
The modalias is constructed according to the definition in the kernel's
Documentation/acpi/namespace.txt and create_pnp_modalias(). We will only
use the first _CID/_HID value available, i.e. in some cases we will only
reconstruct the first part of the modalias, but that should be enough
granularity for our needs.