chrome ec: Add ACPI Device for ALS if enabled

The EC can export ALS information if the sensor is attached
to it directly rather than to the host.  This adds a basic
ACPI ALS device and implements the required information.

The kernel does not use the _ALR tuple set but it is required
by the ACPI spec so this just adds the sample two point
response curve defined in ACPI 5.0 section 9.2.5.

The EC does not currently send events for lux value changes so
a polling interval of 1 second is defined.

BUG=chrome-os-partner:24208
BRANCH=None
TEST=build and boot on samus, add acpi-als driver to the kernel
and read /sys/bus/iio/devices/iio:device0/in_illuminance_raw

Original-Change-Id: Id29b72a68aa21c1a7c71d5f87223ac010cef0377
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/203743
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit 81f44b33b87a6ee3079b8ef6efffacd0eeb0283f)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I5a0ccd30e8b453675beaf7d0363dbfa162bd5b3f
Reviewed-on: http://review.coreboot.org/8132
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

0 files changed, 0 insertions, 0 deletions