Add function needed to generate ACPI backlight control SSDT, along with
Kconfig values for accessing the registers.
Tested by adding gfx register on system76/lemp11. Backlight controls
work on Windows 10 and Linux 6.1.
Change-Id: I1cc33bf0121ff44aea68a7e3615c5e58e2ab6ce2
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69076
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
c6529c7c0a