This PWM is used in rk3399-gru-bob and rk3399-gru-kevin to control
the display brightness. We can only change the duty cycle, so on
set_config() we just try to match the duty cycle that dividing duty_ns
by period_ns gives us. To disable, we set the duty cycle to zero while
keeping the old value for when we want to re-enable it.
The cros_ec_set_pwm_duty() function is taken from Depthcharge's
cros_ec_set_bl_pwm_duty() but modified to use the generic pwm type.
The driver itself is very loosely based on rk_pwm.c for the general pwm
driver structure.
The devicetree binding file is from Linux, before it was converted to
YAML at 5df5a577a6b4 ("dt-bindings: pwm: Convert google,cros-ec-pwm.txt
to YAML format") in their repo.
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Device Tree Bindings Staging Area
=================================
This directory contains device tree bindings for U-Boot.
These follow along with Linux kernel bindings, with a few additions. By
adding the files here, U-Boot patches can clearly show thees additions.
This makes it easier for device tree people to review these additions in
patches sent to the U-Boot mailing list.
The intent IS to commit these files to U-Boot. Hopefully at some point
the files will be stored in another repo (shared with Linux) which is
brought in as needed. Changes here are intended to mirror changes in the
Linux Documentation/devicetree/bindings/ directory.
sjg@chromium.org
17-Jan-12
1b9ee2882e