mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-15 07:43:07 +00:00
1b9ee2882e
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>
23 lines
564 B
Text
23 lines
564 B
Text
PWM controlled by ChromeOS EC
|
|
|
|
Google's ChromeOS EC PWM is a simple PWM attached to the Embedded Controller
|
|
(EC) and controlled via a host-command interface.
|
|
|
|
An EC PWM node should be only found as a sub-node of the EC node (see
|
|
doc/device-tree-bindings/misc/cros-ec.txt).
|
|
|
|
Required properties:
|
|
- compatible: Must contain "google,cros-ec-pwm"
|
|
- #pwm-cells: Should be 1. The cell specifies the PWM index.
|
|
|
|
Example:
|
|
cros-ec@0 {
|
|
compatible = "google,cros-ec-spi";
|
|
|
|
...
|
|
|
|
cros_ec_pwm: ec-pwm {
|
|
compatible = "google,cros-ec-pwm";
|
|
#pwm-cells = <1>;
|
|
};
|
|
};
|