pwm: Add a driver for Chrome OS EC PWM
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>
diff --git a/include/cros_ec.h b/include/cros_ec.h
index eddc23d..9396b4d 100644
--- a/include/cros_ec.h
+++ b/include/cros_ec.h
@@ -513,6 +513,19 @@
int cros_ec_battery_cutoff(struct udevice *dev, uint8_t flags);
/**
+ * cros_ec_set_pwm_duty() - Set duty cycle of a generic pwm
+ *
+ * Note that duty value needs to be passed to the EC as a 16 bit number
+ * for increased precision.
+ *
+ * @param dev CROS-EC device
+ * @param index Index of the pwm
+ * @param duty Desired duty cycle, in 0..EC_PWM_MAX_DUTY range.
+ * @return 0 if OK, -ve on error
+ */
+int cros_ec_set_pwm_duty(struct udevice *dev, uint8_t index, uint16_t duty);
+
+/**
* cros_ec_read_limit_power() - Check if power is limited by batter/charger
*
* Sometimes the battery is low and / or the device is connected to a charger