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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
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Google's ChromeOS EC PWM is a simple PWM attached to the Embedded Controller
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(EC) and controlled via a host-command interface.
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An EC PWM node should be only found as a sub-node of the EC node (see
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doc/device-tree-bindings/misc/cros-ec.txt).
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Required properties:
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- compatible: Must contain "google,cros-ec-pwm"
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- #pwm-cells: Should be 1. The cell specifies the PWM index.
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Example:
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cros-ec@0 {
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compatible = "google,cros-ec-spi";
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...
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cros_ec_pwm: ec-pwm {
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compatible = "google,cros-ec-pwm";
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#pwm-cells = <1>;
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};
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};
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