linux/Documentation/devicetree/bindings/hwmon/pwm-fan.txt

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Bindings for a fan connected to the PWM lines
Required properties:
- compatible : "pwm-fan"
- pwms : the PWM that is used to control the PWM fan
- cooling-levels : PWM duty cycle values in a range from 0 to 255
which correspond to thermal cooling states
Optional properties:
- fan-supply : phandle to the regulator that provides power to the fan
- interrupts : This contains a single interrupt specifier which
describes the tachometer output of the fan as an
interrupt source. The output signal must generate a
defined number of interrupts per fan revolution, which
require that it must be self resetting edge interrupts.
See interrupt-controller/interrupts.txt for the format.
- pulses-per-revolution : define the tachometer pulses per fan revolution as
an integer (default is 2 interrupts per revolution).
The value must be greater than zero.
Example:
fan0: pwm-fan {
compatible = "pwm-fan";
#cooling-cells = <2>;
pwms = <&pwm 0 10000 0>;
cooling-levels = <0 102 170 230>;
};
thermal-zones {
cpu_thermal: cpu-thermal {
thermal-sensors = <&tmu 0>;
polling-delay-passive = <0>;
polling-delay = <0>;
trips {
cpu_alert1: cpu-alert1 {
temperature = <100000>; /* millicelsius */
hysteresis = <2000>; /* millicelsius */
type = "passive";
};
};
cooling-maps {
map0 {
trip = <&cpu_alert1>;
cooling-device = <&fan0 0 1>;
};
};
};
Example 2:
fan0: pwm-fan {
compatible = "pwm-fan";
pwms = <&pwm 0 40000 0>;
fan-supply = <&reg_fan>;
interrupt-parent = <&gpio5>;
interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
pulses-per-revolution = <2>;
};