xref: /freebsd/sys/contrib/device-tree/Bindings/hwmon/pwm-fan.txt (revision 5def4c47d4bd90b209b9b4a4ba9faec15846d8fd)
1Bindings for a fan connected to the PWM lines
2
3Required properties:
4- compatible	: "pwm-fan"
5- pwms		: the PWM that is used to control the PWM fan
6- cooling-levels      : PWM duty cycle values in a range from 0 to 255
7			which correspond to thermal cooling states
8
9Optional properties:
10- fan-supply		: phandle to the regulator that provides power to the fan
11- interrupts		: This contains an interrupt specifier for each fan
12			  tachometer output connected to an interrupt source.
13			  The output signal must generate a defined number of
14			  interrupts per fan revolution, which require that
15			  it must be self resetting edge interrupts. See
16			  interrupt-controller/interrupts.txt for the format.
17- pulses-per-revolution : define the number of pulses per fan revolution for
18			  each tachometer input as an integer (default is 2
19			  interrupts per revolution). The value must be
20			  greater than zero.
21
22Example:
23	fan0: pwm-fan {
24		compatible = "pwm-fan";
25		#cooling-cells = <2>;
26		pwms = <&pwm 0 10000 0>;
27		cooling-levels = <0 102 170 230>;
28	};
29
30	thermal-zones {
31		cpu_thermal: cpu-thermal {
32			     thermal-sensors = <&tmu 0>;
33			     polling-delay-passive = <0>;
34			     polling-delay = <0>;
35			     trips {
36					cpu_alert1: cpu-alert1 {
37						    temperature = <100000>; /* millicelsius */
38						    hysteresis = <2000>; /* millicelsius */
39						    type = "passive";
40					};
41			     };
42			     cooling-maps {
43					map0 {
44						    trip = <&cpu_alert1>;
45						    cooling-device = <&fan0 0 1>;
46					};
47			     };
48		};
49
50Example 2:
51	fan0: pwm-fan {
52		compatible = "pwm-fan";
53		pwms = <&pwm 0 40000 0>;
54		fan-supply = <&reg_fan>;
55		interrupt-parent = <&gpio5>;
56		interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
57		pulses-per-revolution = <2>;
58	};
59
60Example 3:
61	fan0: pwm-fan {
62		compatible = "pwm-fan";
63		pwms = <&pwm1 0 25000 0>;
64		interrupts-extended = <&gpio1 1 IRQ_TYPE_EDGE_FALLING>,
65			<&gpio2 5 IRQ_TYPE_EDGE_FALLING>;
66		pulses-per-revolution = <2>, <1>;
67	};
68