1_rock64_fan_dts.patch

diff --git a/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts b/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
index 3bef1f39b..87e1c2dd1 100644
--- a/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
@@ -19,6 +19,36 @@ chosen {
 		stdout-path = "serial2:1500000n8";
 	};
 
+	gpio_fan_cool: gpio_fan {
+		#cooling-cells = <2>;
+		compatible = "gpio-fan";
+		gpios = <
+			&gpio0 RK_PA0 GPIO_ACTIVE_LOW
+			&gpio3 RK_PA4 GPIO_ACTIVE_LOW
+			&gpio3 RK_PA5 GPIO_ACTIVE_LOW
+			&gpio3 RK_PA6 GPIO_ACTIVE_LOW
+		>;
+		gpio-fan,speed-map = <
+			0 0
+			333 1
+			666 2
+			1000 3
+			1333 4
+			1666 5
+			2000 6
+			2333 7
+			2666 8
+			3000 9
+			3333 10
+			3666 11
+			4000 12
+			4333 13
+			4666 14
+			5000 15
+		>;
+		status = "okay";
+	};
+
 	gmac_clkin: external-gmac-clock {
 		compatible = "fixed-clock";
 		clock-frequency = <125000000>;
@@ -108,6 +138,34 @@ spdif_dit: spdif-dit {
 	};
 };
 
+&soc_thermal {
+	trips {
+		fan_point0: fan-point0 {
+			temperature = <40000>;
+			hysteresis = <2000>;
+			type = "active";
+		};
+		fan_point1: fan-point1 {
+			temperature = <45000>;
+			hysteresis = <2000>;
+			type = "active";
+		};
+	};
+
+	cooling-maps {
+		map1 {
+			trip = <&fan_point1>;
+			cooling-device =
+				<&gpio_fan_cool 3 15>;
+		};
+		map2 {
+			trip = <&fan_point0>;
+			cooling-device =
+				<&gpio_fan_cool 0 0>;
+		};
+	};
+};
+
 &analog_sound {
 	status = "okay";
 };

2_gpiopwm.ino

void setup() {
  pinMode(4, INPUT_PULLUP);
  pinMode(5, INPUT_PULLUP);
  pinMode(6, INPUT_PULLUP);
  pinMode(7, INPUT_PULLUP);
  pinMode(14, OUTPUT);
}

void loop() {
  // pwm every 25 kHz
  // 40000 ns = 40 microseconds
  int val = 0;
  val |= int(digitalRead(4) == 0);
  val |= int(digitalRead(5) == 0) << 1;
  val |= int(digitalRead(6) == 0) << 2;
  val |= int(digitalRead(7) == 0) << 3;
  softPWM(14, float(val) / float(0b1111));
}

void softPWM(int pin, float dutycycle) {
  int ontime = int(dutycycle * 40.0 + 0.5);
  int offtime = 40 - ontime;
  if(ontime > 0) {
    digitalWrite(pin, HIGH);
    delayMicroseconds(ontime);
  }
  if(offtime > 0) {
    digitalWrite(pin, LOW);
    delayMicroseconds(offtime);
  }
}