fan-control

#!/usr/bin/env python3
""" Fan Control for raspberry pi 5 - tested on Raspberry Pi 5 Model B, kernel 6.8.0 """
from enum import Enum
import time
import os
import sys

class FanSpeed(Enum):
	""" Symbolics for fan speed input """
	OFF = 0
	LOW = 1
	MEDIUM = 2
	HIGH = 3
	FULL = 4

class Fan:
	def __init__(self):
		self.fan_path = "/sys/class/thermal/cooling_device0/cur_state"
		self.temp_path = "/sys/devices/virtual/thermal/thermal_zone0/temp"
		self.ranges = {
			70: FanSpeed.FULL,
			65: FanSpeed.HIGH,
			60: FanSpeed.MEDIUM,
			55: FanSpeed.LOW,
			54: FanSpeed.OFF
		}

	@property
	def speed(self) -> FanSpeed:
		with open(self.fan_path) as f:
			speed = int(f.read().strip())
		return FanSpeed(speed)

	def set_speed(self, speed: FanSpeed):
		with open(self.fan_path, "w") as f:
			f.write(str(speed.value))
		return self

	def get_temp(self) -> float:
		with open(self.temp_path, "r") as f:
			data = f.read().strip()
		return float(data) / 1000

	def adjust_for_temp(self):
		temp = self.get_temp()
		cspeed = self.speed
		speed = cspeed
		for level, spd in self.ranges.items():
			if temp >= level:
				speed = spd
				#print(temp,level,spd)
				break

		self.set_speed(speed)

def main():
	check_paths = [	"/sys/class/thermal/cooling_device0/cur_state",
					"/sys/devices/virtual/thermal/thermal_zone0/temp"]
	fail = False
	for p in check_paths:
		if not os.path.exists(p):
			print(f"Cannot find control interface at {p}",file=sys.stderr)
			fail = True
	if fail:
		print('Required control interfaces are not present. Please ensure any required kernel modules are loaded.',file=sys.stderr)
		sys,exit(-1)

	fan = Fan()
	if os.getuid() != 0:
		print("fan control must be run as root",file=sys.stderr)
		sys.exit(-13)
	print("Fan control started")
	while True:
		try:
			fan.adjust_for_temp()
		except Exception as e:
			print(f'adjust-for-temp: {e}',file=sys.stderr)

		time.sleep(2)


if __name__ == "__main__":
	main()