fan-control.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#define HWMON_BASE "/sys/class/hwmon"

#define GPU_HWMON "hwmon0" // amdgpu
#define GPU_TEMP_TEMP "temp1" // no name
#define GPU_FAN_PWM "pwm1"

#define CHIPSET_HWMON "hwmon1" // nct6791
#define SYSTIN_TEMP_TEMP "temp1" // "SYSTIN"
#define CPUTIN_TEMP_TEMP "temp2" // "CPUTIN"
#define PECI_TEMP_TEMP "temp7" // "PECI Agent 0"
#define CPU_FAN_PWM "pwm2"
#define CHA1_FAN_PWM "pwm5"
#define CHA2_FAN_PWM "pwm4"

// Unused
#define CPU_HWMON "hwmon2" // coretemp
#define CPU_TEMP_TEMP "temp1" // "Physical id 0"

const char* gpu_temp_temp_filename = HWMON_BASE "/" GPU_HWMON "/" GPU_TEMP_TEMP "_input";
const char* cpu_temp_temp_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CPUTIN_TEMP_TEMP "_input";
const char* core_temp_temp_filename = HWMON_BASE "/" CHIPSET_HWMON "/" PECI_TEMP_TEMP "_input";
const char* sys_temp_temp_filename = HWMON_BASE "/" CHIPSET_HWMON "/" SYSTIN_TEMP_TEMP "_input";

const char* gpu_fan_pwm_filename = HWMON_BASE "/" GPU_HWMON "/" GPU_FAN_PWM;
const char* cpu_fan_pwm_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CPU_FAN_PWM;
const char* cha1_fan_pwm_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CHA1_FAN_PWM;
const char* cha2_fan_pwm_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CHA2_FAN_PWM;

int gpu_temp = -1;
int cpu_temp = -1;
int sys_temp = -1;

int gpu_state = 0;
int cpu_state = 0;
int sys_state = 0;

int gpu_pwm_old = -1;
int cpu_pwm_old = -1;
int cha1_pwm_old = -1;
int cha2_pwm_old = -1;

int gpu_pwm = -1;
int cpu_pwm = -1;
int cha1_pwm = -1;
int cha2_pwm = -1;

void write_number(const char* filename, int num)
{
	char buf[32];
	snprintf(buf, sizeof buf, "%d", num);

	FILE* fh = fopen(filename, "wt");

	if (fh)
	{
		fputs(buf, fh);
		fclose(fh);
	}
}

int read_number(const char* filename)
{
	char buf[32];
	FILE* hwmon = fopen(filename, "r");

	int num = -1;

	if (hwmon != NULL && fgets(buf, 32, hwmon))
	{
		sscanf(buf, "%d", &num);
		fclose(hwmon);
	}

	return num;
}

void enable_control()
{
	const char* gpu_fan_pwm_enable_filename = HWMON_BASE "/" GPU_HWMON "/" GPU_FAN_PWM "_enable";
	const char* cpu_fan_pwm_enable_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CPU_FAN_PWM "_enable";
	const char* cha1_fan_pwm_enable_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CHA1_FAN_PWM "_enable";
	const char* cha2_fan_pwm_enable_filename = HWMON_BASE "/" CHIPSET_HWMON "/" CHA2_FAN_PWM "_enable";

	write_number(gpu_fan_pwm_enable_filename, 1);
	write_number(cpu_fan_pwm_enable_filename, 1);
	write_number(cha1_fan_pwm_enable_filename, 1);
	write_number(cha2_fan_pwm_enable_filename, 1);
}

void gather_inputs(int tick)
{
	(void)tick;

	gpu_temp = read_number(gpu_temp_temp_filename);
	cpu_temp = read_number(cpu_temp_temp_filename);
	sys_temp = read_number(sys_temp_temp_filename);
}

void state_rule(const int* temp_in, int* state_inout, int hyst)
{
	int temp = *temp_in;
	int state = *state_inout;

	if (temp >= state + hyst)
		*state_inout = temp / hyst * hyst;

	if (temp > 0 && temp < state - hyst)
		*state_inout = temp / hyst * hyst;
}

#define GPU_FAN_IDLE 0
#define GPU_FAN_LOW 80
#define GPU_FAN_MID 100
#define GPU_FAN_HIGH 120

#define CPU_FAN_IDLE 60
#define CPU_FAN_LOW 120
#define CPU_FAN_MID 155
#define CPU_FAN_HIGH 220

#define CHA1_FAN_IDLE 100
#define CHA1_FAN_LOW 140
#define CHA1_FAN_MID 180
#define CHA1_FAN_HIGH 220

#define CHA2_FAN_IDLE 100
#define CHA2_FAN_LOW 100
#define CHA2_FAN_MID 150
#define CHA2_FAN_HIGH 255

int x_gpu_fan_on = 0;

int max(int a, int b)
{
	return (a > b) ? a : b;
}

void thermal_rules(int tick)
{
	(void)tick;

	state_rule(&gpu_temp, &gpu_state, 1000);
	state_rule(&cpu_temp, &cpu_state, 5000);
	state_rule(&sys_temp, &sys_state, 2000);

	int adj_gpu_state = gpu_state - sys_state;

	// GPU fan
	if (adj_gpu_state >= 15000 || gpu_state >= 45000)
		gpu_pwm = GPU_FAN_LOW + (max(adj_gpu_state - 15000, gpu_state - 44000) / 1000) * 5;
	else if (adj_gpu_state >= 10000 || gpu_state >= 45000)
		gpu_pwm = GPU_FAN_LOW;
	else if (x_gpu_fan_on)
		gpu_pwm = GPU_FAN_LOW;
	else
		gpu_pwm = GPU_FAN_IDLE;

	// Extra hacky logic to disable GPU fan at 30C rather than 40C
	if (!x_gpu_fan_on)
	{
		if (gpu_pwm != GPU_FAN_IDLE)
			x_gpu_fan_on = 1;
	}
	else
	{
		if (adj_gpu_state <= 5000)
		{
			gpu_pwm = GPU_FAN_IDLE;
			x_gpu_fan_on = 0;
		}
	}

	x_gpu_fan_on = (gpu_pwm != GPU_FAN_IDLE);

	// CPU fan
	if (cpu_state >= 65000)
		cpu_pwm = 255;
	else if (cpu_state >= 55000)
		cpu_pwm = CPU_FAN_HIGH;
	else if (cpu_state >= 50000)
		cpu_pwm = CPU_FAN_MID;
	else if (cpu_state >= 45000)
		cpu_pwm = CPU_FAN_LOW;
	else
		cpu_pwm = CPU_FAN_IDLE;

	// CHA1 fan
	if (cpu_state >= 45000)
		cha1_pwm = CHA1_FAN_HIGH;
	else if (cpu_state >= 40000)
		cha1_pwm = CHA1_FAN_MID;
	else if (cpu_state >= 35000)
		cha1_pwm = CHA1_FAN_LOW;
	else
		cha1_pwm = CHA1_FAN_IDLE;

	// CHA2 fan
	if (sys_state >= 44000 || cha1_pwm >= CHA1_FAN_HIGH)
		cha2_pwm = CHA2_FAN_HIGH;
	else if (sys_state >= 40000 || gpu_state >= 50000 || cha1_pwm >= CHA1_FAN_MID)
		cha2_pwm = CHA2_FAN_MID;
	else if (sys_state >= 36000 || gpu_pwm >= GPU_FAN_LOW || cpu_state >= 40000)
		cha2_pwm = CHA2_FAN_LOW;
	else
		cha2_pwm = CHA2_FAN_IDLE;

	if (cha2_pwm >= CHA2_FAN_HIGH && cha1_pwm <= CHA1_FAN_MID)
		cha1_pwm = CHA1_FAN_MID;

	if (cha2_pwm >= CHA2_FAN_MID && cha1_pwm <= CHA1_FAN_LOW)
		cha1_pwm = CHA1_FAN_LOW;
}

void apply_pwm(int tick)
{
	(void)tick;

	if (gpu_pwm != gpu_pwm_old)
	{
		write_number(gpu_fan_pwm_filename, gpu_pwm);
		gpu_pwm_old = gpu_pwm;
	}

	if (cpu_pwm != cpu_pwm_old)
	{
		write_number(cpu_fan_pwm_filename, cpu_pwm);
		cpu_pwm_old = cpu_pwm;
	}

	if (cha1_pwm != cha1_pwm_old)
	{
		write_number(cha1_fan_pwm_filename, cha1_pwm);
		cha1_pwm_old = cha1_pwm;
	}

	if (cha2_pwm != cha2_pwm_old)
	{
		write_number(cha2_fan_pwm_filename, cha2_pwm);
		cha2_pwm_old = cha2_pwm;
	}
}

int main()
{
	enable_control();

	for (int tick = 0; ; ++tick)
	{
		gather_inputs(tick);
		thermal_rules(tick);
		apply_pwm(tick);

		usleep(1000000);
	}

	return 0;
}