/*
A Project of Andrea Cioni

Title:     Fan Daemon (FanD)

Author:    Andrea Cioni (andreacioni)
           cioni95@gmail.com

Copyright: 	
	Copyright (c) 2017 Andrea Cioni <cioni95@gmail.com>
	https://github.com/dweeber/WiFi_Check

Purpose:
	Simple utility program for GNU/Linux systems to control a fan motor of your miniPC (UDOO,Raspberry Pi,Orange Pi,etc) through a PWM signal.

Compile:
	gcc -std=gnu99 fand.c -o fand

Launch:
	fand <frequency of the PWM signal> <sleep seconds between temperature checks> <min temp in Celsius> <max temp in Celsius> <min dc percent> <max dc percent>
			
Example usage: 
	./fand 2 3 20 30 10 100

*/

#include<stdio.h>
#include<stdbool.h>
#include<stdlib.h>
#include<unistd.h>
#include<signal.h>

#define HELLO_BANNER "Fan Daemon"
#define VERSION "(0.2v)"

#define BASE_PATH "/sys/class/pwm/pwmchip0/"

#define EXPORT_PATH BASE_PATH "pwm0/"

static volatile bool go = true;

struct console_args {
	unsigned long period;
	unsigned long sleep_timeout;
	unsigned long min_temp;
	unsigned long max_temp;
	unsigned short min_percent_dc;
	unsigned short max_percent_dc;
};

bool export() {
	return system("echo 0 > " BASE_PATH "export") == 0;
}

bool unexport() {
	return system("echo 0 > " BASE_PATH "unexport") == 0;
}

bool enable(bool enable) {
	if(enable)
		return system("echo 1 > " EXPORT_PATH "enable") == 0;
	else
		return system("echo 0 > " EXPORT_PATH "enable") == 0;
}

bool setup(unsigned long period) {
	char buf[1024];
	return (sprintf(buf,"echo %lu > " EXPORT_PATH "period",period) != 0) && (system(buf) == 0);
}

bool set_dc(float percent,unsigned long period) {
	char buf[1024];
	percent = (percent>100.0f) ? 100.0f : percent;
	unsigned long dc_ns = (percent/100)*period;
	dc_ns = (dc_ns >= period) ? (period-1) : dc_ns;
	printf("Percent: %0.1f %%, DC: %lu/%lu\n",percent,dc_ns,period);
	
	return (sprintf(buf,"echo %lu > " EXPORT_PATH "duty_cycle",dc_ns) != 0) && (system(buf) == 0);
}

float read_cpu_temp() {
	float ret = -1.0f;
	FILE *fp = popen("/bin/cat /sys/devices/virtual/thermal/thermal_zone0/temp", "r");
	char buf[1024] = {0};
	
	if(fp != NULL) {
		if(fgets(buf,1023,fp) != NULL) {
			
			printf("Temperature read: %s",buf);
			
			if((ret=strtoul(buf,NULL,10)) != 0) {
				ret=ret/1000;
			} else {
				printf("Cannot convert output string\n");
			}
		} else {
			printf("Cannot read CPU temperature from output\n");
		}
		
		pclose(fp);	
	} else {
		printf("Cannot read CPU temperature\n");
	}
		
	return ret;
}

void kill_handler(int sig) {
	printf("Terminating...\n");
	go=false;
}

int run(struct console_args _args) {
	int ret=0;
	
	signal(SIGINT,kill_handler);
	
	while(go) {
		float cpu_temp = read_cpu_temp(),percentdc=0;
		if(cpu_temp > _args.min_temp) {
			float ratio = (cpu_temp-_args.min_temp)/(_args.max_temp - _args.min_temp);
			percentdc = (ratio*(_args.max_percent_dc - _args.min_percent_dc))+_args.min_percent_dc;
			
		}
		
		if(!set_dc(percentdc,_args.period))
			printf("There was an error setting the duty cicle");
		
		sleep(_args.sleep_timeout);
		
		printf("\n");
	}
	
	return ret;
}

bool parse_arguments(int argv, char **argc,struct console_args *_args) {
	bool ret=true;
	if(argv == 7) {
		
		unsigned long ul = strtoul(argc[1],NULL,10);
		if(ul != 0) {
			_args->period = (1.0f/ul)*100000000L;
			printf("Frequency: %lu Hz, Period: %lu s\n",ul,_args->period);
		} else
			ret &= false;
		
		ul = strtoul(argc[2],NULL,10);
		if(ul != 0) {
			_args->sleep_timeout = ul;
			printf("Sleep timeout: %lu s\n",_args->sleep_timeout);
		} else
			ret &= false;
		
		ul = strtoul(argc[3],NULL,10);
		if(ul != 0) {
			_args->min_temp = ul;
			printf("Min temperature: %lu *C\n",_args->min_temp);
		} else
			ret &= false;
		
		ul = strtoul(argc[4],NULL,10);
		if(ul != 0) {
			_args->max_temp = ul;
			printf("Max temperature: %lu *C\n",_args->max_temp);
		} else
			ret &= false;
		
		ul = strtoul(argc[5],NULL,10);
		if(ul != 0) {
			_args->min_percent_dc = (unsigned short) ul;
			printf("Min duty cycle: %i %%\n",_args->min_percent_dc);
		} else
			ret &= false;
		
		ul = strtoul(argc[6],NULL,10);
		if(ul != 0) {
			_args->max_percent_dc = (unsigned short) ul;
			printf("Max duty cycle: %i %%\n",_args->max_percent_dc);
		} else
			ret &= false;
			
	} else
		ret=false;
	
	return ret;
}

int main(int argv, char **argc) {
	int ret = 0;
	struct console_args _args;
	
	printf("%s %s\n",HELLO_BANNER,VERSION);
	
	if(!parse_arguments(argv,argc,&_args)) {
		printf("fand <frequency> <sleep seconds> <min temp> <max temp> <min dc percent> <max dc percent> \n");
		ret = 100;
	} else {
		printf("Exporting...");
		if(export()) {
			printf("OK!\n");
			
			printf("Setupping (f=%lu)...",_args.period);
			if(setup(_args.period)) {
				printf("OK!\n");
				
				printf("Enabling...");
				if(enable(true)) {
					printf("OK!\n");
					
					ret = run(_args);
					
					printf("Disabling...");
					if(enable(false)) {
						printf("OK!\n");
					} else {
						printf("FAIL!\n");
						ret = 4;
					}
				} else {
					printf("FAIL!\n");
					ret=3;
				}
				
			} else {
				printf("FAIL!\n");
				ret=2;
			}
		} else {
			printf("FAIL!\n");
			ret=1;
		}
		
		printf("Unexporting...");
		if(unexport()) {
			printf("OK!\n");
		} else {
			printf("FAIL!\n");
		}
		
	}
	
	return ret;
}