/*********************************************************************************
 *      Copyright:  (C) 2021 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  pwm.c
 *    Description:  This file is used to control PWM buzzer/Led
 *
 * Pin connection:
 *               PWM Module              Raspberry Pi Board
 *                  VCC       <----->      5V
 *                 buzzer     <----->      #Pin32(BCM GPIO12)
 *                  Led       <----->      #Pin33(BCM GPIO13)
 *                  GND       <----->      GND
 *
 * /boot/config.txt:
 *
 *          dtoverlay=pwm,pin=12,func=4 (Buzzer)
 *          dtoverlay=pwm,pin=13,func=4 (Led)
 *
 ********************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <getopt.h>
#include <libgen.h>

#include "logger.h"
#include "util_proc.h"
#include "pwm.h"

/* check PWM $channel export or not */
int check_pwm(int channel)
{
	char          path[256];

	/* check /sys/class/pwm/pwmchip0/pwmN exist or not */
	snprintf(path, sizeof(path), "%s/pwm%d", PWMCHIP_PATH, channel);
	return access(path, F_OK) ? 0 : 1;
}

/* export($export=1)/unexport($export=0) PWM $channel */
int export_pwm(int channel, int export)
{
	int           fd;
	char          buf[32];
	char          path[256];

	if( export && check_pwm(channel) )
		return 0; /* export already when export  */
	else if( !export && !check_pwm(channel) )
		return 0; /* unexport already when unexport  */

	/* export PWM channel by echo N > /sys/class/pwm/pwmchip0/export */
	snprintf(path, sizeof(path), "%s/%s", PWMCHIP_PATH, export?"export":"unexport");
	if( (fd=open(path, O_WRONLY)) < 0 )
	{
		log_error("open '%s' failed: %s\n", path, strerror(errno));
		return -3;
	}

	snprintf(buf, sizeof(buf), "%d", channel);
	write(fd, buf, strlen(buf));

	msleep(100);

	if( export && check_pwm(channel) )
		return 0; /* export already when export  */
	else if( !export && !check_pwm(channel) )
		return 0; /* unexport already when unexport  */

	return -4;
}

/* configure PWM $channel */
int config_pwm(int channel, int freq, int duty) 
{
	int           fd;
	char          buf[32];
	char          path[256];
	int           period;
	int           duty_cycle;

	if( !check_pwm(channel) )
		return -2;

	/* open PWM period file and write period in ns */
	snprintf(path, sizeof(path), "%s/pwm%d/period", PWMCHIP_PATH, channel);
	if( (fd=open(path, O_WRONLY)) < 0 )
	{
		log_error("open '%s' failed: %s\n", path, strerror(errno));
		return -3;
	}
	period = 1000000000/freq;
	snprintf(buf, sizeof(buf), "%d", period);
	write(fd, buf, strlen(buf));

	/* open PWM duty_cycle file and write duty */
	snprintf(path, sizeof(path), "%s/pwm%d/duty_cycle", PWMCHIP_PATH, channel);
	if( (fd=open(path, O_WRONLY)) < 0 )
	{
		log_error("open '%s' failed: %s\n", path, strerror(errno));
		return -3;
	}
	duty_cycle = (period*duty) / 100;
	snprintf(buf, sizeof(buf), "%d", duty_cycle);
	write(fd, buf, strlen(buf));

	return 0;
}

int init_pwm(int channel, int freq, int duty)
{
	int           rv;
	char          buf[32];
	char          path[256];

	if( (rv=export_pwm(channel, 1)) )
	{
		log_error("export PWM channel[%d] failed, rv=%d\n", channel, rv);
		return rv; 
	}

	if( (rv=config_pwm(channel, freq, duty)) )
	{
		log_error("config PWM channel[%d] failed, rv=%d\n", channel, rv);
		return rv;
	}

	log_debug("config pwm%d with freq[%d] duty[%d] okay\n", channel, freq, duty);

	return 0;
}

int turn_pwm(int channel, int status)
{
	int           fd;
	char          buf[32];
	char          path[256];

	if( !check_pwm(channel) )
		return -1;

	/* open PWM enable file and enable(1)/disable(0) it */
	snprintf(path, sizeof(path), "%s/pwm%d/enable", PWMCHIP_PATH, channel);
	if( (fd=open(path, O_WRONLY)) < 0 )
	{
		log_error("open '%s' failed: %s\n", path, strerror(errno));
		return -3;
	}
	snprintf(buf, sizeof(buf), "%d", status?1:0);
	write(fd, buf, strlen(buf));

	log_debug("pwm[%d] %s\n", channel, status?"enable":"disable");

	return 0;
}

int term_pwm(int channel)
{
	if( !check_pwm(channel) )
		return 0;

	turn_pwm(channel, DISABLE);
	export_pwm(channel, 0);

	return 0;
}

int turn_beep(int times)
{
	int           rv;

	/* stop beeper beep */
	if(times == 0)
	{
		log_debug("Stop beeper\n");
		term_pwm(CHN_BEEPER);
		return 0;
	}

	rv = init_pwm(CHN_BEEPER, FRQ_BEEPER, 50);
	if(rv < 0)
	{
		log_error("Initial beeper pwm[%d] failed, rv=%d\n", CHN_BEEPER);
		return -2;
	}

	/* turn beeper beep ceaselessly */
	if( times < 0)
	{
		turn_pwm(CHN_BEEPER, ENABLE);
		return 0;
	}

	while( times-- )
	{
		turn_pwm(CHN_BEEPER, ENABLE);
		msleep(800);

		turn_pwm(CHN_BEEPER, DISABLE);
		msleep(800);
	}
	
	term_pwm(CHN_BEEPER);
	return 0;
}