/*********************************************************************************
 *      Copyright:  (C) 2021 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  gpiod.c
 *    Description:  This file is used to control a pin GPIO output by libgpiod 
 *
 *     pi@raspberrypi:~ $ gpio readall show BCM and wPi pinmap  
 *
 *                 
 *        Version:  1.0.0(2021/01/23)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "2021/01/23 12:13:26"
 *                 
 ********************************************************************************/

#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 <gpiod.h>

void gpiod_ctxless_cb(void *data)
{
       	sleep(1);
}

int main(int argc, char *argv[])
{
       	struct gpiod_chip      *chip;
	struct gpiod_line      *line;
	int                     bcm_pin;
	int                     level;

	if( argc != 3 )
	{
		printf("  Usage: sudo %s [BCM Pin number] [1/0]\n", argv[0]);
		printf("example, turn BCM Pin #6 lowlevel : sudo %s 6 0\n", argv[0]);
		printf("example, turn BCM Pin #6 highlevel: sudo %s 6 1\n", argv[0]);
	}

	bcm_pin = atoi(argv[1]);
	level = atoi(argv[2]);
#if 0
	if( level )
	       	gpiod_ctxless_set_value("gpiochip0", bcm_pin, 1, false, "led", gpiod_ctxless_cb, NULL);
       	else
	       	gpiod_ctxless_set_value("gpiochip0", bcm_pin, 0, false, "led", gpiod_ctxless_cb, NULL);
#else
	chip = gpiod_chip_open_by_name("gpiochip0");
	if( !chip )
	{
		printf("gpiod open chip failure, maybe you need running as root\n");
		exit(1);
	}

	line = gpiod_chip_get_line(chip, bcm_pin);
	if( !line )
	{
		printf("gpiod get line for BCM pin [#%d] failure\n", bcm_pin);
		exit(1);
	}

	gpiod_line_request_output(line, "led", 1);

	printf("set BCM pin #%d as %s level\n", bcm_pin, level?"high":"low");

	if( level )
	{
	       	gpiod_line_set_value(line, 1);
	}
	else
	{
	       	gpiod_line_set_value(line, 0);
	}

	sleep(1); /* must add sleep here, or it will not take effect */

	gpiod_line_release(line);
	gpiod_chip_close(chip);
#endif

        return 0;
}