/*
 * Copyright (c) 2015  Sulev-Madis Silber <ketas@si.pri.ee>
 * Copyright (c) 2015  Luiz Otavio O Souza <loos.br@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *
 * Example program to read GPIO IRQ events.
 *
 * Build with:
 * cc -Wall -o gpio-irq-event gpio-irq-event.c -lgpio
 */


#include <sys/types.h>
#include <sys/filio.h>
#include <sys/gpio.h>

#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <libgpio.h>


#define MAXIRQS 32


static gpio_handle_t handle;
static int irq[MAXIRQS], nirqs;
static struct pollfd fds[MAXIRQS];


static void
usage(void)
{
	printf("usage:\n");
	printf("gpio-irq-event [-f /dev/gpioN] [-n] pin_number [pin] [..] [pin]\n");
	exit(1);
}


static void
sig_die(int sig)
{
	int i;
	
	
	for (i = 0; i < nirqs; i++)
	{
		if (fds[i].fd != -1)
		{
			gpio_close(fds[i].fd);
		}
		
		if (gpio_irq_unregister(handle, irq[i]) < 0)
		{
			perror("gpio_irq_unregister");
		}
	}
	
	gpio_close(handle);
	
	printf("\n");
	
	exit(1);
}


static int
read_ev(int fd, char *buf, ssize_t buflen, ssize_t *offset)
{
	ssize_t len;
	struct gpio_irq_event *ev;
	
	
	len = read(fd, buf + *offset, buflen - *offset);
	
	if (len == -1)
	{
		perror("read");
		return len;
	}
	else if (len == 0)
	{
		printf("nothing to read: %d\n", len);
		return len;
	}
	
	ev = (struct gpio_irq_event *)buf;
	*offset = len;
	
	while (*offset >= sizeof(*ev))
	{
		printf("gpiointerrupt ts=%lld.%06ld ts_last=%lld.%06ld pin=%d level=%d\n",
			ev->ev_ts.tv_sec, ev->ev_ts.tv_usec,
			ev->ev_ts_last.tv_sec, ev->ev_ts_last.tv_usec,
			ev->ev_pin,
			ev->ev_level);
		
		ev++;
		*offset -= sizeof(*ev);
	}
	
	if (offset > 0)
	{
		bcopy(buf + len - *offset, buf, *offset);
	}
	
	return 1;
}


static void
poll_irq_ev(struct pollfd *fds, int nfds)
{
	char *buf;
	int i, rv;
	ssize_t buflen, offset;
	
	
	offset = 0;
	buflen = sizeof(struct gpio_irq_event) * 128;
	buf = malloc(buflen);
	
	for (;;)
	{
		rv = poll(fds, nfds, -1);
		
		if (rv == -1)
		{
			perror("poll");
			break;
		}
		else if (rv == 0)
		{
			printf("invalid poll return\n");
			break;
		}
		
		for (i = 0; i < nfds; i++)
		{
			if (fds[i].revents & POLLIN)
			{
				if (read_ev(fds[i].fd, buf, buflen, &offset) <= 0)
				{
					break;
				}
			}
		}
	}
	
	free(buf);
}


static void
read_irq_ev(int fd)
{
	char *buf;
	ssize_t buflen, offset;
	
	
	offset = 0;
	buflen = sizeof(struct gpio_irq_event) * 128;
	buf = malloc(buflen);
	
	for (;;)
	{
		if (read_ev(fd, buf, buflen, &offset) <= 0)
		{
			break;
		}
	}
	
	free(buf);
}


int
main(int argc, char **argv)
{
	char *ctlfile;
	int ch, flags, i;
	unsigned int unit;
	
	
	flags = 0;
	ctlfile = NULL;
	
	while ((ch = getopt(argc, argv, "f:n")) != -1)
	{
		switch (ch)
		{
			case 'f':
				ctlfile = optarg;
				break;
			
			case 'n':
				flags |= O_NONBLOCK;
				break;
			
			default:
				usage();
		}
	}
	
	argc -= optind;
	argv += optind;
	
	if (argc < 1)
	{
		usage();
	}
	
	nirqs = 0;
	
	while (argc > 0 && nirqs < MAXIRQS)
	{
		irq[nirqs] = atoi(argv[0]);
		argc--;
		argv++;
		nirqs++;
	}
	
	if (argc > 0 || nirqs > MAXIRQS)
	{
		printf("too many pins at once, try increase MAXIRQS.\n");
		exit(1);
	}
	
	if (nirqs > 1 && (flags & O_NONBLOCK) == 0)
	{
		printf("multiple pins implies the use of nonblock mode.\n");
		flags |= O_NONBLOCK;
	}
	
	if (flags & O_NONBLOCK)
	{
		printf("using nonblock mode.\n");
	}
	
	if (ctlfile == NULL)
	{
		handle = gpio_open(0);
	}
	else
	{
		handle = gpio_open_device(ctlfile);
	}
	
	if (handle == GPIO_INVALID_HANDLE)
	{
		perror("gpio_open");
		exit(1);
	}
	
	for (i = 0; i < MAXIRQS; i++)
	{
		fds[i].fd = -1;
	}
	
	signal(SIGINT, sig_die);
	signal(SIGHUP, sig_die);
	signal(SIGTERM, sig_die);
	
	for (i = 0; i < nirqs; i++)
	{
		if (gpio_irq_register(handle, irq[i], &unit) < 0)
		{
			perror("gpio_irq_register");
			goto out;
		}
		
		/* Open irq event device. */
		fds[i].fd = gpio_irq_open(unit, flags);
		
		if (fds[i].fd == GPIO_INVALID_HANDLE)
		{
			perror("gpio_irq_open");
			goto out;
		}
		
		fds[i].events = POLLIN;
	}
	
	fprintf(stderr, "READY\n");
	
	if (flags & O_NONBLOCK)
	{
		poll_irq_ev(fds, nirqs);
	}
	else
	{
		read_irq_ev(fds[0].fd);
	}
	
	out:
	
	for (i = 0; i < nirqs; i++)
	{
		if (fds[i].fd != -1)
		{
			gpio_close(fds[i].fd);
		}
		
		if (gpio_irq_unregister(handle, irq[i]) < 0)
		{
			perror("gpio_irq_unregister");
		}
	}
	
	gpio_close(handle);
	
	exit(0);
}