/*
 * gpio.cpp
 *
 *  Created on: Mar 6, 2012
 *      Author: joe
 */
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "gpio.h"

#define GPIO_DIR_IN	    0
#define GPIO_DIR_OUT	1

int gpio_export(unsigned gpio)
{
	int fd, len;
	char buf[11];

	fd = open("/sys/class/gpio/export", O_WRONLY);
	if (fd < 0) {
		perror("gpio/export");
		return fd;
	}

	len = snprintf(buf, sizeof(buf), "%d", gpio);
	write(fd, buf, len);
	close(fd);

	return 0;
}

int gpio_unexport(unsigned gpio)
{
	int fd, len;
	char buf[11];

	fd = open("/sys/class/gpio/unexport", O_WRONLY);
	if (fd < 0) {
		perror("gpio/export");
		return fd;
	}

	len = snprintf(buf, sizeof(buf), "%d", gpio);
	write(fd, buf, len);
	close(fd);
	return 0;
}

static int gpio_dir(unsigned gpio, unsigned dir)
{
	int fd, len;
	char buf[60];

	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);

	fd = open(buf, O_WRONLY);
	if (fd < 0) {
		perror("gpio/direction");
		return fd;
	}

	if (dir == GPIO_DIR_OUT)
		write(fd, "out", 4);
	else
		write(fd, "in", 3);

	close(fd);
	return 0;
}

int gpio_dir_out(unsigned gpio)
{
	return gpio_dir(gpio, GPIO_DIR_OUT);
}

int gpio_dir_in(unsigned gpio)
{
	return gpio_dir(gpio, GPIO_DIR_IN);
}

int gpio_set_value(unsigned gpio, unsigned value)
{
	int fd, len;
	char buf[60];

	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);

	fd = open(buf, O_WRONLY);
	if (fd < 0) {
		perror("gpio/value");
		return fd;
	}

	if (value)
		write(fd, "1", 2);
	else
		write(fd, "0", 2);

	close(fd);
	return 0;
}

int gpio_get_value(unsigned gpio, unsigned *value)
{
	int fd, len;
	char buf[60];

	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);

	fd = open(buf, O_RDONLY);
	if (fd < 0) {
		perror("gpio/value");
		return fd;
	}

	read(fd, value, 1);

	if (*value == '1')
		*value = 1;
	else
		*value = 0;

	close(fd);
	return 0;
}