SimpleGPIO.cpp

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/*
 * SimpleGPIO.cpp
 *
 * Modifications by Derek Molloy, School of Electronic Engineering, DCU
 * www.eeng.dcu.ie/~molloyd/
 * Almost entirely based on Software by RidgeRun:
 *
 * Copyright (c) 2011, RidgeRun
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the RidgeRun.
 * 4. Neither the name of the RidgeRun nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY RIDGERUN ''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 RIDGERUN 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.
 */
 
#include "SimpleGPIO.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>
 
/****************************************************************
 * gpio_export
 ****************************************************************/
int gpio_export(unsigned int gpio)
{
    int fd, len;
    char buf[MAX_BUF];
 
    fd = open(SYSFS_GPIO_DIR "/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;
}
 
/****************************************************************
 * gpio_unexport
 ****************************************************************/
int gpio_unexport(unsigned int gpio)
{
    int fd, len;
    char buf[MAX_BUF];
 
    fd = open(SYSFS_GPIO_DIR "/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;
}
 
/****************************************************************
 * gpio_set_dir
 ****************************************************************/
int gpio_set_dir(unsigned int gpio, PIN_DIRECTION out_flag)
{
    int fd;
    char buf[MAX_BUF];
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR  "/gpio%d/direction", gpio);
 
    fd = open(buf, O_WRONLY);
    if (fd < 0) {
        perror("gpio/direction");
        return fd;
    }
 
    if (out_flag == OUTPUT_PIN)
        write(fd, "out", 4);
    else
        write(fd, "in", 3);
 
    close(fd);
    return 0;
}
 
/****************************************************************
 * gpio_set_value
 ****************************************************************/
int gpio_set_value(unsigned int gpio, PIN_VALUE value)
{
    int fd;
    char buf[MAX_BUF];
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
 
    fd = open(buf, O_WRONLY);
    if (fd < 0) {
        perror("gpio/set-value");
        return fd;
    }
 
    if (value==LOW)
        write(fd, "0", 2);
    else
        write(fd, "1", 2);
 
    close(fd);
    return 0;
}
 
/****************************************************************
 * gpio_get_value
 ****************************************************************/
int gpio_get_value(unsigned int gpio, unsigned int *value)
{
    int fd;
    char buf[MAX_BUF];
    char ch;
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
 
    fd = open(buf, O_RDONLY);
    if (fd < 0) {
        perror("gpio/get-value");
        return fd;
    }
 
    read(fd, &ch, 1);
 
    if (ch != '0') {
        *value = 1;
    } else {
        *value = 0;
    }
 
    close(fd);
    return 0;
}
 
 
/****************************************************************
 * gpio_set_edge
 ****************************************************************/
 
int gpio_set_edge(unsigned int gpio, char *edge)
{
    int fd;
    char buf[MAX_BUF];
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/edge", gpio);
 
    fd = open(buf, O_WRONLY);
    if (fd < 0) {
        perror("gpio/set-edge");
        return fd;
    }
 
    write(fd, edge, strlen(edge) + 1);
    close(fd);
    return 0;
}
 
/****************************************************************
 * gpio_fd_open
 ****************************************************************/
 
int gpio_fd_open(unsigned int gpio)
{
    int fd;
    char buf[MAX_BUF];
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
 
    fd = open(buf, O_RDONLY | O_NONBLOCK );
    if (fd < 0) {
        perror("gpio/fd_open");
    }
    return fd;
}
 
/****************************************************************
 * gpio_fd_close
 ****************************************************************/
 
int gpio_fd_close(int fd)
{
    return close(fd);
}
 
 
/****************************************************************
 * gpio_omap_mux_setup - Allow us to setup the omap mux mode for a pin
 ****************************************************************/
int gpio_omap_mux_setup(const char *omap_pin0_name, const char *mode)
{
    int fd;
    char buf[MAX_BUF];
    snprintf(buf, sizeof(buf), SYSFS_OMAP_MUX_DIR "%s", omap_pin0_name);
    fd = open(buf, O_WRONLY);
    if (fd < 0) {
        perror("failed to open OMAP_MUX");
        return fd;
    }
    write(fd, mode, strlen(mode) + 1);
    close(fd);
    return 0;
}