gpio sysfs 操作接口

老外写的，直接哪里用

/*
 * SimpleGPIO.cpp
 *
 * Modifications by Derek Molloy, School of Electronic Engineering, DCU
 * www.derekmolloy.ie
 * 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);
}

/*
 * SimpleGPIO.h
 *
 * Copyright Derek Molloy, School of Electronic Engineering, Dublin City University
 * www.derekmolloy.ie
 *
 * 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.
 */

#ifndef SIMPLEGPIO_H_
#define SIMPLEGPIO_H_

 /****************************************************************
 * Constants
 ****************************************************************/

#define SYSFS_GPIO_DIR "/sys/class/gpio"
#define POLL_TIMEOUT (3 * 1000) /* 3 seconds */
#define MAX_BUF 64

enum PIN_DIRECTION{
    INPUT_PIN=0,
    OUTPUT_PIN=1
};

enum PIN_VALUE{
    LOW=0,
    HIGH=1
};

/****************************************************************
 * gpio_export
 ****************************************************************/
int gpio_export(unsigned int gpio);
int gpio_unexport(unsigned int gpio);
int gpio_set_dir(unsigned int gpio, PIN_DIRECTION out_flag);
int gpio_set_value(unsigned int gpio, PIN_VALUE value);
int gpio_get_value(unsigned int gpio, unsigned int *value);
int gpio_set_edge(unsigned int gpio, char *edge);
int gpio_fd_open(unsigned int gpio);
int gpio_fd_close(int fd);

#endif /* SIMPLEGPIO_H_ */

/*
 * TestApplication.cpp
 *
 * Copyright Derek Molloy, School of Electronic Engineering, Dublin City University
 * www.derekmolloy.ie
 *
 * YouTube Channel: http://www.youtube.com/derekmolloydcu/
 *
 * 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 ''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 I
 * 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 <iostream>
#include <string>
#include <unistd.h>
#include "SimpleGPIO.h"
using namespace std;

unsigned int LEDGPIO = 60; // GPIO1_28 = (1x32) + 28 = 60
unsigned int ButtonGPIO = 15; // GPIO0_15 = (0x32) + 15 = 15

int main(int argc, char *argv[]){

    cout << "Testing the GPIO Pins" << endl;

        gpio_export(LEDGPIO); // The LED
    gpio_export(ButtonGPIO); // The push button switch
        gpio_set_dir(LEDGPIO, OUTPUT_PIN); // The LED is an output
    gpio_set_dir(ButtonGPIO, INPUT_PIN); // The push button input

    // Flash the LED 5 times
    for(int i=0; i<5; i++){
        cout << "Setting the LED on" << endl;
                gpio_set_value(LEDGPIO, HIGH);
        usleep(200000); // on for 200ms
        cout << "Setting the LED off" << endl;
                gpio_set_value(LEDGPIO, LOW);
        usleep(200000); // off for 200ms
    }

    // Wait for the push button to be pressed
    cout << "Please press the button!" << endl;

    unsigned int value = LOW;
    do {
        gpio_get_value(ButtonGPIO, &value);
        cout << ".";
        usleep(1000); // sleep for one millisecond
    } while (value!=HIGH);
    cout << endl << "Button was just pressed!" << endl;

    cout << "Finished Testing the GPIO Pins" << endl;
    gpio_unexport(LEDGPIO); // unexport the LED
    gpio_unexport(ButtonGPIO); // unexport the push button
    return 0;
}