BBB-Simple-ACS/client/lib/gpio.cpp

/*
 * GPIO.cpp  Created on: 29 Apr 2014
 * Copyright (c) 2014 Derek Molloy (www.derekmolloy.ie)
 * Made available for the book "Exploring BeagleBone"
 * If you use this code in your work please cite:
 *   Derek Molloy, "Exploring BeagleBone: Tools and Techniques for Building
 *   with Embedded Linux", Wiley, 2014, ISBN:9781118935125.
 * See: www.exploringbeaglebone.com
 * Licensed under the EUPL V.1.1
 *
 * This Software is provided to You under the terms of the European
 * Union Public License (the "EUPL") version 1.1 as published by the
 * European Union. Any use of this Software, other than as authorized
 * under this License is strictly prohibited (to the extent such use
 * is covered by a right of the copyright holder of this Software).
 *
 * This Software is provided under the License on an "AS IS" basis and
 * without warranties of any kind concerning the Software, including
 * without limitation merchantability, fitness for a particular purpose,
 * absence of defects or errors, accuracy, and non-infringement of
 * intellectual property rights other than copyright. This disclaimer
 * of warranty is an essential part of the License and a condition for
 * the grant of any rights to this Software.
 *
 * For more details, see http://www.derekmolloy.ie/
 */

#include "gpio.hpp"
#include <fstream>
#include <string>
#include <iostream>
#include <unistd.h>

int gpio::write(const std::string& path, const std::string& filename, const std::string& value) {
    std::ofstream fs;
    fs.open(path + filename);
    if (!fs.is_open()) {
        std::cerr << "GPIO: write failed to open file." << std::endl;
        return -1;
    }
    fs << value;
    fs.close();
    return 0;
}

std::string gpio::read(const std::string& path, const std::string& filename) {
    std::ifstream fs;
    fs.open(path + filename);
    if (!fs.is_open()) {
        std::cerr << "GPIO: read failed to open file " << std::endl;
        return { };
    }
    std::string input;
    getline(fs, input);
    fs.close();
    return input;
}

int gpio::write(const std::string& path, const std::string& filename, int value) {
    return write(path, filename, std::to_string(value));
}

gpio::gpio(int number) : number_(number)
{
    name_ = std::string("gpio") + std::to_string(number);
    path_ = std::string(base_path) + this->name_ + "/";
    this->export_gpio();
    // Need to give Linux time to set up the sysfs structure
    usleep(300'000);
}

int gpio::export_gpio()
{
    return write(base_path, "export", number_);
}

int gpio::unexport_gpio()
{
    return write(base_path, "unexport", number_);
}

int gpio::set_direction(direction dir)
{
    switch (dir) {
    case input:
        return write(path_, "direction", "in");
    case output:
        return write(path_, "direction", "out");
    }
    return -1;
}

int gpio::set_value(value value)
{
    switch (value) {
    case high:
        return write(path_, "value", "1");
    case low:
        return write(path_, "value", "0");
    }
    return -1;
}

int gpio::set_edge_type(edge value)
{
    switch (value) {
    case none:
        return write(path_, "edge", "none");
    case rising:
        return write(path_, "edge", "rising");
    case falling:
        return write(path_, "edge", "falling");
    case both:
        return write(path_, "edge", "both");
    }
    return -1;
}

int gpio::set_active_low(bool is_low)
{
    if (is_low)
        return write(path_, "active_low", "1");
    return write(path_, "active_low", "0");
}

int gpio::set_active_high()
{
    return this->set_active_low(false);
}

gpio::value gpio::get_value() const
{
    auto input = read(path_, "value");
    if (input == "0")
        return low;
    return high;
}

gpio::direction gpio::get_direction() const
{
    auto direction = read(path_, "direction");
    if (direction == "in")
        return input;
    return output;
}

gpio::edge gpio::get_edge_type() const
{
    auto edge = read(path_, "edge");
    if (edge == "rising")
        return rising;
    if (edge == "falling")
        return falling;
    if (edge == "both")
        return both;
    return none;
}

int gpio::stream_open()
{
    stream_.open(path_ + "value");
    return 0;
}
int gpio::stream_write(value value)
{
    stream_ << value << std::flush;
    return 0;
}
int gpio::stream_close()
{
    stream_.close();
    return 0;
}

int gpio::toggle_output()
{
    set_direction(output);
    if (get_value())
        set_value(low);
    else
        set_value(high);
    return 0;
}

gpio::~gpio() {
    this->unexport_gpio();
}