triviOS/pin_control/pin_control.c

#include <stdio.h>
#include <gpiod.h>

#define GPIO_CHIP "gpiochip0"

struct gpiod_chip *chip;

int init_gpio() {
    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_open_by_name.html
    chip = gpiod_chip_open_by_name(GPIO_CHIP);
    if (!chip) {
        printf("Error opening GPIO chip");
        return -1;
    }
    return 0;
}

void cleanup_gpio() {
    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_close.html
    gpiod_chip_close(chip);
}

int set_pin_state(int pin, int state) {
    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_get_line.html
    struct gpiod_line *line = gpiod_chip_get_line(chip, pin);   // this may need an offset
    if (!line) {
        printf("Error getting GPIO line");
        return -1;
    }

    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_request_output.html
    if (gpiod_line_request_output(line, "house-leds", state) < 0) {
        printf("Error setting GPIO line direction");
        gpiod_line_release(line);
        return -1;
    }

    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_set_value.html
    if (gpiod_line_set_value(line, state) < 0) {
        printf("Error setting GPIO line value");
        gpiod_line_release(line);
        return -1;
    }

    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_release.html
    gpiod_line_release(line);
    return 0;
}

int read_button(int pin) {
    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_get_line.html
    struct gpiod_line *line = gpiod_chip_get_line(chip, pin + PIN_OFFSET);
    if (!line) {
        printf("Error getting GPIO line");
        return -1;
    }

    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_request_input.html
    if (gpiod_line_request_input(line, "house-leds") < 0) {
        printf("Error setting GPIO line direction to input");
        gpiod_line_release(line);
        return -1;
    }

    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_get_value.html
    int value = gpiod_line_get_value(line);
    gpiod_line_release(line);
    return value; // either 0 or 1
}

int turn_on_pin(int pin) {
    return set_pin_state(pin, 1);
}

int turn_off_pin(int pin) {
    return set_pin_state(pin, 0);
}

int turn_on_all_pins() {
    for (int pin = 0; pin <= 5; pin++) {
        if (turn_on_pin(pin) < 0)
            return -1;
    }
    return 0;
}

int turn_off_all_pins() {
    for (int pin = 0; pin <= 5; pin++) {
        if (turn_off_pin(pin) < 0)
            return -1;
    }
    return 0;
}

int wait_for_button_press(int button_pin) {
    while (1) {
        int button_state = read_button(button_pin); // maybe make it so that this works with a range of pins instead of just one
        if (button_state == 1) {
            return button_pin;
        }
    }
}