zircon/system/uapp/backlight/main.c

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <fcntl.h>
#include <fuchsia/hardware/backlight/c/fidl.h>
#include <lib/fdio/unsafe.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void usage(char* argv[]) {
    printf("Usage: %s [--read|--off|<brightness-val>]\n", argv[0]);
    printf("options:\n    <brightness-val>: 0-255\n");
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        usage(argv);
        return -1;
    }

    int fd = open("/dev/class/backlight/000", O_RDONLY);
    if (fd < 0) {
        printf("Failed to open backlight\n");
        return -1;
    }

    fdio_t* io = fdio_unsafe_fd_to_io(fd);
    if (io == NULL) {
        printf("Failed to get fdio_t\n");
        return -1;
    }
    zx_handle_t channel = fdio_unsafe_borrow_channel(io);

    if (strcmp(argv[1], "--read") == 0) {
        fuchsia_hardware_backlight_State state;
        zx_status_t status = fuchsia_hardware_backlight_DeviceGetState(channel, &state);
        if (status != ZX_OK) {
            printf("Get backlight state failed %d\n", status);
            return -1;
        }
        printf("Backlight:%s Brightness:%d\n", state.on ? "on" : "off", state.brightness);
        return 0;
    }

    bool on;
    uint32_t brightness;
    if (strcmp(argv[1], "--off") == 0) {
        on = false;
        brightness = 0;
    } else {
        char* endptr;
        brightness = strtoul(argv[1], &endptr, 10);
        if (endptr == argv[1] || *endptr != '\0') {
            usage(argv);
            return -1;
        }
        if (brightness > 255) {
            printf("Invalid brightness %d\n", brightness);
            return -1;
        }
        on = true;
    }

    fuchsia_hardware_backlight_State state = {.on = on, .brightness = (uint8_t)brightness};
    zx_status_t status = fuchsia_hardware_backlight_DeviceSetState(channel, &state);
    if (status != ZX_OK) {
        printf("Set brightness failed %d\n", status);
        return -1;
    }

    return 0;
}