1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * uledmon.c |
4 | * |
5 | * This program creates a new userspace LED class device and monitors it. A |
6 | * timestamp and brightness value is printed each time the brightness changes. |
7 | * |
8 | * Usage: uledmon <device-name> |
9 | * |
10 | * <device-name> is the name of the LED class device to be created. Pressing |
11 | * CTRL+C will exit. |
12 | */ |
13 | |
14 | #include <fcntl.h> |
15 | #include <stdio.h> |
16 | #include <string.h> |
17 | #include <time.h> |
18 | #include <unistd.h> |
19 | |
20 | #include <linux/uleds.h> |
21 | |
22 | int main(int argc, char const *argv[]) |
23 | { |
24 | struct uleds_user_dev uleds_dev; |
25 | int fd, ret; |
26 | int brightness; |
27 | struct timespec ts; |
28 | |
29 | if (argc != 2) { |
30 | fprintf(stderr, "Requires <device-name> argument\n" ); |
31 | return 1; |
32 | } |
33 | |
34 | strncpy(uleds_dev.name, argv[1], LED_MAX_NAME_SIZE); |
35 | uleds_dev.max_brightness = 100; |
36 | |
37 | fd = open("/dev/uleds" , O_RDWR); |
38 | if (fd == -1) { |
39 | perror("Failed to open /dev/uleds" ); |
40 | return 1; |
41 | } |
42 | |
43 | ret = write(fd, &uleds_dev, sizeof(uleds_dev)); |
44 | if (ret == -1) { |
45 | perror("Failed to write to /dev/uleds" ); |
46 | close(fd); |
47 | return 1; |
48 | } |
49 | |
50 | while (1) { |
51 | ret = read(fd, &brightness, sizeof(brightness)); |
52 | if (ret == -1) { |
53 | perror("Failed to read from /dev/uleds" ); |
54 | close(fd); |
55 | return 1; |
56 | } |
57 | clock_gettime(CLOCK_MONOTONIC, &ts); |
58 | printf("[%ld.%09ld] %u\n" , ts.tv_sec, ts.tv_nsec, brightness); |
59 | } |
60 | |
61 | close(fd); |
62 | |
63 | return 0; |
64 | } |
65 | |