Commit | Line | Data |
---|---|---|
ae347323 JA |
1 | /* |
2 | * led_hw_brightness_mon.c | |
3 | * | |
4 | * This program monitors LED brightness level changes having its origin | |
5 | * in hardware/firmware, i.e. outside of kernel control. | |
6 | * A timestamp and brightness value is printed each time the brightness changes. | |
7 | * | |
8 | * Usage: led_hw_brightness_mon <device-name> | |
9 | * | |
10 | * <device-name> is the name of the LED class device to be monitored. Pressing | |
11 | * CTRL+C will exit. | |
12 | */ | |
13 | ||
14 | #include <errno.h> | |
15 | #include <fcntl.h> | |
16 | #include <poll.h> | |
17 | #include <stdio.h> | |
18 | #include <stdlib.h> | |
19 | #include <string.h> | |
20 | #include <time.h> | |
21 | #include <unistd.h> | |
22 | ||
23 | #include <linux/uleds.h> | |
24 | ||
25 | int main(int argc, char const *argv[]) | |
26 | { | |
27 | int fd, ret; | |
28 | char brightness_file_path[LED_MAX_NAME_SIZE + 11]; | |
29 | struct pollfd pollfd; | |
30 | struct timespec ts; | |
31 | char buf[11]; | |
32 | ||
33 | if (argc != 2) { | |
34 | fprintf(stderr, "Requires <device-name> argument\n"); | |
35 | return 1; | |
36 | } | |
37 | ||
38 | snprintf(brightness_file_path, LED_MAX_NAME_SIZE, | |
39 | "/sys/class/leds/%s/brightness_hw_changed", argv[1]); | |
40 | ||
41 | fd = open(brightness_file_path, O_RDONLY); | |
42 | if (fd == -1) { | |
43 | printf("Failed to open %s file\n", brightness_file_path); | |
44 | return 1; | |
45 | } | |
46 | ||
47 | /* | |
48 | * read may fail if no hw brightness change has occurred so far, | |
49 | * but it is required to avoid spurious poll notifications in | |
50 | * the opposite case. | |
51 | */ | |
52 | read(fd, buf, sizeof(buf)); | |
53 | ||
54 | pollfd.fd = fd; | |
55 | pollfd.events = POLLPRI; | |
56 | ||
57 | while (1) { | |
58 | ret = poll(&pollfd, 1, -1); | |
59 | if (ret == -1) { | |
60 | printf("Failed to poll %s file (%d)\n", | |
61 | brightness_file_path, ret); | |
62 | ret = 1; | |
63 | break; | |
64 | } | |
65 | ||
66 | clock_gettime(CLOCK_MONOTONIC, &ts); | |
67 | ||
68 | ret = read(fd, buf, sizeof(buf)); | |
69 | if (ret < 0) | |
70 | break; | |
71 | ||
72 | ret = lseek(pollfd.fd, 0, SEEK_SET); | |
73 | if (ret < 0) { | |
74 | printf("lseek failed (%d)\n", ret); | |
75 | break; | |
76 | } | |
77 | ||
78 | printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf)); | |
79 | } | |
80 | ||
81 | close(fd); | |
82 | ||
83 | return ret; | |
84 | } |