1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
2ae347323SJacek Anaszewski /*
3ae347323SJacek Anaszewski * led_hw_brightness_mon.c
4ae347323SJacek Anaszewski *
5ae347323SJacek Anaszewski * This program monitors LED brightness level changes having its origin
6ae347323SJacek Anaszewski * in hardware/firmware, i.e. outside of kernel control.
7ae347323SJacek Anaszewski * A timestamp and brightness value is printed each time the brightness changes.
8ae347323SJacek Anaszewski *
9ae347323SJacek Anaszewski * Usage: led_hw_brightness_mon <device-name>
10ae347323SJacek Anaszewski *
11ae347323SJacek Anaszewski * <device-name> is the name of the LED class device to be monitored. Pressing
12ae347323SJacek Anaszewski * CTRL+C will exit.
13ae347323SJacek Anaszewski */
14ae347323SJacek Anaszewski
15ae347323SJacek Anaszewski #include <errno.h>
16ae347323SJacek Anaszewski #include <fcntl.h>
17ae347323SJacek Anaszewski #include <poll.h>
18ae347323SJacek Anaszewski #include <stdio.h>
19ae347323SJacek Anaszewski #include <stdlib.h>
20ae347323SJacek Anaszewski #include <string.h>
21ae347323SJacek Anaszewski #include <time.h>
22ae347323SJacek Anaszewski #include <unistd.h>
23ae347323SJacek Anaszewski
24ae347323SJacek Anaszewski #include <linux/uleds.h>
25ae347323SJacek Anaszewski
main(int argc,char const * argv[])26ae347323SJacek Anaszewski int main(int argc, char const *argv[])
27ae347323SJacek Anaszewski {
28ae347323SJacek Anaszewski int fd, ret;
29ae347323SJacek Anaszewski char brightness_file_path[LED_MAX_NAME_SIZE + 11];
30ae347323SJacek Anaszewski struct pollfd pollfd;
31ae347323SJacek Anaszewski struct timespec ts;
32ae347323SJacek Anaszewski char buf[11];
33ae347323SJacek Anaszewski
34ae347323SJacek Anaszewski if (argc != 2) {
35ae347323SJacek Anaszewski fprintf(stderr, "Requires <device-name> argument\n");
36ae347323SJacek Anaszewski return 1;
37ae347323SJacek Anaszewski }
38ae347323SJacek Anaszewski
39ae347323SJacek Anaszewski snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
40ae347323SJacek Anaszewski "/sys/class/leds/%s/brightness_hw_changed", argv[1]);
41ae347323SJacek Anaszewski
42ae347323SJacek Anaszewski fd = open(brightness_file_path, O_RDONLY);
43ae347323SJacek Anaszewski if (fd == -1) {
44ae347323SJacek Anaszewski printf("Failed to open %s file\n", brightness_file_path);
45ae347323SJacek Anaszewski return 1;
46ae347323SJacek Anaszewski }
47ae347323SJacek Anaszewski
48ae347323SJacek Anaszewski /*
49ae347323SJacek Anaszewski * read may fail if no hw brightness change has occurred so far,
50ae347323SJacek Anaszewski * but it is required to avoid spurious poll notifications in
51ae347323SJacek Anaszewski * the opposite case.
52ae347323SJacek Anaszewski */
53ae347323SJacek Anaszewski read(fd, buf, sizeof(buf));
54ae347323SJacek Anaszewski
55ae347323SJacek Anaszewski pollfd.fd = fd;
56ae347323SJacek Anaszewski pollfd.events = POLLPRI;
57ae347323SJacek Anaszewski
58ae347323SJacek Anaszewski while (1) {
59ae347323SJacek Anaszewski ret = poll(&pollfd, 1, -1);
60ae347323SJacek Anaszewski if (ret == -1) {
61ae347323SJacek Anaszewski printf("Failed to poll %s file (%d)\n",
62ae347323SJacek Anaszewski brightness_file_path, ret);
63ae347323SJacek Anaszewski ret = 1;
64ae347323SJacek Anaszewski break;
65ae347323SJacek Anaszewski }
66ae347323SJacek Anaszewski
67ae347323SJacek Anaszewski clock_gettime(CLOCK_MONOTONIC, &ts);
68ae347323SJacek Anaszewski
69ae347323SJacek Anaszewski ret = read(fd, buf, sizeof(buf));
70ae347323SJacek Anaszewski if (ret < 0)
71ae347323SJacek Anaszewski break;
72ae347323SJacek Anaszewski
73ae347323SJacek Anaszewski ret = lseek(pollfd.fd, 0, SEEK_SET);
74ae347323SJacek Anaszewski if (ret < 0) {
75ae347323SJacek Anaszewski printf("lseek failed (%d)\n", ret);
76ae347323SJacek Anaszewski break;
77ae347323SJacek Anaszewski }
78ae347323SJacek Anaszewski
79ae347323SJacek Anaszewski printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
80ae347323SJacek Anaszewski }
81ae347323SJacek Anaszewski
82ae347323SJacek Anaszewski close(fd);
83ae347323SJacek Anaszewski
84ae347323SJacek Anaszewski return ret;
85ae347323SJacek Anaszewski }
86