86 lines
1.8 KiB
C
86 lines
1.8 KiB
C
|
// SPDX-License-Identifier: GPL-2.0
|
||
|
|
/*
|
||
|
|
* led_hw_brightness_mon.c
|
||
|
|
*
|
||
|
|
* This program monitors LED brightness level changes having its origin
|
||
|
|
* in hardware/firmware, i.e. outside of kernel control.
|
||
|
|
* A timestamp and brightness value is printed each time the brightness changes.
|
||
|
|
*
|
||
|
|
* Usage: led_hw_brightness_mon <device-name>
|
||
|
|
*
|
||
|
|
* <device-name> is the name of the LED class device to be monitored. Pressing
|
||
|
|
* CTRL+C will exit.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <errno.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <poll.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <string.h>
|
||
|
|
#include <time.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
#include <linux/uleds.h>
|
||
|
|
|
||
|
|
int main(int argc, char const *argv[])
|
||
|
|
{
|
||
|
|
int fd, ret;
|
||
|
|
char brightness_file_path[LED_MAX_NAME_SIZE + 11];
|
||
|
|
struct pollfd pollfd;
|
||
|
|
struct timespec ts;
|
||
|
|
char buf[11];
|
||
|
|
|
||
|
|
if (argc != 2) {
|
||
|
|
fprintf(stderr, "Requires <device-name> argument\n");
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
|
||
|
|
"/sys/class/leds/%s/brightness_hw_changed", argv[1]);
|
||
|
|
|
||
|
|
fd = open(brightness_file_path, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
printf("Failed to open %s file\n", brightness_file_path);
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* read may fail if no hw brightness change has occurred so far,
|
||
|
|
* but it is required to avoid spurious poll notifications in
|
||
|
|
* the opposite case.
|
||
|
|
*/
|
||
|
|
read(fd, buf, sizeof(buf));
|
||
|
|
|
||
|
|
pollfd.fd = fd;
|
||
|
|
pollfd.events = POLLPRI;
|
||
|
|
|
||
|
|
while (1) {
|
||
|
|
ret = poll(&pollfd, 1, -1);
|
||
|
|
if (ret == -1) {
|
||
|
|
printf("Failed to poll %s file (%d)\n",
|
||
|
|
brightness_file_path, ret);
|
||
|
|
ret = 1;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
clock_gettime(CLOCK_MONOTONIC, &ts);
|
||
|
|
|
||
|
|
ret = read(fd, buf, sizeof(buf));
|
||
|
|
if (ret < 0)
|
||
|
|
break;
|
||
|
|
|
||
|
|
ret = lseek(pollfd.fd, 0, SEEK_SET);
|
||
|
|
if (ret < 0) {
|
||
|
|
printf("lseek failed (%d)\n", ret);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
|
||
|
|
}
|
||
|
|
|
||
|
|
close(fd);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|