// SPDX-License-Identifier: GPL-2.0
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/*
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* uledmon.c
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*
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* This program creates a new userspace LED class device and monitors it. A
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* timestamp and brightness value is printed each time the brightness changes.
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*
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* Usage: uledmon <device-name>
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*
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* <device-name> is the name of the LED class device to be created. Pressing
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* CTRL+C will exit.
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*/
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <linux/uleds.h>
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int main(int argc, char const *argv[])
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{
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struct uleds_user_dev uleds_dev;
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int fd, ret;
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int brightness;
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struct timespec ts;
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if (argc != 2) {
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fprintf(stderr, "Requires <device-name> argument\n");
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return 1;
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}
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strncpy(uleds_dev.name, argv[1], LED_MAX_NAME_SIZE);
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uleds_dev.max_brightness = 100;
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fd = open("/dev/uleds", O_RDWR);
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if (fd == -1) {
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perror("Failed to open /dev/uleds");
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return 1;
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}
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ret = write(fd, &uleds_dev, sizeof(uleds_dev));
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if (ret == -1) {
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perror("Failed to write to /dev/uleds");
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close(fd);
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return 1;
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}
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while (1) {
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ret = read(fd, &brightness, sizeof(brightness));
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if (ret == -1) {
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perror("Failed to read from /dev/uleds");
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close(fd);
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return 1;
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}
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clock_gettime(CLOCK_MONOTONIC, &ts);
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printf("[%ld.%09ld] %u\n", ts.tv_sec, ts.tv_nsec, brightness);
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}
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close(fd);
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return 0;
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}
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