power_floor_test.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#define _GNU_SOURCE
  4
  5#include <stdio.h>
  6#include <string.h>
  7#include <stdlib.h>
  8#include <unistd.h>
  9#include <fcntl.h>
 10#include <poll.h>
 11#include <signal.h>
 12
 13#define POWER_FLOOR_ENABLE_ATTRIBUTE "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_enable"
 14#define POWER_FLOOR_STATUS_ATTRIBUTE  "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_status"
 15
 16void power_floor_exit(int signum)
 17{
 18	int fd;
 19
 20	/* Disable feature via sysfs knob */
 21
 22	fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
 23	if (fd < 0) {
 24		perror("Unable to open power floor enable file\n");
 25		exit(1);
 26	}
 27
 28	if (write(fd, "0\n", 2) < 0) {
 29		perror("Can' disable power floor notifications\n");
 30		exit(1);
 31	}
 32
 33	printf("Disabled power floor notifications\n");
 34
 35	close(fd);
 36}
 37
 38int main(int argc, char **argv)
 39{
 40	struct pollfd ufd;
 41	char status_str[3];
 42	int fd, ret;
 43
 44	if (signal(SIGINT, power_floor_exit) == SIG_IGN)
 45		signal(SIGINT, SIG_IGN);
 46	if (signal(SIGHUP, power_floor_exit) == SIG_IGN)
 47		signal(SIGHUP, SIG_IGN);
 48	if (signal(SIGTERM, power_floor_exit) == SIG_IGN)
 49		signal(SIGTERM, SIG_IGN);
 50
 51	/* Enable feature via sysfs knob */
 52	fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
 53	if (fd < 0) {
 54		perror("Unable to open power floor enable file\n");
 55		exit(1);
 56	}
 57
 58	if (write(fd, "1\n", 2) < 0) {
 59		perror("Can't enable power floor notifications\n");
 60		exit(1);
 61	}
 62
 63	close(fd);
 64
 65	printf("Enabled power floor notifications\n");
 66
 67	while (1) {
 68		fd = open(POWER_FLOOR_STATUS_ATTRIBUTE, O_RDONLY);
 69		if (fd < 0) {
 70			perror("Unable to power floor status file\n");
 71			exit(1);
 72		}
 73
 74		if ((lseek(fd, 0L, SEEK_SET)) < 0) {
 75			fprintf(stderr, "Failed to set pointer to beginning\n");
 76			exit(1);
 77		}
 78
 79		if (read(fd, status_str, sizeof(status_str)) < 0) {
 80			fprintf(stderr, "Failed to read from:%s\n",
 81			POWER_FLOOR_STATUS_ATTRIBUTE);
 82			exit(1);
 83		}
 84
 85		ufd.fd = fd;
 86		ufd.events = POLLPRI;
 87
 88		ret = poll(&ufd, 1, -1);
 89		if (ret < 0) {
 90			perror("poll error");
 91			exit(1);
 92		} else if (ret == 0) {
 93			printf("Poll Timeout\n");
 94		} else {
 95			if ((lseek(fd, 0L, SEEK_SET)) < 0) {
 96				fprintf(stderr, "Failed to set pointer to beginning\n");
 97				exit(1);
 98			}
 99
100			if (read(fd, status_str, sizeof(status_str)) < 0)
101				exit(0);
102
103			printf("power floor status: %s\n", status_str);
104		}
105
106		close(fd);
107	}
108}