// SPDX-License-Identifier: GPL-2.0

#define _GNU_SOURCE

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>
#include <signal.h>

#define POWER_FLOOR_ENABLE_ATTRIBUTE "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_enable"
#define POWER_FLOOR_STATUS_ATTRIBUTE  "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_status"

void power_floor_exit(int signum)
{
        int fd;

        /* Disable feature via sysfs knob */

        fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
        if (fd < 0) {
                perror("Unable to open power floor enable file\n");
                exit(1);
        }

        if (write(fd, "0\n", 2) < 0) {
                perror("Can' disable power floor notifications\n");
                exit(1);
        }

        printf("Disabled power floor notifications\n");

        close(fd);
}

int main(int argc, char **argv)
{
        struct pollfd ufd;
        char status_str[3];
        int fd, ret;

        if (signal(SIGINT, power_floor_exit) == SIG_IGN)
                signal(SIGINT, SIG_IGN);
        if (signal(SIGHUP, power_floor_exit) == SIG_IGN)
                signal(SIGHUP, SIG_IGN);
        if (signal(SIGTERM, power_floor_exit) == SIG_IGN)
                signal(SIGTERM, SIG_IGN);

        /* Enable feature via sysfs knob */
        fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
        if (fd < 0) {
                perror("Unable to open power floor enable file\n");
                exit(1);
        }

        if (write(fd, "1\n", 2) < 0) {
                perror("Can't enable power floor notifications\n");
                exit(1);
        }

        close(fd);

        printf("Enabled power floor notifications\n");

        while (1) {
                fd = open(POWER_FLOOR_STATUS_ATTRIBUTE, O_RDONLY);
                if (fd < 0) {
                        perror("Unable to power floor status file\n");
                        exit(1);
                }

                if ((lseek(fd, 0L, SEEK_SET)) < 0) {
                        fprintf(stderr, "Failed to set pointer to beginning\n");
                        exit(1);
                }

                if (read(fd, status_str, sizeof(status_str)) < 0) {
                        fprintf(stderr, "Failed to read from:%s\n",
                        POWER_FLOOR_STATUS_ATTRIBUTE);
                        exit(1);
                }

                ufd.fd = fd;
                ufd.events = POLLPRI;

                ret = poll(&ufd, 1, -1);
                if (ret < 0) {
                        perror("poll error");
                        exit(1);
                } else if (ret == 0) {
                        printf("Poll Timeout\n");
                } else {
                        if ((lseek(fd, 0L, SEEK_SET)) < 0) {
                                fprintf(stderr, "Failed to set pointer to beginning\n");
                                exit(1);
                        }

                        if (read(fd, status_str, sizeof(status_str)) < 0)
                                exit(0);

                        printf("power floor status: %s\n", status_str);
                }

                close(fd);
        }
}