Loongson 7A Watchdog Timer Userspace Daemon

wdtd.c

#define _GNU_SOURCE
#include <fcntl.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/sysinfo.h>

static volatile unsigned int *wdtr;

static void
signal_handler (int signum)
{
    wdtr[12] = 0;
    exit (0);
}

int
main (int argc, char *argv[])
{
    int fd, max_cpu;
    void *ptr;

    fd = open ("/dev/mem", O_RDWR | O_DSYNC);
    if (fd < 0) {
        fprintf (stderr, "Open /dev/mem failed!\n");
        goto exit;
    }

    ptr = mmap (NULL, 16384, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
                0x100d0000UL);
    if (ptr == MAP_FAILED) {
        fprintf (stderr, "Map /dev/mem failed!\n");
        goto exit_close;
    }

    wdtr = ptr;
    max_cpu = get_nprocs_conf ();

    signal (SIGINT, signal_handler);
    signal (SIGQUIT, signal_handler);
    signal (SIGTERM, signal_handler);

    wdtr[12] = 2;
    for (;;) {
        int i;
        cpu_set_t set;

        for (i = 0; i < max_cpu; i++) {
            CPU_ZERO (&set);
            CPU_SET (i, &set);

            for (;;) {
                sched_setaffinity (0, sizeof (set), &set);
                if (sched_getcpu () == i) {
                    break;
                }
                sleep (1);
            }
        }

        wdtr[13] = 1;
        sleep (30);
    }

    munmap (ptr, 16384);
exit_close:
    close (fd);
exit:
    return 0;
}