From OpenTom

Excerpt from the 2.4.x sourcecode how to use the watchdog:

Create the proper device 'mknod /dev/watchdog c 246 0'
Set watchdog timeout with ioctl on /dev/watchdog (IOW_WD_SET_TIME, in  seconds)
Kick the watchdog within the set time using IOW_WD_KICK (NULL argument)

Source is in the kernel 2.4 trunk ..../drivers/Barcelona/Watchdog/

Note that in the 2.6.x kernel there is no port of the Barcelona Watchdog driver, since it already provides a generic s3c2410 watchdog driver. Of course the userspace is not compatible, since the TTGO driver authors apparently didn't know the generic watchdog api.

Sample Code

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <errno.h>
#include <string.h>

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

    if((fd = open("/dev/watchdog", O_RDWR | O_NOCTTY)) < 0) {
        fprintf(stderr, "could not open watchdog: %s", strerror(errno));
        return 1;
    }

    if(daemonize() < 0) {
        fprintf(stderr, "could not daemonize: %s", strerror(errno));
        return 1;
    }

    while(1) {
        write(fd, "\0", 1);
        sleep(15);
    }
}