TS-4800 Watchdog

The watchdog is manipulated via the ts4800ctl utility. The default INITRD linuxrc autofeeds the watchdog by daemonizing and feeding it in the background via userspace. It can be armed in 3 modes (0 - .4s, 1- 2.7s, 2 - 10.8s). It can be either auto-fed from a background process that continually feeds the watchdog while running (--autofeed option), or via a /dev/watchdog UNIX named pipe which receives single ASCII characters which are written to feed it from another application.

Value	Result
0	feed watchdog for another .338s
1	feed watchdog for another 2.706s
2	feed watchdog for another 10.824s
3	disable watchdog

Watchdog by default comes out of reset armed for .338 seconds. TS-BOOTROM firmware feeds for 10.824 and OS code has 10.824 seconds to take over.

You can feed this from your own application by touching the feed register:

#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <sys/mman.h>

int main()
{
        int mem;
        volatile uint16_t *syscon;

        mem = open("/dev/mem", O_RDWR|O_SYNC);
        syscon = mmap(0,
                      getpagesize(),
                      PROT_READ|PROT_WRITE,
                      MAP_SHARED,
                      mem,
                      0xb0010000);

        for(;;) {
                // This feeds the watchdog for 10s.
                syscon[0xe/2] = 2;
		sleep(5);
        }

        return 0;
}