TS-4710 Watchdog

The watchdog is manipulated via the tshwctl utility. The startup scripts automatically run and daemonize tshwctl to feed the watchdog by default. 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 the watchdog from your application by poking a register:

#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <assert.h>

static volatile unsigned short *syscon;
static unsigned short peek16(unsigned int adr) {
	return syscon[adr / 2];
}

static void poke16(unsigned int adr, unsigned short val) {
	syscon[adr / 2] = val;
}
 
int main(void) {
     int devmem = open("/dev/mem", O_RDWR|O_SYNC);
 
     assert(devmem != -1);
     syscon = (unsigned short *) mmap(0, 4096,
          PROT_READ | PROT_WRITE, MAP_SHARED, devmem, 0x80004000);
 
     while(1) {
          poke16(0x6, 0x2); // Feed watchdog
          sleep(5);
     }
 
     return 0;
}