twa_watchdog
static TW_VOID twa_watchdog(TW_VOID *arg);
callout_reset(&(sc->watchdog_callout[0]), 5*hz, twa_watchdog, &sc->ctlr_handle);
callout_reset(&(sc->watchdog_callout[i]), 70*hz, twa_watchdog, &sc->ctlr_handle);
callout_reset(&(sc->watchdog_callout[i]), 5*hz, twa_watchdog, &sc->ctlr_handle);