The function of the generic watchdog is to count for a fixed period of time, during which it expects to be refreshed by system software indicating normal operation. If a refresh occurs within the watch period, the counter is refreshed. If the software refresh does not occur, then the watch period expires, a signal is raised, and a second watch period starts.
The initial signal is typically wired to an interrupt and alerts the system software. The system software can attempt to take corrective action that includes refreshing the watchdog within the second watch period. If the refresh is successful, the system returns to the previous normal operation. If it fails, the second watch period expires, and a second signal is generated. The signal is fed to a higher agent as an interrupt or reset for it to take executive action.
The watchdog uses the generic timer counter as the timebase for determining when to trigger an interrupt.