CLOCK_SOURCE_WATCHDOG
cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) ||
cs->flags |= CLOCK_SOURCE_WATCHDOG;
cs->flags &= ~CLOCK_SOURCE_WATCHDOG;