ppbus_request_bus
if ((error = ppbus_request_bus(ppbus, dev, 0, 0)))
error = ppbus_request_bus(device_parent(dev), dev, how, (hz));
int ppbus_request_bus(device_t, device_t, int, unsigned int);
return ppbus_request_bus(sc->sc_dev, dev, PPBUS_WAIT|PPBUS_INTR, (hz));
if (ppbus_request_bus(sc->ppbus, sc->pps_dev.sc_dev,