pcppi_bell_stop
timeout_set(&sc->sc_bell_timeout, pcppi_bell_stop, sc);
wakeup(pcppi_bell_stop);
pcppi_bell_stop(sc);
pcppi_bell_stop(sc);
tsleep_nsec(pcppi_bell_stop, PCPPIPRI | PCATCH, "bell",
wakeup(pcppi_bell_stop);
static void pcppi_bell_stop(void *);