REG_BEEP_CONTROL
bctrl = ykbec_read(sc, REG_BEEP_CONTROL);
ykbec_write(sc, REG_BEEP_CONTROL, bctrl & ~BEEP_ENABLE);
ykbec_write(sc, REG_BEEP_CONTROL, bctrl | BEEP_ENABLE);
ykbec_write(sc, REG_BEEP_CONTROL, bctrl & ~BEEP_ENABLE);
ykbec_write(sc, REG_BEEP_CONTROL,
ykbec_read(sc, REG_BEEP_CONTROL) & ~BEEP_ENABLE);