IER_ERLS
if (ISSET(sc->sc_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC))
if (ISSET(sc->sc_imr, IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC))
sc->sc_ier = IER_ERLS; /* interrupt on line break */
sc->sc_ier = IER_ERXRDY | IER_ERLS;
if (ISSET(sc->sc_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC))
sc->sc_ier = IER_ERLS;