UMSR_CTS
com->c_msr = UMSR_DSR | UMSR_CTS | UMSR_DCD;
if (ISSET(combits, UMSR_CTS))
sc->sc_msr |= UMSR_CTS;
*msr = ISSET(mdmsts, SLSA_MDMSTS_CTS) ? UMSR_CTS : 0;
SET(sc->sc_msr, UMSR_CTS);