UCOM_LS_DTR
mask |= UCOM_LS_DTR;
if (notch_bits & UCOM_LS_DTR)
(prev_value & UCOM_LS_DTR) ? 1 : 0);
if (any_bits & UCOM_LS_DTR)
(last_value & UCOM_LS_DTR) ? 1 : 0);
ucom_line_state(sc, UCOM_LS_DTR, 0);
ucom_line_state(sc, 0, UCOM_LS_DTR);