wsmux_getmux
mux = wsmux_getmux(kbdmux);
wsmux_sc = wsmux_getmux(mux);
error = wsmux_attach_sc(wsmux_getmux(mux), &sc->sc_base);
error = wsmux_attach_sc(wsmux_getmux(mux), &sc->sc_base);
error = wsmux_attach_sc(wsmux_getmux(mux), &sc->sc_base);
sc = wsmux_getmux(unit);
sc = wsmux_getmux(unit);
struct wsmux_softc *wsmux_getmux(int);