sf2r_read_register
u_int32_t sf2r_read_register(bus_space_tag_t, bus_space_handle_t, bus_size_t);
sc->tea.read = sf2r_read_register;
sc.tea.read = sf2r_read_register;
freq = sf2r_read_register(iot, ioh, sc.tea.offset);
buf = sf2r_read_register(sc->tea.iot, sc->tea.ioh, sc->tea.offset);