mbus_rr_2
void mbus_rr_2(void *, bus_space_handle_t, bus_size_t, uint16_t *, bus_size_t);
mbus_rr_1, mbus_rr_2, mbus_rr_4, mbus_rr_8,
mbus_rr_2, mbus_rr_4, mbus_rr_8,