RADEON_CLOCK_CNTL_DATA
(void)bus_read_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA);
data = bus_read_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA);
tmp = bus_read_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA);
(void)bus_read_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA);
bus_write_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA, val);
tmp = bus_read_4(sc->sc_memr, RADEON_CLOCK_CNTL_DATA);