RING_BUS_CTRL_A
outw(IO_SRAM_ENABLE, io + RING_BUS_CTRL_A);
outw(IO_SRAM_ENABLE | SERIAL_AC_LINK_ENABLE, io + RING_BUS_CTRL_A);
tmp = inw(io + RING_BUS_CTRL_A);
outw(RAC_SDFS_ENABLE|LAC_SDFS_ENABLE, io + RING_BUS_CTRL_A);
outw(tmp, io + RING_BUS_CTRL_A);