MM_NAND_CTL
writeb(ctl, cs553x->mmio + MM_NAND_CTL);
writeb(0, cs553x->mmio + MM_NAND_CTL);
writeb(0, cs553x->mmio + MM_NAND_CTL);
writeb(0, cs553x->mmio + MM_NAND_CTL);
writeb(CS_NAND_CTL_CE, cs553x->mmio + MM_NAND_CTL);