LOONGSON_NAND_CMD
writel(op->cmd_reg, host->reg_base + LOONGSON_NAND_CMD);
regmap_write_bits(host->regmap, LOONGSON_NAND_CMD, LOONGSON_NAND_CMD_VALID,
ret = regmap_read_poll_timeout(host->regmap, LOONGSON_NAND_CMD,