mtd_read_user_prot_reg
ret = mtd_read_user_prot_reg(mtd, *ppos, len,
if (mtd_read_user_prot_reg(mtd, -1, 0, &retlen, NULL) ==
EXPORT_SYMBOL_GPL(mtd_read_user_prot_reg);
ret = mtd_read_user_prot_reg(mtd, offset, bytes, &retlen, val);
int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,