// SPDX-License-Identifier: GPL-2.0
//
// Driver for the SPI-NAND mode of Mediatek NAND Flash Interface
//
// Copyright (c) 2022 Chuanhong Guo <gch981213@gmail.com>
//
// This driver is based on the SPI-NAND mtd driver from Mediatek SDK:
//
// Copyright (C) 2020 MediaTek Inc.
// Author: Weijie Gao <weijie.gao@mediatek.com>
//
// This controller organize the page data as several interleaved sectors
// like the following: (sizeof(FDM + ECC) = snf->nfi_cfg.spare_size)
// +---------+------+------+---------+------+------+-----+
// | Sector1 | FDM1 | ECC1 | Sector2 | FDM2 | ECC2 | ... |
// +---------+------+------+---------+------+------+-----+
// With auto-format turned on, DMA only returns this part:
// +---------+---------+-----+
// | Sector1 | Sector2 | ... |
// +---------+---------+-----+
// The FDM data will be filled to the registers, and ECC parity data isn't
// accessible.
// With auto-format off, all ((Sector+FDM+ECC)*nsectors) will be read over DMA
// in it's original order shown in the first table. ECC can't be turned on when
// auto-format is off.
//
// However, Linux SPI-NAND driver expects the data returned as:
// +------+-----+
// | Page | OOB |
// +------+-----+
// where the page data is continuously stored instead of interleaved.
// So we assume all instructions matching the page_op template between ECC
// prepare_io_req and finish_io_req are for page cache r/w.
// Here's how this spi-mem driver operates when reading:
// 1. Always set snf->autofmt = true in prepare_io_req (even when ECC is off).
