mtd: nand: Add core infrastructure to deal with NAND devices

Add an intermediate layer to abstract NAND device interface so that
some logic can be shared between SPI NANDs, parallel/raw NANDs,
OneNANDs, ...

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

1 files changed, 731 insertions, 0 deletions

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
new file mode 100644
index 000000000000..792ea5c26329
--- /dev/null
+++ b/include/linux/mtd/nand.h
@@ -0,0 +1,731 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Copyright 2017 - Free Electrons
+ *
+ *  Authors:
+ *	Boris Brezillon <boris.brezillon@free-electrons.com>
+ *	Peter Pan <peterpandong@micron.com>
+ */
+
+#ifndef __LINUX_MTD_NAND_H
+#define __LINUX_MTD_NAND_H
+
+#include <linux/mtd/mtd.h>
+
+/**
+ * struct nand_memory_organization - Memory organization structure
+ * @bits_per_cell: number of bits per NAND cell
+ * @pagesize: page size
+ * @oobsize: OOB area size
+ * @pages_per_eraseblock: number of pages per eraseblock
+ * @eraseblocks_per_lun: number of eraseblocks per LUN (Logical Unit Number)
+ * @planes_per_lun: number of planes per LUN
+ * @luns_per_target: number of LUN per target (target is a synonym for die)
+ * @ntargets: total number of targets exposed by the NAND device
+ */
+struct nand_memory_organization {
+	unsigned int bits_per_cell;
+	unsigned int pagesize;
+	unsigned int oobsize;
+	unsigned int pages_per_eraseblock;
+	unsigned int eraseblocks_per_lun;
+	unsigned int planes_per_lun;
+	unsigned int luns_per_target;
+	unsigned int ntargets;
+};
+
+#define NAND_MEMORG(bpc, ps, os, ppe, epl, ppl, lpt, nt)	\
+	{							\
+		.bits_per_cell = (bpc),				\
+		.pagesize = (ps),				\
+		.oobsize = (os),				\
+		.pages_per_eraseblock = (ppe),			\
+		.eraseblocks_per_lun = (epl),			\
+		.planes_per_lun = (ppl),			\
+		.luns_per_target = (lpt),			\
+		.ntargets = (nt),				\
+	}
+
+/**
+ * struct nand_row_converter - Information needed to convert an absolute offset
+ *			       into a row address
+ * @lun_addr_shift: position of the LUN identifier in the row address
+ * @eraseblock_addr_shift: position of the eraseblock identifier in the row
+ *			   address
+ */
+struct nand_row_converter {
+	unsigned int lun_addr_shift;
+	unsigned int eraseblock_addr_shift;
+};
+
+/**
+ * struct nand_pos - NAND position object
+ * @target: the NAND target/die
+ * @lun: the LUN identifier
+ * @plane: the plane within the LUN
+ * @eraseblock: the eraseblock within the LUN
+ * @page: the page within the LUN
+ *
+ * These information are usually used by specific sub-layers to select the
+ * appropriate target/die and generate a row address to pass to the device.
+ */
+struct nand_pos {
+	unsigned int target;
+	unsigned int lun;
+	unsigned int plane;
+	unsigned int eraseblock;
+	unsigned int page;
+};
+
+/**
+ * struct nand_page_io_req - NAND I/O request object
+ * @pos: the position this I/O request is targeting
+ * @dataoffs: the offset within the page
+ * @datalen: number of data bytes to read from/write to this page
+ * @databuf: buffer to store data in or get data from
+ * @ooboffs: the OOB offset within the page
+ * @ooblen: the number of OOB bytes to read from/write to this page
+ * @oobbuf: buffer to store OOB data in or get OOB data from
+ *
+ * This object is used to pass per-page I/O requests to NAND sub-layers. This
+ * way all useful information are already formatted in a useful way and
+ * specific NAND layers can focus on translating these information into
+ * specific commands/operations.
+ */
+struct nand_page_io_req {
+	struct nand_pos pos;
+	unsigned int dataoffs;
+	unsigned int datalen;
+	union {
+		const void *out;
+		void *in;
+	} databuf;
+	unsigned int ooboffs;
+	unsigned int ooblen;
+	union {
+		const void *out;
+		void *in;
+	} oobbuf;
+};
+
+/**
+ * struct nand_ecc_req - NAND ECC requirements
+ * @strength: ECC strength
+ * @step_size: ECC step/block size
+ */
+struct nand_ecc_req {
+	unsigned int strength;
+	unsigned int step_size;
+};
+
+#define NAND_ECCREQ(str, stp) { .strength = (str), .step_size = (stp) }
+
+/**
+ * struct nand_bbt - bad block table object
+ * @cache: in memory BBT cache
+ */
+struct nand_bbt {
+	unsigned long *cache;
+};
+
+struct nand_device;
+
+/**
+ * struct nand_ops - NAND operations
+ * @erase: erase a specific block. No need to check if the block is bad before
+ *	   erasing, this has been taken care of by the generic NAND layer
+ * @markbad: mark a specific block bad. No need to check if the block is
+ *	     already marked bad, this has been taken care of by the generic
+ *	     NAND layer. This method should just write the BBM (Bad Block
+ *	     Marker) so that future call to struct_nand_ops->isbad() return
+ *	     true
+ * @isbad: check whether a block is bad or not. This method should just read
+ *	   the BBM and return whether the block is bad or not based on what it
+ *	   reads
+ *
+ * These are all low level operations that should be implemented by specialized
+ * NAND layers (SPI NAND, raw NAND, ...).
+ */
+struct nand_ops {
+	int (*erase)(struct nand_device *nand, const struct nand_pos *pos);
+	int (*markbad)(struct nand_device *nand, const struct nand_pos *pos);
+	bool (*isbad)(struct nand_device *nand, const struct nand_pos *pos);
+};
+
+/**
+ * struct nand_device - NAND device
+ * @mtd: MTD instance attached to the NAND device
+ * @memorg: memory layout
+ * @eccreq: ECC requirements
+ * @rowconv: position to row address converter
+ * @bbt: bad block table info
+ * @ops: NAND operations attached to the NAND device
+ *
+ * Generic NAND object. Specialized NAND layers (raw NAND, SPI NAND, OneNAND)
+ * should declare their own NAND object embedding a nand_device struct (that's
+ * how inheritance is done).
+ * struct_nand_device->memorg and struct_nand_device->eccreq should be filled
+ * at device detection time to reflect the NAND device
+ * capabilities/requirements. Once this is done nanddev_init() can be called.
+ * It will take care of converting NAND information into MTD ones, which means
+ * the specialized NAND layers should never manually tweak
+ * struct_nand_device->mtd except for the ->_read/write() hooks.
+ */
+struct nand_device {
+	struct mtd_info mtd;
+	struct nand_memory_organization memorg;
+	struct nand_ecc_req eccreq;
+	struct nand_row_converter rowconv;
+	struct nand_bbt bbt;
+	const struct nand_ops *ops;
+};
+
+/**
+ * struct nand_io_iter - NAND I/O iterator
+ * @req: current I/O request
+ * @oobbytes_per_page: maximum number of OOB bytes per page
+ * @dataleft: remaining number of data bytes to read/write
+ * @oobleft: remaining number of OOB bytes to read/write
+ *
+ * Can be used by specialized NAND layers to iterate over all pages covered
+ * by an MTD I/O request, which should greatly simplifies the boiler-plate
+ * code needed to read/write data from/to a NAND device.
+ */
+struct nand_io_iter {
+	struct nand_page_io_req req;
+	unsigned int oobbytes_per_page;
+	unsigned int dataleft;
+	unsigned int oobleft;
+};
+
+/**
+ * mtd_to_nanddev() - Get the NAND device attached to the MTD instance
+ * @mtd: MTD instance
+ *
+ * Return: the NAND device embedding @mtd.
+ */
+static inline struct nand_device *mtd_to_nanddev(struct mtd_info *mtd)
+{
+	return container_of(mtd, struct nand_device, mtd);
+}
+
+/**
+ * nanddev_to_mtd() - Get the MTD device attached to a NAND device
+ * @nand: NAND device
+ *
+ * Return: the MTD device embedded in @nand.
+ */
+static inline struct mtd_info *nanddev_to_mtd(struct nand_device *nand)
+{
+	return &nand->mtd;
+}
+
+/*
+ * nanddev_bits_per_cell() - Get the number of bits per cell
+ * @nand: NAND device
+ *
+ * Return: the number of bits per cell.
+ */
+static inline unsigned int nanddev_bits_per_cell(const struct nand_device *nand)
+{
+	return nand->memorg.bits_per_cell;
+}
+
+/**
+ * nanddev_page_size() - Get NAND page size
+ * @nand: NAND device
+ *
+ * Return: the page size.
+ */
+static inline size_t nanddev_page_size(const struct nand_device *nand)
+{
+	return nand->memorg.pagesize;
+}
+
+/**
+ * nanddev_per_page_oobsize() - Get NAND OOB size
+ * @nand: NAND device
+ *
+ * Return: the OOB size.
+ */
+static inline unsigned int
+nanddev_per_page_oobsize(const struct nand_device *nand)
+{
+	return nand->memorg.oobsize;
+}
+
+/**
+ * nanddev_pages_per_eraseblock() - Get the number of pages per eraseblock
+ * @nand: NAND device
+ *
+ * Return: the number of pages per eraseblock.
+ */
+static inline unsigned int
+nanddev_pages_per_eraseblock(const struct nand_device *nand)
+{
+	return nand->memorg.pages_per_eraseblock;
+}
+
+/**
+ * nanddev_per_page_oobsize() - Get NAND erase block size
+ * @nand: NAND device
+ *
+ * Return: the eraseblock size.
+ */
+static inline size_t nanddev_eraseblock_size(const struct nand_device *nand)
+{
+	return nand->memorg.pagesize * nand->memorg.pages_per_eraseblock;
+}
+
+/**
+ * nanddev_eraseblocks_per_lun() - Get the number of eraseblocks per LUN
+ * @nand: NAND device
+ *
+ * Return: the number of eraseblocks per LUN.
+ */
+static inline unsigned int
+nanddev_eraseblocks_per_lun(const struct nand_device *nand)
+{
+	return nand->memorg.eraseblocks_per_lun;
+}
+
+/**
+ * nanddev_target_size() - Get the total size provided by a single target/die
+ * @nand: NAND device
+ *
+ * Return: the total size exposed by a single target/die in bytes.
+ */
+static inline u64 nanddev_target_size(const struct nand_device *nand)
+{
+	return (u64)nand->memorg.luns_per_target *
+	       nand->memorg.eraseblocks_per_lun *
+	       nand->memorg.pages_per_eraseblock *
+	       nand->memorg.pagesize;
+}
+
+/**
+ * nanddev_ntarget() - Get the total of targets
+ * @nand: NAND device
+ *
+ * Return: the number of targets/dies exposed by @nand.
+ */
+static inline unsigned int nanddev_ntargets(const struct nand_device *nand)
+{
+	return nand->memorg.ntargets;
+}
+
+/**
+ * nanddev_neraseblocks() - Get the total number of erasablocks
+ * @nand: NAND device
+ *
+ * Return: the total number of eraseblocks exposed by @nand.
+ */
+static inline unsigned int nanddev_neraseblocks(const struct nand_device *nand)
+{
+	return (u64)nand->memorg.luns_per_target *
+	       nand->memorg.eraseblocks_per_lun *
+	       nand->memorg.pages_per_eraseblock;
+}
+
+/**
+ * nanddev_size() - Get NAND size
+ * @nand: NAND device
+ *
+ * Return: the total size (in bytes) exposed by @nand.
+ */
+static inline u64 nanddev_size(const struct nand_device *nand)
+{
+	return nanddev_target_size(nand) * nanddev_ntargets(nand);
+}
+
+/**
+ * nanddev_get_memorg() - Extract memory organization info from a NAND device
+ * @nand: NAND device
+ *
+ * This can be used by the upper layer to fill the memorg info before calling
+ * nanddev_init().
+ *
+ * Return: the memorg object embedded in the NAND device.
+ */
+static inline struct nand_memory_organization *
+nanddev_get_memorg(struct nand_device *nand)
+{
+	return &nand->memorg;
+}
+
+int nanddev_init(struct nand_device *nand, const struct nand_ops *ops,
+		 struct module *owner);
+void nanddev_cleanup(struct nand_device *nand);
+
+/**
+ * nanddev_register() - Register a NAND device
+ * @nand: NAND device
+ *
+ * Register a NAND device.
+ * This function is just a wrapper around mtd_device_register()
+ * registering the MTD device embedded in @nand.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+static inline int nanddev_register(struct nand_device *nand)
+{
+	return mtd_device_register(&nand->mtd, NULL, 0);
+}
+
+/**
+ * nanddev_unregister() - Unregister a NAND device
+ * @nand: NAND device
+ *
+ * Unregister a NAND device.
+ * This function is just a wrapper around mtd_device_unregister()
+ * unregistering the MTD device embedded in @nand.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+static inline int nanddev_unregister(struct nand_device *nand)
+{
+	return mtd_device_unregister(&nand->mtd);
+}
+
+/**
+ * nanddev_set_of_node() - Attach a DT node to a NAND device
+ * @nand: NAND device
+ * @np: DT node
+ *
+ * Attach a DT node to a NAND device.
+ */
+static inline void nanddev_set_of_node(struct nand_device *nand,
+				       struct device_node *np)
+{
+	mtd_set_of_node(&nand->mtd, np);
+}
+
+/**
+ * nanddev_get_of_node() - Retrieve the DT node attached to a NAND device
+ * @nand: NAND device
+ *
+ * Return: the DT node attached to @nand.
+ */
+static inline struct device_node *nanddev_get_of_node(struct nand_device *nand)
+{
+	return mtd_get_of_node(&nand->mtd);
+}
+
+/**
+ * nanddev_offs_to_pos() - Convert an absolute NAND offset into a NAND position
+ * @nand: NAND device
+ * @offs: absolute NAND offset (usually passed by the MTD layer)
+ * @pos: a NAND position object to fill in
+ *
+ * Converts @offs into a nand_pos representation.
+ *
+ * Return: the offset within the NAND page pointed by @pos.
+ */
+static inline unsigned int nanddev_offs_to_pos(struct nand_device *nand,
+					       loff_t offs,
+					       struct nand_pos *pos)
+{
+	unsigned int pageoffs;
+	u64 tmp = offs;
+
+	pageoffs = do_div(tmp, nand->memorg.pagesize);
+	pos->page = do_div(tmp, nand->memorg.pages_per_eraseblock);
+	pos->eraseblock = do_div(tmp, nand->memorg.eraseblocks_per_lun);
+	pos->plane = pos->eraseblock % nand->memorg.planes_per_lun;
+	pos->lun = do_div(tmp, nand->memorg.luns_per_target);
+	pos->target = tmp;
+
+	return pageoffs;
+}
+
+/**
+ * nanddev_pos_cmp() - Compare two NAND positions
+ * @a: First NAND position
+ * @b: Second NAND position
+ *
+ * Compares two NAND positions.
+ *
+ * Return: -1 if @a < @b, 0 if @a == @b and 1 if @a > @b.
+ */
+static inline int nanddev_pos_cmp(const struct nand_pos *a,
+				  const struct nand_pos *b)
+{
+	if (a->target != b->target)
+		return a->target < b->target ? -1 : 1;
+
+	if (a->lun != b->lun)
+		return a->lun < b->lun ? -1 : 1;
+
+	if (a->eraseblock != b->eraseblock)
+		return a->eraseblock < b->eraseblock ? -1 : 1;
+
+	if (a->page != b->page)
+		return a->page < b->page ? -1 : 1;
+
+	return 0;
+}
+
+/**
+ * nanddev_pos_to_offs() - Convert a NAND position into an absolute offset
+ * @nand: NAND device
+ * @pos: the NAND position to convert
+ *
+ * Converts @pos NAND position into an absolute offset.
+ *
+ * Return: the absolute offset. Note that @pos points to the beginning of a
+ *	   page, if one wants to point to a specific offset within this page
+ *	   the returned offset has to be adjusted manually.
+ */
+static inline loff_t nanddev_pos_to_offs(struct nand_device *nand,
+					 const struct nand_pos *pos)
+{
+	unsigned int npages;
+
+	npages = pos->page +
+		 ((pos->eraseblock +
+		   (pos->lun +
+		    (pos->target * nand->memorg.luns_per_target)) *
+		   nand->memorg.eraseblocks_per_lun) *
+		  nand->memorg.pages_per_eraseblock);
+
+	return (loff_t)npages * nand->memorg.pagesize;
+}
+
+/**
+ * nanddev_pos_to_row() - Extract a row address from a NAND position
+ * @nand: NAND device
+ * @pos: the position to convert
+ *
+ * Converts a NAND position into a row address that can then be passed to the
+ * device.
+ *
+ * Return: the row address extracted from @pos.
+ */
+static inline unsigned int nanddev_pos_to_row(struct nand_device *nand,
+					      const struct nand_pos *pos)
+{
+	return (pos->lun << nand->rowconv.lun_addr_shift) |
+	       (pos->eraseblock << nand->rowconv.eraseblock_addr_shift) |
+	       pos->page;
+}
+
+/**
+ * nanddev_pos_next_target() - Move a position to the next target/die
+ * @nand: NAND device
+ * @pos: the position to update
+ *
+ * Updates @pos to point to the start of the next target/die. Useful when you
+ * want to iterate over all targets/dies of a NAND device.
+ */
+static inline void nanddev_pos_next_target(struct nand_device *nand,
+					   struct nand_pos *pos)
+{
+	pos->page = 0;
+	pos->plane = 0;
+	pos->eraseblock = 0;
+	pos->lun = 0;
+	pos->target++;
+}
+
+/**
+ * nanddev_pos_next_lun() - Move a position to the next LUN
+ * @nand: NAND device
+ * @pos: the position to update
+ *
+ * Updates @pos to point to the start of the next LUN. Useful when you want to
+ * iterate over all LUNs of a NAND device.
+ */
+static inline void nanddev_pos_next_lun(struct nand_device *nand,
+					struct nand_pos *pos)
+{
+	if (pos->lun >= nand->memorg.luns_per_target - 1)
+		return nanddev_pos_next_target(nand, pos);
+
+	pos->lun++;
+	pos->page = 0;
+	pos->plane = 0;
+	pos->eraseblock = 0;
+}
+
+/**
+ * nanddev_pos_next_eraseblock() - Move a position to the next eraseblock
+ * @nand: NAND device
+ * @pos: the position to update
+ *
+ * Updates @pos to point to the start of the next eraseblock. Useful when you
+ * want to iterate over all eraseblocks of a NAND device.
+ */
+static inline void nanddev_pos_next_eraseblock(struct nand_device *nand,
+					       struct nand_pos *pos)
+{
+	if (pos->eraseblock >= nand->memorg.eraseblocks_per_lun - 1)
+		return nanddev_pos_next_lun(nand, pos);
+
+	pos->eraseblock++;
+	pos->page = 0;
+	pos->plane = pos->eraseblock % nand->memorg.planes_per_lun;
+}
+
+/**
+ * nanddev_pos_next_eraseblock() - Move a position to the next page
+ * @nand: NAND device
+ * @pos: the position to update
+ *
+ * Updates @pos to point to the start of the next page. Useful when you want to
+ * iterate over all pages of a NAND device.
+ */
+static inline void nanddev_pos_next_page(struct nand_device *nand,
+					 struct nand_pos *pos)
+{
+	if (pos->page >= nand->memorg.pages_per_eraseblock - 1)
+		return nanddev_pos_next_eraseblock(nand, pos);
+
+	pos->page++;
+}
+
+/**
+ * nand_io_iter_init - Initialize a NAND I/O iterator
+ * @nand: NAND device
+ * @offs: absolute offset
+ * @req: MTD request
+ * @iter: NAND I/O iterator
+ *
+ * Initializes a NAND iterator based on the information passed by the MTD
+ * layer.
+ */
+static inline void nanddev_io_iter_init(struct nand_device *nand,
+					loff_t offs, struct mtd_oob_ops *req,
+					struct nand_io_iter *iter)
+{
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+
+	iter->req.dataoffs = nanddev_offs_to_pos(nand, offs, &iter->req.pos);
+	iter->req.ooboffs = req->ooboffs;
+	iter->oobbytes_per_page = mtd_oobavail(mtd, req);
+	iter->dataleft = req->len;
+	iter->oobleft = req->ooblen;
+	iter->req.databuf.in = req->datbuf;
+	iter->req.datalen = min_t(unsigned int,
+				  nand->memorg.pagesize - iter->req.dataoffs,
+				  iter->dataleft);
+	iter->req.oobbuf.in = req->oobbuf;
+	iter->req.ooblen = min_t(unsigned int,
+				 iter->oobbytes_per_page - iter->req.ooboffs,
+				 iter->oobleft);
+}
+
+/**
+ * nand_io_iter_next_page - Move to the next page
+ * @nand: NAND device
+ * @iter: NAND I/O iterator
+ *
+ * Updates the @iter to point to the next page.
+ */
+static inline void nanddev_io_iter_next_page(struct nand_device *nand,
+					     struct nand_io_iter *iter)
+{
+	nanddev_pos_next_page(nand, &iter->req.pos);
+	iter->dataleft -= iter->req.datalen;
+	iter->req.databuf.in += iter->req.datalen;
+	iter->oobleft -= iter->req.ooblen;
+	iter->req.oobbuf.in += iter->req.ooblen;
+	iter->req.dataoffs = 0;
+	iter->req.ooboffs = 0;
+	iter->req.datalen = min_t(unsigned int, nand->memorg.pagesize,
+				  iter->dataleft);
+	iter->req.ooblen = min_t(unsigned int, iter->oobbytes_per_page,
+				 iter->oobleft);
+}
+
+/**
+ * nand_io_iter_end - Should end iteration or not
+ * @nand: NAND device
+ * @iter: NAND I/O iterator
+ *
+ * Check whether @iter has reached the end of the NAND portion it was asked to
+ * iterate on or not.
+ *
+ * Return: true if @iter has reached the end of the iteration request, false
+ *	   otherwise.
+ */
+static inline bool nanddev_io_iter_end(struct nand_device *nand,
+				       const struct nand_io_iter *iter)
+{
+	if (iter->dataleft || iter->oobleft)
+		return false;
+
+	return true;
+}
+
+/**
+ * nand_io_for_each_page - Iterate over all NAND pages contained in an MTD I/O
+ *			   request
+ * @nand: NAND device
+ * @start: start address to read/write from
+ * @req: MTD I/O request
+ * @iter: NAND I/O iterator
+ *
+ * Should be used for iterate over pages that are contained in an MTD request.
+ */
+#define nanddev_io_for_each_page(nand, start, req, iter)		\
+	for (nanddev_io_iter_init(nand, start, req, iter);		\
+	     !nanddev_io_iter_end(nand, iter);				\
+	     nanddev_io_iter_next_page(nand, iter))
+
+bool nanddev_isbad(struct nand_device *nand, const struct nand_pos *pos);
+bool nanddev_isreserved(struct nand_device *nand, const struct nand_pos *pos);
+int nanddev_erase(struct nand_device *nand, const struct nand_pos *pos);
+int nanddev_markbad(struct nand_device *nand, const struct nand_pos *pos);
+
+/* BBT related functions */
+enum nand_bbt_block_status {
+	NAND_BBT_BLOCK_STATUS_UNKNOWN,
+	NAND_BBT_BLOCK_GOOD,
+	NAND_BBT_BLOCK_WORN,
+	NAND_BBT_BLOCK_RESERVED,
+	NAND_BBT_BLOCK_FACTORY_BAD,
+	NAND_BBT_BLOCK_NUM_STATUS,
+};
+
+int nanddev_bbt_init(struct nand_device *nand);
+void nanddev_bbt_cleanup(struct nand_device *nand);
+int nanddev_bbt_update(struct nand_device *nand);
+int nanddev_bbt_get_block_status(const struct nand_device *nand,
+				 unsigned int entry);
+int nanddev_bbt_set_block_status(struct nand_device *nand, unsigned int entry,
+				 enum nand_bbt_block_status status);
+int nanddev_bbt_markbad(struct nand_device *nand, unsigned int block);
+
+/**
+ * nanddev_bbt_pos_to_entry() - Convert a NAND position into a BBT entry
+ * @nand: NAND device
+ * @pos: the NAND position we want to get BBT entry for
+ *
+ * Return the BBT entry used to store information about the eraseblock pointed
+ * by @pos.
+ *
+ * Return: the BBT entry storing information about eraseblock pointed by @pos.
+ */
+static inline unsigned int nanddev_bbt_pos_to_entry(struct nand_device *nand,
+						    const struct nand_pos *pos)
+{
+	return pos->eraseblock +
+	       ((pos->lun + (pos->target * nand->memorg.luns_per_target)) *
+		nand->memorg.eraseblocks_per_lun);
+}
+
+/**
+ * nanddev_bbt_is_initialized() - Check if the BBT has been initialized
+ * @nand: NAND device
+ *
+ * Return: true if the BBT has been initialized, false otherwise.
+ */
+static inline bool nanddev_bbt_is_initialized(struct nand_device *nand)
+{
+	return !!nand->bbt.cache;
+}
+
+/* MTD -> NAND helper functions. */
+int nanddev_mtd_erase(struct mtd_info *mtd, struct erase_info *einfo);
+
+#endif /* __LINUX_MTD_NAND_H */