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>

4 files changed, 380 insertions, 0 deletions

diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 6d53734..1c1a1f4 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -1 +1,4 @@
+config MTD_NAND_CORE
+	tristate
+
 source "drivers/mtd/nand/raw/Kconfig"
diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index 32af716..a72d3cb 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -1,3 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
+nandcore-objs := core.o bbt.o
+obj-$(CONFIG_MTD_NAND_CORE) += nandcore.o
+
 obj-y	+= raw/
diff --git a/drivers/mtd/nand/bbt.c b/drivers/mtd/nand/bbt.c
new file mode 100644
index 0000000..56cde38
--- /dev/null
+++ b/drivers/mtd/nand/bbt.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017 Free Electrons
+ *
+ * Authors:
+ *	Boris Brezillon <boris.brezillon@free-electrons.com>
+ *	Peter Pan <peterpandong@micron.com>
+ */
+
+#define pr_fmt(fmt)	"nand-bbt: " fmt
+
+#include <linux/mtd/nand.h>
+#include <linux/slab.h>
+
+/**
+ * nanddev_bbt_init() - Initialize the BBT (Bad Block Table)
+ * @nand: NAND device
+ *
+ * Initialize the in-memory BBT.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_bbt_init(struct nand_device *nand)
+{
+	unsigned int bits_per_block = fls(NAND_BBT_BLOCK_NUM_STATUS);
+	unsigned int nblocks = nanddev_neraseblocks(nand);
+	unsigned int nwords = DIV_ROUND_UP(nblocks * bits_per_block,
+					   BITS_PER_LONG);
+
+	nand->bbt.cache = kzalloc(nwords, GFP_KERNEL);
+	if (!nand->bbt.cache)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nanddev_bbt_init);
+
+/**
+ * nanddev_bbt_cleanup() - Cleanup the BBT (Bad Block Table)
+ * @nand: NAND device
+ *
+ * Undoes what has been done in nanddev_bbt_init()
+ */
+void nanddev_bbt_cleanup(struct nand_device *nand)
+{
+	kfree(nand->bbt.cache);
+}
+EXPORT_SYMBOL_GPL(nanddev_bbt_cleanup);
+
+/**
+ * nanddev_bbt_update() - Update a BBT
+ * @nand: nand device
+ *
+ * Update the BBT. Currently a NOP function since on-flash bbt is not yet
+ * supported.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_bbt_update(struct nand_device *nand)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nanddev_bbt_update);
+
+/**
+ * nanddev_bbt_get_block_status() - Return the status of an eraseblock
+ * @nand: nand device
+ * @entry: the BBT entry
+ *
+ * Return: a positive number nand_bbt_block_status status or -%ERANGE if @entry
+ *	   is bigger than the BBT size.
+ */
+int nanddev_bbt_get_block_status(const struct nand_device *nand,
+				 unsigned int entry)
+{
+	unsigned int bits_per_block = fls(NAND_BBT_BLOCK_NUM_STATUS);
+	unsigned long *pos = nand->bbt.cache +
+			     ((entry * bits_per_block) / BITS_PER_LONG);
+	unsigned int offs = (entry * bits_per_block) % BITS_PER_LONG;
+	unsigned long status;
+
+	if (entry >= nanddev_neraseblocks(nand))
+		return -ERANGE;
+
+	status = pos[0] >> offs;
+	if (bits_per_block + offs > BITS_PER_LONG)
+		status |= pos[1] << (BITS_PER_LONG - offs);
+
+	return status & GENMASK(bits_per_block - 1, 0);
+}
+EXPORT_SYMBOL_GPL(nanddev_bbt_get_block_status);
+
+/**
+ * nanddev_bbt_set_block_status() - Update the status of an eraseblock in the
+ *				    in-memory BBT
+ * @nand: nand device
+ * @entry: the BBT entry to update
+ * @status: the new status
+ *
+ * Update an entry of the in-memory BBT. If you want to push the updated BBT
+ * the NAND you should call nanddev_bbt_update().
+ *
+ * Return: 0 in case of success or -%ERANGE if @entry is bigger than the BBT
+ *	   size.
+ */
+int nanddev_bbt_set_block_status(struct nand_device *nand, unsigned int entry,
+				 enum nand_bbt_block_status status)
+{
+	unsigned int bits_per_block = fls(NAND_BBT_BLOCK_NUM_STATUS);
+	unsigned long *pos = nand->bbt.cache +
+			     ((entry * bits_per_block) / BITS_PER_LONG);
+	unsigned int offs = (entry * bits_per_block) % BITS_PER_LONG;
+	unsigned long val = status & GENMASK(bits_per_block - 1, 0);
+
+	if (entry >= nanddev_neraseblocks(nand))
+		return -ERANGE;
+
+	pos[0] &= ~GENMASK(offs + bits_per_block - 1, offs);
+	pos[0] |= val << offs;
+
+	if (bits_per_block + offs > BITS_PER_LONG) {
+		unsigned int rbits = bits_per_block + offs - BITS_PER_LONG;
+
+		pos[1] &= ~GENMASK(rbits - 1, 0);
+		pos[1] |= val >> rbits;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nanddev_bbt_set_block_status);
diff --git a/drivers/mtd/nand/core.c b/drivers/mtd/nand/core.c
new file mode 100644
index 0000000..f237a68
--- /dev/null
+++ b/drivers/mtd/nand/core.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017 Free Electrons
+ *
+ * Authors:
+ *	Boris Brezillon <boris.brezillon@free-electrons.com>
+ *	Peter Pan <peterpandong@micron.com>
+ */
+
+#define pr_fmt(fmt)	"nand: " fmt
+
+#include <linux/module.h>
+#include <linux/mtd/nand.h>
+
+/**
+ * nanddev_isbad() - Check if a block is bad
+ * @nand: NAND device
+ * @pos: position pointing to the block we want to check
+ *
+ * Return: true if the block is bad, false otherwise.
+ */
+bool nanddev_isbad(struct nand_device *nand, const struct nand_pos *pos)
+{
+	if (nanddev_bbt_is_initialized(nand)) {
+		unsigned int entry;
+		int status;
+
+		entry = nanddev_bbt_pos_to_entry(nand, pos);
+		status = nanddev_bbt_get_block_status(nand, entry);
+		/* Lazy block status retrieval */
+		if (status == NAND_BBT_BLOCK_STATUS_UNKNOWN) {
+			if (nand->ops->isbad(nand, pos))
+				status = NAND_BBT_BLOCK_FACTORY_BAD;
+			else
+				status = NAND_BBT_BLOCK_GOOD;
+
+			nanddev_bbt_set_block_status(nand, entry, status);
+		}
+
+		if (status == NAND_BBT_BLOCK_WORN ||
+		    status == NAND_BBT_BLOCK_FACTORY_BAD)
+			return true;
+
+		return false;
+	}
+
+	return nand->ops->isbad(nand, pos);
+}
+EXPORT_SYMBOL_GPL(nanddev_isbad);
+
+/**
+ * nanddev_markbad() - Mark a block as bad
+ * @nand: NAND device
+ * @block: block to mark bad
+ *
+ * Mark a block bad. This function is updating the BBT if available and
+ * calls the low-level markbad hook (nand->ops->markbad()).
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_markbad(struct nand_device *nand, const struct nand_pos *pos)
+{
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	unsigned int entry;
+	int ret = 0;
+
+	if (nanddev_isbad(nand, pos))
+		return 0;
+
+	ret = nand->ops->markbad(nand, pos);
+	if (ret)
+		pr_warn("failed to write BBM to block @%llx (err = %d)\n",
+			nanddev_pos_to_offs(nand, pos), ret);
+
+	if (!nanddev_bbt_is_initialized(nand))
+		goto out;
+
+	entry = nanddev_bbt_pos_to_entry(nand, pos);
+	ret = nanddev_bbt_set_block_status(nand, entry, NAND_BBT_BLOCK_WORN);
+	if (ret)
+		goto out;
+
+	ret = nanddev_bbt_update(nand);
+
+out:
+	if (!ret)
+		mtd->ecc_stats.badblocks++;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nanddev_markbad);
+
+/**
+ * nanddev_isreserved() - Check whether an eraseblock is reserved or not
+ * @nand: NAND device
+ * @pos: NAND position to test
+ *
+ * Checks whether the eraseblock pointed by @pos is reserved or not.
+ *
+ * Return: true if the eraseblock is reserved, false otherwise.
+ */
+bool nanddev_isreserved(struct nand_device *nand, const struct nand_pos *pos)
+{
+	unsigned int entry;
+	int status;
+
+	if (!nanddev_bbt_is_initialized(nand))
+		return false;
+
+	/* Return info from the table */
+	entry = nanddev_bbt_pos_to_entry(nand, pos);
+	status = nanddev_bbt_get_block_status(nand, entry);
+	return status == NAND_BBT_BLOCK_RESERVED;
+}
+EXPORT_SYMBOL_GPL(nanddev_isreserved);
+
+/**
+ * nanddev_erase() - Erase a NAND portion
+ * @nand: NAND device
+ * @block: eraseblock to erase
+ *
+ * Erases @block if it's not bad.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_erase(struct nand_device *nand, const struct nand_pos *pos)
+{
+	if (nanddev_isbad(nand, pos) || nanddev_isreserved(nand, pos)) {
+		pr_warn("attempt to erase a bad/reserved block @%llx\n",
+			nanddev_pos_to_offs(nand, pos));
+		return -EIO;
+	}
+
+	return nand->ops->erase(nand, pos);
+}
+EXPORT_SYMBOL_GPL(nanddev_erase);
+
+/**
+ * nanddev_mtd_erase() - Generic mtd->_erase() implementation for NAND devices
+ * @mtd: MTD device
+ * @einfo: erase request
+ *
+ * This is a simple mtd->_erase() implementation iterating over all blocks
+ * concerned by @einfo and calling nand->ops->erase() on each of them.
+ *
+ * Note that mtd->_erase should not be directly assigned to this helper,
+ * because there's no locking here. NAND specialized layers should instead
+ * implement there own wrapper around nanddev_mtd_erase() taking the
+ * appropriate lock before calling nanddev_mtd_erase().
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_mtd_erase(struct mtd_info *mtd, struct erase_info *einfo)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	struct nand_pos pos, last;
+	int ret;
+
+	nanddev_offs_to_pos(nand, einfo->addr, &pos);
+	nanddev_offs_to_pos(nand, einfo->addr + einfo->len - 1, &last);
+	while (nanddev_pos_cmp(&pos, &last) <= 0) {
+		ret = nanddev_erase(nand, &pos);
+		if (ret) {
+			einfo->fail_addr = nanddev_pos_to_offs(nand, &pos);
+			einfo->state = MTD_ERASE_FAILED;
+
+			return ret;
+		}
+
+		nanddev_pos_next_eraseblock(nand, &pos);
+	}
+
+	einfo->state = MTD_ERASE_DONE;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nanddev_mtd_erase);
+
+/**
+ * nanddev_init() - Initialize a NAND device
+ * @nand: NAND device
+ * @memorg: NAND memory organization descriptor
+ * @ops: NAND device operations
+ *
+ * Initializes a NAND device object. Consistency checks are done on @memorg and
+ * @ops. Also takes care of initializing the BBT.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int nanddev_init(struct nand_device *nand, const struct nand_ops *ops,
+		 struct module *owner)
+{
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	struct nand_memory_organization *memorg = nanddev_get_memorg(nand);
+
+	if (!nand || !ops)
+		return -EINVAL;
+
+	if (!ops->erase || !ops->markbad || !ops->isbad)
+		return -EINVAL;
+
+	if (!memorg->bits_per_cell || !memorg->pagesize ||
+	    !memorg->pages_per_eraseblock || !memorg->eraseblocks_per_lun ||
+	    !memorg->planes_per_lun || !memorg->luns_per_target ||
+	    !memorg->ntargets)
+		return -EINVAL;
+
+	nand->rowconv.eraseblock_addr_shift =
+					fls(memorg->pages_per_eraseblock - 1);
+	nand->rowconv.lun_addr_shift = fls(memorg->eraseblocks_per_lun - 1) +
+				       nand->rowconv.eraseblock_addr_shift;
+
+	nand->ops = ops;
+
+	mtd->type = memorg->bits_per_cell == 1 ?
+		    MTD_NANDFLASH : MTD_MLCNANDFLASH;
+	mtd->flags = MTD_CAP_NANDFLASH;
+	mtd->erasesize = memorg->pagesize * memorg->pages_per_eraseblock;
+	mtd->writesize = memorg->pagesize;
+	mtd->writebufsize = memorg->pagesize;
+	mtd->oobsize = memorg->oobsize;
+	mtd->size = nanddev_size(nand);
+	mtd->owner = owner;
+
+	return nanddev_bbt_init(nand);
+}
+EXPORT_SYMBOL_GPL(nanddev_init);
+
+/**
+ * nanddev_cleanup() - Release resources allocated in nanddev_init()
+ * @nand: NAND device
+ *
+ * Basically undoes what has been done in nanddev_init().
+ */
+void nanddev_cleanup(struct nand_device *nand)
+{
+	if (nanddev_bbt_is_initialized(nand))
+		nanddev_bbt_cleanup(nand);
+}
+EXPORT_SYMBOL_GPL(nanddev_cleanup);
+
+MODULE_DESCRIPTION("Generic NAND framework");
+MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
+MODULE_LICENSE("GPL v2");