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>

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);