[PATCH] OneNAND: Simple Bad Block handling support

[Kyungmin Park <kyungmin.park@samsung.com>]

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Hi

As I mentioned before we want to use another bad block handling method.

But now we have to push OneNAND to official MTD not experimental
so I implement simple bad block table (BBT) routine
It's almost same as NAND does.
After merge. we have to split BBT into core and chip specific code.
As the first step, I add bad block header file (bbm.h). It has bad block
data structure, macro and etc.
I don't know which directory are used as bbt_core.c(?) location?

Please let me know how to use as official OneNAND MTD support and when?

Any comments are welcome.

Thank you.

Kyungmin Park

[-- Attachment #2: onenand-bbm.patch --]
[-- Type: application/octet-stream, Size: 19614 bytes --]

diff --git a/drivers/mtd/onenand/Makefile b/drivers/mtd/onenand/Makefile
--- a/drivers/mtd/onenand/Makefile
+++ b/drivers/mtd/onenand/Makefile
@@ -3,7 +3,9 @@
 #
 
 # Core functionality.
-obj-$(CONFIG_MTD_ONENAND)		+= onenand_base.o
+obj-$(CONFIG_MTD_ONENAND)		+= onenand.o
 
 # Board specific.
 obj-$(CONFIG_MTD_ONENAND_OMAP)		+= omap-onenand.o
+
+onenand-objs = onenand_base.o onenand_bbt.o
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -311,19 +311,21 @@ static int onenand_wait(struct mtd_info 
 	ctrl = this->read_word(this->base + ONENAND_REG_CTRL_STATUS);
 
 	if (ctrl & ONENAND_CTRL_ERROR) {
-		DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: controller error = 0x%04x", ctrl);
-		return -EAGAIN;
+		/* It maybe occur at initial bad block */
+		DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: controller error = 0x%04x\n", ctrl);
+		/* Clear other interrupt bits for preventing ECC error */
+		interrupt &= ONENAND_INT_MASTER;
 	}
 
 	if (ctrl & ONENAND_CTRL_LOCK) {
-		DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: it's locked error = 0x%04x", ctrl);
-		return -EIO;
+		DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: it's locked error = 0x%04x\n", ctrl);
+		return -EACCES;
 	}
 
 	if (interrupt & ONENAND_INT_READ) {
 		ecc = this->read_word(this->base + ONENAND_REG_ECC_STATUS);
 		if (ecc & ONENAND_ECC_2BIT_ALL) {
-			DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: ECC error = 0x%04x", ecc);
+			DEBUG(MTD_DEBUG_LEVEL0, "onenand_wait: ECC error = 0x%04x\n", ecc);
 			return -EBADMSG;
 		}
 	}
@@ -1060,6 +1062,25 @@ static int onenand_writev(struct mtd_inf
 }
 
 /**
+ * onenand_block_checkbad - [GENERIC] Check if a block is marked bad
+ * @param mtd		MTD device structure
+ * @param ofs		offset from device start
+ * @param getchip	0, if the chip is already selected
+ * @param allowbbt	1, if its allowed to access the bbt area
+ *
+ * Check, if the block is bad. Either by reading the bad block table or
+ * calling of the scan function.
+ */
+static int onenand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip, int allowbbt)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm = this->bbm;
+
+	/* Return info from the table */
+	return bbm->isbad_bbt(mtd, ofs, allowbbt);
+}
+
+/**
  * onenand_erase - [MTD Interface] erase block(s)
  * @param mtd		MTD device structure
  * @param instr		erase instruction
@@ -1109,7 +1130,12 @@ static int onenand_erase(struct mtd_info
 
 	while (len) {
 
-		/* TODO Check badblock */
+		/* Check if we have a bad block, we do not erase bad blocks */
+		if (onenand_block_checkbad(mtd, addr, 0, 0)) {
+			printk (KERN_WARNING "onenand_erase: attempt to erase a bad block at addr 0x%08x\n", (unsigned int) addr);
+			instr->state = MTD_ERASE_FAILED;
+			goto erase_exit;
+		}
 
 		this->command(mtd, ONENAND_CMD_ERASE, addr, block_size);
 
@@ -1161,34 +1187,70 @@ static void onenand_sync(struct mtd_info
 	onenand_release_device(mtd);
 }
 
+
 /**
  * onenand_block_isbad - [MTD Interface] Check whether the block at the given offset is bad
  * @param mtd		MTD device structure
  * @param ofs		offset relative to mtd start
+ *
+ * Check whether the block is bad
  */
 static int onenand_block_isbad(struct mtd_info *mtd, loff_t ofs)
 {
-	/*
-	 * TODO 
-	 * 1. Bad block table (BBT)
-	 *   -> using NAND BBT to support JFFS2
-	 * 2. Bad block management (BBM)
-	 *   -> bad block replace scheme
-	 *
-	 * Currently we do nothing
-	 */
-	return 0;
+	/* Check for invalid offset */
+	if (ofs > mtd->size)
+		return -EINVAL;
+
+	return onenand_block_checkbad(mtd, ofs, 1, 0);
+}
+
+/**
+ * onenand_default_block_markbad - [DEFAULT] mark a block bad
+ * @param mtd		MTD device structure
+ * @param ofs		offset from device start
+ *
+ * This is the default implementation, which can be overridden by
+ * a hardware specific driver.
+ */
+static int onenand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm = this->bbm;
+	u_char buf[2] = {0, 0};
+	size_t retlen;
+	int block;
+
+	/* Get block number */
+	block = ((int) ofs) >> bbm->bbt_erase_shift;
+        if (bbm->bbt)
+                bbm->bbt[block >> 2] |= 0x01 << ((block & 0x03) << 1);
+
+        /* We write two bytes, so we dont have to mess with 16 bit access */
+        ofs += mtd->oobsize + (bbm->badblockpos & ~0x01);
+        return mtd->write_oob(mtd, ofs , 2, &retlen, buf);
 }
 
 /**
  * onenand_block_markbad - [MTD Interface] Mark the block at the given offset as bad
  * @param mtd		MTD device structure
  * @param ofs		offset relative to mtd start
+ *
+ * Mark the block as bad
  */
 static int onenand_block_markbad(struct mtd_info *mtd, loff_t ofs)
 {
-	/* see above */
-	return 0;
+	struct onenand_chip *this = mtd->priv;
+	int ret;
+
+	ret = onenand_block_isbad(mtd, ofs);
+	if (ret) {
+		/* If it was bad already, return success and do nothing */
+		if (ret > 0)
+			return 0;
+		return ret;
+	}
+
+	return this->block_markbad(mtd, ofs);
 }
 
 /**
@@ -1411,6 +1473,11 @@ int onenand_scan(struct mtd_info *mtd, i
 	if (!this->write_bufferram)
 		this->write_bufferram = onenand_write_bufferram;
 
+	if (!this->block_markbad)
+		this->block_markbad = onenand_default_block_markbad;
+	if (!this->scan_bbt)
+		this->scan_bbt = onenand_default_bbt;
+
 	if (onenand_probe(mtd))
 		return -ENXIO;
 
@@ -1472,7 +1539,7 @@ int onenand_scan(struct mtd_info *mtd, i
 	/* Unlock whole block */
 	mtd->unlock(mtd, 0x0, this->chipsize);
 
-	return 0;
+	return this->scan_bbt(mtd);
 }
 
 /**
diff --git a/drivers/mtd/onenand/onenand_bbt.c b/drivers/mtd/onenand/onenand_bbt.c
new file mode 100644
--- /dev/null
+++ b/drivers/mtd/onenand/onenand_bbt.c
@@ -0,0 +1,246 @@
+/*
+ *  linux/drivers/mtd/onenand/onenand_bbt.c
+ *
+ *  Bad Block Table support for the OneNAND driver
+ *
+ *  Copyright(c) 2005 Samsung Electronics
+ *  Kyungmin Park <kyungmin.park@samsung.com>
+ *
+ *  Derived from nand_bbt.c
+ *
+ *  TODO:
+ *    Split BBT core and chip specific BBT.
+ */
+
+#include <linux/slab.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/onenand.h>
+#include <linux/mtd/compatmac.h>
+
+/**
+ * check_short_pattern - [GENERIC] check if a pattern is in the buffer
+ * @param buf		the buffer to search
+ * @param len		the length of buffer to search
+ * @param paglen	the pagelength
+ * @param td		search pattern descriptor
+ *
+ * Check for a pattern at the given place. Used to search bad block
+ * tables and good / bad block identifiers. Same as check_pattern, but
+ * no optional empty check and the pattern is expected to start
+ * at offset 0.
+ *
+ */
+static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
+{
+	int i;
+	uint8_t *p = buf;
+
+	/* Compare the pattern */
+	for (i = 0; i < td->len; i++) {
+		if (p[i] != td->pattern[i])
+			return -1;
+	}
+        return 0;
+}
+
+/**
+ * create_bbt - [GENERIC] Create a bad block table by scanning the device
+ * @param mtd		MTD device structure
+ * @param buf		temporary buffer
+ * @param bd		descriptor for the good/bad block search pattern
+ * @param chip		create the table for a specific chip, -1 read all chips.
+ *              Applies only if NAND_BBT_PERCHIP option is set
+ *
+ * Create a bad block table by scanning the device
+ * for the given good/bad block identify pattern
+ */
+static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm = this->bbm;
+	int i, j, numblocks, len, scanlen;
+	int startblock;
+	loff_t from;
+	size_t readlen, ooblen;
+
+	printk(KERN_INFO "Scanning device for bad blocks\n");
+
+	len = 1;
+
+	/* We need only read few bytes from the OOB area */
+	scanlen = ooblen = 0;
+	readlen = bd->len;
+
+	/* chip == -1 case only */
+	/* Note that numblocks is 2 * (real numblocks) here;
+	 * see i += 2 below as it makses shifting and masking less painful
+	 */
+	numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
+	startblock = 0;
+	from = 0;
+
+	for (i = startblock; i < numblocks; ) {
+		int ret;
+
+		for (j = 0; j < len; j++) {
+			size_t retlen;
+
+			/* No need to read pages fully,
+			 * just read required OOB bytes */
+			ret = mtd->read_oob(mtd, from + j * mtd->oobblock + bd->offs,
+						readlen, &retlen, &buf[0]);
+
+			if (ret)
+				return ret;
+
+			if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->oobblock, bd)) {
+				bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
+				printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
+					i >> 1, (unsigned int) from);
+				break;
+			}
+		}
+		i += 2;
+		from += (1 << bbm->bbt_erase_shift);
+	}
+
+	return 0;
+}
+
+
+/**
+ * onenand_memory_bbt - [GENERIC] create a memory based bad block table
+ * @param mtd		MTD device structure
+ * @param bd		descriptor for the good/bad block search pattern
+ *
+ * The function creates a memory based bbt by scanning the device
+ * for manufacturer / software marked good / bad blocks
+ */
+static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
+{
+	unsigned char data_buf[mtd->oobblock + mtd->oobsize];
+
+        bd->options &= ~NAND_BBT_SCANEMPTY;
+        return create_bbt(mtd, data_buf, bd, -1);
+}
+
+/**
+ * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
+ * @param mtd		MTD device structure
+ * @param offs		offset in the device
+ * @param allowbbt	allow access to bad block table region
+ */
+static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm = this->bbm;
+	int block;
+	uint8_t res;
+
+	/* Get block number * 2 */
+	block = (int) (offs >> (bbm->bbt_erase_shift - 1));
+	res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
+
+	DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
+		(unsigned int) offs, block >> 1, res);
+
+	switch ((int) res) {
+	case 0x00:	return 0;
+	case 0x01:	return 1;
+	case 0x02:	return allowbbt ? 0 : 1;
+	}
+
+	return 1;
+}
+
+/**
+ * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
+ * @param mtd		MTD device structure
+ * @param bd		descriptor for the good/bad block search pattern
+ *
+ * The function checks, if a bad block table(s) is/are already
+ * available. If not it scans the device for manufacturer
+ * marked good / bad blocks and writes the bad block table(s) to
+ * the selected place.
+ *
+ * The bad block table memory is allocated here. It must be freed
+ * by calling the onenand_free_bbt function.
+ *
+ */
+int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm = this->bbm;
+	int len, ret = 0;
+
+	len = mtd->size >> (this->erase_shift + 2);
+	/* Allocate memory (2bit per block) */
+	bbm->bbt = kmalloc(len, GFP_KERNEL);
+	if (!bbm->bbt) {
+		printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
+		return -ENOMEM;
+	}
+	/* Clear the memory bad block table */
+	memset(bbm->bbt, 0x00, len);
+
+	/* Set the bad block position */
+	bbm->badblockpos = ONENAND_BADBLOCK_POS;
+
+	/* Set erase shift */
+	bbm->bbt_erase_shift = this->erase_shift;
+
+	if (!bbm->isbad_bbt)
+		bbm->isbad_bbt = onenand_isbad_bbt;
+
+	/* Scan the device to build a memory based bad block table */
+	if ((ret = onenand_memory_bbt(mtd, bd))) {
+		printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
+		kfree(bbm->bbt);
+		bbm->bbt = NULL;
+	}
+
+	return ret;
+}
+
+/*
+ * Define some generic bad / good block scan pattern which are used
+ * while scanning a device for factory marked good / bad blocks.
+ */
+static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
+
+static struct nand_bbt_descr largepage_memorybased = {
+	.options = 0,
+	.offs = 0,
+	.len = 2,
+	.pattern = scan_ff_pattern,
+};
+
+/**
+ * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
+ * @param mtd		MTD device structure
+ *
+ * This function selects the default bad block table
+ * support for the device and calls the onenand_scan_bbt function
+ */
+int onenand_default_bbt(struct mtd_info *mtd)
+{
+	struct onenand_chip *this = mtd->priv;
+	struct bbm_info *bbm;
+
+	this->bbm = kmalloc(sizeof(struct bbm_info), GFP_KERNEL);
+	if (!this->bbm)
+		return -ENOMEM;
+
+	bbm = this->bbm;
+
+	memset(bbm, 0, sizeof(struct bbm_info));
+
+	/* 1KB page has same configuration as 2KB page */
+	if (!bbm->badblock_pattern)
+		bbm->badblock_pattern = &largepage_memorybased;
+
+	return onenand_scan_bbt(mtd, bbm->badblock_pattern);
+}
+
+EXPORT_SYMBOL(onenand_scan_bbt);
+EXPORT_SYMBOL(onenand_default_bbt);
diff --git a/include/linux/mtd/bbm.h b/include/linux/mtd/bbm.h
new file mode 100644
--- /dev/null
+++ b/include/linux/mtd/bbm.h
@@ -0,0 +1,122 @@
+/*
+ *  linux/include/linux/mtd/bbm.h
+ *
+ *  NAND family Bad Block Management (BBM) header file
+ *    - Bad Block Table (BBT) implementation
+ *
+ *  Copyright (c) 2005 Samsung Electronics
+ *  Kyungmin Park <kyungmin.park@samsung.com>
+ *
+ *  Copyright (c) 2000-2005
+ *  Thomas Gleixner <tglx@linuxtronix.de>
+ *
+ */
+#ifndef __LINUX_MTD_BBM_H
+#define __LINUX_MTD_BBM_H
+
+/* The maximum number of NAND chips in an array */
+#define NAND_MAX_CHIPS		8
+
+/**
+ * struct nand_bbt_descr - bad block table descriptor
+ * @param options	options for this descriptor
+ * @param pages		the page(s) where we find the bbt, used with
+ * 			option BBT_ABSPAGE when bbt is searched,
+ * 			then we store the found bbts pages here.
+ *			Its an array and supports up to 8 chips now
+ * @param offs		offset of the pattern in the oob area of the page
+ * @param veroffs	offset of the bbt version counter in the oob are of the page
+ * @param version	version read from the bbt page during scan
+ * @param len		length of the pattern, if 0 no pattern check is performed
+ * @param maxblocks	maximum number of blocks to search for a bbt. This number of
+ *			blocks is reserved at the end of the device 
+ *			where the tables are written.
+ * @param reserved_block_code	if non-0, this pattern denotes a reserved
+ *			(rather than bad) block in the stored bbt
+ * @param pattern	pattern to identify bad block table or factory marked
+ *			good / bad blocks, can be NULL, if len = 0
+ *
+ * Descriptor for the bad block table marker and the descriptor for the
+ * pattern which identifies good and bad blocks. The assumption is made
+ * that the pattern and the version count are always located in the oob area
+ * of the first block.
+ */
+struct nand_bbt_descr {
+	int options;
+	int pages[NAND_MAX_CHIPS];
+	int offs;
+	int veroffs;
+	uint8_t version[NAND_MAX_CHIPS];
+	int len;
+	int maxblocks;
+	int reserved_block_code;
+	uint8_t *pattern;
+};
+
+/* Options for the bad block table descriptors */
+
+/* The number of bits used per block in the bbt on the device */
+#define NAND_BBT_NRBITS_MSK	0x0000000F
+#define NAND_BBT_1BIT		0x00000001
+#define NAND_BBT_2BIT		0x00000002
+#define NAND_BBT_4BIT		0x00000004
+#define NAND_BBT_8BIT		0x00000008
+/* The bad block table is in the last good block of the device */
+#define NAND_BBT_LASTBLOCK	0x00000010
+/* The bbt is at the given page, else we must scan for the bbt */
+#define NAND_BBT_ABSPAGE	0x00000020
+/* The bbt is at the given page, else we must scan for the bbt */
+#define NAND_BBT_SEARCH		0x00000040
+/* bbt is stored per chip on multichip devices */
+#define NAND_BBT_PERCHIP	0x00000080
+/* bbt has a version counter at offset veroffs */
+#define NAND_BBT_VERSION	0x00000100
+/* Create a bbt if none axists */
+#define NAND_BBT_CREATE		0x00000200
+/* Search good / bad pattern through all pages of a block */
+#define NAND_BBT_SCANALLPAGES	0x00000400
+/* Scan block empty during good / bad block scan */
+#define NAND_BBT_SCANEMPTY	0x00000800
+/* Write bbt if neccecary */
+#define NAND_BBT_WRITE		0x00001000
+/* Read and write back block contents when writing bbt */
+#define NAND_BBT_SAVECONTENT	0x00002000
+/* Search good / bad pattern on the first and the second page */
+#define NAND_BBT_SCAN2NDPAGE	0x00004000
+
+/* The maximum number of blocks to scan for a bbt */
+#define NAND_BBT_SCAN_MAXBLOCKS	4
+
+/*
+ * Constants for oob configuration
+ */
+#define ONENAND_BADBLOCK_POS	0
+
+/**
+ * struct bbt_info - [GENERIC] Bad Block Table data structure
+ * @param bbt_erase_shift	[INTERN] number of address bits in a bbt entry
+ * @param badblockpos		[INTERN] position of the bad block marker in the oob area
+ * @param bbt			[INTERN] bad block table pointer
+ * @param badblock_pattern	[REPLACEABLE] bad block scan pattern used for initial bad block scan
+ * @param priv			[OPTIONAL] pointer to private bbm date
+ */
+struct bbm_info {
+	int bbt_erase_shift;
+	int badblockpos;
+	int options;
+
+	uint8_t *bbt;
+
+	int (*isbad_bbt)(struct mtd_info *mtd, loff_t ofs, int allowbbt);
+
+	/* TODO Add more NAND specific fileds */
+	struct nand_bbt_descr *badblock_pattern;
+
+	void *priv;
+};
+
+/* OneNAND BBT interface */
+extern int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd);
+extern int onenand_default_bbt(struct mtd_info *mtd);
+
+#endif	/* __LINUX_MTD_BBM_H */
diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
--- a/include/linux/mtd/onenand.h
+++ b/include/linux/mtd/onenand.h
@@ -14,6 +14,7 @@
 
 #include <linux/spinlock.h>
 #include <linux/mtd/onenand_regs.h>
+#include <linux/mtd/bbm.h>
 
 #define MAX_BUFFERRAM		2
 
@@ -67,10 +68,14 @@ struct onenand_bufferram {
  * @param wait		[REPLACEABLE] hardware specific function for wait on ready
  * @param read_bufferram	[REPLACEABLE] hardware specific function for BufferRAM Area
  * @param write_bufferram	[REPLACEABLE] hardware specific function for BufferRAM Area
+ * @param read_word	[REPLACEABLE] hardware specific function for read register of OneNAND
+ * @param write_word	[REPLACEABLE] hardware specific function for write register of OneNAND
+ * @param scan_bbt	[REPLACEALBE] hardware specific function for scaning Bad block Table
  * @param chip_lock	[INTERN] spinlock used to protect access to this structure and the chip
  * @param wq		[INTERN] wait queue to sleep on if a OneNAND operation is in progress
  * @param state		[INTERN] the current state of the OneNAND device
  * @param autooob	[REPLACEABLE] the default (auto)placement scheme
+ * @param bbm		[REPLACEABLE] pointer to Bad Block Management 
  * @param priv		[OPTIONAL] pointer to private chip date
  */
 struct onenand_chip {
@@ -96,6 +101,8 @@ struct onenand_chip {
 	unsigned short (*read_word)(void __iomem *addr);
 	void (*write_word)(unsigned short value, void __iomem *addr);
 	void (*mmcontrol)(struct mtd_info *mtd, int sync_read);
+	int (*block_markbad)(struct mtd_info *mtd, loff_t ofs);
+	int (*scan_bbt)(struct mtd_info *mtd);
 
 	spinlock_t		chip_lock;
 	wait_queue_head_t	wq;
@@ -103,6 +110,8 @@ struct onenand_chip {
 
 	struct nand_oobinfo	*autooob;
 
+	void 			*bbm;
+
 	void			*priv;
 };