nand_bbt.c 38.7 KB
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/*
 *  drivers/mtd/nand_bbt.c
 *
 *  Overview:
 *   Bad block table support for the NAND driver
 *
 *  Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Description:
 *
 * When nand_scan_bbt is called, then it tries to find the bad block table
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 * depending on the options in the BBT descriptor(s). If no flash based BBT
 * (NAND_USE_FLASH_BBT) is specified then the device is scanned for factory
 * marked good / bad blocks. This information is used to create a memory BBT.
 * Once a new bad block is discovered then the "factory" information is updated
 * on the device.
 * If a flash based BBT is specified then the function first tries to find the
 * BBT on flash. If a BBT is found then the contents are read and the memory
 * based BBT is created. If a mirrored BBT is selected then the mirror is
 * searched too and the versions are compared. If the mirror has a greater
 * version number than the mirror BBT is used to build the memory based BBT.
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 * If the tables are not versioned, then we "or" the bad block information.
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 * If one of the BBTs is out of date or does not exist it is (re)created.
 * If no BBT exists at all then the device is scanned for factory marked
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 * good / bad blocks and the bad block tables are created.
 *
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 * For manufacturer created BBTs like the one found on M-SYS DOC devices
 * the BBT is searched and read but never created
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 *
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 * The auto generated bad block table is located in the last good blocks
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 * of the device. The table is mirrored, so it can be updated eventually.
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 * The table is marked in the OOB area with an ident pattern and a version
 * number which indicates which of both tables is more up to date. If the NAND
 * controller needs the complete OOB area for the ECC information then the
 * option NAND_USE_FLASH_BBT_NO_OOB should be used: it moves the ident pattern
 * and the version byte into the data area and the OOB area will remain
 * untouched.
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 *
 * The table uses 2 bits per block
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 * 11b:		block is good
 * 00b:		block is factory marked bad
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 * 01b, 10b:	block is marked bad due to wear
 *
 * The memory bad block table uses the following scheme:
 * 00b:		block is good
 * 01b:		block is marked bad due to wear
 * 10b:		block is reserved (to protect the bbt area)
 * 11b:		block is factory marked bad
 *
 * Multichip devices like DOC store the bad block info per floor.
 *
 * Following assumptions are made:
 * - bbts start at a page boundary, if autolocated on a block boundary
 * - the space necessary for a bbt in FLASH does not exceed a block boundary
 *
 */

#include <common.h>
#include <malloc.h>
#include <linux/mtd/compat.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
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#include <linux/mtd/nand_ecc.h>
#include <linux/bitops.h>
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#include <asm/errno.h>

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static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
{
	int ret;

	ret = memcmp(buf, td->pattern, td->len);
	if (!ret)
		return ret;
	return -1;
}
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/**
 * check_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf:	the buffer to search
 * @len:	the length of buffer to search
 * @paglen:	the pagelength
 * @td:		search pattern descriptor
 *
 * Check for a pattern at the given place. Used to search bad block
 * tables and good / bad block identifiers.
 * If the SCAN_EMPTY option is set then check, if all bytes except the
 * pattern area contain 0xff
 *
*/
static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
{
	int i, end = 0;
	uint8_t *p = buf;

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	if (td->options & NAND_BBT_NO_OOB)
		return check_pattern_no_oob(buf, td);

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	end = paglen + td->offs;
	if (td->options & NAND_BBT_SCANEMPTY) {
		for (i = 0; i < end; i++) {
			if (p[i] != 0xff)
				return -1;
		}
	}
	p += end;

	/* Compare the pattern */
	for (i = 0; i < td->len; i++) {
		if (p[i] != td->pattern[i])
			return -1;
	}

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	/* Check both positions 1 and 6 for pattern? */
	if (td->options & NAND_BBT_SCANBYTE1AND6) {
		if (td->options & NAND_BBT_SCANEMPTY) {
			p += td->len;
			end += NAND_SMALL_BADBLOCK_POS - td->offs;
			/* Check region between positions 1 and 6 */
			for (i = 0; i < NAND_SMALL_BADBLOCK_POS - td->offs - td->len;
					i++) {
				if (*p++ != 0xff)
					return -1;
			}
		}
		else {
			p += NAND_SMALL_BADBLOCK_POS - td->offs;
		}
		/* Compare the pattern */
		for (i = 0; i < td->len; i++) {
			if (p[i] != td->pattern[i])
				return -1;
		}
	}

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	if (td->options & NAND_BBT_SCANEMPTY) {
		p += td->len;
		end += td->len;
		for (i = end; i < len; i++) {
			if (*p++ != 0xff)
				return -1;
		}
	}
	return 0;
}

/**
 * check_short_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf:	the buffer to search
 * @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
 *
*/
static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
{
	int i;
	uint8_t *p = buf;

	/* Compare the pattern */
	for (i = 0; i < td->len; i++) {
		if (p[td->offs + i] != td->pattern[i])
			return -1;
	}
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	/* Need to check location 1 AND 6? */
	if (td->options & NAND_BBT_SCANBYTE1AND6) {
		for (i = 0; i < td->len; i++) {
			if (p[NAND_SMALL_BADBLOCK_POS + i] != td->pattern[i])
				return -1;
		}
	}
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	return 0;
}

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/**
 * add_marker_len - compute the length of the marker in data area
 * @td:		BBT descriptor used for computation
 *
 * The length will be 0 if the markeris located in OOB area.
 */
static u32 add_marker_len(struct nand_bbt_descr *td)
{
	u32 len;

	if (!(td->options & NAND_BBT_NO_OOB))
		return 0;

	len = td->len;
	if (td->options & NAND_BBT_VERSION)
		len++;
	return len;
}

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/**
 * read_bbt - [GENERIC] Read the bad block table starting from page
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @page:	the starting page
 * @num:	the number of bbt descriptors to read
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 * @td:		the bbt describtion table
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 * @offs:	offset in the memory table
 *
 * Read the bad block table starting from page.
 *
 */
static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
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		struct nand_bbt_descr *td, int offs)
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{
	int res, i, j, act = 0;
	struct nand_chip *this = mtd->priv;
	size_t retlen, len, totlen;
	loff_t from;
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	int bits = td->options & NAND_BBT_NRBITS_MSK;
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	uint8_t msk = (uint8_t) ((1 << bits) - 1);
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	u32 marker_len;
	int reserved_block_code = td->reserved_block_code;
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	totlen = (num * bits) >> 3;
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	marker_len = add_marker_len(td);
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	from = ((loff_t) page) << this->page_shift;

	while (totlen) {
		len = min(totlen, (size_t) (1 << this->bbt_erase_shift));
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		if (marker_len) {
			/*
			 * In case the BBT marker is not in the OOB area it
			 * will be just in the first page.
			 */
			len -= marker_len;
			from += marker_len;
			marker_len = 0;
		}
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		res = mtd->read(mtd, from, len, &retlen, buf);
		if (res < 0) {
			if (retlen != len) {
				printk(KERN_INFO "nand_bbt: Error reading bad block table\n");
				return res;
			}
			printk(KERN_WARNING "nand_bbt: ECC error while reading bad block table\n");
		}

		/* Analyse data */
		for (i = 0; i < len; i++) {
			uint8_t dat = buf[i];
			for (j = 0; j < 8; j += bits, act += 2) {
				uint8_t tmp = (dat >> j) & msk;
				if (tmp == msk)
					continue;
				if (reserved_block_code && (tmp == reserved_block_code)) {
					printk(KERN_DEBUG "nand_read_bbt: Reserved block at 0x%012llx\n",
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					       (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
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					this->bbt[offs + (act >> 3)] |= 0x2 << (act & 0x06);
					mtd->ecc_stats.bbtblocks++;
					continue;
				}
				/* Leave it for now, if its matured we can move this
				 * message to MTD_DEBUG_LEVEL0 */
				printk(KERN_DEBUG "nand_read_bbt: Bad block at 0x%012llx\n",
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				       (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
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				/* Factory marked bad or worn out ? */
				if (tmp == 0)
					this->bbt[offs + (act >> 3)] |= 0x3 << (act & 0x06);
				else
					this->bbt[offs + (act >> 3)] |= 0x1 << (act & 0x06);
				mtd->ecc_stats.badblocks++;
			}
		}
		totlen -= len;
		from += len;
	}
	return 0;
}

/**
 * read_abs_bbt - [GENERIC] Read the bad block table starting at a given page
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table
 * @chip:	read the table for a specific chip, -1 read all chips.
 *		Applies only if NAND_BBT_PERCHIP option is set
 *
 * Read the bad block table for all chips starting at a given page
 * We assume that the bbt bits are in consecutive order.
*/
static int read_abs_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td, int chip)
{
	struct nand_chip *this = mtd->priv;
	int res = 0, i;

	if (td->options & NAND_BBT_PERCHIP) {
		int offs = 0;
		for (i = 0; i < this->numchips; i++) {
			if (chip == -1 || chip == i)
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				res = read_bbt(mtd, buf, td->pages[i],
					this->chipsize >> this->bbt_erase_shift,
					td, offs);
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			if (res)
				return res;
			offs += this->chipsize >> (this->bbt_erase_shift + 2);
		}
	} else {
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		res = read_bbt(mtd, buf, td->pages[0],
				mtd->size >> this->bbt_erase_shift, td, 0);
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		if (res)
			return res;
	}
	return 0;
}

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/*
 * BBT marker is in the first page, no OOB.
 */
static int scan_read_raw_data(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
			 struct nand_bbt_descr *td)
{
	size_t retlen;
	size_t len;

	len = td->len;
	if (td->options & NAND_BBT_VERSION)
		len++;

	return mtd->read(mtd, offs, len, &retlen, buf);
}

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/*
 * Scan read raw data from flash
 */
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static int scan_read_raw_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
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			 size_t len)
{
	struct mtd_oob_ops ops;
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	int res;
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	ops.mode = MTD_OOB_RAW;
	ops.ooboffs = 0;
	ops.ooblen = mtd->oobsize;

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	while (len > 0) {
		if (len <= mtd->writesize) {
			ops.oobbuf = buf + len;
			ops.datbuf = buf;
			ops.len = len;
			return mtd->read_oob(mtd, offs, &ops);
		} else {
			ops.oobbuf = buf + mtd->writesize;
			ops.datbuf = buf;
			ops.len = mtd->writesize;
			res = mtd->read_oob(mtd, offs, &ops);

			if (res)
				return res;
		}

		buf += mtd->oobsize + mtd->writesize;
		len -= mtd->writesize;
	}
	return 0;
}

static int scan_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
			 size_t len, struct nand_bbt_descr *td)
{
	if (td->options & NAND_BBT_NO_OOB)
		return scan_read_raw_data(mtd, buf, offs, td);
	else
		return scan_read_raw_oob(mtd, buf, offs, len);
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}

/*
 * Scan write data with oob to flash
 */
static int scan_write_bbt(struct mtd_info *mtd, loff_t offs, size_t len,
			  uint8_t *buf, uint8_t *oob)
{
	struct mtd_oob_ops ops;

	ops.mode = MTD_OOB_PLACE;
	ops.ooboffs = 0;
	ops.ooblen = mtd->oobsize;
	ops.datbuf = buf;
	ops.oobbuf = oob;
	ops.len = len;

	return mtd->write_oob(mtd, offs, &ops);
}

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static u32 bbt_get_ver_offs(struct mtd_info *mtd, struct nand_bbt_descr *td)
{
	u32 ver_offs = td->veroffs;

	if (!(td->options & NAND_BBT_NO_OOB))
		ver_offs += mtd->writesize;
	return ver_offs;
}

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/**
 * read_abs_bbts - [GENERIC] Read the bad block table(s) for all chips starting at a given page
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table
 * @md:		descriptor for the bad block table mirror
 *
 * Read the bad block table(s) for all chips starting at a given page
 * We assume that the bbt bits are in consecutive order.
 *
*/
static int read_abs_bbts(struct mtd_info *mtd, uint8_t *buf,
			 struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
	struct nand_chip *this = mtd->priv;

	/* Read the primary version, if available */
	if (td->options & NAND_BBT_VERSION) {
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		scan_read_raw(mtd, buf, (loff_t)td->pages[0] << this->page_shift,
			      mtd->writesize, td);
		td->version[0] = buf[bbt_get_ver_offs(mtd, td)];
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		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
		       td->pages[0], td->version[0]);
	}

	/* Read the mirror version, if available */
	if (md && (md->options & NAND_BBT_VERSION)) {
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		scan_read_raw(mtd, buf, (loff_t)md->pages[0] << this->page_shift,
			      mtd->writesize, td);
		md->version[0] = buf[bbt_get_ver_offs(mtd, md)];
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		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
		       md->pages[0], md->version[0]);
	}
	return 1;
}

/*
 * Scan a given block full
 */
static int scan_block_full(struct mtd_info *mtd, struct nand_bbt_descr *bd,
			   loff_t offs, uint8_t *buf, size_t readlen,
			   int scanlen, int len)
{
	int ret, j;

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	ret = scan_read_raw_oob(mtd, buf, offs, readlen);
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	if (ret)
		return ret;

	for (j = 0; j < len; j++, buf += scanlen) {
		if (check_pattern(buf, scanlen, mtd->writesize, bd))
			return 1;
	}
	return 0;
}

/*
 * Scan a given block partially
 */
static int scan_block_fast(struct mtd_info *mtd, struct nand_bbt_descr *bd,
			   loff_t offs, uint8_t *buf, int len)
{
	struct mtd_oob_ops ops;
	int j, ret;

	ops.ooblen = mtd->oobsize;
	ops.oobbuf = buf;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.mode = MTD_OOB_PLACE;

	for (j = 0; j < len; j++) {
		/*
		 * Read the full oob until read_oob is fixed to
		 * handle single byte reads for 16 bit
		 * buswidth
		 */
		ret = mtd->read_oob(mtd, offs, &ops);
		if (ret)
			return ret;

		if (check_short_pattern(buf, bd))
			return 1;

		offs += mtd->writesize;
	}
	return 0;
}

/**
 * create_bbt - [GENERIC] Create a bad block table by scanning the device
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @bd:		descriptor for the good/bad block search pattern
 * @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 nand_chip *this = mtd->priv;
	int i, numblocks, len, scanlen;
	int startblock;
	loff_t from;
	size_t readlen;

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	MTDDEBUG(MTD_DEBUG_LEVEL0, "Scanning device for bad blocks\n");
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	if (bd->options & NAND_BBT_SCANALLPAGES)
		len = 1 << (this->bbt_erase_shift - this->page_shift);
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	else if (bd->options & NAND_BBT_SCAN2NDPAGE)
		len = 2;
	else
		len = 1;
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	if (!(bd->options & NAND_BBT_SCANEMPTY)) {
		/* We need only read few bytes from the OOB area */
		scanlen = 0;
		readlen = bd->len;
	} else {
		/* Full page content should be read */
		scanlen = mtd->writesize + mtd->oobsize;
		readlen = len * mtd->writesize;
	}

	if (chip == -1) {
		/* Note that numblocks is 2 * (real numblocks) here, see i+=2
		 * below as it makes shifting and masking less painful */
		numblocks = mtd->size >> (this->bbt_erase_shift - 1);
		startblock = 0;
		from = 0;
	} else {
		if (chip >= this->numchips) {
			printk(KERN_WARNING "create_bbt(): chipnr (%d) > available chips (%d)\n",
			       chip + 1, this->numchips);
			return -EINVAL;
		}
		numblocks = this->chipsize >> (this->bbt_erase_shift - 1);
		startblock = chip * numblocks;
		numblocks += startblock;
		from = (loff_t)startblock << (this->bbt_erase_shift - 1);
	}

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	if (this->options & NAND_BBT_SCANLASTPAGE)
		from += mtd->erasesize - (mtd->writesize * len);

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	for (i = startblock; i < numblocks;) {
		int ret;

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		BUG_ON(bd->options & NAND_BBT_NO_OOB);

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		if (bd->options & NAND_BBT_SCANALLPAGES)
			ret = scan_block_full(mtd, bd, from, buf, readlen,
					      scanlen, len);
		else
			ret = scan_block_fast(mtd, bd, from, buf, len);

		if (ret < 0)
			return ret;

		if (ret) {
			this->bbt[i >> 3] |= 0x03 << (i & 0x6);
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			MTDDEBUG(MTD_DEBUG_LEVEL0,
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				  "Bad eraseblock %d at 0x%012llx\n",
				  i >> 1, (unsigned long long)from);
			mtd->ecc_stats.badblocks++;
		}

		i += 2;
		from += (1 << this->bbt_erase_shift);
	}
	return 0;
}

/**
 * search_bbt - [GENERIC] scan the device for a specific bad block table
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table
 *
 * Read the bad block table by searching for a given ident pattern.
 * Search is preformed either from the beginning up or from the end of
 * the device downwards. The search starts always at the start of a
 * block.
 * If the option NAND_BBT_PERCHIP is given, each chip is searched
 * for a bbt, which contains the bad block information of this chip.
 * This is necessary to provide support for certain DOC devices.
 *
 * The bbt ident pattern resides in the oob area of the first page
 * in a block.
 */
static int search_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td)
{
	struct nand_chip *this = mtd->priv;
	int i, chips;
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	int startblock, block, dir;
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	int scanlen = mtd->writesize + mtd->oobsize;
	int bbtblocks;
	int blocktopage = this->bbt_erase_shift - this->page_shift;

	/* Search direction top -> down ? */
	if (td->options & NAND_BBT_LASTBLOCK) {
		startblock = (mtd->size >> this->bbt_erase_shift) - 1;
		dir = -1;
	} else {
		startblock = 0;
		dir = 1;
	}

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chips = this->numchips;
		bbtblocks = this->chipsize >> this->bbt_erase_shift;
		startblock &= bbtblocks - 1;
	} else {
		chips = 1;
		bbtblocks = mtd->size >> this->bbt_erase_shift;
	}

	for (i = 0; i < chips; i++) {
		/* Reset version information */
		td->version[i] = 0;
		td->pages[i] = -1;
		/* Scan the maximum number of blocks */
		for (block = 0; block < td->maxblocks; block++) {

			int actblock = startblock + dir * block;
			loff_t offs = (loff_t)actblock << this->bbt_erase_shift;

			/* Read first page */
637
			scan_read_raw(mtd, buf, offs, mtd->writesize, td);
638 639 640
			if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
				td->pages[i] = actblock << blocktopage;
				if (td->options & NAND_BBT_VERSION) {
641 642
					offs = bbt_get_ver_offs(mtd, td);
					td->version[i] = buf[offs];
643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825
				}
				break;
			}
		}
		startblock += this->chipsize >> this->bbt_erase_shift;
	}
	/* Check, if we found a bbt for each requested chip */
	for (i = 0; i < chips; i++) {
		if (td->pages[i] == -1)
			printk(KERN_WARNING "Bad block table not found for chip %d\n", i);
		else
			printk(KERN_DEBUG "Bad block table found at page %d, version 0x%02X\n", td->pages[i],
			       td->version[i]);
	}
	return 0;
}

/**
 * search_read_bbts - [GENERIC] scan the device for bad block table(s)
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table
 * @md:		descriptor for the bad block table mirror
 *
 * Search and read the bad block table(s)
*/
static int search_read_bbts(struct mtd_info *mtd, uint8_t * buf, struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
	/* Search the primary table */
	search_bbt(mtd, buf, td);

	/* Search the mirror table */
	if (md)
		search_bbt(mtd, buf, md);

	/* Force result check */
	return 1;
}

/**
 * write_bbt - [GENERIC] (Re)write the bad block table
 *
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table
 * @md:		descriptor for the bad block table mirror
 * @chipsel:	selector for a specific chip, -1 for all
 *
 * (Re)write the bad block table
 *
*/
static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
		     struct nand_bbt_descr *td, struct nand_bbt_descr *md,
		     int chipsel)
{
	struct nand_chip *this = mtd->priv;
	struct erase_info einfo;
	int i, j, res, chip = 0;
	int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
	int nrchips, bbtoffs, pageoffs, ooboffs;
	uint8_t msk[4];
	uint8_t rcode = td->reserved_block_code;
	size_t retlen, len = 0;
	loff_t to;
	struct mtd_oob_ops ops;

	ops.ooblen = mtd->oobsize;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.mode = MTD_OOB_PLACE;

	if (!rcode)
		rcode = 0xff;
	/* Write bad block table per chip rather than per device ? */
	if (td->options & NAND_BBT_PERCHIP) {
		numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
		/* Full device write or specific chip ? */
		if (chipsel == -1) {
			nrchips = this->numchips;
		} else {
			nrchips = chipsel + 1;
			chip = chipsel;
		}
	} else {
		numblocks = (int)(mtd->size >> this->bbt_erase_shift);
		nrchips = 1;
	}

	/* Loop through the chips */
	for (; chip < nrchips; chip++) {

		/* There was already a version of the table, reuse the page
		 * This applies for absolute placement too, as we have the
		 * page nr. in td->pages.
		 */
		if (td->pages[chip] != -1) {
			page = td->pages[chip];
			goto write;
		}

		/* Automatic placement of the bad block table */
		/* Search direction top -> down ? */
		if (td->options & NAND_BBT_LASTBLOCK) {
			startblock = numblocks * (chip + 1) - 1;
			dir = -1;
		} else {
			startblock = chip * numblocks;
			dir = 1;
		}

		for (i = 0; i < td->maxblocks; i++) {
			int block = startblock + dir * i;
			/* Check, if the block is bad */
			switch ((this->bbt[block >> 2] >>
				 (2 * (block & 0x03))) & 0x03) {
			case 0x01:
			case 0x03:
				continue;
			}
			page = block <<
				(this->bbt_erase_shift - this->page_shift);
			/* Check, if the block is used by the mirror table */
			if (!md || md->pages[chip] != page)
				goto write;
		}
		printk(KERN_ERR "No space left to write bad block table\n");
		return -ENOSPC;
	write:

		/* Set up shift count and masks for the flash table */
		bits = td->options & NAND_BBT_NRBITS_MSK;
		msk[2] = ~rcode;
		switch (bits) {
		case 1: sft = 3; sftmsk = 0x07; msk[0] = 0x00; msk[1] = 0x01;
			msk[3] = 0x01;
			break;
		case 2: sft = 2; sftmsk = 0x06; msk[0] = 0x00; msk[1] = 0x01;
			msk[3] = 0x03;
			break;
		case 4: sft = 1; sftmsk = 0x04; msk[0] = 0x00; msk[1] = 0x0C;
			msk[3] = 0x0f;
			break;
		case 8: sft = 0; sftmsk = 0x00; msk[0] = 0x00; msk[1] = 0x0F;
			msk[3] = 0xff;
			break;
		default: return -EINVAL;
		}

		bbtoffs = chip * (numblocks >> 2);

		to = ((loff_t) page) << this->page_shift;

		/* Must we save the block contents ? */
		if (td->options & NAND_BBT_SAVECONTENT) {
			/* Make it block aligned */
			to &= ~((loff_t) ((1 << this->bbt_erase_shift) - 1));
			len = 1 << this->bbt_erase_shift;
			res = mtd->read(mtd, to, len, &retlen, buf);
			if (res < 0) {
				if (retlen != len) {
					printk(KERN_INFO "nand_bbt: Error "
					       "reading block for writing "
					       "the bad block table\n");
					return res;
				}
				printk(KERN_WARNING "nand_bbt: ECC error "
				       "while reading block for writing "
				       "bad block table\n");
			}
			/* Read oob data */
			ops.ooblen = (len >> this->page_shift) * mtd->oobsize;
			ops.oobbuf = &buf[len];
			res = mtd->read_oob(mtd, to + mtd->writesize, &ops);
			if (res < 0 || ops.oobretlen != ops.ooblen)
				goto outerr;

			/* Calc the byte offset in the buffer */
			pageoffs = page - (int)(to >> this->page_shift);
			offs = pageoffs << this->page_shift;
			/* Preset the bbt area with 0xff */
			memset(&buf[offs], 0xff, (size_t) (numblocks >> sft));
			ooboffs = len + (pageoffs * mtd->oobsize);

826 827 828 829 830 831 832 833 834 835 836 837 838 839 840
		} else if (td->options & NAND_BBT_NO_OOB) {
			ooboffs = 0;
			offs = td->len;
			/* the version byte */
			if (td->options & NAND_BBT_VERSION)
				offs++;
			/* Calc length */
			len = (size_t) (numblocks >> sft);
			len += offs;
			/* Make it page aligned ! */
			len = ALIGN(len, mtd->writesize);
			/* Preset the buffer with 0xff */
			memset(buf, 0xff, len);
			/* Pattern is located at the begin of first page */
			memcpy(buf, td->pattern, td->len);
841 842 843 844
		} else {
			/* Calc length */
			len = (size_t) (numblocks >> sft);
			/* Make it page aligned ! */
845
			len = ALIGN(len, mtd->writesize);
846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878
			/* Preset the buffer with 0xff */
			memset(buf, 0xff, len +
			       (len >> this->page_shift)* mtd->oobsize);
			offs = 0;
			ooboffs = len;
			/* Pattern is located in oob area of first page */
			memcpy(&buf[ooboffs + td->offs], td->pattern, td->len);
		}

		if (td->options & NAND_BBT_VERSION)
			buf[ooboffs + td->veroffs] = td->version[chip];

		/* walk through the memory table */
		for (i = 0; i < numblocks;) {
			uint8_t dat;
			dat = this->bbt[bbtoffs + (i >> 2)];
			for (j = 0; j < 4; j++, i++) {
				int sftcnt = (i << (3 - sft)) & sftmsk;
				/* Do not store the reserved bbt blocks ! */
				buf[offs + (i >> sft)] &=
					~(msk[dat & 0x03] << sftcnt);
				dat >>= 2;
			}
		}

		memset(&einfo, 0, sizeof(einfo));
		einfo.mtd = mtd;
		einfo.addr = to;
		einfo.len = 1 << this->bbt_erase_shift;
		res = nand_erase_nand(mtd, &einfo, 1);
		if (res < 0)
			goto outerr;

879 880 881
		res = scan_write_bbt(mtd, to, len, buf,
				td->options & NAND_BBT_NO_OOB ? NULL :
				&buf[len]);
882 883 884
		if (res < 0)
			goto outerr;

885 886
		printk(KERN_DEBUG "Bad block table written to 0x%012llx, version "
		       "0x%02X\n", (unsigned long long)to, td->version[chip]);
887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946

		/* Mark it as used */
		td->pages[chip] = page;
	}
	return 0;

 outerr:
	printk(KERN_WARNING
	       "nand_bbt: Error while writing bad block table %d\n", res);
	return res;
}

/**
 * nand_memory_bbt - [GENERIC] create a memory based bad block table
 * @mtd:	MTD device structure
 * @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 nand_memory_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
	struct nand_chip *this = mtd->priv;

	bd->options &= ~NAND_BBT_SCANEMPTY;
	return create_bbt(mtd, this->buffers->databuf, bd, -1);
}

/**
 * check_create - [GENERIC] create and write bbt(s) if necessary
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @bd:		descriptor for the good/bad block search pattern
 *
 * The function checks the results of the previous call to read_bbt
 * and creates / updates the bbt(s) if necessary
 * Creation is necessary if no bbt was found for the chip/device
 * Update is necessary if one of the tables is missing or the
 * version nr. of one table is less than the other
*/
static int check_create(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd)
{
	int i, chips, writeops, chipsel, res;
	struct nand_chip *this = mtd->priv;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;
	struct nand_bbt_descr *rd, *rd2;

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP)
		chips = this->numchips;
	else
		chips = 1;

	for (i = 0; i < chips; i++) {
		writeops = 0;
		rd = NULL;
		rd2 = NULL;
		/* Per chip or per device ? */
		chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
947
		/* Mirrored table available ? */
948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
		if (md) {
			if (td->pages[i] == -1 && md->pages[i] == -1) {
				writeops = 0x03;
				goto create;
			}

			if (td->pages[i] == -1) {
				rd = md;
				td->version[i] = md->version[i];
				writeops = 1;
				goto writecheck;
			}

			if (md->pages[i] == -1) {
				rd = td;
				md->version[i] = td->version[i];
				writeops = 2;
				goto writecheck;
			}

			if (td->version[i] == md->version[i]) {
				rd = td;
				if (!(td->options & NAND_BBT_VERSION))
					rd2 = md;
				goto writecheck;
			}

			if (((int8_t) (td->version[i] - md->version[i])) > 0) {
				rd = td;
				md->version[i] = td->version[i];
				writeops = 2;
			} else {
				rd = md;
				td->version[i] = md->version[i];
				writeops = 1;
			}

			goto writecheck;

		} else {
			if (td->pages[i] == -1) {
				writeops = 0x01;
				goto create;
			}
			rd = td;
			goto writecheck;
		}
	create:
		/* Create the bad block table by scanning the device ? */
		if (!(td->options & NAND_BBT_CREATE))
			continue;

		/* Create the table in memory by scanning the chip(s) */
1001 1002
		if (!(this->options & NAND_CREATE_EMPTY_BBT))
			create_bbt(mtd, buf, bd, chipsel);
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066

		td->version[i] = 1;
		if (md)
			md->version[i] = 1;
	writecheck:
		/* read back first ? */
		if (rd)
			read_abs_bbt(mtd, buf, rd, chipsel);
		/* If they weren't versioned, read both. */
		if (rd2)
			read_abs_bbt(mtd, buf, rd2, chipsel);

		/* Write the bad block table to the device ? */
		if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
			res = write_bbt(mtd, buf, td, md, chipsel);
			if (res < 0)
				return res;
		}

		/* Write the mirror bad block table to the device ? */
		if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
			res = write_bbt(mtd, buf, md, td, chipsel);
			if (res < 0)
				return res;
		}
	}
	return 0;
}

/**
 * mark_bbt_regions - [GENERIC] mark the bad block table regions
 * @mtd:	MTD device structure
 * @td:		bad block table descriptor
 *
 * The bad block table regions are marked as "bad" to prevent
 * accidental erasures / writes. The regions are identified by
 * the mark 0x02.
*/
static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
{
	struct nand_chip *this = mtd->priv;
	int i, j, chips, block, nrblocks, update;
	uint8_t oldval, newval;

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chips = this->numchips;
		nrblocks = (int)(this->chipsize >> this->bbt_erase_shift);
	} else {
		chips = 1;
		nrblocks = (int)(mtd->size >> this->bbt_erase_shift);
	}

	for (i = 0; i < chips; i++) {
		if ((td->options & NAND_BBT_ABSPAGE) ||
		    !(td->options & NAND_BBT_WRITE)) {
			if (td->pages[i] == -1)
				continue;
			block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
			block <<= 1;
			oldval = this->bbt[(block >> 3)];
			newval = oldval | (0x2 << (block & 0x06));
			this->bbt[(block >> 3)] = newval;
			if ((oldval != newval) && td->reserved_block_code)
1067
				nand_update_bbt(mtd, (loff_t)block << (this->bbt_erase_shift - 1));
1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
			continue;
		}
		update = 0;
		if (td->options & NAND_BBT_LASTBLOCK)
			block = ((i + 1) * nrblocks) - td->maxblocks;
		else
			block = i * nrblocks;
		block <<= 1;
		for (j = 0; j < td->maxblocks; j++) {
			oldval = this->bbt[(block >> 3)];
			newval = oldval | (0x2 << (block & 0x06));
			this->bbt[(block >> 3)] = newval;
			if (oldval != newval)
				update = 1;
			block += 2;
		}
		/* If we want reserved blocks to be recorded to flash, and some
		   new ones have been marked, then we need to update the stored
		   bbts.  This should only happen once. */
		if (update && td->reserved_block_code)
1088
			nand_update_bbt(mtd, (loff_t)(block - 2) << (this->bbt_erase_shift - 1));
1089 1090 1091
	}
}

1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139
/**
 * verify_bbt_descr - verify the bad block description
 * @mtd:	MTD device structure
 * @bd:		the table to verify
 *
 * This functions performs a few sanity checks on the bad block description
 * table.
 */
static void verify_bbt_descr(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
	struct nand_chip *this = mtd->priv;
	u32 pattern_len;
	u32 bits;
	u32 table_size;

	if (!bd)
		return;

	pattern_len = bd->len;
	bits = bd->options & NAND_BBT_NRBITS_MSK;

	BUG_ON((this->options & NAND_USE_FLASH_BBT_NO_OOB) &&
			!(this->options & NAND_USE_FLASH_BBT));
	BUG_ON(!bits);

	if (bd->options & NAND_BBT_VERSION)
		pattern_len++;

	if (bd->options & NAND_BBT_NO_OOB) {
		BUG_ON(!(this->options & NAND_USE_FLASH_BBT));
		BUG_ON(!(this->options & NAND_USE_FLASH_BBT_NO_OOB));
		BUG_ON(bd->offs);
		if (bd->options & NAND_BBT_VERSION)
			BUG_ON(bd->veroffs != bd->len);
		BUG_ON(bd->options & NAND_BBT_SAVECONTENT);
	}

	if (bd->options & NAND_BBT_PERCHIP)
		table_size = this->chipsize >> this->bbt_erase_shift;
	else
		table_size = mtd->size >> this->bbt_erase_shift;
	table_size >>= 3;
	table_size *= bits;
	if (bd->options & NAND_BBT_NO_OOB)
		table_size += pattern_len;
	BUG_ON(table_size > (1 << this->bbt_erase_shift));
}

1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180
/**
 * nand_scan_bbt - [NAND Interface] scan, find, read and maybe create bad block table(s)
 * @mtd:	MTD device structure
 * @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 nand_free_bbt function.
 *
*/
int nand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
	struct nand_chip *this = mtd->priv;
	int len, res = 0;
	uint8_t *buf;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;

	len = mtd->size >> (this->bbt_erase_shift + 2);
	/* Allocate memory (2bit per block) and clear the memory bad block table */
	this->bbt = kzalloc(len, GFP_KERNEL);
	if (!this->bbt) {
		printk(KERN_ERR "nand_scan_bbt: Out of memory\n");
		return -ENOMEM;
	}

	/* If no primary table decriptor is given, scan the device
	 * to build a memory based bad block table
	 */
	if (!td) {
		if ((res = nand_memory_bbt(mtd, bd))) {
			printk(KERN_ERR "nand_bbt: Can't scan flash and build the RAM-based BBT\n");
			kfree(this->bbt);
			this->bbt = NULL;
		}
		return res;
	}
1181 1182
	verify_bbt_descr(mtd, td);
	verify_bbt_descr(mtd, md);
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311

	/* Allocate a temporary buffer for one eraseblock incl. oob */
	len = (1 << this->bbt_erase_shift);
	len += (len >> this->page_shift) * mtd->oobsize;
	buf = vmalloc(len);
	if (!buf) {
		printk(KERN_ERR "nand_bbt: Out of memory\n");
		kfree(this->bbt);
		this->bbt = NULL;
		return -ENOMEM;
	}

	/* Is the bbt at a given page ? */
	if (td->options & NAND_BBT_ABSPAGE) {
		res = read_abs_bbts(mtd, buf, td, md);
	} else {
		/* Search the bad block table using a pattern in oob */
		res = search_read_bbts(mtd, buf, td, md);
	}

	if (res)
		res = check_create(mtd, buf, bd);

	/* Prevent the bbt regions from erasing / writing */
	mark_bbt_region(mtd, td);
	if (md)
		mark_bbt_region(mtd, md);

	vfree(buf);
	return res;
}

/**
 * nand_update_bbt - [NAND Interface] update bad block table(s)
 * @mtd:	MTD device structure
 * @offs:	the offset of the newly marked block
 *
 * The function updates the bad block table(s)
*/
int nand_update_bbt(struct mtd_info *mtd, loff_t offs)
{
	struct nand_chip *this = mtd->priv;
	int len, res = 0, writeops = 0;
	int chip, chipsel;
	uint8_t *buf;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;

	if (!this->bbt || !td)
		return -EINVAL;

	/* Allocate a temporary buffer for one eraseblock incl. oob */
	len = (1 << this->bbt_erase_shift);
	len += (len >> this->page_shift) * mtd->oobsize;
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf) {
		printk(KERN_ERR "nand_update_bbt: Out of memory\n");
		return -ENOMEM;
	}

	writeops = md != NULL ? 0x03 : 0x01;

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chip = (int)(offs >> this->chip_shift);
		chipsel = chip;
	} else {
		chip = 0;
		chipsel = -1;
	}

	td->version[chip]++;
	if (md)
		md->version[chip]++;

	/* Write the bad block table to the device ? */
	if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
		res = write_bbt(mtd, buf, td, md, chipsel);
		if (res < 0)
			goto out;
	}
	/* Write the mirror bad block table to the device ? */
	if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
		res = write_bbt(mtd, buf, md, td, chipsel);
	}

 out:
	kfree(buf);
	return res;
}

/* 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 uint8_t scan_agand_pattern[] = { 0x1C, 0x71, 0xC7, 0x1C, 0x71, 0xC7 };

static struct nand_bbt_descr agand_flashbased = {
	.options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
	.offs = 0x20,
	.len = 6,
	.pattern = scan_agand_pattern
};

/* Generic flash bbt decriptors
*/
static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };

static struct nand_bbt_descr bbt_main_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs =	8,
	.len = 4,
	.veroffs = 12,
	.maxblocks = 4,
	.pattern = bbt_pattern
};

static struct nand_bbt_descr bbt_mirror_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs =	8,
	.len = 4,
	.veroffs = 12,
	.maxblocks = 4,
	.pattern = mirror_pattern
};

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static struct nand_bbt_descr bbt_main_no_bbt_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
		| NAND_BBT_NO_OOB,
	.len = 4,
	.veroffs = 4,
	.maxblocks = 4,
	.pattern = bbt_pattern
};

static struct nand_bbt_descr bbt_mirror_no_bbt_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
		| NAND_BBT_NO_OOB,
	.len = 4,
	.veroffs = 4,
	.maxblocks = 4,
	.pattern = mirror_pattern
};

#define BBT_SCAN_OPTIONS (NAND_BBT_SCANLASTPAGE | NAND_BBT_SCAN2NDPAGE | \
		NAND_BBT_SCANBYTE1AND6)
/**
 * nand_create_default_bbt_descr - [Internal] Creates a BBT descriptor structure
 * @this:	NAND chip to create descriptor for
 *
 * This function allocates and initializes a nand_bbt_descr for BBM detection
 * based on the properties of "this". The new descriptor is stored in
 * this->badblock_pattern. Thus, this->badblock_pattern should be NULL when
 * passed to this function.
 *
 */
static int nand_create_default_bbt_descr(struct nand_chip *this)
{
	struct nand_bbt_descr *bd;
	if (this->badblock_pattern) {
		printk(KERN_WARNING "BBT descr already allocated; not replacing.\n");
		return -EINVAL;
	}
	bd = kzalloc(sizeof(*bd), GFP_KERNEL);
	if (!bd) {
		printk(KERN_ERR "nand_create_default_bbt_descr: Out of memory\n");
		return -ENOMEM;
	}
	bd->options = this->options & BBT_SCAN_OPTIONS;
	bd->offs = this->badblockpos;
	bd->len = (this->options & NAND_BUSWIDTH_16) ? 2 : 1;
	bd->pattern = scan_ff_pattern;
	bd->options |= NAND_BBT_DYNAMICSTRUCT;
	this->badblock_pattern = bd;
	return 0;
}

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/**
 * nand_default_bbt - [NAND Interface] Select a default bad block table for the device
 * @mtd:	MTD device structure
 *
 * This function selects the default bad block table
 * support for the device and calls the nand_scan_bbt function
 *
*/
int nand_default_bbt(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd->priv;

	/* Default for AG-AND. We must use a flash based
	 * bad block table as the devices have factory marked
	 * _good_ blocks. Erasing those blocks leads to loss
	 * of the good / bad information, so we _must_ store
	 * this information in a good / bad table during
	 * startup
	 */
	if (this->options & NAND_IS_AND) {
		/* Use the default pattern descriptors */
		if (!this->bbt_td) {
			this->bbt_td = &bbt_main_descr;
			this->bbt_md = &bbt_mirror_descr;
		}
		this->options |= NAND_USE_FLASH_BBT;
		return nand_scan_bbt(mtd, &agand_flashbased);
	}

	/* Is a flash based bad block table requested ? */
	if (this->options & NAND_USE_FLASH_BBT) {
		/* Use the default pattern descriptors */
		if (!this->bbt_td) {
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			if (this->options & NAND_USE_FLASH_BBT_NO_OOB) {
				this->bbt_td = &bbt_main_no_bbt_descr;
				this->bbt_md = &bbt_mirror_no_bbt_descr;
			} else {
				this->bbt_td = &bbt_main_descr;
				this->bbt_md = &bbt_mirror_descr;
			}
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		}
	} else {
		this->bbt_td = NULL;
		this->bbt_md = NULL;
	}
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	if (!this->badblock_pattern)
		nand_create_default_bbt_descr(this);

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	return nand_scan_bbt(mtd, this->badblock_pattern);
}

/**
 * nand_isbad_bbt - [NAND Interface] Check if a block is bad
 * @mtd:	MTD device structure
 * @offs:	offset in the device
 * @allowbbt:	allow access to bad block table region
 *
*/
int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
	struct nand_chip *this = mtd->priv;
	int block;
	uint8_t res;

	/* Get block number * 2 */
	block = (int)(offs >> (this->bbt_erase_shift - 1));
	res = (this->bbt[block >> 3] >> (block & 0x06)) & 0x03;

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	MTDDEBUG(MTD_DEBUG_LEVEL2, "nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
	      (unsigned int)offs, block >> 1, res);
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	switch ((int)res) {
	case 0x00:
		return 0;
	case 0x01:
		return 1;
	case 0x02:
		return allowbbt ? 0 : 1;
	}
	return 1;
}