linux nand flash 驱动简单介绍

linux中为nand flash驱动提供了很多操作接口,开发只需要填充相应的接口即可。


nand flash只需要完成读页、写页、读oob、写oob、擦除页,这几个接口完成了,基本的操作也就完了,基本上就完成了大部分操作。最后,基于这些操作,完成ecc(软件或者硬件,现在大多数nand flash都是硬件ecc了,方便多了),坏块标记位置的正确读写,这个就可以正常的标记坏块和扫描坏块了。


几个与nand相关的核心层代码:

drivers/mtd/nand/nand_ids.c

这个里面很简单,就两个结构体赋值

/*
*	Manufacturer ID list
*/
struct nand_manufacturers nand_manuf_ids[] = {
	{NAND_MFR_TOSHIBA, "Toshiba"},
	{NAND_MFR_SAMSUNG, "Samsung"},
	{NAND_MFR_FUJITSU, "Fujitsu"},
	{NAND_MFR_NATIONAL, "National"},
	{NAND_MFR_RENESAS, "Renesas"},
	{NAND_MFR_STMICRO, "ST Micro"},
	{NAND_MFR_HYNIX, "Hynix"},
	{NAND_MFR_MICRON, "Micron"},
	{NAND_MFR_AMD, "AMD"},
	{0x0, "Unknown"}
};
为芯片添加厂家ID和厂家名称,ID是芯片手册上的,名称随便填,规范点还是填厂家名字

/*
*	Chip ID list
*
*	Name. ID code, pagesize, chipsize in MegaByte, eraseblock size,
*	options
*
*	Pagesize; 0, 256, 512
*	0	get this information from the extended chip ID
+	256	256 Byte page size
*	512	512 Byte page size
*/
struct nand_flash_dev nand_flash_ids[] = {

#ifdef CONFIG_MTD_NAND_MUSEUM_IDS
	{"NAND 1MiB 5V 8-bit",		0x6e, 256, 1, 0x1000, 0},
	{"NAND 2MiB 5V 8-bit",		0x64, 256, 2, 0x1000, 0},
	{"NAND 4MiB 5V 8-bit",		0x6b, 512, 4, 0x2000, 0},
	{"NAND 1MiB 3,3V 8-bit",	0xe8, 256, 1, 0x1000, 0},
	{"NAND 1MiB 3,3V 8-bit",	0xec, 256, 1, 0x1000, 0},
	{"NAND 2MiB 3,3V 8-bit",	0xea, 256, 2, 0x1000, 0},
	{"NAND 4MiB 3,3V 8-bit",	0xd5, 512, 4, 0x2000, 0},
	{"NAND 4MiB 3,3V 8-bit",	0xe3, 512, 4, 0x2000, 0},
	{"NAND 4MiB 3,3V 8-bit",	0xe5, 512, 4, 0x2000, 0},
	{"NAND 8MiB 3,3V 8-bit",	0xd6, 512, 8, 0x2000, 0},

	{"NAND 8MiB 1,8V 8-bit",	0x39, 512, 8, 0x2000, 0},
	{"NAND 8MiB 3,3V 8-bit",	0xe6, 512, 8, 0x2000, 0},
	{"NAND 8MiB 1,8V 16-bit",	0x49, 512, 8, 0x2000, NAND_BUSWIDTH_16},
	{"NAND 8MiB 3,3V 16-bit",	0x59, 512, 8, 0x2000, NAND_BUSWIDTH_16},
#endif

	{"NAND 16MiB 1,8V 8-bit",	0x33, 512, 16, 0x4000, 0},
	{"NAND 16MiB 3,3V 8-bit",	0x73, 512, 16, 0x4000, 0},
	{"NAND 16MiB 1,8V 16-bit",	0x43, 512, 16, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 16MiB 3,3V 16-bit",	0x53, 512, 16, 0x4000, NAND_BUSWIDTH_16},

	{"NAND 32MiB 1,8V 8-bit",	0x35, 512, 32, 0x4000, 0},
	{"NAND 32MiB 3,3V 8-bit",	0x75, 512, 32, 0x4000, 0},
	{"NAND 32MiB 1,8V 16-bit",	0x45, 512, 32, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 32MiB 3,3V 16-bit",	0x55, 512, 32, 0x4000, NAND_BUSWIDTH_16},

	{"NAND 64MiB 1,8V 8-bit",	0x36, 512, 64, 0x4000, 0},
	{"NAND 64MiB 3,3V 8-bit",	0x76, 512, 64, 0x4000, 0},
	{"NAND 64MiB 1,8V 16-bit",	0x46, 512, 64, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 64MiB 3,3V 16-bit",	0x56, 512, 64, 0x4000, NAND_BUSWIDTH_16},

	{"NAND 128MiB 1,8V 8-bit",	0x78, 512, 128, 0x4000, 0},
	{"NAND 128MiB 1,8V 8-bit",	0x39, 512, 128, 0x4000, 0},
	{"NAND 128MiB 3,3V 8-bit",	0x79, 512, 128, 0x4000, 0},
	{"NAND 128MiB 1,8V 16-bit",	0x72, 512, 128, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 128MiB 1,8V 16-bit",	0x49, 512, 128, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 128MiB 3,3V 16-bit",	0x74, 512, 128, 0x4000, NAND_BUSWIDTH_16},
	{"NAND 128MiB 3,3V 16-bit",	0x59, 512, 128, 0x4000, NAND_BUSWIDTH_16},

	{"NAND 256MiB 3,3V 8-bit",	0x71, 512, 256, 0x4000, 0},

	/*
	 * These are the new chips with large page size. The pagesize and the
	 * erasesize is determined from the extended id bytes
	 */
#define LP_OPTIONS (NAND_SAMSUNG_LP_OPTIONS | NAND_NO_READRDY | NAND_NO_AUTOINCR)
#define LP_OPTIONS16 (LP_OPTIONS | NAND_BUSWIDTH_16)

	/*512 Megabit */
	{"NAND 64MiB 1,8V 8-bit",	0xA2, 0,  64, 0, LP_OPTIONS},
	{"NAND 64MiB 3,3V 8-bit",	0xF2, 0,  64, 0, LP_OPTIONS},
	{"NAND 64MiB 1,8V 16-bit",	0xB2, 0,  64, 0, LP_OPTIONS16},
	{"NAND 64MiB 3,3V 16-bit",	0xC2, 0,  64, 0, LP_OPTIONS16},

	/* 1 Gigabit */
	{"NAND 128MiB 1,8V 8-bit",	0xA1, 0, 128, 0, LP_OPTIONS},
	{"NAND 128MiB 3,3V 8-bit",	0xF1, 0, 128, 0, LP_OPTIONS},
	{"NAND 128MiB 1,8V 16-bit",	0xB1, 0, 128, 0, LP_OPTIONS16},
	{"NAND 128MiB 3,3V 16-bit",	0xC1, 0, 128, 0, LP_OPTIONS16},

	/* 2 Gigabit */
	{"NAND 256MiB 1,8V 8-bit",	0xAA, 0, 256, 0, LP_OPTIONS},
	{"NAND 256MiB 3,3V 8-bit",	0xDA, 0, 256, 0, LP_OPTIONS},
	{"NAND 256MiB 1,8V 16-bit",	0xBA, 0, 256, 0, LP_OPTIONS16},
	{"NAND 256MiB 3,3V 16-bit",	0xCA, 0, 256, 0, LP_OPTIONS16},

	/* 4 Gigabit */
	{"NAND 512MiB 1,8V 8-bit",	0xAC, 0, 512, 0, LP_OPTIONS},
	{"NAND 512MiB 3,3V 8-bit",	0xDC, 0, 512, 0, LP_OPTIONS},
	{"NAND 512MiB 1,8V 16-bit",	0xBC, 0, 512, 0, LP_OPTIONS16},
	{"NAND 512MiB 3,3V 16-bit",	0xCC, 0, 512, 0, LP_OPTIONS16},


	/* 8 Gigabit */
	{"NAND 1GiB 1,8V 8-bit",	0xA3, 0, 1024, 0, LP_OPTIONS},
	{"NAND 1GiB 3,3V 8-bit",	0xD3, 0, 1024, 0, LP_OPTIONS},
	{"NAND 1GiB 1,8V 16-bit",	0xB3, 0, 1024, 0, LP_OPTIONS16},
	{"NAND 1GiB 3,3V 16-bit",	0xC3, 0, 1024, 0, LP_OPTIONS16},

	/* 16 Gigabit */
	{"NAND 2GiB 1,8V 8-bit",	0xA5, 0, 2048, 0, LP_OPTIONS},
	{"NAND 2GiB 3,3V 8-bit",	0xD5, 0, 2048, 0, LP_OPTIONS},
	{"NAND 2GiB 1,8V 16-bit",	0xB5, 0, 2048, 0, LP_OPTIONS16},
	{"NAND 2GiB 3,3V 16-bit",	0xC5, 0, 2048, 0, LP_OPTIONS16},

	/*
	 * Renesas AND 1 Gigabit. Those chips do not support extended id and
	 * have a strange page/block layout !  The chosen minimum erasesize is
	 * 4 * 2 * 2048 = 16384 Byte, as those chips have an array of 4 page
	 * planes 1 block = 2 pages, but due to plane arrangement the blocks
	 * 0-3 consists of page 0 + 4,1 + 5, 2 + 6, 3 + 7 Anyway JFFS2 would
	 * increase the eraseblock size so we chose a combined one which can be
	 * erased in one go There are more speed improvements for reads and
	 * writes possible, but not implemented now
	 */
	{"AND 128MiB 3,3V 8-bit",	0x01, 2048, 128, 0x4000,
	 NAND_IS_AND | NAND_NO_AUTOINCR |NAND_NO_READRDY | NAND_4PAGE_ARRAY |
	 BBT_AUTO_REFRESH
	},

	{NULL,}
};
/**
 * struct nand_flash_dev - NAND Flash Device ID Structure
 * @name:	Identify the device type
 * @id:		device ID code
 * @pagesize:	Pagesize in bytes. Either 256 or 512 or 0
 *		If the pagesize is 0, then the real pagesize
 *		and the eraseize are determined from the
 *		extended id bytes in the chip
 * @erasesize:	Size of an erase block in the flash device.
 * @chipsize:	Total chipsize in Mega Bytes
 * @options:	Bitfield to store chip relevant options
 */
struct nand_flash_dev {
	char *name;
	int id;
	unsigned long pagesize;
	unsigned long chipsize;
	unsigned long erasesize;
	unsigned long options;
};

这个结构体是给设备赋值,名字,id为设备id,不是厂家id,pagesize在新的nand中都是为0,表示设备信息从芯片id的第三个和第四个中获取,叫extid,第一个为厂家id,第二个为设备id。chipsize为芯片容量,单位为MB,比如上面的128,表示的是128M,1Gbits。erasesize在新的nand中也为0,同理从芯片中读取出来。最后一个是选项,即代表芯片的特性。


drivers/mtd/nand/nand_bbt.c

这个函数主要负责扫描坏块,坏块表建立,标记坏块。

/*
 *  drivers/mtd/nand_bbt.c
 *
 *  Overview:
 *   Bad block table support for the NAND driver
 *
 *  Copyright (C) 2004 Thomas Gleixner ([email protected])
 *
 * 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
 * depending on the options in the bbt descriptor(s). 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.
 * If the tables are not versioned, then we "or" the bad block information.
 * If one of the bbt's 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
 * good / bad blocks and the bad block tables are created.
 *
 * For manufacturer created bbts like the one found on M-SYS DOC devices
 * the bbt is searched and read but never created
 *
 * The autogenerated bad block table is located in the last good blocks
 * of the device. The table is mirrored, so it can be updated eventually.
 * 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.
 *
 * The table uses 2 bits per block
 * 11b: 	block is good
 * 00b: 	block is factory marked bad
 * 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 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

/**
 * 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;

	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;
	}

	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;
	}
	return 0;
}

/**
 * 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
 * @bits:	number of bits per block
 * @offs:	offset in the memory table
 * @reserved_block_code:	Pattern to identify reserved blocks
 *
 * Read the bad block table starting from page.
 *
 */
static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
		    int bits, int offs, int reserved_block_code)
{
	int res, i, j, act = 0;
	struct nand_chip *this = mtd->priv;
	size_t retlen, len, totlen;
	loff_t from;
	uint8_t msk = (uint8_t) ((1 << bits) - 1);

	totlen = (num * bits) >> 3;
	from = ((loff_t) page) << this->page_shift;

	while (totlen) {
		len = min(totlen, (size_t) (1 << this->bbt_erase_shift));
		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",
					       (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
					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",
				       (loff_t)((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
				/* 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;
	int bits;

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

/*
 * Scan read raw data from flash
 */
static int scan_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
			 size_t len)
{
	struct mtd_oob_ops ops;

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

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

/*
 * 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);
}

/**
 * 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) {
		scan_read_raw(mtd, buf, (loff_t)td->pages[0] << this->page_shift,
			      mtd->writesize);
		td->version[0] = buf[mtd->writesize + td->veroffs];
		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)) {
		scan_read_raw(mtd, buf, (loff_t)md->pages[0] << this->page_shift,
			      mtd->writesize);
		md->version[0] = buf[mtd->writesize + md->veroffs];
		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;

	ret = scan_read_raw(mtd, buf, offs, readlen);
	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;

	printk(KERN_INFO "Scanning device for bad blocks\n");

	if (bd->options & NAND_BBT_SCANALLPAGES)
		len = 1 << (this->bbt_erase_shift - this->page_shift);
	else {
		if (bd->options & NAND_BBT_SCAN2NDPAGE)
			len = 2;
		else
			len = 1;
	}

	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);
	}

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

		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);
			printk(KERN_WARNING "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;
	int bits, startblock, block, dir;
	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;
	}

	/* Number of bits for each erase block in the bbt */
	bits = td->options & NAND_BBT_NRBITS_MSK;

	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 */
			scan_read_raw(mtd, buf, offs, mtd->writesize);
			if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
				td->pages[i] = actblock << blocktopage;
				if (td->options & NAND_BBT_VERSION) {
					td->version[i] = buf[mtd->writesize + td->veroffs];
				}
				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);

		} else {
			/* Calc length */
			len = (size_t) (numblocks >> sft);
			/* Make it page aligned ! */
			len = (len + (mtd->writesize - 1)) &
				~(mtd->writesize - 1);
			/* 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;

		res = scan_write_bbt(mtd, to, len, buf, &buf[len]);
		if (res < 0)
			goto outerr;

		printk(KERN_DEBUG "Bad block table written to 0x%012llx, version "
		       "0x%02X\n", (unsigned long long)to, td->version[chip]);

		/* 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;
		/* Mirrored table avilable ? */
		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) */
		create_bbt(mtd, buf, bd, chipsel);

		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)
				nand_update_bbt(mtd, (loff_t)block << (this->bbt_erase_shift - 1));
			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)
			nand_update_bbt(mtd, (loff_t)(block - 2) << (this->bbt_erase_shift - 1));
	}
}

/**
 * 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;
	}

	/* 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 struct nand_bbt_descr smallpage_memorybased = {
	.options = NAND_BBT_SCAN2NDPAGE,
	.offs = 5,
	.len = 1,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr largepage_memorybased = {
	.options = 0,
	.offs = 0,
	.len = 2,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr smallpage_flashbased = {
	.options = NAND_BBT_SCAN2NDPAGE,
	.offs = 5,
	.len = 1,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr largepage_flashbased = {
	.options = NAND_BBT_SCAN2NDPAGE,
	.offs = 0,
	.len = 2,
	.pattern = scan_ff_pattern
};

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
};

/**
 * 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) {
			this->bbt_td = &bbt_main_descr;
			this->bbt_md = &bbt_mirror_descr;
		}
		if (!this->badblock_pattern) {
			this->badblock_pattern = (mtd->writesize > 512) ? &largepage_flashbased : &smallpage_flashbased;
		}
	} else {
		this->bbt_td = NULL;
		this->bbt_md = NULL;
		if (!this->badblock_pattern) {
			this->badblock_pattern = (mtd->writesize > 512) ?
			    &largepage_memorybased : &smallpage_memorybased;
		}
	}
	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;

	DEBUG(MTD_DEBUG_LEVEL2, "nand_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;
}

EXPORT_SYMBOL(nand_scan_bbt);
EXPORT_SYMBOL(nand_default_bbt);

drivers/mtd/nand/nand_ecc.c

nand flash计算ecc相关的 函数,选择不同的ecc校验方式,调用这个文件中不同的函数。这里面有一些默认的校验ecc的方式,如果没有自己实现的话,就会调用这个里面的校验方式。

/*
 * This file contains an ECC algorithm that detects and corrects 1 bit
 * errors in a 256 byte block of data.
 *
 * drivers/mtd/nand/nand_ecc.c
 *
 * Copyright 漏 2008 Koninklijke Philips Electronics NV.
 *                  Author: Frans Meulenbroeks
 *
 * Completely replaces the previous ECC implementation which was written by:
 *   Steven J. Hill ([email protected])
 *   Thomas Gleixner ([email protected])
 *
 * Information on how this algorithm works and how it was developed
 * can be found in Documentation/mtd/nand_ecc.txt
 *
 * This file is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 or (at your option) any
 * later version.
 *
 * This file is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this file; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 */

/*
 * The STANDALONE macro is useful when running the code outside the kernel
 * e.g. when running the code in a testbed or a benchmark program.
 * When STANDALONE is used, the module related macros are commented out
 * as well as the linux include files.
 * Instead a private definition of mtd_info is given to satisfy the compiler
 * (the code does not use mtd_info, so the code does not care)
 */
#ifndef STANDALONE
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#else
#include 
struct mtd_info;
#define EXPORT_SYMBOL(x)  /* x */

#define MODULE_LICENSE(x)	/* x */
#define MODULE_AUTHOR(x)	/* x */
#define MODULE_DESCRIPTION(x)	/* x */

#define printk printf
#define KERN_ERR		""
#endif

/*
 * invparity is a 256 byte table that contains the odd parity
 * for each byte. So if the number of bits in a byte is even,
 * the array element is 1, and when the number of bits is odd
 * the array eleemnt is 0.
 */
static const char invparity[256] = {
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
};

/*
 * bitsperbyte contains the number of bits per byte
 * this is only used for testing and repairing parity
 * (a precalculated value slightly improves performance)
 */
static const char bitsperbyte[256] = {
	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
};

/*
 * addressbits is a lookup table to filter out the bits from the xor-ed
 * ecc data that identify the faulty location.
 * this is only used for repairing parity
 * see the comments in nand_correct_data for more details
 */
static const char addressbits[256] = {
	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f
};

/**
 * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte
 *			 block
 * @mtd:	MTD block structure
 * @buf:	input buffer with raw data
 * @code:	output buffer with ECC
 */
int nand_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf,
		       unsigned char *code)
{
	int i;
	const uint32_t *bp = (uint32_t *)buf;
	/* 256 or 512 bytes/ecc  */
	const uint32_t eccsize_mult =
			(((struct nand_chip *)mtd->priv)->ecc.size) >> 8;
	uint32_t cur;		/* current value in buffer */
	/* rp0..rp15..rp17 are the various accumulated parities (per byte) */
	uint32_t rp0, rp1, rp2, rp3, rp4, rp5, rp6, rp7;
	uint32_t rp8, rp9, rp10, rp11, rp12, rp13, rp14, rp15, rp16;
	uint32_t uninitialized_var(rp17);	/* to make compiler happy */
	uint32_t par;		/* the cumulative parity for all data */
	uint32_t tmppar;	/* the cumulative parity for this iteration;
				   for rp12, rp14 and rp16 at the end of the
				   loop */

	par = 0;
	rp4 = 0;
	rp6 = 0;
	rp8 = 0;
	rp10 = 0;
	rp12 = 0;
	rp14 = 0;
	rp16 = 0;

	/*
	 * The loop is unrolled a number of times;
	 * This avoids if statements to decide on which rp value to update
	 * Also we process the data by longwords.
	 * Note: passing unaligned data might give a performance penalty.
	 * It is assumed that the buffers are aligned.
	 * tmppar is the cumulative sum of this iteration.
	 * needed for calculating rp12, rp14, rp16 and par
	 * also used as a performance improvement for rp6, rp8 and rp10
	 */
	for (i = 0; i < eccsize_mult << 2; i++) {
		cur = *bp++;
		tmppar = cur;
		rp4 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp6 ^= tmppar;
		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp8 ^= tmppar;

		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		rp6 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp6 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp10 ^= tmppar;

		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		rp6 ^= cur;
		rp8 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp6 ^= cur;
		rp8 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		rp8 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp8 ^= cur;

		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		rp6 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp6 ^= cur;
		cur = *bp++;
		tmppar ^= cur;
		rp4 ^= cur;
		cur = *bp++;
		tmppar ^= cur;

		par ^= tmppar;
		if ((i & 0x1) == 0)
			rp12 ^= tmppar;
		if ((i & 0x2) == 0)
			rp14 ^= tmppar;
		if (eccsize_mult == 2 && (i & 0x4) == 0)
			rp16 ^= tmppar;
	}

	/*
	 * handle the fact that we use longword operations
	 * we'll bring rp4..rp14..rp16 back to single byte entities by
	 * shifting and xoring first fold the upper and lower 16 bits,
	 * then the upper and lower 8 bits.
	 */
	rp4 ^= (rp4 >> 16);
	rp4 ^= (rp4 >> 8);
	rp4 &= 0xff;
	rp6 ^= (rp6 >> 16);
	rp6 ^= (rp6 >> 8);
	rp6 &= 0xff;
	rp8 ^= (rp8 >> 16);
	rp8 ^= (rp8 >> 8);
	rp8 &= 0xff;
	rp10 ^= (rp10 >> 16);
	rp10 ^= (rp10 >> 8);
	rp10 &= 0xff;
	rp12 ^= (rp12 >> 16);
	rp12 ^= (rp12 >> 8);
	rp12 &= 0xff;
	rp14 ^= (rp14 >> 16);
	rp14 ^= (rp14 >> 8);
	rp14 &= 0xff;
	if (eccsize_mult == 2) {
		rp16 ^= (rp16 >> 16);
		rp16 ^= (rp16 >> 8);
		rp16 &= 0xff;
	}

	/*
	 * we also need to calculate the row parity for rp0..rp3
	 * This is present in par, because par is now
	 * rp3 rp3 rp2 rp2 in little endian and
	 * rp2 rp2 rp3 rp3 in big endian
	 * as well as
	 * rp1 rp0 rp1 rp0 in little endian and
	 * rp0 rp1 rp0 rp1 in big endian
	 * First calculate rp2 and rp3
	 */
#ifdef __BIG_ENDIAN
	rp2 = (par >> 16);
	rp2 ^= (rp2 >> 8);
	rp2 &= 0xff;
	rp3 = par & 0xffff;
	rp3 ^= (rp3 >> 8);
	rp3 &= 0xff;
#else
	rp3 = (par >> 16);
	rp3 ^= (rp3 >> 8);
	rp3 &= 0xff;
	rp2 = par & 0xffff;
	rp2 ^= (rp2 >> 8);
	rp2 &= 0xff;
#endif

	/* reduce par to 16 bits then calculate rp1 and rp0 */
	par ^= (par >> 16);
#ifdef __BIG_ENDIAN
	rp0 = (par >> 8) & 0xff;
	rp1 = (par & 0xff);
#else
	rp1 = (par >> 8) & 0xff;
	rp0 = (par & 0xff);
#endif

	/* finally reduce par to 8 bits */
	par ^= (par >> 8);
	par &= 0xff;

	/*
	 * and calculate rp5..rp15..rp17
	 * note that par = rp4 ^ rp5 and due to the commutative property
	 * of the ^ operator we can say:
	 * rp5 = (par ^ rp4);
	 * The & 0xff seems superfluous, but benchmarking learned that
	 * leaving it out gives slightly worse results. No idea why, probably
	 * it has to do with the way the pipeline in pentium is organized.
	 */
	rp5 = (par ^ rp4) & 0xff;
	rp7 = (par ^ rp6) & 0xff;
	rp9 = (par ^ rp8) & 0xff;
	rp11 = (par ^ rp10) & 0xff;
	rp13 = (par ^ rp12) & 0xff;
	rp15 = (par ^ rp14) & 0xff;
	if (eccsize_mult == 2)
		rp17 = (par ^ rp16) & 0xff;

	/*
	 * Finally calculate the ecc bits.
	 * Again here it might seem that there are performance optimisations
	 * possible, but benchmarks showed that on the system this is developed
	 * the code below is the fastest
	 */
#ifdef CONFIG_MTD_NAND_ECC_SMC
	code[0] =
	    (invparity[rp7] << 7) |
	    (invparity[rp6] << 6) |
	    (invparity[rp5] << 5) |
	    (invparity[rp4] << 4) |
	    (invparity[rp3] << 3) |
	    (invparity[rp2] << 2) |
	    (invparity[rp1] << 1) |
	    (invparity[rp0]);
	code[1] =
	    (invparity[rp15] << 7) |
	    (invparity[rp14] << 6) |
	    (invparity[rp13] << 5) |
	    (invparity[rp12] << 4) |
	    (invparity[rp11] << 3) |
	    (invparity[rp10] << 2) |
	    (invparity[rp9] << 1)  |
	    (invparity[rp8]);
#else
	code[1] =
	    (invparity[rp7] << 7) |
	    (invparity[rp6] << 6) |
	    (invparity[rp5] << 5) |
	    (invparity[rp4] << 4) |
	    (invparity[rp3] << 3) |
	    (invparity[rp2] << 2) |
	    (invparity[rp1] << 1) |
	    (invparity[rp0]);
	code[0] =
	    (invparity[rp15] << 7) |
	    (invparity[rp14] << 6) |
	    (invparity[rp13] << 5) |
	    (invparity[rp12] << 4) |
	    (invparity[rp11] << 3) |
	    (invparity[rp10] << 2) |
	    (invparity[rp9] << 1)  |
	    (invparity[rp8]);
#endif
	if (eccsize_mult == 1)
		code[2] =
		    (invparity[par & 0xf0] << 7) |
		    (invparity[par & 0x0f] << 6) |
		    (invparity[par & 0xcc] << 5) |
		    (invparity[par & 0x33] << 4) |
		    (invparity[par & 0xaa] << 3) |
		    (invparity[par & 0x55] << 2) |
		    3;
	else
		code[2] =
		    (invparity[par & 0xf0] << 7) |
		    (invparity[par & 0x0f] << 6) |
		    (invparity[par & 0xcc] << 5) |
		    (invparity[par & 0x33] << 4) |
		    (invparity[par & 0xaa] << 3) |
		    (invparity[par & 0x55] << 2) |
		    (invparity[rp17] << 1) |
		    (invparity[rp16] << 0);
	return 0;
}
EXPORT_SYMBOL(nand_calculate_ecc);

/**
 * __nand_correct_data - [NAND Interface] Detect and correct bit error(s)
 * @buf:	raw data read from the chip
 * @read_ecc:	ECC from the chip
 * @calc_ecc:	the ECC calculated from raw data
 * @eccsize:	data bytes per ecc step (256 or 512)
 *
 * Detect and correct a 1 bit error for eccsize byte block
 */
int __nand_correct_data(unsigned char *buf,
			unsigned char *read_ecc, unsigned char *calc_ecc,
			unsigned int eccsize)
{
	unsigned char b0, b1, b2, bit_addr;
	unsigned int byte_addr;
	/* 256 or 512 bytes/ecc  */
	const uint32_t eccsize_mult = eccsize >> 8;

	/*
	 * b0 to b2 indicate which bit is faulty (if any)
	 * we might need the xor result  more than once,
	 * so keep them in a local var
	*/
#ifdef CONFIG_MTD_NAND_ECC_SMC
	b0 = read_ecc[0] ^ calc_ecc[0];
	b1 = read_ecc[1] ^ calc_ecc[1];
#else
	b0 = read_ecc[1] ^ calc_ecc[1];
	b1 = read_ecc[0] ^ calc_ecc[0];
#endif
	b2 = read_ecc[2] ^ calc_ecc[2];

	/* check if there are any bitfaults */

	/* repeated if statements are slightly more efficient than switch ... */
	/* ordered in order of likelihood */

	if ((b0 | b1 | b2) == 0)
		return 0;	/* no error */

	if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) &&
	    (((b1 ^ (b1 >> 1)) & 0x55) == 0x55) &&
	    ((eccsize_mult == 1 && ((b2 ^ (b2 >> 1)) & 0x54) == 0x54) ||
	     (eccsize_mult == 2 && ((b2 ^ (b2 >> 1)) & 0x55) == 0x55))) {
	/* single bit error */
		/*
		 * rp17/rp15/13/11/9/7/5/3/1 indicate which byte is the faulty
		 * byte, cp 5/3/1 indicate the faulty bit.
		 * A lookup table (called addressbits) is used to filter
		 * the bits from the byte they are in.
		 * A marginal optimisation is possible by having three
		 * different lookup tables.
		 * One as we have now (for b0), one for b2
		 * (that would avoid the >> 1), and one for b1 (with all values
		 * << 4). However it was felt that introducing two more tables
		 * hardly justify the gain.
		 *
		 * The b2 shift is there to get rid of the lowest two bits.
		 * We could also do addressbits[b2] >> 1 but for the
		 * performace it does not make any difference
		 */
		if (eccsize_mult == 1)
			byte_addr = (addressbits[b1] << 4) + addressbits[b0];
		else
			byte_addr = (addressbits[b2 & 0x3] << 8) +
				    (addressbits[b1] << 4) + addressbits[b0];
		bit_addr = addressbits[b2 >> 2];
		/* flip the bit */
		buf[byte_addr] ^= (1 << bit_addr);
		return 1;

	}
	/* count nr of bits; use table lookup, faster than calculating it */
	if ((bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]) == 1)
		return 1;	/* error in ecc data; no action needed */

	printk(KERN_ERR "uncorrectable error : ");
	return -1;
}
EXPORT_SYMBOL(__nand_correct_data);

/**
 * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
 * @mtd:	MTD block structure
 * @buf:	raw data read from the chip
 * @read_ecc:	ECC from the chip
 * @calc_ecc:	the ECC calculated from raw data
 *
 * Detect and correct a 1 bit error for 256/512 byte block
 */
int nand_correct_data(struct mtd_info *mtd, unsigned char *buf,
		      unsigned char *read_ecc, unsigned char *calc_ecc)
{
	return __nand_correct_data(buf, read_ecc, calc_ecc,
				   ((struct nand_chip *)mtd->priv)->ecc.size);
}
EXPORT_SYMBOL(nand_correct_data);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Frans Meulenbroeks ");
MODULE_DESCRIPTION("Generic NAND ECC support");


drivers/mtd/nand/nand_base.c

nand flash linux驱动最重要的核心层代码,自己的驱动程序多看看这个核心层的调用,就清楚怎么写了。包括flash的识别,识别后扫描坏块,建立坏块表,读写、擦除flash,读写oob,ecc校验,都是在这个里面完成。


/*
 *  drivers/mtd/nand.c
 *
 *  Overview:
 *   This is the generic MTD driver for NAND flash devices. It should be
 *   capable of working with almost all NAND chips currently available.
 *   Basic support for AG-AND chips is provided.
 *
 *	Additional technical information is available on
 *	http://www.linux-mtd.infradead.org/doc/nand.html
 *
 *  Copyright (C) 2000 Steven J. Hill ([email protected])
 *		  2002-2006 Thomas Gleixner ([email protected])
 *
 *  Credits:
 *	David Woodhouse for adding multichip support
 *
 *	Aleph One Ltd. and Toby Churchill Ltd. for supporting the
 *	rework for 2K page size chips
 *
 *  TODO:
 *	Enable cached programming for 2k page size chips
 *	Check, if mtd->ecctype should be set to MTD_ECC_HW
 *	if we have HW ecc support.
 *	The AG-AND chips have nice features for speed improvement,
 *	which are not supported yet. Read / program 4 pages in one go.
 *	BBT table is not serialized, has to be fixed
 *
 * 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.
 *
 */

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#ifdef CONFIG_MTD_PARTITIONS
#include 
#endif

/* Define default oob placement schemes for large and small page devices */
static struct nand_ecclayout nand_oob_8 = {
	.eccbytes = 3,
	.eccpos = {0, 1, 2},
	.oobfree = {
		{.offset = 3,
		 .length = 2},
		{.offset = 6,
		 .length = 2}}
};

static struct nand_ecclayout nand_oob_16 = {
	.eccbytes = 6,
	.eccpos = {0, 1, 2, 3, 6, 7},
	.oobfree = {
		{.offset = 8,
		 . length = 8}}
};

static struct nand_ecclayout nand_oob_64 = {
	.eccbytes = 24,
	.eccpos = {
		   40, 41, 42, 43, 44, 45, 46, 47,
		   48, 49, 50, 51, 52, 53, 54, 55,
		   56, 57, 58, 59, 60, 61, 62, 63},
	.oobfree = {
		{.offset = 2,
		 .length = 38}}
};

static struct nand_ecclayout nand_oob_128 = {
	.eccbytes = 48,
	.eccpos = {
		   80, 81, 82, 83, 84, 85, 86, 87,
		   88, 89, 90, 91, 92, 93, 94, 95,
		   96, 97, 98, 99, 100, 101, 102, 103,
		   104, 105, 106, 107, 108, 109, 110, 111,
		   112, 113, 114, 115, 116, 117, 118, 119,
		   120, 121, 122, 123, 124, 125, 126, 127},
	.oobfree = {
		{.offset = 2,
		 .length = 78}}
};
static struct nand_ecclayout nand_oob_224 = {
	.eccbytes = 48,
	.eccpos = {
		   80, 81, 82, 83, 84, 85, 86, 87,
		   88, 89, 90, 91, 92, 93, 94, 95,
		   96, 97, 98, 99, 100, 101, 102, 103,
		   104, 105, 106, 107, 108, 109, 110, 111,
		   112, 113, 114, 115, 116, 117, 118, 119,
		   120, 121, 122, 123, 124, 125, 126, 127},
	.oobfree = {
		{.offset = 2,
		 .length = 78}}
};

static int nand_get_device(struct nand_chip *chip, struct mtd_info *mtd,
			   int new_state);

static int nand_do_write_oob(struct mtd_info *mtd, loff_t to,
			     struct mtd_oob_ops *ops);

/*
 * For devices which display every fart in the system on a separate LED. Is
 * compiled away when LED support is disabled.
 */
DEFINE_LED_TRIGGER(nand_led_trigger);

/**
 * nand_release_device - [GENERIC] release chip
 * @mtd:	MTD device structure
 *
 * Deselect, release chip lock and wake up anyone waiting on the device
 */
static void nand_release_device(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;

	/* De-select the NAND device */
	chip->select_chip(mtd, -1);

	/* Release the controller and the chip */
	spin_lock(&chip->controller->lock);
	chip->controller->active = NULL;
	chip->state = FL_READY;
	wake_up(&chip->controller->wq);
	spin_unlock(&chip->controller->lock);
}

/**
 * nand_read_byte - [DEFAULT] read one byte from the chip
 * @mtd:	MTD device structure
 *
 * Default read function for 8bit buswith
 */
static uint8_t nand_read_byte(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	return readb(chip->IO_ADDR_R);
}

/**
 * nand_read_byte16 - [DEFAULT] read one byte endianess aware from the chip
 * @mtd:	MTD device structure
 *
 * Default read function for 16bit buswith with
 * endianess conversion
 */
static uint8_t nand_read_byte16(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	return (uint8_t) cpu_to_le16(readw(chip->IO_ADDR_R));
}

/**
 * nand_read_word - [DEFAULT] read one word from the chip
 * @mtd:	MTD device structure
 *
 * Default read function for 16bit buswith without
 * endianess conversion
 */
static u16 nand_read_word(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	return readw(chip->IO_ADDR_R);
}

/**
 * nand_select_chip - [DEFAULT] control CE line
 * @mtd:	MTD device structure
 * @chipnr:	chipnumber to select, -1 for deselect
 *
 * Default select function for 1 chip devices.
 */
static void nand_select_chip(struct mtd_info *mtd, int chipnr)
{
	struct nand_chip *chip = mtd->priv;

	switch (chipnr) {
	case -1:
		chip->cmd_ctrl(mtd, NAND_CMD_NONE, 0 | NAND_CTRL_CHANGE);
		break;
	case 0:
		break;

	default:
		BUG();
	}
}

/**
 * nand_write_buf - [DEFAULT] write buffer to chip
 * @mtd:	MTD device structure
 * @buf:	data buffer
 * @len:	number of bytes to write
 *
 * Default write function for 8bit buswith
 */
static void nand_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;

	for (i = 0; i < len; i++)
		writeb(buf[i], chip->IO_ADDR_W);
}

/**
 * nand_read_buf - [DEFAULT] read chip data into buffer
 * @mtd:	MTD device structure
 * @buf:	buffer to store date
 * @len:	number of bytes to read
 *
 * Default read function for 8bit buswith
 */
static void nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;

	for (i = 0; i < len; i++)
		buf[i] = readb(chip->IO_ADDR_R);
}

/**
 * nand_verify_buf - [DEFAULT] Verify chip data against buffer
 * @mtd:	MTD device structure
 * @buf:	buffer containing the data to compare
 * @len:	number of bytes to compare
 *
 * Default verify function for 8bit buswith
 */
static int nand_verify_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;

	for (i = 0; i < len; i++)
		if (buf[i] != readb(chip->IO_ADDR_R))
			return -EFAULT;
	return 0;
}

/**
 * nand_write_buf16 - [DEFAULT] write buffer to chip
 * @mtd:	MTD device structure
 * @buf:	data buffer
 * @len:	number of bytes to write
 *
 * Default write function for 16bit buswith
 */
static void nand_write_buf16(struct mtd_info *mtd, const uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;
	u16 *p = (u16 *) buf;
	len >>= 1;

	for (i = 0; i < len; i++)
		writew(p[i], chip->IO_ADDR_W);

}

/**
 * nand_read_buf16 - [DEFAULT] read chip data into buffer
 * @mtd:	MTD device structure
 * @buf:	buffer to store date
 * @len:	number of bytes to read
 *
 * Default read function for 16bit buswith
 */
static void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;
	u16 *p = (u16 *) buf;
	len >>= 1;

	for (i = 0; i < len; i++)
		p[i] = readw(chip->IO_ADDR_R);
}

/**
 * nand_verify_buf16 - [DEFAULT] Verify chip data against buffer
 * @mtd:	MTD device structure
 * @buf:	buffer containing the data to compare
 * @len:	number of bytes to compare
 *
 * Default verify function for 16bit buswith
 */
static int nand_verify_buf16(struct mtd_info *mtd, const uint8_t *buf, int len)
{
	int i;
	struct nand_chip *chip = mtd->priv;
	u16 *p = (u16 *) buf;
	len >>= 1;

	for (i = 0; i < len; i++)
		if (p[i] != readw(chip->IO_ADDR_R))
			return -EFAULT;

	return 0;
}

/**
 * nand_block_bad - [DEFAULT] Read bad block marker from the chip
 * @mtd:	MTD device structure
 * @ofs:	offset from device start
 * @getchip:	0, if the chip is already selected
 *
 * Check, if the block is bad.
 */
static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
{
	int page, chipnr, res = 0;
	struct nand_chip *chip = mtd->priv;
	u16 bad;

	page = (int)(ofs >> chip->page_shift) & chip->pagemask;

	if (getchip) {
		chipnr = (int)(ofs >> chip->chip_shift);

		nand_get_device(chip, mtd, FL_READING);

		/* Select the NAND device */
		chip->select_chip(mtd, chipnr);
	}

	if (chip->options & NAND_BUSWIDTH_16) {
		chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos & 0xFE,
			      page);
		bad = cpu_to_le16(chip->read_word(mtd));
		if (chip->badblockpos & 0x1)
			bad >>= 8;
		if ((bad & 0xFF) != 0xff)
			res = 1;
	} else {
		chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos, page);
		if (chip->read_byte(mtd) != 0xff)
			res = 1;
	}

	if (getchip)
		nand_release_device(mtd);

	return res;
}

/**
 * nand_default_block_markbad - [DEFAULT] mark a block bad
 * @mtd:	MTD device structure
 * @ofs:	offset from device start
 *
 * This is the default implementation, which can be overridden by
 * a hardware specific driver.
*/
static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
{
	struct nand_chip *chip = mtd->priv;
	uint8_t buf[2] = { 0, 0 };
	int block, ret;

	/* Get block number */
	block = (int)(ofs >> chip->bbt_erase_shift);
	if (chip->bbt)
		chip->bbt[block >> 2] |= 0x01 << ((block & 0x03) << 1);

	/* Do we have a flash based bad block table ? */
	if (chip->options & NAND_USE_FLASH_BBT)
		ret = nand_update_bbt(mtd, ofs);
	else {
		/* We write two bytes, so we dont have to mess with 16 bit
		 * access
		 */
		nand_get_device(chip, mtd, FL_WRITING);
		ofs += mtd->oobsize;
		chip->ops.len = chip->ops.ooblen = 2;
		chip->ops.datbuf = NULL;
		chip->ops.oobbuf = buf;
		chip->ops.ooboffs = chip->badblockpos & ~0x01;

		ret = nand_do_write_oob(mtd, ofs, &chip->ops);
		nand_release_device(mtd);
	}
	if (!ret)
		mtd->ecc_stats.badblocks++;

	return ret;
}

/**
 * nand_check_wp - [GENERIC] check if the chip is write protected
 * @mtd:	MTD device structure
 * Check, if the device is write protected
 *
 * The function expects, that the device is already selected
 */
static int nand_check_wp(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	/* Check the WP bit */
	chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
	return (chip->read_byte(mtd) & NAND_STATUS_WP) ? 0 : 1;
}

/**
 * nand_block_checkbad - [GENERIC] Check if a block is marked bad
 * @mtd:	MTD device structure
 * @ofs:	offset from device start
 * @getchip:	0, if the chip is already selected
 * @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 nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
			       int allowbbt)
{
	struct nand_chip *chip = mtd->priv;

	if (!chip->bbt)
		return chip->block_bad(mtd, ofs, getchip);

	/* Return info from the table */
	return nand_isbad_bbt(mtd, ofs, allowbbt);
}

/*
 * Wait for the ready pin, after a command
 * The timeout is catched later.
 */
void nand_wait_ready(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	unsigned long timeo = jiffies + 2;

	led_trigger_event(nand_led_trigger, LED_FULL);
	/* wait until command is processed or timeout occures */
	do {
		if (chip->dev_ready(mtd))
			break;
		touch_softlockup_watchdog();
	} while (time_before(jiffies, timeo));
	led_trigger_event(nand_led_trigger, LED_OFF);
}
EXPORT_SYMBOL_GPL(nand_wait_ready);

/**
 * nand_command - [DEFAULT] Send command to NAND device
 * @mtd:	MTD device structure
 * @command:	the command to be sent
 * @column:	the column address for this command, -1 if none
 * @page_addr:	the page address for this command, -1 if none
 *
 * Send command to NAND device. This function is used for small page
 * devices (256/512 Bytes per page)
 */
static void nand_command(struct mtd_info *mtd, unsigned int command,
			 int column, int page_addr)
{
	register struct nand_chip *chip = mtd->priv;
	int ctrl = NAND_CTRL_CLE | NAND_CTRL_CHANGE;

	/*
	 * Write out the command to the device.
	 */
	if (command == NAND_CMD_SEQIN) {
		int readcmd;

		if (column >= mtd->writesize) {
			/* OOB area */
			column -= mtd->writesize;
			readcmd = NAND_CMD_READOOB;
		} else if (column < 256) {
			/* First 256 bytes --> READ0 */
			readcmd = NAND_CMD_READ0;
		} else {
			column -= 256;
			readcmd = NAND_CMD_READ1;
		}
		chip->cmd_ctrl(mtd, readcmd, ctrl);
		ctrl &= ~NAND_CTRL_CHANGE;
	}
	chip->cmd_ctrl(mtd, command, ctrl);

	/*
	 * Address cycle, when necessary
	 */
	ctrl = NAND_CTRL_ALE | NAND_CTRL_CHANGE;
	/* Serially input address */
	if (column != -1) {
		/* Adjust columns for 16 bit buswidth */
		if (chip->options & NAND_BUSWIDTH_16)
			column >>= 1;
		chip->cmd_ctrl(mtd, column, ctrl);
		ctrl &= ~NAND_CTRL_CHANGE;
	}
	if (page_addr != -1) {
		chip->cmd_ctrl(mtd, page_addr, ctrl);
		ctrl &= ~NAND_CTRL_CHANGE;
		chip->cmd_ctrl(mtd, page_addr >> 8, ctrl);
		/* One more address cycle for devices > 32MiB */
		if (chip->chipsize > (32 << 20))
			chip->cmd_ctrl(mtd, page_addr >> 16, ctrl);
	}
	chip->cmd_ctrl(mtd, NAND_CMD_NONE, NAND_NCE | NAND_CTRL_CHANGE);

	/*
	 * program and erase have their own busy handlers
	 * status and sequential in needs no delay
	 */
	switch (command) {

	case NAND_CMD_PAGEPROG:
	case NAND_CMD_ERASE1:
	case NAND_CMD_ERASE2:
	case NAND_CMD_SEQIN:
	case NAND_CMD_STATUS:
		return;

	case NAND_CMD_RESET:
		if (chip->dev_ready)
			break;
		udelay(chip->chip_delay);
		chip->cmd_ctrl(mtd, NAND_CMD_STATUS,
			       NAND_CTRL_CLE | NAND_CTRL_CHANGE);
		chip->cmd_ctrl(mtd,
			       NAND_CMD_NONE, NAND_NCE | NAND_CTRL_CHANGE);
		while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) ;
		return;

		/* This applies to read commands */
	default:
		/*
		 * If we don't have access to the busy pin, we apply the given
		 * command delay
		 */
		if (!chip->dev_ready) {
			udelay(chip->chip_delay);
			return;
		}
	}
	/* Apply this short delay always to ensure that we do wait tWB in
	 * any case on any machine. */
	ndelay(100);

	nand_wait_ready(mtd);
}

/**
 * nand_command_lp - [DEFAULT] Send command to NAND large page device
 * @mtd:	MTD device structure
 * @command:	the command to be sent
 * @column:	the column address for this command, -1 if none
 * @page_addr:	the page address for this command, -1 if none
 *
 * Send command to NAND device. This is the version for the new large page
 * devices We dont have the separate regions as we have in the small page
 * devices.  We must emulate NAND_CMD_READOOB to keep the code compatible.
 */
static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
			    int column, int page_addr)
{
	register struct nand_chip *chip = mtd->priv;

	/* Emulate NAND_CMD_READOOB */
	if (command == NAND_CMD_READOOB) {
		column += mtd->writesize;
		command = NAND_CMD_READ0;
	}

	/* Command latch cycle */
	chip->cmd_ctrl(mtd, command & 0xff,
		       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);

	if (column != -1 || page_addr != -1) {
		int ctrl = NAND_CTRL_CHANGE | NAND_NCE | NAND_ALE;

		/* Serially input address */
		if (column != -1) {
			/* Adjust columns for 16 bit buswidth */
			if (chip->options & NAND_BUSWIDTH_16)
				column >>= 1;
			chip->cmd_ctrl(mtd, column, ctrl);
			ctrl &= ~NAND_CTRL_CHANGE;
			chip->cmd_ctrl(mtd, column >> 8, ctrl);
		}
		if (page_addr != -1) {
			chip->cmd_ctrl(mtd, page_addr, ctrl);
			chip->cmd_ctrl(mtd, page_addr >> 8,
				       NAND_NCE | NAND_ALE);
			/* One more address cycle for devices > 128MiB */
			if (chip->chipsize > (128 << 20))
				chip->cmd_ctrl(mtd, page_addr >> 16,
					       NAND_NCE | NAND_ALE);
		}
	}
	chip->cmd_ctrl(mtd, NAND_CMD_NONE, NAND_NCE | NAND_CTRL_CHANGE);

	/*
	 * program and erase have their own busy handlers
	 * status, sequential in, and deplete1 need no delay
	 */
	switch (command) {

	case NAND_CMD_CACHEDPROG:
	case NAND_CMD_PAGEPROG:
	case NAND_CMD_ERASE1:
	case NAND_CMD_ERASE2:
	case NAND_CMD_SEQIN:
	case NAND_CMD_RNDIN:
	case NAND_CMD_STATUS:
	case NAND_CMD_DEPLETE1:
		return;

		/*
		 * read error status commands require only a short delay
		 */
	case NAND_CMD_STATUS_ERROR:
	case NAND_CMD_STATUS_ERROR0:
	case NAND_CMD_STATUS_ERROR1:
	case NAND_CMD_STATUS_ERROR2:
	case NAND_CMD_STATUS_ERROR3:
		udelay(chip->chip_delay);
		return;

	case NAND_CMD_RESET:
		if (chip->dev_ready)
			break;
		udelay(chip->chip_delay);
		chip->cmd_ctrl(mtd, NAND_CMD_STATUS,
			       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
		chip->cmd_ctrl(mtd, NAND_CMD_NONE,
			       NAND_NCE | NAND_CTRL_CHANGE);
		while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) ;
		return;

	case NAND_CMD_RNDOUT:
		/* No ready / busy check necessary */
		chip->cmd_ctrl(mtd, NAND_CMD_RNDOUTSTART,
			       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
		chip->cmd_ctrl(mtd, NAND_CMD_NONE,
			       NAND_NCE | NAND_CTRL_CHANGE);
		return;

	case NAND_CMD_READ0:
		chip->cmd_ctrl(mtd, NAND_CMD_READSTART,
			       NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
		chip->cmd_ctrl(mtd, NAND_CMD_NONE,
			       NAND_NCE | NAND_CTRL_CHANGE);

		/* This applies to read commands */
	default:
		/*
		 * If we don't have access to the busy pin, we apply the given
		 * command delay
		 */
		if (!chip->dev_ready) {
			udelay(chip->chip_delay);
			return;
		}
	}

	/* Apply this short delay always to ensure that we do wait tWB in
	 * any case on any machine. */
	ndelay(100);

	nand_wait_ready(mtd);
}

/**
 * nand_get_device - [GENERIC] Get chip for selected access
 * @chip:	the nand chip descriptor
 * @mtd:	MTD device structure
 * @new_state:	the state which is requested
 *
 * Get the device and lock it for exclusive access
 */
static int
nand_get_device(struct nand_chip *chip, struct mtd_info *mtd, int new_state)
{
	spinlock_t *lock = &chip->controller->lock;
	wait_queue_head_t *wq = &chip->controller->wq;
	DECLARE_WAITQUEUE(wait, current);
 retry:
	spin_lock(lock);

	/* Hardware controller shared among independent devices */
	if (!chip->controller->active)
		chip->controller->active = chip;

	if (chip->controller->active == chip && chip->state == FL_READY) {
		chip->state = new_state;
		spin_unlock(lock);
		return 0;
	}
	if (new_state == FL_PM_SUSPENDED) {
		spin_unlock(lock);
		return (chip->state == FL_PM_SUSPENDED) ? 0 : -EAGAIN;
	}
	set_current_state(TASK_UNINTERRUPTIBLE);
	add_wait_queue(wq, &wait);
	spin_unlock(lock);
	schedule();
	remove_wait_queue(wq, &wait);
	goto retry;
}

/**
 * nand_wait - [DEFAULT]  wait until the command is done
 * @mtd:	MTD device structure
 * @chip:	NAND chip structure
 *
 * Wait for command done. This applies to erase and program only
 * Erase can take up to 400ms and program up to 20ms according to
 * general NAND and SmartMedia specs
 */
static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
{

	unsigned long timeo = jiffies;
	int status, state = chip->state;

	if (state == FL_ERASING)
		timeo += (HZ * 400) / 1000;
	else
		timeo += (HZ * 20) / 1000;

	led_trigger_event(nand_led_trigger, LED_FULL);

	/* Apply this short delay always to ensure that we do wait tWB in
	 * any case on any machine. */
	ndelay(100);

	if ((state == FL_ERASING) && (chip->options & NAND_IS_AND))
		chip->cmdfunc(mtd, NAND_CMD_STATUS_MULTI, -1, -1);
	else
		chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);

	while (time_before(jiffies, timeo)) {
		if (chip->dev_ready) {
			if (chip->dev_ready(mtd))
				break;
		} else {
			if (chip->read_byte(mtd) & NAND_STATUS_READY)
				break;
		}
		cond_resched();
	}
	led_trigger_event(nand_led_trigger, LED_OFF);

	status = (int)chip->read_byte(mtd);
	return status;
}

/**
 * nand_read_page_raw - [Intern] read raw page data without ecc
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 *
 * Not for syndrome calculating ecc controllers, which use a special oob layout
 */
static int nand_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
			      uint8_t *buf, int page)
{
	chip->read_buf(mtd, buf, mtd->writesize);
	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
	return 0;
}

/**
 * nand_read_page_raw_syndrome - [Intern] read raw page data without ecc
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 *
 * We need a special oob layout and handling even when OOB isn't used.
 */
static int nand_read_page_raw_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
			      uint8_t *buf, int page)
{
	int eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	uint8_t *oob = chip->oob_poi;
	int steps, size;

	for (steps = chip->ecc.steps; steps > 0; steps--) {
		chip->read_buf(mtd, buf, eccsize);
		buf += eccsize;

		if (chip->ecc.prepad) {
			chip->read_buf(mtd, oob, chip->ecc.prepad);
			oob += chip->ecc.prepad;
		}

		chip->read_buf(mtd, oob, eccbytes);
		oob += eccbytes;

		if (chip->ecc.postpad) {
			chip->read_buf(mtd, oob, chip->ecc.postpad);
			oob += chip->ecc.postpad;
		}
	}

	size = mtd->oobsize - (oob - chip->oob_poi);
	if (size)
		chip->read_buf(mtd, oob, size);

	return 0;
}

/**
 * nand_read_page_swecc - [REPLACABLE] software ecc based page read function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 */
static int nand_read_page_swecc(struct mtd_info *mtd, struct nand_chip *chip,
				uint8_t *buf, int page)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *p = buf;
	uint8_t *ecc_calc = chip->buffers->ecccalc;
	uint8_t *ecc_code = chip->buffers->ecccode;
	uint32_t *eccpos = chip->ecc.layout->eccpos;

	chip->ecc.read_page_raw(mtd, chip, buf, page);

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);

	for (i = 0; i < chip->ecc.total; i++)
		ecc_code[i] = chip->oob_poi[eccpos[i]];

	eccsteps = chip->ecc.steps;
	p = buf;

	for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		int stat;

		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
		if (stat < 0)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;
	}
	return 0;
}

/**
 * nand_read_subpage - [REPLACABLE] software ecc based sub-page read function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @data_offs:	offset of requested data within the page
 * @readlen:	data length
 * @bufpoi:	buffer to store read data
 */
static int nand_read_subpage(struct mtd_info *mtd, struct nand_chip *chip, uint32_t data_offs, uint32_t readlen, uint8_t *bufpoi)
{
	int start_step, end_step, num_steps;
	uint32_t *eccpos = chip->ecc.layout->eccpos;
	uint8_t *p;
	int data_col_addr, i, gaps = 0;
	int datafrag_len, eccfrag_len, aligned_len, aligned_pos;
	int busw = (chip->options & NAND_BUSWIDTH_16) ? 2 : 1;

	/* Column address wihin the page aligned to ECC size (256bytes). */
	start_step = data_offs / chip->ecc.size;
	end_step = (data_offs + readlen - 1) / chip->ecc.size;
	num_steps = end_step - start_step + 1;

	/* Data size aligned to ECC ecc.size*/
	datafrag_len = num_steps * chip->ecc.size;
	eccfrag_len = num_steps * chip->ecc.bytes;

	data_col_addr = start_step * chip->ecc.size;
	/* If we read not a page aligned data */
	if (data_col_addr != 0)
		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, data_col_addr, -1);

	p = bufpoi + data_col_addr;
	chip->read_buf(mtd, p, datafrag_len);

	/* Calculate  ECC */
	for (i = 0; i < eccfrag_len ; i += chip->ecc.bytes, p += chip->ecc.size)
		chip->ecc.calculate(mtd, p, &chip->buffers->ecccalc[i]);

	/* The performance is faster if to position offsets
	   according to ecc.pos. Let make sure here that
	   there are no gaps in ecc positions */
	for (i = 0; i < eccfrag_len - 1; i++) {
		if (eccpos[i + start_step * chip->ecc.bytes] + 1 !=
			eccpos[i + start_step * chip->ecc.bytes + 1]) {
			gaps = 1;
			break;
		}
	}
	if (gaps) {
		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize, -1);
		chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
	} else {
		/* send the command to read the particular ecc bytes */
		/* take care about buswidth alignment in read_buf */
		aligned_pos = eccpos[start_step * chip->ecc.bytes] & ~(busw - 1);
		aligned_len = eccfrag_len;
		if (eccpos[start_step * chip->ecc.bytes] & (busw - 1))
			aligned_len++;
		if (eccpos[(start_step + num_steps) * chip->ecc.bytes] & (busw - 1))
			aligned_len++;

		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize + aligned_pos, -1);
		chip->read_buf(mtd, &chip->oob_poi[aligned_pos], aligned_len);
	}

	for (i = 0; i < eccfrag_len; i++)
		chip->buffers->ecccode[i] = chip->oob_poi[eccpos[i + start_step * chip->ecc.bytes]];

	p = bufpoi + data_col_addr;
	for (i = 0; i < eccfrag_len ; i += chip->ecc.bytes, p += chip->ecc.size) {
		int stat;

		stat = chip->ecc.correct(mtd, p, &chip->buffers->ecccode[i], &chip->buffers->ecccalc[i]);
		if (stat == -1)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;
	}
	return 0;
}

/**
 * nand_read_page_hwecc - [REPLACABLE] hardware ecc based page read function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 *
 * Not for syndrome calculating ecc controllers which need a special oob layout
 */
static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
				uint8_t *buf, int page)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *p = buf;
	uint8_t *ecc_calc = chip->buffers->ecccalc;
	uint8_t *ecc_code = chip->buffers->ecccode;
	uint32_t *eccpos = chip->ecc.layout->eccpos;

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		chip->ecc.hwctl(mtd, NAND_ECC_READ);
		chip->read_buf(mtd, p, eccsize);
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
	}
	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);

	for (i = 0; i < chip->ecc.total; i++)
		ecc_code[i] = chip->oob_poi[eccpos[i]];

	eccsteps = chip->ecc.steps;
	p = buf;

	for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		int stat;

		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
		if (stat < 0)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;
	}
	return 0;
}

/**
 * nand_read_page_hwecc_oob_first - [REPLACABLE] hw ecc, read oob first
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 *
 * Hardware ECC for large page chips, require OOB to be read first.
 * For this ECC mode, the write_page method is re-used from ECC_HW.
 * These methods read/write ECC from the OOB area, unlike the
 * ECC_HW_SYNDROME support with multiple ECC steps, follows the
 * "infix ECC" scheme and reads/writes ECC from the data area, by
 * overwriting the NAND manufacturer bad block markings.
 */
static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd,
	struct nand_chip *chip, uint8_t *buf, int page)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *p = buf;
	uint8_t *ecc_code = chip->buffers->ecccode;
	uint32_t *eccpos = chip->ecc.layout->eccpos;
	uint8_t *ecc_calc = chip->buffers->ecccalc;

	/* Read the OOB area first */
	chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);

	for (i = 0; i < chip->ecc.total; i++)
		ecc_code[i] = chip->oob_poi[eccpos[i]];

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		int stat;

		chip->ecc.hwctl(mtd, NAND_ECC_READ);
		chip->read_buf(mtd, p, eccsize);
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);

		stat = chip->ecc.correct(mtd, p, &ecc_code[i], NULL);
		if (stat < 0)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;
	}
	return 0;
}

/**
 * nand_read_page_syndrome - [REPLACABLE] hardware ecc syndrom based page read
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @page:	page number to read
 *
 * The hw generator calculates the error syndrome automatically. Therefor
 * we need a special oob layout and handling.
 */
static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
				   uint8_t *buf, int page)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *p = buf;
	uint8_t *oob = chip->oob_poi;

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		int stat;

		chip->ecc.hwctl(mtd, NAND_ECC_READ);
		chip->read_buf(mtd, p, eccsize);

		if (chip->ecc.prepad) {
			chip->read_buf(mtd, oob, chip->ecc.prepad);
			oob += chip->ecc.prepad;
		}

		chip->ecc.hwctl(mtd, NAND_ECC_READSYN);
		chip->read_buf(mtd, oob, eccbytes);
		stat = chip->ecc.correct(mtd, p, oob, NULL);

		if (stat < 0)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;

		oob += eccbytes;

		if (chip->ecc.postpad) {
			chip->read_buf(mtd, oob, chip->ecc.postpad);
			oob += chip->ecc.postpad;
		}
	}

	/* Calculate remaining oob bytes */
	i = mtd->oobsize - (oob - chip->oob_poi);
	if (i)
		chip->read_buf(mtd, oob, i);

	return 0;
}

/**
 * nand_transfer_oob - [Internal] Transfer oob to client buffer
 * @chip:	nand chip structure
 * @oob:	oob destination address
 * @ops:	oob ops structure
 * @len:	size of oob to transfer
 */
static uint8_t *nand_transfer_oob(struct nand_chip *chip, uint8_t *oob,
				  struct mtd_oob_ops *ops, size_t len)
{
	switch(ops->mode) {

	case MTD_OOB_PLACE:
	case MTD_OOB_RAW:
		memcpy(oob, chip->oob_poi + ops->ooboffs, len);
		return oob + len;

	case MTD_OOB_AUTO: {
		struct nand_oobfree *free = chip->ecc.layout->oobfree;
		uint32_t boffs = 0, roffs = ops->ooboffs;
		size_t bytes = 0;

		for(; free->length && len; free++, len -= bytes) {
			/* Read request not from offset 0 ? */
			if (unlikely(roffs)) {
				if (roffs >= free->length) {
					roffs -= free->length;
					continue;
				}
				boffs = free->offset + roffs;
				bytes = min_t(size_t, len,
					      (free->length - roffs));
				roffs = 0;
			} else {
				bytes = min_t(size_t, len, free->length);
				boffs = free->offset;
			}
			memcpy(oob, chip->oob_poi + boffs, bytes);
			oob += bytes;
		}
		return oob;
	}
	default:
		BUG();
	}
	return NULL;
}

/**
 * nand_do_read_ops - [Internal] Read data with ECC
 *
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @ops:	oob ops structure
 *
 * Internal function. Called with chip held.
 */
static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
			    struct mtd_oob_ops *ops)
{
	int chipnr, page, realpage, col, bytes, aligned;
	struct nand_chip *chip = mtd->priv;
	struct mtd_ecc_stats stats;
	int blkcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;
	int sndcmd = 1;
	int ret = 0;
	uint32_t readlen = ops->len;
	uint32_t oobreadlen = ops->ooblen;
	uint8_t *bufpoi, *oob, *buf;

	stats = mtd->ecc_stats;

	chipnr = (int)(from >> chip->chip_shift);
	chip->select_chip(mtd, chipnr);

	realpage = (int)(from >> chip->page_shift);
	page = realpage & chip->pagemask;

	col = (int)(from & (mtd->writesize - 1));

	buf = ops->datbuf;
	oob = ops->oobbuf;

	while(1) {
		bytes = min(mtd->writesize - col, readlen);
		aligned = (bytes == mtd->writesize);

		/* Is the current page in the buffer ? */
		if (realpage != chip->pagebuf || oob) {
			bufpoi = aligned ? buf : chip->buffers->databuf;

			if (likely(sndcmd)) {
				chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
				sndcmd = 0;
			}

			/* Now read the page into the buffer */
			if (unlikely(ops->mode == MTD_OOB_RAW))
				ret = chip->ecc.read_page_raw(mtd, chip,
							      bufpoi, page);
			else if (!aligned && NAND_SUBPAGE_READ(chip) && !oob)
				ret = chip->ecc.read_subpage(mtd, chip, col, bytes, bufpoi);
			else
				ret = chip->ecc.read_page(mtd, chip, bufpoi,
							  page);
			if (ret < 0)
				break;

			/* Transfer not aligned data */
			if (!aligned) {
				if (!NAND_SUBPAGE_READ(chip) && !oob)
					chip->pagebuf = realpage;
				memcpy(buf, chip->buffers->databuf + col, bytes);
			}

			buf += bytes;

			if (unlikely(oob)) {
				/* Raw mode does data:oob:data:oob */
				if (ops->mode != MTD_OOB_RAW) {
					int toread = min(oobreadlen,
						chip->ecc.layout->oobavail);
					if (toread) {
						oob = nand_transfer_oob(chip,
							oob, ops, toread);
						oobreadlen -= toread;
					}
				} else
					buf = nand_transfer_oob(chip,
						buf, ops, mtd->oobsize);
			}

			if (!(chip->options & NAND_NO_READRDY)) {
				/*
				 * Apply delay or wait for ready/busy pin. Do
				 * this before the AUTOINCR check, so no
				 * problems arise if a chip which does auto
				 * increment is marked as NOAUTOINCR by the
				 * board driver.
				 */
				if (!chip->dev_ready)
					udelay(chip->chip_delay);
				else
					nand_wait_ready(mtd);
			}
		} else {
			memcpy(buf, chip->buffers->databuf + col, bytes);
			buf += bytes;
		}

		readlen -= bytes;

		if (!readlen)
			break;

		/* For subsequent reads align to page boundary. */
		col = 0;
		/* Increment page address */
		realpage++;

		page = realpage & chip->pagemask;
		/* Check, if we cross a chip boundary */
		if (!page) {
			chipnr++;
			chip->select_chip(mtd, -1);
			chip->select_chip(mtd, chipnr);
		}

		/* Check, if the chip supports auto page increment
		 * or if we have hit a block boundary.
		 */
		if (!NAND_CANAUTOINCR(chip) || !(page & blkcheck))
			sndcmd = 1;
	}

	ops->retlen = ops->len - (size_t) readlen;
	if (oob)
		ops->oobretlen = ops->ooblen - oobreadlen;

	if (ret)
		return ret;

	if (mtd->ecc_stats.failed - stats.failed)
		return -EBADMSG;

	return  mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
}

/**
 * nand_read - [MTD Interface] MTD compability function for nand_do_read_ecc
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @retlen:	pointer to variable to store the number of read bytes
 * @buf:	the databuffer to put data
 *
 * Get hold of the chip and call nand_do_read
 */
static int nand_read(struct mtd_info *mtd, loff_t from, size_t len,
		     size_t *retlen, uint8_t *buf)
{
	struct nand_chip *chip = mtd->priv;
	int ret;

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size)
		return -EINVAL;
	if (!len)
		return 0;

	nand_get_device(chip, mtd, FL_READING);

	chip->ops.len = len;
	chip->ops.datbuf = buf;
	chip->ops.oobbuf = NULL;

	ret = nand_do_read_ops(mtd, from, &chip->ops);

	*retlen = chip->ops.retlen;

	nand_release_device(mtd);

	return ret;
}

/**
 * nand_read_oob_std - [REPLACABLE] the most common OOB data read function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @page:	page number to read
 * @sndcmd:	flag whether to issue read command or not
 */
static int nand_read_oob_std(struct mtd_info *mtd, struct nand_chip *chip,
			     int page, int sndcmd)
{
	if (sndcmd) {
		chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
		sndcmd = 0;
	}
	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
	return sndcmd;
}

/**
 * nand_read_oob_syndrome - [REPLACABLE] OOB data read function for HW ECC
 *			    with syndromes
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @page:	page number to read
 * @sndcmd:	flag whether to issue read command or not
 */
static int nand_read_oob_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
				  int page, int sndcmd)
{
	uint8_t *buf = chip->oob_poi;
	int length = mtd->oobsize;
	int chunk = chip->ecc.bytes + chip->ecc.prepad + chip->ecc.postpad;
	int eccsize = chip->ecc.size;
	uint8_t *bufpoi = buf;
	int i, toread, sndrnd = 0, pos;

	chip->cmdfunc(mtd, NAND_CMD_READ0, chip->ecc.size, page);
	for (i = 0; i < chip->ecc.steps; i++) {
		if (sndrnd) {
			pos = eccsize + i * (eccsize + chunk);
			if (mtd->writesize > 512)
				chip->cmdfunc(mtd, NAND_CMD_RNDOUT, pos, -1);
			else
				chip->cmdfunc(mtd, NAND_CMD_READ0, pos, page);
		} else
			sndrnd = 1;
		toread = min_t(int, length, chunk);
		chip->read_buf(mtd, bufpoi, toread);
		bufpoi += toread;
		length -= toread;
	}
	if (length > 0)
		chip->read_buf(mtd, bufpoi, length);

	return 1;
}

/**
 * nand_write_oob_std - [REPLACABLE] the most common OOB data write function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @page:	page number to write
 */
static int nand_write_oob_std(struct mtd_info *mtd, struct nand_chip *chip,
			      int page)
{
	int status = 0;
	const uint8_t *buf = chip->oob_poi;
	int length = mtd->oobsize;

	chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page);
	chip->write_buf(mtd, buf, length);
	/* Send command to program the OOB data */
	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);

	status = chip->waitfunc(mtd, chip);

	return status & NAND_STATUS_FAIL ? -EIO : 0;
}

/**
 * nand_write_oob_syndrome - [REPLACABLE] OOB data write function for HW ECC
 *			     with syndrome - only for large page flash !
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @page:	page number to write
 */
static int nand_write_oob_syndrome(struct mtd_info *mtd,
				   struct nand_chip *chip, int page)
{
	int chunk = chip->ecc.bytes + chip->ecc.prepad + chip->ecc.postpad;
	int eccsize = chip->ecc.size, length = mtd->oobsize;
	int i, len, pos, status = 0, sndcmd = 0, steps = chip->ecc.steps;
	const uint8_t *bufpoi = chip->oob_poi;

	/*
	 * data-ecc-data-ecc ... ecc-oob
	 * or
	 * data-pad-ecc-pad-data-pad .... ecc-pad-oob
	 */
	if (!chip->ecc.prepad && !chip->ecc.postpad) {
		pos = steps * (eccsize + chunk);
		steps = 0;
	} else
		pos = eccsize;

	chip->cmdfunc(mtd, NAND_CMD_SEQIN, pos, page);
	for (i = 0; i < steps; i++) {
		if (sndcmd) {
			if (mtd->writesize <= 512) {
				uint32_t fill = 0xFFFFFFFF;

				len = eccsize;
				while (len > 0) {
					int num = min_t(int, len, 4);
					chip->write_buf(mtd, (uint8_t *)&fill,
							num);
					len -= num;
				}
			} else {
				pos = eccsize + i * (eccsize + chunk);
				chip->cmdfunc(mtd, NAND_CMD_RNDIN, pos, -1);
			}
		} else
			sndcmd = 1;
		len = min_t(int, length, chunk);
		chip->write_buf(mtd, bufpoi, len);
		bufpoi += len;
		length -= len;
	}
	if (length > 0)
		chip->write_buf(mtd, bufpoi, length);

	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
	status = chip->waitfunc(mtd, chip);

	return status & NAND_STATUS_FAIL ? -EIO : 0;
}

/**
 * nand_do_read_oob - [Intern] NAND read out-of-band
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @ops:	oob operations description structure
 *
 * NAND read out-of-band data from the spare area
 */
static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
			    struct mtd_oob_ops *ops)
{
	int page, realpage, chipnr, sndcmd = 1;
	struct nand_chip *chip = mtd->priv;
	int blkcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;
	int readlen = ops->ooblen;
	int len;
	uint8_t *buf = ops->oobbuf;

	DEBUG(MTD_DEBUG_LEVEL3, "%s: from = 0x%08Lx, len = %i\n",
			__func__, (unsigned long long)from, readlen);

	if (ops->mode == MTD_OOB_AUTO)
		len = chip->ecc.layout->oobavail;
	else
		len = mtd->oobsize;

	if (unlikely(ops->ooboffs >= len)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt to start read "
					"outside oob\n", __func__);
		return -EINVAL;
	}

	/* Do not allow reads past end of device */
	if (unlikely(from >= mtd->size ||
		     ops->ooboffs + readlen > ((mtd->size >> chip->page_shift) -
					(from >> chip->page_shift)) * len)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt read beyond end "
					"of device\n", __func__);
		return -EINVAL;
	}

	chipnr = (int)(from >> chip->chip_shift);
	chip->select_chip(mtd, chipnr);

	/* Shift to get page */
	realpage = (int)(from >> chip->page_shift);
	page = realpage & chip->pagemask;

	while(1) {
		sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);

		len = min(len, readlen);
		buf = nand_transfer_oob(chip, buf, ops, len);

		if (!(chip->options & NAND_NO_READRDY)) {
			/*
			 * Apply delay or wait for ready/busy pin. Do this
			 * before the AUTOINCR check, so no problems arise if a
			 * chip which does auto increment is marked as
			 * NOAUTOINCR by the board driver.
			 */
			if (!chip->dev_ready)
				udelay(chip->chip_delay);
			else
				nand_wait_ready(mtd);
		}

		readlen -= len;
		if (!readlen)
			break;

		/* Increment page address */
		realpage++;

		page = realpage & chip->pagemask;
		/* Check, if we cross a chip boundary */
		if (!page) {
			chipnr++;
			chip->select_chip(mtd, -1);
			chip->select_chip(mtd, chipnr);
		}

		/* Check, if the chip supports auto page increment
		 * or if we have hit a block boundary.
		 */
		if (!NAND_CANAUTOINCR(chip) || !(page & blkcheck))
			sndcmd = 1;
	}

	ops->oobretlen = ops->ooblen;
	return 0;
}

/**
 * nand_read_oob - [MTD Interface] NAND read data and/or out-of-band
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @ops:	oob operation description structure
 *
 * NAND read data and/or out-of-band data
 */
static int nand_read_oob(struct mtd_info *mtd, loff_t from,
			 struct mtd_oob_ops *ops)
{
	struct nand_chip *chip = mtd->priv;
	int ret = -ENOTSUPP;

	ops->retlen = 0;

	/* Do not allow reads past end of device */
	if (ops->datbuf && (from + ops->len) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt read "
				"beyond end of device\n", __func__);
		return -EINVAL;
	}

	nand_get_device(chip, mtd, FL_READING);

	switch(ops->mode) {
	case MTD_OOB_PLACE:
	case MTD_OOB_AUTO:
	case MTD_OOB_RAW:
		break;

	default:
		goto out;
	}

	if (!ops->datbuf)
		ret = nand_do_read_oob(mtd, from, ops);
	else
		ret = nand_do_read_ops(mtd, from, ops);

 out:
	nand_release_device(mtd);
	return ret;
}


/**
 * nand_write_page_raw - [Intern] raw page write function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	data buffer
 *
 * Not for syndrome calculating ecc controllers, which use a special oob layout
 */
static void nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
				const uint8_t *buf)
{
	chip->write_buf(mtd, buf, mtd->writesize);
	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
}

/**
 * nand_write_page_raw_syndrome - [Intern] raw page write function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	data buffer
 *
 * We need a special oob layout and handling even when ECC isn't checked.
 */
static void nand_write_page_raw_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
				const uint8_t *buf)
{
	int eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	uint8_t *oob = chip->oob_poi;
	int steps, size;

	for (steps = chip->ecc.steps; steps > 0; steps--) {
		chip->write_buf(mtd, buf, eccsize);
		buf += eccsize;

		if (chip->ecc.prepad) {
			chip->write_buf(mtd, oob, chip->ecc.prepad);
			oob += chip->ecc.prepad;
		}

		chip->read_buf(mtd, oob, eccbytes);
		oob += eccbytes;

		if (chip->ecc.postpad) {
			chip->write_buf(mtd, oob, chip->ecc.postpad);
			oob += chip->ecc.postpad;
		}
	}

	size = mtd->oobsize - (oob - chip->oob_poi);
	if (size)
		chip->write_buf(mtd, oob, size);
}
/**
 * nand_write_page_swecc - [REPLACABLE] software ecc based page write function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	data buffer
 */
static void nand_write_page_swecc(struct mtd_info *mtd, struct nand_chip *chip,
				  const uint8_t *buf)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *ecc_calc = chip->buffers->ecccalc;
	const uint8_t *p = buf;
	uint32_t *eccpos = chip->ecc.layout->eccpos;

	/* Software ecc calculation */
	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);

	for (i = 0; i < chip->ecc.total; i++)
		chip->oob_poi[eccpos[i]] = ecc_calc[i];

	chip->ecc.write_page_raw(mtd, chip, buf);
}

/**
 * nand_write_page_hwecc - [REPLACABLE] hardware ecc based page write function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	data buffer
 */
static void nand_write_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
				  const uint8_t *buf)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *ecc_calc = chip->buffers->ecccalc;
	const uint8_t *p = buf;
	uint32_t *eccpos = chip->ecc.layout->eccpos;

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		chip->ecc.hwctl(mtd, NAND_ECC_WRITE);
		chip->write_buf(mtd, p, eccsize);
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
	}

	for (i = 0; i < chip->ecc.total; i++)
		chip->oob_poi[eccpos[i]] = ecc_calc[i];

	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
}

/**
 * nand_write_page_syndrome - [REPLACABLE] hardware ecc syndrom based page write
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	data buffer
 *
 * The hw generator calculates the error syndrome automatically. Therefor
 * we need a special oob layout and handling.
 */
static void nand_write_page_syndrome(struct mtd_info *mtd,
				    struct nand_chip *chip, const uint8_t *buf)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	const uint8_t *p = buf;
	uint8_t *oob = chip->oob_poi;

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {

		chip->ecc.hwctl(mtd, NAND_ECC_WRITE);
		chip->write_buf(mtd, p, eccsize);

		if (chip->ecc.prepad) {
			chip->write_buf(mtd, oob, chip->ecc.prepad);
			oob += chip->ecc.prepad;
		}

		chip->ecc.calculate(mtd, p, oob);
		chip->write_buf(mtd, oob, eccbytes);
		oob += eccbytes;

		if (chip->ecc.postpad) {
			chip->write_buf(mtd, oob, chip->ecc.postpad);
			oob += chip->ecc.postpad;
		}
	}

	/* Calculate remaining oob bytes */
	i = mtd->oobsize - (oob - chip->oob_poi);
	if (i)
		chip->write_buf(mtd, oob, i);
}

/**
 * nand_write_page - [REPLACEABLE] write one page
 * @mtd:	MTD device structure
 * @chip:	NAND chip descriptor
 * @buf:	the data to write
 * @page:	page number to write
 * @cached:	cached programming
 * @raw:	use _raw version of write_page
 */
static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
			   const uint8_t *buf, int page, int cached, int raw)
{
	int status;

	chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);

	if (unlikely(raw))
		chip->ecc.write_page_raw(mtd, chip, buf);
	else
		chip->ecc.write_page(mtd, chip, buf);

	/*
	 * Cached progamming disabled for now, Not sure if its worth the
	 * trouble. The speed gain is not very impressive. (2.3->2.6Mib/s)
	 */
	cached = 0;

	if (!cached || !(chip->options & NAND_CACHEPRG)) {

		chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
		status = chip->waitfunc(mtd, chip);
		/*
		 * See if operation failed and additional status checks are
		 * available
		 */
		if ((status & NAND_STATUS_FAIL) && (chip->errstat))
			status = chip->errstat(mtd, chip, FL_WRITING, status,
					       page);

		if (status & NAND_STATUS_FAIL)
			return -EIO;
	} else {
		chip->cmdfunc(mtd, NAND_CMD_CACHEDPROG, -1, -1);
		status = chip->waitfunc(mtd, chip);
	}

#ifdef CONFIG_MTD_NAND_VERIFY_WRITE
	/* Send command to read back the data */
	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);

	if (chip->verify_buf(mtd, buf, mtd->writesize))
		return -EIO;
#endif
	return 0;
}

/**
 * nand_fill_oob - [Internal] Transfer client buffer to oob
 * @chip:	nand chip structure
 * @oob:	oob data buffer
 * @ops:	oob ops structure
 */
static uint8_t *nand_fill_oob(struct nand_chip *chip, uint8_t *oob,
				  struct mtd_oob_ops *ops)
{
	size_t len = ops->ooblen;

	switch(ops->mode) {

	case MTD_OOB_PLACE:
	case MTD_OOB_RAW:
		memcpy(chip->oob_poi + ops->ooboffs, oob, len);
		return oob + len;

	case MTD_OOB_AUTO: {
		struct nand_oobfree *free = chip->ecc.layout->oobfree;
		uint32_t boffs = 0, woffs = ops->ooboffs;
		size_t bytes = 0;

		for(; free->length && len; free++, len -= bytes) {
			/* Write request not from offset 0 ? */
			if (unlikely(woffs)) {
				if (woffs >= free->length) {
					woffs -= free->length;
					continue;
				}
				boffs = free->offset + woffs;
				bytes = min_t(size_t, len,
					      (free->length - woffs));
				woffs = 0;
			} else {
				bytes = min_t(size_t, len, free->length);
				boffs = free->offset;
			}
			memcpy(chip->oob_poi + boffs, oob, bytes);
			oob += bytes;
		}
		return oob;
	}
	default:
		BUG();
	}
	return NULL;
}

#define NOTALIGNED(x)	(x & (chip->subpagesize - 1)) != 0

/**
 * nand_do_write_ops - [Internal] NAND write with ECC
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @ops:	oob operations description structure
 *
 * NAND write with ECC
 */
static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
			     struct mtd_oob_ops *ops)
{
	int chipnr, realpage, page, blockmask, column;
	struct nand_chip *chip = mtd->priv;
	uint32_t writelen = ops->len;
	uint8_t *oob = ops->oobbuf;
	uint8_t *buf = ops->datbuf;
	int ret, subpage;

	ops->retlen = 0;
	if (!writelen)
		return 0;

	/* reject writes, which are not page aligned */
	if (NOTALIGNED(to) || NOTALIGNED(ops->len)) {
		printk(KERN_NOTICE "%s: Attempt to write not "
				"page aligned data\n", __func__);
		return -EINVAL;
	}

	column = to & (mtd->writesize - 1);
	subpage = column || (writelen & (mtd->writesize - 1));

	if (subpage && oob)
		return -EINVAL;

	chipnr = (int)(to >> chip->chip_shift);
	chip->select_chip(mtd, chipnr);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		return -EIO;

	realpage = (int)(to >> chip->page_shift);
	page = realpage & chip->pagemask;
	blockmask = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;

	/* Invalidate the page cache, when we write to the cached page */
	if (to <= (chip->pagebuf << chip->page_shift) &&
	    (chip->pagebuf << chip->page_shift) < (to + ops->len))
		chip->pagebuf = -1;

	/* If we're not given explicit OOB data, let it be 0xFF */
	if (likely(!oob))
		memset(chip->oob_poi, 0xff, mtd->oobsize);

	while(1) {
		int bytes = mtd->writesize;
		int cached = writelen > bytes && page != blockmask;
		uint8_t *wbuf = buf;

		/* Partial page write ? */
		if (unlikely(column || writelen < (mtd->writesize - 1))) {
			cached = 0;
			bytes = min_t(int, bytes - column, (int) writelen);
			chip->pagebuf = -1;
			memset(chip->buffers->databuf, 0xff, mtd->writesize);
			memcpy(&chip->buffers->databuf[column], buf, bytes);
			wbuf = chip->buffers->databuf;
		}

		if (unlikely(oob))
			oob = nand_fill_oob(chip, oob, ops);

		ret = chip->write_page(mtd, chip, wbuf, page, cached,
				       (ops->mode == MTD_OOB_RAW));
		if (ret)
			break;

		writelen -= bytes;
		if (!writelen)
			break;

		column = 0;
		buf += bytes;
		realpage++;

		page = realpage & chip->pagemask;
		/* Check, if we cross a chip boundary */
		if (!page) {
			chipnr++;
			chip->select_chip(mtd, -1);
			chip->select_chip(mtd, chipnr);
		}
	}

	ops->retlen = ops->len - writelen;
	if (unlikely(oob))
		ops->oobretlen = ops->ooblen;
	return ret;
}

/**
 * nand_write - [MTD Interface] NAND write with ECC
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @len:	number of bytes to write
 * @retlen:	pointer to variable to store the number of written bytes
 * @buf:	the data to write
 *
 * NAND write with ECC
 */
static int nand_write(struct mtd_info *mtd, loff_t to, size_t len,
			  size_t *retlen, const uint8_t *buf)
{
	struct nand_chip *chip = mtd->priv;
	int ret;

	/* Do not allow reads past end of device */
	if ((to + len) > mtd->size)
		return -EINVAL;
	if (!len)
		return 0;

	nand_get_device(chip, mtd, FL_WRITING);

	chip->ops.len = len;
	chip->ops.datbuf = (uint8_t *)buf;
	chip->ops.oobbuf = NULL;

	ret = nand_do_write_ops(mtd, to, &chip->ops);

	*retlen = chip->ops.retlen;

	nand_release_device(mtd);

	return ret;
}

/**
 * nand_do_write_oob - [MTD Interface] NAND write out-of-band
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @ops:	oob operation description structure
 *
 * NAND write out-of-band
 */
static int nand_do_write_oob(struct mtd_info *mtd, loff_t to,
			     struct mtd_oob_ops *ops)
{
	int chipnr, page, status, len;
	struct nand_chip *chip = mtd->priv;

	DEBUG(MTD_DEBUG_LEVEL3, "%s: to = 0x%08x, len = %i\n",
			 __func__, (unsigned int)to, (int)ops->ooblen);

	if (ops->mode == MTD_OOB_AUTO)
		len = chip->ecc.layout->oobavail;
	else
		len = mtd->oobsize;

	/* Do not allow write past end of page */
	if ((ops->ooboffs + ops->ooblen) > len) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt to write "
				"past end of page\n", __func__);
		return -EINVAL;
	}

	if (unlikely(ops->ooboffs >= len)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt to start "
				"write outside oob\n", __func__);
		return -EINVAL;
	}

	/* Do not allow reads past end of device */
	if (unlikely(to >= mtd->size ||
		     ops->ooboffs + ops->ooblen >
			((mtd->size >> chip->page_shift) -
			 (to >> chip->page_shift)) * len)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt write beyond "
				"end of device\n", __func__);
		return -EINVAL;
	}

	chipnr = (int)(to >> chip->chip_shift);
	chip->select_chip(mtd, chipnr);

	/* Shift to get page */
	page = (int)(to >> chip->page_shift);

	/*
	 * Reset the chip. Some chips (like the Toshiba TC5832DC found in one
	 * of my DiskOnChip 2000 test units) will clear the whole data page too
	 * if we don't do this. I have no clue why, but I seem to have 'fixed'
	 * it in the doc2000 driver in August 1999.  dwmw2.
	 */
	chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		return -EROFS;

	/* Invalidate the page cache, if we write to the cached page */
	if (page == chip->pagebuf)
		chip->pagebuf = -1;

	memset(chip->oob_poi, 0xff, mtd->oobsize);
	nand_fill_oob(chip, ops->oobbuf, ops);
	status = chip->ecc.write_oob(mtd, chip, page & chip->pagemask);
	memset(chip->oob_poi, 0xff, mtd->oobsize);

	if (status)
		return status;

	ops->oobretlen = ops->ooblen;

	return 0;
}

/**
 * nand_write_oob - [MTD Interface] NAND write data and/or out-of-band
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @ops:	oob operation description structure
 */
static int nand_write_oob(struct mtd_info *mtd, loff_t to,
			  struct mtd_oob_ops *ops)
{
	struct nand_chip *chip = mtd->priv;
	int ret = -ENOTSUPP;

	ops->retlen = 0;

	/* Do not allow writes past end of device */
	if (ops->datbuf && (to + ops->len) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt write beyond "
				"end of device\n", __func__);
		return -EINVAL;
	}

	nand_get_device(chip, mtd, FL_WRITING);

	switch(ops->mode) {
	case MTD_OOB_PLACE:
	case MTD_OOB_AUTO:
	case MTD_OOB_RAW:
		break;

	default:
		goto out;
	}

	if (!ops->datbuf)
		ret = nand_do_write_oob(mtd, to, ops);
	else
		ret = nand_do_write_ops(mtd, to, ops);

 out:
	nand_release_device(mtd);
	return ret;
}

/**
 * single_erease_cmd - [GENERIC] NAND standard block erase command function
 * @mtd:	MTD device structure
 * @page:	the page address of the block which will be erased
 *
 * Standard erase command for NAND chips
 */
static void single_erase_cmd(struct mtd_info *mtd, int page)
{
	struct nand_chip *chip = mtd->priv;
	/* Send commands to erase a block */
	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page);
	chip->cmdfunc(mtd, NAND_CMD_ERASE2, -1, -1);
}

/**
 * multi_erease_cmd - [GENERIC] AND specific block erase command function
 * @mtd:	MTD device structure
 * @page:	the page address of the block which will be erased
 *
 * AND multi block erase command function
 * Erase 4 consecutive blocks
 */
static void multi_erase_cmd(struct mtd_info *mtd, int page)
{
	struct nand_chip *chip = mtd->priv;
	/* Send commands to erase a block */
	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page++);
	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page++);
	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page++);
	chip->cmdfunc(mtd, NAND_CMD_ERASE1, -1, page);
	chip->cmdfunc(mtd, NAND_CMD_ERASE2, -1, -1);
}

/**
 * nand_erase - [MTD Interface] erase block(s)
 * @mtd:	MTD device structure
 * @instr:	erase instruction
 *
 * Erase one ore more blocks
 */
static int nand_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	return nand_erase_nand(mtd, instr, 0);
}

#define BBT_PAGE_MASK	0xffffff3f
/**
 * nand_erase_nand - [Internal] erase block(s)
 * @mtd:	MTD device structure
 * @instr:	erase instruction
 * @allowbbt:	allow erasing the bbt area
 *
 * Erase one ore more blocks
 */
int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
		    int allowbbt)
{
	int page, status, pages_per_block, ret, chipnr;
	struct nand_chip *chip = mtd->priv;
	loff_t rewrite_bbt[NAND_MAX_CHIPS]={0};
	unsigned int bbt_masked_page = 0xffffffff;
	loff_t len;

	DEBUG(MTD_DEBUG_LEVEL3, "%s: start = 0x%012llx, len = %llu\n",
				__func__, (unsigned long long)instr->addr,
				(unsigned long long)instr->len);

	/* Start address must align on block boundary */
	if (instr->addr & ((1 << chip->phys_erase_shift) - 1)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Unaligned address\n", __func__);
		return -EINVAL;
	}

	/* Length must align on block boundary */
	if (instr->len & ((1 << chip->phys_erase_shift) - 1)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Length not block aligned\n",
					__func__);
		return -EINVAL;
	}

	/* Do not allow erase past end of device */
	if ((instr->len + instr->addr) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Erase past end of device\n",
					__func__);
		return -EINVAL;
	}

	instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;

	/* Grab the lock and see if the device is available */
	nand_get_device(chip, mtd, FL_ERASING);

	/* Shift to get first page */
	page = (int)(instr->addr >> chip->page_shift);
	chipnr = (int)(instr->addr >> chip->chip_shift);

	/* Calculate pages in each block */
	pages_per_block = 1 << (chip->phys_erase_shift - chip->page_shift);

	/* Select the NAND device */
	chip->select_chip(mtd, chipnr);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd)) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: Device is write protected!!!\n",
					__func__);
		instr->state = MTD_ERASE_FAILED;
		goto erase_exit;
	}

	/*
	 * If BBT requires refresh, set the BBT page mask to see if the BBT
	 * should be rewritten. Otherwise the mask is set to 0xffffffff which
	 * can not be matched. This is also done when the bbt is actually
	 * erased to avoid recusrsive updates
	 */
	if (chip->options & BBT_AUTO_REFRESH && !allowbbt)
		bbt_masked_page = chip->bbt_td->pages[chipnr] & BBT_PAGE_MASK;

	/* Loop through the pages */
	len = instr->len;

	instr->state = MTD_ERASING;

	while (len) {
		/*
		 * heck if we have a bad block, we do not erase bad blocks !
		 */
		if (nand_block_checkbad(mtd, ((loff_t) page) <<
					chip->page_shift, 0, allowbbt)) {
			printk(KERN_WARNING "%s: attempt to erase a bad block "
					"at page 0x%08x\n", __func__, page);
			instr->state = MTD_ERASE_FAILED;
			goto erase_exit;
		}

		/*
		 * Invalidate the page cache, if we erase the block which
		 * contains the current cached page
		 */
		if (page <= chip->pagebuf && chip->pagebuf <
		    (page + pages_per_block))
			chip->pagebuf = -1;

		chip->erase_cmd(mtd, page & chip->pagemask);

		status = chip->waitfunc(mtd, chip);

		/*
		 * See if operation failed and additional status checks are
		 * available
		 */
		if ((status & NAND_STATUS_FAIL) && (chip->errstat))
			status = chip->errstat(mtd, chip, FL_ERASING,
					       status, page);

		/* See if block erase succeeded */
		if (status & NAND_STATUS_FAIL) {
			DEBUG(MTD_DEBUG_LEVEL0, "%s: Failed erase, "
					"page 0x%08x\n", __func__, page);
			instr->state = MTD_ERASE_FAILED;
			instr->fail_addr =
				((loff_t)page << chip->page_shift);
			goto erase_exit;
		}

		/*
		 * If BBT requires refresh, set the BBT rewrite flag to the
		 * page being erased
		 */
		if (bbt_masked_page != 0xffffffff &&
		    (page & BBT_PAGE_MASK) == bbt_masked_page)
			    rewrite_bbt[chipnr] =
					((loff_t)page << chip->page_shift);

		/* Increment page address and decrement length */
		len -= (1 << chip->phys_erase_shift);
		page += pages_per_block;

		/* Check, if we cross a chip boundary */
		if (len && !(page & chip->pagemask)) {
			chipnr++;
			chip->select_chip(mtd, -1);
			chip->select_chip(mtd, chipnr);

			/*
			 * If BBT requires refresh and BBT-PERCHIP, set the BBT
			 * page mask to see if this BBT should be rewritten
			 */
			if (bbt_masked_page != 0xffffffff &&
			    (chip->bbt_td->options & NAND_BBT_PERCHIP))
				bbt_masked_page = chip->bbt_td->pages[chipnr] &
					BBT_PAGE_MASK;
		}
	}
	instr->state = MTD_ERASE_DONE;

 erase_exit:

	ret = instr->state == MTD_ERASE_DONE ? 0 : -EIO;

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	/* Do call back function */
	if (!ret)
		mtd_erase_callback(instr);

	/*
	 * If BBT requires refresh and erase was successful, rewrite any
	 * selected bad block tables
	 */
	if (bbt_masked_page == 0xffffffff || ret)
		return ret;

	for (chipnr = 0; chipnr < chip->numchips; chipnr++) {
		if (!rewrite_bbt[chipnr])
			continue;
		/* update the BBT for chip */
		DEBUG(MTD_DEBUG_LEVEL0, "%s: nand_update_bbt "
			"(%d:0x%0llx 0x%0x)\n", __func__, chipnr,
			rewrite_bbt[chipnr], chip->bbt_td->pages[chipnr]);
		nand_update_bbt(mtd, rewrite_bbt[chipnr]);
	}

	/* Return more or less happy */
	return ret;
}

/**
 * nand_sync - [MTD Interface] sync
 * @mtd:	MTD device structure
 *
 * Sync is actually a wait for chip ready function
 */
static void nand_sync(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;

	DEBUG(MTD_DEBUG_LEVEL3, "%s: called\n", __func__);

	/* Grab the lock and see if the device is available */
	nand_get_device(chip, mtd, FL_SYNCING);
	/* Release it and go back */
	nand_release_device(mtd);
}

/**
 * nand_block_isbad - [MTD Interface] Check if block at offset is bad
 * @mtd:	MTD device structure
 * @offs:	offset relative to mtd start
 */
static int nand_block_isbad(struct mtd_info *mtd, loff_t offs)
{
	/* Check for invalid offset */
	if (offs > mtd->size)
		return -EINVAL;

	return nand_block_checkbad(mtd, offs, 1, 0);
}

/**
 * nand_block_markbad - [MTD Interface] Mark block at the given offset as bad
 * @mtd:	MTD device structure
 * @ofs:	offset relative to mtd start
 */
static int nand_block_markbad(struct mtd_info *mtd, loff_t ofs)
{
	struct nand_chip *chip = mtd->priv;
	int ret;

	if ((ret = nand_block_isbad(mtd, ofs))) {
		/* If it was bad already, return success and do nothing. */
		if (ret > 0)
			return 0;
		return ret;
	}

	return chip->block_markbad(mtd, ofs);
}

/**
 * nand_suspend - [MTD Interface] Suspend the NAND flash
 * @mtd:	MTD device structure
 */
static int nand_suspend(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;

	return nand_get_device(chip, mtd, FL_PM_SUSPENDED);
}

/**
 * nand_resume - [MTD Interface] Resume the NAND flash
 * @mtd:	MTD device structure
 */
static void nand_resume(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;

	if (chip->state == FL_PM_SUSPENDED)
		nand_release_device(mtd);
	else
		printk(KERN_ERR "%s called for a chip which is not "
		       "in suspended state\n", __func__);
}

/*
 * Set default functions
 */
static void nand_set_defaults(struct nand_chip *chip, int busw)
{
	/* check for proper chip_delay setup, set 20us if not */
	if (!chip->chip_delay)
		chip->chip_delay = 20;

	/* check, if a user supplied command function given */
	if (chip->cmdfunc == NULL)
		chip->cmdfunc = nand_command;

	/* check, if a user supplied wait function given */
	if (chip->waitfunc == NULL)
		chip->waitfunc = nand_wait;

	if (!chip->select_chip)
		chip->select_chip = nand_select_chip;
	if (!chip->read_byte)
		chip->read_byte = busw ? nand_read_byte16 : nand_read_byte;
	if (!chip->read_word)
		chip->read_word = nand_read_word;
	if (!chip->block_bad)
		chip->block_bad = nand_block_bad;
	if (!chip->block_markbad)
		chip->block_markbad = nand_default_block_markbad;
	if (!chip->write_buf)
		chip->write_buf = busw ? nand_write_buf16 : nand_write_buf;
	if (!chip->read_buf)
		chip->read_buf = busw ? nand_read_buf16 : nand_read_buf;
	if (!chip->verify_buf)
		chip->verify_buf = busw ? nand_verify_buf16 : nand_verify_buf;
	if (!chip->scan_bbt)
		chip->scan_bbt = nand_default_bbt;

	if (!chip->controller) {
		chip->controller = &chip->hwcontrol;
		spin_lock_init(&chip->controller->lock);
		init_waitqueue_head(&chip->controller->wq);
	}

}

/*
 * Get the flash and manufacturer id and lookup if the type is supported
 */
static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
						  struct nand_chip *chip,
						  int busw, int *maf_id)
{
	struct nand_flash_dev *type = NULL;
	int i, dev_id, maf_idx;
	int tmp_id, tmp_manf;

	/* Select the device */
	chip->select_chip(mtd, 0);

	/*
	 * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx)
	 * after power-up
	 */
	chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);

	/* Send the command for reading device ID */
	chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);

	/* Read manufacturer and device IDs */
	*maf_id = chip->read_byte(mtd);
	dev_id = chip->read_byte(mtd);

	/* Try again to make sure, as some systems the bus-hold or other
	 * interface concerns can cause random data which looks like a
	 * possibly credible NAND flash to appear. If the two results do
	 * not match, ignore the device completely.
	 */

	chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);

	/* Read manufacturer and device IDs */

	tmp_manf = chip->read_byte(mtd);
	tmp_id = chip->read_byte(mtd);

	if (tmp_manf != *maf_id || tmp_id != dev_id) {
		printk(KERN_INFO "%s: second ID read did not match "
		       "%02x,%02x against %02x,%02x\n", __func__,
		       *maf_id, dev_id, tmp_manf, tmp_id);
		return ERR_PTR(-ENODEV);
	}

	/* Lookup the flash id */
	for (i = 0; nand_flash_ids[i].name != NULL; i++) {
		if (dev_id == nand_flash_ids[i].id) {
			type =  &nand_flash_ids[i];
			break;
		}
	}

	if (!type)
		return ERR_PTR(-ENODEV);

	if (!mtd->name)
		mtd->name = type->name;

	chip->chipsize = (uint64_t)type->chipsize << 20;

	/* Newer devices have all the information in additional id bytes */
	if (!type->pagesize) {
		int extid;
		/* The 3rd id byte holds MLC / multichip data */
		chip->cellinfo = chip->read_byte(mtd);
		/* The 4th id byte is the important one */
		extid = chip->read_byte(mtd);
		/* Calc pagesize */
		mtd->writesize = 1024 << (extid & 0x3);
		extid >>= 2;
		/* Calc oobsize */
		mtd->oobsize = (8 << (extid & 0x01)) * (mtd->writesize >> 9);
		extid >>= 2;
		/* Calc blocksize. Blocksize is multiples of 64KiB */
		mtd->erasesize = (64 * 1024) << (extid & 0x03);
		extid >>= 2;
		/* Get buswidth information */
		busw = (extid & 0x01) ? NAND_BUSWIDTH_16 : 0;

	} else {
		/*
		 * Old devices have chip data hardcoded in the device id table
		 */
		mtd->erasesize = type->erasesize;
		mtd->writesize = type->pagesize;
		mtd->oobsize = mtd->writesize / 32;
		busw = type->options & NAND_BUSWIDTH_16;
	}

	/* Try to identify manufacturer */
	for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_idx++) {
		if (nand_manuf_ids[maf_idx].id == *maf_id)
			break;
	}

	/*
	 * Check, if buswidth is correct. Hardware drivers should set
	 * chip correct !
	 */
	if (busw != (chip->options & NAND_BUSWIDTH_16)) {
		printk(KERN_INFO "NAND device: Manufacturer ID:"
		       " 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,
		       dev_id, nand_manuf_ids[maf_idx].name, mtd->name);
		printk(KERN_WARNING "NAND bus width %d instead %d bit\n",
		       (chip->options & NAND_BUSWIDTH_16) ? 16 : 8,
		       busw ? 16 : 8);
		return ERR_PTR(-EINVAL);
	}

	/* Calculate the address shift from the page size */
	chip->page_shift = ffs(mtd->writesize) - 1;
	/* Convert chipsize to number of pages per chip -1. */
	chip->pagemask = (chip->chipsize >> chip->page_shift) - 1;

	chip->bbt_erase_shift = chip->phys_erase_shift =
		ffs(mtd->erasesize) - 1;
	if (chip->chipsize & 0xffffffff)
		chip->chip_shift = ffs((unsigned)chip->chipsize) - 1;
	else
		chip->chip_shift = ffs((unsigned)(chip->chipsize >> 32)) + 32 - 1;

	/* Set the bad block position */
	chip->badblockpos = mtd->writesize > 512 ?
		NAND_LARGE_BADBLOCK_POS : NAND_SMALL_BADBLOCK_POS;

	/* Get chip options, preserve non chip based options */
	chip->options &= ~NAND_CHIPOPTIONS_MSK;
	chip->options |= type->options & NAND_CHIPOPTIONS_MSK;

	/*
	 * Set chip as a default. Board drivers can override it, if necessary
	 */
	chip->options |= NAND_NO_AUTOINCR;

	/* Check if chip is a not a samsung device. Do not clear the
	 * options for chips which are not having an extended id.
	 */
	if (*maf_id != NAND_MFR_SAMSUNG && !type->pagesize)
		chip->options &= ~NAND_SAMSUNG_LP_OPTIONS;

	/* Check for AND chips with 4 page planes */
	if (chip->options & NAND_4PAGE_ARRAY)
		chip->erase_cmd = multi_erase_cmd;
	else
		chip->erase_cmd = single_erase_cmd;

	/* Do not replace user supplied command function ! */
	if (mtd->writesize > 512 && chip->cmdfunc == nand_command)
		chip->cmdfunc = nand_command_lp;

	printk(KERN_INFO "NAND device: Manufacturer ID:"
	       " 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id, dev_id,
	       nand_manuf_ids[maf_idx].name, type->name);

	return type;
}

/**
 * nand_scan_ident - [NAND Interface] Scan for the NAND device
 * @mtd:	     MTD device structure
 * @maxchips:	     Number of chips to scan for
 *
 * This is the first phase of the normal nand_scan() function. It
 * reads the flash ID and sets up MTD fields accordingly.
 *
 * The mtd->owner field must be set to the module of the caller.
 */
int nand_scan_ident(struct mtd_info *mtd, int maxchips)
{
	int i, busw, nand_maf_id;
	struct nand_chip *chip = mtd->priv;
	struct nand_flash_dev *type;

	/* Get buswidth to select the correct functions */
	busw = chip->options & NAND_BUSWIDTH_16;
	/* Set the default functions */
	nand_set_defaults(chip, busw);

	/* Read the flash type */
	type = nand_get_flash_type(mtd, chip, busw, &nand_maf_id);

	if (IS_ERR(type)) {
		printk(KERN_WARNING "No NAND device found!!!\n");
		chip->select_chip(mtd, -1);
		return PTR_ERR(type);
	}

	/* Check for a chip array */
	for (i = 1; i < maxchips; i++) {
		chip->select_chip(mtd, i);
		/* See comment in nand_get_flash_type for reset */
		chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
		/* Send the command for reading device ID */
		chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
		/* Read manufacturer and device IDs */
		if (nand_maf_id != chip->read_byte(mtd) ||
		    type->id != chip->read_byte(mtd))
			break;
	}
	if (i > 1)
		printk(KERN_INFO "%d NAND chips detected\n", i);

	/* Store the number of chips and calc total size for mtd */
	chip->numchips = i;
	mtd->size = i * chip->chipsize;

	return 0;
}


/**
 * nand_scan_tail - [NAND Interface] Scan for the NAND device
 * @mtd:	    MTD device structure
 *
 * This is the second phase of the normal nand_scan() function. It
 * fills out all the uninitialized function pointers with the defaults
 * and scans for a bad block table if appropriate.
 */
int nand_scan_tail(struct mtd_info *mtd)
{
	int i;
	struct nand_chip *chip = mtd->priv;
	struct nand_ecc_ctrl *ecc = &chip->ecc;

	if (!(chip->options & NAND_OWN_BUFFERS))
		chip->buffers = kmalloc(sizeof(*chip->buffers), GFP_KERNEL);
	if (!chip->buffers)
		return -ENOMEM;

	/* Set the internal oob buffer location, just after the page data */
	chip->oob_poi = chip->buffers->databuf + mtd->writesize;

	/*
	 * If no default placement scheme is given, select an appropriate one
	 */
	if (!ecc->layout && (ecc->mode != NAND_ECC_SOFT_BCH)) {
		switch (mtd->oobsize) {
		case 8:
			chip->ecc.layout = &nand_oob_8;
			break;
		case 16:
			chip->ecc.layout = &nand_oob_16;
			break;
		case 64:
			chip->ecc.layout = &nand_oob_64;
			break;
		case 128:
			chip->ecc.layout = &nand_oob_128;
			break;
                case 224:
			chip->ecc.layout = &nand_oob_224;
			break;

		default:
			printk(KERN_WARNING "No oob scheme defined for "
			       "oobsize %d\n", mtd->oobsize);
			BUG();
		}
	}

	if (!chip->write_page)
		chip->write_page = nand_write_page;

	/*
	 * check ECC mode, default to software if 3byte/512byte hardware ECC is
	 * selected and we have 256 byte pagesize fallback to software ECC
	 */

	switch (chip->ecc.mode) {
	case NAND_ECC_HW_OOB_FIRST:
		/* Similar to NAND_ECC_HW, but a separate read_page handle */
		if (!chip->ecc.calculate || !chip->ecc.correct ||
		     !chip->ecc.hwctl) {
			printk(KERN_WARNING "No ECC functions supplied; "
			       "Hardware ECC not possible\n");
			BUG();
		}
		if (!chip->ecc.read_page)
			chip->ecc.read_page = nand_read_page_hwecc_oob_first;

	case NAND_ECC_HW:
		/* Use standard hwecc read page function ? */
		if (!chip->ecc.read_page)
			chip->ecc.read_page = nand_read_page_hwecc;
		if (!chip->ecc.write_page)
			chip->ecc.write_page = nand_write_page_hwecc;
		if (!chip->ecc.read_page_raw)
			chip->ecc.read_page_raw = nand_read_page_raw;
		if (!chip->ecc.write_page_raw)
			chip->ecc.write_page_raw = nand_write_page_raw;
		if (!chip->ecc.read_oob)
			chip->ecc.read_oob = nand_read_oob_std;
		if (!chip->ecc.write_oob)
			chip->ecc.write_oob = nand_write_oob_std;

	case NAND_ECC_HW_SYNDROME:
		if ((!chip->ecc.calculate || !chip->ecc.correct ||
		     !chip->ecc.hwctl) &&
		    (!chip->ecc.read_page ||
		     chip->ecc.read_page == nand_read_page_hwecc ||
		     !chip->ecc.write_page ||
		     chip->ecc.write_page == nand_write_page_hwecc)) {
			printk(KERN_WARNING "No ECC functions supplied; "
			       "Hardware ECC not possible\n");
			BUG();
		}
		/* Use standard syndrome read/write page function ? */
		if (!chip->ecc.read_page)
			chip->ecc.read_page = nand_read_page_syndrome;
		if (!chip->ecc.write_page)
			chip->ecc.write_page = nand_write_page_syndrome;
		if (!chip->ecc.read_page_raw)
			chip->ecc.read_page_raw = nand_read_page_raw_syndrome;
		if (!chip->ecc.write_page_raw)
			chip->ecc.write_page_raw = nand_write_page_raw_syndrome;
		if (!chip->ecc.read_oob)
			chip->ecc.read_oob = nand_read_oob_syndrome;
		if (!chip->ecc.write_oob)
			chip->ecc.write_oob = nand_write_oob_syndrome;

		if (mtd->writesize >= chip->ecc.size)
			break;
		printk(KERN_WARNING "%d byte HW ECC not possible on "
		       "%d byte page size, fallback to SW ECC\n",
		       chip->ecc.size, mtd->writesize);
		chip->ecc.mode = NAND_ECC_SOFT;

	case NAND_ECC_SOFT:
		chip->ecc.calculate = nand_calculate_ecc;
		chip->ecc.correct = nand_correct_data;
		chip->ecc.read_page = nand_read_page_swecc;
		chip->ecc.read_subpage = nand_read_subpage;
		chip->ecc.write_page = nand_write_page_swecc;
		chip->ecc.read_page_raw = nand_read_page_raw;
		chip->ecc.write_page_raw = nand_write_page_raw;
		chip->ecc.read_oob = nand_read_oob_std;
		chip->ecc.write_oob = nand_write_oob_std;
		if (!chip->ecc.size)
			chip->ecc.size = 256;
		chip->ecc.bytes = 3;
		break;

	case NAND_ECC_NONE:
		printk(KERN_WARNING "NAND_ECC_NONE selected by board driver. "
		       "This is not recommended !!\n");
		chip->ecc.read_page = nand_read_page_raw;
		chip->ecc.write_page = nand_write_page_raw;
		chip->ecc.read_oob = nand_read_oob_std;
		chip->ecc.read_page_raw = nand_read_page_raw;
		chip->ecc.write_page_raw = nand_write_page_raw;
		chip->ecc.write_oob = nand_write_oob_std;
		chip->ecc.size = mtd->writesize;
		chip->ecc.bytes = 0;
		break;
	case NAND_ECC_SOFT_BCH:
		if (!mtd_nand_has_bch()) {
			pr_warn("CONFIG_MTD_NAND_ECC_BCH not enabled\n");
			BUG();
		}
		ecc->calculate = nand_bch_calculate_ecc;
		ecc->correct = nand_bch_correct_data;
		ecc->read_page = nand_read_page_swecc;
		ecc->read_subpage = nand_read_subpage;
		ecc->write_page = nand_write_page_swecc;
		ecc->read_page_raw = nand_read_page_raw;
		ecc->write_page_raw = nand_write_page_raw;
		ecc->read_oob = nand_read_oob_std;
		ecc->write_oob = nand_write_oob_std;
		/*
		 * Board driver should supply ecc.size and ecc.strength values
		 * to select how many bits are correctable. Otherwise, default
		 * to 4 bits for large page devices.
		 */
		if (!ecc->size && (mtd->oobsize >= 64)) {
			ecc->size = 512;
			ecc->strength = 4;
		}

		/* See nand_bch_init() for details. */
		ecc->bytes = DIV_ROUND_UP(
				ecc->strength * fls(8 * ecc->size), 8);
		ecc->priv = nand_bch_init(mtd, ecc->size, ecc->bytes,
					       &ecc->layout);
		if (!ecc->priv) {
			pr_warn("BCH ECC initialization failed!\n");
			BUG();
		}
		break;

	default:
		printk(KERN_WARNING "Invalid NAND_ECC_MODE %d\n",
		       chip->ecc.mode);
		BUG();
	}

	/*
	 * The number of bytes available for a client to place data into
	 * the out of band area
	 */
	chip->ecc.layout->oobavail = 0;
	for (i = 0; chip->ecc.layout->oobfree[i].length
			&& i < ARRAY_SIZE(chip->ecc.layout->oobfree); i++)
		chip->ecc.layout->oobavail +=
			chip->ecc.layout->oobfree[i].length;
	mtd->oobavail = chip->ecc.layout->oobavail;

	/*
	 * Set the number of read / write steps for one page depending on ECC
	 * mode
	 */
	chip->ecc.steps = mtd->writesize / chip->ecc.size;
	if(chip->ecc.steps * chip->ecc.size != mtd->writesize) {
		printk(KERN_WARNING "Invalid ecc parameters\n");
		BUG();
	}
	chip->ecc.total = chip->ecc.steps * chip->ecc.bytes;

	/*
	 * Allow subpage writes up to ecc.steps. Not possible for MLC
	 * FLASH.
	 */
	if (!(chip->options & NAND_NO_SUBPAGE_WRITE) &&
	    !(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {
		switch(chip->ecc.steps) {
		case 2:
			mtd->subpage_sft = 1;
			break;
		case 4:
		case 8:
		case 16:
			mtd->subpage_sft = 2;
			break;
		}
	}
	chip->subpagesize = mtd->writesize >> mtd->subpage_sft;

	/* Initialize state */
	chip->state = FL_READY;

	/* De-select the device */
	chip->select_chip(mtd, -1);

	/* Invalidate the pagebuffer reference */
	chip->pagebuf = -1;

	/* Fill in remaining MTD driver data */
	mtd->type = MTD_NANDFLASH;
	mtd->flags = MTD_CAP_NANDFLASH;
	mtd->erase = nand_erase;
	mtd->point = NULL;
	mtd->unpoint = NULL;
	mtd->read = nand_read;
	mtd->write = nand_write;
	mtd->read_oob = nand_read_oob;
	mtd->write_oob = nand_write_oob;
	mtd->sync = nand_sync;
	mtd->lock = NULL;
	mtd->unlock = NULL;
	mtd->suspend = nand_suspend;
	mtd->resume = nand_resume;
	mtd->block_isbad = nand_block_isbad;
	mtd->block_markbad = nand_block_markbad;

	/* propagate ecc.layout to mtd_info */
	mtd->ecclayout = chip->ecc.layout;

	/* Check, if we should skip the bad block table scan */
	if (chip->options & NAND_SKIP_BBTSCAN)
		return 0;

	/* Build bad block table */
	return chip->scan_bbt(mtd);
}

/* is_module_text_address() isn't exported, and it's mostly a pointless
   test if this is a module _anyway_ -- they'd have to try _really_ hard
   to call us from in-kernel code if the core NAND support is modular. */
#ifdef MODULE
#define caller_is_module() (1)
#else
#define caller_is_module() \
	is_module_text_address((unsigned long)__builtin_return_address(0))
#endif

/**
 * nand_scan - [NAND Interface] Scan for the NAND device
 * @mtd:	MTD device structure
 * @maxchips:	Number of chips to scan for
 *
 * This fills out all the uninitialized function pointers
 * with the defaults.
 * The flash ID is read and the mtd/chip structures are
 * filled with the appropriate values.
 * The mtd->owner field must be set to the module of the caller
 *
 */
int nand_scan(struct mtd_info *mtd, int maxchips)
{
	int ret;

	/* Many callers got this wrong, so check for it for a while... */
	if (!mtd->owner && caller_is_module()) {
		printk(KERN_CRIT "%s called with NULL mtd->owner!\n",
				__func__);
		BUG();
	}

	ret = nand_scan_ident(mtd, maxchips);
	if (!ret)
		ret = nand_scan_tail(mtd);
	return ret;
}

/**
 * nand_release - [NAND Interface] Free resources held by the NAND device
 * @mtd:	MTD device structure
*/
void nand_release(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;

	if (chip->ecc.mode == NAND_ECC_SOFT_BCH)
		nand_bch_free((struct nand_bch_control *)chip->ecc.priv);

#ifdef CONFIG_MTD_PARTITIONS
	/* Deregister partitions */
	del_mtd_partitions(mtd);
#endif
	/* Deregister the device */
	del_mtd_device(mtd);

	/* Free bad block table memory */
	kfree(chip->bbt);
	if (!(chip->options & NAND_OWN_BUFFERS))
		kfree(chip->buffers);
}

EXPORT_SYMBOL_GPL(nand_scan);
EXPORT_SYMBOL_GPL(nand_scan_ident);
EXPORT_SYMBOL_GPL(nand_scan_tail);
EXPORT_SYMBOL_GPL(nand_release);

static int __init nand_base_init(void)
{
	led_trigger_register_simple("nand-disk", &nand_led_trigger);
	return 0;
}

static void __exit nand_base_exit(void)
{
	led_trigger_unregister_simple(nand_led_trigger);
}

module_init(nand_base_init);
module_exit(nand_base_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steven J. Hill , Thomas Gleixner ");
MODULE_DESCRIPTION("Generic NAND flash driver code");

==========================================================================

分割线,上面是核心层的代码,内核标配,以下是与自己flash驱动编写相关的代码

==========================================================================

先填充一个nand_chip的结构,必备的

    u8 id;
	struct nand_chip *this = &info->nand_chip;

	this->options = NAND_CACHEPRG;//芯片特性
	this->waitfunc = my_nand_waitfunc;//等待芯片完成回调
	this->select_chip = my_nand_select_chip;//有些nand有几块chip,如果只有一片,直接返回0
	this->dev_ready = my_nand_dev_ready;//等待设备准备好
	this->read_word = my_nand_read_word;//读一个字
	this->read_byte = my_nand_read_byte;//读一个byte,在读id时要用到
	this->read_buf = my_nand_read_buf;//读取buf,实现自己需要读取的大小
	this->write_buf = my_nand_write_buf;//写buf,实现需要写数据的大小
	this->verify_buf = my_nand_verify_buf;//如果是verify写,就会将写入的数读出来跟写的比较

	this->ecc.mode = NAND_ECC_NONE;//ecc模式,不同的模式读写oob不一样
	this->ecc.hwctl = my_nand_ecc_hwctl;//如果是硬件ecc,这里选择的是ecc none,直接返回0
	this->ecc.calculate = my_nand_ecc_calculate;//同上
	this->ecc.correct = my_nand_ecc_correct;//同上
        this->ecc.size = 2048;//2k也大小的ecc大小
	this->ecc.bytes = 24;//ecc的位数
	
	id = nand_read_id(0x0);	//
	this->cmdfunc = my_nand_cmdfunc;//操作命令函数
	this->ecc.layout = &my_hw_largepage_ecclayout;//与ecc相关的表,具体与平台相关

	mtd->owner = THIS_MODULE;

剩下的重要的函数就是 my_nand_cmdfunc的实现

这个命令函数实现了对芯片的读、写、擦除和读oob,写oob,读id

static void my_nand_cmdfunc(struct mtd_info *mtd, unsigned command,
			      int column, int page_addr)
{
	struct my_nand_info *info = mtd->priv;
	unsigned cmd_prev;
	u8 fail_bit,ready_bit,wp_bit,feature;
	
	cmd_prev = info->cmd;
	init_completion(&info->cmd_complete);

	info->cmd = command;
	info->page_addr = page_addr;
	switch (command) {
	case NAND_CMD_READOOB://读oob命令
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}

		info->state = STATE_BUSY;
		info->buf_count = mtd->oobsize;
		info->buf_start = 0;
		info->cac_size = info->buf_count;
		if (info->buf_count <= 0)
			break;
		nand_page_read_oob(info->data_buff ,page_addr,mtd->oobsize);//根据芯片手册实现
		break;
	case NAND_CMD_READ0://读数据命令
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		info->buf_count = mtd->oobsize + mtd->writesize;
		info->buf_start = 0;
		info->cac_size = info->buf_count;
		if (info->buf_count <= 0)
			break;
		nand_page_read(info->data_buff,page_addr,info->buf_count);////根据芯片手册实现
		break;
	case NAND_CMD_SEQIN://在写前会调用这个命令,用于找到页地址和读取写入大小
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		info->buf_count = mtd->oobsize + mtd->writesize - column;
		info->buf_start = 0;
		info->seqin_column = column;
		info->seqin_page_addr = page_addr;
		complete(&info->cmd_complete);
		break;
	case NAND_CMD_PAGEPROG://写命令
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		if (cmd_prev != NAND_CMD_SEQIN) {
			printk("Prev cmd don't complete...\n");
			break;
		}
		if (info->buf_count <= 0)
			break;
		nand_page_program(info->data_buff,info->seqin_page_addr,info->seqin_column,info->buf_start);//根据芯片实现
		break;
	case NAND_CMD_RESET://复位芯片
		/*nand cmd set */
		nand_reset();//根据芯片实现
		complete(&info->cmd_complete);
		break;
	case NAND_CMD_ERASE1://擦除命令
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		nand_erase_one_block(page_addr);//根据芯片实现
		info->state = STATE_READY;
		complete(&info->cmd_complete);
		break;
	case NAND_CMD_STATUS://获取芯片状态,读写操作时会查询该状态
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		info->buf_count = 0x1;
		info->buf_start = 0x0;	
		feature = nand_get_feature(NAND_STATUS_REG);//根据芯片实现
		wp_bit = NAND_STATUS_WP;
		ready_bit = ((~feature)&NAND_STATUS_OIP)<<6;
		if(cmd_prev == NAND_CMD_ERASE1){
			fail_bit = (feature&NAND_STATUS_EFAIL)>>2;
		}else if(cmd_prev == NAND_CMD_PAGEPROG){
			fail_bit = (feature&NAND_STATUS_PFAIL)>>3;
		}
		*(unsigned char *)info->data_buff = wp_bit|ready_bit|fail_bit;
		break;
	case NAND_CMD_READID://读id命令,芯片扫描时调用该命令
		if (info->state == STATE_BUSY) {
			printk("nandflash chip if busy...\n");
			return;
		}
		info->state = STATE_BUSY;
		info->buf_count = 0x4;
		info->buf_start = 0;

		{	u8 id0,id1;

			unsigned char *data =
			    (unsigned char *)(info->data_buff);
			
			id0 = nand_read_id(0x0);//厂家ID
			id1 = nand_read_id(0x1);//设备ID
			
#ifdef NAND_DEBUG
			printk("id_val_l=0x%08x\nid_val_h=0x%08x\n", id0,
			       id1);
#endif
			data[0] = id0;
			data[1] = id1;
			data[2] = 0x0;//
			data[3] = 0x15;//extid
#ifdef NAND_DEBUG
			printk(KERN_ERR
			       "IDS=============================0x%x\n",
			       *((int *)(info->data_buff)));
#endif
			  
		}
		complete(&info->cmd_complete);
		break;
	case NAND_CMD_ERASE2:
	case NAND_CMD_READ1:
		complete(&info->cmd_complete);
		break;
	default:
		printk(KERN_ERR "non-supported command.\n");
		complete(&info->cmd_complete);
		break;
	}
	wait_for_completion_timeout(&info->cmd_complete, timeout);
	info->state = STATE_READY;
}




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