/*
 *  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 (sjhill@realitydiluted.com)
 *		  2002-2006 Thomas Gleixner (tglx@linutronix.de)
 *
 *  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 <common.h>

#define ENOTSUPP	524	/* Operation is not supported */

#include <malloc.h>
#include <watchdog.h>
#include <linux/err.h>
#include <linux/mtd/compat.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>

#ifdef CONFIG_MTD_PARTITIONS
#include <linux/mtd/partitions.h>
#endif

#include <asm/io.h>
#include <asm/errno.h>

/*
 * CONFIG_SYS_NAND_RESET_CNT is used as a timeout mechanism when resetting
 * a flash.  NAND flash is initialized prior to interrupts so standard timers
 * can't be used.  CONFIG_SYS_NAND_RESET_CNT should be set to a value
 * which is greater than (max NAND reset time / NAND status read time).
 * A conservative default of 200000 (500 us / 25 ns) is used as a default.
 */
#ifndef CONFIG_SYS_NAND_RESET_CNT
#define CONFIG_SYS_NAND_RESET_CNT 200000
#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 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);

static int nand_wait(struct mtd_info *mtd, struct nand_chip *this);

/**
 * 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 *this = mtd->priv;
	this->select_chip(mtd, -1);	/* De-select the NAND device */
}

/**
 * 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
 */
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
 */
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->options & NAND_BBT_SCANNED)) {
		chip->options |= NAND_BBT_SCANNED;
		chip->scan_bbt(mtd);
	}

	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;
	u32 timeo = (CONFIG_SYS_HZ * 20) / 1000;
	u32 time_start;

	time_start = get_timer(0);

	/* wait until command is processed or timeout occures */
	while (get_timer(time_start) < timeo) {
		if (chip->dev_ready)
			if (chip->dev_ready(mtd))
				break;
	}
}

/**
 * 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;
	uint32_t rst_sts_cnt = CONFIG_SYS_NAND_RESET_CNT;

	/*
	 * 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) &&
			(rst_sts_cnt--));
		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;
	uint32_t rst_sts_cnt = CONFIG_SYS_NAND_RESET_CNT;

	/* 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) &&
			(rst_sts_cnt--));
		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 *this, struct mtd_info *mtd, int new_state)
{
	this->state = new_state;
	return 0;
}

/**
 * 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 *this)
{
	unsigned long	timeo;
	int state = this->state;
	u32 time_start;

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

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

	time_start = get_timer(0);

	while (1) {
		if (get_timer(time_start) > timeo) {
			printf("Timeout!");
			return 0x01;
		}

		if (this->dev_ready) {
			if (this->dev_ready(mtd))
				break;
		} else {
			if (this->read_byte(mtd) & NAND_STATUS_READY)
				break;
		}
	}
#ifdef PPCHAMELON_NAND_TIMER_HACK
	time_start = get_timer(0);
	while (get_timer(time_start) < 10)
		;
#endif /*  PPCHAMELON_NAND_TIMER_HACK */

	return this->read_byte(mtd);
}

/**
 * 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) {
		WATCHDOG_RESET();

		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;

	MTDDEBUG (MTD_DEBUG_LEVEL3, "nand_read_oob: from = 0x%08Lx, len = %i\n",
		  (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)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt to start read outside oob\n");
		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)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt read beyond end of device\n");
		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) {
		WATCHDOG_RESET();
		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) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt read beyond end of device\n");
		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;

	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)) {
		printk (KERN_NOTICE "nand_do_write_ops: Device is write protected\n");
		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) {
		WATCHDOG_RESET();

		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 writes 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;

	MTDDEBUG (MTD_DEBUG_LEVEL3, "nand_write_oob: to = 0x%08x, len = %i\n",
		  (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) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_write_oob: "
			  "Attempt to write past end of page\n");
		return -EINVAL;
	}

	if (unlikely(ops->ooboffs >= len)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt to start write outside oob\n");
		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)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt write beyond end of device\n");
		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) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: "
			  "Attempt read beyond end of device\n");
		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[CONFIG_SYS_NAND_MAX_CHIPS] = {0};
	unsigned int bbt_masked_page = 0xffffffff;
	loff_t len;

	MTDDEBUG(MTD_DEBUG_LEVEL3, "nand_erase: start = 0x%012llx, "
		 "len = %llu\n", (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)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_erase: Unaligned address\n");
		return -EINVAL;
	}

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

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

	instr->fail_addr = 0xffffffff;

	/* 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)) {
		MTDDEBUG (MTD_DEBUG_LEVEL0,
			  "nand_erase: Device is write protected!!!\n");
		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) {
		WATCHDOG_RESET();
		/*
		 * 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 "nand_erase: attempt to erase a "
			       "bad block at page 0x%08x\n", 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) {
			MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_erase: "
				  "Failed erase, page 0x%08x\n", 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 */
		MTDDEBUG (MTD_DEBUG_LEVEL0, "nand_erase_nand: nand_update_bbt "
			  "(%d:0x%0llx 0x%0x)\n", 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;

	MTDDEBUG (MTD_DEBUG_LEVEL3, "nand_sync: called\n");

	/* 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);
}

/*
 * 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;
}

#ifdef CONFIG_SYS_NAND_ONFI_DETECTION
static u16 onfi_crc16(u16 crc, u8 const *p, size_t len)
{
	int i;

	while (len--) {
		crc ^= *p++ << 8;
		for (i = 0; i < 8; i++)
			crc = (crc << 1) ^ ((crc & 0x8000) ? 0x8005 : 0);
	}

	return crc;
}

/*
 * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise
 */
static int nand_flash_detect_onfi(struct mtd_info *mtd,
					struct nand_chip *chip,
					int *busw)
{
	struct nand_onfi_params *p = &chip->onfi_params;
	int i;
	int val;

	chip->cmdfunc(mtd, NAND_CMD_READID, 0x20, -1);
	if (chip->read_byte(mtd) != 'O' || chip->read_byte(mtd) != 'N' ||
		chip->read_byte(mtd) != 'F' || chip->read_byte(mtd) != 'I')
		return 0;

	printk(KERN_INFO "ONFI flash detected\n");
	chip->cmdfunc(mtd, NAND_CMD_PARAM, 0, -1);
	for (i = 0; i < 3; i++) {
		chip->read_buf(mtd, (uint8_t *)p, sizeof(*p));
		if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) ==
						le16_to_cpu(p->crc)) {
			printk(KERN_INFO "ONFI param page %d valid\n", i);
			break;
		}
	}

	if (i == 3)
		return 0;

	/* check version */
	val = le16_to_cpu(p->revision);
	if (val & (1 << 5))
		chip->onfi_version = 23;
	else if (val & (1 << 4))
		chip->onfi_version = 22;
	else if (val & (1 << 3))
		chip->onfi_version = 21;
	else if (val & (1 << 2))
		chip->onfi_version = 20;
	else if (val & (1 << 1))
		chip->onfi_version = 10;
	else
		chip->onfi_version = 0;

	if (!chip->onfi_version) {
		printk(KERN_INFO "%s: unsupported ONFI "
					"version: %d\n", __func__, val);
		return 0;
	}

	if (!mtd->name)
		mtd->name = p->model;

	mtd->writesize = le32_to_cpu(p->byte_per_page);
	mtd->erasesize = le32_to_cpu(p->pages_per_block) * mtd->writesize;
	mtd->oobsize = le16_to_cpu(p->spare_bytes_per_page);
	chip->chipsize = (uint64_t)le32_to_cpu(p->blocks_per_lun) * mtd->erasesize;
	*busw = 0;
	if (le16_to_cpu(p->features) & 1)
		*busw = NAND_BUSWIDTH_16;

	return 1;
}
#else
static inline int nand_flash_detect_onfi(struct mtd_info *mtd,
					struct nand_chip *chip,
					int *busw)
{
	return 0;
}
#endif

static void nand_flash_detect_non_onfi(struct mtd_info *mtd,
					struct nand_chip *chip,
					const struct nand_flash_dev *type,
					int *busw)
{
	/* 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;
	}
}

/*
 * Get the flash and manufacturer id and lookup if the type is supported
 */
static const struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
						  struct nand_chip *chip,
						  int busw,
						  int *maf_id, int *dev_id,
						  const struct nand_flash_dev *type)
{
	int ret, 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);
	}

	if (!type)
		type = nand_flash_ids;

	for (; type->name != NULL; type++)
		if (*dev_id == type->id)
			break;

	if (!type->name) {
		/* supress warning if there is no nand */
		if (*maf_id != 0x00 && *maf_id != 0xff &&
		    *dev_id  != 0x00 && *dev_id  != 0xff)
			printk(KERN_INFO "%s: unknown NAND device: "
				"Manufacturer ID: 0x%02x, Chip ID: 0x%02x\n",
				__func__, *maf_id, *dev_id);
		return ERR_PTR(-ENODEV);
	}

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

	chip->chipsize = (uint64_t)type->chipsize << 20;
	chip->onfi_version = 0;

	ret = nand_flash_detect_onfi(mtd, chip, &busw);
	if (!ret)
		nand_flash_detect_non_onfi(mtd, chip, type, &busw);

	/* 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;

	/* 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)) + 31;

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

	/* 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;

	MTDDEBUG (MTD_DEBUG_LEVEL0, "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
 * @table:	     Alternative NAND ID table
 *
 * 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,
		    const struct nand_flash_dev *table)
{
	int i, busw, nand_maf_id, nand_dev_id;
	struct nand_chip *chip = mtd->priv;
	const 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, &nand_dev_id, table);

	if (IS_ERR(type)) {
#ifndef CONFIG_SYS_NAND_QUIET_TEST
		printk(KERN_WARNING "No NAND device found!!!\n");
#endif
		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) ||
		    nand_dev_id != chip->read_byte(mtd))
			break;
	}
#ifdef DEBUG
	if (i > 1)
		printk(KERN_INFO "%d NAND chips detected\n", i);
#endif

	/* 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;

	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 (!chip->ecc.layout) {
		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;
		default:
			printk(KERN_WARNING "No oob scheme defined for "
			       "oobsize %d\n", mtd->oobsize);
		}
	}

	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;
		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;

	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->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)
		chip->options |= NAND_BBT_SCANNED;

	return 0;
}

/**
 * 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;

	ret = nand_scan_ident(mtd, maxchips, NULL);
	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;

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

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