drivers/mtd/nand/nand_base.c

/*
 *  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/tech/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.
 *
 * 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 <linux/module.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/compatmac.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/leds.h>
#include <asm/io.h>

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

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

static struct nand_oobinfo nand_oob_16 = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.eccbytes = 6,
	.eccpos = {0, 1, 2, 3, 6, 7},
	.oobfree = {{8, 8}}
};

static struct nand_oobinfo nand_oob_64 = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.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 = {{2, 38}}
};

/* This is used for padding purposes in nand_write_oob */
static uint8_t ffchars[] = {
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};

/*
 * NAND low-level MTD interface functions
 */
static void nand_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len);
static void nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len);
static int nand_verify_buf(struct mtd_info *mtd, const uint8_t *buf, int len);

static int nand_read(struct mtd_info *mtd, loff_t from, size_t len,
		     size_t *retlen, uint8_t *buf);
static int nand_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
			 size_t *retlen, uint8_t *buf);
static int nand_write(struct mtd_info *mtd, loff_t to, size_t len,
		      size_t *retlen, const uint8_t *buf);
static int nand_write_oob(struct mtd_info *mtd, loff_t to, size_t len,
			  size_t *retlen, const uint8_t *buf);
static int nand_erase(struct mtd_info *mtd, struct erase_info *instr);
static void nand_sync(struct mtd_info *mtd);

/* Some internal functions */
static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
			   int page, uint8_t * oob_buf,
			   struct nand_oobinfo *oobsel, int mode);
#ifdef CONFIG_MTD_NAND_VERIFY_WRITE
static int nand_verify_pages(struct mtd_info *mtd, struct nand_chip *chip,
			     int page, int numpages, uint8_t *oob_buf,
			     struct nand_oobinfo *oobsel, int chipnr,
			     int oobmode);
#else
#define nand_verify_pages(...) (0)
#endif

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

/*
 * For devices which display every fart in the system on a seperate 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
 * @chip:	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:
		chip->cmd_ctrl(mtd, NAND_CMD_NONE,
			       NAND_NCE | NAND_CTRL_CHANGE);
		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;

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

		nand_get_device(chip, mtd, FL_READING);

		/* Select the NAND device */
		chip->select_chip(mtd, chipnr);
	} else
		page = (int)ofs;

	if (chip->options & NAND_BUSWIDTH_16) {
		chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos & 0xFE,
			      page & chip->pagemask);
		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 & chip->pagemask);
		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 };
	size_t retlen;
	int block;

	/* 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)
		return nand_update_bbt(mtd, ofs);

	/* We write two bytes, so we dont have to mess with 16 bit access */
	ofs += mtd->oobsize + (chip->badblockpos & ~0x01);
	return nand_write_oob(mtd, ofs, 2, &retlen, buf);
}

/**
 * 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.
 */
static 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);
}

/**
 * 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:
		chip->cmd_ctrl(mtd, NAND_CMD_NONE, NAND_NCE);
		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);
		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_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);
		chip->cmd_ctrl(mtd, NAND_CMD_NONE, NAND_NCE);
		while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) ;
		return;

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

		/* 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
 * @this:	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 independend devices */
	/* Hardware controller shared among independend 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
 * @this:	NAND chip structure
 * @state:	state to select the max. timeout value
 *
 * 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, int state)
{

	unsigned long timeo = jiffies;
	int status;

	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)) {
		/* Check, if we were interrupted */
		if (chip->state != state)
			return 0;

		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_write_page - [GENERIC] write one page
 * @mtd:	MTD device structure
 * @this:	NAND chip structure
 * @page: 	startpage inside the chip, must be called with (page & chip->pagemask)
 * @oob_buf:	out of band data buffer
 * @oobsel:	out of band selecttion structre
 * @cached:	1 = enable cached programming if supported by chip
 *
 * Nand_page_program function is used for write and writev !
 * This function will always program a full page of data
 * If you call it with a non page aligned buffer, you're lost :)
 *
 * Cached programming is not supported yet.
 */
static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip, int page,
			   uint8_t *oob_buf, struct nand_oobinfo *oobsel, int cached)
{
	int i, status;
	uint8_t ecc_code[32];
	int eccmode = oobsel->useecc ? chip->ecc.mode : NAND_ECC_NONE;
	int *oob_config = oobsel->eccpos;
	int datidx = 0, eccidx = 0, eccsteps = chip->ecc.steps;
	int eccbytes = 0;

	/* FIXME: Enable cached programming */
	cached = 0;

	/* Send command to begin auto page programming */
	chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);

	/* Write out complete page of data, take care of eccmode */
	switch (eccmode) {
		/* No ecc, write all */
	case NAND_ECC_NONE:
		printk(KERN_WARNING "Writing data without ECC to NAND-FLASH is not recommended\n");
		chip->write_buf(mtd, chip->data_poi, mtd->writesize);
		break;

		/* Software ecc 3/256, write all */
	case NAND_ECC_SOFT:
		for (; eccsteps; eccsteps--) {
			chip->ecc.calculate(mtd, &chip->data_poi[datidx], ecc_code);
			for (i = 0; i < 3; i++, eccidx++)
				oob_buf[oob_config[eccidx]] = ecc_code[i];
			datidx += chip->ecc.size;
		}
		chip->write_buf(mtd, chip->data_poi, mtd->writesize);
		break;
	default:
		eccbytes = chip->ecc.bytes;
		for (; eccsteps; eccsteps--) {
			/* enable hardware ecc logic for write */
			chip->ecc.hwctl(mtd, NAND_ECC_WRITE);
			chip->write_buf(mtd, &chip->data_poi[datidx], chip->ecc.size);
			chip->ecc.calculate(mtd, &chip->data_poi[datidx], ecc_code);
			for (i = 0; i < eccbytes; i++, eccidx++)
				oob_buf[oob_config[eccidx]] = ecc_code[i];
			/* If the hardware ecc provides syndromes then
			 * the ecc code must be written immidiately after
			 * the data bytes (words) */
			if (chip->options & NAND_HWECC_SYNDROME)
				chip->write_buf(mtd, ecc_code, eccbytes);
			datidx += chip->ecc.size;
		}
		break;
	}

	/* Write out OOB data */
	if (chip->options & NAND_HWECC_SYNDROME)
		chip->write_buf(mtd, &oob_buf[oobsel->eccbytes], mtd->oobsize - oobsel->eccbytes);
	else
		chip->write_buf(mtd, oob_buf, mtd->oobsize);

	/* Send command to actually program the data */
	chip->cmdfunc(mtd, cached ? NAND_CMD_CACHEDPROG : NAND_CMD_PAGEPROG, -1, -1);

	if (!cached) {
		/* call wait ready function */
		status = chip->waitfunc(mtd, chip, FL_WRITING);

		/* 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);
		}

		/* See if device thinks it succeeded */
		if (status & NAND_STATUS_FAIL) {
			DEBUG(MTD_DEBUG_LEVEL0, "%s: " "Failed write, page 0x%08x, ", __FUNCTION__, page);
			return -EIO;
		}
	} else {
		/* FIXME: Implement cached programming ! */
		/* wait until cache is ready */
		// status = chip->waitfunc (mtd, this, FL_CACHEDRPG);
	}
	return 0;
}

#ifdef CONFIG_MTD_NAND_VERIFY_WRITE
/**
 * nand_verify_pages - [GENERIC] verify the chip contents after a write
 * @mtd:	MTD device structure
 * @this:	NAND chip structure
 * @page:	startpage inside the chip, must be called with (page & chip->pagemask)
 * @numpages:	number of pages to verify
 * @oob_buf:	out of band data buffer
 * @oobsel:	out of band selecttion structre
 * @chipnr:	number of the current chip
 * @oobmode:	1 = full buffer verify, 0 = ecc only
 *
 * The NAND device assumes that it is always writing to a cleanly erased page.
 * Hence, it performs its internal write verification only on bits that
 * transitioned from 1 to 0. The device does NOT verify the whole page on a
 * byte by byte basis. It is possible that the page was not completely erased
 * or the page is becoming unusable due to wear. The read with ECC would catch
 * the error later when the ECC page check fails, but we would rather catch
 * it early in the page write stage. Better to write no data than invalid data.
 */
static int nand_verify_pages(struct mtd_info *mtd, struct nand_chip *chip, int page, int numpages,
			     uint8_t *oob_buf, struct nand_oobinfo *oobsel, int chipnr, int oobmode)
{
	int i, j, datidx = 0, oobofs = 0, res = -EIO;
	int eccsteps = chip->eccsteps;
	int hweccbytes;
	uint8_t oobdata[64];

	hweccbytes = (chip->options & NAND_HWECC_SYNDROME) ? (oobsel->eccbytes / eccsteps) : 0;

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

	for (;;) {
		for (j = 0; j < eccsteps; j++) {
			/* Loop through and verify the data */
			if (chip->verify_buf(mtd, &chip->data_poi[datidx], mtd->eccsize)) {
				DEBUG(MTD_DEBUG_LEVEL0, "%s: " "Failed write verify, page 0x%08x ", __FUNCTION__, page);
				goto out;
			}
			datidx += mtd->eccsize;
			/* Have we a hw generator layout ? */
			if (!hweccbytes)
				continue;
			if (chip->verify_buf(mtd, &chip->oob_buf[oobofs], hweccbytes)) {
				DEBUG(MTD_DEBUG_LEVEL0, "%s: " "Failed write verify, page 0x%08x ", __FUNCTION__, page);
				goto out;
			}
			oobofs += hweccbytes;
		}

		/* check, if we must compare all data or if we just have to
		 * compare the ecc bytes
		 */
		if (oobmode) {
			if (chip->verify_buf(mtd, &oob_buf[oobofs], mtd->oobsize - hweccbytes * eccsteps)) {
				DEBUG(MTD_DEBUG_LEVEL0, "%s: " "Failed write verify, page 0x%08x ", __FUNCTION__, page);
				goto out;
			}
		} else {
			/* Read always, else autoincrement fails */
			chip->read_buf(mtd, oobdata, mtd->oobsize - hweccbytes * eccsteps);

			if (oobsel->useecc != MTD_NANDECC_OFF && !hweccbytes) {
				int ecccnt = oobsel->eccbytes;

				for (i = 0; i < ecccnt; i++) {
					int idx = oobsel->eccpos[i];
					if (oobdata[idx] != oob_buf[oobofs + idx]) {
						DEBUG(MTD_DEBUG_LEVEL0, "%s: Failed ECC write verify, page 0x%08x, %6i bytes were succesful\n",
						      __FUNCTION__, page, i);
						goto out;
					}
				}
			}
		}
		oobofs += mtd->oobsize - hweccbytes * eccsteps;
		page++;
		numpages--;

		/* 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.
		 * Do this also before returning, so the chip is
		 * ready for the next command.
		 */
		if (!chip->dev_ready)
			udelay(chip->chip_delay);
		else
			nand_wait_ready(mtd);

		/* All done, return happy */
		if (!numpages)
			return 0;

		/* Check, if the chip supports auto page increment */
		if (!NAND_CANAUTOINCR(this))
			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
	}
	/*
	 * Terminate the read command. We come here in case of an error
	 * So we must issue a reset command.
	 */
 out:
	chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
	return res;
}
#endif

/**
 * 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
 *
 * This function simply calls nand_do_read_ecc with oob buffer and oobsel = NULL
 * and flags = 0xff
 */
static int nand_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, uint8_t *buf)
{
	return nand_do_read_ecc(mtd, from, len, retlen, buf, NULL, &mtd->oobinfo, 0xff);
}

/**
 * nand_do_read_ecc - [MTD Interface] Read data with 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
 * @oob_buf:	filesystem supplied oob data buffer (can be NULL)
 * @oobsel:	oob selection structure
 * @flags:	flag to indicate if nand_get_device/nand_release_device should be preformed
 *		and how many corrected error bits are acceptable:
 *		  bits 0..7 - number of tolerable errors
 *		  bit  8    - 0 == do not get/release chip, 1 == get/release chip
 *
 * NAND read with ECC
 */
int nand_do_read_ecc(struct mtd_info *mtd, loff_t from, size_t len,
		     size_t *retlen, uint8_t *buf, uint8_t *oob_buf, struct nand_oobinfo *oobsel, int flags)
{

	int i, j, col, realpage, page, end, ecc, chipnr, sndcmd = 1;
	int read = 0, oob = 0, ecc_status = 0, ecc_failed = 0;
	struct nand_chip *chip = mtd->priv;
	uint8_t *data_poi, *oob_data = oob_buf;
	uint8_t ecc_calc[32];
	uint8_t ecc_code[32];
	int eccmode, eccsteps;
	int *oob_config, datidx;
	int blockcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;
	int eccbytes;
	int compareecc = 1;
	int oobreadlen;

	DEBUG(MTD_DEBUG_LEVEL3, "nand_read_ecc: from = 0x%08x, len = %i\n", (unsigned int)from, (int)len);

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_read_ecc: Attempt read beyond end of device\n");
		*retlen = 0;
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	if (flags & NAND_GET_DEVICE)
		nand_get_device(chip, mtd, FL_READING);

	/* Autoplace of oob data ? Use the default placement scheme */
	if (oobsel->useecc == MTD_NANDECC_AUTOPLACE)
		oobsel = chip->autooob;

	eccmode = oobsel->useecc ? chip->ecc.mode : NAND_ECC_NONE;
	oob_config = oobsel->eccpos;

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

	/* First we calculate the starting page */
	realpage = (int)(from >> chip->page_shift);
	page = realpage & chip->pagemask;

	/* Get raw starting column */
	col = from & (mtd->writesize - 1);

	end = mtd->writesize;
	ecc = chip->ecc.size;
	eccbytes = chip->ecc.bytes;

	if ((eccmode == NAND_ECC_NONE) || (chip->options & NAND_HWECC_SYNDROME))
		compareecc = 0;

	oobreadlen = mtd->oobsize;
	if (chip->options & NAND_HWECC_SYNDROME)
		oobreadlen -= oobsel->eccbytes;

	/* Loop until all data read */
	while (read < len) {

		int aligned = (!col && (len - read) >= end);
		/*
		 * If the read is not page aligned, we have to read into data buffer
		 * due to ecc, else we read into return buffer direct
		 */
		if (aligned)
			data_poi = &buf[read];
		else
			data_poi = chip->data_buf;

		/* Check, if we have this page in the buffer
		 *
		 * FIXME: Make it work when we must provide oob data too,
		 * check the usage of data_buf oob field
		 */
		if (realpage == chip->pagebuf && !oob_buf) {
			/* aligned read ? */
			if (aligned)
				memcpy(data_poi, chip->data_buf, end);
			goto readdata;
		}

		/* Check, if we must send the read command */
		if (sndcmd) {
			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
			sndcmd = 0;
		}

		/* get oob area, if we have no oob buffer from fs-driver */
		if (!oob_buf || oobsel->useecc == MTD_NANDECC_AUTOPLACE ||
			oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
			oob_data = &chip->data_buf[end];

		eccsteps = chip->ecc.steps;

		switch (eccmode) {
		case NAND_ECC_NONE:{
				/* No ECC, Read in a page */
				static unsigned long lastwhinge = 0;
				if ((lastwhinge / HZ) != (jiffies / HZ)) {
					printk(KERN_WARNING
					       "Reading data from NAND FLASH without ECC is not recommended\n");
					lastwhinge = jiffies;
				}
				chip->read_buf(mtd, data_poi, end);
				break;
			}

		case NAND_ECC_SOFT:	/* Software ECC 3/256: Read in a page + oob data */
			chip->read_buf(mtd, data_poi, end);
			for (i = 0, datidx = 0; eccsteps; eccsteps--, i += 3, datidx += ecc)
				chip->ecc.calculate(mtd, &data_poi[datidx], &ecc_calc[i]);
			break;

		default:
			for (i = 0, datidx = 0; eccsteps; eccsteps--, i += eccbytes, datidx += ecc) {
				chip->ecc.hwctl(mtd, NAND_ECC_READ);
				chip->read_buf(mtd, &data_poi[datidx], ecc);

				/* HW ecc with syndrome calculation must read the
				 * syndrome from flash immidiately after the data */
				if (!compareecc) {
					/* Some hw ecc generators need to know when the
					 * syndrome is read from flash */
					chip->ecc.hwctl(mtd, NAND_ECC_READSYN);
					chip->read_buf(mtd, &oob_data[i], eccbytes);
					/* We calc error correction directly, it checks the hw
					 * generator for an error, reads back the syndrome and
					 * does the error correction on the fly */
					ecc_status = chip->ecc.correct(mtd, &data_poi[datidx], &oob_data[i], &ecc_code[i]);
					if ((ecc_status == -1) || (ecc_status > (flags && 0xff))) {
						DEBUG(MTD_DEBUG_LEVEL0, "nand_read_ecc: "
						      "Failed ECC read, page 0x%08x on chip %d\n", page, chipnr);
						ecc_failed++;
					}
				} else {
					chip->ecc.calculate(mtd, &data_poi[datidx], &ecc_calc[i]);
				}
			}
			break;
		}

		/* read oobdata */
		chip->read_buf(mtd, &oob_data[mtd->oobsize - oobreadlen], oobreadlen);

		/* Skip ECC check, if not requested (ECC_NONE or HW_ECC with syndromes) */
		if (!compareecc)
			goto readoob;

		/* Pick the ECC bytes out of the oob data */
		for (j = 0; j < oobsel->eccbytes; j++)
			ecc_code[j] = oob_data[oob_config[j]];

		/* correct data, if necessary */
		for (i = 0, j = 0, datidx = 0; i < chip->ecc.steps; i++, datidx += ecc) {
			ecc_status = chip->ecc.correct(mtd, &data_poi[datidx], &ecc_code[j], &ecc_calc[j]);

			/* Get next chunk of ecc bytes */
			j += eccbytes;

			/* Check, if we have a fs supplied oob-buffer,
			 * This is the legacy mode. Used by YAFFS1
			 * Should go away some day
			 */
			if (oob_buf && oobsel->useecc == MTD_NANDECC_PLACE) {
				int *p = (int *)(&oob_data[mtd->oobsize]);
				p[i] = ecc_status;
			}

			if ((ecc_status == -1) || (ecc_status > (flags && 0xff))) {
				DEBUG(MTD_DEBUG_LEVEL0, "nand_read_ecc: " "Failed ECC read, page 0x%08x\n", page);
				ecc_failed++;
			}
		}

	      readoob:
		/* check, if we have a fs supplied oob-buffer */
		if (oob_buf) {
			/* without autoplace. Legacy mode used by YAFFS1 */
			switch (oobsel->useecc) {
			case MTD_NANDECC_AUTOPLACE:
			case MTD_NANDECC_AUTOPL_USR:
				/* Walk through the autoplace chunks */
				for (i = 0; oobsel->oobfree[i][1]; i++) {
					int from = oobsel->oobfree[i][0];
					int num = oobsel->oobfree[i][1];
					memcpy(&oob_buf[oob], &oob_data[from], num);
					oob += num;
				}
				break;
			case MTD_NANDECC_PLACE:
				/* YAFFS1 legacy mode */
				oob_data += chip->ecc.steps * sizeof(int);
			default:
				oob_data += mtd->oobsize;
			}
		}
	readdata:
		/* Partial page read, transfer data into fs buffer */
		if (!aligned) {
			for (j = col; j < end && read < len; j++)
				buf[read++] = data_poi[j];
			chip->pagebuf = realpage;
		} else
			read += mtd->writesize;

		/* 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);

		if (read == len)
			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 & blockcheck))
			sndcmd = 1;
	}

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

	/*
	 * Return success, if no ECC failures, else -EBADMSG
	 * fs driver will take care of that, because
	 * retlen == desired len and result == -EBADMSG
	 */
	*retlen = read;
	return ecc_failed ? -EBADMSG : 0;
}

/**
 * nand_read_oob - [MTD Interface] NAND read out-of-band
 * @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
 *
 * NAND read out-of-band data from the spare area
 */
static int nand_read_oob(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, uint8_t *buf)
{
	int i, col, page, chipnr;
	struct nand_chip *chip = mtd->priv;
	int blockcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;

	DEBUG(MTD_DEBUG_LEVEL3, "nand_read_oob: from = 0x%08x, len = %i\n", (unsigned int)from, (int)len);

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

	/* Mask to get column */
	col = from & (mtd->oobsize - 1);

	/* Initialize return length value */
	*retlen = 0;

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_read_oob: Attempt read beyond end of device\n");
		*retlen = 0;
		return -EINVAL;
	}

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

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

	/* Send the read command */
	chip->cmdfunc(mtd, NAND_CMD_READOOB, col, page & chip->pagemask);
	/*
	 * Read the data, if we read more than one page
	 * oob data, let the device transfer the data !
	 */
	i = 0;
	while (i < len) {
		int thislen = mtd->oobsize - col;
		thislen = min_t(int, thislen, len);
		chip->read_buf(mtd, &buf[i], thislen);
		i += thislen;

		/* Read more ? */
		if (i < len) {
			page++;
			col = 0;

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

			/* 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);

			/* Check, if the chip supports auto page increment
			 * or if we have hit a block boundary.
			 */
			if (!NAND_CANAUTOINCR(chip) || !(page & blockcheck)) {
				/* For subsequent page reads set offset to 0 */
				chip->cmdfunc(mtd, NAND_CMD_READOOB, 0x0, page & chip->pagemask);
			}
		}
	}

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

	/* Return happy */
	*retlen = len;
	return 0;
}

/**
 * nand_read_raw - [GENERIC] Read raw data including oob into buffer
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @ooblen:	number of oob data bytes to read
 *
 * Read raw data including oob into buffer
 */
int nand_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t from, size_t len,
		  size_t ooblen)
{
	struct nand_chip *chip = mtd->priv;
	int page = (int)(from >> chip->page_shift);
	int chipnr = (int)(from >> chip->chip_shift);
	int sndcmd = 1;
	int cnt = 0;
	int pagesize = mtd->writesize + mtd->oobsize;
	int blockcheck;

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

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

	chip->select_chip(mtd, chipnr);

	/* Add requested oob length */
	len += ooblen;
	blockcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;

	while (len) {
		if (sndcmd)
			chip->cmdfunc(mtd, NAND_CMD_READ0, 0,
				      page & chip->pagemask);
		sndcmd = 0;

		chip->read_buf(mtd, &buf[cnt], pagesize);

		len -= pagesize;
		cnt += pagesize;
		page++;

		if (!chip->dev_ready)
			udelay(chip->chip_delay);
		else
			nand_wait_ready(mtd);

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

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);
	return 0;
}

/**
 * nand_write_raw - [GENERIC] Write raw data including oob
 * @mtd:	MTD device structure
 * @buf:	source buffer
 * @to:		offset to write to
 * @len:	number of bytes to write
 * @buf:	source buffer
 * @oob:	oob buffer
 *
 * Write raw data including oob
 */
int nand_write_raw(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
		   uint8_t *buf, uint8_t *oob)
{
	struct nand_chip *chip = mtd->priv;
	int page = (int)(to >> chip->page_shift);
	int chipnr = (int)(to >> chip->chip_shift);
	int ret;

	*retlen = 0;

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

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

	chip->select_chip(mtd, chipnr);
	chip->data_poi = buf;

	while (len != *retlen) {
		ret = nand_write_page(mtd, chip, page, oob, &mtd->oobinfo, 0);
		if (ret)
			return ret;
		page++;
		*retlen += mtd->writesize;
		chip->data_poi += mtd->writesize;
		oob += mtd->oobsize;
	}

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);
	return 0;
}
EXPORT_SYMBOL_GPL(nand_write_raw);

/**
 * nand_prepare_oobbuf - [GENERIC] Prepare the out of band buffer
 * @mtd:	MTD device structure
 * @fsbuf:	buffer given by fs driver
 * @oobsel:	out of band selection structre
 * @autoplace:	1 = place given buffer into the oob bytes
 * @numpages:	number of pages to prepare
 *
 * Return:
 * 1. Filesystem buffer available and autoplacement is off,
 *    return filesystem buffer
 * 2. No filesystem buffer or autoplace is off, return internal
 *    buffer
 * 3. Filesystem buffer is given and autoplace selected
 *    put data from fs buffer into internal buffer and
 *    retrun internal buffer
 *
 * Note: The internal buffer is filled with 0xff. This must
 * be done only once, when no autoplacement happens
 * Autoplacement sets the buffer dirty flag, which
 * forces the 0xff fill before using the buffer again.
 *
*/
static uint8_t *nand_prepare_oobbuf(struct mtd_info *mtd, uint8_t *fsbuf, struct nand_oobinfo *oobsel,
				   int autoplace, int numpages)
{
	struct nand_chip *chip = mtd->priv;
	int i, len, ofs;

	/* Zero copy fs supplied buffer */
	if (fsbuf && !autoplace)
		return fsbuf;

	/* Check, if the buffer must be filled with ff again */
	if (chip->oobdirty) {
		memset(chip->oob_buf, 0xff, mtd->oobsize << (chip->phys_erase_shift - chip->page_shift));
		chip->oobdirty = 0;
	}

	/* If we have no autoplacement or no fs buffer use the internal one */
	if (!autoplace || !fsbuf)
		return chip->oob_buf;

	/* Walk through the pages and place the data */
	chip->oobdirty = 1;
	ofs = 0;
	while (numpages--) {
		for (i = 0, len = 0; len < mtd->oobavail; i++) {
			int to = ofs + oobsel->oobfree[i][0];
			int num = oobsel->oobfree[i][1];
			memcpy(&chip->oob_buf[to], fsbuf, num);
			len += num;
			fsbuf += num;
		}
		ofs += mtd->oobavail;
	}
	return chip->oob_buf;
}

#define NOTALIGNED(x) (x & (mtd->writesize-1)) != 0

/**
 * 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)
{
	int startpage, page, ret = -EIO, oob = 0, written = 0, chipnr;
	int autoplace = 0, numpages, totalpages;
	struct nand_chip *chip = mtd->priv;
	uint8_t *oobbuf, *bufstart, *eccbuf = NULL;
	int ppblock = (1 << (chip->phys_erase_shift - chip->page_shift));
	struct nand_oobinfo *oobsel = &mtd->oobinfo;

	DEBUG(MTD_DEBUG_LEVEL3, "nand_write: to = 0x%08x, len = %i\n", (unsigned int)to, (int)len);

	/* Initialize retlen, in case of early exit */
	*retlen = 0;

	/* Do not allow write past end of device */
	if ((to + len) > mtd->size) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_write: Attempt to write past end of page\n");
		return -EINVAL;
	}

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

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

	/* Calculate chipnr */
	chipnr = (int)(to >> chip->chip_shift);
	/* Select the NAND device */
	chip->select_chip(mtd, chipnr);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		goto out;

	/* Autoplace of oob data ? Use the default placement scheme */
	if (oobsel->useecc == MTD_NANDECC_AUTOPLACE) {
		oobsel = chip->autooob;
		autoplace = 1;
	}
	if (oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
		autoplace = 1;

	/* Setup variables and oob buffer */
	totalpages = len >> chip->page_shift;
	page = (int)(to >> chip->page_shift);
	/* Invalidate the page cache, if we write to the cached page */
	if (page <= chip->pagebuf && chip->pagebuf < (page + totalpages))
		chip->pagebuf = -1;

	/* Set it relative to chip */
	page &= chip->pagemask;
	startpage = page;
	/* Calc number of pages we can write in one go */
	numpages = min(ppblock - (startpage & (ppblock - 1)), totalpages);
	oobbuf = nand_prepare_oobbuf(mtd, eccbuf, oobsel, autoplace, numpages);
	bufstart = (uint8_t *) buf;

	/* Loop until all data is written */
	while (written < len) {

		chip->data_poi = (uint8_t *) &buf[written];
		/* Write one page. If this is the last page to write
		 * or the last page in this block, then use the
		 * real pageprogram command, else select cached programming
		 * if supported by the chip.
		 */
		ret = nand_write_page(mtd, chip, page, &oobbuf[oob], oobsel, (--numpages > 0));
		if (ret) {
			DEBUG(MTD_DEBUG_LEVEL0, "nand_write: write_page failed %d\n", ret);
			goto out;
		}
		/* Next oob page */
		oob += mtd->oobsize;
		/* Update written bytes count */
		written += mtd->writesize;
		if (written == len)
			goto cmp;

		/* Increment page address */
		page++;

		/* Have we hit a block boundary ? Then we have to verify and
		 * if verify is ok, we have to setup the oob buffer for
		 * the next pages.
		 */
		if (!(page & (ppblock - 1))) {
			int ofs;
			chip->data_poi = bufstart;
			ret = nand_verify_pages(mtd, this, startpage, page - startpage,
						oobbuf, oobsel, chipnr, (eccbuf != NULL));
			if (ret) {
				DEBUG(MTD_DEBUG_LEVEL0, "nand_write: verify_pages failed %d\n", ret);
				goto out;
			}
			*retlen = written;

			ofs = autoplace ? mtd->oobavail : mtd->oobsize;
			if (eccbuf)
				eccbuf += (page - startpage) * ofs;
			totalpages -= page - startpage;
			numpages = min(totalpages, ppblock);
			page &= chip->pagemask;
			startpage = page;
			oobbuf = nand_prepare_oobbuf(mtd, eccbuf, oobsel, autoplace, numpages);
			oob = 0;
			/* Check, if we cross a chip boundary */
			if (!page) {
				chipnr++;
				chip->select_chip(mtd, -1);
				chip->select_chip(mtd, chipnr);
			}
		}
	}
	/* Verify the remaining pages */
 cmp:
	chip->data_poi = bufstart;
	ret = nand_verify_pages(mtd, this, startpage, totalpages, oobbuf, oobsel, chipnr, (eccbuf != NULL));
	if (!ret)
		*retlen = written;
	else
		DEBUG(MTD_DEBUG_LEVEL0, "nand_write: verify_pages failed %d\n", ret);

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

	return ret;
}

/**
 * nand_write_oob - [MTD Interface] NAND write out-of-band
 * @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 out-of-band
 */
static int nand_write_oob(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const uint8_t *buf)
{
	int column, page, status, ret = -EIO, chipnr;
	struct nand_chip *chip = mtd->priv;

	DEBUG(MTD_DEBUG_LEVEL3, "nand_write_oob: to = 0x%08x, len = %i\n", (unsigned int)to, (int)len);

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

	/* Mask to get column */
	column = to & (mtd->oobsize - 1);

	/* Initialize return length value */
	*retlen = 0;

	/* Do not allow write past end of page */
	if ((column + len) > mtd->oobsize) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_write_oob: Attempt to write past end of page\n");
		return -EINVAL;
	}

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

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

	/* 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))
		goto out;

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

	if (NAND_MUST_PAD(chip)) {
		/* Write out desired data */
		chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page & chip->pagemask);
		/* prepad 0xff for partial programming */
		chip->write_buf(mtd, ffchars, column);
		/* write data */
		chip->write_buf(mtd, buf, len);
		/* postpad 0xff for partial programming */
		chip->write_buf(mtd, ffchars, mtd->oobsize - (len + column));
	} else {
		/* Write out desired data */
		chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize + column, page & chip->pagemask);
		/* write data */
		chip->write_buf(mtd, buf, len);
	}
	/* Send command to program the OOB data */
	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);

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

	/* See if device thinks it succeeded */
	if (status & NAND_STATUS_FAIL) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_write_oob: " "Failed write, page 0x%08x\n", page);
		ret = -EIO;
		goto out;
	}
	/* Return happy */
	*retlen = len;

#ifdef CONFIG_MTD_NAND_VERIFY_WRITE
	/* Send command to read back the data */
	chip->cmdfunc(mtd, NAND_CMD_READOOB, column, page & chip->pagemask);

	if (chip->verify_buf(mtd, buf, len)) {
		DEBUG(MTD_DEBUG_LEVEL0, "nand_write_oob: " "Failed write verify, page 0x%08x\n", page);
		ret = -EIO;
		goto out;
	}
#endif
	ret = 0;
 out:
	/* Deselect and wake up anyone waiting on the device */
	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, len, status, pages_per_block, ret, chipnr;
	struct nand_chip *chip = mtd->priv;
	int rewrite_bbt[NAND_MAX_CHIPS]={0};
	unsigned int bbt_masked_page = 0xffffffff;

	DEBUG(MTD_DEBUG_LEVEL3, "nand_erase: start = 0x%08x, len = %i\n",
	      (unsigned int)instr->addr, (unsigned int)instr->len);

	/* Start address must align on block boundary */
	if (instr->addr & ((1 << chip->phys_erase_shift) - 1)) {
		DEBUG(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)) {
		DEBUG(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) {
		DEBUG(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)) {
		DEBUG(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) {
		/*
		 * 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, FL_ERASING);

		/*
		 * 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, "nand_erase: "
			      "Failed erase, page 0x%08x\n", page);
			instr->state = MTD_ERASE_FAILED;
			instr->fail_addr = (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] = (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;
	/* Do call back function */
	if (!ret)
		mtd_erase_callback(instr);

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

	/*
	 * 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, "nand_erase_nand: nand_update_bbt "
		      "(%d:0x%0x 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;

	DEBUG(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
 * @ofs:	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 "nand_resume() called for a chip which is not "
		       "in suspended state\n");
}

/*
 * Free allocated data structures
 */
static void nand_free_kmem(struct nand_chip *chip)
{
	/* Buffer allocated by nand_scan ? */
	if (chip->options & NAND_OOBBUF_ALLOC)
		kfree(chip->oob_buf);
	/* Buffer allocated by nand_scan ? */
	if (chip->options & NAND_DATABUF_ALLOC)
		kfree(chip->data_buf);
	/* Controller allocated by nand_scan ? */
	if (chip->options & NAND_CONTROLLER_ALLOC)
		kfree(chip->controller);
}

/*
 * Allocate buffers and data structures
 */
static int nand_allocate_kmem(struct mtd_info *mtd, struct nand_chip *chip)
{
	size_t len;

	if (!chip->oob_buf) {
		len = mtd->oobsize <<
			(chip->phys_erase_shift - chip->page_shift);
		chip->oob_buf = kmalloc(len, GFP_KERNEL);
		if (!chip->oob_buf)
			goto outerr;
		chip->options |= NAND_OOBBUF_ALLOC;
	}

	if (!chip->data_buf) {
		len = mtd->writesize + mtd->oobsize;
		chip->data_buf = kmalloc(len, GFP_KERNEL);
		if (!chip->data_buf)
			goto outerr;
		chip->options |= NAND_DATABUF_ALLOC;
	}

	if (!chip->controller) {
		chip->controller = kzalloc(sizeof(struct nand_hw_control),
					   GFP_KERNEL);
		if (!chip->controller)
			goto outerr;
		chip->options |= NAND_CONTROLLER_ALLOC;
	}
	return 0;

 outerr:
	printk(KERN_ERR "nand_scan(): Cannot allocate buffers\n");
	nand_free_kmem(chip);
	return -ENOMEM;
}

/*
 * 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;
}

/*
 * 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;

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

	/* 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);

	/* 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);

	chip->chipsize = nand_flash_ids[i].chipsize << 20;

	/* Newer devices have all the information in additional id bytes */
	if (!nand_flash_ids[i].pagesize) {
		int extid;
		/* The 3rd id byte contains non relevant data ATM */
		extid = 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 = nand_flash_ids[i].erasesize;
		mtd->writesize = nand_flash_ids[i].pagesize;
		mtd->oobsize = mtd->writesize / 32;
		busw = nand_flash_ids[i].options & NAND_BUSWIDTH_16;
	}

	/* Try to identify manufacturer */
	for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_id++) {
		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;
	chip->chip_shift = ffs(chip->chipsize) - 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 |= nand_flash_ids[i].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 && !nand_flash_ids[i].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;
}

/* 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() \
	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. Buffers are allocated if
 * they are not provided by the board driver
 * The mtd->owner field must be set to the module of the caller
 *
 */
int nand_scan(struct mtd_info *mtd, int maxchips)
{
	int i, busw, nand_maf_id;
	struct nand_chip *chip = mtd->priv;
	struct nand_flash_dev *type;

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

	/* 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);
		/* 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;

	/* Allocate buffers and data structures */
	if (nand_allocate_kmem(mtd, chip))
		return -ENOMEM;

	/* Preset the internal oob buffer */
	memset(chip->oob_buf, 0xff,
	       mtd->oobsize << (chip->phys_erase_shift - chip->page_shift));

	/*
	 * If no default placement scheme is given, select an appropriate one
	 */
	if (!chip->autooob) {
		switch (mtd->oobsize) {
		case 8:
			chip->autooob = &nand_oob_8;
			break;
		case 16:
			chip->autooob = &nand_oob_16;
			break;
		case 64:
			chip->autooob = &nand_oob_64;
			break;
		default:
			printk(KERN_WARNING "No oob scheme defined for "
			       "oobsize %d\n", mtd->oobsize);
			BUG();
		}
	}

	/*
	 * The number of bytes available for the filesystem to place fs
	 * dependend oob data
	 */
	mtd->oobavail = 0;
	for (i = 0; chip->autooob->oobfree[i][1]; i++)
		mtd->oobavail += chip->autooob->oobfree[i][1];

	/*
	 * 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:
	case NAND_ECC_HW_SYNDROME:
		if (!chip->ecc.calculate || !chip->ecc.correct ||
		    !chip->ecc.hwctl) {
			printk(KERN_WARNING "No ECC functions supplied, "
			       "Hardware ECC not possible\n");
			BUG();
		}
		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.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.size = mtd->writesize;
		chip->ecc.bytes = 0;
		break;
	default:
		printk(KERN_WARNING "Invalid NAND_ECC_MODE %d\n",
		       chip->ecc.mode);
		BUG();
	}

	/*
	 * 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();
	}

	/* Initialize state, waitqueue and spinlock */
	chip->state = FL_READY;
	init_waitqueue_head(&chip->controller->wq);
	spin_lock_init(&chip->controller->lock);

	/* 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->ecctype = MTD_ECC_SW;
	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;

	/* and make the autooob the default one */
	memcpy(&mtd->oobinfo, chip->autooob, sizeof(mtd->oobinfo));

	/* 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);
}

/**
 * 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
	/* Deregister the device */
	del_mtd_device(mtd);

	/* Free bad block table memory */
	kfree(chip->bbt);
	/* Free buffers */
	nand_free_kmem(chip);
}

EXPORT_SYMBOL_GPL(nand_scan);
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 <sjhill@realitydiluted.com>, Thomas Gleixner <tglx@linutronix.de>");
MODULE_DESCRIPTION("Generic NAND flash driver code");