[MTD] NAND: Honour autoplacement schemes supplied by the caller

[safe/jmp/linux-2.6] / 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 Thomas Gleixner (tglx@linutronix.de)
 *
 *  02-08-2004  tglx: support for strange chips, which cannot auto increment 
 *              pages on read / read_oob
 *
 *  03-17-2004  tglx: Check ready before auto increment check. Simon Bayes
 *              pointed this out, as he marked an auto increment capable chip
 *              as NOAUTOINCR in the board driver.
 *              Make reads over block boundaries work too
 *
 *  04-14-2004  tglx: first working version for 2k page size chips
 *  
 *  05-19-2004  tglx: Basic support for Renesas AG-AND chips
 *
 *  09-24-2004  tglx: add support for hardware controllers (e.g. ECC) shared
 *              among multiple independend devices. Suggestions and initial patch
 *              from Ben Dooks <ben-mtd@fluff.org>
 *
 *  12-05-2004  dmarlin: add workaround for Renesas AG-AND chips "disturb" issue.
 *              Basically, any block not rewritten may lose data when surrounding blocks
 *              are rewritten many times.  JFFS2 ensures this doesn't happen for blocks 
 *              it uses, but the Bad Block Table(s) may not be rewritten.  To ensure they
 *              do not lose data, force them to be rewritten when some of the surrounding
 *              blocks are erased.  Rather than tracking a specific nearby block (which 
 *              could itself go bad), use a page address 'mask' to select several blocks 
 *              in the same area, and rewrite the BBT when any of them are erased.
 *
 *  01-03-2005  dmarlin: added support for the device recovery command sequence for Renesas 
 *              AG-AND chips.  If there was a sudden loss of power during an erase operation,
 *              a "device recovery" operation must be performed when power is restored
 *              to ensure correct operation.
 *
 *  01-20-2005  dmarlin: added support for optional hardware specific callback routine to 
 *              perform extra error status checks on erase and write failures.  This required
 *              adding a wrapper function for nand_read_ecc.
 *
 * 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.
 *
 * $Id: nand_base.c,v 1.143 2005/05/19 16:10:22 gleixner Exp $
 *
 * 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/delay.h>
#include <linux/errno.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 <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 u_char 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 u_char *buf, int len);
static void nand_read_buf(struct mtd_info *mtd, u_char *buf, int len);
static int nand_verify_buf(struct mtd_info *mtd, const u_char *buf, int len);

static int nand_read (struct mtd_info *mtd, loff_t from, size_t len, size_t * retlen, u_char * buf);
static int nand_read_ecc (struct mtd_info *mtd, loff_t from, size_t len,
                          size_t * retlen, u_char * buf, u_char * eccbuf, struct nand_oobinfo *oobsel);
static int nand_read_oob (struct mtd_info *mtd, loff_t from, size_t len, size_t * retlen, u_char * buf);
static int nand_write (struct mtd_info *mtd, loff_t to, size_t len, size_t * retlen, const u_char * buf);
static int nand_write_ecc (struct mtd_info *mtd, loff_t to, size_t len,
                           size_t * retlen, const u_char * buf, u_char * eccbuf, struct nand_oobinfo *oobsel);
static int nand_write_oob (struct mtd_info *mtd, loff_t to, size_t len, size_t * retlen, const u_char *buf);
static int nand_writev (struct mtd_info *mtd, const struct kvec *vecs,
                        unsigned long count, loff_t to, size_t * retlen);
static int nand_writev_ecc (struct mtd_info *mtd, const struct kvec *vecs,
                        unsigned long count, loff_t to, size_t * retlen, u_char *eccbuf, struct nand_oobinfo *oobsel);
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 *this, int page, u_char *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 *this, int page, int numpages, 
        u_char *oob_buf, struct nand_oobinfo *oobsel, int chipnr, int oobmode);
#else
#define nand_verify_pages(...) (0)
#endif
                
static void nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state);

/**
 * 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;

        /* De-select the NAND device */
        this->select_chip(mtd, -1);
        /* Do we have a hardware controller ? */
        if (this->controller) {
                spin_lock(&this->controller->lock);
                this->controller->active = NULL;
                spin_unlock(&this->controller->lock);
        }
        /* Release the chip */
        spin_lock (&this->chip_lock);
        this->state = FL_READY;
        wake_up (&this->wq);
        spin_unlock (&this->chip_lock);
}

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

/**
 * nand_write_byte - [DEFAULT] write one byte to the chip
 * @mtd:        MTD device structure
 * @byte:       pointer to data byte to write
 *
 * Default write function for 8it buswith
 */
static void nand_write_byte(struct mtd_info *mtd, u_char byte)
{
        struct nand_chip *this = mtd->priv;
        writeb(byte, this->IO_ADDR_W);
}

/**
 * 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 u_char nand_read_byte16(struct mtd_info *mtd)
{
        struct nand_chip *this = mtd->priv;
        return (u_char) cpu_to_le16(readw(this->IO_ADDR_R));
}

/**
 * nand_write_byte16 - [DEFAULT] write one byte endianess aware to the chip
 * @mtd:        MTD device structure
 * @byte:       pointer to data byte to write
 *
 * Default write function for 16bit buswith with
 * endianess conversion
 */
static void nand_write_byte16(struct mtd_info *mtd, u_char byte)
{
        struct nand_chip *this = mtd->priv;
        writew(le16_to_cpu((u16) byte), this->IO_ADDR_W);
}

/**
 * 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 *this = mtd->priv;
        return readw(this->IO_ADDR_R);
}

/**
 * nand_write_word - [DEFAULT] write one word to the chip
 * @mtd:        MTD device structure
 * @word:       data word to write
 *
 * Default write function for 16bit buswith without 
 * endianess conversion
 */
static void nand_write_word(struct mtd_info *mtd, u16 word)
{
        struct nand_chip *this = mtd->priv;
        writew(word, this->IO_ADDR_W);
}

/**
 * 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 chip)
{
        struct nand_chip *this = mtd->priv;
        switch(chip) {
        case -1:
                this->hwcontrol(mtd, NAND_CTL_CLRNCE);  
                break;
        case 0:
                this->hwcontrol(mtd, NAND_CTL_SETNCE);
                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 u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;

        for (i=0; i<len; i++)
                writeb(buf[i], this->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, u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;

        for (i=0; i<len; i++)
                buf[i] = readb(this->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 u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;

        for (i=0; i<len; i++)
                if (buf[i] != readb(this->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 u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;
        u16 *p = (u16 *) buf;
        len >>= 1;
        
        for (i=0; i<len; i++)
                writew(p[i], this->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, u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;
        u16 *p = (u16 *) buf;
        len >>= 1;

        for (i=0; i<len; i++)
                p[i] = readw(this->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 u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd->priv;
        u16 *p = (u16 *) buf;
        len >>= 1;

        for (i=0; i<len; i++)
                if (p[i] != readw(this->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 *this = mtd->priv;
        u16 bad;

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

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

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

        if (this->options & NAND_BUSWIDTH_16) {
                this->cmdfunc (mtd, NAND_CMD_READOOB, this->badblockpos & 0xFE, page & this->pagemask);
                bad = cpu_to_le16(this->read_word(mtd));
                if (this->badblockpos & 0x1)
                        bad >>= 1;
                if ((bad & 0xFF) != 0xff)
                        res = 1;
        } else {
                this->cmdfunc (mtd, NAND_CMD_READOOB, this->badblockpos, page & this->pagemask);
                if (this->read_byte(mtd) != 0xff)
                        res = 1;
        }
                
        if (getchip) {
                /* Deselect and wake up anyone waiting on the device */
                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 *this = mtd->priv;
        u_char buf[2] = {0, 0};
        size_t  retlen;
        int block;
        
        /* Get block number */
        block = ((int) ofs) >> this->bbt_erase_shift;
        if (this->bbt)
                this->bbt[block >> 2] |= 0x01 << ((block & 0x03) << 1);

        /* Do we have a flash based bad block table ? */
        if (this->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 + (this->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 *this = mtd->priv;
        /* Check the WP bit */
        this->cmdfunc (mtd, NAND_CMD_STATUS, -1, -1);
        return (this->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 *this = mtd->priv;
        
        if (!this->bbt)
                return this->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 *this = mtd->priv;
        unsigned long   timeo = jiffies + 2;

        /* wait until command is processed or timeout occures */
        do {
                if (this->dev_ready(mtd))
                        return;
        } while (time_before(jiffies, timeo));  
}

/**
 * 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 command, int column, int page_addr)
{
        register struct nand_chip *this = mtd->priv;

        /* Begin command latch cycle */
        this->hwcontrol(mtd, NAND_CTL_SETCLE);
        /*
         * Write out the command to the device.
         */
        if (command == NAND_CMD_SEQIN) {
                int readcmd;

                if (column >= mtd->oobblock) {
                        /* OOB area */
                        column -= mtd->oobblock;
                        readcmd = NAND_CMD_READOOB;
                } else if (column < 256) {
                        /* First 256 bytes --> READ0 */
                        readcmd = NAND_CMD_READ0;
                } else {
                        column -= 256;
                        readcmd = NAND_CMD_READ1;
                }
                this->write_byte(mtd, readcmd);
        }
        this->write_byte(mtd, command);

        /* Set ALE and clear CLE to start address cycle */
        this->hwcontrol(mtd, NAND_CTL_CLRCLE);

        if (column != -1 || page_addr != -1) {
                this->hwcontrol(mtd, NAND_CTL_SETALE);

                /* Serially input address */
                if (column != -1) {
                        /* Adjust columns for 16 bit buswidth */
                        if (this->options & NAND_BUSWIDTH_16)
                                column >>= 1;
                        this->write_byte(mtd, column);
                }
                if (page_addr != -1) {
                        this->write_byte(mtd, (unsigned char) (page_addr & 0xff));
                        this->write_byte(mtd, (unsigned char) ((page_addr >> 8) & 0xff));
                        /* One more address cycle for devices > 32MiB */
                        if (this->chipsize > (32 << 20))
                                this->write_byte(mtd, (unsigned char) ((page_addr >> 16) & 0x0f));
                }
                /* Latch in address */
                this->hwcontrol(mtd, NAND_CTL_CLRALE);
        }
        
        /* 
         * 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 (this->dev_ready)    
                        break;
                udelay(this->chip_delay);
                this->hwcontrol(mtd, NAND_CTL_SETCLE);
                this->write_byte(mtd, NAND_CMD_STATUS);
                this->hwcontrol(mtd, NAND_CTL_CLRCLE);
                while ( !(this->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 (!this->dev_ready) {
                        udelay (this->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 seperate 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 command, int column, int page_addr)
{
        register struct nand_chip *this = mtd->priv;

        /* Emulate NAND_CMD_READOOB */
        if (command == NAND_CMD_READOOB) {
                column += mtd->oobblock;
                command = NAND_CMD_READ0;
        }
        
                
        /* Begin command latch cycle */
        this->hwcontrol(mtd, NAND_CTL_SETCLE);
        /* Write out the command to the device. */
        this->write_byte(mtd, (command & 0xff));
        /* End command latch cycle */
        this->hwcontrol(mtd, NAND_CTL_CLRCLE);

        if (column != -1 || page_addr != -1) {
                this->hwcontrol(mtd, NAND_CTL_SETALE);

                /* Serially input address */
                if (column != -1) {
                        /* Adjust columns for 16 bit buswidth */
                        if (this->options & NAND_BUSWIDTH_16)
                                column >>= 1;
                        this->write_byte(mtd, column & 0xff);
                        this->write_byte(mtd, column >> 8);
                }       
                if (page_addr != -1) {
                        this->write_byte(mtd, (unsigned char) (page_addr & 0xff));
                        this->write_byte(mtd, (unsigned char) ((page_addr >> 8) & 0xff));
                        /* One more address cycle for devices > 128MiB */
                        if (this->chipsize > (128 << 20))
                                this->write_byte(mtd, (unsigned char) ((page_addr >> 16) & 0xff));
                }
                /* Latch in address */
                this->hwcontrol(mtd, NAND_CTL_CLRALE);
        }
        
        /* 
         * 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(this->chip_delay);
                return;

        case NAND_CMD_RESET:
                if (this->dev_ready)    
                        break;
                udelay(this->chip_delay);
                this->hwcontrol(mtd, NAND_CTL_SETCLE);
                this->write_byte(mtd, NAND_CMD_STATUS);
                this->hwcontrol(mtd, NAND_CTL_CLRCLE);
                while ( !(this->read_byte(mtd) & NAND_STATUS_READY));
                return;

        case NAND_CMD_READ0:
                /* Begin command latch cycle */
                this->hwcontrol(mtd, NAND_CTL_SETCLE);
                /* Write out the start read command */
                this->write_byte(mtd, NAND_CMD_READSTART);
                /* End command latch cycle */
                this->hwcontrol(mtd, NAND_CTL_CLRCLE);
                /* Fall through into ready check */
                
        /* This applies to read commands */     
        default:
                /* 
                 * If we don't have access to the busy pin, we apply the given
                 * command delay
                */
                if (!this->dev_ready) {
                        udelay (this->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 void nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state)
{
        struct nand_chip *active = this;

        DECLARE_WAITQUEUE (wait, current);

        /* 
         * Grab the lock and see if the device is available 
        */
retry:
        /* Hardware controller shared among independend devices */
        if (this->controller) {
                spin_lock (&this->controller->lock);
                if (this->controller->active)
                        active = this->controller->active;
                else
                        this->controller->active = this;
                spin_unlock (&this->controller->lock);
        }
        
        if (active == this) {
                spin_lock (&this->chip_lock);
                if (this->state == FL_READY) {
                        this->state = new_state;
                        spin_unlock (&this->chip_lock);
                        return;
                }
        }       
        set_current_state (TASK_UNINTERRUPTIBLE);
        add_wait_queue (&active->wq, &wait);
        spin_unlock (&active->chip_lock);
        schedule ();
        remove_wait_queue (&active->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 *this, int state)
{

        unsigned long   timeo = jiffies;
        int     status;
        
        if (state == FL_ERASING)
                 timeo += (HZ * 400) / 1000;
        else
                 timeo += (HZ * 20) / 1000;

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

        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);

        while (time_before(jiffies, timeo)) {           
                /* Check, if we were interrupted */
                if (this->state != state)
                        return 0;

                if (this->dev_ready) {
                        if (this->dev_ready(mtd))
                                break;  
                } else {
                        if (this->read_byte(mtd) & NAND_STATUS_READY)
                                break;
                }
                cond_resched();
        }
        status = (int) this->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 & this->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 *this, int page, 
        u_char *oob_buf,  struct nand_oobinfo *oobsel, int cached)
{
        int     i, status;
        u_char  ecc_code[32];
        int     eccmode = oobsel->useecc ? this->eccmode : NAND_ECC_NONE;
        int     *oob_config = oobsel->eccpos;
        int     datidx = 0, eccidx = 0, eccsteps = this->eccsteps;
        int     eccbytes = 0;
        
        /* FIXME: Enable cached programming */
        cached = 0;
        
        /* Send command to begin auto page programming */
        this->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");
                this->write_buf(mtd, this->data_poi, mtd->oobblock);
                break;
                
        /* Software ecc 3/256, write all */
        case NAND_ECC_SOFT:
                for (; eccsteps; eccsteps--) {
                        this->calculate_ecc(mtd, &this->data_poi[datidx], ecc_code);
                        for (i = 0; i < 3; i++, eccidx++)
                                oob_buf[oob_config[eccidx]] = ecc_code[i];
                        datidx += this->eccsize;
                }
                this->write_buf(mtd, this->data_poi, mtd->oobblock);
                break;
        default:
                eccbytes = this->eccbytes;
                for (; eccsteps; eccsteps--) {
                        /* enable hardware ecc logic for write */
                        this->enable_hwecc(mtd, NAND_ECC_WRITE);
                        this->write_buf(mtd, &this->data_poi[datidx], this->eccsize);
                        this->calculate_ecc(mtd, &this->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 (this->options & NAND_HWECC_SYNDROME)
                                this->write_buf(mtd, ecc_code, eccbytes);
                        datidx += this->eccsize;
                }
                break;
        }
                                                                                
        /* Write out OOB data */
        if (this->options & NAND_HWECC_SYNDROME)
                this->write_buf(mtd, &oob_buf[oobsel->eccbytes], mtd->oobsize - oobsel->eccbytes);
        else 
                this->write_buf(mtd, oob_buf, mtd->oobsize);

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

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

                /* See if operation failed and additional status checks are available */
                if ((status & NAND_STATUS_FAIL) && (this->errstat)) {
                        status = this->errstat(mtd, this, 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 = this->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 & this->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 *this, int page, int numpages, 
        u_char *oob_buf, struct nand_oobinfo *oobsel, int chipnr, int oobmode)
{
        int     i, j, datidx = 0, oobofs = 0, res = -EIO;
        int     eccsteps = this->eccsteps;
        int     hweccbytes; 
        u_char  oobdata[64];

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

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

        for(;;) {
                for (j = 0; j < eccsteps; j++) {
                        /* Loop through and verify the data */
                        if (this->verify_buf(mtd, &this->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 (this->verify_buf(mtd, &this->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 (this->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 */
                        this->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 (!this->dev_ready) 
                        udelay (this->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))
                        this->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:     
        this->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, u_char * buf)
{
        return nand_do_read_ecc (mtd, from, len, retlen, buf, NULL, &mtd->oobinfo, 0xff);
}


/**
 * nand_read_ecc - [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
 * @oob_buf:    filesystem supplied oob data buffer
 * @oobsel:     oob selection structure
 *
 * This function simply calls nand_do_read_ecc with flags = 0xff
 */
static int nand_read_ecc (struct mtd_info *mtd, loff_t from, size_t len,
                          size_t * retlen, u_char * buf, u_char * oob_buf, struct nand_oobinfo *oobsel)
{
        /* use userspace supplied oobinfo, if zero */
        if (oobsel == NULL)
                oobsel = &mtd->oobinfo;
        return nand_do_read_ecc(mtd, from, len, retlen, buf, oob_buf, oobsel, 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, u_char * buf, u_char * 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 *this = mtd->priv;
        u_char *data_poi, *oob_data = oob_buf;
        u_char ecc_calc[32];
        u_char ecc_code[32];
        int eccmode, eccsteps;
        int     *oob_config, datidx;
        int     blockcheck = (1 << (this->phys_erase_shift - this->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 (this, mtd, FL_READING);

        /* Autoplace of oob data ? Use the default placement scheme */
        if (oobsel->useecc == MTD_NANDECC_AUTOPLACE)
                oobsel = this->autooob;
                
        eccmode = oobsel->useecc ? this->eccmode : NAND_ECC_NONE;
        oob_config = oobsel->eccpos;

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

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

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

        end = mtd->oobblock;
        ecc = this->eccsize;
        eccbytes = this->eccbytes;
        
        if ((eccmode == NAND_ECC_NONE) || (this->options & NAND_HWECC_SYNDROME))
                compareecc = 0;

        oobreadlen = mtd->oobsize;
        if (this->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 = this->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 == this->pagebuf && !oob_buf) {
                        /* aligned read ? */
                        if (aligned)
                                memcpy (data_poi, this->data_buf, end);
                        goto readdata;
                }

                /* Check, if we must send the read command */
                if (sndcmd) {
                        this->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 = &this->data_buf[end];

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

                default:
                        for (i = 0, datidx = 0; eccsteps; eccsteps--, i+=eccbytes, datidx += ecc) {
                                this->enable_hwecc(mtd, NAND_ECC_READ);
                                this->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 */
                                        this->enable_hwecc(mtd, NAND_ECC_READSYN);
                                        this->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 = this->correct_data(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 {
                                        this->calculate_ecc(mtd, &data_poi[datidx], &ecc_calc[i]);
                                }       
                        }
                        break;                                          
                }

                /* read oobdata */
                this->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 neccecary */
                for (i = 0, j = 0, datidx = 0; i < this->eccsteps; i++, datidx += ecc) {
                        ecc_status = this->correct_data(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 += this->eccsteps * 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];
                        this->pagebuf = realpage;       
                } else          
                        read += mtd->oobblock;

                /* 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 (!this->dev_ready) 
                        udelay (this->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 & this->pagemask;
                /* Check, if we cross a chip boundary */
                if (!page) {
                        chipnr++;
                        this->select_chip(mtd, -1);
                        this->select_chip(mtd, chipnr);
                }
                /* Check, if the chip supports auto page increment 
                 * or if we have hit a block boundary. 
                */ 
                if (!NAND_CANAUTOINCR(this) || !(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, u_char * buf)
{
        int i, col, page, chipnr;
        struct nand_chip *this = mtd->priv;
        int     blockcheck = (1 << (this->phys_erase_shift - this->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 >> this->page_shift);
        chipnr = (int)(from >> this->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 (this, mtd , FL_READING);

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

        /* Send the read command */
        this->cmdfunc (mtd, NAND_CMD_READOOB, col, page & this->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);
                this->read_buf(mtd, &buf[i], thislen);
                i += thislen;
                
                /* 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 (!this->dev_ready) 
                        udelay (this->chip_delay);
                else
                        nand_wait_ready(mtd);

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

                        /* Check, if we cross a chip boundary */
                        if (!(page & this->pagemask)) {
                                chipnr++;
                                this->select_chip(mtd, -1);
                                this->select_chip(mtd, chipnr);
                        }
                                
                        /* Check, if the chip supports auto page increment 
                         * or if we have hit a block boundary. 
                        */ 
                        if (!NAND_CANAUTOINCR(this) || !(page & blockcheck)) {
                                /* For subsequent page reads set offset to 0 */
                                this->cmdfunc (mtd, NAND_CMD_READOOB, 0x0, page & this->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 *this = mtd->priv;
        int page = (int) (from >> this->page_shift);
        int chip = (int) (from >> this->chip_shift);
        int sndcmd = 1;
        int cnt = 0;
        int pagesize = mtd->oobblock + mtd->oobsize;
        int     blockcheck = (1 << (this->phys_erase_shift - this->page_shift)) - 1;

        /* 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 (this, mtd , FL_READING);

        this->select_chip (mtd, chip);
        
        /* Add requested oob length */
        len += ooblen;
        
        while (len) {
                if (sndcmd)
                        this->cmdfunc (mtd, NAND_CMD_READ0, 0, page & this->pagemask);
                sndcmd = 0;     

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

                len -= pagesize;
                cnt += pagesize;
                page++;
                
                if (!this->dev_ready) 
                        udelay (this->chip_delay);
                else
                        nand_wait_ready(mtd);
                        
                /* Check, if the chip supports auto page increment */ 
                if (!NAND_CANAUTOINCR(this) || !(page & blockcheck))
                        sndcmd = 1;
        }

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


/** 
 * 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 u_char * nand_prepare_oobbuf (struct mtd_info *mtd, u_char *fsbuf, struct nand_oobinfo *oobsel,
                int autoplace, int numpages)
{
        struct nand_chip *this = 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 (this->oobdirty) {   
                memset (this->oob_buf, 0xff, 
                        mtd->oobsize << (this->phys_erase_shift - this->page_shift));
                this->oobdirty = 0;
        }       
        
        /* If we have no autoplacement or no fs buffer use the internal one */
        if (!autoplace || !fsbuf)
                return this->oob_buf;
        
        /* Walk through the pages and place the data */
        this->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 (&this->oob_buf[to], fsbuf, num);
                        len += num;
                        fsbuf += num;
                }
                ofs += mtd->oobavail;
        }
        return this->oob_buf;
}

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

/**
 * nand_write - [MTD Interface] compability function for nand_write_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
 *
 * This function simply calls nand_write_ecc with oob buffer and oobsel = NULL
 *
*/
static int nand_write (struct mtd_info *mtd, loff_t to, size_t len, size_t * retlen, const u_char * buf)
{
        return (nand_write_ecc (mtd, to, len, retlen, buf, NULL, NULL));
}
                           
/**
 * nand_write_ecc - [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
 * @eccbuf:     filesystem supplied oob data buffer
 * @oobsel:     oob selection structure
 *
 * NAND write with ECC
 */
static int nand_write_ecc (struct mtd_info *mtd, loff_t to, size_t len,
                           size_t * retlen, const u_char * buf, u_char * eccbuf, struct nand_oobinfo *oobsel)
{
        int startpage, page, ret = -EIO, oob = 0, written = 0, chipnr;
        int autoplace = 0, numpages, totalpages;
        struct nand_chip *this = mtd->priv;
        u_char *oobbuf, *bufstart;
        int     ppblock = (1 << (this->phys_erase_shift - this->page_shift));

        DEBUG (MTD_DEBUG_LEVEL3, "nand_write_ecc: 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_ecc: 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_ecc: Attempt to write not page aligned data\n");
                return -EINVAL;
        }

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

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

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

        /* if oobsel is NULL, use chip defaults */
        if (oobsel == NULL) 
                oobsel = &mtd->oobinfo;         
                
        /* Autoplace of oob data ? Use the default placement scheme */
        if (oobsel->useecc == MTD_NANDECC_AUTOPLACE) {
                oobsel = this->autooob;
                autoplace = 1;
        }       
        if (oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
                autoplace = 1;

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

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

                this->data_poi = (u_char*) &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, this, page, &oobbuf[oob], oobsel, (--numpages > 0));
                if (ret) {
                        DEBUG (MTD_DEBUG_LEVEL0, "nand_write_ecc: write_page failed %d\n", ret);
                        goto out;
                }       
                /* Next oob page */
                oob += mtd->oobsize;
                /* Update written bytes count */
                written += mtd->oobblock;
                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;
                        this->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_ecc: 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 &= this->pagemask;
                        startpage = page;
                        oobbuf = nand_prepare_oobbuf (mtd, eccbuf, oobsel, 
                                        autoplace, numpages);
                        /* Check, if we cross a chip boundary */
                        if (!page) {
                                chipnr++;
                                this->select_chip(mtd, -1);
                                this->select_chip(mtd, chipnr);
                        }
                }
        }
        /* Verify the remaining pages */
cmp:
        this->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_ecc: 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 u_char * buf)
{
        int column, page, status, ret = -EIO, chipnr;
        struct nand_chip *this = 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 >> this->page_shift);
        chipnr = (int) (to >> this->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 (this, mtd, FL_WRITING);

        /* Select the NAND device */
        this->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. */
        this->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 == this->pagebuf)
                this->pagebuf = -1;

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

        status = this->waitfunc (mtd, this, 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 */
        this->cmdfunc (mtd, NAND_CMD_READOOB, column, page & this->pagemask);

        if (this->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;
}


/**
 * nand_writev - [MTD Interface] compabilty function for nand_writev_ecc
 * @mtd:        MTD device structure
 * @vecs:       the iovectors to write
 * @count:      number of vectors
 * @to:         offset to write to
 * @retlen:     pointer to variable to store the number of written bytes
 *
 * NAND write with kvec. This just calls the ecc function
 */
static int nand_writev (struct mtd_info *mtd, const struct kvec *vecs, unsigned long count, 
                loff_t to, size_t * retlen)
{
        return (nand_writev_ecc (mtd, vecs, count, to, retlen, NULL, NULL));    
}

/**
 * nand_writev_ecc - [MTD Interface] write with iovec with ecc
 * @mtd:        MTD device structure
 * @vecs:       the iovectors to write
 * @count:      number of vectors
 * @to:         offset to write to
 * @retlen:     pointer to variable to store the number of written bytes
 * @eccbuf:     filesystem supplied oob data buffer
 * @oobsel:     oob selection structure
 *
 * NAND write with iovec with ecc
 */
static int nand_writev_ecc (struct mtd_info *mtd, const struct kvec *vecs, unsigned long count, 
                loff_t to, size_t * retlen, u_char *eccbuf, struct nand_oobinfo *oobsel)
{
        int i, page, len, total_len, ret = -EIO, written = 0, chipnr;
        int oob, numpages, autoplace = 0, startpage;
        struct nand_chip *this = mtd->priv;
        int     ppblock = (1 << (this->phys_erase_shift - this->page_shift));
        u_char *oobbuf, *bufstart;

        /* Preset written len for early exit */
        *retlen = 0;

        /* Calculate total length of data */
        total_len = 0;
        for (i = 0; i < count; i++)
                total_len += (int) vecs[i].iov_len;

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

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

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

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

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

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

        /* if oobsel is NULL, use chip defaults */
        if (oobsel == NULL) 
                oobsel = &mtd->oobinfo;         

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

        /* Setup start page */
        page = (int) (to >> this->page_shift);
        /* Invalidate the page cache, if we write to the cached page */
        if (page <= this->pagebuf && this->pagebuf < ((to + total_len) >> this->page_shift))  
                this->pagebuf = -1;

        startpage = page & this->pagemask;

        /* Loop until all kvec' data has been written */
        len = 0;
        while (count) {
                /* If the given tuple is >= pagesize then
                 * write it out from the iov
                 */
                if ((vecs->iov_len - len) >= mtd->oobblock) {
                        /* Calc number of pages we can write
                         * out of this iov in one go */
                        numpages = (vecs->iov_len - len) >> this->page_shift;
                        /* Do not cross block boundaries */
                        numpages = min (ppblock - (startpage & (ppblock - 1)), numpages);
                        oobbuf = nand_prepare_oobbuf (mtd, NULL, oobsel, autoplace, numpages);
                        bufstart = (u_char *)vecs->iov_base;
                        bufstart += len;
                        this->data_poi = bufstart;
                        oob = 0;
                        for (i = 1; i <= numpages; i++) {
                                /* Write one page. If this is the last page to write
                                 * then use the real pageprogram command, else select 
                                 * cached programming if supported by the chip.
                                 */
                                ret = nand_write_page (mtd, this, page & this->pagemask, 
                                        &oobbuf[oob], oobsel, i != numpages);
                                if (ret)
                                        goto out;
                                this->data_poi += mtd->oobblock;
                                len += mtd->oobblock;
                                oob += mtd->oobsize;
                                page++;
                        }
                        /* Check, if we have to switch to the next tuple */
                        if (len >= (int) vecs->iov_len) {
                                vecs++;
                                len = 0;
                                count--;
                        }
                } else {
                        /* We must use the internal buffer, read data out of each 
                         * tuple until we have a full page to write
                         */
                        int cnt = 0;
                        while (cnt < mtd->oobblock) {
                                if (vecs->iov_base != NULL && vecs->iov_len) 
                                        this->data_buf[cnt++] = ((u_char *) vecs->iov_base)[len++];
                                /* Check, if we have to switch to the next tuple */
                                if (len >= (int) vecs->iov_len) {
                                        vecs++;
                                        len = 0;
                                        count--;
                                }
                        }
                        this->pagebuf = page;   
                        this->data_poi = this->data_buf;        
                        bufstart = this->data_poi;
                        numpages = 1;           
                        oobbuf = nand_prepare_oobbuf (mtd, NULL, oobsel, autoplace, numpages);
                        ret = nand_write_page (mtd, this, page & this->pagemask,
                                oobbuf, oobsel, 0);
                        if (ret)
                                goto out;
                        page++;
                }

                this->data_poi = bufstart;
                ret = nand_verify_pages (mtd, this, startpage, numpages, oobbuf, oobsel, chipnr, 0);
                if (ret)
                        goto out;
                        
                written += mtd->oobblock * numpages;
                /* All done ? */
                if (!count)
                        break;

                startpage = page & this->pagemask;
                /* Check, if we cross a chip boundary */
                if (!startpage) {
                        chipnr++;
                        this->select_chip(mtd, -1);
                        this->select_chip(mtd, chipnr);
                }
        }
        ret = 0;
out:
        /* Deselect and wake up anyone waiting on the device */
        nand_release_device(mtd);

        *retlen = written;
        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 *this = mtd->priv;
        /* Send commands to erase a block */
        this->cmdfunc (mtd, NAND_CMD_ERASE1, -1, page);
        this->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 *this = mtd->priv;
        /* Send commands to erase a block */
        this->cmdfunc (mtd, NAND_CMD_ERASE1, -1, page++);
        this->cmdfunc (mtd, NAND_CMD_ERASE1, -1, page++);
        this->cmdfunc (mtd, NAND_CMD_ERASE1, -1, page++);
        this->cmdfunc (mtd, NAND_CMD_ERASE1, -1, page);
        this->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_intern - [NAND Interface] 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 *this = mtd->priv;
        int rewrite_bbt[NAND_MAX_CHIPS]={0};    /* flags to indicate the page, if bbt needs to be rewritten. */
        unsigned int bbt_masked_page;           /* bbt mask to compare to page being erased. */
                                                /* It is used to see if the current page is in the same */
                                                /*   256 block group and the same bank as the bbt. */

        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 << this->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 << this->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 (this, mtd, FL_ERASING);

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

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

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

        /* Check the WP bit */
        /* 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 */
        if (this->options & BBT_AUTO_REFRESH) {
                bbt_masked_page = this->bbt_td->pages[chipnr] & BBT_PAGE_MASK;
        } else {
                bbt_masked_page = 0xffffffff;   /* should not match anything */
        }

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

        instr->state = MTD_ERASING;

        while (len) {
                /* Check if we have a bad block, we do not erase bad blocks ! */
                if (nand_block_checkbad(mtd, ((loff_t) page) << this->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 <= this->pagebuf && this->pagebuf < (page + pages_per_block))
                        this->pagebuf = -1;

                this->erase_cmd (mtd, page & this->pagemask);
                
                status = this->waitfunc (mtd, this, FL_ERASING);

                /* See if operation failed and additional status checks are available */
                if ((status & NAND_STATUS_FAIL) && (this->errstat)) {
                        status = this->errstat(mtd, this, 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 << this->page_shift);
                        goto erase_exit;
                }

                /* if BBT requires refresh, set the BBT rewrite flag to the page being erased */
                if (this->options & BBT_AUTO_REFRESH) {
                        if (((page & BBT_PAGE_MASK) == bbt_masked_page) && 
                             (page != this->bbt_td->pages[chipnr])) {
                                rewrite_bbt[chipnr] = (page << this->page_shift);
                        }
                }
                
                /* Increment page address and decrement length */
                len -= (1 << this->phys_erase_shift);
                page += pages_per_block;

                /* Check, if we cross a chip boundary */
                if (len && !(page & this->pagemask)) {
                        chipnr++;
                        this->select_chip(mtd, -1);
                        this->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 ((this->options & BBT_AUTO_REFRESH) && (this->bbt_td->options & NAND_BBT_PERCHIP)) {
                                bbt_masked_page = this->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 ((this->options & BBT_AUTO_REFRESH) && (!ret)) {
                for (chipnr = 0; chipnr < this->numchips; chipnr++) {
                        if (rewrite_bbt[chipnr]) {
                                /* 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], this->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 *this = mtd->priv;

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

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


/**
 * nand_block_isbad - [MTD Interface] Check whether the block at the given offset is bad
 * @mtd:        MTD device structure
 * @ofs:        offset relative to mtd start
 */
static int nand_block_isbad (struct mtd_info *mtd, loff_t ofs)
{
        /* Check for invalid offset */
        if (ofs > mtd->size) 
                return -EINVAL;
        
        return nand_block_checkbad (mtd, ofs, 1, 0);
}

/**
 * nand_block_markbad - [MTD Interface] Mark the 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 *this = 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 this->block_markbad(mtd, ofs);
}

/**
 * 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 not initialized 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
 *
 */
int nand_scan (struct mtd_info *mtd, int maxchips)
{
        int i, nand_maf_id, nand_dev_id, busw, maf_id;
        struct nand_chip *this = mtd->priv;

        /* Get buswidth to select the correct functions*/
        busw = this->options & NAND_BUSWIDTH_16;

        /* check for proper chip_delay setup, set 20us if not */
        if (!this->chip_delay)
                this->chip_delay = 20;

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

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

        if (!this->select_chip)
                this->select_chip = nand_select_chip;
        if (!this->write_byte)
                this->write_byte = busw ? nand_write_byte16 : nand_write_byte;
        if (!this->read_byte)
                this->read_byte = busw ? nand_read_byte16 : nand_read_byte;
        if (!this->write_word)
                this->write_word = nand_write_word;
        if (!this->read_word)
                this->read_word = nand_read_word;
        if (!this->block_bad)
                this->block_bad = nand_block_bad;
        if (!this->block_markbad)
                this->block_markbad = nand_default_block_markbad;
        if (!this->write_buf)
                this->write_buf = busw ? nand_write_buf16 : nand_write_buf;
        if (!this->read_buf)
                this->read_buf = busw ? nand_read_buf16 : nand_read_buf;
        if (!this->verify_buf)
                this->verify_buf = busw ? nand_verify_buf16 : nand_verify_buf;
        if (!this->scan_bbt)
                this->scan_bbt = nand_default_bbt;

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

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

        /* Read manufacturer and device IDs */
        nand_maf_id = this->read_byte(mtd);
        nand_dev_id = this->read_byte(mtd);

        /* Print and store flash device information */
        for (i = 0; nand_flash_ids[i].name != NULL; i++) {
                                
                if (nand_dev_id != nand_flash_ids[i].id) 
                        continue;

                if (!mtd->name) mtd->name = nand_flash_ids[i].name;
                this->chipsize = nand_flash_ids[i].chipsize << 20;
                
                /* New 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 = this->read_byte(mtd);
                        /* The 4th id byte is the important one */
                        extid = this->read_byte(mtd);
                        /* Calc pagesize */
                        mtd->oobblock = 1024 << (extid & 0x3);
                        extid >>= 2;
                        /* Calc oobsize */
                        mtd->oobsize = (8 << (extid & 0x03)) * (mtd->oobblock / 512);
                        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 this data hardcoded in the
                         * device id table */
                        mtd->erasesize = nand_flash_ids[i].erasesize;
                        mtd->oobblock = nand_flash_ids[i].pagesize;
                        mtd->oobsize = mtd->oobblock / 32;
                        busw = nand_flash_ids[i].options & NAND_BUSWIDTH_16;
                }

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

                /* Check, if buswidth is correct. Hardware drivers should set
                 * this correct ! */
                if (busw != (this->options & NAND_BUSWIDTH_16)) {
                        printk (KERN_INFO "NAND device: Manufacturer ID:"
                                " 0x%02x, Chip ID: 0x%02x (%s %s)\n", nand_maf_id, nand_dev_id, 
                                nand_manuf_ids[maf_id].name , mtd->name);
                        printk (KERN_WARNING 
                                "NAND bus width %d instead %d bit\n", 
                                        (this->options & NAND_BUSWIDTH_16) ? 16 : 8,
                                        busw ? 16 : 8);
                        this->select_chip(mtd, -1);
                        return 1;       
                }
                
                /* Calculate the address shift from the page size */    
                this->page_shift = ffs(mtd->oobblock) - 1;
                this->bbt_erase_shift = this->phys_erase_shift = ffs(mtd->erasesize) - 1;
                this->chip_shift = ffs(this->chipsize) - 1;

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

                /* Get chip options, preserve non chip based options */
                this->options &= ~NAND_CHIPOPTIONS_MSK;
                this->options |= nand_flash_ids[i].options & NAND_CHIPOPTIONS_MSK;
                /* Set this as a default. Board drivers can override it, if neccecary */
                this->options |= NAND_NO_AUTOINCR;
                /* Check if this is a not a samsung device. Do not clear the options
                 * for chips which are not having an extended id.
                 */     
                if (nand_maf_id != NAND_MFR_SAMSUNG && !nand_flash_ids[i].pagesize)
                        this->options &= ~NAND_SAMSUNG_LP_OPTIONS;
                
                /* Check for AND chips with 4 page planes */
                if (this->options & NAND_4PAGE_ARRAY)
                        this->erase_cmd = multi_erase_cmd;
                else
                        this->erase_cmd = single_erase_cmd;

                /* Do not replace user supplied command function ! */
                if (mtd->oobblock > 512 && this->cmdfunc == nand_command)
                        this->cmdfunc = nand_command_lp;
                                
                printk (KERN_INFO "NAND device: Manufacturer ID:"
                        " 0x%02x, Chip ID: 0x%02x (%s %s)\n", nand_maf_id, nand_dev_id, 
                        nand_manuf_ids[maf_id].name , nand_flash_ids[i].name);
                break;
        }

        if (!nand_flash_ids[i].name) {
                printk (KERN_WARNING "No NAND device found!!!\n");
                this->select_chip(mtd, -1);
                return 1;
        }

        for (i=1; i < maxchips; i++) {
                this->select_chip(mtd, i);

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

                /* Read manufacturer and device IDs */
                if (nand_maf_id != this->read_byte(mtd) ||
                    nand_dev_id != this->read_byte(mtd))
                        break;
        }
        if (i > 1)
                printk(KERN_INFO "%d NAND chips detected\n", i);
        
        /* Allocate buffers, if neccecary */
        if (!this->oob_buf) {
                size_t len;
                len = mtd->oobsize << (this->phys_erase_shift - this->page_shift);
                this->oob_buf = kmalloc (len, GFP_KERNEL);
                if (!this->oob_buf) {
                        printk (KERN_ERR "nand_scan(): Cannot allocate oob_buf\n");
                        return -ENOMEM;
                }
                this->options |= NAND_OOBBUF_ALLOC;
        }
        
        if (!this->data_buf) {
                size_t len;
                len = mtd->oobblock + mtd->oobsize;
                this->data_buf = kmalloc (len, GFP_KERNEL);
                if (!this->data_buf) {
                        if (this->options & NAND_OOBBUF_ALLOC)
                                kfree (this->oob_buf);
                        printk (KERN_ERR "nand_scan(): Cannot allocate data_buf\n");
                        return -ENOMEM;
                }
                this->options |= NAND_DATABUF_ALLOC;
        }

        /* Store the number of chips and calc total size for mtd */
        this->numchips = i;
        mtd->size = i * this->chipsize;
        /* Convert chipsize to number of pages per chip -1. */
        this->pagemask = (this->chipsize >> this->page_shift) - 1;
        /* Preset the internal oob buffer */
        memset(this->oob_buf, 0xff, mtd->oobsize << (this->phys_erase_shift - this->page_shift));

        /* If no default placement scheme is given, select an
         * appropriate one */
        if (!this->autooob) {
                /* Select the appropriate default oob placement scheme for
                 * placement agnostic filesystems */
                switch (mtd->oobsize) { 
                case 8:
                        this->autooob = &nand_oob_8;
                        break;
                case 16:
                        this->autooob = &nand_oob_16;
                        break;
                case 64:
                        this->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; this->autooob->oobfree[i][1]; i++)
                mtd->oobavail += this->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 
        */
        this->eccsize = 256;    /* set default eccsize */       
        this->eccbytes = 3;

        switch (this->eccmode) {
        case NAND_ECC_HW12_2048:
                if (mtd->oobblock < 2048) {
                        printk(KERN_WARNING "2048 byte HW ECC not possible on %d byte page size, fallback to SW ECC\n",
                               mtd->oobblock);
                        this->eccmode = NAND_ECC_SOFT;
                        this->calculate_ecc = nand_calculate_ecc;
                        this->correct_data = nand_correct_data;
                } else
                        this->eccsize = 2048;
                break;

        case NAND_ECC_HW3_512: 
        case NAND_ECC_HW6_512: 
        case NAND_ECC_HW8_512: 
                if (mtd->oobblock == 256) {
                        printk (KERN_WARNING "512 byte HW ECC not possible on 256 Byte pagesize, fallback to SW ECC \n");
                        this->eccmode = NAND_ECC_SOFT;
                        this->calculate_ecc = nand_calculate_ecc;
                        this->correct_data = nand_correct_data;
                } else 
                        this->eccsize = 512; /* set eccsize to 512 */
                break;
                        
        case NAND_ECC_HW3_256:
                break;
                
        case NAND_ECC_NONE: 
                printk (KERN_WARNING "NAND_ECC_NONE selected by board driver. This is not recommended !!\n");
                this->eccmode = NAND_ECC_NONE;
                break;

        case NAND_ECC_SOFT:     
                this->calculate_ecc = nand_calculate_ecc;
                this->correct_data = nand_correct_data;
                break;

        default:
                printk (KERN_WARNING "Invalid NAND_ECC_MODE %d\n", this->eccmode);
                BUG();  
        }       

        /* Check hardware ecc function availability and adjust number of ecc bytes per 
         * calculation step
        */
        switch (this->eccmode) {
        case NAND_ECC_HW12_2048:
                this->eccbytes += 4;
        case NAND_ECC_HW8_512: 
                this->eccbytes += 2;
        case NAND_ECC_HW6_512: 
                this->eccbytes += 3;
        case NAND_ECC_HW3_512: 
        case NAND_ECC_HW3_256:
                if (this->calculate_ecc && this->correct_data && this->enable_hwecc)
                        break;
                printk (KERN_WARNING "No ECC functions supplied, Hardware ECC not possible\n");
                BUG();  
        }
                
        mtd->eccsize = this->eccsize;
        
        /* Set the number of read / write steps for one page to ensure ECC generation */
        switch (this->eccmode) {
        case NAND_ECC_HW12_2048:
                this->eccsteps = mtd->oobblock / 2048;
                break;
        case NAND_ECC_HW3_512:
        case NAND_ECC_HW6_512:
        case NAND_ECC_HW8_512:
                this->eccsteps = mtd->oobblock / 512;
                break;
        case NAND_ECC_HW3_256:
        case NAND_ECC_SOFT:     
                this->eccsteps = mtd->oobblock / 256;
                break;
                
        case NAND_ECC_NONE: 
                this->eccsteps = 1;
                break;
        }
        
        /* Initialize state, waitqueue and spinlock */
        this->state = FL_READY;
        init_waitqueue_head (&this->wq);
        spin_lock_init (&this->chip_lock);

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

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

        /* Fill in remaining MTD driver data */
        mtd->type = MTD_NANDFLASH;
        mtd->flags = MTD_CAP_NANDFLASH | MTD_ECC;
        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_ecc = nand_read_ecc;
        mtd->write_ecc = nand_write_ecc;
        mtd->read_oob = nand_read_oob;
        mtd->write_oob = nand_write_oob;
        mtd->readv = NULL;
        mtd->writev = nand_writev;
        mtd->writev_ecc = nand_writev_ecc;
        mtd->sync = nand_sync;
        mtd->lock = NULL;
        mtd->unlock = NULL;
        mtd->suspend = NULL;
        mtd->resume = NULL;
        mtd->block_isbad = nand_block_isbad;
        mtd->block_markbad = nand_block_markbad;

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

        mtd->owner = THIS_MODULE;
        
        /* Check, if we should skip the bad block table scan */
        if (this->options & NAND_SKIP_BBTSCAN)
                return 0;

        /* Build bad block table */
        return this->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 *this = 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, if allocated */
        if (this->bbt)
                kfree (this->bbt);
        /* Buffer allocated by nand_scan ? */
        if (this->options & NAND_OOBBUF_ALLOC)
                kfree (this->oob_buf);
        /* Buffer allocated by nand_scan ? */
        if (this->options & NAND_DATABUF_ALLOC)
                kfree (this->data_buf);
}

EXPORT_SYMBOL (nand_scan);
EXPORT_SYMBOL (nand_release);

MODULE_LICENSE ("GPL");
MODULE_AUTHOR ("Steven J. Hill <sjhill@realitydiluted.com>, Thomas Gleixner <tglx@linutronix.de>");
MODULE_DESCRIPTION ("Generic NAND flash driver code");