/*
 *  drivers/mtd/nand.c
 *
 *  Overview:
 *   This is the generic MTD driver for NAND flash devices. It should be
 *   capable of working with almost all NAND chips currently available.
 *   Basic support for AG-AND chips is provided.
 *
 *      Additional technical information is available on
 *      http://www.linux-mtd.infradead.org/doc/nand.html
 *
 *  Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
 *                2002-2006 Thomas Gleixner (tglx@linutronix.de)
 *
 *  Credits:
 *      David Woodhouse for adding multichip support
 *
 *      Aleph One Ltd. and Toby Churchill Ltd. for supporting the
 *      rework for 2K page size chips
 *
 *  TODO:
 *      Enable cached programming for 2k page size chips
 *      Check, if mtd->ecctype should be set to MTD_ECC_HW
 *      if we have HW ecc support.
 *      The AG-AND chips have nice features for speed improvement,
 *      which are not supported yet. Read / program 4 pages in one go.
 *      BBT table is not serialized, has to be fixed
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        default:
                BUG();
        }
}

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

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

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

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

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

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

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

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

}

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

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

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

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

        return 0;
}

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

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

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

                nand_get_device(chip, mtd, FL_READING);

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

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

        if (getchip)
                nand_release_device(mtd);

        return res;
}

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

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

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

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

        return ret;
}

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

/**
 * nand_block_checkbad - [GENERIC] Check if a block is marked bad
 * @mtd:        MTD device structure
 * @ofs:        offset from device start
 * @getchip:    0, if the chip is already selected
 * @allowbbt:   1, if its allowed to access the bbt area
 *
 * Check, if the block is bad. Either by reading the bad block table or
 * calling of the scan function.
 */
static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
                               int allowbbt)
{
        struct nand_chip *chip = mtd->priv;

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

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

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

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

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

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

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

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

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

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

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

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

        nand_wait_ready(mtd);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

        nand_wait_ready(mtd);
}

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

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

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

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

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

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

        led_trigger_event(nand_led_trigger, LED_FULL);

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

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

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

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

/**
 * nand_read_page_raw - [Intern] read raw page data without ecc
 * @mtd:        mtd info structure
 * @chip:       nand chip info structure
 * @buf:        buffer to store read data
 */
static int nand_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                              uint8_t *buf)
{
        chip->read_buf(mtd, buf, mtd->writesize);
        chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
        return 0;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                oob += eccbytes;

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

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

        return 0;
}

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

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

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

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

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

        stats = mtd->ecc_stats;

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

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

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

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

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

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

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

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

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

                        buf += bytes;

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

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

                readlen -= bytes;

                if (!readlen)
                        break;

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

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

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

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

        if (ret)
                return ret;

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

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

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

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

        nand_get_device(chip, mtd, FL_READING);

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

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

        *retlen = chip->ops.retlen;

        nand_release_device(mtd);

        return ret;
}

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

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

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

        return 1;
}

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

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

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

        return status & NAND_STATUS_FAIL ? -EIO : 0;
}

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

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

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

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

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

        return status & NAND_STATUS_FAIL ? -EIO : 0;
}

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

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

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

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

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

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

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

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

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

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

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

                /* Increment page address */
                realpage++;

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

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

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

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

        ops->retlen = 0;

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

        nand_get_device(chip, mtd, FL_READING);

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

        default:
                goto out;
        }

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

 out:
        nand_release_device(mtd);
        return ret;
}


/**
 * nand_write_page_raw - [Intern] raw page write function
 * @mtd:        mtd info structure
 * @chip:       nand chip info structure
 * @buf:        data buffer
 */
static void nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                                const uint8_t *buf)
{
        chip->write_buf(mtd, buf, mtd->writesize);
        chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        switch(ops->mode) {

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

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

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

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

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

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

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

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

        if (subpage && oob)
                return -EINVAL;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        nand_get_device(chip, mtd, FL_WRITING);

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

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

        *retlen = chip->ops.retlen;

        nand_release_device(mtd);

        return ret;
}

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

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

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

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

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

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

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

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

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

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

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

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

        if (status)
                return status;

        ops->oobretlen = ops->ooblen;

        return 0;
}

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

        ops->retlen = 0;

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

        nand_get_device(chip, mtd, FL_WRITING);

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

        default:
                goto out;
        }

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

 out:
        nand_release_device(mtd);
        return ret;
}

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

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

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

{
        return nand_erase_nand(mtd, instr, 0);
}

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

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

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

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

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

        instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;

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

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

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

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

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

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

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

        instr->state = MTD_ERASING;

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

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

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

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

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

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

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

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

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

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

 erase_exit:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        return nand_get_device(chip, mtd, FL_PM_SUSPENDED);
}

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

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

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

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

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

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

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

}

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

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

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

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

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

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

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

        /* Read manufacturer and device IDs */

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

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

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

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

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

        chip->chipsize = type->chipsize << 20;

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

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

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

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

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

        chip->bbt_erase_shift = chip->phys_erase_shift =
                ffs(mtd->erasesize) - 1;
        chip->chip_shift = ffs(chip->chipsize) - 1;

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

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

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

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

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

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

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

        return type;
}

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

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

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

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

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

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

        return 0;
}


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

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

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

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

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

        /*
         * check ECC mode, default to software if 3byte/512byte hardware ECC is
         * selected and we have 256 byte pagesize fallback to software ECC
         */
        if (!chip->ecc.read_page_raw)
                chip->ecc.read_page_raw = nand_read_page_raw;
        if (!chip->ecc.write_page_raw)
                chip->ecc.write_page_raw = nand_write_page_raw;

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

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

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

        case NAND_ECC_SOFT:
                chip->ecc.calculate = nand_calculate_ecc;
                chip->ecc.correct = nand_correct_data;
                chip->ecc.read_page = nand_read_page_swecc;
                chip->ecc.read_subpage = nand_read_subpage;
                chip->ecc.write_page = nand_write_page_swecc;
                chip->ecc.read_oob = nand_read_oob_std;
                chip->ecc.write_oob = nand_write_oob_std;
                chip->ecc.size = 256;
                chip->ecc.bytes = 3;
                break;

        case NAND_ECC_NONE:
                printk(KERN_WARNING "NAND_ECC_NONE selected by board driver. "
                       "This is not recommended !!\n");
                chip->ecc.read_page = nand_read_page_raw;
                chip->ecc.write_page = nand_write_page_raw;
                chip->ecc.read_oob = nand_read_oob_std;
                chip->ecc.write_oob = nand_write_oob_std;
                chip->ecc.size = mtd->writesize;
                chip->ecc.bytes = 0;
                break;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

module_init(nand_base_init);
module_exit(nand_base_exit);

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