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nand_bbt.c

/*
 *  drivers/mtd/nand_bbt.c
 *
 *  Overview:
 *   Bad block table support for the NAND driver
 *
 *  Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
 *
 * $Id: nand_bbt.c,v 1.36 2005/11/07 11:14:30 gleixner Exp $
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Description:
 *
 * When nand_scan_bbt is called, then it tries to find the bad block table
 * depending on the options in the bbt descriptor(s). If a bbt is found
 * then the contents are read and the memory based bbt is created. If a
 * mirrored bbt is selected then the mirror is searched too and the
 * versions are compared. If the mirror has a greater version number
 * than the mirror bbt is used to build the memory based bbt.
 * If the tables are not versioned, then we "or" the bad block information.
 * If one of the bbt's is out of date or does not exist it is (re)created.
 * If no bbt exists at all then the device is scanned for factory marked
 * good / bad blocks and the bad block tables are created.
 *
 * For manufacturer created bbts like the one found on M-SYS DOC devices
 * the bbt is searched and read but never created
 *
 * The autogenerated bad block table is located in the last good blocks
 * of the device. The table is mirrored, so it can be updated eventually.
 * The table is marked in the oob area with an ident pattern and a version
 * number which indicates which of both tables is more up to date.
 *
 * The table uses 2 bits per block
 * 11b:     block is good
 * 00b:     block is factory marked bad
 * 01b, 10b:      block is marked bad due to wear
 *
 * The memory bad block table uses the following scheme:
 * 00b:           block is good
 * 01b:           block is marked bad due to wear
 * 10b:           block is reserved (to protect the bbt area)
 * 11b:           block is factory marked bad
 *
 * Multichip devices like DOC store the bad block info per floor.
 *
 * Following assumptions are made:
 * - bbts start at a page boundary, if autolocated on a block boundary
 * - the space necessary for a bbt in FLASH does not exceed a block boundary
 *
 */

#include <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/bitops.h>
#include <linux/delay.h>
#include <linux/vmalloc.h>

/**
 * check_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf:    the buffer to search
 * @len:    the length of buffer to search
 * @paglen: the pagelength
 * @td:           search pattern descriptor
 *
 * Check for a pattern at the given place. Used to search bad block
 * tables and good / bad block identifiers.
 * If the SCAN_EMPTY option is set then check, if all bytes except the
 * pattern area contain 0xff
 *
*/
static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
{
      int i, end = 0;
      uint8_t *p = buf;

      end = paglen + td->offs;
      if (td->options & NAND_BBT_SCANEMPTY) {
            for (i = 0; i < end; i++) {
                  if (p[i] != 0xff)
                        return -1;
            }
      }
      p += end;

      /* Compare the pattern */
      for (i = 0; i < td->len; i++) {
            if (p[i] != td->pattern[i])
                  return -1;
      }

      if (td->options & NAND_BBT_SCANEMPTY) {
            p += td->len;
            end += td->len;
            for (i = end; i < len; i++) {
                  if (*p++ != 0xff)
                        return -1;
            }
      }
      return 0;
}

/**
 * check_short_pattern - [GENERIC] check if a pattern is in the buffer
 * @buf:    the buffer to search
 * @td:           search pattern descriptor
 *
 * Check for a pattern at the given place. Used to search bad block
 * tables and good / bad block identifiers. Same as check_pattern, but
 * no optional empty check
 *
*/
static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
{
      int i;
      uint8_t *p = buf;

      /* Compare the pattern */
      for (i = 0; i < td->len; i++) {
            if (p[td->offs + i] != td->pattern[i])
                  return -1;
      }
      return 0;
}

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

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

      while (totlen) {
            len = min(totlen, (size_t) (1 << this->bbt_erase_shift));
            res = mtd->read(mtd, from, len, &retlen, buf);
            if (res < 0) {
                  if (retlen != len) {
                        printk(KERN_INFO "nand_bbt: Error reading bad block table\n");
                        return res;
                  }
                  printk(KERN_WARNING "nand_bbt: ECC error while reading bad block table\n");
            }

            /* Analyse data */
            for (i = 0; i < len; i++) {
                  uint8_t dat = buf[i];
                  for (j = 0; j < 8; j += bits, act += 2) {
                        uint8_t tmp = (dat >> j) & msk;
                        if (tmp == msk)
                              continue;
                        if (reserved_block_code && (tmp == reserved_block_code)) {
                              printk(KERN_DEBUG "nand_read_bbt: Reserved block at 0x%08x\n",
                                     ((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
                              this->bbt[offs + (act >> 3)] |= 0x2 << (act & 0x06);
                              mtd->ecc_stats.bbtblocks++;
                              continue;
                        }
                        /* Leave it for now, if its matured we can move this
                         * message to MTD_DEBUG_LEVEL0 */
                        printk(KERN_DEBUG "nand_read_bbt: Bad block at 0x%08x\n",
                               ((offs << 2) + (act >> 1)) << this->bbt_erase_shift);
                        /* Factory marked bad or worn out ? */
                        if (tmp == 0)
                              this->bbt[offs + (act >> 3)] |= 0x3 << (act & 0x06);
                        else
                              this->bbt[offs + (act >> 3)] |= 0x1 << (act & 0x06);
                        mtd->ecc_stats.badblocks++;
                  }
            }
            totlen -= len;
            from += len;
      }
      return 0;
}

/**
 * read_abs_bbt - [GENERIC] Read the bad block table starting at a given page
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @td:           descriptor for the bad block table
 * @chip:   read the table for a specific chip, -1 read all chips.
 *          Applies only if NAND_BBT_PERCHIP option is set
 *
 * Read the bad block table for all chips starting at a given page
 * We assume that the bbt bits are in consecutive order.
*/
static int read_abs_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td, int chip)
{
      struct nand_chip *this = mtd->priv;
      int res = 0, i;
      int bits;

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

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

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

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

/*
 * Scan write data with oob to flash
 */
static int scan_write_bbt(struct mtd_info *mtd, loff_t offs, size_t len,
                    uint8_t *buf, uint8_t *oob)
{
      struct mtd_oob_ops ops;

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

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

/**
 * read_abs_bbts - [GENERIC] Read the bad block table(s) for all chips starting at a given page
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @td:           descriptor for the bad block table
 * @md:           descriptor for the bad block table mirror
 *
 * Read the bad block table(s) for all chips starting at a given page
 * We assume that the bbt bits are in consecutive order.
 *
*/
static int read_abs_bbts(struct mtd_info *mtd, uint8_t *buf,
                   struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
      struct nand_chip *this = mtd->priv;

      /* Read the primary version, if available */
      if (td->options & NAND_BBT_VERSION) {
            scan_read_raw(mtd, buf, td->pages[0] << this->page_shift,
                        mtd->writesize);
            td->version[0] = buf[mtd->writesize + td->veroffs];
            printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
                   td->pages[0], td->version[0]);
      }

      /* Read the mirror version, if available */
      if (md && (md->options & NAND_BBT_VERSION)) {
            scan_read_raw(mtd, buf, md->pages[0] << this->page_shift,
                        mtd->writesize);
            md->version[0] = buf[mtd->writesize + md->veroffs];
            printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
                   md->pages[0], md->version[0]);
      }
      return 1;
}

/*
 * Scan a given block full
 */
static int scan_block_full(struct mtd_info *mtd, struct nand_bbt_descr *bd,
                     loff_t offs, uint8_t *buf, size_t readlen,
                     int scanlen, int len)
{
      int ret, j;

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

      for (j = 0; j < len; j++, buf += scanlen) {
            if (check_pattern(buf, scanlen, mtd->writesize, bd))
                  return 1;
      }
      return 0;
}

/*
 * Scan a given block partially
 */
static int scan_block_fast(struct mtd_info *mtd, struct nand_bbt_descr *bd,
                     loff_t offs, uint8_t *buf, int len)
{
      struct mtd_oob_ops ops;
      int j, ret;

      ops.ooblen = mtd->oobsize;
      ops.oobbuf = buf;
      ops.ooboffs = 0;
      ops.datbuf = NULL;
      ops.mode = MTD_OOB_PLACE;

      for (j = 0; j < len; j++) {
            /*
             * Read the full oob until read_oob is fixed to
             * handle single byte reads for 16 bit
             * buswidth
             */
            ret = mtd->read_oob(mtd, offs, &ops);
            if (ret)
                  return ret;

            if (check_short_pattern(buf, bd))
                  return 1;

            offs += mtd->writesize;
      }
      return 0;
}

/**
 * create_bbt - [GENERIC] Create a bad block table by scanning the device
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @bd:           descriptor for the good/bad block search pattern
 * @chip:   create the table for a specific chip, -1 read all chips.
 *          Applies only if NAND_BBT_PERCHIP option is set
 *
 * Create a bad block table by scanning the device
 * for the given good/bad block identify pattern
 */
static int create_bbt(struct mtd_info *mtd, uint8_t *buf,
      struct nand_bbt_descr *bd, int chip)
{
      struct nand_chip *this = mtd->priv;
      int i, numblocks, len, scanlen;
      int startblock;
      loff_t from;
      size_t readlen;

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

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

      if (!(bd->options & NAND_BBT_SCANEMPTY)) {
            /* We need only read few bytes from the OOB area */
            scanlen = 0;
            readlen = bd->len;
      } else {
            /* Full page content should be read */
            scanlen = mtd->writesize + mtd->oobsize;
            readlen = len * mtd->writesize;
      }

      if (chip == -1) {
            /* Note that numblocks is 2 * (real numblocks) here, see i+=2
             * below as it makes shifting and masking less painful */
            numblocks = mtd->size >> (this->bbt_erase_shift - 1);
            startblock = 0;
            from = 0;
      } else {
            if (chip >= this->numchips) {
                  printk(KERN_WARNING "create_bbt(): chipnr (%d) > available chips (%d)\n",
                         chip + 1, this->numchips);
                  return -EINVAL;
            }
            numblocks = this->chipsize >> (this->bbt_erase_shift - 1);
            startblock = chip * numblocks;
            numblocks += startblock;
            from = startblock << (this->bbt_erase_shift - 1);
      }

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

            if (bd->options & NAND_BBT_SCANALLPAGES)
                  ret = scan_block_full(mtd, bd, from, buf, readlen,
                                    scanlen, len);
            else
                  ret = scan_block_fast(mtd, bd, from, buf, len);

            if (ret < 0)
                  return ret;

            if (ret) {
                  this->bbt[i >> 3] |= 0x03 << (i & 0x6);
                  printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
                         i >> 1, (unsigned int)from);
                  mtd->ecc_stats.badblocks++;
            }

            i += 2;
            from += (1 << this->bbt_erase_shift);
      }
      return 0;
}

/**
 * search_bbt - [GENERIC] scan the device for a specific bad block table
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @td:           descriptor for the bad block table
 *
 * Read the bad block table by searching for a given ident pattern.
 * Search is preformed either from the beginning up or from the end of
 * the device downwards. The search starts always at the start of a
 * block.
 * If the option NAND_BBT_PERCHIP is given, each chip is searched
 * for a bbt, which contains the bad block information of this chip.
 * This is necessary to provide support for certain DOC devices.
 *
 * The bbt ident pattern resides in the oob area of the first page
 * in a block.
 */
static int search_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td)
{
      struct nand_chip *this = mtd->priv;
      int i, chips;
      int bits, startblock, block, dir;
      int scanlen = mtd->writesize + mtd->oobsize;
      int bbtblocks;
      int blocktopage = this->bbt_erase_shift - this->page_shift;

      /* Search direction top -> down ? */
      if (td->options & NAND_BBT_LASTBLOCK) {
            startblock = (mtd->size >> this->bbt_erase_shift) - 1;
            dir = -1;
      } else {
            startblock = 0;
            dir = 1;
      }

      /* Do we have a bbt per chip ? */
      if (td->options & NAND_BBT_PERCHIP) {
            chips = this->numchips;
            bbtblocks = this->chipsize >> this->bbt_erase_shift;
            startblock &= bbtblocks - 1;
      } else {
            chips = 1;
            bbtblocks = mtd->size >> this->bbt_erase_shift;
      }

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

      for (i = 0; i < chips; i++) {
            /* Reset version information */
            td->version[i] = 0;
            td->pages[i] = -1;
            /* Scan the maximum number of blocks */
            for (block = 0; block < td->maxblocks; block++) {

                  int actblock = startblock + dir * block;
                  loff_t offs = actblock << this->bbt_erase_shift;

                  /* Read first page */
                  scan_read_raw(mtd, buf, offs, mtd->writesize);
                  if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
                        td->pages[i] = actblock << blocktopage;
                        if (td->options & NAND_BBT_VERSION) {
                              td->version[i] = buf[mtd->writesize + td->veroffs];
                        }
                        break;
                  }
            }
            startblock += this->chipsize >> this->bbt_erase_shift;
      }
      /* Check, if we found a bbt for each requested chip */
      for (i = 0; i < chips; i++) {
            if (td->pages[i] == -1)
                  printk(KERN_WARNING "Bad block table not found for chip %d\n", i);
            else
                  printk(KERN_DEBUG "Bad block table found at page %d, version 0x%02X\n", td->pages[i],
                         td->version[i]);
      }
      return 0;
}

/**
 * search_read_bbts - [GENERIC] scan the device for bad block table(s)
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @td:           descriptor for the bad block table
 * @md:           descriptor for the bad block table mirror
 *
 * Search and read the bad block table(s)
*/
static int search_read_bbts(struct mtd_info *mtd, uint8_t * buf, struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
      /* Search the primary table */
      search_bbt(mtd, buf, td);

      /* Search the mirror table */
      if (md)
            search_bbt(mtd, buf, md);

      /* Force result check */
      return 1;
}

/**
 * write_bbt - [GENERIC] (Re)write the bad block table
 *
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @td:           descriptor for the bad block table
 * @md:           descriptor for the bad block table mirror
 * @chipsel:      selector for a specific chip, -1 for all
 *
 * (Re)write the bad block table
 *
*/
static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
                 struct nand_bbt_descr *td, struct nand_bbt_descr *md,
                 int chipsel)
{
      struct nand_chip *this = mtd->priv;
      struct erase_info einfo;
      int i, j, res, chip = 0;
      int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
      int nrchips, bbtoffs, pageoffs, ooboffs;
      uint8_t msk[4];
      uint8_t rcode = td->reserved_block_code;
      size_t retlen, len = 0;
      loff_t to;
      struct mtd_oob_ops ops;

      ops.ooblen = mtd->oobsize;
      ops.ooboffs = 0;
      ops.datbuf = NULL;
      ops.mode = MTD_OOB_PLACE;

      if (!rcode)
            rcode = 0xff;
      /* Write bad block table per chip rather than per device ? */
      if (td->options & NAND_BBT_PERCHIP) {
            numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
            /* Full device write or specific chip ? */
            if (chipsel == -1) {
                  nrchips = this->numchips;
            } else {
                  nrchips = chipsel + 1;
                  chip = chipsel;
            }
      } else {
            numblocks = (int)(mtd->size >> this->bbt_erase_shift);
            nrchips = 1;
      }

      /* Loop through the chips */
      for (; chip < nrchips; chip++) {

            /* There was already a version of the table, reuse the page
             * This applies for absolute placement too, as we have the
             * page nr. in td->pages.
             */
            if (td->pages[chip] != -1) {
                  page = td->pages[chip];
                  goto write;
            }

            /* Automatic placement of the bad block table */
            /* Search direction top -> down ? */
            if (td->options & NAND_BBT_LASTBLOCK) {
                  startblock = numblocks * (chip + 1) - 1;
                  dir = -1;
            } else {
                  startblock = chip * numblocks;
                  dir = 1;
            }

            for (i = 0; i < td->maxblocks; i++) {
                  int block = startblock + dir * i;
                  /* Check, if the block is bad */
                  switch ((this->bbt[block >> 2] >>
                         (2 * (block & 0x03))) & 0x03) {
                  case 0x01:
                  case 0x03:
                        continue;
                  }
                  page = block <<
                        (this->bbt_erase_shift - this->page_shift);
                  /* Check, if the block is used by the mirror table */
                  if (!md || md->pages[chip] != page)
                        goto write;
            }
            printk(KERN_ERR "No space left to write bad block table\n");
            return -ENOSPC;
      write:

            /* Set up shift count and masks for the flash table */
            bits = td->options & NAND_BBT_NRBITS_MSK;
            msk[2] = ~rcode;
            switch (bits) {
            case 1: sft = 3; sftmsk = 0x07; msk[0] = 0x00; msk[1] = 0x01;
                  msk[3] = 0x01;
                  break;
            case 2: sft = 2; sftmsk = 0x06; msk[0] = 0x00; msk[1] = 0x01;
                  msk[3] = 0x03;
                  break;
            case 4: sft = 1; sftmsk = 0x04; msk[0] = 0x00; msk[1] = 0x0C;
                  msk[3] = 0x0f;
                  break;
            case 8: sft = 0; sftmsk = 0x00; msk[0] = 0x00; msk[1] = 0x0F;
                  msk[3] = 0xff;
                  break;
            default: return -EINVAL;
            }

            bbtoffs = chip * (numblocks >> 2);

            to = ((loff_t) page) << this->page_shift;

            /* Must we save the block contents ? */
            if (td->options & NAND_BBT_SAVECONTENT) {
                  /* Make it block aligned */
                  to &= ~((loff_t) ((1 << this->bbt_erase_shift) - 1));
                  len = 1 << this->bbt_erase_shift;
                  res = mtd->read(mtd, to, len, &retlen, buf);
                  if (res < 0) {
                        if (retlen != len) {
                              printk(KERN_INFO "nand_bbt: Error "
                                     "reading block for writing "
                                     "the bad block table\n");
                              return res;
                        }
                        printk(KERN_WARNING "nand_bbt: ECC error "
                               "while reading block for writing "
                               "bad block table\n");
                  }
                  /* Read oob data */
                  ops.ooblen = (len >> this->page_shift) * mtd->oobsize;
                  ops.oobbuf = &buf[len];
                  res = mtd->read_oob(mtd, to + mtd->writesize, &ops);
                  if (res < 0 || ops.oobretlen != ops.ooblen)
                        goto outerr;

                  /* Calc the byte offset in the buffer */
                  pageoffs = page - (int)(to >> this->page_shift);
                  offs = pageoffs << this->page_shift;
                  /* Preset the bbt area with 0xff */
                  memset(&buf[offs], 0xff, (size_t) (numblocks >> sft));
                  ooboffs = len + (pageoffs * mtd->oobsize);

            } else {
                  /* Calc length */
                  len = (size_t) (numblocks >> sft);
                  /* Make it page aligned ! */
                  len = (len + (mtd->writesize - 1)) &
                        ~(mtd->writesize - 1);
                  /* Preset the buffer with 0xff */
                  memset(buf, 0xff, len +
                         (len >> this->page_shift)* mtd->oobsize);
                  offs = 0;
                  ooboffs = len;
                  /* Pattern is located in oob area of first page */
                  memcpy(&buf[ooboffs + td->offs], td->pattern, td->len);
            }

            if (td->options & NAND_BBT_VERSION)
                  buf[ooboffs + td->veroffs] = td->version[chip];

            /* walk through the memory table */
            for (i = 0; i < numblocks;) {
                  uint8_t dat;
                  dat = this->bbt[bbtoffs + (i >> 2)];
                  for (j = 0; j < 4; j++, i++) {
                        int sftcnt = (i << (3 - sft)) & sftmsk;
                        /* Do not store the reserved bbt blocks ! */
                        buf[offs + (i >> sft)] &=
                              ~(msk[dat & 0x03] << sftcnt);
                        dat >>= 2;
                  }
            }

            memset(&einfo, 0, sizeof(einfo));
            einfo.mtd = mtd;
            einfo.addr = (unsigned long)to;
            einfo.len = 1 << this->bbt_erase_shift;
            res = nand_erase_nand(mtd, &einfo, 1);
            if (res < 0)
                  goto outerr;

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

            printk(KERN_DEBUG "Bad block table written to 0x%08x, version "
                   "0x%02X\n", (unsigned int)to, td->version[chip]);

            /* Mark it as used */
            td->pages[chip] = page;
      }
      return 0;

 outerr:
      printk(KERN_WARNING
             "nand_bbt: Error while writing bad block table %d\n", res);
      return res;
}

/**
 * nand_memory_bbt - [GENERIC] create a memory based bad block table
 * @mtd:    MTD device structure
 * @bd:           descriptor for the good/bad block search pattern
 *
 * The function creates a memory based bbt by scanning the device
 * for manufacturer / software marked good / bad blocks
*/
static inline int nand_memory_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
      struct nand_chip *this = mtd->priv;

      bd->options &= ~NAND_BBT_SCANEMPTY;
      return create_bbt(mtd, this->buffers->databuf, bd, -1);
}

/**
 * check_create - [GENERIC] create and write bbt(s) if necessary
 * @mtd:    MTD device structure
 * @buf:    temporary buffer
 * @bd:           descriptor for the good/bad block search pattern
 *
 * The function checks the results of the previous call to read_bbt
 * and creates / updates the bbt(s) if necessary
 * Creation is necessary if no bbt was found for the chip/device
 * Update is necessary if one of the tables is missing or the
 * version nr. of one table is less than the other
*/
static int check_create(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd)
{
      int i, chips, writeops, chipsel, res;
      struct nand_chip *this = mtd->priv;
      struct nand_bbt_descr *td = this->bbt_td;
      struct nand_bbt_descr *md = this->bbt_md;
      struct nand_bbt_descr *rd, *rd2;

      /* Do we have a bbt per chip ? */
      if (td->options & NAND_BBT_PERCHIP)
            chips = this->numchips;
      else
            chips = 1;

      for (i = 0; i < chips; i++) {
            writeops = 0;
            rd = NULL;
            rd2 = NULL;
            /* Per chip or per device ? */
            chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
            /* Mirrored table avilable ? */
            if (md) {
                  if (td->pages[i] == -1 && md->pages[i] == -1) {
                        writeops = 0x03;
                        goto create;
                  }

                  if (td->pages[i] == -1) {
                        rd = md;
                        td->version[i] = md->version[i];
                        writeops = 1;
                        goto writecheck;
                  }

                  if (md->pages[i] == -1) {
                        rd = td;
                        md->version[i] = td->version[i];
                        writeops = 2;
                        goto writecheck;
                  }

                  if (td->version[i] == md->version[i]) {
                        rd = td;
                        if (!(td->options & NAND_BBT_VERSION))
                              rd2 = md;
                        goto writecheck;
                  }

                  if (((int8_t) (td->version[i] - md->version[i])) > 0) {
                        rd = td;
                        md->version[i] = td->version[i];
                        writeops = 2;
                  } else {
                        rd = md;
                        td->version[i] = md->version[i];
                        writeops = 1;
                  }

                  goto writecheck;

            } else {
                  if (td->pages[i] == -1) {
                        writeops = 0x01;
                        goto create;
                  }
                  rd = td;
                  goto writecheck;
            }
      create:
            /* Create the bad block table by scanning the device ? */
            if (!(td->options & NAND_BBT_CREATE))
                  continue;

            /* Create the table in memory by scanning the chip(s) */
            create_bbt(mtd, buf, bd, chipsel);

            td->version[i] = 1;
            if (md)
                  md->version[i] = 1;
      writecheck:
            /* read back first ? */
            if (rd)
                  read_abs_bbt(mtd, buf, rd, chipsel);
            /* If they weren't versioned, read both. */
            if (rd2)
                  read_abs_bbt(mtd, buf, rd2, chipsel);

            /* Write the bad block table to the device ? */
            if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
                  res = write_bbt(mtd, buf, td, md, chipsel);
                  if (res < 0)
                        return res;
            }

            /* Write the mirror bad block table to the device ? */
            if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
                  res = write_bbt(mtd, buf, md, td, chipsel);
                  if (res < 0)
                        return res;
            }
      }
      return 0;
}

/**
 * mark_bbt_regions - [GENERIC] mark the bad block table regions
 * @mtd:    MTD device structure
 * @td:           bad block table descriptor
 *
 * The bad block table regions are marked as "bad" to prevent
 * accidental erasures / writes. The regions are identified by
 * the mark 0x02.
*/
static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
{
      struct nand_chip *this = mtd->priv;
      int i, j, chips, block, nrblocks, update;
      uint8_t oldval, newval;

      /* Do we have a bbt per chip ? */
      if (td->options & NAND_BBT_PERCHIP) {
            chips = this->numchips;
            nrblocks = (int)(this->chipsize >> this->bbt_erase_shift);
      } else {
            chips = 1;
            nrblocks = (int)(mtd->size >> this->bbt_erase_shift);
      }

      for (i = 0; i < chips; i++) {
            if ((td->options & NAND_BBT_ABSPAGE) ||
                !(td->options & NAND_BBT_WRITE)) {
                  if (td->pages[i] == -1)
                        continue;
                  block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
                  block <<= 1;
                  oldval = this->bbt[(block >> 3)];
                  newval = oldval | (0x2 << (block & 0x06));
                  this->bbt[(block >> 3)] = newval;
                  if ((oldval != newval) && td->reserved_block_code)
                        nand_update_bbt(mtd, block << (this->bbt_erase_shift - 1));
                  continue;
            }
            update = 0;
            if (td->options & NAND_BBT_LASTBLOCK)
                  block = ((i + 1) * nrblocks) - td->maxblocks;
            else
                  block = i * nrblocks;
            block <<= 1;
            for (j = 0; j < td->maxblocks; j++) {
                  oldval = this->bbt[(block >> 3)];
                  newval = oldval | (0x2 << (block & 0x06));
                  this->bbt[(block >> 3)] = newval;
                  if (oldval != newval)
                        update = 1;
                  block += 2;
            }
            /* If we want reserved blocks to be recorded to flash, and some
               new ones have been marked, then we need to update the stored
               bbts.  This should only happen once. */
            if (update && td->reserved_block_code)
                  nand_update_bbt(mtd, (block - 2) << (this->bbt_erase_shift - 1));
      }
}

/**
 * nand_scan_bbt - [NAND Interface] scan, find, read and maybe create bad block table(s)
 * @mtd:    MTD device structure
 * @bd:           descriptor for the good/bad block search pattern
 *
 * The function checks, if a bad block table(s) is/are already
 * available. If not it scans the device for manufacturer
 * marked good / bad blocks and writes the bad block table(s) to
 * the selected place.
 *
 * The bad block table memory is allocated here. It must be freed
 * by calling the nand_free_bbt function.
 *
*/
int nand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
      struct nand_chip *this = mtd->priv;
      int len, res = 0;
      uint8_t *buf;
      struct nand_bbt_descr *td = this->bbt_td;
      struct nand_bbt_descr *md = this->bbt_md;

      len = mtd->size >> (this->bbt_erase_shift + 2);
      /* Allocate memory (2bit per block) and clear the memory bad block table */
      this->bbt = kzalloc(len, GFP_KERNEL);
      if (!this->bbt) {
            printk(KERN_ERR "nand_scan_bbt: Out of memory\n");
            return -ENOMEM;
      }

      /* If no primary table decriptor is given, scan the device
       * to build a memory based bad block table
       */
      if (!td) {
            if ((res = nand_memory_bbt(mtd, bd))) {
                  printk(KERN_ERR "nand_bbt: Can't scan flash and build the RAM-based BBT\n");
                  kfree(this->bbt);
                  this->bbt = NULL;
            }
            return res;
      }

      /* Allocate a temporary buffer for one eraseblock incl. oob */
      len = (1 << this->bbt_erase_shift);
      len += (len >> this->page_shift) * mtd->oobsize;
      buf = vmalloc(len);
      if (!buf) {
            printk(KERN_ERR "nand_bbt: Out of memory\n");
            kfree(this->bbt);
            this->bbt = NULL;
            return -ENOMEM;
      }

      /* Is the bbt at a given page ? */
      if (td->options & NAND_BBT_ABSPAGE) {
            res = read_abs_bbts(mtd, buf, td, md);
      } else {
            /* Search the bad block table using a pattern in oob */
            res = search_read_bbts(mtd, buf, td, md);
      }

      if (res)
            res = check_create(mtd, buf, bd);

      /* Prevent the bbt regions from erasing / writing */
      mark_bbt_region(mtd, td);
      if (md)
            mark_bbt_region(mtd, md);

      vfree(buf);
      return res;
}

/**
 * nand_update_bbt - [NAND Interface] update bad block table(s)
 * @mtd:    MTD device structure
 * @offs:   the offset of the newly marked block
 *
 * The function updates the bad block table(s)
*/
int nand_update_bbt(struct mtd_info *mtd, loff_t offs)
{
      struct nand_chip *this = mtd->priv;
      int len, res = 0, writeops = 0;
      int chip, chipsel;
      uint8_t *buf;
      struct nand_bbt_descr *td = this->bbt_td;
      struct nand_bbt_descr *md = this->bbt_md;

      if (!this->bbt || !td)
            return -EINVAL;

      len = mtd->size >> (this->bbt_erase_shift + 2);
      /* Allocate a temporary buffer for one eraseblock incl. oob */
      len = (1 << this->bbt_erase_shift);
      len += (len >> this->page_shift) * mtd->oobsize;
      buf = kmalloc(len, GFP_KERNEL);
      if (!buf) {
            printk(KERN_ERR "nand_update_bbt: Out of memory\n");
            return -ENOMEM;
      }

      writeops = md != NULL ? 0x03 : 0x01;

      /* Do we have a bbt per chip ? */
      if (td->options & NAND_BBT_PERCHIP) {
            chip = (int)(offs >> this->chip_shift);
            chipsel = chip;
      } else {
            chip = 0;
            chipsel = -1;
      }

      td->version[chip]++;
      if (md)
            md->version[chip]++;

      /* Write the bad block table to the device ? */
      if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
            res = write_bbt(mtd, buf, td, md, chipsel);
            if (res < 0)
                  goto out;
      }
      /* Write the mirror bad block table to the device ? */
      if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
            res = write_bbt(mtd, buf, md, td, chipsel);
      }

 out:
      kfree(buf);
      return res;
}

/* Define some generic bad / good block scan pattern which are used
 * while scanning a device for factory marked good / bad blocks. */
static uint8_t scan_ff_pattern[] = { 0xff, 0xff };

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

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

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

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

static uint8_t scan_agand_pattern[] = { 0x1C, 0x71, 0xC7, 0x1C, 0x71, 0xC7 };

static struct nand_bbt_descr agand_flashbased = {
      .options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
      .offs = 0x20,
      .len = 6,
      .pattern = scan_agand_pattern
};

/* Generic flash bbt decriptors
*/
static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };

static struct nand_bbt_descr bbt_main_descr = {
      .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
            | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
      .offs =     8,
      .len = 4,
      .veroffs = 12,
      .maxblocks = 4,
      .pattern = bbt_pattern
};

static struct nand_bbt_descr bbt_mirror_descr = {
      .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
            | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
      .offs =     8,
      .len = 4,
      .veroffs = 12,
      .maxblocks = 4,
      .pattern = mirror_pattern
};

/**
 * nand_default_bbt - [NAND Interface] Select a default bad block table for the device
 * @mtd:    MTD device structure
 *
 * This function selects the default bad block table
 * support for the device and calls the nand_scan_bbt function
 *
*/
int nand_default_bbt(struct mtd_info *mtd)
{
      struct nand_chip *this = mtd->priv;

      /* Default for AG-AND. We must use a flash based
       * bad block table as the devices have factory marked
       * _good_ blocks. Erasing those blocks leads to loss
       * of the good / bad information, so we _must_ store
       * this information in a good / bad table during
       * startup
       */
      if (this->options & NAND_IS_AND) {
            /* Use the default pattern descriptors */
            if (!this->bbt_td) {
                  this->bbt_td = &bbt_main_descr;
                  this->bbt_md = &bbt_mirror_descr;
            }
            this->options |= NAND_USE_FLASH_BBT;
            return nand_scan_bbt(mtd, &agand_flashbased);
      }

      /* Is a flash based bad block table requested ? */
      if (this->options & NAND_USE_FLASH_BBT) {
            /* Use the default pattern descriptors */
            if (!this->bbt_td) {
                  this->bbt_td = &bbt_main_descr;
                  this->bbt_md = &bbt_mirror_descr;
            }
            if (!this->badblock_pattern) {
                  this->badblock_pattern = (mtd->writesize > 512) ? &largepage_flashbased : &smallpage_flashbased;
            }
      } else {
            this->bbt_td = NULL;
            this->bbt_md = NULL;
            if (!this->badblock_pattern) {
                  this->badblock_pattern = (mtd->writesize > 512) ?
                      &largepage_memorybased : &smallpage_memorybased;
            }
      }
      return nand_scan_bbt(mtd, this->badblock_pattern);
}

/**
 * nand_isbad_bbt - [NAND Interface] Check if a block is bad
 * @mtd:    MTD device structure
 * @offs:   offset in the device
 * @allowbbt:     allow access to bad block table region
 *
*/
int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
      struct nand_chip *this = mtd->priv;
      int block;
      uint8_t res;

      /* Get block number * 2 */
      block = (int)(offs >> (this->bbt_erase_shift - 1));
      res = (this->bbt[block >> 3] >> (block & 0x06)) & 0x03;

      DEBUG(MTD_DEBUG_LEVEL2, "nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
            (unsigned int)offs, block >> 1, res);

      switch ((int)res) {
      case 0x00:
            return 0;
      case 0x01:
            return 1;
      case 0x02:
            return allowbbt ? 0 : 1;
      }
      return 1;
}

EXPORT_SYMBOL(nand_scan_bbt);
EXPORT_SYMBOL(nand_default_bbt);

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