Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / mtd / nand / nand_bbt.c
diff --git a/kernel/drivers/mtd/nand/nand_bbt.c b/kernel/drivers/mtd/nand/nand_bbt.c
new file mode 100644 (file)
index 0000000..9bb8453
--- /dev/null
@@ -0,0 +1,1375 @@
+/*
+ *  drivers/mtd/nand_bbt.c
+ *
+ *  Overview:
+ *   Bad block table support for the NAND driver
+ *
+ *  Copyright © 2004 Thomas Gleixner (tglx@linutronix.de)
+ *
+ * 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 no flash based BBT
+ * (NAND_BBT_USE_FLASH) is specified then the device is scanned for factory
+ * marked good / bad blocks. This information is used to create a memory BBT.
+ * Once a new bad block is discovered then the "factory" information is updated
+ * on the device.
+ * If a flash based BBT is specified then the function first tries to find the
+ * BBT on flash. 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, then 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+ * If one of the BBTs is out of date or does not exist it is (re)created.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 auto generated 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. If the NAND
+ * controller needs the complete OOB area for the ECC information then the
+ * option NAND_BBT_NO_OOB should be used (along with NAND_BBT_USE_FLASH, of
+ * course): it moves the ident pattern and the version byte into the data area
+ * and the OOB area will remain untouched.
+ *
+ * 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/bbm.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/nand_ecc.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/vmalloc.h>
+#include <linux/export.h>
+#include <linux/string.h>
+
+#define BBT_BLOCK_GOOD         0x00
+#define BBT_BLOCK_WORN         0x01
+#define BBT_BLOCK_RESERVED     0x02
+#define BBT_BLOCK_FACTORY_BAD  0x03
+
+#define BBT_ENTRY_MASK         0x03
+#define BBT_ENTRY_SHIFT                2
+
+static int nand_update_bbt(struct mtd_info *mtd, loff_t offs);
+
+static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
+{
+       uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
+       entry >>= (block & BBT_ENTRY_MASK) * 2;
+       return entry & BBT_ENTRY_MASK;
+}
+
+static inline void bbt_mark_entry(struct nand_chip *chip, int block,
+               uint8_t mark)
+{
+       uint8_t msk = (mark & BBT_ENTRY_MASK) << ((block & BBT_ENTRY_MASK) * 2);
+       chip->bbt[block >> BBT_ENTRY_SHIFT] |= msk;
+}
+
+static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
+{
+       if (memcmp(buf, td->pattern, td->len))
+               return -1;
+       return 0;
+}
+
+/**
+ * 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.
+ */
+static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
+{
+       if (td->options & NAND_BBT_NO_OOB)
+               return check_pattern_no_oob(buf, td);
+
+       /* Compare the pattern */
+       if (memcmp(buf + paglen + td->offs, td->pattern, td->len))
+               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)
+{
+       /* Compare the pattern */
+       if (memcmp(buf + td->offs, td->pattern, td->len))
+               return -1;
+       return 0;
+}
+
+/**
+ * add_marker_len - compute the length of the marker in data area
+ * @td: BBT descriptor used for computation
+ *
+ * The length will be 0 if the marker is located in OOB area.
+ */
+static u32 add_marker_len(struct nand_bbt_descr *td)
+{
+       u32 len;
+
+       if (!(td->options & NAND_BBT_NO_OOB))
+               return 0;
+
+       len = td->len;
+       if (td->options & NAND_BBT_VERSION)
+               len++;
+       return len;
+}
+
+/**
+ * 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
+ * @td: the bbt describtion table
+ * @offs: block number offset in the table
+ *
+ * Read the bad block table starting from page.
+ */
+static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
+               struct nand_bbt_descr *td, int offs)
+{
+       int res, ret = 0, i, j, act = 0;
+       struct nand_chip *this = mtd->priv;
+       size_t retlen, len, totlen;
+       loff_t from;
+       int bits = td->options & NAND_BBT_NRBITS_MSK;
+       uint8_t msk = (uint8_t)((1 << bits) - 1);
+       u32 marker_len;
+       int reserved_block_code = td->reserved_block_code;
+
+       totlen = (num * bits) >> 3;
+       marker_len = add_marker_len(td);
+       from = ((loff_t)page) << this->page_shift;
+
+       while (totlen) {
+               len = min(totlen, (size_t)(1 << this->bbt_erase_shift));
+               if (marker_len) {
+                       /*
+                        * In case the BBT marker is not in the OOB area it
+                        * will be just in the first page.
+                        */
+                       len -= marker_len;
+                       from += marker_len;
+                       marker_len = 0;
+               }
+               res = mtd_read(mtd, from, len, &retlen, buf);
+               if (res < 0) {
+                       if (mtd_is_eccerr(res)) {
+                               pr_info("nand_bbt: ECC error in BBT at 0x%012llx\n",
+                                       from & ~mtd->writesize);
+                               return res;
+                       } else if (mtd_is_bitflip(res)) {
+                               pr_info("nand_bbt: corrected error in BBT at 0x%012llx\n",
+                                       from & ~mtd->writesize);
+                               ret = res;
+                       } else {
+                               pr_info("nand_bbt: error reading BBT\n");
+                               return res;
+                       }
+               }
+
+               /* Analyse data */
+               for (i = 0; i < len; i++) {
+                       uint8_t dat = buf[i];
+                       for (j = 0; j < 8; j += bits, act++) {
+                               uint8_t tmp = (dat >> j) & msk;
+                               if (tmp == msk)
+                                       continue;
+                               if (reserved_block_code && (tmp == reserved_block_code)) {
+                                       pr_info("nand_read_bbt: reserved block at 0x%012llx\n",
+                                                (loff_t)(offs + act) <<
+                                                this->bbt_erase_shift);
+                                       bbt_mark_entry(this, offs + act,
+                                                       BBT_BLOCK_RESERVED);
+                                       mtd->ecc_stats.bbtblocks++;
+                                       continue;
+                               }
+                               /*
+                                * Leave it for now, if it's matured we can
+                                * move this message to pr_debug.
+                                */
+                               pr_info("nand_read_bbt: bad block at 0x%012llx\n",
+                                        (loff_t)(offs + act) <<
+                                        this->bbt_erase_shift);
+                               /* Factory marked bad or worn out? */
+                               if (tmp == 0)
+                                       bbt_mark_entry(this, offs + act,
+                                                       BBT_BLOCK_FACTORY_BAD);
+                               else
+                                       bbt_mark_entry(this, offs + act,
+                                                       BBT_BLOCK_WORN);
+                               mtd->ecc_stats.badblocks++;
+                       }
+               }
+               totlen -= len;
+               from += len;
+       }
+       return ret;
+}
+
+/**
+ * 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;
+
+       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,
+                                       td, offs);
+                       if (res)
+                               return res;
+                       offs += this->chipsize >> this->bbt_erase_shift;
+               }
+       } else {
+               res = read_bbt(mtd, buf, td->pages[0],
+                               mtd->size >> this->bbt_erase_shift, td, 0);
+               if (res)
+                       return res;
+       }
+       return 0;
+}
+
+/* BBT marker is in the first page, no OOB */
+static int scan_read_data(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
+                        struct nand_bbt_descr *td)
+{
+       size_t retlen;
+       size_t len;
+
+       len = td->len;
+       if (td->options & NAND_BBT_VERSION)
+               len++;
+
+       return mtd_read(mtd, offs, len, &retlen, buf);
+}
+
+/**
+ * scan_read_oob - [GENERIC] Scan data+OOB region to buffer
+ * @mtd: MTD device structure
+ * @buf: temporary buffer
+ * @offs: offset at which to scan
+ * @len: length of data region to read
+ *
+ * Scan read data from data+OOB. May traverse multiple pages, interleaving
+ * page,OOB,page,OOB,... in buf. Completes transfer and returns the "strongest"
+ * ECC condition (error or bitflip). May quit on the first (non-ECC) error.
+ */
+static int scan_read_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
+                        size_t len)
+{
+       struct mtd_oob_ops ops;
+       int res, ret = 0;
+
+       ops.mode = MTD_OPS_PLACE_OOB;
+       ops.ooboffs = 0;
+       ops.ooblen = mtd->oobsize;
+
+       while (len > 0) {
+               ops.datbuf = buf;
+               ops.len = min(len, (size_t)mtd->writesize);
+               ops.oobbuf = buf + ops.len;
+
+               res = mtd_read_oob(mtd, offs, &ops);
+               if (res) {
+                       if (!mtd_is_bitflip_or_eccerr(res))
+                               return res;
+                       else if (mtd_is_eccerr(res) || !ret)
+                               ret = res;
+               }
+
+               buf += mtd->oobsize + mtd->writesize;
+               len -= mtd->writesize;
+               offs += mtd->writesize;
+       }
+       return ret;
+}
+
+static int scan_read(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
+                        size_t len, struct nand_bbt_descr *td)
+{
+       if (td->options & NAND_BBT_NO_OOB)
+               return scan_read_data(mtd, buf, offs, td);
+       else
+               return scan_read_oob(mtd, buf, offs, len);
+}
+
+/* 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_OPS_PLACE_OOB;
+       ops.ooboffs = 0;
+       ops.ooblen = mtd->oobsize;
+       ops.datbuf = buf;
+       ops.oobbuf = oob;
+       ops.len = len;
+
+       return mtd_write_oob(mtd, offs, &ops);
+}
+
+static u32 bbt_get_ver_offs(struct mtd_info *mtd, struct nand_bbt_descr *td)
+{
+       u32 ver_offs = td->veroffs;
+
+       if (!(td->options & NAND_BBT_NO_OOB))
+               ver_offs += mtd->writesize;
+       return ver_offs;
+}
+
+/**
+ * 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 void 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(mtd, buf, (loff_t)td->pages[0] << this->page_shift,
+                             mtd->writesize, td);
+               td->version[0] = buf[bbt_get_ver_offs(mtd, td)];
+               pr_info("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(mtd, buf, (loff_t)md->pages[0] << this->page_shift,
+                             mtd->writesize, md);
+               md->version[0] = buf[bbt_get_ver_offs(mtd, md)];
+               pr_info("Bad block table at page %d, version 0x%02X\n",
+                        md->pages[0], md->version[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 numpages)
+{
+       struct mtd_oob_ops ops;
+       int j, ret;
+
+       ops.ooblen = mtd->oobsize;
+       ops.oobbuf = buf;
+       ops.ooboffs = 0;
+       ops.datbuf = NULL;
+       ops.mode = MTD_OPS_PLACE_OOB;
+
+       for (j = 0; j < numpages; 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);
+               /* Ignore ECC errors when checking for BBM */
+               if (ret && !mtd_is_bitflip_or_eccerr(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, numpages;
+       int startblock;
+       loff_t from;
+
+       pr_info("Scanning device for bad blocks\n");
+
+       if (bd->options & NAND_BBT_SCAN2NDPAGE)
+               numpages = 2;
+       else
+               numpages = 1;
+
+       if (chip == -1) {
+               numblocks = mtd->size >> this->bbt_erase_shift;
+               startblock = 0;
+               from = 0;
+       } else {
+               if (chip >= this->numchips) {
+                       pr_warn("create_bbt(): chipnr (%d) > available chips (%d)\n",
+                              chip + 1, this->numchips);
+                       return -EINVAL;
+               }
+               numblocks = this->chipsize >> this->bbt_erase_shift;
+               startblock = chip * numblocks;
+               numblocks += startblock;
+               from = (loff_t)startblock << this->bbt_erase_shift;
+       }
+
+       if (this->bbt_options & NAND_BBT_SCANLASTPAGE)
+               from += mtd->erasesize - (mtd->writesize * numpages);
+
+       for (i = startblock; i < numblocks; i++) {
+               int ret;
+
+               BUG_ON(bd->options & NAND_BBT_NO_OOB);
+
+               ret = scan_block_fast(mtd, bd, from, buf, numpages);
+               if (ret < 0)
+                       return ret;
+
+               if (ret) {
+                       bbt_mark_entry(this, i, BBT_BLOCK_FACTORY_BAD);
+                       pr_warn("Bad eraseblock %d at 0x%012llx\n",
+                               i, (unsigned long long)from);
+                       mtd->ecc_stats.badblocks++;
+               }
+
+               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 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;
+       }
+
+       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 = (loff_t)actblock << this->bbt_erase_shift;
+
+                       /* Read first page */
+                       scan_read(mtd, buf, offs, mtd->writesize, td);
+                       if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
+                               td->pages[i] = actblock << blocktopage;
+                               if (td->options & NAND_BBT_VERSION) {
+                                       offs = bbt_get_ver_offs(mtd, td);
+                                       td->version[i] = buf[offs];
+                               }
+                               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)
+                       pr_warn("Bad block table not found for chip %d\n", i);
+               else
+                       pr_info("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 void 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);
+}
+
+/**
+ * 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, res, chip = 0;
+       int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
+       int nrchips, 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_OPS_PLACE_OOB;
+
+       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 (bbt_get_entry(this, block)) {
+                       case BBT_BLOCK_WORN:
+                       case BBT_BLOCK_FACTORY_BAD:
+                               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;
+               }
+               pr_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;
+               }
+
+               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) {
+                                       pr_info("nand_bbt: error reading block for writing the bad block table\n");
+                                       return res;
+                               }
+                               pr_warn("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 if (td->options & NAND_BBT_NO_OOB) {
+                       ooboffs = 0;
+                       offs = td->len;
+                       /* The version byte */
+                       if (td->options & NAND_BBT_VERSION)
+                               offs++;
+                       /* Calc length */
+                       len = (size_t)(numblocks >> sft);
+                       len += offs;
+                       /* Make it page aligned! */
+                       len = ALIGN(len, mtd->writesize);
+                       /* Preset the buffer with 0xff */
+                       memset(buf, 0xff, len);
+                       /* Pattern is located at the begin of first page */
+                       memcpy(buf, td->pattern, td->len);
+               } else {
+                       /* Calc length */
+                       len = (size_t)(numblocks >> sft);
+                       /* Make it page aligned! */
+                       len = ALIGN(len, mtd->writesize);
+                       /* 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; i++) {
+                       uint8_t dat;
+                       int sftcnt = (i << (3 - sft)) & sftmsk;
+                       dat = bbt_get_entry(this, chip * numblocks + i);
+                       /* Do not store the reserved bbt blocks! */
+                       buf[offs + (i >> sft)] &= ~(msk[dat] << sftcnt);
+               }
+
+               memset(&einfo, 0, sizeof(einfo));
+               einfo.mtd = mtd;
+               einfo.addr = 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,
+                               td->options & NAND_BBT_NO_OOB ? NULL :
+                               &buf[len]);
+               if (res < 0)
+                       goto outerr;
+
+               pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
+                        (unsigned long long)to, td->version[chip]);
+
+               /* Mark it as used */
+               td->pages[chip] = page;
+       }
+       return 0;
+
+ outerr:
+       pr_warn("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;
+
+       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, create, chipsel, res, res2;
+       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;
+               create = 0;
+               rd = NULL;
+               rd2 = NULL;
+               res = res2 = 0;
+               /* Per chip or per device? */
+               chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
+               /* Mirrored table available? */
+               if (md) {
+                       if (td->pages[i] == -1 && md->pages[i] == -1) {
+                               create = 1;
+                               writeops = 0x03;
+                       } else if (td->pages[i] == -1) {
+                               rd = md;
+                               writeops = 0x01;
+                       } else if (md->pages[i] == -1) {
+                               rd = td;
+                               writeops = 0x02;
+                       } else if (td->version[i] == md->version[i]) {
+                               rd = td;
+                               if (!(td->options & NAND_BBT_VERSION))
+                                       rd2 = md;
+                       } else if (((int8_t)(td->version[i] - md->version[i])) > 0) {
+                               rd = td;
+                               writeops = 0x02;
+                       } else {
+                               rd = md;
+                               writeops = 0x01;
+                       }
+               } else {
+                       if (td->pages[i] == -1) {
+                               create = 1;
+                               writeops = 0x01;
+                       } else {
+                               rd = td;
+                       }
+               }
+
+               if (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) */
+                       if (!(this->bbt_options & NAND_BBT_CREATE_EMPTY))
+                               create_bbt(mtd, buf, bd, chipsel);
+
+                       td->version[i] = 1;
+                       if (md)
+                               md->version[i] = 1;
+               }
+
+               /* Read back first? */
+               if (rd) {
+                       res = read_abs_bbt(mtd, buf, rd, chipsel);
+                       if (mtd_is_eccerr(res)) {
+                               /* Mark table as invalid */
+                               rd->pages[i] = -1;
+                               rd->version[i] = 0;
+                               i--;
+                               continue;
+                       }
+               }
+               /* If they weren't versioned, read both */
+               if (rd2) {
+                       res2 = read_abs_bbt(mtd, buf, rd2, chipsel);
+                       if (mtd_is_eccerr(res2)) {
+                               /* Mark table as invalid */
+                               rd2->pages[i] = -1;
+                               rd2->version[i] = 0;
+                               i--;
+                               continue;
+                       }
+               }
+
+               /* Scrub the flash table(s)? */
+               if (mtd_is_bitflip(res) || mtd_is_bitflip(res2))
+                       writeops = 0x03;
+
+               /* Update version numbers before writing */
+               if (md) {
+                       td->version[i] = max(td->version[i], md->version[i]);
+                       md->version[i] = td->version[i];
+               }
+
+               /* 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;
+
+       /* 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);
+                       oldval = bbt_get_entry(this, block);
+                       bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
+                       if ((oldval != BBT_BLOCK_RESERVED) &&
+                                       td->reserved_block_code)
+                               nand_update_bbt(mtd, (loff_t)block <<
+                                               this->bbt_erase_shift);
+                       continue;
+               }
+               update = 0;
+               if (td->options & NAND_BBT_LASTBLOCK)
+                       block = ((i + 1) * nrblocks) - td->maxblocks;
+               else
+                       block = i * nrblocks;
+               for (j = 0; j < td->maxblocks; j++) {
+                       oldval = bbt_get_entry(this, block);
+                       bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
+                       if (oldval != BBT_BLOCK_RESERVED)
+                               update = 1;
+                       block++;
+               }
+               /*
+                * 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, (loff_t)(block - 1) <<
+                                       this->bbt_erase_shift);
+       }
+}
+
+/**
+ * verify_bbt_descr - verify the bad block description
+ * @mtd: MTD device structure
+ * @bd: the table to verify
+ *
+ * This functions performs a few sanity checks on the bad block description
+ * table.
+ */
+static void verify_bbt_descr(struct mtd_info *mtd, struct nand_bbt_descr *bd)
+{
+       struct nand_chip *this = mtd->priv;
+       u32 pattern_len;
+       u32 bits;
+       u32 table_size;
+
+       if (!bd)
+               return;
+
+       pattern_len = bd->len;
+       bits = bd->options & NAND_BBT_NRBITS_MSK;
+
+       BUG_ON((this->bbt_options & NAND_BBT_NO_OOB) &&
+                       !(this->bbt_options & NAND_BBT_USE_FLASH));
+       BUG_ON(!bits);
+
+       if (bd->options & NAND_BBT_VERSION)
+               pattern_len++;
+
+       if (bd->options & NAND_BBT_NO_OOB) {
+               BUG_ON(!(this->bbt_options & NAND_BBT_USE_FLASH));
+               BUG_ON(!(this->bbt_options & NAND_BBT_NO_OOB));
+               BUG_ON(bd->offs);
+               if (bd->options & NAND_BBT_VERSION)
+                       BUG_ON(bd->veroffs != bd->len);
+               BUG_ON(bd->options & NAND_BBT_SAVECONTENT);
+       }
+
+       if (bd->options & NAND_BBT_PERCHIP)
+               table_size = this->chipsize >> this->bbt_erase_shift;
+       else
+               table_size = mtd->size >> this->bbt_erase_shift;
+       table_size >>= 3;
+       table_size *= bits;
+       if (bd->options & NAND_BBT_NO_OOB)
+               table_size += pattern_len;
+       BUG_ON(table_size > (1 << this->bbt_erase_shift));
+}
+
+/**
+ * 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)
+               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))) {
+                       pr_err("nand_bbt: can't scan flash and build the RAM-based BBT\n");
+                       kfree(this->bbt);
+                       this->bbt = NULL;
+               }
+               return res;
+       }
+       verify_bbt_descr(mtd, td);
+       verify_bbt_descr(mtd, md);
+
+       /* 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) {
+               kfree(this->bbt);
+               this->bbt = NULL;
+               return -ENOMEM;
+       }
+
+       /* Is the bbt at a given page? */
+       if (td->options & NAND_BBT_ABSPAGE) {
+               read_abs_bbts(mtd, buf, td, md);
+       } else {
+               /* Search the bad block table using a pattern in oob */
+               search_read_bbts(mtd, buf, td, md);
+       }
+
+       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 - 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).
+ */
+static int nand_update_bbt(struct mtd_info *mtd, loff_t offs)
+{
+       struct nand_chip *this = mtd->priv;
+       int len, res = 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;
+
+       /* 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)
+               return -ENOMEM;
+
+       /* 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 (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 (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 };
+
+/* Generic flash bbt descriptors */
+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 = NAND_BBT_SCAN_MAXBLOCKS,
+       .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 = NAND_BBT_SCAN_MAXBLOCKS,
+       .pattern = mirror_pattern
+};
+
+static struct nand_bbt_descr bbt_main_no_oob_descr = {
+       .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
+               | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
+               | NAND_BBT_NO_OOB,
+       .len = 4,
+       .veroffs = 4,
+       .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
+       .pattern = bbt_pattern
+};
+
+static struct nand_bbt_descr bbt_mirror_no_oob_descr = {
+       .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
+               | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
+               | NAND_BBT_NO_OOB,
+       .len = 4,
+       .veroffs = 4,
+       .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
+       .pattern = mirror_pattern
+};
+
+#define BADBLOCK_SCAN_MASK (~NAND_BBT_NO_OOB)
+/**
+ * nand_create_badblock_pattern - [INTERN] Creates a BBT descriptor structure
+ * @this: NAND chip to create descriptor for
+ *
+ * This function allocates and initializes a nand_bbt_descr for BBM detection
+ * based on the properties of @this. The new descriptor is stored in
+ * this->badblock_pattern. Thus, this->badblock_pattern should be NULL when
+ * passed to this function.
+ */
+static int nand_create_badblock_pattern(struct nand_chip *this)
+{
+       struct nand_bbt_descr *bd;
+       if (this->badblock_pattern) {
+               pr_warn("Bad block pattern already allocated; not replacing\n");
+               return -EINVAL;
+       }
+       bd = kzalloc(sizeof(*bd), GFP_KERNEL);
+       if (!bd)
+               return -ENOMEM;
+       bd->options = this->bbt_options & BADBLOCK_SCAN_MASK;
+       bd->offs = this->badblockpos;
+       bd->len = (this->options & NAND_BUSWIDTH_16) ? 2 : 1;
+       bd->pattern = scan_ff_pattern;
+       bd->options |= NAND_BBT_DYNAMICSTRUCT;
+       this->badblock_pattern = bd;
+       return 0;
+}
+
+/**
+ * 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;
+       int ret;
+
+       /* Is a flash based bad block table requested? */
+       if (this->bbt_options & NAND_BBT_USE_FLASH) {
+               /* Use the default pattern descriptors */
+               if (!this->bbt_td) {
+                       if (this->bbt_options & NAND_BBT_NO_OOB) {
+                               this->bbt_td = &bbt_main_no_oob_descr;
+                               this->bbt_md = &bbt_mirror_no_oob_descr;
+                       } else {
+                               this->bbt_td = &bbt_main_descr;
+                               this->bbt_md = &bbt_mirror_descr;
+                       }
+               }
+       } else {
+               this->bbt_td = NULL;
+               this->bbt_md = NULL;
+       }
+
+       if (!this->badblock_pattern) {
+               ret = nand_create_badblock_pattern(this);
+               if (ret)
+                       return ret;
+       }
+
+       return nand_scan_bbt(mtd, this->badblock_pattern);
+}
+
+/**
+ * nand_isreserved_bbt - [NAND Interface] Check if a block is reserved
+ * @mtd: MTD device structure
+ * @offs: offset in the device
+ */
+int nand_isreserved_bbt(struct mtd_info *mtd, loff_t offs)
+{
+       struct nand_chip *this = mtd->priv;
+       int block;
+
+       block = (int)(offs >> this->bbt_erase_shift);
+       return bbt_get_entry(this, block) == BBT_BLOCK_RESERVED;
+}
+
+/**
+ * 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, res;
+
+       block = (int)(offs >> this->bbt_erase_shift);
+       res = bbt_get_entry(this, block);
+
+       pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
+                (unsigned int)offs, block, res);
+
+       switch (res) {
+       case BBT_BLOCK_GOOD:
+               return 0;
+       case BBT_BLOCK_WORN:
+               return 1;
+       case BBT_BLOCK_RESERVED:
+               return allowbbt ? 0 : 1;
+       }
+       return 1;
+}
+
+/**
+ * nand_markbad_bbt - [NAND Interface] Mark a block bad in the BBT
+ * @mtd: MTD device structure
+ * @offs: offset of the bad block
+ */
+int nand_markbad_bbt(struct mtd_info *mtd, loff_t offs)
+{
+       struct nand_chip *this = mtd->priv;
+       int block, ret = 0;
+
+       block = (int)(offs >> this->bbt_erase_shift);
+
+       /* Mark bad block in memory */
+       bbt_mark_entry(this, block, BBT_BLOCK_WORN);
+
+       /* Update flash-based bad block table */
+       if (this->bbt_options & NAND_BBT_USE_FLASH)
+               ret = nand_update_bbt(mtd, offs);
+
+       return ret;
+}
+
+EXPORT_SYMBOL(nand_scan_bbt);