root/drivers/mtd/nand/raw/nand_bbt.c

DEFINITIONS

1. bbt_get_entry
2. bbt_mark_entry
3. check_pattern_no_oob
4. check_pattern
5. check_short_pattern
6. add_marker_len
7. read_bbt
8. read_abs_bbt
9. scan_read_data
10. scan_read_oob
11. scan_read
12. scan_write_bbt
13. bbt_get_ver_offs
14. read_abs_bbts
15. scan_block_fast
16. create_bbt
17. search_bbt
18. search_read_bbts
19. get_bbt_block
20. mark_bbt_block_bad
21. write_bbt
22. nand_memory_bbt
23. check_create
24. nand_update_bbt
25. mark_bbt_region
26. verify_bbt_descr
27. nand_scan_bbt
28. nand_create_badblock_pattern
29. nand_create_bbt
30. nand_isreserved_bbt
31. nand_isbad_bbt
32. nand_markbad_bbt

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Overview:
   4  *   Bad block table support for the NAND driver
   5  *
   6  *  Copyright © 2004 Thomas Gleixner (tglx@linutronix.de)
   7  *
   8  * Description:
   9  *
  10  * When nand_scan_bbt is called, then it tries to find the bad block table
  11  * depending on the options in the BBT descriptor(s). If no flash based BBT
  12  * (NAND_BBT_USE_FLASH) is specified then the device is scanned for factory
  13  * marked good / bad blocks. This information is used to create a memory BBT.
  14  * Once a new bad block is discovered then the "factory" information is updated
  15  * on the device.
  16  * If a flash based BBT is specified then the function first tries to find the
  17  * BBT on flash. If a BBT is found then the contents are read and the memory
  18  * based BBT is created. If a mirrored BBT is selected then the mirror is
  19  * searched too and the versions are compared. If the mirror has a greater
  20  * version number, then the mirror BBT is used to build the memory based BBT.
  21  * If the tables are not versioned, then we "or" the bad block information.
  22  * If one of the BBTs is out of date or does not exist it is (re)created.
  23  * If no BBT exists at all then the device is scanned for factory marked
  24  * good / bad blocks and the bad block tables are created.
  25  *
  26  * For manufacturer created BBTs like the one found on M-SYS DOC devices
  27  * the BBT is searched and read but never created
  28  *
  29  * The auto generated bad block table is located in the last good blocks
  30  * of the device. The table is mirrored, so it can be updated eventually.
  31  * The table is marked in the OOB area with an ident pattern and a version
  32  * number which indicates which of both tables is more up to date. If the NAND
  33  * controller needs the complete OOB area for the ECC information then the
  34  * option NAND_BBT_NO_OOB should be used (along with NAND_BBT_USE_FLASH, of
  35  * course): it moves the ident pattern and the version byte into the data area
  36  * and the OOB area will remain untouched.
  37  *
  38  * The table uses 2 bits per block
  39  * 11b:         block is good
  40  * 00b:         block is factory marked bad
  41  * 01b, 10b:    block is marked bad due to wear
  42  *
  43  * The memory bad block table uses the following scheme:
  44  * 00b:         block is good
  45  * 01b:         block is marked bad due to wear
  46  * 10b:         block is reserved (to protect the bbt area)
  47  * 11b:         block is factory marked bad
  48  *
  49  * Multichip devices like DOC store the bad block info per floor.
  50  *
  51  * Following assumptions are made:
  52  * - bbts start at a page boundary, if autolocated on a block boundary
  53  * - the space necessary for a bbt in FLASH does not exceed a block boundary
  54  */
  55 
  56 #include <linux/slab.h>
  57 #include <linux/types.h>
  58 #include <linux/mtd/mtd.h>
  59 #include <linux/mtd/bbm.h>
  60 #include <linux/bitops.h>
  61 #include <linux/delay.h>
  62 #include <linux/vmalloc.h>
  63 #include <linux/export.h>
  64 #include <linux/string.h>
  65 
  66 #include "internals.h"
  67 
  68 #define BBT_BLOCK_GOOD          0x00
  69 #define BBT_BLOCK_WORN          0x01
  70 #define BBT_BLOCK_RESERVED      0x02
  71 #define BBT_BLOCK_FACTORY_BAD   0x03
  72 
  73 #define BBT_ENTRY_MASK          0x03
  74 #define BBT_ENTRY_SHIFT         2
  75 
  76 static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
  77 {
  78         uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
  79         entry >>= (block & BBT_ENTRY_MASK) * 2;
  80         return entry & BBT_ENTRY_MASK;
  81 }
  82 
  83 static inline void bbt_mark_entry(struct nand_chip *chip, int block,
  84                 uint8_t mark)
  85 {
  86         uint8_t msk = (mark & BBT_ENTRY_MASK) << ((block & BBT_ENTRY_MASK) * 2);
  87         chip->bbt[block >> BBT_ENTRY_SHIFT] |= msk;
  88 }
  89 
  90 static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
  91 {
  92         if (memcmp(buf, td->pattern, td->len))
  93                 return -1;
  94         return 0;
  95 }
  96 
  97 /**
  98  * check_pattern - [GENERIC] check if a pattern is in the buffer
  99  * @buf: the buffer to search
 100  * @len: the length of buffer to search
 101  * @paglen: the pagelength
 102  * @td: search pattern descriptor
 103  *
 104  * Check for a pattern at the given place. Used to search bad block tables and
 105  * good / bad block identifiers.
 106  */
 107 static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
 108 {
 109         if (td->options & NAND_BBT_NO_OOB)
 110                 return check_pattern_no_oob(buf, td);
 111 
 112         /* Compare the pattern */
 113         if (memcmp(buf + paglen + td->offs, td->pattern, td->len))
 114                 return -1;
 115 
 116         return 0;
 117 }
 118 
 119 /**
 120  * check_short_pattern - [GENERIC] check if a pattern is in the buffer
 121  * @buf: the buffer to search
 122  * @td: search pattern descriptor
 123  *
 124  * Check for a pattern at the given place. Used to search bad block tables and
 125  * good / bad block identifiers. Same as check_pattern, but no optional empty
 126  * check.
 127  */
 128 static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
 129 {
 130         /* Compare the pattern */
 131         if (memcmp(buf + td->offs, td->pattern, td->len))
 132                 return -1;
 133         return 0;
 134 }
 135 
 136 /**
 137  * add_marker_len - compute the length of the marker in data area
 138  * @td: BBT descriptor used for computation
 139  *
 140  * The length will be 0 if the marker is located in OOB area.
 141  */
 142 static u32 add_marker_len(struct nand_bbt_descr *td)
 143 {
 144         u32 len;
 145 
 146         if (!(td->options & NAND_BBT_NO_OOB))
 147                 return 0;
 148 
 149         len = td->len;
 150         if (td->options & NAND_BBT_VERSION)
 151                 len++;
 152         return len;
 153 }
 154 
 155 /**
 156  * read_bbt - [GENERIC] Read the bad block table starting from page
 157  * @this: NAND chip object
 158  * @buf: temporary buffer
 159  * @page: the starting page
 160  * @num: the number of bbt descriptors to read
 161  * @td: the bbt describtion table
 162  * @offs: block number offset in the table
 163  *
 164  * Read the bad block table starting from page.
 165  */
 166 static int read_bbt(struct nand_chip *this, uint8_t *buf, int page, int num,
 167                     struct nand_bbt_descr *td, int offs)
 168 {
 169         struct mtd_info *mtd = nand_to_mtd(this);
 170         int res, ret = 0, i, j, act = 0;
 171         size_t retlen, len, totlen;
 172         loff_t from;
 173         int bits = td->options & NAND_BBT_NRBITS_MSK;
 174         uint8_t msk = (uint8_t)((1 << bits) - 1);
 175         u32 marker_len;
 176         int reserved_block_code = td->reserved_block_code;
 177 
 178         totlen = (num * bits) >> 3;
 179         marker_len = add_marker_len(td);
 180         from = ((loff_t)page) << this->page_shift;
 181 
 182         while (totlen) {
 183                 len = min(totlen, (size_t)(1 << this->bbt_erase_shift));
 184                 if (marker_len) {
 185                         /*
 186                          * In case the BBT marker is not in the OOB area it
 187                          * will be just in the first page.
 188                          */
 189                         len -= marker_len;
 190                         from += marker_len;
 191                         marker_len = 0;
 192                 }
 193                 res = mtd_read(mtd, from, len, &retlen, buf);
 194                 if (res < 0) {
 195                         if (mtd_is_eccerr(res)) {
 196                                 pr_info("nand_bbt: ECC error in BBT at 0x%012llx\n",
 197                                         from & ~mtd->writesize);
 198                                 return res;
 199                         } else if (mtd_is_bitflip(res)) {
 200                                 pr_info("nand_bbt: corrected error in BBT at 0x%012llx\n",
 201                                         from & ~mtd->writesize);
 202                                 ret = res;
 203                         } else {
 204                                 pr_info("nand_bbt: error reading BBT\n");
 205                                 return res;
 206                         }
 207                 }
 208 
 209                 /* Analyse data */
 210                 for (i = 0; i < len; i++) {
 211                         uint8_t dat = buf[i];
 212                         for (j = 0; j < 8; j += bits, act++) {
 213                                 uint8_t tmp = (dat >> j) & msk;
 214                                 if (tmp == msk)
 215                                         continue;
 216                                 if (reserved_block_code && (tmp == reserved_block_code)) {
 217                                         pr_info("nand_read_bbt: reserved block at 0x%012llx\n",
 218                                                  (loff_t)(offs + act) <<
 219                                                  this->bbt_erase_shift);
 220                                         bbt_mark_entry(this, offs + act,
 221                                                         BBT_BLOCK_RESERVED);
 222                                         mtd->ecc_stats.bbtblocks++;
 223                                         continue;
 224                                 }
 225                                 /*
 226                                  * Leave it for now, if it's matured we can
 227                                  * move this message to pr_debug.
 228                                  */
 229                                 pr_info("nand_read_bbt: bad block at 0x%012llx\n",
 230                                          (loff_t)(offs + act) <<
 231                                          this->bbt_erase_shift);
 232                                 /* Factory marked bad or worn out? */
 233                                 if (tmp == 0)
 234                                         bbt_mark_entry(this, offs + act,
 235                                                         BBT_BLOCK_FACTORY_BAD);
 236                                 else
 237                                         bbt_mark_entry(this, offs + act,
 238                                                         BBT_BLOCK_WORN);
 239                                 mtd->ecc_stats.badblocks++;
 240                         }
 241                 }
 242                 totlen -= len;
 243                 from += len;
 244         }
 245         return ret;
 246 }
 247 
 248 /**
 249  * read_abs_bbt - [GENERIC] Read the bad block table starting at a given page
 250  * @this: NAND chip object
 251  * @buf: temporary buffer
 252  * @td: descriptor for the bad block table
 253  * @chip: read the table for a specific chip, -1 read all chips; applies only if
 254  *        NAND_BBT_PERCHIP option is set
 255  *
 256  * Read the bad block table for all chips starting at a given page. We assume
 257  * that the bbt bits are in consecutive order.
 258  */
 259 static int read_abs_bbt(struct nand_chip *this, uint8_t *buf,
 260                         struct nand_bbt_descr *td, int chip)
 261 {
 262         struct mtd_info *mtd = nand_to_mtd(this);
 263         u64 targetsize = nanddev_target_size(&this->base);
 264         int res = 0, i;
 265 
 266         if (td->options & NAND_BBT_PERCHIP) {
 267                 int offs = 0;
 268                 for (i = 0; i < nanddev_ntargets(&this->base); i++) {
 269                         if (chip == -1 || chip == i)
 270                                 res = read_bbt(this, buf, td->pages[i],
 271                                         targetsize >> this->bbt_erase_shift,
 272                                         td, offs);
 273                         if (res)
 274                                 return res;
 275                         offs += targetsize >> this->bbt_erase_shift;
 276                 }
 277         } else {
 278                 res = read_bbt(this, buf, td->pages[0],
 279                                 mtd->size >> this->bbt_erase_shift, td, 0);
 280                 if (res)
 281                         return res;
 282         }
 283         return 0;
 284 }
 285 
 286 /* BBT marker is in the first page, no OOB */
 287 static int scan_read_data(struct nand_chip *this, uint8_t *buf, loff_t offs,
 288                           struct nand_bbt_descr *td)
 289 {
 290         struct mtd_info *mtd = nand_to_mtd(this);
 291         size_t retlen;
 292         size_t len;
 293 
 294         len = td->len;
 295         if (td->options & NAND_BBT_VERSION)
 296                 len++;
 297 
 298         return mtd_read(mtd, offs, len, &retlen, buf);
 299 }
 300 
 301 /**
 302  * scan_read_oob - [GENERIC] Scan data+OOB region to buffer
 303  * @this: NAND chip object
 304  * @buf: temporary buffer
 305  * @offs: offset at which to scan
 306  * @len: length of data region to read
 307  *
 308  * Scan read data from data+OOB. May traverse multiple pages, interleaving
 309  * page,OOB,page,OOB,... in buf. Completes transfer and returns the "strongest"
 310  * ECC condition (error or bitflip). May quit on the first (non-ECC) error.
 311  */
 312 static int scan_read_oob(struct nand_chip *this, uint8_t *buf, loff_t offs,
 313                          size_t len)
 314 {
 315         struct mtd_info *mtd = nand_to_mtd(this);
 316         struct mtd_oob_ops ops;
 317         int res, ret = 0;
 318 
 319         ops.mode = MTD_OPS_PLACE_OOB;
 320         ops.ooboffs = 0;
 321         ops.ooblen = mtd->oobsize;
 322 
 323         while (len > 0) {
 324                 ops.datbuf = buf;
 325                 ops.len = min(len, (size_t)mtd->writesize);
 326                 ops.oobbuf = buf + ops.len;
 327 
 328                 res = mtd_read_oob(mtd, offs, &ops);
 329                 if (res) {
 330                         if (!mtd_is_bitflip_or_eccerr(res))
 331                                 return res;
 332                         else if (mtd_is_eccerr(res) || !ret)
 333                                 ret = res;
 334                 }
 335 
 336                 buf += mtd->oobsize + mtd->writesize;
 337                 len -= mtd->writesize;
 338                 offs += mtd->writesize;
 339         }
 340         return ret;
 341 }
 342 
 343 static int scan_read(struct nand_chip *this, uint8_t *buf, loff_t offs,
 344                      size_t len, struct nand_bbt_descr *td)
 345 {
 346         if (td->options & NAND_BBT_NO_OOB)
 347                 return scan_read_data(this, buf, offs, td);
 348         else
 349                 return scan_read_oob(this, buf, offs, len);
 350 }
 351 
 352 /* Scan write data with oob to flash */
 353 static int scan_write_bbt(struct nand_chip *this, loff_t offs, size_t len,
 354                           uint8_t *buf, uint8_t *oob)
 355 {
 356         struct mtd_info *mtd = nand_to_mtd(this);
 357         struct mtd_oob_ops ops;
 358 
 359         ops.mode = MTD_OPS_PLACE_OOB;
 360         ops.ooboffs = 0;
 361         ops.ooblen = mtd->oobsize;
 362         ops.datbuf = buf;
 363         ops.oobbuf = oob;
 364         ops.len = len;
 365 
 366         return mtd_write_oob(mtd, offs, &ops);
 367 }
 368 
 369 static u32 bbt_get_ver_offs(struct nand_chip *this, struct nand_bbt_descr *td)
 370 {
 371         struct mtd_info *mtd = nand_to_mtd(this);
 372         u32 ver_offs = td->veroffs;
 373 
 374         if (!(td->options & NAND_BBT_NO_OOB))
 375                 ver_offs += mtd->writesize;
 376         return ver_offs;
 377 }
 378 
 379 /**
 380  * read_abs_bbts - [GENERIC] Read the bad block table(s) for all chips starting at a given page
 381  * @this: NAND chip object
 382  * @buf: temporary buffer
 383  * @td: descriptor for the bad block table
 384  * @md: descriptor for the bad block table mirror
 385  *
 386  * Read the bad block table(s) for all chips starting at a given page. We
 387  * assume that the bbt bits are in consecutive order.
 388  */
 389 static void read_abs_bbts(struct nand_chip *this, uint8_t *buf,
 390                           struct nand_bbt_descr *td, struct nand_bbt_descr *md)
 391 {
 392         struct mtd_info *mtd = nand_to_mtd(this);
 393 
 394         /* Read the primary version, if available */
 395         if (td->options & NAND_BBT_VERSION) {
 396                 scan_read(this, buf, (loff_t)td->pages[0] << this->page_shift,
 397                           mtd->writesize, td);
 398                 td->version[0] = buf[bbt_get_ver_offs(this, td)];
 399                 pr_info("Bad block table at page %d, version 0x%02X\n",
 400                          td->pages[0], td->version[0]);
 401         }
 402 
 403         /* Read the mirror version, if available */
 404         if (md && (md->options & NAND_BBT_VERSION)) {
 405                 scan_read(this, buf, (loff_t)md->pages[0] << this->page_shift,
 406                           mtd->writesize, md);
 407                 md->version[0] = buf[bbt_get_ver_offs(this, md)];
 408                 pr_info("Bad block table at page %d, version 0x%02X\n",
 409                          md->pages[0], md->version[0]);
 410         }
 411 }
 412 
 413 /* Scan a given block partially */
 414 static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
 415                            loff_t offs, uint8_t *buf)
 416 {
 417         struct mtd_info *mtd = nand_to_mtd(this);
 418 
 419         struct mtd_oob_ops ops;
 420         int ret, page_offset;
 421 
 422         ops.ooblen = mtd->oobsize;
 423         ops.oobbuf = buf;
 424         ops.ooboffs = 0;
 425         ops.datbuf = NULL;
 426         ops.mode = MTD_OPS_PLACE_OOB;
 427 
 428         page_offset = nand_bbm_get_next_page(this, 0);
 429 
 430         while (page_offset >= 0) {
 431                 /*
 432                  * Read the full oob until read_oob is fixed to handle single
 433                  * byte reads for 16 bit buswidth.
 434                  */
 435                 ret = mtd_read_oob(mtd, offs + (page_offset * mtd->writesize),
 436                                    &ops);
 437                 /* Ignore ECC errors when checking for BBM */
 438                 if (ret && !mtd_is_bitflip_or_eccerr(ret))
 439                         return ret;
 440 
 441                 if (check_short_pattern(buf, bd))
 442                         return 1;
 443 
 444                 page_offset = nand_bbm_get_next_page(this, page_offset + 1);
 445         }
 446 
 447         return 0;
 448 }
 449 
 450 /**
 451  * create_bbt - [GENERIC] Create a bad block table by scanning the device
 452  * @this: NAND chip object
 453  * @buf: temporary buffer
 454  * @bd: descriptor for the good/bad block search pattern
 455  * @chip: create the table for a specific chip, -1 read all chips; applies only
 456  *        if NAND_BBT_PERCHIP option is set
 457  *
 458  * Create a bad block table by scanning the device for the given good/bad block
 459  * identify pattern.
 460  */
 461 static int create_bbt(struct nand_chip *this, uint8_t *buf,
 462                       struct nand_bbt_descr *bd, int chip)
 463 {
 464         u64 targetsize = nanddev_target_size(&this->base);
 465         struct mtd_info *mtd = nand_to_mtd(this);
 466         int i, numblocks, startblock;
 467         loff_t from;
 468 
 469         pr_info("Scanning device for bad blocks\n");
 470 
 471         if (chip == -1) {
 472                 numblocks = mtd->size >> this->bbt_erase_shift;
 473                 startblock = 0;
 474                 from = 0;
 475         } else {
 476                 if (chip >= nanddev_ntargets(&this->base)) {
 477                         pr_warn("create_bbt(): chipnr (%d) > available chips (%d)\n",
 478                                 chip + 1, nanddev_ntargets(&this->base));
 479                         return -EINVAL;
 480                 }
 481                 numblocks = targetsize >> this->bbt_erase_shift;
 482                 startblock = chip * numblocks;
 483                 numblocks += startblock;
 484                 from = (loff_t)startblock << this->bbt_erase_shift;
 485         }
 486 
 487         for (i = startblock; i < numblocks; i++) {
 488                 int ret;
 489 
 490                 BUG_ON(bd->options & NAND_BBT_NO_OOB);
 491 
 492                 ret = scan_block_fast(this, bd, from, buf);
 493                 if (ret < 0)
 494                         return ret;
 495 
 496                 if (ret) {
 497                         bbt_mark_entry(this, i, BBT_BLOCK_FACTORY_BAD);
 498                         pr_warn("Bad eraseblock %d at 0x%012llx\n",
 499                                 i, (unsigned long long)from);
 500                         mtd->ecc_stats.badblocks++;
 501                 }
 502 
 503                 from += (1 << this->bbt_erase_shift);
 504         }
 505         return 0;
 506 }
 507 
 508 /**
 509  * search_bbt - [GENERIC] scan the device for a specific bad block table
 510  * @this: NAND chip object
 511  * @buf: temporary buffer
 512  * @td: descriptor for the bad block table
 513  *
 514  * Read the bad block table by searching for a given ident pattern. Search is
 515  * preformed either from the beginning up or from the end of the device
 516  * downwards. The search starts always at the start of a block. If the option
 517  * NAND_BBT_PERCHIP is given, each chip is searched for a bbt, which contains
 518  * the bad block information of this chip. This is necessary to provide support
 519  * for certain DOC devices.
 520  *
 521  * The bbt ident pattern resides in the oob area of the first page in a block.
 522  */
 523 static int search_bbt(struct nand_chip *this, uint8_t *buf,
 524                       struct nand_bbt_descr *td)
 525 {
 526         u64 targetsize = nanddev_target_size(&this->base);
 527         struct mtd_info *mtd = nand_to_mtd(this);
 528         int i, chips;
 529         int startblock, block, dir;
 530         int scanlen = mtd->writesize + mtd->oobsize;
 531         int bbtblocks;
 532         int blocktopage = this->bbt_erase_shift - this->page_shift;
 533 
 534         /* Search direction top -> down? */
 535         if (td->options & NAND_BBT_LASTBLOCK) {
 536                 startblock = (mtd->size >> this->bbt_erase_shift) - 1;
 537                 dir = -1;
 538         } else {
 539                 startblock = 0;
 540                 dir = 1;
 541         }
 542 
 543         /* Do we have a bbt per chip? */
 544         if (td->options & NAND_BBT_PERCHIP) {
 545                 chips = nanddev_ntargets(&this->base);
 546                 bbtblocks = targetsize >> this->bbt_erase_shift;
 547                 startblock &= bbtblocks - 1;
 548         } else {
 549                 chips = 1;
 550                 bbtblocks = mtd->size >> this->bbt_erase_shift;
 551         }
 552 
 553         for (i = 0; i < chips; i++) {
 554                 /* Reset version information */
 555                 td->version[i] = 0;
 556                 td->pages[i] = -1;
 557                 /* Scan the maximum number of blocks */
 558                 for (block = 0; block < td->maxblocks; block++) {
 559 
 560                         int actblock = startblock + dir * block;
 561                         loff_t offs = (loff_t)actblock << this->bbt_erase_shift;
 562 
 563                         /* Read first page */
 564                         scan_read(this, buf, offs, mtd->writesize, td);
 565                         if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
 566                                 td->pages[i] = actblock << blocktopage;
 567                                 if (td->options & NAND_BBT_VERSION) {
 568                                         offs = bbt_get_ver_offs(this, td);
 569                                         td->version[i] = buf[offs];
 570                                 }
 571                                 break;
 572                         }
 573                 }
 574                 startblock += targetsize >> this->bbt_erase_shift;
 575         }
 576         /* Check, if we found a bbt for each requested chip */
 577         for (i = 0; i < chips; i++) {
 578                 if (td->pages[i] == -1)
 579                         pr_warn("Bad block table not found for chip %d\n", i);
 580                 else
 581                         pr_info("Bad block table found at page %d, version 0x%02X\n",
 582                                 td->pages[i], td->version[i]);
 583         }
 584         return 0;
 585 }
 586 
 587 /**
 588  * search_read_bbts - [GENERIC] scan the device for bad block table(s)
 589  * @this: NAND chip object
 590  * @buf: temporary buffer
 591  * @td: descriptor for the bad block table
 592  * @md: descriptor for the bad block table mirror
 593  *
 594  * Search and read the bad block table(s).
 595  */
 596 static void search_read_bbts(struct nand_chip *this, uint8_t *buf,
 597                              struct nand_bbt_descr *td,
 598                              struct nand_bbt_descr *md)
 599 {
 600         /* Search the primary table */
 601         search_bbt(this, buf, td);
 602 
 603         /* Search the mirror table */
 604         if (md)
 605                 search_bbt(this, buf, md);
 606 }
 607 
 608 /**
 609  * get_bbt_block - Get the first valid eraseblock suitable to store a BBT
 610  * @this: the NAND device
 611  * @td: the BBT description
 612  * @md: the mirror BBT descriptor
 613  * @chip: the CHIP selector
 614  *
 615  * This functions returns a positive block number pointing a valid eraseblock
 616  * suitable to store a BBT (i.e. in the range reserved for BBT), or -ENOSPC if
 617  * all blocks are already used of marked bad. If td->pages[chip] was already
 618  * pointing to a valid block we re-use it, otherwise we search for the next
 619  * valid one.
 620  */
 621 static int get_bbt_block(struct nand_chip *this, struct nand_bbt_descr *td,
 622                          struct nand_bbt_descr *md, int chip)
 623 {
 624         u64 targetsize = nanddev_target_size(&this->base);
 625         int startblock, dir, page, numblocks, i;
 626 
 627         /*
 628          * There was already a version of the table, reuse the page. This
 629          * applies for absolute placement too, as we have the page number in
 630          * td->pages.
 631          */
 632         if (td->pages[chip] != -1)
 633                 return td->pages[chip] >>
 634                                 (this->bbt_erase_shift - this->page_shift);
 635 
 636         numblocks = (int)(targetsize >> this->bbt_erase_shift);
 637         if (!(td->options & NAND_BBT_PERCHIP))
 638                 numblocks *= nanddev_ntargets(&this->base);
 639 
 640         /*
 641          * Automatic placement of the bad block table. Search direction
 642          * top -> down?
 643          */
 644         if (td->options & NAND_BBT_LASTBLOCK) {
 645                 startblock = numblocks * (chip + 1) - 1;
 646                 dir = -1;
 647         } else {
 648                 startblock = chip * numblocks;
 649                 dir = 1;
 650         }
 651 
 652         for (i = 0; i < td->maxblocks; i++) {
 653                 int block = startblock + dir * i;
 654 
 655                 /* Check, if the block is bad */
 656                 switch (bbt_get_entry(this, block)) {
 657                 case BBT_BLOCK_WORN:
 658                 case BBT_BLOCK_FACTORY_BAD:
 659                         continue;
 660                 }
 661 
 662                 page = block << (this->bbt_erase_shift - this->page_shift);
 663 
 664                 /* Check, if the block is used by the mirror table */
 665                 if (!md || md->pages[chip] != page)
 666                         return block;
 667         }
 668 
 669         return -ENOSPC;
 670 }
 671 
 672 /**
 673  * mark_bbt_block_bad - Mark one of the block reserved for BBT bad
 674  * @this: the NAND device
 675  * @td: the BBT description
 676  * @chip: the CHIP selector
 677  * @block: the BBT block to mark
 678  *
 679  * Blocks reserved for BBT can become bad. This functions is an helper to mark
 680  * such blocks as bad. It takes care of updating the in-memory BBT, marking the
 681  * block as bad using a bad block marker and invalidating the associated
 682  * td->pages[] entry.
 683  */
 684 static void mark_bbt_block_bad(struct nand_chip *this,
 685                                struct nand_bbt_descr *td,
 686                                int chip, int block)
 687 {
 688         loff_t to;
 689         int res;
 690 
 691         bbt_mark_entry(this, block, BBT_BLOCK_WORN);
 692 
 693         to = (loff_t)block << this->bbt_erase_shift;
 694         res = nand_markbad_bbm(this, to);
 695         if (res)
 696                 pr_warn("nand_bbt: error %d while marking block %d bad\n",
 697                         res, block);
 698 
 699         td->pages[chip] = -1;
 700 }
 701 
 702 /**
 703  * write_bbt - [GENERIC] (Re)write the bad block table
 704  * @this: NAND chip object
 705  * @buf: temporary buffer
 706  * @td: descriptor for the bad block table
 707  * @md: descriptor for the bad block table mirror
 708  * @chipsel: selector for a specific chip, -1 for all
 709  *
 710  * (Re)write the bad block table.
 711  */
 712 static int write_bbt(struct nand_chip *this, uint8_t *buf,
 713                      struct nand_bbt_descr *td, struct nand_bbt_descr *md,
 714                      int chipsel)
 715 {
 716         u64 targetsize = nanddev_target_size(&this->base);
 717         struct mtd_info *mtd = nand_to_mtd(this);
 718         struct erase_info einfo;
 719         int i, res, chip = 0;
 720         int bits, page, offs, numblocks, sft, sftmsk;
 721         int nrchips, pageoffs, ooboffs;
 722         uint8_t msk[4];
 723         uint8_t rcode = td->reserved_block_code;
 724         size_t retlen, len = 0;
 725         loff_t to;
 726         struct mtd_oob_ops ops;
 727 
 728         ops.ooblen = mtd->oobsize;
 729         ops.ooboffs = 0;
 730         ops.datbuf = NULL;
 731         ops.mode = MTD_OPS_PLACE_OOB;
 732 
 733         if (!rcode)
 734                 rcode = 0xff;
 735         /* Write bad block table per chip rather than per device? */
 736         if (td->options & NAND_BBT_PERCHIP) {
 737                 numblocks = (int)(targetsize >> this->bbt_erase_shift);
 738                 /* Full device write or specific chip? */
 739                 if (chipsel == -1) {
 740                         nrchips = nanddev_ntargets(&this->base);
 741                 } else {
 742                         nrchips = chipsel + 1;
 743                         chip = chipsel;
 744                 }
 745         } else {
 746                 numblocks = (int)(mtd->size >> this->bbt_erase_shift);
 747                 nrchips = 1;
 748         }
 749 
 750         /* Loop through the chips */
 751         while (chip < nrchips) {
 752                 int block;
 753 
 754                 block = get_bbt_block(this, td, md, chip);
 755                 if (block < 0) {
 756                         pr_err("No space left to write bad block table\n");
 757                         res = block;
 758                         goto outerr;
 759                 }
 760 
 761                 /*
 762                  * get_bbt_block() returns a block number, shift the value to
 763                  * get a page number.
 764                  */
 765                 page = block << (this->bbt_erase_shift - this->page_shift);
 766 
 767                 /* Set up shift count and masks for the flash table */
 768                 bits = td->options & NAND_BBT_NRBITS_MSK;
 769                 msk[2] = ~rcode;
 770                 switch (bits) {
 771                 case 1: sft = 3; sftmsk = 0x07; msk[0] = 0x00; msk[1] = 0x01;
 772                         msk[3] = 0x01;
 773                         break;
 774                 case 2: sft = 2; sftmsk = 0x06; msk[0] = 0x00; msk[1] = 0x01;
 775                         msk[3] = 0x03;
 776                         break;
 777                 case 4: sft = 1; sftmsk = 0x04; msk[0] = 0x00; msk[1] = 0x0C;
 778                         msk[3] = 0x0f;
 779                         break;
 780                 case 8: sft = 0; sftmsk = 0x00; msk[0] = 0x00; msk[1] = 0x0F;
 781                         msk[3] = 0xff;
 782                         break;
 783                 default: return -EINVAL;
 784                 }
 785 
 786                 to = ((loff_t)page) << this->page_shift;
 787 
 788                 /* Must we save the block contents? */
 789                 if (td->options & NAND_BBT_SAVECONTENT) {
 790                         /* Make it block aligned */
 791                         to &= ~(((loff_t)1 << this->bbt_erase_shift) - 1);
 792                         len = 1 << this->bbt_erase_shift;
 793                         res = mtd_read(mtd, to, len, &retlen, buf);
 794                         if (res < 0) {
 795                                 if (retlen != len) {
 796                                         pr_info("nand_bbt: error reading block for writing the bad block table\n");
 797                                         return res;
 798                                 }
 799                                 pr_warn("nand_bbt: ECC error while reading block for writing bad block table\n");
 800                         }
 801                         /* Read oob data */
 802                         ops.ooblen = (len >> this->page_shift) * mtd->oobsize;
 803                         ops.oobbuf = &buf[len];
 804                         res = mtd_read_oob(mtd, to + mtd->writesize, &ops);
 805                         if (res < 0 || ops.oobretlen != ops.ooblen)
 806                                 goto outerr;
 807 
 808                         /* Calc the byte offset in the buffer */
 809                         pageoffs = page - (int)(to >> this->page_shift);
 810                         offs = pageoffs << this->page_shift;
 811                         /* Preset the bbt area with 0xff */
 812                         memset(&buf[offs], 0xff, (size_t)(numblocks >> sft));
 813                         ooboffs = len + (pageoffs * mtd->oobsize);
 814 
 815                 } else if (td->options & NAND_BBT_NO_OOB) {
 816                         ooboffs = 0;
 817                         offs = td->len;
 818                         /* The version byte */
 819                         if (td->options & NAND_BBT_VERSION)
 820                                 offs++;
 821                         /* Calc length */
 822                         len = (size_t)(numblocks >> sft);
 823                         len += offs;
 824                         /* Make it page aligned! */
 825                         len = ALIGN(len, mtd->writesize);
 826                         /* Preset the buffer with 0xff */
 827                         memset(buf, 0xff, len);
 828                         /* Pattern is located at the begin of first page */
 829                         memcpy(buf, td->pattern, td->len);
 830                 } else {
 831                         /* Calc length */
 832                         len = (size_t)(numblocks >> sft);
 833                         /* Make it page aligned! */
 834                         len = ALIGN(len, mtd->writesize);
 835                         /* Preset the buffer with 0xff */
 836                         memset(buf, 0xff, len +
 837                                (len >> this->page_shift)* mtd->oobsize);
 838                         offs = 0;
 839                         ooboffs = len;
 840                         /* Pattern is located in oob area of first page */
 841                         memcpy(&buf[ooboffs + td->offs], td->pattern, td->len);
 842                 }
 843 
 844                 if (td->options & NAND_BBT_VERSION)
 845                         buf[ooboffs + td->veroffs] = td->version[chip];
 846 
 847                 /* Walk through the memory table */
 848                 for (i = 0; i < numblocks; i++) {
 849                         uint8_t dat;
 850                         int sftcnt = (i << (3 - sft)) & sftmsk;
 851                         dat = bbt_get_entry(this, chip * numblocks + i);
 852                         /* Do not store the reserved bbt blocks! */
 853                         buf[offs + (i >> sft)] &= ~(msk[dat] << sftcnt);
 854                 }
 855 
 856                 memset(&einfo, 0, sizeof(einfo));
 857                 einfo.addr = to;
 858                 einfo.len = 1 << this->bbt_erase_shift;
 859                 res = nand_erase_nand(this, &einfo, 1);
 860                 if (res < 0) {
 861                         pr_warn("nand_bbt: error while erasing BBT block %d\n",
 862                                 res);
 863                         mark_bbt_block_bad(this, td, chip, block);
 864                         continue;
 865                 }
 866 
 867                 res = scan_write_bbt(this, to, len, buf,
 868                                      td->options & NAND_BBT_NO_OOB ?
 869                                      NULL : &buf[len]);
 870                 if (res < 0) {
 871                         pr_warn("nand_bbt: error while writing BBT block %d\n",
 872                                 res);
 873                         mark_bbt_block_bad(this, td, chip, block);
 874                         continue;
 875                 }
 876 
 877                 pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
 878                          (unsigned long long)to, td->version[chip]);
 879 
 880                 /* Mark it as used */
 881                 td->pages[chip++] = page;
 882         }
 883         return 0;
 884 
 885  outerr:
 886         pr_warn("nand_bbt: error while writing bad block table %d\n", res);
 887         return res;
 888 }
 889 
 890 /**
 891  * nand_memory_bbt - [GENERIC] create a memory based bad block table
 892  * @this: NAND chip object
 893  * @bd: descriptor for the good/bad block search pattern
 894  *
 895  * The function creates a memory based bbt by scanning the device for
 896  * manufacturer / software marked good / bad blocks.
 897  */
 898 static inline int nand_memory_bbt(struct nand_chip *this,
 899                                   struct nand_bbt_descr *bd)
 900 {
 901         u8 *pagebuf = nand_get_data_buf(this);
 902 
 903         return create_bbt(this, pagebuf, bd, -1);
 904 }
 905 
 906 /**
 907  * check_create - [GENERIC] create and write bbt(s) if necessary
 908  * @this: the NAND device
 909  * @buf: temporary buffer
 910  * @bd: descriptor for the good/bad block search pattern
 911  *
 912  * The function checks the results of the previous call to read_bbt and creates
 913  * / updates the bbt(s) if necessary. Creation is necessary if no bbt was found
 914  * for the chip/device. Update is necessary if one of the tables is missing or
 915  * the version nr. of one table is less than the other.
 916  */
 917 static int check_create(struct nand_chip *this, uint8_t *buf,
 918                         struct nand_bbt_descr *bd)
 919 {
 920         int i, chips, writeops, create, chipsel, res, res2;
 921         struct nand_bbt_descr *td = this->bbt_td;
 922         struct nand_bbt_descr *md = this->bbt_md;
 923         struct nand_bbt_descr *rd, *rd2;
 924 
 925         /* Do we have a bbt per chip? */
 926         if (td->options & NAND_BBT_PERCHIP)
 927                 chips = nanddev_ntargets(&this->base);
 928         else
 929                 chips = 1;
 930 
 931         for (i = 0; i < chips; i++) {
 932                 writeops = 0;
 933                 create = 0;
 934                 rd = NULL;
 935                 rd2 = NULL;
 936                 res = res2 = 0;
 937                 /* Per chip or per device? */
 938                 chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
 939                 /* Mirrored table available? */
 940                 if (md) {
 941                         if (td->pages[i] == -1 && md->pages[i] == -1) {
 942                                 create = 1;
 943                                 writeops = 0x03;
 944                         } else if (td->pages[i] == -1) {
 945                                 rd = md;
 946                                 writeops = 0x01;
 947                         } else if (md->pages[i] == -1) {
 948                                 rd = td;
 949                                 writeops = 0x02;
 950                         } else if (td->version[i] == md->version[i]) {
 951                                 rd = td;
 952                                 if (!(td->options & NAND_BBT_VERSION))
 953                                         rd2 = md;
 954                         } else if (((int8_t)(td->version[i] - md->version[i])) > 0) {
 955                                 rd = td;
 956                                 writeops = 0x02;
 957                         } else {
 958                                 rd = md;
 959                                 writeops = 0x01;
 960                         }
 961                 } else {
 962                         if (td->pages[i] == -1) {
 963                                 create = 1;
 964                                 writeops = 0x01;
 965                         } else {
 966                                 rd = td;
 967                         }
 968                 }
 969 
 970                 if (create) {
 971                         /* Create the bad block table by scanning the device? */
 972                         if (!(td->options & NAND_BBT_CREATE))
 973                                 continue;
 974 
 975                         /* Create the table in memory by scanning the chip(s) */
 976                         if (!(this->bbt_options & NAND_BBT_CREATE_EMPTY))
 977                                 create_bbt(this, buf, bd, chipsel);
 978 
 979                         td->version[i] = 1;
 980                         if (md)
 981                                 md->version[i] = 1;
 982                 }
 983 
 984                 /* Read back first? */
 985                 if (rd) {
 986                         res = read_abs_bbt(this, buf, rd, chipsel);
 987                         if (mtd_is_eccerr(res)) {
 988                                 /* Mark table as invalid */
 989                                 rd->pages[i] = -1;
 990                                 rd->version[i] = 0;
 991                                 i--;
 992                                 continue;
 993                         }
 994                 }
 995                 /* If they weren't versioned, read both */
 996                 if (rd2) {
 997                         res2 = read_abs_bbt(this, buf, rd2, chipsel);
 998                         if (mtd_is_eccerr(res2)) {
 999                                 /* Mark table as invalid */
1000                                 rd2->pages[i] = -1;
1001                                 rd2->version[i] = 0;
1002                                 i--;
1003                                 continue;
1004                         }
1005                 }
1006 
1007                 /* Scrub the flash table(s)? */
1008                 if (mtd_is_bitflip(res) || mtd_is_bitflip(res2))
1009                         writeops = 0x03;
1010 
1011                 /* Update version numbers before writing */
1012                 if (md) {
1013                         td->version[i] = max(td->version[i], md->version[i]);
1014                         md->version[i] = td->version[i];
1015                 }
1016 
1017                 /* Write the bad block table to the device? */
1018                 if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
1019                         res = write_bbt(this, buf, td, md, chipsel);
1020                         if (res < 0)
1021                                 return res;
1022                 }
1023 
1024                 /* Write the mirror bad block table to the device? */
1025                 if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
1026                         res = write_bbt(this, buf, md, td, chipsel);
1027                         if (res < 0)
1028                                 return res;
1029                 }
1030         }
1031         return 0;
1032 }
1033 
1034 /**
1035  * nand_update_bbt - update bad block table(s)
1036  * @this: the NAND device
1037  * @offs: the offset of the newly marked block
1038  *
1039  * The function updates the bad block table(s).
1040  */
1041 static int nand_update_bbt(struct nand_chip *this, loff_t offs)
1042 {
1043         struct mtd_info *mtd = nand_to_mtd(this);
1044         int len, res = 0;
1045         int chip, chipsel;
1046         uint8_t *buf;
1047         struct nand_bbt_descr *td = this->bbt_td;
1048         struct nand_bbt_descr *md = this->bbt_md;
1049 
1050         if (!this->bbt || !td)
1051                 return -EINVAL;
1052 
1053         /* Allocate a temporary buffer for one eraseblock incl. oob */
1054         len = (1 << this->bbt_erase_shift);
1055         len += (len >> this->page_shift) * mtd->oobsize;
1056         buf = kmalloc(len, GFP_KERNEL);
1057         if (!buf)
1058                 return -ENOMEM;
1059 
1060         /* Do we have a bbt per chip? */
1061         if (td->options & NAND_BBT_PERCHIP) {
1062                 chip = (int)(offs >> this->chip_shift);
1063                 chipsel = chip;
1064         } else {
1065                 chip = 0;
1066                 chipsel = -1;
1067         }
1068 
1069         td->version[chip]++;
1070         if (md)
1071                 md->version[chip]++;
1072 
1073         /* Write the bad block table to the device? */
1074         if (td->options & NAND_BBT_WRITE) {
1075                 res = write_bbt(this, buf, td, md, chipsel);
1076                 if (res < 0)
1077                         goto out;
1078         }
1079         /* Write the mirror bad block table to the device? */
1080         if (md && (md->options & NAND_BBT_WRITE)) {
1081                 res = write_bbt(this, buf, md, td, chipsel);
1082         }
1083 
1084  out:
1085         kfree(buf);
1086         return res;
1087 }
1088 
1089 /**
1090  * mark_bbt_regions - [GENERIC] mark the bad block table regions
1091  * @this: the NAND device
1092  * @td: bad block table descriptor
1093  *
1094  * The bad block table regions are marked as "bad" to prevent accidental
1095  * erasures / writes. The regions are identified by the mark 0x02.
1096  */
1097 static void mark_bbt_region(struct nand_chip *this, struct nand_bbt_descr *td)
1098 {
1099         u64 targetsize = nanddev_target_size(&this->base);
1100         struct mtd_info *mtd = nand_to_mtd(this);
1101         int i, j, chips, block, nrblocks, update;
1102         uint8_t oldval;
1103 
1104         /* Do we have a bbt per chip? */
1105         if (td->options & NAND_BBT_PERCHIP) {
1106                 chips = nanddev_ntargets(&this->base);
1107                 nrblocks = (int)(targetsize >> this->bbt_erase_shift);
1108         } else {
1109                 chips = 1;
1110                 nrblocks = (int)(mtd->size >> this->bbt_erase_shift);
1111         }
1112 
1113         for (i = 0; i < chips; i++) {
1114                 if ((td->options & NAND_BBT_ABSPAGE) ||
1115                     !(td->options & NAND_BBT_WRITE)) {
1116                         if (td->pages[i] == -1)
1117                                 continue;
1118                         block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
1119                         oldval = bbt_get_entry(this, block);
1120                         bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
1121                         if ((oldval != BBT_BLOCK_RESERVED) &&
1122                                         td->reserved_block_code)
1123                                 nand_update_bbt(this, (loff_t)block <<
1124                                                 this->bbt_erase_shift);
1125                         continue;
1126                 }
1127                 update = 0;
1128                 if (td->options & NAND_BBT_LASTBLOCK)
1129                         block = ((i + 1) * nrblocks) - td->maxblocks;
1130                 else
1131                         block = i * nrblocks;
1132                 for (j = 0; j < td->maxblocks; j++) {
1133                         oldval = bbt_get_entry(this, block);
1134                         bbt_mark_entry(this, block, BBT_BLOCK_RESERVED);
1135                         if (oldval != BBT_BLOCK_RESERVED)
1136                                 update = 1;
1137                         block++;
1138                 }
1139                 /*
1140                  * If we want reserved blocks to be recorded to flash, and some
1141                  * new ones have been marked, then we need to update the stored
1142                  * bbts.  This should only happen once.
1143                  */
1144                 if (update && td->reserved_block_code)
1145                         nand_update_bbt(this, (loff_t)(block - 1) <<
1146                                         this->bbt_erase_shift);
1147         }
1148 }
1149 
1150 /**
1151  * verify_bbt_descr - verify the bad block description
1152  * @this: the NAND device
1153  * @bd: the table to verify
1154  *
1155  * This functions performs a few sanity checks on the bad block description
1156  * table.
1157  */
1158 static void verify_bbt_descr(struct nand_chip *this, struct nand_bbt_descr *bd)
1159 {
1160         u64 targetsize = nanddev_target_size(&this->base);
1161         struct mtd_info *mtd = nand_to_mtd(this);
1162         u32 pattern_len;
1163         u32 bits;
1164         u32 table_size;
1165 
1166         if (!bd)
1167                 return;
1168 
1169         pattern_len = bd->len;
1170         bits = bd->options & NAND_BBT_NRBITS_MSK;
1171 
1172         BUG_ON((this->bbt_options & NAND_BBT_NO_OOB) &&
1173                         !(this->bbt_options & NAND_BBT_USE_FLASH));
1174         BUG_ON(!bits);
1175 
1176         if (bd->options & NAND_BBT_VERSION)
1177                 pattern_len++;
1178 
1179         if (bd->options & NAND_BBT_NO_OOB) {
1180                 BUG_ON(!(this->bbt_options & NAND_BBT_USE_FLASH));
1181                 BUG_ON(!(this->bbt_options & NAND_BBT_NO_OOB));
1182                 BUG_ON(bd->offs);
1183                 if (bd->options & NAND_BBT_VERSION)
1184                         BUG_ON(bd->veroffs != bd->len);
1185                 BUG_ON(bd->options & NAND_BBT_SAVECONTENT);
1186         }
1187 
1188         if (bd->options & NAND_BBT_PERCHIP)
1189                 table_size = targetsize >> this->bbt_erase_shift;
1190         else
1191                 table_size = mtd->size >> this->bbt_erase_shift;
1192         table_size >>= 3;
1193         table_size *= bits;
1194         if (bd->options & NAND_BBT_NO_OOB)
1195                 table_size += pattern_len;
1196         BUG_ON(table_size > (1 << this->bbt_erase_shift));
1197 }
1198 
1199 /**
1200  * nand_scan_bbt - [NAND Interface] scan, find, read and maybe create bad block table(s)
1201  * @this: the NAND device
1202  * @bd: descriptor for the good/bad block search pattern
1203  *
1204  * The function checks, if a bad block table(s) is/are already available. If
1205  * not it scans the device for manufacturer marked good / bad blocks and writes
1206  * the bad block table(s) to the selected place.
1207  *
1208  * The bad block table memory is allocated here. It must be freed by calling
1209  * the nand_free_bbt function.
1210  */
1211 static int nand_scan_bbt(struct nand_chip *this, struct nand_bbt_descr *bd)
1212 {
1213         struct mtd_info *mtd = nand_to_mtd(this);
1214         int len, res;
1215         uint8_t *buf;
1216         struct nand_bbt_descr *td = this->bbt_td;
1217         struct nand_bbt_descr *md = this->bbt_md;
1218 
1219         len = (mtd->size >> (this->bbt_erase_shift + 2)) ? : 1;
1220         /*
1221          * Allocate memory (2bit per block) and clear the memory bad block
1222          * table.
1223          */
1224         this->bbt = kzalloc(len, GFP_KERNEL);
1225         if (!this->bbt)
1226                 return -ENOMEM;
1227 
1228         /*
1229          * If no primary table decriptor is given, scan the device to build a
1230          * memory based bad block table.
1231          */
1232         if (!td) {
1233                 if ((res = nand_memory_bbt(this, bd))) {
1234                         pr_err("nand_bbt: can't scan flash and build the RAM-based BBT\n");
1235                         goto err_free_bbt;
1236                 }
1237                 return 0;
1238         }
1239         verify_bbt_descr(this, td);
1240         verify_bbt_descr(this, md);
1241 
1242         /* Allocate a temporary buffer for one eraseblock incl. oob */
1243         len = (1 << this->bbt_erase_shift);
1244         len += (len >> this->page_shift) * mtd->oobsize;
1245         buf = vmalloc(len);
1246         if (!buf) {
1247                 res = -ENOMEM;
1248                 goto err_free_bbt;
1249         }
1250 
1251         /* Is the bbt at a given page? */
1252         if (td->options & NAND_BBT_ABSPAGE) {
1253                 read_abs_bbts(this, buf, td, md);
1254         } else {
1255                 /* Search the bad block table using a pattern in oob */
1256                 search_read_bbts(this, buf, td, md);
1257         }
1258 
1259         res = check_create(this, buf, bd);
1260         if (res)
1261                 goto err_free_buf;
1262 
1263         /* Prevent the bbt regions from erasing / writing */
1264         mark_bbt_region(this, td);
1265         if (md)
1266                 mark_bbt_region(this, md);
1267 
1268         vfree(buf);
1269         return 0;
1270 
1271 err_free_buf:
1272         vfree(buf);
1273 err_free_bbt:
1274         kfree(this->bbt);
1275         this->bbt = NULL;
1276         return res;
1277 }
1278 
1279 /*
1280  * Define some generic bad / good block scan pattern which are used
1281  * while scanning a device for factory marked good / bad blocks.
1282  */
1283 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
1284 
1285 /* Generic flash bbt descriptors */
1286 static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
1287 static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };
1288 
1289 static struct nand_bbt_descr bbt_main_descr = {
1290         .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
1291                 | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
1292         .offs = 8,
1293         .len = 4,
1294         .veroffs = 12,
1295         .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
1296         .pattern = bbt_pattern
1297 };
1298 
1299 static struct nand_bbt_descr bbt_mirror_descr = {
1300         .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
1301                 | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
1302         .offs = 8,
1303         .len = 4,
1304         .veroffs = 12,
1305         .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
1306         .pattern = mirror_pattern
1307 };
1308 
1309 static struct nand_bbt_descr bbt_main_no_oob_descr = {
1310         .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
1311                 | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
1312                 | NAND_BBT_NO_OOB,
1313         .len = 4,
1314         .veroffs = 4,
1315         .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
1316         .pattern = bbt_pattern
1317 };
1318 
1319 static struct nand_bbt_descr bbt_mirror_no_oob_descr = {
1320         .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
1321                 | NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP
1322                 | NAND_BBT_NO_OOB,
1323         .len = 4,
1324         .veroffs = 4,
1325         .maxblocks = NAND_BBT_SCAN_MAXBLOCKS,
1326         .pattern = mirror_pattern
1327 };
1328 
1329 #define BADBLOCK_SCAN_MASK (~NAND_BBT_NO_OOB)
1330 /**
1331  * nand_create_badblock_pattern - [INTERN] Creates a BBT descriptor structure
1332  * @this: NAND chip to create descriptor for
1333  *
1334  * This function allocates and initializes a nand_bbt_descr for BBM detection
1335  * based on the properties of @this. The new descriptor is stored in
1336  * this->badblock_pattern. Thus, this->badblock_pattern should be NULL when
1337  * passed to this function.
1338  */
1339 static int nand_create_badblock_pattern(struct nand_chip *this)
1340 {
1341         struct nand_bbt_descr *bd;
1342         if (this->badblock_pattern) {
1343                 pr_warn("Bad block pattern already allocated; not replacing\n");
1344                 return -EINVAL;
1345         }
1346         bd = kzalloc(sizeof(*bd), GFP_KERNEL);
1347         if (!bd)
1348                 return -ENOMEM;
1349         bd->options = this->bbt_options & BADBLOCK_SCAN_MASK;
1350         bd->offs = this->badblockpos;
1351         bd->len = (this->options & NAND_BUSWIDTH_16) ? 2 : 1;
1352         bd->pattern = scan_ff_pattern;
1353         bd->options |= NAND_BBT_DYNAMICSTRUCT;
1354         this->badblock_pattern = bd;
1355         return 0;
1356 }
1357 
1358 /**
1359  * nand_create_bbt - [NAND Interface] Select a default bad block table for the device
1360  * @this: NAND chip object
1361  *
1362  * This function selects the default bad block table support for the device and
1363  * calls the nand_scan_bbt function.
1364  */
1365 int nand_create_bbt(struct nand_chip *this)
1366 {
1367         int ret;
1368 
1369         /* Is a flash based bad block table requested? */
1370         if (this->bbt_options & NAND_BBT_USE_FLASH) {
1371                 /* Use the default pattern descriptors */
1372                 if (!this->bbt_td) {
1373                         if (this->bbt_options & NAND_BBT_NO_OOB) {
1374                                 this->bbt_td = &bbt_main_no_oob_descr;
1375                                 this->bbt_md = &bbt_mirror_no_oob_descr;
1376                         } else {
1377                                 this->bbt_td = &bbt_main_descr;
1378                                 this->bbt_md = &bbt_mirror_descr;
1379                         }
1380                 }
1381         } else {
1382                 this->bbt_td = NULL;
1383                 this->bbt_md = NULL;
1384         }
1385 
1386         if (!this->badblock_pattern) {
1387                 ret = nand_create_badblock_pattern(this);
1388                 if (ret)
1389                         return ret;
1390         }
1391 
1392         return nand_scan_bbt(this, this->badblock_pattern);
1393 }
1394 EXPORT_SYMBOL(nand_create_bbt);
1395 
1396 /**
1397  * nand_isreserved_bbt - [NAND Interface] Check if a block is reserved
1398  * @this: NAND chip object
1399  * @offs: offset in the device
1400  */
1401 int nand_isreserved_bbt(struct nand_chip *this, loff_t offs)
1402 {
1403         int block;
1404 
1405         block = (int)(offs >> this->bbt_erase_shift);
1406         return bbt_get_entry(this, block) == BBT_BLOCK_RESERVED;
1407 }
1408 
1409 /**
1410  * nand_isbad_bbt - [NAND Interface] Check if a block is bad
1411  * @this: NAND chip object
1412  * @offs: offset in the device
1413  * @allowbbt: allow access to bad block table region
1414  */
1415 int nand_isbad_bbt(struct nand_chip *this, loff_t offs, int allowbbt)
1416 {
1417         int block, res;
1418 
1419         block = (int)(offs >> this->bbt_erase_shift);
1420         res = bbt_get_entry(this, block);
1421 
1422         pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
1423                  (unsigned int)offs, block, res);
1424 
1425         switch (res) {
1426         case BBT_BLOCK_GOOD:
1427                 return 0;
1428         case BBT_BLOCK_WORN:
1429                 return 1;
1430         case BBT_BLOCK_RESERVED:
1431                 return allowbbt ? 0 : 1;
1432         }
1433         return 1;
1434 }
1435 
1436 /**
1437  * nand_markbad_bbt - [NAND Interface] Mark a block bad in the BBT
1438  * @this: NAND chip object
1439  * @offs: offset of the bad block
1440  */
1441 int nand_markbad_bbt(struct nand_chip *this, loff_t offs)
1442 {
1443         int block, ret = 0;
1444 
1445         block = (int)(offs >> this->bbt_erase_shift);
1446 
1447         /* Mark bad block in memory */
1448         bbt_mark_entry(this, block, BBT_BLOCK_WORN);
1449 
1450         /* Update flash-based bad block table */
1451         if (this->bbt_options & NAND_BBT_USE_FLASH)
1452                 ret = nand_update_bbt(this, offs);
1453 
1454         return ret;
1455 }