drivers/mtd/nftlcore.c

   1 /* Linux driver for NAND Flash Translation Layer      */
   2 /* (c) 1999 Machine Vision Holdings, Inc.             */
   3 /* Author: David Woodhouse <dwmw2@infradead.org>      */
   4 /* $Id: nftlcore.c,v 1.98 2005/11/07 11:14:21 gleixner Exp $ */
   5
   6 /*
   7   The contents of this file are distributed under the GNU General
   8   Public License version 2. The author places no additional
   9   restrictions of any kind on it.
  10  */
  11
  12 #define PRERELEASE
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <asm/errno.h>
  17 #include <asm/io.h>
  18 #include <asm/uaccess.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/pci.h>
  21 #include <linux/delay.h>
  22 #include <linux/slab.h>
  23 #include <linux/sched.h>
  24 #include <linux/init.h>
  25 #include <linux/hdreg.h>
  26
  27 #include <linux/kmod.h>
  28 #include <linux/mtd/mtd.h>
  29 #include <linux/mtd/nand.h>
  30 #include <linux/mtd/nftl.h>
  31 #include <linux/mtd/blktrans.h>
  32
  33 /* maximum number of loops while examining next block, to have a
  34    chance to detect consistency problems (they should never happen
  35    because of the checks done in the mounting */
  36
  37 #define MAX_LOOPS 10000
  38
  39
  40 static void nftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
  41 {
  42         struct NFTLrecord *nftl;
  43         unsigned long temp;
  44
  45         if (mtd->type != MTD_NANDFLASH)
  46                 return;
  47         /* OK, this is moderately ugly.  But probably safe.  Alternatives? */
  48         if (memcmp(mtd->name, "DiskOnChip", 10))
  49                 return;
  50
  51         if (!mtd->block_isbad) {
  52                 printk(KERN_ERR
  53 "NFTL no longer supports the old DiskOnChip drivers loaded via docprobe.\n"
  54 "Please use the new diskonchip driver under the NAND subsystem.\n");
  55                 return;
  56         }
  57
  58         DEBUG(MTD_DEBUG_LEVEL1, "NFTL: add_mtd for %s\n", mtd->name);
  59
  60         nftl = kmalloc(sizeof(struct NFTLrecord), GFP_KERNEL);
  61
  62         if (!nftl) {
  63                 printk(KERN_WARNING "NFTL: out of memory for data structures\n");
  64                 return;
  65         }
  66         memset(nftl, 0, sizeof(*nftl));
  67
  68         nftl->mbd.mtd = mtd;
  69         nftl->mbd.devnum = -1;
  70         nftl->mbd.blksize = 512;
  71         nftl->mbd.tr = tr;
  72
  73         if (NFTL_mount(nftl) < 0) {
  74                 printk(KERN_WARNING "NFTL: could not mount device\n");
  75                 kfree(nftl);
  76                 return;
  77         }
  78
  79         /* OK, it's a new one. Set up all the data structures. */
  80
  81         /* Calculate geometry */
  82         nftl->cylinders = 1024;
  83         nftl->heads = 16;
  84
  85         temp = nftl->cylinders * nftl->heads;
  86         nftl->sectors = nftl->mbd.size / temp;
  87         if (nftl->mbd.size % temp) {
  88                 nftl->sectors++;
  89                 temp = nftl->cylinders * nftl->sectors;
  90                 nftl->heads = nftl->mbd.size / temp;
  91
  92                 if (nftl->mbd.size % temp) {
  93                         nftl->heads++;
  94                         temp = nftl->heads * nftl->sectors;
  95                         nftl->cylinders = nftl->mbd.size / temp;
  96                 }
  97         }
  98
  99         if (nftl->mbd.size != nftl->heads * nftl->cylinders * nftl->sectors) {
 100                 /*
 101                   Oh no we don't have
 102                    mbd.size == heads * cylinders * sectors
 103                 */
 104                 printk(KERN_WARNING "NFTL: cannot calculate a geometry to "
 105                        "match size of 0x%lx.\n", nftl->mbd.size);
 106                 printk(KERN_WARNING "NFTL: using C:%d H:%d S:%d "
 107                         "(== 0x%lx sects)\n",
 108                         nftl->cylinders, nftl->heads , nftl->sectors,
 109                         (long)nftl->cylinders * (long)nftl->heads *
 110                         (long)nftl->sectors );
 111         }
 112
 113         if (add_mtd_blktrans_dev(&nftl->mbd)) {
 114                 kfree(nftl->ReplUnitTable);
 115                 kfree(nftl->EUNtable);
 116                 kfree(nftl);
 117                 return;
 118         }
 119 #ifdef PSYCHO_DEBUG
 120         printk(KERN_INFO "NFTL: Found new nftl%c\n", nftl->mbd.devnum + 'a');
 121 #endif
 122 }
 123
 124 static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
 125 {
 126         struct NFTLrecord *nftl = (void *)dev;
 127
 128         DEBUG(MTD_DEBUG_LEVEL1, "NFTL: remove_dev (i=%d)\n", dev->devnum);
 129
 130         del_mtd_blktrans_dev(dev);
 131         kfree(nftl->ReplUnitTable);
 132         kfree(nftl->EUNtable);
 133         kfree(nftl);
 134 }
 135
 136 /*
 137  * Read oob data from flash
 138  */
 139 int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 140                   size_t *retlen, uint8_t *buf)
 141 {
 142         struct mtd_oob_ops ops;
 143         int res;
 144
 145         ops.mode = MTD_OOB_PLACE;
 146         ops.ooboffs = offs & (mtd->writesize - 1);
 147         ops.ooblen = len;
 148         ops.oobbuf = buf;
 149         ops.datbuf = NULL;
 150         ops.len = len;
 151
 152         res = mtd->read_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
 153         *retlen = ops.retlen;
 154         return res;
 155 }
 156
 157 /*
 158  * Write oob data to flash
 159  */
 160 int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 161                    size_t *retlen, uint8_t *buf)
 162 {
 163         struct mtd_oob_ops ops;
 164         int res;
 165
 166         ops.mode = MTD_OOB_PLACE;
 167         ops.ooboffs = offs & (mtd->writesize - 1);
 168         ops.ooblen = len;
 169         ops.oobbuf = buf;
 170         ops.datbuf = NULL;
 171         ops.len = len;
 172
 173         res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
 174         *retlen = ops.retlen;
 175         return res;
 176 }
 177
 178 #ifdef CONFIG_NFTL_RW
 179
 180 /*
 181  * Write data and oob to flash
 182  */
 183 static int nftl_write(struct mtd_info *mtd, loff_t offs, size_t len,
 184                       size_t *retlen, uint8_t *buf, uint8_t *oob)
 185 {
 186         struct mtd_oob_ops ops;
 187         int res;
 188
 189         ops.mode = MTD_OOB_PLACE;
 190         ops.ooboffs = offs;
 191         ops.ooblen = mtd->oobsize;
 192         ops.oobbuf = oob;
 193         ops.datbuf = buf;
 194         ops.len = len;
 195
 196         res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
 197         *retlen = ops.retlen;
 198         return res;
 199 }
 200
 201 /* Actual NFTL access routines */
 202 /* NFTL_findfreeblock: Find a free Erase Unit on the NFTL partition. This function is used
 203  *      when the give Virtual Unit Chain
 204  */
 205 static u16 NFTL_findfreeblock(struct NFTLrecord *nftl, int desperate )
 206 {
 207         /* For a given Virtual Unit Chain: find or create a free block and
 208            add it to the chain */
 209         /* We're passed the number of the last EUN in the chain, to save us from
 210            having to look it up again */
 211         u16 pot = nftl->LastFreeEUN;
 212         int silly = nftl->nb_blocks;
 213
 214         /* Normally, we force a fold to happen before we run out of free blocks completely */
 215         if (!desperate && nftl->numfreeEUNs < 2) {
 216                 DEBUG(MTD_DEBUG_LEVEL1, "NFTL_findfreeblock: there are too few free EUNs\n");
 217                 return 0xffff;
 218         }
 219
 220         /* Scan for a free block */
 221         do {
 222                 if (nftl->ReplUnitTable[pot] == BLOCK_FREE) {
 223                         nftl->LastFreeEUN = pot;
 224                         nftl->numfreeEUNs--;
 225                         return pot;
 226                 }
 227
 228                 /* This will probably point to the MediaHdr unit itself,
 229                    right at the beginning of the partition. But that unit
 230                    (and the backup unit too) should have the UCI set
 231                    up so that it's not selected for overwriting */
 232                 if (++pot > nftl->lastEUN)
 233                         pot = le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN);
 234
 235                 if (!silly--) {
 236                         printk("Argh! No free blocks found! LastFreeEUN = %d, "
 237                                "FirstEUN = %d\n", nftl->LastFreeEUN,
 238                                le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN));
 239                         return 0xffff;
 240                 }
 241         } while (pot != nftl->LastFreeEUN);
 242
 243         return 0xffff;
 244 }
 245
 246 static u16 NFTL_foldchain (struct NFTLrecord *nftl, unsigned thisVUC, unsigned pendingblock )
 247 {
 248         struct mtd_info *mtd = nftl->mbd.mtd;
 249         u16 BlockMap[MAX_SECTORS_PER_UNIT];
 250         unsigned char BlockLastState[MAX_SECTORS_PER_UNIT];
 251         unsigned char BlockFreeFound[MAX_SECTORS_PER_UNIT];
 252         unsigned int thisEUN;
 253         int block;
 254         int silly;
 255         unsigned int targetEUN;
 256         struct nftl_oob oob;
 257         int inplace = 1;
 258         size_t retlen;
 259
 260         memset(BlockMap, 0xff, sizeof(BlockMap));
 261         memset(BlockFreeFound, 0, sizeof(BlockFreeFound));
 262
 263         thisEUN = nftl->EUNtable[thisVUC];
 264
 265         if (thisEUN == BLOCK_NIL) {
 266                 printk(KERN_WARNING "Trying to fold non-existent "
 267                        "Virtual Unit Chain %d!\n", thisVUC);
 268                 return BLOCK_NIL;
 269         }
 270
 271         /* Scan to find the Erase Unit which holds the actual data for each
 272            512-byte block within the Chain.
 273         */
 274         silly = MAX_LOOPS;
 275         targetEUN = BLOCK_NIL;
 276         while (thisEUN <= nftl->lastEUN ) {
 277                 unsigned int status, foldmark;
 278
 279                 targetEUN = thisEUN;
 280                 for (block = 0; block < nftl->EraseSize / 512; block ++) {
 281                         nftl_read_oob(mtd, (thisEUN * nftl->EraseSize) +
 282                                       (block * 512), 16 , &retlen,
 283                                       (char *)&oob);
 284                         if (block == 2) {
 285                                 foldmark = oob.u.c.FoldMark | oob.u.c.FoldMark1;
 286                                 if (foldmark == FOLD_MARK_IN_PROGRESS) {
 287                                         DEBUG(MTD_DEBUG_LEVEL1,
 288                                               "Write Inhibited on EUN %d\n", thisEUN);
 289                                         inplace = 0;
 290                                 } else {
 291                                         /* There's no other reason not to do inplace,
 292                                            except ones that come later. So we don't need
 293                                            to preserve inplace */
 294                                         inplace = 1;
 295                                 }
 296                         }
 297                         status = oob.b.Status | oob.b.Status1;
 298                         BlockLastState[block] = status;
 299
 300                         switch(status) {
 301                         case SECTOR_FREE:
 302                                 BlockFreeFound[block] = 1;
 303                                 break;
 304
 305                         case SECTOR_USED:
 306                                 if (!BlockFreeFound[block])
 307                                         BlockMap[block] = thisEUN;
 308                                 else
 309                                         printk(KERN_WARNING
 310                                                "SECTOR_USED found after SECTOR_FREE "
 311                                                "in Virtual Unit Chain %d for block %d\n",
 312                                                thisVUC, block);
 313                                 break;
 314                         case SECTOR_DELETED:
 315                                 if (!BlockFreeFound[block])
 316                                         BlockMap[block] = BLOCK_NIL;
 317                                 else
 318                                         printk(KERN_WARNING
 319                                                "SECTOR_DELETED found after SECTOR_FREE "
 320                                                "in Virtual Unit Chain %d for block %d\n",
 321                                                thisVUC, block);
 322                                 break;
 323
 324                         case SECTOR_IGNORE:
 325                                 break;
 326                         default:
 327                                 printk("Unknown status for block %d in EUN %d: %x\n",
 328                                        block, thisEUN, status);
 329                         }
 330                 }
 331
 332                 if (!silly--) {
 333                         printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%x\n",
 334                                thisVUC);
 335                         return BLOCK_NIL;
 336                 }
 337
 338                 thisEUN = nftl->ReplUnitTable[thisEUN];
 339         }
 340
 341         if (inplace) {
 342                 /* We're being asked to be a fold-in-place. Check
 343                    that all blocks which actually have data associated
 344                    with them (i.e. BlockMap[block] != BLOCK_NIL) are
 345                    either already present or SECTOR_FREE in the target
 346                    block. If not, we're going to have to fold out-of-place
 347                    anyway.
 348                 */
 349                 for (block = 0; block < nftl->EraseSize / 512 ; block++) {
 350                         if (BlockLastState[block] != SECTOR_FREE &&
 351                             BlockMap[block] != BLOCK_NIL &&
 352                             BlockMap[block] != targetEUN) {
 353                                 DEBUG(MTD_DEBUG_LEVEL1, "Setting inplace to 0. VUC %d, "
 354                                       "block %d was %x lastEUN, "
 355                                       "and is in EUN %d (%s) %d\n",
 356                                       thisVUC, block, BlockLastState[block],
 357                                       BlockMap[block],
 358                                       BlockMap[block]== targetEUN ? "==" : "!=",
 359                                       targetEUN);
 360                                 inplace = 0;
 361                                 break;
 362                         }
 363                 }
 364
 365                 if (pendingblock >= (thisVUC * (nftl->EraseSize / 512)) &&
 366                     pendingblock < ((thisVUC + 1)* (nftl->EraseSize / 512)) &&
 367                     BlockLastState[pendingblock - (thisVUC * (nftl->EraseSize / 512))] !=
 368                     SECTOR_FREE) {
 369                         DEBUG(MTD_DEBUG_LEVEL1, "Pending write not free in EUN %d. "
 370                               "Folding out of place.\n", targetEUN);
 371                         inplace = 0;
 372                 }
 373         }
 374
 375         if (!inplace) {
 376                 DEBUG(MTD_DEBUG_LEVEL1, "Cannot fold Virtual Unit Chain %d in place. "
 377                       "Trying out-of-place\n", thisVUC);
 378                 /* We need to find a targetEUN to fold into. */
 379                 targetEUN = NFTL_findfreeblock(nftl, 1);
 380                 if (targetEUN == BLOCK_NIL) {
 381                         /* Ouch. Now we're screwed. We need to do a
 382                            fold-in-place of another chain to make room
 383                            for this one. We need a better way of selecting
 384                            which chain to fold, because makefreeblock will
 385                            only ask us to fold the same one again.
 386                         */
 387                         printk(KERN_WARNING
 388                                "NFTL_findfreeblock(desperate) returns 0xffff.\n");
 389                         return BLOCK_NIL;
 390                 }
 391         } else {
 392                 /* We put a fold mark in the chain we are folding only if we
 393                fold in place to help the mount check code. If we do not fold in
 394                place, it is possible to find the valid chain by selecting the
 395                longer one */
 396                 oob.u.c.FoldMark = oob.u.c.FoldMark1 = cpu_to_le16(FOLD_MARK_IN_PROGRESS);
 397                 oob.u.c.unused = 0xffffffff;
 398                 nftl_write_oob(mtd, (nftl->EraseSize * targetEUN) + 2 * 512 + 8,
 399                                8, &retlen, (char *)&oob.u);
 400         }
 401
 402         /* OK. We now know the location of every block in the Virtual Unit Chain,
 403            and the Erase Unit into which we are supposed to be copying.
 404            Go for it.
 405         */
 406         DEBUG(MTD_DEBUG_LEVEL1,"Folding chain %d into unit %d\n", thisVUC, targetEUN);
 407         for (block = 0; block < nftl->EraseSize / 512 ; block++) {
 408                 unsigned char movebuf[512];
 409                 int ret;
 410
 411                 /* If it's in the target EUN already, or if it's pending write, do nothing */
 412                 if (BlockMap[block] == targetEUN ||
 413                     (pendingblock == (thisVUC * (nftl->EraseSize / 512) + block))) {
 414                         continue;
 415                 }
 416
 417                 /* copy only in non free block (free blocks can only
 418                    happen in case of media errors or deleted blocks) */
 419                 if (BlockMap[block] == BLOCK_NIL)
 420                         continue;
 421
 422                 ret = mtd->read(mtd, (nftl->EraseSize * BlockMap[block]) + (block * 512),
 423                                 512, &retlen, movebuf);
 424                 if (ret < 0 && ret != -EUCLEAN) {
 425                         ret = mtd->read(mtd, (nftl->EraseSize * BlockMap[block])
 426                                         + (block * 512), 512, &retlen,
 427                                         movebuf);
 428                         if (ret != -EIO)
 429                                 printk("Error went away on retry.\n");
 430                 }
 431                 memset(&oob, 0xff, sizeof(struct nftl_oob));
 432                 oob.b.Status = oob.b.Status1 = SECTOR_USED;
 433
 434                 nftl_write(nftl->mbd.mtd, (nftl->EraseSize * targetEUN) +
 435                            (block * 512), 512, &retlen, movebuf, (char *)&oob);
 436         }
 437
 438         /* add the header so that it is now a valid chain */
 439         oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum = cpu_to_le16(thisVUC);
 440         oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum = 0xffff;
 441
 442         nftl_write_oob(mtd, (nftl->EraseSize * targetEUN) + 8,
 443                        8, &retlen, (char *)&oob.u);
 444
 445         /* OK. We've moved the whole lot into the new block. Now we have to free the original blocks. */
 446
 447         /* At this point, we have two different chains for this Virtual Unit, and no way to tell
 448            them apart. If we crash now, we get confused. However, both contain the same data, so we
 449            shouldn't actually lose data in this case. It's just that when we load up on a medium which
 450            has duplicate chains, we need to free one of the chains because it's not necessary any more.
 451         */
 452         thisEUN = nftl->EUNtable[thisVUC];
 453         DEBUG(MTD_DEBUG_LEVEL1,"Want to erase\n");
 454
 455         /* For each block in the old chain (except the targetEUN of course),
 456            free it and make it available for future use */
 457         while (thisEUN <= nftl->lastEUN && thisEUN != targetEUN) {
 458                 unsigned int EUNtmp;
 459
 460                 EUNtmp = nftl->ReplUnitTable[thisEUN];
 461
 462                 if (NFTL_formatblock(nftl, thisEUN) < 0) {
 463                         /* could not erase : mark block as reserved
 464                          */
 465                         nftl->ReplUnitTable[thisEUN] = BLOCK_RESERVED;
 466                 } else {
 467                         /* correctly erased : mark it as free */
 468                         nftl->ReplUnitTable[thisEUN] = BLOCK_FREE;
 469                         nftl->numfreeEUNs++;
 470                 }
 471                 thisEUN = EUNtmp;
 472         }
 473
 474         /* Make this the new start of chain for thisVUC */
 475         nftl->ReplUnitTable[targetEUN] = BLOCK_NIL;
 476         nftl->EUNtable[thisVUC] = targetEUN;
 477
 478         return targetEUN;
 479 }
 480
 481 static u16 NFTL_makefreeblock( struct NFTLrecord *nftl , unsigned pendingblock)
 482 {
 483         /* This is the part that needs some cleverness applied.
 484            For now, I'm doing the minimum applicable to actually
 485            get the thing to work.
 486            Wear-levelling and other clever stuff needs to be implemented
 487            and we also need to do some assessment of the results when
 488            the system loses power half-way through the routine.
 489         */
 490         u16 LongestChain = 0;
 491         u16 ChainLength = 0, thislen;
 492         u16 chain, EUN;
 493
 494         for (chain = 0; chain < le32_to_cpu(nftl->MediaHdr.FormattedSize) / nftl->EraseSize; chain++) {
 495                 EUN = nftl->EUNtable[chain];
 496                 thislen = 0;
 497
 498                 while (EUN <= nftl->lastEUN) {
 499                         thislen++;
 500                         //printk("VUC %d reaches len %d with EUN %d\n", chain, thislen, EUN);
 501                         EUN = nftl->ReplUnitTable[EUN] & 0x7fff;
 502                         if (thislen > 0xff00) {
 503                                 printk("Endless loop in Virtual Chain %d: Unit %x\n",
 504                                        chain, EUN);
 505                         }
 506                         if (thislen > 0xff10) {
 507                                 /* Actually, don't return failure. Just ignore this chain and
 508                                    get on with it. */
 509                                 thislen = 0;
 510                                 break;
 511                         }
 512                 }
 513
 514                 if (thislen > ChainLength) {
 515                         //printk("New longest chain is %d with length %d\n", chain, thislen);
 516                         ChainLength = thislen;
 517                         LongestChain = chain;
 518                 }
 519         }
 520
 521         if (ChainLength < 2) {
 522                 printk(KERN_WARNING "No Virtual Unit Chains available for folding. "
 523                        "Failing request\n");
 524                 return 0xffff;
 525         }
 526
 527         return NFTL_foldchain (nftl, LongestChain, pendingblock);
 528 }
 529
 530 /* NFTL_findwriteunit: Return the unit number into which we can write
 531                        for this block. Make it available if it isn't already
 532 */
 533 static inline u16 NFTL_findwriteunit(struct NFTLrecord *nftl, unsigned block)
 534 {
 535         u16 lastEUN;
 536         u16 thisVUC = block / (nftl->EraseSize / 512);
 537         struct mtd_info *mtd = nftl->mbd.mtd;
 538         unsigned int writeEUN;
 539         unsigned long blockofs = (block * 512) & (nftl->EraseSize -1);
 540         size_t retlen;
 541         int silly, silly2 = 3;
 542         struct nftl_oob oob;
 543
 544         do {
 545                 /* Scan the media to find a unit in the VUC which has
 546                    a free space for the block in question.
 547                 */
 548
 549                 /* This condition catches the 0x[7f]fff cases, as well as
 550                    being a sanity check for past-end-of-media access
 551                 */
 552                 lastEUN = BLOCK_NIL;
 553                 writeEUN = nftl->EUNtable[thisVUC];
 554                 silly = MAX_LOOPS;
 555                 while (writeEUN <= nftl->lastEUN) {
 556                         struct nftl_bci bci;
 557                         size_t retlen;
 558                         unsigned int status;
 559
 560                         lastEUN = writeEUN;
 561
 562                         nftl_read_oob(mtd,
 563                                       (writeEUN * nftl->EraseSize) + blockofs,
 564                                       8, &retlen, (char *)&bci);
 565
 566                         DEBUG(MTD_DEBUG_LEVEL2, "Status of block %d in EUN %d is %x\n",
 567                               block , writeEUN, le16_to_cpu(bci.Status));
 568
 569                         status = bci.Status | bci.Status1;
 570                         switch(status) {
 571                         case SECTOR_FREE:
 572                                 return writeEUN;
 573
 574                         case SECTOR_DELETED:
 575                         case SECTOR_USED:
 576                         case SECTOR_IGNORE:
 577                                 break;
 578                         default:
 579                                 // Invalid block. Don't use it any more. Must implement.
 580                                 break;
 581                         }
 582
 583                         if (!silly--) {
 584                                 printk(KERN_WARNING
 585                                        "Infinite loop in Virtual Unit Chain 0x%x\n",
 586                                        thisVUC);
 587                                 return 0xffff;
 588                         }
 589
 590                         /* Skip to next block in chain */
 591                         writeEUN = nftl->ReplUnitTable[writeEUN];
 592                 }
 593
 594                 /* OK. We didn't find one in the existing chain, or there
 595                    is no existing chain. */
 596
 597                 /* Try to find an already-free block */
 598                 writeEUN = NFTL_findfreeblock(nftl, 0);
 599
 600                 if (writeEUN == BLOCK_NIL) {
 601                         /* That didn't work - there were no free blocks just
 602                            waiting to be picked up. We're going to have to fold
 603                            a chain to make room.
 604                         */
 605
 606                         /* First remember the start of this chain */
 607                         //u16 startEUN = nftl->EUNtable[thisVUC];
 608
 609                         //printk("Write to VirtualUnitChain %d, calling makefreeblock()\n", thisVUC);
 610                         writeEUN = NFTL_makefreeblock(nftl, 0xffff);
 611
 612                         if (writeEUN == BLOCK_NIL) {
 613                                 /* OK, we accept that the above comment is
 614                                    lying - there may have been free blocks
 615                                    last time we called NFTL_findfreeblock(),
 616                                    but they are reserved for when we're
 617                                    desperate. Well, now we're desperate.
 618                                 */
 619                                 DEBUG(MTD_DEBUG_LEVEL1, "Using desperate==1 to find free EUN to accommodate write to VUC %d\n", thisVUC);
 620                                 writeEUN = NFTL_findfreeblock(nftl, 1);
 621                         }
 622                         if (writeEUN == BLOCK_NIL) {
 623                                 /* Ouch. This should never happen - we should
 624                                    always be able to make some room somehow.
 625                                    If we get here, we've allocated more storage
 626                                    space than actual media, or our makefreeblock
 627                                    routine is missing something.
 628                                 */
 629                                 printk(KERN_WARNING "Cannot make free space.\n");
 630                                 return BLOCK_NIL;
 631                         }
 632                         //printk("Restarting scan\n");
 633                         lastEUN = BLOCK_NIL;
 634                         continue;
 635                 }
 636
 637                 /* We've found a free block. Insert it into the chain. */
 638
 639                 if (lastEUN != BLOCK_NIL) {
 640                         thisVUC |= 0x8000; /* It's a replacement block */
 641                 } else {
 642                         /* The first block in a new chain */
 643                         nftl->EUNtable[thisVUC] = writeEUN;
 644                 }
 645
 646                 /* set up the actual EUN we're writing into */
 647                 /* Both in our cache... */
 648                 nftl->ReplUnitTable[writeEUN] = BLOCK_NIL;
 649
 650                 /* ... and on the flash itself */
 651                 nftl_read_oob(mtd, writeEUN * nftl->EraseSize + 8, 8,
 652                               &retlen, (char *)&oob.u);
 653
 654                 oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum = cpu_to_le16(thisVUC);
 655
 656                 nftl_write_oob(mtd, writeEUN * nftl->EraseSize + 8, 8,
 657                                &retlen, (char *)&oob.u);
 658
 659                 /* we link the new block to the chain only after the
 660                    block is ready. It avoids the case where the chain
 661                    could point to a free block */
 662                 if (lastEUN != BLOCK_NIL) {
 663                         /* Both in our cache... */
 664                         nftl->ReplUnitTable[lastEUN] = writeEUN;
 665                         /* ... and on the flash itself */
 666                         nftl_read_oob(mtd, (lastEUN * nftl->EraseSize) + 8,
 667                                       8, &retlen, (char *)&oob.u);
 668
 669                         oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum
 670                                 = cpu_to_le16(writeEUN);
 671
 672                         nftl_write_oob(mtd, (lastEUN * nftl->EraseSize) + 8,
 673                                        8, &retlen, (char *)&oob.u);
 674                 }
 675
 676                 return writeEUN;
 677
 678         } while (silly2--);
 679
 680         printk(KERN_WARNING "Error folding to make room for Virtual Unit Chain 0x%x\n",
 681                thisVUC);
 682         return 0xffff;
 683 }
 684
 685 static int nftl_writeblock(struct mtd_blktrans_dev *mbd, unsigned long block,
 686                            char *buffer)
 687 {
 688         struct NFTLrecord *nftl = (void *)mbd;
 689         u16 writeEUN;
 690         unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
 691         size_t retlen;
 692         struct nftl_oob oob;
 693
 694         writeEUN = NFTL_findwriteunit(nftl, block);
 695
 696         if (writeEUN == BLOCK_NIL) {
 697                 printk(KERN_WARNING
 698                        "NFTL_writeblock(): Cannot find block to write to\n");
 699                 /* If we _still_ haven't got a block to use, we're screwed */
 700                 return 1;
 701         }
 702
 703         memset(&oob, 0xff, sizeof(struct nftl_oob));
 704         oob.b.Status = oob.b.Status1 = SECTOR_USED;
 705
 706         nftl_write(nftl->mbd.mtd, (writeEUN * nftl->EraseSize) + blockofs,
 707                    512, &retlen, (char *)buffer, (char *)&oob);
 708         return 0;
 709 }
 710 #endif /* CONFIG_NFTL_RW */
 711
 712 static int nftl_readblock(struct mtd_blktrans_dev *mbd, unsigned long block,
 713                           char *buffer)
 714 {
 715         struct NFTLrecord *nftl = (void *)mbd;
 716         struct mtd_info *mtd = nftl->mbd.mtd;
 717         u16 lastgoodEUN;
 718         u16 thisEUN = nftl->EUNtable[block / (nftl->EraseSize / 512)];
 719         unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
 720         unsigned int status;
 721         int silly = MAX_LOOPS;
 722         size_t retlen;
 723         struct nftl_bci bci;
 724
 725         lastgoodEUN = BLOCK_NIL;
 726
 727         if (thisEUN != BLOCK_NIL) {
 728                 while (thisEUN < nftl->nb_blocks) {
 729                         if (nftl_read_oob(mtd, (thisEUN * nftl->EraseSize) +
 730                                           blockofs, 8, &retlen,
 731                                           (char *)&bci) < 0)
 732                                 status = SECTOR_IGNORE;
 733                         else
 734                                 status = bci.Status | bci.Status1;
 735
 736                         switch (status) {
 737                         case SECTOR_FREE:
 738                                 /* no modification of a sector should follow a free sector */
 739                                 goto the_end;
 740                         case SECTOR_DELETED:
 741                                 lastgoodEUN = BLOCK_NIL;
 742                                 break;
 743                         case SECTOR_USED:
 744                                 lastgoodEUN = thisEUN;
 745                                 break;
 746                         case SECTOR_IGNORE:
 747                                 break;
 748                         default:
 749                                 printk("Unknown status for block %ld in EUN %d: %x\n",
 750                                        block, thisEUN, status);
 751                                 break;
 752                         }
 753
 754                         if (!silly--) {
 755                                 printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%lx\n",
 756                                        block / (nftl->EraseSize / 512));
 757                                 return 1;
 758                         }
 759                         thisEUN = nftl->ReplUnitTable[thisEUN];
 760                 }
 761         }
 762
 763  the_end:
 764         if (lastgoodEUN == BLOCK_NIL) {
 765                 /* the requested block is not on the media, return all 0x00 */
 766                 memset(buffer, 0, 512);
 767         } else {
 768                 loff_t ptr = (lastgoodEUN * nftl->EraseSize) + blockofs;
 769                 size_t retlen;
 770                 int res = mtd->read(mtd, ptr, 512, &retlen, buffer);
 771
 772                 if (res < 0 && res != -EUCLEAN)
 773                         return -EIO;
 774         }
 775         return 0;
 776 }
 777
 778 static int nftl_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
 779 {
 780         struct NFTLrecord *nftl = (void *)dev;
 781
 782         geo->heads = nftl->heads;
 783         geo->sectors = nftl->sectors;
 784         geo->cylinders = nftl->cylinders;
 785
 786         return 0;
 787 }
 788
 789 /****************************************************************************
 790  *
 791  * Module stuff
 792  *
 793  ****************************************************************************/
 794
 795
 796 static struct mtd_blktrans_ops nftl_tr = {
 797         .name           = "nftl",
 798         .major          = NFTL_MAJOR,
 799         .part_bits      = NFTL_PARTN_BITS,
 800         .getgeo         = nftl_getgeo,
 801         .readsect       = nftl_readblock,
 802 #ifdef CONFIG_NFTL_RW
 803         .writesect      = nftl_writeblock,
 804 #endif
 805         .add_mtd        = nftl_add_mtd,
 806         .remove_dev     = nftl_remove_dev,
 807         .owner          = THIS_MODULE,
 808 };
 809
 810 extern char nftlmountrev[];
 811
 812 static int __init init_nftl(void)
 813 {
 814         printk(KERN_INFO "NFTL driver: nftlcore.c $Revision: 1.98 $, nftlmount.c %s\n", nftlmountrev);
 815
 816         return register_mtd_blktrans(&nftl_tr);
 817 }
 818
 819 static void __exit cleanup_nftl(void)
 820 {
 821         deregister_mtd_blktrans(&nftl_tr);
 822 }
 823
 824 module_init(init_nftl);
 825 module_exit(cleanup_nftl);
 826
 827 MODULE_LICENSE("GPL");
 828 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>, Fabrice Bellard <fabrice.bellard@netgem.com> et al.");
 829 MODULE_DESCRIPTION("Support code for NAND Flash Translation Layer, used on M-Systems DiskOnChip 2000 and Millennium");