drivers/mtd/nftlcore.c

   1 /*
   2  * Linux driver for NAND Flash Translation Layer
   3  *
   4  * Copyright © 1999 Machine Vision Holdings, Inc.
   5  * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #define PRERELEASE
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <asm/errno.h>
  27 #include <asm/io.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/delay.h>
  30 #include <linux/slab.h>
  31 #include <linux/init.h>
  32 #include <linux/hdreg.h>
  33 #include <linux/blkdev.h>
  34
  35 #include <linux/kmod.h>
  36 #include <linux/mtd/mtd.h>
  37 #include <linux/mtd/nand.h>
  38 #include <linux/mtd/nftl.h>
  39 #include <linux/mtd/blktrans.h>
  40
  41 /* maximum number of loops while examining next block, to have a
  42    chance to detect consistency problems (they should never happen
  43    because of the checks done in the mounting */
  44
  45 #define MAX_LOOPS 10000
  46
  47
  48 static void nftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
  49 {
  50         struct NFTLrecord *nftl;
  51         unsigned long temp;
  52
  53         if (!mtd_type_is_nand(mtd) || mtd->size > UINT_MAX)
  54                 return;
  55         /* OK, this is moderately ugly.  But probably safe.  Alternatives? */
  56         if (memcmp(mtd->name, "DiskOnChip", 10))
  57                 return;
  58
  59         pr_debug("NFTL: add_mtd for %s\n", mtd->name);
  60
  61         nftl = kzalloc(sizeof(struct NFTLrecord), GFP_KERNEL);
  62
  63         if (!nftl)
  64                 return;
  65
  66         nftl->mbd.mtd = mtd;
  67         nftl->mbd.devnum = -1;
  68
  69         nftl->mbd.tr = tr;
  70
  71         if (NFTL_mount(nftl) < 0) {
  72                 printk(KERN_WARNING "NFTL: could not mount device\n");
  73                 kfree(nftl);
  74                 return;
  75         }
  76
  77         /* OK, it's a new one. Set up all the data structures. */
  78
  79         /* Calculate geometry */
  80         nftl->cylinders = 1024;
  81         nftl->heads = 16;
  82
  83         temp = nftl->cylinders * nftl->heads;
  84         nftl->sectors = nftl->mbd.size / temp;
  85         if (nftl->mbd.size % temp) {
  86                 nftl->sectors++;
  87                 temp = nftl->cylinders * nftl->sectors;
  88                 nftl->heads = nftl->mbd.size / temp;
  89
  90                 if (nftl->mbd.size % temp) {
  91                         nftl->heads++;
  92                         temp = nftl->heads * nftl->sectors;
  93                         nftl->cylinders = nftl->mbd.size / temp;
  94                 }
  95         }
  96
  97         if (nftl->mbd.size != nftl->heads * nftl->cylinders * nftl->sectors) {
  98                 /*
  99                   Oh no we don't have
 100                    mbd.size == heads * cylinders * sectors
 101                 */
 102                 printk(KERN_WARNING "NFTL: cannot calculate a geometry to "
 103                        "match size of 0x%lx.\n", nftl->mbd.size);
 104                 printk(KERN_WARNING "NFTL: using C:%d H:%d S:%d "
 105                         "(== 0x%lx sects)\n",
 106                         nftl->cylinders, nftl->heads , nftl->sectors,
 107                         (long)nftl->cylinders * (long)nftl->heads *
 108                         (long)nftl->sectors );
 109         }
 110
 111         if (add_mtd_blktrans_dev(&nftl->mbd)) {
 112                 kfree(nftl->ReplUnitTable);
 113                 kfree(nftl->EUNtable);
 114                 kfree(nftl);
 115                 return;
 116         }
 117 #ifdef PSYCHO_DEBUG
 118         printk(KERN_INFO "NFTL: Found new nftl%c\n", nftl->mbd.devnum + 'a');
 119 #endif
 120 }
 121
 122 static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
 123 {
 124         struct NFTLrecord *nftl = (void *)dev;
 125
 126         pr_debug("NFTL: remove_dev (i=%d)\n", dev->devnum);
 127
 128         del_mtd_blktrans_dev(dev);
 129         kfree(nftl->ReplUnitTable);
 130         kfree(nftl->EUNtable);
 131 }
 132
 133 /*
 134  * Read oob data from flash
 135  */
 136 int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 137                   size_t *retlen, uint8_t *buf)
 138 {
 139         loff_t mask = mtd->writesize - 1;
 140         struct mtd_oob_ops ops;
 141         int res;
 142
 143         ops.mode = MTD_OPS_PLACE_OOB;
 144         ops.ooboffs = offs & mask;
 145         ops.ooblen = len;
 146         ops.oobbuf = buf;
 147         ops.datbuf = NULL;
 148
 149         res = mtd_read_oob(mtd, offs & ~mask, &ops);
 150         *retlen = ops.oobretlen;
 151         return res;
 152 }
 153
 154 /*
 155  * Write oob data to flash
 156  */
 157 int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 158                    size_t *retlen, uint8_t *buf)
 159 {
 160         loff_t mask = mtd->writesize - 1;
 161         struct mtd_oob_ops ops;
 162         int res;
 163
 164         ops.mode = MTD_OPS_PLACE_OOB;
 165         ops.ooboffs = offs & mask;
 166         ops.ooblen = len;
 167         ops.oobbuf = buf;
 168         ops.datbuf = NULL;
 169
 170         res = mtd_write_oob(mtd, offs & ~mask, &ops);
 171         *retlen = ops.oobretlen;
 172         return res;
 173 }
 174
 175 #ifdef CONFIG_NFTL_RW
 176
 177 /*
 178  * Write data and oob to flash
 179  */
 180 static int nftl_write(struct mtd_info *mtd, loff_t offs, size_t len,
 181                       size_t *retlen, uint8_t *buf, uint8_t *oob)
 182 {
 183         loff_t mask = mtd->writesize - 1;
 184         struct mtd_oob_ops ops;
 185         int res;
 186
 187         ops.mode = MTD_OPS_PLACE_OOB;
 188         ops.ooboffs = offs & mask;
 189         ops.ooblen = mtd->oobsize;
 190         ops.oobbuf = oob;
 191         ops.datbuf = buf;
 192         ops.len = len;
 193
 194         res = mtd_write_oob(mtd, offs & ~mask, &ops);
 195         *retlen = ops.retlen;
 196         return res;
 197 }
 198
 199 /* Actual NFTL access routines */
 200 /* NFTL_findfreeblock: Find a free Erase Unit on the NFTL partition. This function is used
 201  *      when the give Virtual Unit Chain
 202  */
 203 static u16 NFTL_findfreeblock(struct NFTLrecord *nftl, int desperate )
 204 {
 205         /* For a given Virtual Unit Chain: find or create a free block and
 206            add it to the chain */
 207         /* We're passed the number of the last EUN in the chain, to save us from
 208            having to look it up again */
 209         u16 pot = nftl->LastFreeEUN;
 210         int silly = nftl->nb_blocks;
 211
 212         /* Normally, we force a fold to happen before we run out of free blocks completely */
 213         if (!desperate && nftl->numfreeEUNs < 2) {
 214                 pr_debug("NFTL_findfreeblock: there are too few free EUNs\n");
 215                 return BLOCK_NIL;
 216         }
 217
 218         /* Scan for a free block */
 219         do {
 220                 if (nftl->ReplUnitTable[pot] == BLOCK_FREE) {
 221                         nftl->LastFreeEUN = pot;
 222                         nftl->numfreeEUNs--;
 223                         return pot;
 224                 }
 225
 226                 /* This will probably point to the MediaHdr unit itself,
 227                    right at the beginning of the partition. But that unit
 228                    (and the backup unit too) should have the UCI set
 229                    up so that it's not selected for overwriting */
 230                 if (++pot > nftl->lastEUN)
 231                         pot = le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN);
 232
 233                 if (!silly--) {
 234                         printk("Argh! No free blocks found! LastFreeEUN = %d, "
 235                                "FirstEUN = %d\n", nftl->LastFreeEUN,
 236                                le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN));
 237                         return BLOCK_NIL;
 238                 }
 239         } while (pot != nftl->LastFreeEUN);
 240
 241         return BLOCK_NIL;
 242 }
 243
 244 static u16 NFTL_foldchain (struct NFTLrecord *nftl, unsigned thisVUC, unsigned pendingblock )
 245 {
 246         struct mtd_info *mtd = nftl->mbd.mtd;
 247         u16 BlockMap[MAX_SECTORS_PER_UNIT];
 248         unsigned char BlockLastState[MAX_SECTORS_PER_UNIT];
 249         unsigned char BlockFreeFound[MAX_SECTORS_PER_UNIT];
 250         unsigned int thisEUN;
 251         int block;
 252         int silly;
 253         unsigned int targetEUN;
 254         struct nftl_oob oob;
 255         int inplace = 1;
 256         size_t retlen;
 257
 258         memset(BlockMap, 0xff, sizeof(BlockMap));
 259         memset(BlockFreeFound, 0, sizeof(BlockFreeFound));
 260
 261         thisEUN = nftl->EUNtable[thisVUC];
 262
 263         if (thisEUN == BLOCK_NIL) {
 264                 printk(KERN_WARNING "Trying to fold non-existent "
 265                        "Virtual Unit Chain %d!\n", thisVUC);
 266                 return BLOCK_NIL;
 267         }
 268
 269         /* Scan to find the Erase Unit which holds the actual data for each
 270            512-byte block within the Chain.
 271         */
 272         silly = MAX_LOOPS;
 273         targetEUN = BLOCK_NIL;
 274         while (thisEUN <= nftl->lastEUN ) {
 275                 unsigned int status, foldmark;
 276
 277                 targetEUN = thisEUN;
 278                 for (block = 0; block < nftl->EraseSize / 512; block ++) {
 279                         nftl_read_oob(mtd, (thisEUN * nftl->EraseSize) +
 280                                       (block * 512), 16 , &retlen,
 281                                       (char *)&oob);
 282                         if (block == 2) {
 283                                 foldmark = oob.u.c.FoldMark | oob.u.c.FoldMark1;
 284                                 if (foldmark == FOLD_MARK_IN_PROGRESS) {
 285                                         pr_debug("Write Inhibited on EUN %d\n", thisEUN);
 286                                         inplace = 0;
 287                                 } else {
 288                                         /* There's no other reason not to do inplace,
 289                                            except ones that come later. So we don't need
 290                                            to preserve inplace */
 291                                         inplace = 1;
 292                                 }
 293                         }
 294                         status = oob.b.Status | oob.b.Status1;
 295                         BlockLastState[block] = status;
 296
 297                         switch(status) {
 298                         case SECTOR_FREE:
 299                                 BlockFreeFound[block] = 1;
 300                                 break;
 301
 302                         case SECTOR_USED:
 303                                 if (!BlockFreeFound[block])
 304                                         BlockMap[block] = thisEUN;
 305                                 else
 306                                         printk(KERN_WARNING
 307                                                "SECTOR_USED found after SECTOR_FREE "
 308                                                "in Virtual Unit Chain %d for block %d\n",
 309                                                thisVUC, block);
 310                                 break;
 311                         case SECTOR_DELETED:
 312                                 if (!BlockFreeFound[block])
 313                                         BlockMap[block] = BLOCK_NIL;
 314                                 else
 315                                         printk(KERN_WARNING
 316                                                "SECTOR_DELETED found after SECTOR_FREE "
 317                                                "in Virtual Unit Chain %d for block %d\n",
 318                                                thisVUC, block);
 319                                 break;
 320
 321                         case SECTOR_IGNORE:
 322                                 break;
 323                         default:
 324                                 printk("Unknown status for block %d in EUN %d: %x\n",
 325                                        block, thisEUN, status);
 326                         }
 327                 }
 328
 329                 if (!silly--) {
 330                         printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%x\n",
 331                                thisVUC);
 332                         return BLOCK_NIL;
 333                 }
 334
 335                 thisEUN = nftl->ReplUnitTable[thisEUN];
 336         }
 337
 338         if (inplace) {
 339                 /* We're being asked to be a fold-in-place. Check
 340                    that all blocks which actually have data associated
 341                    with them (i.e. BlockMap[block] != BLOCK_NIL) are
 342                    either already present or SECTOR_FREE in the target
 343                    block. If not, we're going to have to fold out-of-place
 344                    anyway.
 345                 */
 346                 for (block = 0; block < nftl->EraseSize / 512 ; block++) {
 347                         if (BlockLastState[block] != SECTOR_FREE &&
 348                             BlockMap[block] != BLOCK_NIL &&
 349                             BlockMap[block] != targetEUN) {
 350                                 pr_debug("Setting inplace to 0. VUC %d, "
 351                                       "block %d was %x lastEUN, "
 352                                       "and is in EUN %d (%s) %d\n",
 353                                       thisVUC, block, BlockLastState[block],
 354                                       BlockMap[block],
 355                                       BlockMap[block]== targetEUN ? "==" : "!=",
 356                                       targetEUN);
 357                                 inplace = 0;
 358                                 break;
 359                         }
 360                 }
 361
 362                 if (pendingblock >= (thisVUC * (nftl->EraseSize / 512)) &&
 363                     pendingblock < ((thisVUC + 1)* (nftl->EraseSize / 512)) &&
 364                     BlockLastState[pendingblock - (thisVUC * (nftl->EraseSize / 512))] !=
 365                     SECTOR_FREE) {
 366                         pr_debug("Pending write not free in EUN %d. "
 367                               "Folding out of place.\n", targetEUN);
 368                         inplace = 0;
 369                 }
 370         }
 371
 372         if (!inplace) {
 373                 pr_debug("Cannot fold Virtual Unit Chain %d in place. "
 374                       "Trying out-of-place\n", thisVUC);
 375                 /* We need to find a targetEUN to fold into. */
 376                 targetEUN = NFTL_findfreeblock(nftl, 1);
 377                 if (targetEUN == BLOCK_NIL) {
 378                         /* Ouch. Now we're screwed. We need to do a
 379                            fold-in-place of another chain to make room
 380                            for this one. We need a better way of selecting
 381                            which chain to fold, because makefreeblock will
 382                            only ask us to fold the same one again.
 383                         */
 384                         printk(KERN_WARNING
 385                                "NFTL_findfreeblock(desperate) returns 0xffff.\n");
 386                         return BLOCK_NIL;
 387                 }
 388         } else {
 389                 /* We put a fold mark in the chain we are folding only if we
 390                fold in place to help the mount check code. If we do not fold in
 391                place, it is possible to find the valid chain by selecting the
 392                longer one */
 393                 oob.u.c.FoldMark = oob.u.c.FoldMark1 = cpu_to_le16(FOLD_MARK_IN_PROGRESS);
 394                 oob.u.c.unused = 0xffffffff;
 395                 nftl_write_oob(mtd, (nftl->EraseSize * targetEUN) + 2 * 512 + 8,
 396                                8, &retlen, (char *)&oob.u);
 397         }
 398
 399         /* OK. We now know the location of every block in the Virtual Unit Chain,
 400            and the Erase Unit into which we are supposed to be copying.
 401            Go for it.
 402         */
 403         pr_debug("Folding chain %d into unit %d\n", thisVUC, targetEUN);
 404         for (block = 0; block < nftl->EraseSize / 512 ; block++) {
 405                 unsigned char movebuf[512];
 406                 int ret;
 407
 408                 /* If it's in the target EUN already, or if it's pending write, do nothing */
 409                 if (BlockMap[block] == targetEUN ||
 410                     (pendingblock == (thisVUC * (nftl->EraseSize / 512) + block))) {
 411                         continue;
 412                 }
 413
 414                 /* copy only in non free block (free blocks can only
 415                    happen in case of media errors or deleted blocks) */
 416                 if (BlockMap[block] == BLOCK_NIL)
 417                         continue;
 418
 419                 ret = mtd_read(mtd,
 420                                (nftl->EraseSize * BlockMap[block]) + (block * 512),
 421                                512,
 422                                &retlen,
 423                                movebuf);
 424                 if (ret < 0 && !mtd_is_bitflip(ret)) {
 425                         ret = mtd_read(mtd,
 426                                        (nftl->EraseSize * BlockMap[block]) + (block * 512),
 427                                        512,
 428                                        &retlen,
 429                                        movebuf);
 430                         if (ret != -EIO)
 431                                 printk("Error went away on retry.\n");
 432                 }
 433                 memset(&oob, 0xff, sizeof(struct nftl_oob));
 434                 oob.b.Status = oob.b.Status1 = SECTOR_USED;
 435
 436                 nftl_write(nftl->mbd.mtd, (nftl->EraseSize * targetEUN) +
 437                            (block * 512), 512, &retlen, movebuf, (char *)&oob);
 438         }
 439
 440         /* add the header so that it is now a valid chain */
 441         oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum = cpu_to_le16(thisVUC);
 442         oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum = BLOCK_NIL;
 443
 444         nftl_write_oob(mtd, (nftl->EraseSize * targetEUN) + 8,
 445                        8, &retlen, (char *)&oob.u);
 446
 447         /* OK. We've moved the whole lot into the new block. Now we have to free the original blocks. */
 448
 449         /* At this point, we have two different chains for this Virtual Unit, and no way to tell
 450            them apart. If we crash now, we get confused. However, both contain the same data, so we
 451            shouldn't actually lose data in this case. It's just that when we load up on a medium which
 452            has duplicate chains, we need to free one of the chains because it's not necessary any more.
 453         */
 454         thisEUN = nftl->EUNtable[thisVUC];
 455         pr_debug("Want to erase\n");
 456
 457         /* For each block in the old chain (except the targetEUN of course),
 458            free it and make it available for future use */
 459         while (thisEUN <= nftl->lastEUN && thisEUN != targetEUN) {
 460                 unsigned int EUNtmp;
 461
 462                 EUNtmp = nftl->ReplUnitTable[thisEUN];
 463
 464                 if (NFTL_formatblock(nftl, thisEUN) < 0) {
 465                         /* could not erase : mark block as reserved
 466                          */
 467                         nftl->ReplUnitTable[thisEUN] = BLOCK_RESERVED;
 468                 } else {
 469                         /* correctly erased : mark it as free */
 470                         nftl->ReplUnitTable[thisEUN] = BLOCK_FREE;
 471                         nftl->numfreeEUNs++;
 472                 }
 473                 thisEUN = EUNtmp;
 474         }
 475
 476         /* Make this the new start of chain for thisVUC */
 477         nftl->ReplUnitTable[targetEUN] = BLOCK_NIL;
 478         nftl->EUNtable[thisVUC] = targetEUN;
 479
 480         return targetEUN;
 481 }
 482
 483 static u16 NFTL_makefreeblock( struct NFTLrecord *nftl , unsigned pendingblock)
 484 {
 485         /* This is the part that needs some cleverness applied.
 486            For now, I'm doing the minimum applicable to actually
 487            get the thing to work.
 488            Wear-levelling and other clever stuff needs to be implemented
 489            and we also need to do some assessment of the results when
 490            the system loses power half-way through the routine.
 491         */
 492         u16 LongestChain = 0;
 493         u16 ChainLength = 0, thislen;
 494         u16 chain, EUN;
 495
 496         for (chain = 0; chain < le32_to_cpu(nftl->MediaHdr.FormattedSize) / nftl->EraseSize; chain++) {
 497                 EUN = nftl->EUNtable[chain];
 498                 thislen = 0;
 499
 500                 while (EUN <= nftl->lastEUN) {
 501                         thislen++;
 502                         //printk("VUC %d reaches len %d with EUN %d\n", chain, thislen, EUN);
 503                         EUN = nftl->ReplUnitTable[EUN] & 0x7fff;
 504                         if (thislen > 0xff00) {
 505                                 printk("Endless loop in Virtual Chain %d: Unit %x\n",
 506                                        chain, EUN);
 507                         }
 508                         if (thislen > 0xff10) {
 509                                 /* Actually, don't return failure. Just ignore this chain and
 510                                    get on with it. */
 511                                 thislen = 0;
 512                                 break;
 513                         }
 514                 }
 515
 516                 if (thislen > ChainLength) {
 517                         //printk("New longest chain is %d with length %d\n", chain, thislen);
 518                         ChainLength = thislen;
 519                         LongestChain = chain;
 520                 }
 521         }
 522
 523         if (ChainLength < 2) {
 524                 printk(KERN_WARNING "No Virtual Unit Chains available for folding. "
 525                        "Failing request\n");
 526                 return BLOCK_NIL;
 527         }
 528
 529         return NFTL_foldchain (nftl, LongestChain, pendingblock);
 530 }
 531
 532 /* NFTL_findwriteunit: Return the unit number into which we can write
 533                        for this block. Make it available if it isn't already
 534 */
 535 static inline u16 NFTL_findwriteunit(struct NFTLrecord *nftl, unsigned block)
 536 {
 537         u16 lastEUN;
 538         u16 thisVUC = block / (nftl->EraseSize / 512);
 539         struct mtd_info *mtd = nftl->mbd.mtd;
 540         unsigned int writeEUN;
 541         unsigned long blockofs = (block * 512) & (nftl->EraseSize -1);
 542         size_t retlen;
 543         int silly, silly2 = 3;
 544         struct nftl_oob oob;
 545
 546         do {
 547                 /* Scan the media to find a unit in the VUC which has
 548                    a free space for the block in question.
 549                 */
 550
 551                 /* This condition catches the 0x[7f]fff cases, as well as
 552                    being a sanity check for past-end-of-media access
 553                 */
 554                 lastEUN = BLOCK_NIL;
 555                 writeEUN = nftl->EUNtable[thisVUC];
 556                 silly = MAX_LOOPS;
 557                 while (writeEUN <= nftl->lastEUN) {
 558                         struct nftl_bci bci;
 559                         size_t retlen;
 560                         unsigned int status;
 561
 562                         lastEUN = writeEUN;
 563
 564                         nftl_read_oob(mtd,
 565                                       (writeEUN * nftl->EraseSize) + blockofs,
 566                                       8, &retlen, (char *)&bci);
 567
 568                         pr_debug("Status of block %d in EUN %d is %x\n",
 569                               block , writeEUN, le16_to_cpu(bci.Status));
 570
 571                         status = bci.Status | bci.Status1;
 572                         switch(status) {
 573                         case SECTOR_FREE:
 574                                 return writeEUN;
 575
 576                         case SECTOR_DELETED:
 577                         case SECTOR_USED:
 578                         case SECTOR_IGNORE:
 579                                 break;
 580                         default:
 581                                 // Invalid block. Don't use it any more. Must implement.
 582                                 break;
 583                         }
 584
 585                         if (!silly--) {
 586                                 printk(KERN_WARNING
 587                                        "Infinite loop in Virtual Unit Chain 0x%x\n",
 588                                        thisVUC);
 589                                 return BLOCK_NIL;
 590                         }
 591
 592                         /* Skip to next block in chain */
 593                         writeEUN = nftl->ReplUnitTable[writeEUN];
 594                 }
 595
 596                 /* OK. We didn't find one in the existing chain, or there
 597                    is no existing chain. */
 598
 599                 /* Try to find an already-free block */
 600                 writeEUN = NFTL_findfreeblock(nftl, 0);
 601
 602                 if (writeEUN == BLOCK_NIL) {
 603                         /* That didn't work - there were no free blocks just
 604                            waiting to be picked up. We're going to have to fold
 605                            a chain to make room.
 606                         */
 607
 608                         /* First remember the start of this chain */
 609                         //u16 startEUN = nftl->EUNtable[thisVUC];
 610
 611                         //printk("Write to VirtualUnitChain %d, calling makefreeblock()\n", thisVUC);
 612                         writeEUN = NFTL_makefreeblock(nftl, BLOCK_NIL);
 613
 614                         if (writeEUN == BLOCK_NIL) {
 615                                 /* OK, we accept that the above comment is
 616                                    lying - there may have been free blocks
 617                                    last time we called NFTL_findfreeblock(),
 618                                    but they are reserved for when we're
 619                                    desperate. Well, now we're desperate.
 620                                 */
 621                                 pr_debug("Using desperate==1 to find free EUN to accommodate write to VUC %d\n", thisVUC);
 622                                 writeEUN = NFTL_findfreeblock(nftl, 1);
 623                         }
 624                         if (writeEUN == BLOCK_NIL) {
 625                                 /* Ouch. This should never happen - we should
 626                                    always be able to make some room somehow.
 627                                    If we get here, we've allocated more storage
 628                                    space than actual media, or our makefreeblock
 629                                    routine is missing something.
 630                                 */
 631                                 printk(KERN_WARNING "Cannot make free space.\n");
 632                                 return BLOCK_NIL;
 633                         }
 634                         //printk("Restarting scan\n");
 635                         lastEUN = BLOCK_NIL;
 636                         continue;
 637                 }
 638
 639                 /* We've found a free block. Insert it into the chain. */
 640
 641                 if (lastEUN != BLOCK_NIL) {
 642                         thisVUC |= 0x8000; /* It's a replacement block */
 643                 } else {
 644                         /* The first block in a new chain */
 645                         nftl->EUNtable[thisVUC] = writeEUN;
 646                 }
 647
 648                 /* set up the actual EUN we're writing into */
 649                 /* Both in our cache... */
 650                 nftl->ReplUnitTable[writeEUN] = BLOCK_NIL;
 651
 652                 /* ... and on the flash itself */
 653                 nftl_read_oob(mtd, writeEUN * nftl->EraseSize + 8, 8,
 654                               &retlen, (char *)&oob.u);
 655
 656                 oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum = cpu_to_le16(thisVUC);
 657
 658                 nftl_write_oob(mtd, writeEUN * nftl->EraseSize + 8, 8,
 659                                &retlen, (char *)&oob.u);
 660
 661                 /* we link the new block to the chain only after the
 662                    block is ready. It avoids the case where the chain
 663                    could point to a free block */
 664                 if (lastEUN != BLOCK_NIL) {
 665                         /* Both in our cache... */
 666                         nftl->ReplUnitTable[lastEUN] = writeEUN;
 667                         /* ... and on the flash itself */
 668                         nftl_read_oob(mtd, (lastEUN * nftl->EraseSize) + 8,
 669                                       8, &retlen, (char *)&oob.u);
 670
 671                         oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum
 672                                 = cpu_to_le16(writeEUN);
 673
 674                         nftl_write_oob(mtd, (lastEUN * nftl->EraseSize) + 8,
 675                                        8, &retlen, (char *)&oob.u);
 676                 }
 677
 678                 return writeEUN;
 679
 680         } while (silly2--);
 681
 682         printk(KERN_WARNING "Error folding to make room for Virtual Unit Chain 0x%x\n",
 683                thisVUC);
 684         return BLOCK_NIL;
 685 }
 686
 687 static int nftl_writeblock(struct mtd_blktrans_dev *mbd, unsigned long block,
 688                            char *buffer)
 689 {
 690         struct NFTLrecord *nftl = (void *)mbd;
 691         u16 writeEUN;
 692         unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
 693         size_t retlen;
 694         struct nftl_oob oob;
 695
 696         writeEUN = NFTL_findwriteunit(nftl, block);
 697
 698         if (writeEUN == BLOCK_NIL) {
 699                 printk(KERN_WARNING
 700                        "NFTL_writeblock(): Cannot find block to write to\n");
 701                 /* If we _still_ haven't got a block to use, we're screwed */
 702                 return 1;
 703         }
 704
 705         memset(&oob, 0xff, sizeof(struct nftl_oob));
 706         oob.b.Status = oob.b.Status1 = SECTOR_USED;
 707
 708         nftl_write(nftl->mbd.mtd, (writeEUN * nftl->EraseSize) + blockofs,
 709                    512, &retlen, (char *)buffer, (char *)&oob);
 710         return 0;
 711 }
 712 #endif /* CONFIG_NFTL_RW */
 713
 714 static int nftl_readblock(struct mtd_blktrans_dev *mbd, unsigned long block,
 715                           char *buffer)
 716 {
 717         struct NFTLrecord *nftl = (void *)mbd;
 718         struct mtd_info *mtd = nftl->mbd.mtd;
 719         u16 lastgoodEUN;
 720         u16 thisEUN = nftl->EUNtable[block / (nftl->EraseSize / 512)];
 721         unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
 722         unsigned int status;
 723         int silly = MAX_LOOPS;
 724         size_t retlen;
 725         struct nftl_bci bci;
 726
 727         lastgoodEUN = BLOCK_NIL;
 728
 729         if (thisEUN != BLOCK_NIL) {
 730                 while (thisEUN < nftl->nb_blocks) {
 731                         if (nftl_read_oob(mtd, (thisEUN * nftl->EraseSize) +
 732                                           blockofs, 8, &retlen,
 733                                           (char *)&bci) < 0)
 734                                 status = SECTOR_IGNORE;
 735                         else
 736                                 status = bci.Status | bci.Status1;
 737
 738                         switch (status) {
 739                         case SECTOR_FREE:
 740                                 /* no modification of a sector should follow a free sector */
 741                                 goto the_end;
 742                         case SECTOR_DELETED:
 743                                 lastgoodEUN = BLOCK_NIL;
 744                                 break;
 745                         case SECTOR_USED:
 746                                 lastgoodEUN = thisEUN;
 747                                 break;
 748                         case SECTOR_IGNORE:
 749                                 break;
 750                         default:
 751                                 printk("Unknown status for block %ld in EUN %d: %x\n",
 752                                        block, thisEUN, status);
 753                                 break;
 754                         }
 755
 756                         if (!silly--) {
 757                                 printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%lx\n",
 758                                        block / (nftl->EraseSize / 512));
 759                                 return 1;
 760                         }
 761                         thisEUN = nftl->ReplUnitTable[thisEUN];
 762                 }
 763         }
 764
 765  the_end:
 766         if (lastgoodEUN == BLOCK_NIL) {
 767                 /* the requested block is not on the media, return all 0x00 */
 768                 memset(buffer, 0, 512);
 769         } else {
 770                 loff_t ptr = (lastgoodEUN * nftl->EraseSize) + blockofs;
 771                 size_t retlen;
 772                 int res = mtd_read(mtd, ptr, 512, &retlen, buffer);
 773
 774                 if (res < 0 && !mtd_is_bitflip(res))
 775                         return -EIO;
 776         }
 777         return 0;
 778 }
 779
 780 static int nftl_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
 781 {
 782         struct NFTLrecord *nftl = (void *)dev;
 783
 784         geo->heads = nftl->heads;
 785         geo->sectors = nftl->sectors;
 786         geo->cylinders = nftl->cylinders;
 787
 788         return 0;
 789 }
 790
 791 /****************************************************************************
 792  *
 793  * Module stuff
 794  *
 795  ****************************************************************************/
 796
 797
 798 static struct mtd_blktrans_ops nftl_tr = {
 799         .name           = "nftl",
 800         .major          = NFTL_MAJOR,
 801         .part_bits      = NFTL_PARTN_BITS,
 802         .blksize        = 512,
 803         .getgeo         = nftl_getgeo,
 804         .readsect       = nftl_readblock,
 805 #ifdef CONFIG_NFTL_RW
 806         .writesect      = nftl_writeblock,
 807 #endif
 808         .add_mtd        = nftl_add_mtd,
 809         .remove_dev     = nftl_remove_dev,
 810         .owner          = THIS_MODULE,
 811 };
 812
 813 static int __init init_nftl(void)
 814 {
 815         return register_mtd_blktrans(&nftl_tr);
 816 }
 817
 818 static void __exit cleanup_nftl(void)
 819 {
 820         deregister_mtd_blktrans(&nftl_tr);
 821 }
 822
 823 module_init(init_nftl);
 824 module_exit(cleanup_nftl);
 825
 826 MODULE_LICENSE("GPL");
 827 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>, Fabrice Bellard <fabrice.bellard@netgem.com> et al.");
 828 MODULE_DESCRIPTION("Support code for NAND Flash Translation Layer, used on M-Systems DiskOnChip 2000 and Millennium");
 829 MODULE_ALIAS_BLOCKDEV_MAJOR(NFTL_MAJOR);