drivers/mtd/mtdconcat.c

   1 /*
   2  * MTD device concatenation layer
   3  *
   4  * (C) 2002 Robert Kaiser <rkaiser@sysgo.de>
   5  *
   6  * NAND support by Christian Gan <cgan@iders.ca>
   7  *
   8  * This code is GPL
   9  *
  10  * $Id: mtdconcat.c,v 1.11 2005/11/07 11:14:20 gleixner Exp $
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17 #include <linux/types.h>
  18
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/mtd/concat.h>
  21
  22 #include <asm/div64.h>
  23
  24 /*
  25  * Our storage structure:
  26  * Subdev points to an array of pointers to struct mtd_info objects
  27  * which is allocated along with this structure
  28  *
  29  */
  30 struct mtd_concat {
  31         struct mtd_info mtd;
  32         int num_subdev;
  33         struct mtd_info **subdev;
  34 };
  35
  36 /*
  37  * how to calculate the size required for the above structure,
  38  * including the pointer array subdev points to:
  39  */
  40 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  41         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  42
  43 /*
  44  * Given a pointer to the MTD object in the mtd_concat structure,
  45  * we can retrieve the pointer to that structure with this macro.
  46  */
  47 #define CONCAT(x)  ((struct mtd_concat *)(x))
  48
  49 /*
  50  * MTD methods which look up the relevant subdevice, translate the
  51  * effective address and pass through to the subdevice.
  52  */
  53
  54 static int
  55 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  56             size_t * retlen, u_char * buf)
  57 {
  58         struct mtd_concat *concat = CONCAT(mtd);
  59         int ret = 0, err;
  60         int i;
  61
  62         *retlen = 0;
  63
  64         for (i = 0; i < concat->num_subdev; i++) {
  65                 struct mtd_info *subdev = concat->subdev[i];
  66                 size_t size, retsize;
  67
  68                 if (from >= subdev->size) {
  69                         /* Not destined for this subdev */
  70                         size = 0;
  71                         from -= subdev->size;
  72                         continue;
  73                 }
  74                 if (from + len > subdev->size)
  75                         /* First part goes into this subdev */
  76                         size = subdev->size - from;
  77                 else
  78                         /* Entire transaction goes into this subdev */
  79                         size = len;
  80
  81                 err = subdev->read(subdev, from, size, &retsize, buf);
  82
  83                 /* Save information about bitflips! */
  84                 if (unlikely(err)) {
  85                         if (err == -EBADMSG) {
  86                                 mtd->ecc_stats.failed++;
  87                                 ret = err;
  88                         } else if (err == -EUCLEAN) {
  89                                 mtd->ecc_stats.corrected++;
  90                                 /* Do not overwrite -EBADMSG !! */
  91                                 if (!ret)
  92                                         ret = err;
  93                         } else
  94                                 return err;
  95                 }
  96
  97                 *retlen += retsize;
  98                 len -= size;
  99                 if (len == 0)
 100                         return ret;
 101
 102                 buf += size;
 103                 from = 0;
 104         }
 105         return -EINVAL;
 106 }
 107
 108 static int
 109 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 110              size_t * retlen, const u_char * buf)
 111 {
 112         struct mtd_concat *concat = CONCAT(mtd);
 113         int err = -EINVAL;
 114         int i;
 115
 116         if (!(mtd->flags & MTD_WRITEABLE))
 117                 return -EROFS;
 118
 119         *retlen = 0;
 120
 121         for (i = 0; i < concat->num_subdev; i++) {
 122                 struct mtd_info *subdev = concat->subdev[i];
 123                 size_t size, retsize;
 124
 125                 if (to >= subdev->size) {
 126                         size = 0;
 127                         to -= subdev->size;
 128                         continue;
 129                 }
 130                 if (to + len > subdev->size)
 131                         size = subdev->size - to;
 132                 else
 133                         size = len;
 134
 135                 if (!(subdev->flags & MTD_WRITEABLE))
 136                         err = -EROFS;
 137                 else
 138                         err = subdev->write(subdev, to, size, &retsize, buf);
 139
 140                 if (err)
 141                         break;
 142
 143                 *retlen += retsize;
 144                 len -= size;
 145                 if (len == 0)
 146                         break;
 147
 148                 err = -EINVAL;
 149                 buf += size;
 150                 to = 0;
 151         }
 152         return err;
 153 }
 154
 155 static int
 156 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 157                 unsigned long count, loff_t to, size_t * retlen)
 158 {
 159         struct mtd_concat *concat = CONCAT(mtd);
 160         struct kvec *vecs_copy;
 161         unsigned long entry_low, entry_high;
 162         size_t total_len = 0;
 163         int i;
 164         int err = -EINVAL;
 165
 166         if (!(mtd->flags & MTD_WRITEABLE))
 167                 return -EROFS;
 168
 169         *retlen = 0;
 170
 171         /* Calculate total length of data */
 172         for (i = 0; i < count; i++)
 173                 total_len += vecs[i].iov_len;
 174
 175         /* Do not allow write past end of device */
 176         if ((to + total_len) > mtd->size)
 177                 return -EINVAL;
 178
 179         /* Check alignment */
 180         if (mtd->writesize > 1) {
 181                 loff_t __to = to;
 182                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
 183                         return -EINVAL;
 184         }
 185
 186         /* make a copy of vecs */
 187         vecs_copy = kmalloc(sizeof(struct kvec) * count, GFP_KERNEL);
 188         if (!vecs_copy)
 189                 return -ENOMEM;
 190         memcpy(vecs_copy, vecs, sizeof(struct kvec) * count);
 191
 192         entry_low = 0;
 193         for (i = 0; i < concat->num_subdev; i++) {
 194                 struct mtd_info *subdev = concat->subdev[i];
 195                 size_t size, wsize, retsize, old_iov_len;
 196
 197                 if (to >= subdev->size) {
 198                         to -= subdev->size;
 199                         continue;
 200                 }
 201
 202                 size = min(total_len, (size_t)(subdev->size - to));
 203                 wsize = size; /* store for future use */
 204
 205                 entry_high = entry_low;
 206                 while (entry_high < count) {
 207                         if (size <= vecs_copy[entry_high].iov_len)
 208                                 break;
 209                         size -= vecs_copy[entry_high++].iov_len;
 210                 }
 211
 212                 old_iov_len = vecs_copy[entry_high].iov_len;
 213                 vecs_copy[entry_high].iov_len = size;
 214
 215                 if (!(subdev->flags & MTD_WRITEABLE))
 216                         err = -EROFS;
 217                 else
 218                         err = subdev->writev(subdev, &vecs_copy[entry_low],
 219                                 entry_high - entry_low + 1, to, &retsize);
 220
 221                 vecs_copy[entry_high].iov_len = old_iov_len - size;
 222                 vecs_copy[entry_high].iov_base += size;
 223
 224                 entry_low = entry_high;
 225
 226                 if (err)
 227                         break;
 228
 229                 *retlen += retsize;
 230                 total_len -= wsize;
 231
 232                 if (total_len == 0)
 233                         break;
 234
 235                 err = -EINVAL;
 236                 to = 0;
 237         }
 238
 239         kfree(vecs_copy);
 240         return err;
 241 }
 242
 243 static int
 244 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 245 {
 246         struct mtd_concat *concat = CONCAT(mtd);
 247         struct mtd_oob_ops devops = *ops;
 248         int i, err, ret = 0;
 249
 250         ops->retlen = 0;
 251
 252         for (i = 0; i < concat->num_subdev; i++) {
 253                 struct mtd_info *subdev = concat->subdev[i];
 254
 255                 if (from >= subdev->size) {
 256                         from -= subdev->size;
 257                         continue;
 258                 }
 259
 260                 /* partial read ? */
 261                 if (from + devops.len > subdev->size)
 262                         devops.len = subdev->size - from;
 263
 264                 err = subdev->read_oob(subdev, from, &devops);
 265                 ops->retlen += devops.retlen;
 266
 267                 /* Save information about bitflips! */
 268                 if (unlikely(err)) {
 269                         if (err == -EBADMSG) {
 270                                 mtd->ecc_stats.failed++;
 271                                 ret = err;
 272                         } else if (err == -EUCLEAN) {
 273                                 mtd->ecc_stats.corrected++;
 274                                 /* Do not overwrite -EBADMSG !! */
 275                                 if (!ret)
 276                                         ret = err;
 277                         } else
 278                                 return err;
 279                 }
 280
 281                 devops.len = ops->len - ops->retlen;
 282                 if (!devops.len)
 283                         return ret;
 284
 285                 if (devops.datbuf)
 286                         devops.datbuf += devops.retlen;
 287                 if (devops.oobbuf)
 288                         devops.oobbuf += devops.ooblen;
 289
 290                 from = 0;
 291         }
 292         return -EINVAL;
 293 }
 294
 295 static int
 296 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 297 {
 298         struct mtd_concat *concat = CONCAT(mtd);
 299         struct mtd_oob_ops devops = *ops;
 300         int i, err;
 301
 302         if (!(mtd->flags & MTD_WRITEABLE))
 303                 return -EROFS;
 304
 305         ops->retlen = 0;
 306
 307         for (i = 0; i < concat->num_subdev; i++) {
 308                 struct mtd_info *subdev = concat->subdev[i];
 309
 310                 if (to >= subdev->size) {
 311                         to -= subdev->size;
 312                         continue;
 313                 }
 314
 315                 /* partial write ? */
 316                 if (to + devops.len > subdev->size)
 317                         devops.len = subdev->size - to;
 318
 319                 err = subdev->write_oob(subdev, to, &devops);
 320                 ops->retlen += devops.retlen;
 321                 if (err)
 322                         return err;
 323
 324                 devops.len = ops->len - ops->retlen;
 325                 if (!devops.len)
 326                         return 0;
 327
 328                 if (devops.datbuf)
 329                         devops.datbuf += devops.retlen;
 330                 if (devops.oobbuf)
 331                         devops.oobbuf += devops.ooblen;
 332                 to = 0;
 333         }
 334         return -EINVAL;
 335 }
 336
 337 static void concat_erase_callback(struct erase_info *instr)
 338 {
 339         wake_up((wait_queue_head_t *) instr->priv);
 340 }
 341
 342 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 343 {
 344         int err;
 345         wait_queue_head_t waitq;
 346         DECLARE_WAITQUEUE(wait, current);
 347
 348         /*
 349          * This code was stol^H^H^H^Hinspired by mtdchar.c
 350          */
 351         init_waitqueue_head(&waitq);
 352
 353         erase->mtd = mtd;
 354         erase->callback = concat_erase_callback;
 355         erase->priv = (unsigned long) &waitq;
 356
 357         /*
 358          * FIXME: Allow INTERRUPTIBLE. Which means
 359          * not having the wait_queue head on the stack.
 360          */
 361         err = mtd->erase(mtd, erase);
 362         if (!err) {
 363                 set_current_state(TASK_UNINTERRUPTIBLE);
 364                 add_wait_queue(&waitq, &wait);
 365                 if (erase->state != MTD_ERASE_DONE
 366                     && erase->state != MTD_ERASE_FAILED)
 367                         schedule();
 368                 remove_wait_queue(&waitq, &wait);
 369                 set_current_state(TASK_RUNNING);
 370
 371                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 372         }
 373         return err;
 374 }
 375
 376 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 377 {
 378         struct mtd_concat *concat = CONCAT(mtd);
 379         struct mtd_info *subdev;
 380         int i, err;
 381         u_int32_t length, offset = 0;
 382         struct erase_info *erase;
 383
 384         if (!(mtd->flags & MTD_WRITEABLE))
 385                 return -EROFS;
 386
 387         if (instr->addr > concat->mtd.size)
 388                 return -EINVAL;
 389
 390         if (instr->len + instr->addr > concat->mtd.size)
 391                 return -EINVAL;
 392
 393         /*
 394          * Check for proper erase block alignment of the to-be-erased area.
 395          * It is easier to do this based on the super device's erase
 396          * region info rather than looking at each particular sub-device
 397          * in turn.
 398          */
 399         if (!concat->mtd.numeraseregions) {
 400                 /* the easy case: device has uniform erase block size */
 401                 if (instr->addr & (concat->mtd.erasesize - 1))
 402                         return -EINVAL;
 403                 if (instr->len & (concat->mtd.erasesize - 1))
 404                         return -EINVAL;
 405         } else {
 406                 /* device has variable erase size */
 407                 struct mtd_erase_region_info *erase_regions =
 408                     concat->mtd.eraseregions;
 409
 410                 /*
 411                  * Find the erase region where the to-be-erased area begins:
 412                  */
 413                 for (i = 0; i < concat->mtd.numeraseregions &&
 414                      instr->addr >= erase_regions[i].offset; i++) ;
 415                 --i;
 416
 417                 /*
 418                  * Now erase_regions[i] is the region in which the
 419                  * to-be-erased area begins. Verify that the starting
 420                  * offset is aligned to this region's erase size:
 421                  */
 422                 if (instr->addr & (erase_regions[i].erasesize - 1))
 423                         return -EINVAL;
 424
 425                 /*
 426                  * now find the erase region where the to-be-erased area ends:
 427                  */
 428                 for (; i < concat->mtd.numeraseregions &&
 429                      (instr->addr + instr->len) >= erase_regions[i].offset;
 430                      ++i) ;
 431                 --i;
 432                 /*
 433                  * check if the ending offset is aligned to this region's erase size
 434                  */
 435                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 436                                                   1))
 437                         return -EINVAL;
 438         }
 439
 440         instr->fail_addr = 0xffffffff;
 441
 442         /* make a local copy of instr to avoid modifying the caller's struct */
 443         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 444
 445         if (!erase)
 446                 return -ENOMEM;
 447
 448         *erase = *instr;
 449         length = instr->len;
 450
 451         /*
 452          * find the subdevice where the to-be-erased area begins, adjust
 453          * starting offset to be relative to the subdevice start
 454          */
 455         for (i = 0; i < concat->num_subdev; i++) {
 456                 subdev = concat->subdev[i];
 457                 if (subdev->size <= erase->addr) {
 458                         erase->addr -= subdev->size;
 459                         offset += subdev->size;
 460                 } else {
 461                         break;
 462                 }
 463         }
 464
 465         /* must never happen since size limit has been verified above */
 466         BUG_ON(i >= concat->num_subdev);
 467
 468         /* now do the erase: */
 469         err = 0;
 470         for (; length > 0; i++) {
 471                 /* loop for all subdevices affected by this request */
 472                 subdev = concat->subdev[i];     /* get current subdevice */
 473
 474                 /* limit length to subdevice's size: */
 475                 if (erase->addr + length > subdev->size)
 476                         erase->len = subdev->size - erase->addr;
 477                 else
 478                         erase->len = length;
 479
 480                 if (!(subdev->flags & MTD_WRITEABLE)) {
 481                         err = -EROFS;
 482                         break;
 483                 }
 484                 length -= erase->len;
 485                 if ((err = concat_dev_erase(subdev, erase))) {
 486                         /* sanity check: should never happen since
 487                          * block alignment has been checked above */
 488                         BUG_ON(err == -EINVAL);
 489                         if (erase->fail_addr != 0xffffffff)
 490                                 instr->fail_addr = erase->fail_addr + offset;
 491                         break;
 492                 }
 493                 /*
 494                  * erase->addr specifies the offset of the area to be
 495                  * erased *within the current subdevice*. It can be
 496                  * non-zero only the first time through this loop, i.e.
 497                  * for the first subdevice where blocks need to be erased.
 498                  * All the following erases must begin at the start of the
 499                  * current subdevice, i.e. at offset zero.
 500                  */
 501                 erase->addr = 0;
 502                 offset += subdev->size;
 503         }
 504         instr->state = erase->state;
 505         kfree(erase);
 506         if (err)
 507                 return err;
 508
 509         if (instr->callback)
 510                 instr->callback(instr);
 511         return 0;
 512 }
 513
 514 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
 515 {
 516         struct mtd_concat *concat = CONCAT(mtd);
 517         int i, err = -EINVAL;
 518
 519         if ((len + ofs) > mtd->size)
 520                 return -EINVAL;
 521
 522         for (i = 0; i < concat->num_subdev; i++) {
 523                 struct mtd_info *subdev = concat->subdev[i];
 524                 size_t size;
 525
 526                 if (ofs >= subdev->size) {
 527                         size = 0;
 528                         ofs -= subdev->size;
 529                         continue;
 530                 }
 531                 if (ofs + len > subdev->size)
 532                         size = subdev->size - ofs;
 533                 else
 534                         size = len;
 535
 536                 err = subdev->lock(subdev, ofs, size);
 537
 538                 if (err)
 539                         break;
 540
 541                 len -= size;
 542                 if (len == 0)
 543                         break;
 544
 545                 err = -EINVAL;
 546                 ofs = 0;
 547         }
 548
 549         return err;
 550 }
 551
 552 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
 553 {
 554         struct mtd_concat *concat = CONCAT(mtd);
 555         int i, err = 0;
 556
 557         if ((len + ofs) > mtd->size)
 558                 return -EINVAL;
 559
 560         for (i = 0; i < concat->num_subdev; i++) {
 561                 struct mtd_info *subdev = concat->subdev[i];
 562                 size_t size;
 563
 564                 if (ofs >= subdev->size) {
 565                         size = 0;
 566                         ofs -= subdev->size;
 567                         continue;
 568                 }
 569                 if (ofs + len > subdev->size)
 570                         size = subdev->size - ofs;
 571                 else
 572                         size = len;
 573
 574                 err = subdev->unlock(subdev, ofs, size);
 575
 576                 if (err)
 577                         break;
 578
 579                 len -= size;
 580                 if (len == 0)
 581                         break;
 582
 583                 err = -EINVAL;
 584                 ofs = 0;
 585         }
 586
 587         return err;
 588 }
 589
 590 static void concat_sync(struct mtd_info *mtd)
 591 {
 592         struct mtd_concat *concat = CONCAT(mtd);
 593         int i;
 594
 595         for (i = 0; i < concat->num_subdev; i++) {
 596                 struct mtd_info *subdev = concat->subdev[i];
 597                 subdev->sync(subdev);
 598         }
 599 }
 600
 601 static int concat_suspend(struct mtd_info *mtd)
 602 {
 603         struct mtd_concat *concat = CONCAT(mtd);
 604         int i, rc = 0;
 605
 606         for (i = 0; i < concat->num_subdev; i++) {
 607                 struct mtd_info *subdev = concat->subdev[i];
 608                 if ((rc = subdev->suspend(subdev)) < 0)
 609                         return rc;
 610         }
 611         return rc;
 612 }
 613
 614 static void concat_resume(struct mtd_info *mtd)
 615 {
 616         struct mtd_concat *concat = CONCAT(mtd);
 617         int i;
 618
 619         for (i = 0; i < concat->num_subdev; i++) {
 620                 struct mtd_info *subdev = concat->subdev[i];
 621                 subdev->resume(subdev);
 622         }
 623 }
 624
 625 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 626 {
 627         struct mtd_concat *concat = CONCAT(mtd);
 628         int i, res = 0;
 629
 630         if (!concat->subdev[0]->block_isbad)
 631                 return res;
 632
 633         if (ofs > mtd->size)
 634                 return -EINVAL;
 635
 636         for (i = 0; i < concat->num_subdev; i++) {
 637                 struct mtd_info *subdev = concat->subdev[i];
 638
 639                 if (ofs >= subdev->size) {
 640                         ofs -= subdev->size;
 641                         continue;
 642                 }
 643
 644                 res = subdev->block_isbad(subdev, ofs);
 645                 break;
 646         }
 647
 648         return res;
 649 }
 650
 651 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 652 {
 653         struct mtd_concat *concat = CONCAT(mtd);
 654         int i, err = -EINVAL;
 655
 656         if (!concat->subdev[0]->block_markbad)
 657                 return 0;
 658
 659         if (ofs > mtd->size)
 660                 return -EINVAL;
 661
 662         for (i = 0; i < concat->num_subdev; i++) {
 663                 struct mtd_info *subdev = concat->subdev[i];
 664
 665                 if (ofs >= subdev->size) {
 666                         ofs -= subdev->size;
 667                         continue;
 668                 }
 669
 670                 err = subdev->block_markbad(subdev, ofs);
 671                 if (!err)
 672                         mtd->ecc_stats.badblocks++;
 673                 break;
 674         }
 675
 676         return err;
 677 }
 678
 679 /*
 680  * This function constructs a virtual MTD device by concatenating
 681  * num_devs MTD devices. A pointer to the new device object is
 682  * stored to *new_dev upon success. This function does _not_
 683  * register any devices: this is the caller's responsibility.
 684  */
 685 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 686                                    int num_devs,        /* number of subdevices      */
 687                                    char *name)
 688 {                               /* name for the new device   */
 689         int i;
 690         size_t size;
 691         struct mtd_concat *concat;
 692         u_int32_t max_erasesize, curr_erasesize;
 693         int num_erase_region;
 694
 695         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 696         for (i = 0; i < num_devs; i++)
 697                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 698         printk(KERN_NOTICE "into device \"%s\"\n", name);
 699
 700         /* allocate the device structure */
 701         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 702         concat = kmalloc(size, GFP_KERNEL);
 703         if (!concat) {
 704                 printk
 705                     ("memory allocation error while creating concatenated device \"%s\"\n",
 706                      name);
 707                 return NULL;
 708         }
 709         memset(concat, 0, size);
 710         concat->subdev = (struct mtd_info **) (concat + 1);
 711
 712         /*
 713          * Set up the new "super" device's MTD object structure, check for
 714          * incompatibilites between the subdevices.
 715          */
 716         concat->mtd.type = subdev[0]->type;
 717         concat->mtd.flags = subdev[0]->flags;
 718         concat->mtd.size = subdev[0]->size;
 719         concat->mtd.erasesize = subdev[0]->erasesize;
 720         concat->mtd.writesize = subdev[0]->writesize;
 721         concat->mtd.oobsize = subdev[0]->oobsize;
 722         concat->mtd.ecctype = subdev[0]->ecctype;
 723         concat->mtd.eccsize = subdev[0]->eccsize;
 724         if (subdev[0]->writev)
 725                 concat->mtd.writev = concat_writev;
 726         if (subdev[0]->read_oob)
 727                 concat->mtd.read_oob = concat_read_oob;
 728         if (subdev[0]->write_oob)
 729                 concat->mtd.write_oob = concat_write_oob;
 730         if (subdev[0]->block_isbad)
 731                 concat->mtd.block_isbad = concat_block_isbad;
 732         if (subdev[0]->block_markbad)
 733                 concat->mtd.block_markbad = concat_block_markbad;
 734
 735         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 736
 737         concat->subdev[0] = subdev[0];
 738
 739         for (i = 1; i < num_devs; i++) {
 740                 if (concat->mtd.type != subdev[i]->type) {
 741                         kfree(concat);
 742                         printk("Incompatible device type on \"%s\"\n",
 743                                subdev[i]->name);
 744                         return NULL;
 745                 }
 746                 if (concat->mtd.flags != subdev[i]->flags) {
 747                         /*
 748                          * Expect all flags except MTD_WRITEABLE to be
 749                          * equal on all subdevices.
 750                          */
 751                         if ((concat->mtd.flags ^ subdev[i]->
 752                              flags) & ~MTD_WRITEABLE) {
 753                                 kfree(concat);
 754                                 printk("Incompatible device flags on \"%s\"\n",
 755                                        subdev[i]->name);
 756                                 return NULL;
 757                         } else
 758                                 /* if writeable attribute differs,
 759                                    make super device writeable */
 760                                 concat->mtd.flags |=
 761                                     subdev[i]->flags & MTD_WRITEABLE;
 762                 }
 763                 concat->mtd.size += subdev[i]->size;
 764                 concat->mtd.ecc_stats.badblocks +=
 765                         subdev[i]->ecc_stats.badblocks;
 766                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 767                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 768                     concat->mtd.ecctype    !=  subdev[i]->ecctype ||
 769                     concat->mtd.eccsize    !=  subdev[i]->eccsize ||
 770                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 771                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 772                         kfree(concat);
 773                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 774                                subdev[i]->name);
 775                         return NULL;
 776                 }
 777                 concat->subdev[i] = subdev[i];
 778
 779         }
 780
 781         concat->mtd.ecclayout = subdev[0]->ecclayout;
 782
 783         concat->num_subdev = num_devs;
 784         concat->mtd.name = name;
 785
 786         concat->mtd.erase = concat_erase;
 787         concat->mtd.read = concat_read;
 788         concat->mtd.write = concat_write;
 789         concat->mtd.sync = concat_sync;
 790         concat->mtd.lock = concat_lock;
 791         concat->mtd.unlock = concat_unlock;
 792         concat->mtd.suspend = concat_suspend;
 793         concat->mtd.resume = concat_resume;
 794
 795         /*
 796          * Combine the erase block size info of the subdevices:
 797          *
 798          * first, walk the map of the new device and see how
 799          * many changes in erase size we have
 800          */
 801         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 802         num_erase_region = 1;
 803         for (i = 0; i < num_devs; i++) {
 804                 if (subdev[i]->numeraseregions == 0) {
 805                         /* current subdevice has uniform erase size */
 806                         if (subdev[i]->erasesize != curr_erasesize) {
 807                                 /* if it differs from the last subdevice's erase size, count it */
 808                                 ++num_erase_region;
 809                                 curr_erasesize = subdev[i]->erasesize;
 810                                 if (curr_erasesize > max_erasesize)
 811                                         max_erasesize = curr_erasesize;
 812                         }
 813                 } else {
 814                         /* current subdevice has variable erase size */
 815                         int j;
 816                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 817
 818                                 /* walk the list of erase regions, count any changes */
 819                                 if (subdev[i]->eraseregions[j].erasesize !=
 820                                     curr_erasesize) {
 821                                         ++num_erase_region;
 822                                         curr_erasesize =
 823                                             subdev[i]->eraseregions[j].
 824                                             erasesize;
 825                                         if (curr_erasesize > max_erasesize)
 826                                                 max_erasesize = curr_erasesize;
 827                                 }
 828                         }
 829                 }
 830         }
 831
 832         if (num_erase_region == 1) {
 833                 /*
 834                  * All subdevices have the same uniform erase size.
 835                  * This is easy:
 836                  */
 837                 concat->mtd.erasesize = curr_erasesize;
 838                 concat->mtd.numeraseregions = 0;
 839         } else {
 840                 /*
 841                  * erase block size varies across the subdevices: allocate
 842                  * space to store the data describing the variable erase regions
 843                  */
 844                 struct mtd_erase_region_info *erase_region_p;
 845                 u_int32_t begin, position;
 846
 847                 concat->mtd.erasesize = max_erasesize;
 848                 concat->mtd.numeraseregions = num_erase_region;
 849                 concat->mtd.eraseregions = erase_region_p =
 850                     kmalloc(num_erase_region *
 851                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 852                 if (!erase_region_p) {
 853                         kfree(concat);
 854                         printk
 855                             ("memory allocation error while creating erase region list"
 856                              " for device \"%s\"\n", name);
 857                         return NULL;
 858                 }
 859
 860                 /*
 861                  * walk the map of the new device once more and fill in
 862                  * in erase region info:
 863                  */
 864                 curr_erasesize = subdev[0]->erasesize;
 865                 begin = position = 0;
 866                 for (i = 0; i < num_devs; i++) {
 867                         if (subdev[i]->numeraseregions == 0) {
 868                                 /* current subdevice has uniform erase size */
 869                                 if (subdev[i]->erasesize != curr_erasesize) {
 870                                         /*
 871                                          *  fill in an mtd_erase_region_info structure for the area
 872                                          *  we have walked so far:
 873                                          */
 874                                         erase_region_p->offset = begin;
 875                                         erase_region_p->erasesize =
 876                                             curr_erasesize;
 877                                         erase_region_p->numblocks =
 878                                             (position - begin) / curr_erasesize;
 879                                         begin = position;
 880
 881                                         curr_erasesize = subdev[i]->erasesize;
 882                                         ++erase_region_p;
 883                                 }
 884                                 position += subdev[i]->size;
 885                         } else {
 886                                 /* current subdevice has variable erase size */
 887                                 int j;
 888                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 889                                         /* walk the list of erase regions, count any changes */
 890                                         if (subdev[i]->eraseregions[j].
 891                                             erasesize != curr_erasesize) {
 892                                                 erase_region_p->offset = begin;
 893                                                 erase_region_p->erasesize =
 894                                                     curr_erasesize;
 895                                                 erase_region_p->numblocks =
 896                                                     (position -
 897                                                      begin) / curr_erasesize;
 898                                                 begin = position;
 899
 900                                                 curr_erasesize =
 901                                                     subdev[i]->eraseregions[j].
 902                                                     erasesize;
 903                                                 ++erase_region_p;
 904                                         }
 905                                         position +=
 906                                             subdev[i]->eraseregions[j].
 907                                             numblocks * curr_erasesize;
 908                                 }
 909                         }
 910                 }
 911                 /* Now write the final entry */
 912                 erase_region_p->offset = begin;
 913                 erase_region_p->erasesize = curr_erasesize;
 914                 erase_region_p->numblocks = (position - begin) / curr_erasesize;
 915         }
 916
 917         return &concat->mtd;
 918 }
 919
 920 /*
 921  * This function destroys an MTD object obtained from concat_mtd_devs()
 922  */
 923
 924 void mtd_concat_destroy(struct mtd_info *mtd)
 925 {
 926         struct mtd_concat *concat = CONCAT(mtd);
 927         if (concat->mtd.numeraseregions)
 928                 kfree(concat->mtd.eraseregions);
 929         kfree(concat);
 930 }
 931
 932 EXPORT_SYMBOL(mtd_concat_create);
 933 EXPORT_SYMBOL(mtd_concat_destroy);
 934
 935 MODULE_LICENSE("GPL");
 936 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 937 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");