git.oblomov.eu Git - linux-2.6/blob - 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 = ops->oobretlen = 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                 ops->oobretlen += devops.oobretlen;
 267
 268                 /* Save information about bitflips! */
 269                 if (unlikely(err)) {
 270                         if (err == -EBADMSG) {
 271                                 mtd->ecc_stats.failed++;
 272                                 ret = err;
 273                         } else if (err == -EUCLEAN) {
 274                                 mtd->ecc_stats.corrected++;
 275                                 /* Do not overwrite -EBADMSG !! */
 276                                 if (!ret)
 277                                         ret = err;
 278                         } else
 279                                 return err;
 280                 }
 281
 282                 if (devops.datbuf) {
 283                         devops.len = ops->len - ops->retlen;
 284                         if (!devops.len)
 285                                 return ret;
 286                         devops.datbuf += devops.retlen;
 287                 }
 288                 if (devops.oobbuf) {
 289                         devops.ooblen = ops->ooblen - ops->oobretlen;
 290                         if (!devops.ooblen)
 291                                 return ret;
 292                         devops.oobbuf += ops->oobretlen;
 293                 }
 294
 295                 from = 0;
 296         }
 297         return -EINVAL;
 298 }
 299
 300 static int
 301 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 302 {
 303         struct mtd_concat *concat = CONCAT(mtd);
 304         struct mtd_oob_ops devops = *ops;
 305         int i, err;
 306
 307         if (!(mtd->flags & MTD_WRITEABLE))
 308                 return -EROFS;
 309
 310         ops->retlen = 0;
 311
 312         for (i = 0; i < concat->num_subdev; i++) {
 313                 struct mtd_info *subdev = concat->subdev[i];
 314
 315                 if (to >= subdev->size) {
 316                         to -= subdev->size;
 317                         continue;
 318                 }
 319
 320                 /* partial write ? */
 321                 if (to + devops.len > subdev->size)
 322                         devops.len = subdev->size - to;
 323
 324                 err = subdev->write_oob(subdev, to, &devops);
 325                 ops->retlen += devops.retlen;
 326                 if (err)
 327                         return err;
 328
 329                 if (devops.datbuf) {
 330                         devops.len = ops->len - ops->retlen;
 331                         if (!devops.len)
 332                                 return 0;
 333                         devops.datbuf += devops.retlen;
 334                 }
 335                 if (devops.oobbuf) {
 336                         devops.ooblen = ops->ooblen - ops->oobretlen;
 337                         if (!devops.ooblen)
 338                                 return 0;
 339                         devops.oobbuf += devops.oobretlen;
 340                 }
 341                 to = 0;
 342         }
 343         return -EINVAL;
 344 }
 345
 346 static void concat_erase_callback(struct erase_info *instr)
 347 {
 348         wake_up((wait_queue_head_t *) instr->priv);
 349 }
 350
 351 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 352 {
 353         int err;
 354         wait_queue_head_t waitq;
 355         DECLARE_WAITQUEUE(wait, current);
 356
 357         /*
 358          * This code was stol^H^H^H^Hinspired by mtdchar.c
 359          */
 360         init_waitqueue_head(&waitq);
 361
 362         erase->mtd = mtd;
 363         erase->callback = concat_erase_callback;
 364         erase->priv = (unsigned long) &waitq;
 365
 366         /*
 367          * FIXME: Allow INTERRUPTIBLE. Which means
 368          * not having the wait_queue head on the stack.
 369          */
 370         err = mtd->erase(mtd, erase);
 371         if (!err) {
 372                 set_current_state(TASK_UNINTERRUPTIBLE);
 373                 add_wait_queue(&waitq, &wait);
 374                 if (erase->state != MTD_ERASE_DONE
 375                     && erase->state != MTD_ERASE_FAILED)
 376                         schedule();
 377                 remove_wait_queue(&waitq, &wait);
 378                 set_current_state(TASK_RUNNING);
 379
 380                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 381         }
 382         return err;
 383 }
 384
 385 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 386 {
 387         struct mtd_concat *concat = CONCAT(mtd);
 388         struct mtd_info *subdev;
 389         int i, err;
 390         u_int32_t length, offset = 0;
 391         struct erase_info *erase;
 392
 393         if (!(mtd->flags & MTD_WRITEABLE))
 394                 return -EROFS;
 395
 396         if (instr->addr > concat->mtd.size)
 397                 return -EINVAL;
 398
 399         if (instr->len + instr->addr > concat->mtd.size)
 400                 return -EINVAL;
 401
 402         /*
 403          * Check for proper erase block alignment of the to-be-erased area.
 404          * It is easier to do this based on the super device's erase
 405          * region info rather than looking at each particular sub-device
 406          * in turn.
 407          */
 408         if (!concat->mtd.numeraseregions) {
 409                 /* the easy case: device has uniform erase block size */
 410                 if (instr->addr & (concat->mtd.erasesize - 1))
 411                         return -EINVAL;
 412                 if (instr->len & (concat->mtd.erasesize - 1))
 413                         return -EINVAL;
 414         } else {
 415                 /* device has variable erase size */
 416                 struct mtd_erase_region_info *erase_regions =
 417                     concat->mtd.eraseregions;
 418
 419                 /*
 420                  * Find the erase region where the to-be-erased area begins:
 421                  */
 422                 for (i = 0; i < concat->mtd.numeraseregions &&
 423                      instr->addr >= erase_regions[i].offset; i++) ;
 424                 --i;
 425
 426                 /*
 427                  * Now erase_regions[i] is the region in which the
 428                  * to-be-erased area begins. Verify that the starting
 429                  * offset is aligned to this region's erase size:
 430                  */
 431                 if (instr->addr & (erase_regions[i].erasesize - 1))
 432                         return -EINVAL;
 433
 434                 /*
 435                  * now find the erase region where the to-be-erased area ends:
 436                  */
 437                 for (; i < concat->mtd.numeraseregions &&
 438                      (instr->addr + instr->len) >= erase_regions[i].offset;
 439                      ++i) ;
 440                 --i;
 441                 /*
 442                  * check if the ending offset is aligned to this region's erase size
 443                  */
 444                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 445                                                   1))
 446                         return -EINVAL;
 447         }
 448
 449         instr->fail_addr = 0xffffffff;
 450
 451         /* make a local copy of instr to avoid modifying the caller's struct */
 452         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 453
 454         if (!erase)
 455                 return -ENOMEM;
 456
 457         *erase = *instr;
 458         length = instr->len;
 459
 460         /*
 461          * find the subdevice where the to-be-erased area begins, adjust
 462          * starting offset to be relative to the subdevice start
 463          */
 464         for (i = 0; i < concat->num_subdev; i++) {
 465                 subdev = concat->subdev[i];
 466                 if (subdev->size <= erase->addr) {
 467                         erase->addr -= subdev->size;
 468                         offset += subdev->size;
 469                 } else {
 470                         break;
 471                 }
 472         }
 473
 474         /* must never happen since size limit has been verified above */
 475         BUG_ON(i >= concat->num_subdev);
 476
 477         /* now do the erase: */
 478         err = 0;
 479         for (; length > 0; i++) {
 480                 /* loop for all subdevices affected by this request */
 481                 subdev = concat->subdev[i];     /* get current subdevice */
 482
 483                 /* limit length to subdevice's size: */
 484                 if (erase->addr + length > subdev->size)
 485                         erase->len = subdev->size - erase->addr;
 486                 else
 487                         erase->len = length;
 488
 489                 if (!(subdev->flags & MTD_WRITEABLE)) {
 490                         err = -EROFS;
 491                         break;
 492                 }
 493                 length -= erase->len;
 494                 if ((err = concat_dev_erase(subdev, erase))) {
 495                         /* sanity check: should never happen since
 496                          * block alignment has been checked above */
 497                         BUG_ON(err == -EINVAL);
 498                         if (erase->fail_addr != 0xffffffff)
 499                                 instr->fail_addr = erase->fail_addr + offset;
 500                         break;
 501                 }
 502                 /*
 503                  * erase->addr specifies the offset of the area to be
 504                  * erased *within the current subdevice*. It can be
 505                  * non-zero only the first time through this loop, i.e.
 506                  * for the first subdevice where blocks need to be erased.
 507                  * All the following erases must begin at the start of the
 508                  * current subdevice, i.e. at offset zero.
 509                  */
 510                 erase->addr = 0;
 511                 offset += subdev->size;
 512         }
 513         instr->state = erase->state;
 514         kfree(erase);
 515         if (err)
 516                 return err;
 517
 518         if (instr->callback)
 519                 instr->callback(instr);
 520         return 0;
 521 }
 522
 523 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
 524 {
 525         struct mtd_concat *concat = CONCAT(mtd);
 526         int i, err = -EINVAL;
 527
 528         if ((len + ofs) > mtd->size)
 529                 return -EINVAL;
 530
 531         for (i = 0; i < concat->num_subdev; i++) {
 532                 struct mtd_info *subdev = concat->subdev[i];
 533                 size_t size;
 534
 535                 if (ofs >= subdev->size) {
 536                         size = 0;
 537                         ofs -= subdev->size;
 538                         continue;
 539                 }
 540                 if (ofs + len > subdev->size)
 541                         size = subdev->size - ofs;
 542                 else
 543                         size = len;
 544
 545                 err = subdev->lock(subdev, ofs, size);
 546
 547                 if (err)
 548                         break;
 549
 550                 len -= size;
 551                 if (len == 0)
 552                         break;
 553
 554                 err = -EINVAL;
 555                 ofs = 0;
 556         }
 557
 558         return err;
 559 }
 560
 561 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
 562 {
 563         struct mtd_concat *concat = CONCAT(mtd);
 564         int i, err = 0;
 565
 566         if ((len + ofs) > mtd->size)
 567                 return -EINVAL;
 568
 569         for (i = 0; i < concat->num_subdev; i++) {
 570                 struct mtd_info *subdev = concat->subdev[i];
 571                 size_t size;
 572
 573                 if (ofs >= subdev->size) {
 574                         size = 0;
 575                         ofs -= subdev->size;
 576                         continue;
 577                 }
 578                 if (ofs + len > subdev->size)
 579                         size = subdev->size - ofs;
 580                 else
 581                         size = len;
 582
 583                 err = subdev->unlock(subdev, ofs, size);
 584
 585                 if (err)
 586                         break;
 587
 588                 len -= size;
 589                 if (len == 0)
 590                         break;
 591
 592                 err = -EINVAL;
 593                 ofs = 0;
 594         }
 595
 596         return err;
 597 }
 598
 599 static void concat_sync(struct mtd_info *mtd)
 600 {
 601         struct mtd_concat *concat = CONCAT(mtd);
 602         int i;
 603
 604         for (i = 0; i < concat->num_subdev; i++) {
 605                 struct mtd_info *subdev = concat->subdev[i];
 606                 subdev->sync(subdev);
 607         }
 608 }
 609
 610 static int concat_suspend(struct mtd_info *mtd)
 611 {
 612         struct mtd_concat *concat = CONCAT(mtd);
 613         int i, rc = 0;
 614
 615         for (i = 0; i < concat->num_subdev; i++) {
 616                 struct mtd_info *subdev = concat->subdev[i];
 617                 if ((rc = subdev->suspend(subdev)) < 0)
 618                         return rc;
 619         }
 620         return rc;
 621 }
 622
 623 static void concat_resume(struct mtd_info *mtd)
 624 {
 625         struct mtd_concat *concat = CONCAT(mtd);
 626         int i;
 627
 628         for (i = 0; i < concat->num_subdev; i++) {
 629                 struct mtd_info *subdev = concat->subdev[i];
 630                 subdev->resume(subdev);
 631         }
 632 }
 633
 634 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 635 {
 636         struct mtd_concat *concat = CONCAT(mtd);
 637         int i, res = 0;
 638
 639         if (!concat->subdev[0]->block_isbad)
 640                 return res;
 641
 642         if (ofs > mtd->size)
 643                 return -EINVAL;
 644
 645         for (i = 0; i < concat->num_subdev; i++) {
 646                 struct mtd_info *subdev = concat->subdev[i];
 647
 648                 if (ofs >= subdev->size) {
 649                         ofs -= subdev->size;
 650                         continue;
 651                 }
 652
 653                 res = subdev->block_isbad(subdev, ofs);
 654                 break;
 655         }
 656
 657         return res;
 658 }
 659
 660 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 661 {
 662         struct mtd_concat *concat = CONCAT(mtd);
 663         int i, err = -EINVAL;
 664
 665         if (!concat->subdev[0]->block_markbad)
 666                 return 0;
 667
 668         if (ofs > mtd->size)
 669                 return -EINVAL;
 670
 671         for (i = 0; i < concat->num_subdev; i++) {
 672                 struct mtd_info *subdev = concat->subdev[i];
 673
 674                 if (ofs >= subdev->size) {
 675                         ofs -= subdev->size;
 676                         continue;
 677                 }
 678
 679                 err = subdev->block_markbad(subdev, ofs);
 680                 if (!err)
 681                         mtd->ecc_stats.badblocks++;
 682                 break;
 683         }
 684
 685         return err;
 686 }
 687
 688 /*
 689  * This function constructs a virtual MTD device by concatenating
 690  * num_devs MTD devices. A pointer to the new device object is
 691  * stored to *new_dev upon success. This function does _not_
 692  * register any devices: this is the caller's responsibility.
 693  */
 694 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 695                                    int num_devs,        /* number of subdevices      */
 696                                    char *name)
 697 {                               /* name for the new device   */
 698         int i;
 699         size_t size;
 700         struct mtd_concat *concat;
 701         u_int32_t max_erasesize, curr_erasesize;
 702         int num_erase_region;
 703
 704         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 705         for (i = 0; i < num_devs; i++)
 706                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 707         printk(KERN_NOTICE "into device \"%s\"\n", name);
 708
 709         /* allocate the device structure */
 710         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 711         concat = kzalloc(size, GFP_KERNEL);
 712         if (!concat) {
 713                 printk
 714                     ("memory allocation error while creating concatenated device \"%s\"\n",
 715                      name);
 716                 return NULL;
 717         }
 718         concat->subdev = (struct mtd_info **) (concat + 1);
 719
 720         /*
 721          * Set up the new "super" device's MTD object structure, check for
 722          * incompatibilites between the subdevices.
 723          */
 724         concat->mtd.type = subdev[0]->type;
 725         concat->mtd.flags = subdev[0]->flags;
 726         concat->mtd.size = subdev[0]->size;
 727         concat->mtd.erasesize = subdev[0]->erasesize;
 728         concat->mtd.writesize = subdev[0]->writesize;
 729         concat->mtd.oobsize = subdev[0]->oobsize;
 730         if (subdev[0]->writev)
 731                 concat->mtd.writev = concat_writev;
 732         if (subdev[0]->read_oob)
 733                 concat->mtd.read_oob = concat_read_oob;
 734         if (subdev[0]->write_oob)
 735                 concat->mtd.write_oob = concat_write_oob;
 736         if (subdev[0]->block_isbad)
 737                 concat->mtd.block_isbad = concat_block_isbad;
 738         if (subdev[0]->block_markbad)
 739                 concat->mtd.block_markbad = concat_block_markbad;
 740
 741         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 742
 743         concat->subdev[0] = subdev[0];
 744
 745         for (i = 1; i < num_devs; i++) {
 746                 if (concat->mtd.type != subdev[i]->type) {
 747                         kfree(concat);
 748                         printk("Incompatible device type on \"%s\"\n",
 749                                subdev[i]->name);
 750                         return NULL;
 751                 }
 752                 if (concat->mtd.flags != subdev[i]->flags) {
 753                         /*
 754                          * Expect all flags except MTD_WRITEABLE to be
 755                          * equal on all subdevices.
 756                          */
 757                         if ((concat->mtd.flags ^ subdev[i]->
 758                              flags) & ~MTD_WRITEABLE) {
 759                                 kfree(concat);
 760                                 printk("Incompatible device flags on \"%s\"\n",
 761                                        subdev[i]->name);
 762                                 return NULL;
 763                         } else
 764                                 /* if writeable attribute differs,
 765                                    make super device writeable */
 766                                 concat->mtd.flags |=
 767                                     subdev[i]->flags & MTD_WRITEABLE;
 768                 }
 769                 concat->mtd.size += subdev[i]->size;
 770                 concat->mtd.ecc_stats.badblocks +=
 771                         subdev[i]->ecc_stats.badblocks;
 772                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 773                     concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 774                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 775                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 776                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 777                         kfree(concat);
 778                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 779                                subdev[i]->name);
 780                         return NULL;
 781                 }
 782                 concat->subdev[i] = subdev[i];
 783
 784         }
 785
 786         concat->mtd.ecclayout = subdev[0]->ecclayout;
 787
 788         concat->num_subdev = num_devs;
 789         concat->mtd.name = name;
 790
 791         concat->mtd.erase = concat_erase;
 792         concat->mtd.read = concat_read;
 793         concat->mtd.write = concat_write;
 794         concat->mtd.sync = concat_sync;
 795         concat->mtd.lock = concat_lock;
 796         concat->mtd.unlock = concat_unlock;
 797         concat->mtd.suspend = concat_suspend;
 798         concat->mtd.resume = concat_resume;
 799
 800         /*
 801          * Combine the erase block size info of the subdevices:
 802          *
 803          * first, walk the map of the new device and see how
 804          * many changes in erase size we have
 805          */
 806         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 807         num_erase_region = 1;
 808         for (i = 0; i < num_devs; i++) {
 809                 if (subdev[i]->numeraseregions == 0) {
 810                         /* current subdevice has uniform erase size */
 811                         if (subdev[i]->erasesize != curr_erasesize) {
 812                                 /* if it differs from the last subdevice's erase size, count it */
 813                                 ++num_erase_region;
 814                                 curr_erasesize = subdev[i]->erasesize;
 815                                 if (curr_erasesize > max_erasesize)
 816                                         max_erasesize = curr_erasesize;
 817                         }
 818                 } else {
 819                         /* current subdevice has variable erase size */
 820                         int j;
 821                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 822
 823                                 /* walk the list of erase regions, count any changes */
 824                                 if (subdev[i]->eraseregions[j].erasesize !=
 825                                     curr_erasesize) {
 826                                         ++num_erase_region;
 827                                         curr_erasesize =
 828                                             subdev[i]->eraseregions[j].
 829                                             erasesize;
 830                                         if (curr_erasesize > max_erasesize)
 831                                                 max_erasesize = curr_erasesize;
 832                                 }
 833                         }
 834                 }
 835         }
 836
 837         if (num_erase_region == 1) {
 838                 /*
 839                  * All subdevices have the same uniform erase size.
 840                  * This is easy:
 841                  */
 842                 concat->mtd.erasesize = curr_erasesize;
 843                 concat->mtd.numeraseregions = 0;
 844         } else {
 845                 /*
 846                  * erase block size varies across the subdevices: allocate
 847                  * space to store the data describing the variable erase regions
 848                  */
 849                 struct mtd_erase_region_info *erase_region_p;
 850                 u_int32_t begin, position;
 851
 852                 concat->mtd.erasesize = max_erasesize;
 853                 concat->mtd.numeraseregions = num_erase_region;
 854                 concat->mtd.eraseregions = erase_region_p =
 855                     kmalloc(num_erase_region *
 856                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 857                 if (!erase_region_p) {
 858                         kfree(concat);
 859                         printk
 860                             ("memory allocation error while creating erase region list"
 861                              " for device \"%s\"\n", name);
 862                         return NULL;
 863                 }
 864
 865                 /*
 866                  * walk the map of the new device once more and fill in
 867                  * in erase region info:
 868                  */
 869                 curr_erasesize = subdev[0]->erasesize;
 870                 begin = position = 0;
 871                 for (i = 0; i < num_devs; i++) {
 872                         if (subdev[i]->numeraseregions == 0) {
 873                                 /* current subdevice has uniform erase size */
 874                                 if (subdev[i]->erasesize != curr_erasesize) {
 875                                         /*
 876                                          *  fill in an mtd_erase_region_info structure for the area
 877                                          *  we have walked so far:
 878                                          */
 879                                         erase_region_p->offset = begin;
 880                                         erase_region_p->erasesize =
 881                                             curr_erasesize;
 882                                         erase_region_p->numblocks =
 883                                             (position - begin) / curr_erasesize;
 884                                         begin = position;
 885
 886                                         curr_erasesize = subdev[i]->erasesize;
 887                                         ++erase_region_p;
 888                                 }
 889                                 position += subdev[i]->size;
 890                         } else {
 891                                 /* current subdevice has variable erase size */
 892                                 int j;
 893                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 894                                         /* walk the list of erase regions, count any changes */
 895                                         if (subdev[i]->eraseregions[j].
 896                                             erasesize != curr_erasesize) {
 897                                                 erase_region_p->offset = begin;
 898                                                 erase_region_p->erasesize =
 899                                                     curr_erasesize;
 900                                                 erase_region_p->numblocks =
 901                                                     (position -
 902                                                      begin) / curr_erasesize;
 903                                                 begin = position;
 904
 905                                                 curr_erasesize =
 906                                                     subdev[i]->eraseregions[j].
 907                                                     erasesize;
 908                                                 ++erase_region_p;
 909                                         }
 910                                         position +=
 911                                             subdev[i]->eraseregions[j].
 912                                             numblocks * curr_erasesize;
 913                                 }
 914                         }
 915                 }
 916                 /* Now write the final entry */
 917                 erase_region_p->offset = begin;
 918                 erase_region_p->erasesize = curr_erasesize;
 919                 erase_region_p->numblocks = (position - begin) / curr_erasesize;
 920         }
 921
 922         return &concat->mtd;
 923 }
 924
 925 /*
 926  * This function destroys an MTD object obtained from concat_mtd_devs()
 927  */
 928
 929 void mtd_concat_destroy(struct mtd_info *mtd)
 930 {
 931         struct mtd_concat *concat = CONCAT(mtd);
 932         if (concat->mtd.numeraseregions)
 933                 kfree(concat->mtd.eraseregions);
 934         kfree(concat);
 935 }
 936
 937 EXPORT_SYMBOL(mtd_concat_create);
 938 EXPORT_SYMBOL(mtd_concat_destroy);
 939
 940 MODULE_LICENSE("GPL");
 941 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 942 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");