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
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/sched.h>
  15 #include <linux/types.h>
  16 #include <linux/backing-dev.h>
  17
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/mtd/concat.h>
  20
  21 #include <asm/div64.h>
  22
  23 /*
  24  * Our storage structure:
  25  * Subdev points to an array of pointers to struct mtd_info objects
  26  * which is allocated along with this structure
  27  *
  28  */
  29 struct mtd_concat {
  30         struct mtd_info mtd;
  31         int num_subdev;
  32         struct mtd_info **subdev;
  33 };
  34
  35 /*
  36  * how to calculate the size required for the above structure,
  37  * including the pointer array subdev points to:
  38  */
  39 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  40         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  41
  42 /*
  43  * Given a pointer to the MTD object in the mtd_concat structure,
  44  * we can retrieve the pointer to that structure with this macro.
  45  */
  46 #define CONCAT(x)  ((struct mtd_concat *)(x))
  47
  48 /*
  49  * MTD methods which look up the relevant subdevice, translate the
  50  * effective address and pass through to the subdevice.
  51  */
  52
  53 static int
  54 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  55             size_t * retlen, u_char * buf)
  56 {
  57         struct mtd_concat *concat = CONCAT(mtd);
  58         int ret = 0, err;
  59         int i;
  60
  61         *retlen = 0;
  62
  63         for (i = 0; i < concat->num_subdev; i++) {
  64                 struct mtd_info *subdev = concat->subdev[i];
  65                 size_t size, retsize;
  66
  67                 if (from >= subdev->size) {
  68                         /* Not destined for this subdev */
  69                         size = 0;
  70                         from -= subdev->size;
  71                         continue;
  72                 }
  73                 if (from + len > subdev->size)
  74                         /* First part goes into this subdev */
  75                         size = subdev->size - from;
  76                 else
  77                         /* Entire transaction goes into this subdev */
  78                         size = len;
  79
  80                 err = subdev->read(subdev, from, size, &retsize, buf);
  81
  82                 /* Save information about bitflips! */
  83                 if (unlikely(err)) {
  84                         if (err == -EBADMSG) {
  85                                 mtd->ecc_stats.failed++;
  86                                 ret = err;
  87                         } else if (err == -EUCLEAN) {
  88                                 mtd->ecc_stats.corrected++;
  89                                 /* Do not overwrite -EBADMSG !! */
  90                                 if (!ret)
  91                                         ret = err;
  92                         } else
  93                                 return err;
  94                 }
  95
  96                 *retlen += retsize;
  97                 len -= size;
  98                 if (len == 0)
  99                         return ret;
 100
 101                 buf += size;
 102                 from = 0;
 103         }
 104         return -EINVAL;
 105 }
 106
 107 static int
 108 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 109              size_t * retlen, const u_char * buf)
 110 {
 111         struct mtd_concat *concat = CONCAT(mtd);
 112         int err = -EINVAL;
 113         int i;
 114
 115         if (!(mtd->flags & MTD_WRITEABLE))
 116                 return -EROFS;
 117
 118         *retlen = 0;
 119
 120         for (i = 0; i < concat->num_subdev; i++) {
 121                 struct mtd_info *subdev = concat->subdev[i];
 122                 size_t size, retsize;
 123
 124                 if (to >= subdev->size) {
 125                         size = 0;
 126                         to -= subdev->size;
 127                         continue;
 128                 }
 129                 if (to + len > subdev->size)
 130                         size = subdev->size - to;
 131                 else
 132                         size = len;
 133
 134                 if (!(subdev->flags & MTD_WRITEABLE))
 135                         err = -EROFS;
 136                 else
 137                         err = subdev->write(subdev, to, size, &retsize, buf);
 138
 139                 if (err)
 140                         break;
 141
 142                 *retlen += retsize;
 143                 len -= size;
 144                 if (len == 0)
 145                         break;
 146
 147                 err = -EINVAL;
 148                 buf += size;
 149                 to = 0;
 150         }
 151         return err;
 152 }
 153
 154 static int
 155 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 156                 unsigned long count, loff_t to, size_t * retlen)
 157 {
 158         struct mtd_concat *concat = CONCAT(mtd);
 159         struct kvec *vecs_copy;
 160         unsigned long entry_low, entry_high;
 161         size_t total_len = 0;
 162         int i;
 163         int err = -EINVAL;
 164
 165         if (!(mtd->flags & MTD_WRITEABLE))
 166                 return -EROFS;
 167
 168         *retlen = 0;
 169
 170         /* Calculate total length of data */
 171         for (i = 0; i < count; i++)
 172                 total_len += vecs[i].iov_len;
 173
 174         /* Do not allow write past end of device */
 175         if ((to + total_len) > mtd->size)
 176                 return -EINVAL;
 177
 178         /* Check alignment */
 179         if (mtd->writesize > 1) {
 180                 uint64_t __to = to;
 181                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
 182                         return -EINVAL;
 183         }
 184
 185         /* make a copy of vecs */
 186         vecs_copy = kmalloc(sizeof(struct kvec) * count, GFP_KERNEL);
 187         if (!vecs_copy)
 188                 return -ENOMEM;
 189         memcpy(vecs_copy, vecs, sizeof(struct kvec) * count);
 190
 191         entry_low = 0;
 192         for (i = 0; i < concat->num_subdev; i++) {
 193                 struct mtd_info *subdev = concat->subdev[i];
 194                 size_t size, wsize, retsize, old_iov_len;
 195
 196                 if (to >= subdev->size) {
 197                         to -= subdev->size;
 198                         continue;
 199                 }
 200
 201                 size = min_t(uint64_t, total_len, subdev->size - to);
 202                 wsize = size; /* store for future use */
 203
 204                 entry_high = entry_low;
 205                 while (entry_high < count) {
 206                         if (size <= vecs_copy[entry_high].iov_len)
 207                                 break;
 208                         size -= vecs_copy[entry_high++].iov_len;
 209                 }
 210
 211                 old_iov_len = vecs_copy[entry_high].iov_len;
 212                 vecs_copy[entry_high].iov_len = size;
 213
 214                 if (!(subdev->flags & MTD_WRITEABLE))
 215                         err = -EROFS;
 216                 else
 217                         err = subdev->writev(subdev, &vecs_copy[entry_low],
 218                                 entry_high - entry_low + 1, to, &retsize);
 219
 220                 vecs_copy[entry_high].iov_len = old_iov_len - size;
 221                 vecs_copy[entry_high].iov_base += size;
 222
 223                 entry_low = entry_high;
 224
 225                 if (err)
 226                         break;
 227
 228                 *retlen += retsize;
 229                 total_len -= wsize;
 230
 231                 if (total_len == 0)
 232                         break;
 233
 234                 err = -EINVAL;
 235                 to = 0;
 236         }
 237
 238         kfree(vecs_copy);
 239         return err;
 240 }
 241
 242 static int
 243 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 244 {
 245         struct mtd_concat *concat = CONCAT(mtd);
 246         struct mtd_oob_ops devops = *ops;
 247         int i, err, ret = 0;
 248
 249         ops->retlen = ops->oobretlen = 0;
 250
 251         for (i = 0; i < concat->num_subdev; i++) {
 252                 struct mtd_info *subdev = concat->subdev[i];
 253
 254                 if (from >= subdev->size) {
 255                         from -= subdev->size;
 256                         continue;
 257                 }
 258
 259                 /* partial read ? */
 260                 if (from + devops.len > subdev->size)
 261                         devops.len = subdev->size - from;
 262
 263                 err = subdev->read_oob(subdev, from, &devops);
 264                 ops->retlen += devops.retlen;
 265                 ops->oobretlen += devops.oobretlen;
 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                 if (devops.datbuf) {
 282                         devops.len = ops->len - ops->retlen;
 283                         if (!devops.len)
 284                                 return ret;
 285                         devops.datbuf += devops.retlen;
 286                 }
 287                 if (devops.oobbuf) {
 288                         devops.ooblen = ops->ooblen - ops->oobretlen;
 289                         if (!devops.ooblen)
 290                                 return ret;
 291                         devops.oobbuf += ops->oobretlen;
 292                 }
 293
 294                 from = 0;
 295         }
 296         return -EINVAL;
 297 }
 298
 299 static int
 300 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 301 {
 302         struct mtd_concat *concat = CONCAT(mtd);
 303         struct mtd_oob_ops devops = *ops;
 304         int i, err;
 305
 306         if (!(mtd->flags & MTD_WRITEABLE))
 307                 return -EROFS;
 308
 309         ops->retlen = 0;
 310
 311         for (i = 0; i < concat->num_subdev; i++) {
 312                 struct mtd_info *subdev = concat->subdev[i];
 313
 314                 if (to >= subdev->size) {
 315                         to -= subdev->size;
 316                         continue;
 317                 }
 318
 319                 /* partial write ? */
 320                 if (to + devops.len > subdev->size)
 321                         devops.len = subdev->size - to;
 322
 323                 err = subdev->write_oob(subdev, to, &devops);
 324                 ops->retlen += devops.retlen;
 325                 if (err)
 326                         return err;
 327
 328                 if (devops.datbuf) {
 329                         devops.len = ops->len - ops->retlen;
 330                         if (!devops.len)
 331                                 return 0;
 332                         devops.datbuf += devops.retlen;
 333                 }
 334                 if (devops.oobbuf) {
 335                         devops.ooblen = ops->ooblen - ops->oobretlen;
 336                         if (!devops.ooblen)
 337                                 return 0;
 338                         devops.oobbuf += devops.oobretlen;
 339                 }
 340                 to = 0;
 341         }
 342         return -EINVAL;
 343 }
 344
 345 static void concat_erase_callback(struct erase_info *instr)
 346 {
 347         wake_up((wait_queue_head_t *) instr->priv);
 348 }
 349
 350 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 351 {
 352         int err;
 353         wait_queue_head_t waitq;
 354         DECLARE_WAITQUEUE(wait, current);
 355
 356         /*
 357          * This code was stol^H^H^H^Hinspired by mtdchar.c
 358          */
 359         init_waitqueue_head(&waitq);
 360
 361         erase->mtd = mtd;
 362         erase->callback = concat_erase_callback;
 363         erase->priv = (unsigned long) &waitq;
 364
 365         /*
 366          * FIXME: Allow INTERRUPTIBLE. Which means
 367          * not having the wait_queue head on the stack.
 368          */
 369         err = mtd->erase(mtd, erase);
 370         if (!err) {
 371                 set_current_state(TASK_UNINTERRUPTIBLE);
 372                 add_wait_queue(&waitq, &wait);
 373                 if (erase->state != MTD_ERASE_DONE
 374                     && erase->state != MTD_ERASE_FAILED)
 375                         schedule();
 376                 remove_wait_queue(&waitq, &wait);
 377                 set_current_state(TASK_RUNNING);
 378
 379                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 380         }
 381         return err;
 382 }
 383
 384 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 385 {
 386         struct mtd_concat *concat = CONCAT(mtd);
 387         struct mtd_info *subdev;
 388         int i, err;
 389         uint64_t length, offset = 0;
 390         struct erase_info *erase;
 391
 392         if (!(mtd->flags & MTD_WRITEABLE))
 393                 return -EROFS;
 394
 395         if (instr->addr > concat->mtd.size)
 396                 return -EINVAL;
 397
 398         if (instr->len + instr->addr > concat->mtd.size)
 399                 return -EINVAL;
 400
 401         /*
 402          * Check for proper erase block alignment of the to-be-erased area.
 403          * It is easier to do this based on the super device's erase
 404          * region info rather than looking at each particular sub-device
 405          * in turn.
 406          */
 407         if (!concat->mtd.numeraseregions) {
 408                 /* the easy case: device has uniform erase block size */
 409                 if (instr->addr & (concat->mtd.erasesize - 1))
 410                         return -EINVAL;
 411                 if (instr->len & (concat->mtd.erasesize - 1))
 412                         return -EINVAL;
 413         } else {
 414                 /* device has variable erase size */
 415                 struct mtd_erase_region_info *erase_regions =
 416                     concat->mtd.eraseregions;
 417
 418                 /*
 419                  * Find the erase region where the to-be-erased area begins:
 420                  */
 421                 for (i = 0; i < concat->mtd.numeraseregions &&
 422                      instr->addr >= erase_regions[i].offset; i++) ;
 423                 --i;
 424
 425                 /*
 426                  * Now erase_regions[i] is the region in which the
 427                  * to-be-erased area begins. Verify that the starting
 428                  * offset is aligned to this region's erase size:
 429                  */
 430                 if (i < 0 || instr->addr & (erase_regions[i].erasesize - 1))
 431                         return -EINVAL;
 432
 433                 /*
 434                  * now find the erase region where the to-be-erased area ends:
 435                  */
 436                 for (; i < concat->mtd.numeraseregions &&
 437                      (instr->addr + instr->len) >= erase_regions[i].offset;
 438                      ++i) ;
 439                 --i;
 440                 /*
 441                  * check if the ending offset is aligned to this region's erase size
 442                  */
 443                 if (i < 0 || ((instr->addr + instr->len) &
 444                                         (erase_regions[i].erasesize - 1)))
 445                         return -EINVAL;
 446         }
 447
 448         instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
 449
 450         /* make a local copy of instr to avoid modifying the caller's struct */
 451         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 452
 453         if (!erase)
 454                 return -ENOMEM;
 455
 456         *erase = *instr;
 457         length = instr->len;
 458
 459         /*
 460          * find the subdevice where the to-be-erased area begins, adjust
 461          * starting offset to be relative to the subdevice start
 462          */
 463         for (i = 0; i < concat->num_subdev; i++) {
 464                 subdev = concat->subdev[i];
 465                 if (subdev->size <= erase->addr) {
 466                         erase->addr -= subdev->size;
 467                         offset += subdev->size;
 468                 } else {
 469                         break;
 470                 }
 471         }
 472
 473         /* must never happen since size limit has been verified above */
 474         BUG_ON(i >= concat->num_subdev);
 475
 476         /* now do the erase: */
 477         err = 0;
 478         for (; length > 0; i++) {
 479                 /* loop for all subdevices affected by this request */
 480                 subdev = concat->subdev[i];     /* get current subdevice */
 481
 482                 /* limit length to subdevice's size: */
 483                 if (erase->addr + length > subdev->size)
 484                         erase->len = subdev->size - erase->addr;
 485                 else
 486                         erase->len = length;
 487
 488                 if (!(subdev->flags & MTD_WRITEABLE)) {
 489                         err = -EROFS;
 490                         break;
 491                 }
 492                 length -= erase->len;
 493                 if ((err = concat_dev_erase(subdev, erase))) {
 494                         /* sanity check: should never happen since
 495                          * block alignment has been checked above */
 496                         BUG_ON(err == -EINVAL);
 497                         if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
 498                                 instr->fail_addr = erase->fail_addr + offset;
 499                         break;
 500                 }
 501                 /*
 502                  * erase->addr specifies the offset of the area to be
 503                  * erased *within the current subdevice*. It can be
 504                  * non-zero only the first time through this loop, i.e.
 505                  * for the first subdevice where blocks need to be erased.
 506                  * All the following erases must begin at the start of the
 507                  * current subdevice, i.e. at offset zero.
 508                  */
 509                 erase->addr = 0;
 510                 offset += subdev->size;
 511         }
 512         instr->state = erase->state;
 513         kfree(erase);
 514         if (err)
 515                 return err;
 516
 517         if (instr->callback)
 518                 instr->callback(instr);
 519         return 0;
 520 }
 521
 522 static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 523 {
 524         struct mtd_concat *concat = CONCAT(mtd);
 525         int i, err = -EINVAL;
 526
 527         if ((len + ofs) > mtd->size)
 528                 return -EINVAL;
 529
 530         for (i = 0; i < concat->num_subdev; i++) {
 531                 struct mtd_info *subdev = concat->subdev[i];
 532                 uint64_t size;
 533
 534                 if (ofs >= subdev->size) {
 535                         size = 0;
 536                         ofs -= subdev->size;
 537                         continue;
 538                 }
 539                 if (ofs + len > subdev->size)
 540                         size = subdev->size - ofs;
 541                 else
 542                         size = len;
 543
 544                 err = subdev->lock(subdev, ofs, size);
 545
 546                 if (err)
 547                         break;
 548
 549                 len -= size;
 550                 if (len == 0)
 551                         break;
 552
 553                 err = -EINVAL;
 554                 ofs = 0;
 555         }
 556
 557         return err;
 558 }
 559
 560 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 561 {
 562         struct mtd_concat *concat = CONCAT(mtd);
 563         int i, err = 0;
 564
 565         if ((len + ofs) > mtd->size)
 566                 return -EINVAL;
 567
 568         for (i = 0; i < concat->num_subdev; i++) {
 569                 struct mtd_info *subdev = concat->subdev[i];
 570                 uint64_t size;
 571
 572                 if (ofs >= subdev->size) {
 573                         size = 0;
 574                         ofs -= subdev->size;
 575                         continue;
 576                 }
 577                 if (ofs + len > subdev->size)
 578                         size = subdev->size - ofs;
 579                 else
 580                         size = len;
 581
 582                 err = subdev->unlock(subdev, ofs, size);
 583
 584                 if (err)
 585                         break;
 586
 587                 len -= size;
 588                 if (len == 0)
 589                         break;
 590
 591                 err = -EINVAL;
 592                 ofs = 0;
 593         }
 594
 595         return err;
 596 }
 597
 598 static void concat_sync(struct mtd_info *mtd)
 599 {
 600         struct mtd_concat *concat = CONCAT(mtd);
 601         int i;
 602
 603         for (i = 0; i < concat->num_subdev; i++) {
 604                 struct mtd_info *subdev = concat->subdev[i];
 605                 subdev->sync(subdev);
 606         }
 607 }
 608
 609 static int concat_suspend(struct mtd_info *mtd)
 610 {
 611         struct mtd_concat *concat = CONCAT(mtd);
 612         int i, rc = 0;
 613
 614         for (i = 0; i < concat->num_subdev; i++) {
 615                 struct mtd_info *subdev = concat->subdev[i];
 616                 if ((rc = subdev->suspend(subdev)) < 0)
 617                         return rc;
 618         }
 619         return rc;
 620 }
 621
 622 static void concat_resume(struct mtd_info *mtd)
 623 {
 624         struct mtd_concat *concat = CONCAT(mtd);
 625         int i;
 626
 627         for (i = 0; i < concat->num_subdev; i++) {
 628                 struct mtd_info *subdev = concat->subdev[i];
 629                 subdev->resume(subdev);
 630         }
 631 }
 632
 633 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 634 {
 635         struct mtd_concat *concat = CONCAT(mtd);
 636         int i, res = 0;
 637
 638         if (!concat->subdev[0]->block_isbad)
 639                 return res;
 640
 641         if (ofs > mtd->size)
 642                 return -EINVAL;
 643
 644         for (i = 0; i < concat->num_subdev; i++) {
 645                 struct mtd_info *subdev = concat->subdev[i];
 646
 647                 if (ofs >= subdev->size) {
 648                         ofs -= subdev->size;
 649                         continue;
 650                 }
 651
 652                 res = subdev->block_isbad(subdev, ofs);
 653                 break;
 654         }
 655
 656         return res;
 657 }
 658
 659 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 660 {
 661         struct mtd_concat *concat = CONCAT(mtd);
 662         int i, err = -EINVAL;
 663
 664         if (!concat->subdev[0]->block_markbad)
 665                 return 0;
 666
 667         if (ofs > mtd->size)
 668                 return -EINVAL;
 669
 670         for (i = 0; i < concat->num_subdev; i++) {
 671                 struct mtd_info *subdev = concat->subdev[i];
 672
 673                 if (ofs >= subdev->size) {
 674                         ofs -= subdev->size;
 675                         continue;
 676                 }
 677
 678                 err = subdev->block_markbad(subdev, ofs);
 679                 if (!err)
 680                         mtd->ecc_stats.badblocks++;
 681                 break;
 682         }
 683
 684         return err;
 685 }
 686
 687 /*
 688  * try to support NOMMU mmaps on concatenated devices
 689  * - we don't support subdev spanning as we can't guarantee it'll work
 690  */
 691 static unsigned long concat_get_unmapped_area(struct mtd_info *mtd,
 692                                               unsigned long len,
 693                                               unsigned long offset,
 694                                               unsigned long flags)
 695 {
 696         struct mtd_concat *concat = CONCAT(mtd);
 697         int i;
 698
 699         for (i = 0; i < concat->num_subdev; i++) {
 700                 struct mtd_info *subdev = concat->subdev[i];
 701
 702                 if (offset >= subdev->size) {
 703                         offset -= subdev->size;
 704                         continue;
 705                 }
 706
 707                 /* we've found the subdev over which the mapping will reside */
 708                 if (offset + len > subdev->size)
 709                         return (unsigned long) -EINVAL;
 710
 711                 if (subdev->get_unmapped_area)
 712                         return subdev->get_unmapped_area(subdev, len, offset,
 713                                                          flags);
 714
 715                 break;
 716         }
 717
 718         return (unsigned long) -ENOSYS;
 719 }
 720
 721 /*
 722  * This function constructs a virtual MTD device by concatenating
 723  * num_devs MTD devices. A pointer to the new device object is
 724  * stored to *new_dev upon success. This function does _not_
 725  * register any devices: this is the caller's responsibility.
 726  */
 727 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 728                                    int num_devs,        /* number of subdevices      */
 729                                    const char *name)
 730 {                               /* name for the new device   */
 731         int i;
 732         size_t size;
 733         struct mtd_concat *concat;
 734         uint32_t max_erasesize, curr_erasesize;
 735         int num_erase_region;
 736
 737         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 738         for (i = 0; i < num_devs; i++)
 739                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 740         printk(KERN_NOTICE "into device \"%s\"\n", name);
 741
 742         /* allocate the device structure */
 743         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 744         concat = kzalloc(size, GFP_KERNEL);
 745         if (!concat) {
 746                 printk
 747                     ("memory allocation error while creating concatenated device \"%s\"\n",
 748                      name);
 749                 return NULL;
 750         }
 751         concat->subdev = (struct mtd_info **) (concat + 1);
 752
 753         /*
 754          * Set up the new "super" device's MTD object structure, check for
 755          * incompatibilites between the subdevices.
 756          */
 757         concat->mtd.type = subdev[0]->type;
 758         concat->mtd.flags = subdev[0]->flags;
 759         concat->mtd.size = subdev[0]->size;
 760         concat->mtd.erasesize = subdev[0]->erasesize;
 761         concat->mtd.writesize = subdev[0]->writesize;
 762         concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 763         concat->mtd.oobsize = subdev[0]->oobsize;
 764         concat->mtd.oobavail = subdev[0]->oobavail;
 765         if (subdev[0]->writev)
 766                 concat->mtd.writev = concat_writev;
 767         if (subdev[0]->read_oob)
 768                 concat->mtd.read_oob = concat_read_oob;
 769         if (subdev[0]->write_oob)
 770                 concat->mtd.write_oob = concat_write_oob;
 771         if (subdev[0]->block_isbad)
 772                 concat->mtd.block_isbad = concat_block_isbad;
 773         if (subdev[0]->block_markbad)
 774                 concat->mtd.block_markbad = concat_block_markbad;
 775
 776         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 777
 778         concat->mtd.backing_dev_info = subdev[0]->backing_dev_info;
 779
 780         concat->subdev[0] = subdev[0];
 781
 782         for (i = 1; i < num_devs; i++) {
 783                 if (concat->mtd.type != subdev[i]->type) {
 784                         kfree(concat);
 785                         printk("Incompatible device type on \"%s\"\n",
 786                                subdev[i]->name);
 787                         return NULL;
 788                 }
 789                 if (concat->mtd.flags != subdev[i]->flags) {
 790                         /*
 791                          * Expect all flags except MTD_WRITEABLE to be
 792                          * equal on all subdevices.
 793                          */
 794                         if ((concat->mtd.flags ^ subdev[i]->
 795                              flags) & ~MTD_WRITEABLE) {
 796                                 kfree(concat);
 797                                 printk("Incompatible device flags on \"%s\"\n",
 798                                        subdev[i]->name);
 799                                 return NULL;
 800                         } else
 801                                 /* if writeable attribute differs,
 802                                    make super device writeable */
 803                                 concat->mtd.flags |=
 804                                     subdev[i]->flags & MTD_WRITEABLE;
 805                 }
 806
 807                 /* only permit direct mapping if the BDIs are all the same
 808                  * - copy-mapping is still permitted
 809                  */
 810                 if (concat->mtd.backing_dev_info !=
 811                     subdev[i]->backing_dev_info)
 812                         concat->mtd.backing_dev_info =
 813                                 &default_backing_dev_info;
 814
 815                 concat->mtd.size += subdev[i]->size;
 816                 concat->mtd.ecc_stats.badblocks +=
 817                         subdev[i]->ecc_stats.badblocks;
 818                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 819                     concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 820                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 821                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 822                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 823                         kfree(concat);
 824                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 825                                subdev[i]->name);
 826                         return NULL;
 827                 }
 828                 concat->subdev[i] = subdev[i];
 829
 830         }
 831
 832         concat->mtd.ecclayout = subdev[0]->ecclayout;
 833
 834         concat->num_subdev = num_devs;
 835         concat->mtd.name = name;
 836
 837         concat->mtd.erase = concat_erase;
 838         concat->mtd.read = concat_read;
 839         concat->mtd.write = concat_write;
 840         concat->mtd.sync = concat_sync;
 841         concat->mtd.lock = concat_lock;
 842         concat->mtd.unlock = concat_unlock;
 843         concat->mtd.suspend = concat_suspend;
 844         concat->mtd.resume = concat_resume;
 845         concat->mtd.get_unmapped_area = concat_get_unmapped_area;
 846
 847         /*
 848          * Combine the erase block size info of the subdevices:
 849          *
 850          * first, walk the map of the new device and see how
 851          * many changes in erase size we have
 852          */
 853         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 854         num_erase_region = 1;
 855         for (i = 0; i < num_devs; i++) {
 856                 if (subdev[i]->numeraseregions == 0) {
 857                         /* current subdevice has uniform erase size */
 858                         if (subdev[i]->erasesize != curr_erasesize) {
 859                                 /* if it differs from the last subdevice's erase size, count it */
 860                                 ++num_erase_region;
 861                                 curr_erasesize = subdev[i]->erasesize;
 862                                 if (curr_erasesize > max_erasesize)
 863                                         max_erasesize = curr_erasesize;
 864                         }
 865                 } else {
 866                         /* current subdevice has variable erase size */
 867                         int j;
 868                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 869
 870                                 /* walk the list of erase regions, count any changes */
 871                                 if (subdev[i]->eraseregions[j].erasesize !=
 872                                     curr_erasesize) {
 873                                         ++num_erase_region;
 874                                         curr_erasesize =
 875                                             subdev[i]->eraseregions[j].
 876                                             erasesize;
 877                                         if (curr_erasesize > max_erasesize)
 878                                                 max_erasesize = curr_erasesize;
 879                                 }
 880                         }
 881                 }
 882         }
 883
 884         if (num_erase_region == 1) {
 885                 /*
 886                  * All subdevices have the same uniform erase size.
 887                  * This is easy:
 888                  */
 889                 concat->mtd.erasesize = curr_erasesize;
 890                 concat->mtd.numeraseregions = 0;
 891         } else {
 892                 uint64_t tmp64;
 893
 894                 /*
 895                  * erase block size varies across the subdevices: allocate
 896                  * space to store the data describing the variable erase regions
 897                  */
 898                 struct mtd_erase_region_info *erase_region_p;
 899                 uint64_t begin, position;
 900
 901                 concat->mtd.erasesize = max_erasesize;
 902                 concat->mtd.numeraseregions = num_erase_region;
 903                 concat->mtd.eraseregions = erase_region_p =
 904                     kmalloc(num_erase_region *
 905                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 906                 if (!erase_region_p) {
 907                         kfree(concat);
 908                         printk
 909                             ("memory allocation error while creating erase region list"
 910                              " for device \"%s\"\n", name);
 911                         return NULL;
 912                 }
 913
 914                 /*
 915                  * walk the map of the new device once more and fill in
 916                  * in erase region info:
 917                  */
 918                 curr_erasesize = subdev[0]->erasesize;
 919                 begin = position = 0;
 920                 for (i = 0; i < num_devs; i++) {
 921                         if (subdev[i]->numeraseregions == 0) {
 922                                 /* current subdevice has uniform erase size */
 923                                 if (subdev[i]->erasesize != curr_erasesize) {
 924                                         /*
 925                                          *  fill in an mtd_erase_region_info structure for the area
 926                                          *  we have walked so far:
 927                                          */
 928                                         erase_region_p->offset = begin;
 929                                         erase_region_p->erasesize =
 930                                             curr_erasesize;
 931                                         tmp64 = position - begin;
 932                                         do_div(tmp64, curr_erasesize);
 933                                         erase_region_p->numblocks = tmp64;
 934                                         begin = position;
 935
 936                                         curr_erasesize = subdev[i]->erasesize;
 937                                         ++erase_region_p;
 938                                 }
 939                                 position += subdev[i]->size;
 940                         } else {
 941                                 /* current subdevice has variable erase size */
 942                                 int j;
 943                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 944                                         /* walk the list of erase regions, count any changes */
 945                                         if (subdev[i]->eraseregions[j].
 946                                             erasesize != curr_erasesize) {
 947                                                 erase_region_p->offset = begin;
 948                                                 erase_region_p->erasesize =
 949                                                     curr_erasesize;
 950                                                 tmp64 = position - begin;
 951                                                 do_div(tmp64, curr_erasesize);
 952                                                 erase_region_p->numblocks = tmp64;
 953                                                 begin = position;
 954
 955                                                 curr_erasesize =
 956                                                     subdev[i]->eraseregions[j].
 957                                                     erasesize;
 958                                                 ++erase_region_p;
 959                                         }
 960                                         position +=
 961                                             subdev[i]->eraseregions[j].
 962                                             numblocks * (uint64_t)curr_erasesize;
 963                                 }
 964                         }
 965                 }
 966                 /* Now write the final entry */
 967                 erase_region_p->offset = begin;
 968                 erase_region_p->erasesize = curr_erasesize;
 969                 tmp64 = position - begin;
 970                 do_div(tmp64, curr_erasesize);
 971                 erase_region_p->numblocks = tmp64;
 972         }
 973
 974         return &concat->mtd;
 975 }
 976
 977 /*
 978  * This function destroys an MTD object obtained from concat_mtd_devs()
 979  */
 980
 981 void mtd_concat_destroy(struct mtd_info *mtd)
 982 {
 983         struct mtd_concat *concat = CONCAT(mtd);
 984         if (concat->mtd.numeraseregions)
 985                 kfree(concat->mtd.eraseregions);
 986         kfree(concat);
 987 }
 988
 989 EXPORT_SYMBOL(mtd_concat_create);
 990 EXPORT_SYMBOL(mtd_concat_destroy);
 991
 992 MODULE_LICENSE("GPL");
 993 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 994 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");