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
  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
  17 #include <linux/mtd/mtd.h>
  18 #include <linux/mtd/concat.h>
  19
  20 #include <asm/div64.h>
  21
  22 /*
  23  * Our storage structure:
  24  * Subdev points to an array of pointers to struct mtd_info objects
  25  * which is allocated along with this structure
  26  *
  27  */
  28 struct mtd_concat {
  29         struct mtd_info mtd;
  30         int num_subdev;
  31         struct mtd_info **subdev;
  32 };
  33
  34 /*
  35  * how to calculate the size required for the above structure,
  36  * including the pointer array subdev points to:
  37  */
  38 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  39         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  40
  41 /*
  42  * Given a pointer to the MTD object in the mtd_concat structure,
  43  * we can retrieve the pointer to that structure with this macro.
  44  */
  45 #define CONCAT(x)  ((struct mtd_concat *)(x))
  46
  47 /*
  48  * MTD methods which look up the relevant subdevice, translate the
  49  * effective address and pass through to the subdevice.
  50  */
  51
  52 static int
  53 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  54             size_t * retlen, u_char * buf)
  55 {
  56         struct mtd_concat *concat = CONCAT(mtd);
  57         int ret = 0, err;
  58         int i;
  59
  60         *retlen = 0;
  61
  62         for (i = 0; i < concat->num_subdev; i++) {
  63                 struct mtd_info *subdev = concat->subdev[i];
  64                 size_t size, retsize;
  65
  66                 if (from >= subdev->size) {
  67                         /* Not destined for this subdev */
  68                         size = 0;
  69                         from -= subdev->size;
  70                         continue;
  71                 }
  72                 if (from + len > subdev->size)
  73                         /* First part goes into this subdev */
  74                         size = subdev->size - from;
  75                 else
  76                         /* Entire transaction goes into this subdev */
  77                         size = len;
  78
  79                 err = subdev->read(subdev, from, size, &retsize, buf);
  80
  81                 /* Save information about bitflips! */
  82                 if (unlikely(err)) {
  83                         if (err == -EBADMSG) {
  84                                 mtd->ecc_stats.failed++;
  85                                 ret = err;
  86                         } else if (err == -EUCLEAN) {
  87                                 mtd->ecc_stats.corrected++;
  88                                 /* Do not overwrite -EBADMSG !! */
  89                                 if (!ret)
  90                                         ret = err;
  91                         } else
  92                                 return err;
  93                 }
  94
  95                 *retlen += retsize;
  96                 len -= size;
  97                 if (len == 0)
  98                         return ret;
  99
 100                 buf += size;
 101                 from = 0;
 102         }
 103         return -EINVAL;
 104 }
 105
 106 static int
 107 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 108              size_t * retlen, const u_char * buf)
 109 {
 110         struct mtd_concat *concat = CONCAT(mtd);
 111         int err = -EINVAL;
 112         int i;
 113
 114         if (!(mtd->flags & MTD_WRITEABLE))
 115                 return -EROFS;
 116
 117         *retlen = 0;
 118
 119         for (i = 0; i < concat->num_subdev; i++) {
 120                 struct mtd_info *subdev = concat->subdev[i];
 121                 size_t size, retsize;
 122
 123                 if (to >= subdev->size) {
 124                         size = 0;
 125                         to -= subdev->size;
 126                         continue;
 127                 }
 128                 if (to + len > subdev->size)
 129                         size = subdev->size - to;
 130                 else
 131                         size = len;
 132
 133                 if (!(subdev->flags & MTD_WRITEABLE))
 134                         err = -EROFS;
 135                 else
 136                         err = subdev->write(subdev, to, size, &retsize, buf);
 137
 138                 if (err)
 139                         break;
 140
 141                 *retlen += retsize;
 142                 len -= size;
 143                 if (len == 0)
 144                         break;
 145
 146                 err = -EINVAL;
 147                 buf += size;
 148                 to = 0;
 149         }
 150         return err;
 151 }
 152
 153 static int
 154 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 155                 unsigned long count, loff_t to, size_t * retlen)
 156 {
 157         struct mtd_concat *concat = CONCAT(mtd);
 158         struct kvec *vecs_copy;
 159         unsigned long entry_low, entry_high;
 160         size_t total_len = 0;
 161         int i;
 162         int err = -EINVAL;
 163
 164         if (!(mtd->flags & MTD_WRITEABLE))
 165                 return -EROFS;
 166
 167         *retlen = 0;
 168
 169         /* Calculate total length of data */
 170         for (i = 0; i < count; i++)
 171                 total_len += vecs[i].iov_len;
 172
 173         /* Do not allow write past end of device */
 174         if ((to + total_len) > mtd->size)
 175                 return -EINVAL;
 176
 177         /* Check alignment */
 178         if (mtd->writesize > 1) {
 179                 uint64_t __to = to;
 180                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
 181                         return -EINVAL;
 182         }
 183
 184         /* make a copy of vecs */
 185         vecs_copy = kmalloc(sizeof(struct kvec) * count, GFP_KERNEL);
 186         if (!vecs_copy)
 187                 return -ENOMEM;
 188         memcpy(vecs_copy, vecs, sizeof(struct kvec) * count);
 189
 190         entry_low = 0;
 191         for (i = 0; i < concat->num_subdev; i++) {
 192                 struct mtd_info *subdev = concat->subdev[i];
 193                 size_t size, wsize, retsize, old_iov_len;
 194
 195                 if (to >= subdev->size) {
 196                         to -= subdev->size;
 197                         continue;
 198                 }
 199
 200                 size = min(total_len, (size_t)(subdev->size - to));
 201                 wsize = size; /* store for future use */
 202
 203                 entry_high = entry_low;
 204                 while (entry_high < count) {
 205                         if (size <= vecs_copy[entry_high].iov_len)
 206                                 break;
 207                         size -= vecs_copy[entry_high++].iov_len;
 208                 }
 209
 210                 old_iov_len = vecs_copy[entry_high].iov_len;
 211                 vecs_copy[entry_high].iov_len = size;
 212
 213                 if (!(subdev->flags & MTD_WRITEABLE))
 214                         err = -EROFS;
 215                 else
 216                         err = subdev->writev(subdev, &vecs_copy[entry_low],
 217                                 entry_high - entry_low + 1, to, &retsize);
 218
 219                 vecs_copy[entry_high].iov_len = old_iov_len - size;
 220                 vecs_copy[entry_high].iov_base += size;
 221
 222                 entry_low = entry_high;
 223
 224                 if (err)
 225                         break;
 226
 227                 *retlen += retsize;
 228                 total_len -= wsize;
 229
 230                 if (total_len == 0)
 231                         break;
 232
 233                 err = -EINVAL;
 234                 to = 0;
 235         }
 236
 237         kfree(vecs_copy);
 238         return err;
 239 }
 240
 241 static int
 242 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 243 {
 244         struct mtd_concat *concat = CONCAT(mtd);
 245         struct mtd_oob_ops devops = *ops;
 246         int i, err, ret = 0;
 247
 248         ops->retlen = ops->oobretlen = 0;
 249
 250         for (i = 0; i < concat->num_subdev; i++) {
 251                 struct mtd_info *subdev = concat->subdev[i];
 252
 253                 if (from >= subdev->size) {
 254                         from -= subdev->size;
 255                         continue;
 256                 }
 257
 258                 /* partial read ? */
 259                 if (from + devops.len > subdev->size)
 260                         devops.len = subdev->size - from;
 261
 262                 err = subdev->read_oob(subdev, from, &devops);
 263                 ops->retlen += devops.retlen;
 264                 ops->oobretlen += devops.oobretlen;
 265
 266                 /* Save information about bitflips! */
 267                 if (unlikely(err)) {
 268                         if (err == -EBADMSG) {
 269                                 mtd->ecc_stats.failed++;
 270                                 ret = err;
 271                         } else if (err == -EUCLEAN) {
 272                                 mtd->ecc_stats.corrected++;
 273                                 /* Do not overwrite -EBADMSG !! */
 274                                 if (!ret)
 275                                         ret = err;
 276                         } else
 277                                 return err;
 278                 }
 279
 280                 if (devops.datbuf) {
 281                         devops.len = ops->len - ops->retlen;
 282                         if (!devops.len)
 283                                 return ret;
 284                         devops.datbuf += devops.retlen;
 285                 }
 286                 if (devops.oobbuf) {
 287                         devops.ooblen = ops->ooblen - ops->oobretlen;
 288                         if (!devops.ooblen)
 289                                 return ret;
 290                         devops.oobbuf += ops->oobretlen;
 291                 }
 292
 293                 from = 0;
 294         }
 295         return -EINVAL;
 296 }
 297
 298 static int
 299 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 300 {
 301         struct mtd_concat *concat = CONCAT(mtd);
 302         struct mtd_oob_ops devops = *ops;
 303         int i, err;
 304
 305         if (!(mtd->flags & MTD_WRITEABLE))
 306                 return -EROFS;
 307
 308         ops->retlen = 0;
 309
 310         for (i = 0; i < concat->num_subdev; i++) {
 311                 struct mtd_info *subdev = concat->subdev[i];
 312
 313                 if (to >= subdev->size) {
 314                         to -= subdev->size;
 315                         continue;
 316                 }
 317
 318                 /* partial write ? */
 319                 if (to + devops.len > subdev->size)
 320                         devops.len = subdev->size - to;
 321
 322                 err = subdev->write_oob(subdev, to, &devops);
 323                 ops->retlen += devops.retlen;
 324                 if (err)
 325                         return err;
 326
 327                 if (devops.datbuf) {
 328                         devops.len = ops->len - ops->retlen;
 329                         if (!devops.len)
 330                                 return 0;
 331                         devops.datbuf += devops.retlen;
 332                 }
 333                 if (devops.oobbuf) {
 334                         devops.ooblen = ops->ooblen - ops->oobretlen;
 335                         if (!devops.ooblen)
 336                                 return 0;
 337                         devops.oobbuf += devops.oobretlen;
 338                 }
 339                 to = 0;
 340         }
 341         return -EINVAL;
 342 }
 343
 344 static void concat_erase_callback(struct erase_info *instr)
 345 {
 346         wake_up((wait_queue_head_t *) instr->priv);
 347 }
 348
 349 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 350 {
 351         int err;
 352         wait_queue_head_t waitq;
 353         DECLARE_WAITQUEUE(wait, current);
 354
 355         /*
 356          * This code was stol^H^H^H^Hinspired by mtdchar.c
 357          */
 358         init_waitqueue_head(&waitq);
 359
 360         erase->mtd = mtd;
 361         erase->callback = concat_erase_callback;
 362         erase->priv = (unsigned long) &waitq;
 363
 364         /*
 365          * FIXME: Allow INTERRUPTIBLE. Which means
 366          * not having the wait_queue head on the stack.
 367          */
 368         err = mtd->erase(mtd, erase);
 369         if (!err) {
 370                 set_current_state(TASK_UNINTERRUPTIBLE);
 371                 add_wait_queue(&waitq, &wait);
 372                 if (erase->state != MTD_ERASE_DONE
 373                     && erase->state != MTD_ERASE_FAILED)
 374                         schedule();
 375                 remove_wait_queue(&waitq, &wait);
 376                 set_current_state(TASK_RUNNING);
 377
 378                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 379         }
 380         return err;
 381 }
 382
 383 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 384 {
 385         struct mtd_concat *concat = CONCAT(mtd);
 386         struct mtd_info *subdev;
 387         int i, err;
 388         u_int32_t length, offset = 0;
 389         struct erase_info *erase;
 390
 391         if (!(mtd->flags & MTD_WRITEABLE))
 392                 return -EROFS;
 393
 394         if (instr->addr > concat->mtd.size)
 395                 return -EINVAL;
 396
 397         if (instr->len + instr->addr > concat->mtd.size)
 398                 return -EINVAL;
 399
 400         /*
 401          * Check for proper erase block alignment of the to-be-erased area.
 402          * It is easier to do this based on the super device's erase
 403          * region info rather than looking at each particular sub-device
 404          * in turn.
 405          */
 406         if (!concat->mtd.numeraseregions) {
 407                 /* the easy case: device has uniform erase block size */
 408                 if (instr->addr & (concat->mtd.erasesize - 1))
 409                         return -EINVAL;
 410                 if (instr->len & (concat->mtd.erasesize - 1))
 411                         return -EINVAL;
 412         } else {
 413                 /* device has variable erase size */
 414                 struct mtd_erase_region_info *erase_regions =
 415                     concat->mtd.eraseregions;
 416
 417                 /*
 418                  * Find the erase region where the to-be-erased area begins:
 419                  */
 420                 for (i = 0; i < concat->mtd.numeraseregions &&
 421                      instr->addr >= erase_regions[i].offset; i++) ;
 422                 --i;
 423
 424                 /*
 425                  * Now erase_regions[i] is the region in which the
 426                  * to-be-erased area begins. Verify that the starting
 427                  * offset is aligned to this region's erase size:
 428                  */
 429                 if (instr->addr & (erase_regions[i].erasesize - 1))
 430                         return -EINVAL;
 431
 432                 /*
 433                  * now find the erase region where the to-be-erased area ends:
 434                  */
 435                 for (; i < concat->mtd.numeraseregions &&
 436                      (instr->addr + instr->len) >= erase_regions[i].offset;
 437                      ++i) ;
 438                 --i;
 439                 /*
 440                  * check if the ending offset is aligned to this region's erase size
 441                  */
 442                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 443                                                   1))
 444                         return -EINVAL;
 445         }
 446
 447         instr->fail_addr = 0xffffffff;
 448
 449         /* make a local copy of instr to avoid modifying the caller's struct */
 450         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 451
 452         if (!erase)
 453                 return -ENOMEM;
 454
 455         *erase = *instr;
 456         length = instr->len;
 457
 458         /*
 459          * find the subdevice where the to-be-erased area begins, adjust
 460          * starting offset to be relative to the subdevice start
 461          */
 462         for (i = 0; i < concat->num_subdev; i++) {
 463                 subdev = concat->subdev[i];
 464                 if (subdev->size <= erase->addr) {
 465                         erase->addr -= subdev->size;
 466                         offset += subdev->size;
 467                 } else {
 468                         break;
 469                 }
 470         }
 471
 472         /* must never happen since size limit has been verified above */
 473         BUG_ON(i >= concat->num_subdev);
 474
 475         /* now do the erase: */
 476         err = 0;
 477         for (; length > 0; i++) {
 478                 /* loop for all subdevices affected by this request */
 479                 subdev = concat->subdev[i];     /* get current subdevice */
 480
 481                 /* limit length to subdevice's size: */
 482                 if (erase->addr + length > subdev->size)
 483                         erase->len = subdev->size - erase->addr;
 484                 else
 485                         erase->len = length;
 486
 487                 if (!(subdev->flags & MTD_WRITEABLE)) {
 488                         err = -EROFS;
 489                         break;
 490                 }
 491                 length -= erase->len;
 492                 if ((err = concat_dev_erase(subdev, erase))) {
 493                         /* sanity check: should never happen since
 494                          * block alignment has been checked above */
 495                         BUG_ON(err == -EINVAL);
 496                         if (erase->fail_addr != 0xffffffff)
 497                                 instr->fail_addr = erase->fail_addr + offset;
 498                         break;
 499                 }
 500                 /*
 501                  * erase->addr specifies the offset of the area to be
 502                  * erased *within the current subdevice*. It can be
 503                  * non-zero only the first time through this loop, i.e.
 504                  * for the first subdevice where blocks need to be erased.
 505                  * All the following erases must begin at the start of the
 506                  * current subdevice, i.e. at offset zero.
 507                  */
 508                 erase->addr = 0;
 509                 offset += subdev->size;
 510         }
 511         instr->state = erase->state;
 512         kfree(erase);
 513         if (err)
 514                 return err;
 515
 516         if (instr->callback)
 517                 instr->callback(instr);
 518         return 0;
 519 }
 520
 521 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
 522 {
 523         struct mtd_concat *concat = CONCAT(mtd);
 524         int i, err = -EINVAL;
 525
 526         if ((len + ofs) > mtd->size)
 527                 return -EINVAL;
 528
 529         for (i = 0; i < concat->num_subdev; i++) {
 530                 struct mtd_info *subdev = concat->subdev[i];
 531                 size_t size;
 532
 533                 if (ofs >= subdev->size) {
 534                         size = 0;
 535                         ofs -= subdev->size;
 536                         continue;
 537                 }
 538                 if (ofs + len > subdev->size)
 539                         size = subdev->size - ofs;
 540                 else
 541                         size = len;
 542
 543                 err = subdev->lock(subdev, ofs, size);
 544
 545                 if (err)
 546                         break;
 547
 548                 len -= size;
 549                 if (len == 0)
 550                         break;
 551
 552                 err = -EINVAL;
 553                 ofs = 0;
 554         }
 555
 556         return err;
 557 }
 558
 559 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
 560 {
 561         struct mtd_concat *concat = CONCAT(mtd);
 562         int i, err = 0;
 563
 564         if ((len + ofs) > mtd->size)
 565                 return -EINVAL;
 566
 567         for (i = 0; i < concat->num_subdev; i++) {
 568                 struct mtd_info *subdev = concat->subdev[i];
 569                 size_t size;
 570
 571                 if (ofs >= subdev->size) {
 572                         size = 0;
 573                         ofs -= subdev->size;
 574                         continue;
 575                 }
 576                 if (ofs + len > subdev->size)
 577                         size = subdev->size - ofs;
 578                 else
 579                         size = len;
 580
 581                 err = subdev->unlock(subdev, ofs, size);
 582
 583                 if (err)
 584                         break;
 585
 586                 len -= size;
 587                 if (len == 0)
 588                         break;
 589
 590                 err = -EINVAL;
 591                 ofs = 0;
 592         }
 593
 594         return err;
 595 }
 596
 597 static void concat_sync(struct mtd_info *mtd)
 598 {
 599         struct mtd_concat *concat = CONCAT(mtd);
 600         int i;
 601
 602         for (i = 0; i < concat->num_subdev; i++) {
 603                 struct mtd_info *subdev = concat->subdev[i];
 604                 subdev->sync(subdev);
 605         }
 606 }
 607
 608 static int concat_suspend(struct mtd_info *mtd)
 609 {
 610         struct mtd_concat *concat = CONCAT(mtd);
 611         int i, rc = 0;
 612
 613         for (i = 0; i < concat->num_subdev; i++) {
 614                 struct mtd_info *subdev = concat->subdev[i];
 615                 if ((rc = subdev->suspend(subdev)) < 0)
 616                         return rc;
 617         }
 618         return rc;
 619 }
 620
 621 static void concat_resume(struct mtd_info *mtd)
 622 {
 623         struct mtd_concat *concat = CONCAT(mtd);
 624         int i;
 625
 626         for (i = 0; i < concat->num_subdev; i++) {
 627                 struct mtd_info *subdev = concat->subdev[i];
 628                 subdev->resume(subdev);
 629         }
 630 }
 631
 632 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 633 {
 634         struct mtd_concat *concat = CONCAT(mtd);
 635         int i, res = 0;
 636
 637         if (!concat->subdev[0]->block_isbad)
 638                 return res;
 639
 640         if (ofs > mtd->size)
 641                 return -EINVAL;
 642
 643         for (i = 0; i < concat->num_subdev; i++) {
 644                 struct mtd_info *subdev = concat->subdev[i];
 645
 646                 if (ofs >= subdev->size) {
 647                         ofs -= subdev->size;
 648                         continue;
 649                 }
 650
 651                 res = subdev->block_isbad(subdev, ofs);
 652                 break;
 653         }
 654
 655         return res;
 656 }
 657
 658 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 659 {
 660         struct mtd_concat *concat = CONCAT(mtd);
 661         int i, err = -EINVAL;
 662
 663         if (!concat->subdev[0]->block_markbad)
 664                 return 0;
 665
 666         if (ofs > mtd->size)
 667                 return -EINVAL;
 668
 669         for (i = 0; i < concat->num_subdev; i++) {
 670                 struct mtd_info *subdev = concat->subdev[i];
 671
 672                 if (ofs >= subdev->size) {
 673                         ofs -= subdev->size;
 674                         continue;
 675                 }
 676
 677                 err = subdev->block_markbad(subdev, ofs);
 678                 if (!err)
 679                         mtd->ecc_stats.badblocks++;
 680                 break;
 681         }
 682
 683         return err;
 684 }
 685
 686 /*
 687  * This function constructs a virtual MTD device by concatenating
 688  * num_devs MTD devices. A pointer to the new device object is
 689  * stored to *new_dev upon success. This function does _not_
 690  * register any devices: this is the caller's responsibility.
 691  */
 692 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 693                                    int num_devs,        /* number of subdevices      */
 694                                    char *name)
 695 {                               /* name for the new device   */
 696         int i;
 697         size_t size;
 698         struct mtd_concat *concat;
 699         u_int32_t max_erasesize, curr_erasesize;
 700         int num_erase_region;
 701
 702         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 703         for (i = 0; i < num_devs; i++)
 704                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 705         printk(KERN_NOTICE "into device \"%s\"\n", name);
 706
 707         /* allocate the device structure */
 708         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 709         concat = kzalloc(size, GFP_KERNEL);
 710         if (!concat) {
 711                 printk
 712                     ("memory allocation error while creating concatenated device \"%s\"\n",
 713                      name);
 714                 return NULL;
 715         }
 716         concat->subdev = (struct mtd_info **) (concat + 1);
 717
 718         /*
 719          * Set up the new "super" device's MTD object structure, check for
 720          * incompatibilites between the subdevices.
 721          */
 722         concat->mtd.type = subdev[0]->type;
 723         concat->mtd.flags = subdev[0]->flags;
 724         concat->mtd.size = subdev[0]->size;
 725         concat->mtd.erasesize = subdev[0]->erasesize;
 726         concat->mtd.writesize = subdev[0]->writesize;
 727         concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 728         concat->mtd.oobsize = subdev[0]->oobsize;
 729         concat->mtd.oobavail = subdev[0]->oobavail;
 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");