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   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 1.9 2004/06/30 15:17:41 dbrown Exp $
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/slab.h>
  17
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/mtd/concat.h>
  20
  21 /*
  22  * Our storage structure:
  23  * Subdev points to an array of pointers to struct mtd_info objects
  24  * which is allocated along with this structure
  25  *
  26  */
  27 struct mtd_concat {
  28         struct mtd_info mtd;
  29         int num_subdev;
  30         struct mtd_info **subdev;
  31 };
  32
  33 /*
  34  * how to calculate the size required for the above structure,
  35  * including the pointer array subdev points to:
  36  */
  37 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  38         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  39
  40 /*
  41  * Given a pointer to the MTD object in the mtd_concat structure,
  42  * we can retrieve the pointer to that structure with this macro.
  43  */
  44 #define CONCAT(x)  ((struct mtd_concat *)(x))
  45
  46 /*
  47  * MTD methods which look up the relevant subdevice, translate the
  48  * effective address and pass through to the subdevice.
  49  */
  50
  51 static int
  52 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  53             size_t * retlen, u_char * buf)
  54 {
  55         struct mtd_concat *concat = CONCAT(mtd);
  56         int err = -EINVAL;
  57         int i;
  58
  59         *retlen = 0;
  60
  61         for (i = 0; i < concat->num_subdev; i++) {
  62                 struct mtd_info *subdev = concat->subdev[i];
  63                 size_t size, retsize;
  64
  65                 if (from >= subdev->size) {
  66                         /* Not destined for this subdev */
  67                         size = 0;
  68                         from -= subdev->size;
  69                         continue;
  70                 }
  71                 if (from + len > subdev->size)
  72                         /* First part goes into this subdev */
  73                         size = subdev->size - from;
  74                 else
  75                         /* Entire transaction goes into this subdev */
  76                         size = len;
  77
  78                 err = subdev->read(subdev, from, size, &retsize, buf);
  79
  80                 if (err)
  81                         break;
  82
  83                 *retlen += retsize;
  84                 len -= size;
  85                 if (len == 0)
  86                         break;
  87
  88                 err = -EINVAL;
  89                 buf += size;
  90                 from = 0;
  91         }
  92         return err;
  93 }
  94
  95 static int
  96 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
  97              size_t * retlen, const u_char * buf)
  98 {
  99         struct mtd_concat *concat = CONCAT(mtd);
 100         int err = -EINVAL;
 101         int i;
 102
 103         if (!(mtd->flags & MTD_WRITEABLE))
 104                 return -EROFS;
 105
 106         *retlen = 0;
 107
 108         for (i = 0; i < concat->num_subdev; i++) {
 109                 struct mtd_info *subdev = concat->subdev[i];
 110                 size_t size, retsize;
 111
 112                 if (to >= subdev->size) {
 113                         size = 0;
 114                         to -= subdev->size;
 115                         continue;
 116                 }
 117                 if (to + len > subdev->size)
 118                         size = subdev->size - to;
 119                 else
 120                         size = len;
 121
 122                 if (!(subdev->flags & MTD_WRITEABLE))
 123                         err = -EROFS;
 124                 else
 125                         err = subdev->write(subdev, to, size, &retsize, buf);
 126
 127                 if (err)
 128                         break;
 129
 130                 *retlen += retsize;
 131                 len -= size;
 132                 if (len == 0)
 133                         break;
 134
 135                 err = -EINVAL;
 136                 buf += size;
 137                 to = 0;
 138         }
 139         return err;
 140 }
 141
 142 static int
 143 concat_read_ecc(struct mtd_info *mtd, loff_t from, size_t len,
 144                 size_t * retlen, u_char * buf, u_char * eccbuf,
 145                 struct nand_oobinfo *oobsel)
 146 {
 147         struct mtd_concat *concat = CONCAT(mtd);
 148         int err = -EINVAL;
 149         int i;
 150
 151         *retlen = 0;
 152
 153         for (i = 0; i < concat->num_subdev; i++) {
 154                 struct mtd_info *subdev = concat->subdev[i];
 155                 size_t size, retsize;
 156
 157                 if (from >= subdev->size) {
 158                         /* Not destined for this subdev */
 159                         size = 0;
 160                         from -= subdev->size;
 161                         continue;
 162                 }
 163
 164                 if (from + len > subdev->size)
 165                         /* First part goes into this subdev */
 166                         size = subdev->size - from;
 167                 else
 168                         /* Entire transaction goes into this subdev */
 169                         size = len;
 170
 171                 if (subdev->read_ecc)
 172                         err = subdev->read_ecc(subdev, from, size,
 173                                                &retsize, buf, eccbuf, oobsel);
 174                 else
 175                         err = -EINVAL;
 176
 177                 if (err)
 178                         break;
 179
 180                 *retlen += retsize;
 181                 len -= size;
 182                 if (len == 0)
 183                         break;
 184
 185                 err = -EINVAL;
 186                 buf += size;
 187                 if (eccbuf) {
 188                         eccbuf += subdev->oobsize;
 189                         /* in nand.c at least, eccbufs are
 190                            tagged with 2 (int)eccstatus'; we
 191                            must account for these */
 192                         eccbuf += 2 * (sizeof (int));
 193                 }
 194                 from = 0;
 195         }
 196         return err;
 197 }
 198
 199 static int
 200 concat_write_ecc(struct mtd_info *mtd, loff_t to, size_t len,
 201                  size_t * retlen, const u_char * buf, u_char * eccbuf,
 202                  struct nand_oobinfo *oobsel)
 203 {
 204         struct mtd_concat *concat = CONCAT(mtd);
 205         int err = -EINVAL;
 206         int i;
 207
 208         if (!(mtd->flags & MTD_WRITEABLE))
 209                 return -EROFS;
 210
 211         *retlen = 0;
 212
 213         for (i = 0; i < concat->num_subdev; i++) {
 214                 struct mtd_info *subdev = concat->subdev[i];
 215                 size_t size, retsize;
 216
 217                 if (to >= subdev->size) {
 218                         size = 0;
 219                         to -= subdev->size;
 220                         continue;
 221                 }
 222                 if (to + len > subdev->size)
 223                         size = subdev->size - to;
 224                 else
 225                         size = len;
 226
 227                 if (!(subdev->flags & MTD_WRITEABLE))
 228                         err = -EROFS;
 229                 else if (subdev->write_ecc)
 230                         err = subdev->write_ecc(subdev, to, size,
 231                                                 &retsize, buf, eccbuf, oobsel);
 232                 else
 233                         err = -EINVAL;
 234
 235                 if (err)
 236                         break;
 237
 238                 *retlen += retsize;
 239                 len -= size;
 240                 if (len == 0)
 241                         break;
 242
 243                 err = -EINVAL;
 244                 buf += size;
 245                 if (eccbuf)
 246                         eccbuf += subdev->oobsize;
 247                 to = 0;
 248         }
 249         return err;
 250 }
 251
 252 static int
 253 concat_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
 254                 size_t * retlen, u_char * buf)
 255 {
 256         struct mtd_concat *concat = CONCAT(mtd);
 257         int err = -EINVAL;
 258         int i;
 259
 260         *retlen = 0;
 261
 262         for (i = 0; i < concat->num_subdev; i++) {
 263                 struct mtd_info *subdev = concat->subdev[i];
 264                 size_t size, retsize;
 265
 266                 if (from >= subdev->size) {
 267                         /* Not destined for this subdev */
 268                         size = 0;
 269                         from -= subdev->size;
 270                         continue;
 271                 }
 272                 if (from + len > subdev->size)
 273                         /* First part goes into this subdev */
 274                         size = subdev->size - from;
 275                 else
 276                         /* Entire transaction goes into this subdev */
 277                         size = len;
 278
 279                 if (subdev->read_oob)
 280                         err = subdev->read_oob(subdev, from, size,
 281                                                &retsize, buf);
 282                 else
 283                         err = -EINVAL;
 284
 285                 if (err)
 286                         break;
 287
 288                 *retlen += retsize;
 289                 len -= size;
 290                 if (len == 0)
 291                         break;
 292
 293                 err = -EINVAL;
 294                 buf += size;
 295                 from = 0;
 296         }
 297         return err;
 298 }
 299
 300 static int
 301 concat_write_oob(struct mtd_info *mtd, loff_t to, size_t len,
 302                  size_t * retlen, const u_char * buf)
 303 {
 304         struct mtd_concat *concat = CONCAT(mtd);
 305         int err = -EINVAL;
 306         int i;
 307
 308         if (!(mtd->flags & MTD_WRITEABLE))
 309                 return -EROFS;
 310
 311         *retlen = 0;
 312
 313         for (i = 0; i < concat->num_subdev; i++) {
 314                 struct mtd_info *subdev = concat->subdev[i];
 315                 size_t size, retsize;
 316
 317                 if (to >= subdev->size) {
 318                         size = 0;
 319                         to -= subdev->size;
 320                         continue;
 321                 }
 322                 if (to + len > subdev->size)
 323                         size = subdev->size - to;
 324                 else
 325                         size = len;
 326
 327                 if (!(subdev->flags & MTD_WRITEABLE))
 328                         err = -EROFS;
 329                 else if (subdev->write_oob)
 330                         err = subdev->write_oob(subdev, to, size, &retsize,
 331                                                 buf);
 332                 else
 333                         err = -EINVAL;
 334
 335                 if (err)
 336                         break;
 337
 338                 *retlen += retsize;
 339                 len -= size;
 340                 if (len == 0)
 341                         break;
 342
 343                 err = -EINVAL;
 344                 buf += size;
 345                 to = 0;
 346         }
 347         return err;
 348 }
 349
 350 static void concat_erase_callback(struct erase_info *instr)
 351 {
 352         wake_up((wait_queue_head_t *) instr->priv);
 353 }
 354
 355 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 356 {
 357         int err;
 358         wait_queue_head_t waitq;
 359         DECLARE_WAITQUEUE(wait, current);
 360
 361         /*
 362          * This code was stol^H^H^H^Hinspired by mtdchar.c
 363          */
 364         init_waitqueue_head(&waitq);
 365
 366         erase->mtd = mtd;
 367         erase->callback = concat_erase_callback;
 368         erase->priv = (unsigned long) &waitq;
 369
 370         /*
 371          * FIXME: Allow INTERRUPTIBLE. Which means
 372          * not having the wait_queue head on the stack.
 373          */
 374         err = mtd->erase(mtd, erase);
 375         if (!err) {
 376                 set_current_state(TASK_UNINTERRUPTIBLE);
 377                 add_wait_queue(&waitq, &wait);
 378                 if (erase->state != MTD_ERASE_DONE
 379                     && erase->state != MTD_ERASE_FAILED)
 380                         schedule();
 381                 remove_wait_queue(&waitq, &wait);
 382                 set_current_state(TASK_RUNNING);
 383
 384                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 385         }
 386         return err;
 387 }
 388
 389 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 390 {
 391         struct mtd_concat *concat = CONCAT(mtd);
 392         struct mtd_info *subdev;
 393         int i, err;
 394         u_int32_t length, offset = 0;
 395         struct erase_info *erase;
 396
 397         if (!(mtd->flags & MTD_WRITEABLE))
 398                 return -EROFS;
 399
 400         if (instr->addr > concat->mtd.size)
 401                 return -EINVAL;
 402
 403         if (instr->len + instr->addr > concat->mtd.size)
 404                 return -EINVAL;
 405
 406         /*
 407          * Check for proper erase block alignment of the to-be-erased area.
 408          * It is easier to do this based on the super device's erase
 409          * region info rather than looking at each particular sub-device
 410          * in turn.
 411          */
 412         if (!concat->mtd.numeraseregions) {
 413                 /* the easy case: device has uniform erase block size */
 414                 if (instr->addr & (concat->mtd.erasesize - 1))
 415                         return -EINVAL;
 416                 if (instr->len & (concat->mtd.erasesize - 1))
 417                         return -EINVAL;
 418         } else {
 419                 /* device has variable erase size */
 420                 struct mtd_erase_region_info *erase_regions =
 421                     concat->mtd.eraseregions;
 422
 423                 /*
 424                  * Find the erase region where the to-be-erased area begins:
 425                  */
 426                 for (i = 0; i < concat->mtd.numeraseregions &&
 427                      instr->addr >= erase_regions[i].offset; i++) ;
 428                 --i;
 429
 430                 /*
 431                  * Now erase_regions[i] is the region in which the
 432                  * to-be-erased area begins. Verify that the starting
 433                  * offset is aligned to this region's erase size:
 434                  */
 435                 if (instr->addr & (erase_regions[i].erasesize - 1))
 436                         return -EINVAL;
 437
 438                 /*
 439                  * now find the erase region where the to-be-erased area ends:
 440                  */
 441                 for (; i < concat->mtd.numeraseregions &&
 442                      (instr->addr + instr->len) >= erase_regions[i].offset;
 443                      ++i) ;
 444                 --i;
 445                 /*
 446                  * check if the ending offset is aligned to this region's erase size
 447                  */
 448                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 449                                                   1))
 450                         return -EINVAL;
 451         }
 452
 453         instr->fail_addr = 0xffffffff;
 454
 455         /* make a local copy of instr to avoid modifying the caller's struct */
 456         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 457
 458         if (!erase)
 459                 return -ENOMEM;
 460
 461         *erase = *instr;
 462         length = instr->len;
 463
 464         /*
 465          * find the subdevice where the to-be-erased area begins, adjust
 466          * starting offset to be relative to the subdevice start
 467          */
 468         for (i = 0; i < concat->num_subdev; i++) {
 469                 subdev = concat->subdev[i];
 470                 if (subdev->size <= erase->addr) {
 471                         erase->addr -= subdev->size;
 472                         offset += subdev->size;
 473                 } else {
 474                         break;
 475                 }
 476         }
 477
 478         /* must never happen since size limit has been verified above */
 479         if (i >= concat->num_subdev)
 480                 BUG();
 481
 482         /* now do the erase: */
 483         err = 0;
 484         for (; length > 0; i++) {
 485                 /* loop for all subdevices affected by this request */
 486                 subdev = concat->subdev[i];     /* get current subdevice */
 487
 488                 /* limit length to subdevice's size: */
 489                 if (erase->addr + length > subdev->size)
 490                         erase->len = subdev->size - erase->addr;
 491                 else
 492                         erase->len = length;
 493
 494                 if (!(subdev->flags & MTD_WRITEABLE)) {
 495                         err = -EROFS;
 496                         break;
 497                 }
 498                 length -= erase->len;
 499                 if ((err = concat_dev_erase(subdev, erase))) {
 500                         /* sanity check: should never happen since
 501                          * block alignment has been checked above */
 502                         if (err == -EINVAL)
 503                                 BUG();
 504                         if (erase->fail_addr != 0xffffffff)
 505                                 instr->fail_addr = erase->fail_addr + offset;
 506                         break;
 507                 }
 508                 /*
 509                  * erase->addr specifies the offset of the area to be
 510                  * erased *within the current subdevice*. It can be
 511                  * non-zero only the first time through this loop, i.e.
 512                  * for the first subdevice where blocks need to be erased.
 513                  * All the following erases must begin at the start of the
 514                  * current subdevice, i.e. at offset zero.
 515                  */
 516                 erase->addr = 0;
 517                 offset += subdev->size;
 518         }
 519         instr->state = erase->state;
 520         kfree(erase);
 521         if (err)
 522                 return err;
 523
 524         if (instr->callback)
 525                 instr->callback(instr);
 526         return 0;
 527 }
 528
 529 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
 530 {
 531         struct mtd_concat *concat = CONCAT(mtd);
 532         int i, err = -EINVAL;
 533
 534         if ((len + ofs) > mtd->size)
 535                 return -EINVAL;
 536
 537         for (i = 0; i < concat->num_subdev; i++) {
 538                 struct mtd_info *subdev = concat->subdev[i];
 539                 size_t size;
 540
 541                 if (ofs >= subdev->size) {
 542                         size = 0;
 543                         ofs -= subdev->size;
 544                         continue;
 545                 }
 546                 if (ofs + len > subdev->size)
 547                         size = subdev->size - ofs;
 548                 else
 549                         size = len;
 550
 551                 err = subdev->lock(subdev, ofs, size);
 552
 553                 if (err)
 554                         break;
 555
 556                 len -= size;
 557                 if (len == 0)
 558                         break;
 559
 560                 err = -EINVAL;
 561                 ofs = 0;
 562         }
 563
 564         return err;
 565 }
 566
 567 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
 568 {
 569         struct mtd_concat *concat = CONCAT(mtd);
 570         int i, err = 0;
 571
 572         if ((len + ofs) > mtd->size)
 573                 return -EINVAL;
 574
 575         for (i = 0; i < concat->num_subdev; i++) {
 576                 struct mtd_info *subdev = concat->subdev[i];
 577                 size_t size;
 578
 579                 if (ofs >= subdev->size) {
 580                         size = 0;
 581                         ofs -= subdev->size;
 582                         continue;
 583                 }
 584                 if (ofs + len > subdev->size)
 585                         size = subdev->size - ofs;
 586                 else
 587                         size = len;
 588
 589                 err = subdev->unlock(subdev, ofs, size);
 590
 591                 if (err)
 592                         break;
 593
 594                 len -= size;
 595                 if (len == 0)
 596                         break;
 597
 598                 err = -EINVAL;
 599                 ofs = 0;
 600         }
 601
 602         return err;
 603 }
 604
 605 static void concat_sync(struct mtd_info *mtd)
 606 {
 607         struct mtd_concat *concat = CONCAT(mtd);
 608         int i;
 609
 610         for (i = 0; i < concat->num_subdev; i++) {
 611                 struct mtd_info *subdev = concat->subdev[i];
 612                 subdev->sync(subdev);
 613         }
 614 }
 615
 616 static int concat_suspend(struct mtd_info *mtd)
 617 {
 618         struct mtd_concat *concat = CONCAT(mtd);
 619         int i, rc = 0;
 620
 621         for (i = 0; i < concat->num_subdev; i++) {
 622                 struct mtd_info *subdev = concat->subdev[i];
 623                 if ((rc = subdev->suspend(subdev)) < 0)
 624                         return rc;
 625         }
 626         return rc;
 627 }
 628
 629 static void concat_resume(struct mtd_info *mtd)
 630 {
 631         struct mtd_concat *concat = CONCAT(mtd);
 632         int i;
 633
 634         for (i = 0; i < concat->num_subdev; i++) {
 635                 struct mtd_info *subdev = concat->subdev[i];
 636                 subdev->resume(subdev);
 637         }
 638 }
 639
 640 /*
 641  * This function constructs a virtual MTD device by concatenating
 642  * num_devs MTD devices. A pointer to the new device object is
 643  * stored to *new_dev upon success. This function does _not_
 644  * register any devices: this is the caller's responsibility.
 645  */
 646 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 647                                    int num_devs,        /* number of subdevices      */
 648                                    char *name)
 649 {                               /* name for the new device   */
 650         int i;
 651         size_t size;
 652         struct mtd_concat *concat;
 653         u_int32_t max_erasesize, curr_erasesize;
 654         int num_erase_region;
 655
 656         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 657         for (i = 0; i < num_devs; i++)
 658                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 659         printk(KERN_NOTICE "into device \"%s\"\n", name);
 660
 661         /* allocate the device structure */
 662         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 663         concat = kmalloc(size, GFP_KERNEL);
 664         if (!concat) {
 665                 printk
 666                     ("memory allocation error while creating concatenated device \"%s\"\n",
 667                      name);
 668                 return NULL;
 669         }
 670         memset(concat, 0, size);
 671         concat->subdev = (struct mtd_info **) (concat + 1);
 672
 673         /*
 674          * Set up the new "super" device's MTD object structure, check for
 675          * incompatibilites between the subdevices.
 676          */
 677         concat->mtd.type = subdev[0]->type;
 678         concat->mtd.flags = subdev[0]->flags;
 679         concat->mtd.size = subdev[0]->size;
 680         concat->mtd.erasesize = subdev[0]->erasesize;
 681         concat->mtd.oobblock = subdev[0]->oobblock;
 682         concat->mtd.oobsize = subdev[0]->oobsize;
 683         concat->mtd.ecctype = subdev[0]->ecctype;
 684         concat->mtd.eccsize = subdev[0]->eccsize;
 685         if (subdev[0]->read_ecc)
 686                 concat->mtd.read_ecc = concat_read_ecc;
 687         if (subdev[0]->write_ecc)
 688                 concat->mtd.write_ecc = concat_write_ecc;
 689         if (subdev[0]->read_oob)
 690                 concat->mtd.read_oob = concat_read_oob;
 691         if (subdev[0]->write_oob)
 692                 concat->mtd.write_oob = concat_write_oob;
 693
 694         concat->subdev[0] = subdev[0];
 695
 696         for (i = 1; i < num_devs; i++) {
 697                 if (concat->mtd.type != subdev[i]->type) {
 698                         kfree(concat);
 699                         printk("Incompatible device type on \"%s\"\n",
 700                                subdev[i]->name);
 701                         return NULL;
 702                 }
 703                 if (concat->mtd.flags != subdev[i]->flags) {
 704                         /*
 705                          * Expect all flags except MTD_WRITEABLE to be
 706                          * equal on all subdevices.
 707                          */
 708                         if ((concat->mtd.flags ^ subdev[i]->
 709                              flags) & ~MTD_WRITEABLE) {
 710                                 kfree(concat);
 711                                 printk("Incompatible device flags on \"%s\"\n",
 712                                        subdev[i]->name);
 713                                 return NULL;
 714                         } else
 715                                 /* if writeable attribute differs,
 716                                    make super device writeable */
 717                                 concat->mtd.flags |=
 718                                     subdev[i]->flags & MTD_WRITEABLE;
 719                 }
 720                 concat->mtd.size += subdev[i]->size;
 721                 if (concat->mtd.oobblock   !=  subdev[i]->oobblock ||
 722                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 723                     concat->mtd.ecctype    !=  subdev[i]->ecctype ||
 724                     concat->mtd.eccsize    !=  subdev[i]->eccsize ||
 725                     !concat->mtd.read_ecc  != !subdev[i]->read_ecc ||
 726                     !concat->mtd.write_ecc != !subdev[i]->write_ecc ||
 727                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 728                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 729                         kfree(concat);
 730                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 731                                subdev[i]->name);
 732                         return NULL;
 733                 }
 734                 concat->subdev[i] = subdev[i];
 735
 736         }
 737
 738         concat->num_subdev = num_devs;
 739         concat->mtd.name = name;
 740
 741         /*
 742          * NOTE: for now, we do not provide any readv()/writev() methods
 743          *       because they are messy to implement and they are not
 744          *       used to a great extent anyway.
 745          */
 746         concat->mtd.erase = concat_erase;
 747         concat->mtd.read = concat_read;
 748         concat->mtd.write = concat_write;
 749         concat->mtd.sync = concat_sync;
 750         concat->mtd.lock = concat_lock;
 751         concat->mtd.unlock = concat_unlock;
 752         concat->mtd.suspend = concat_suspend;
 753         concat->mtd.resume = concat_resume;
 754
 755         /*
 756          * Combine the erase block size info of the subdevices:
 757          *
 758          * first, walk the map of the new device and see how
 759          * many changes in erase size we have
 760          */
 761         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 762         num_erase_region = 1;
 763         for (i = 0; i < num_devs; i++) {
 764                 if (subdev[i]->numeraseregions == 0) {
 765                         /* current subdevice has uniform erase size */
 766                         if (subdev[i]->erasesize != curr_erasesize) {
 767                                 /* if it differs from the last subdevice's erase size, count it */
 768                                 ++num_erase_region;
 769                                 curr_erasesize = subdev[i]->erasesize;
 770                                 if (curr_erasesize > max_erasesize)
 771                                         max_erasesize = curr_erasesize;
 772                         }
 773                 } else {
 774                         /* current subdevice has variable erase size */
 775                         int j;
 776                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 777
 778                                 /* walk the list of erase regions, count any changes */
 779                                 if (subdev[i]->eraseregions[j].erasesize !=
 780                                     curr_erasesize) {
 781                                         ++num_erase_region;
 782                                         curr_erasesize =
 783                                             subdev[i]->eraseregions[j].
 784                                             erasesize;
 785                                         if (curr_erasesize > max_erasesize)
 786                                                 max_erasesize = curr_erasesize;
 787                                 }
 788                         }
 789                 }
 790         }
 791
 792         if (num_erase_region == 1) {
 793                 /*
 794                  * All subdevices have the same uniform erase size.
 795                  * This is easy:
 796                  */
 797                 concat->mtd.erasesize = curr_erasesize;
 798                 concat->mtd.numeraseregions = 0;
 799         } else {
 800                 /*
 801                  * erase block size varies across the subdevices: allocate
 802                  * space to store the data describing the variable erase regions
 803                  */
 804                 struct mtd_erase_region_info *erase_region_p;
 805                 u_int32_t begin, position;
 806
 807                 concat->mtd.erasesize = max_erasesize;
 808                 concat->mtd.numeraseregions = num_erase_region;
 809                 concat->mtd.eraseregions = erase_region_p =
 810                     kmalloc(num_erase_region *
 811                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 812                 if (!erase_region_p) {
 813                         kfree(concat);
 814                         printk
 815                             ("memory allocation error while creating erase region list"
 816                              " for device \"%s\"\n", name);
 817                         return NULL;
 818                 }
 819
 820                 /*
 821                  * walk the map of the new device once more and fill in
 822                  * in erase region info:
 823                  */
 824                 curr_erasesize = subdev[0]->erasesize;
 825                 begin = position = 0;
 826                 for (i = 0; i < num_devs; i++) {
 827                         if (subdev[i]->numeraseregions == 0) {
 828                                 /* current subdevice has uniform erase size */
 829                                 if (subdev[i]->erasesize != curr_erasesize) {
 830                                         /*
 831                                          *  fill in an mtd_erase_region_info structure for the area
 832                                          *  we have walked so far:
 833                                          */
 834                                         erase_region_p->offset = begin;
 835                                         erase_region_p->erasesize =
 836                                             curr_erasesize;
 837                                         erase_region_p->numblocks =
 838                                             (position - begin) / curr_erasesize;
 839                                         begin = position;
 840
 841                                         curr_erasesize = subdev[i]->erasesize;
 842                                         ++erase_region_p;
 843                                 }
 844                                 position += subdev[i]->size;
 845                         } else {
 846                                 /* current subdevice has variable erase size */
 847                                 int j;
 848                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 849                                         /* walk the list of erase regions, count any changes */
 850                                         if (subdev[i]->eraseregions[j].
 851                                             erasesize != curr_erasesize) {
 852                                                 erase_region_p->offset = begin;
 853                                                 erase_region_p->erasesize =
 854                                                     curr_erasesize;
 855                                                 erase_region_p->numblocks =
 856                                                     (position -
 857                                                      begin) / curr_erasesize;
 858                                                 begin = position;
 859
 860                                                 curr_erasesize =
 861                                                     subdev[i]->eraseregions[j].
 862                                                     erasesize;
 863                                                 ++erase_region_p;
 864                                         }
 865                                         position +=
 866                                             subdev[i]->eraseregions[j].
 867                                             numblocks * curr_erasesize;
 868                                 }
 869                         }
 870                 }
 871                 /* Now write the final entry */
 872                 erase_region_p->offset = begin;
 873                 erase_region_p->erasesize = curr_erasesize;
 874                 erase_region_p->numblocks = (position - begin) / curr_erasesize;
 875         }
 876
 877         return &concat->mtd;
 878 }
 879
 880 /*
 881  * This function destroys an MTD object obtained from concat_mtd_devs()
 882  */
 883
 884 void mtd_concat_destroy(struct mtd_info *mtd)
 885 {
 886         struct mtd_concat *concat = CONCAT(mtd);
 887         if (concat->mtd.numeraseregions)
 888                 kfree(concat->mtd.eraseregions);
 889         kfree(concat);
 890 }
 891
 892 EXPORT_SYMBOL(mtd_concat_create);
 893 EXPORT_SYMBOL(mtd_concat_destroy);
 894
 895 MODULE_LICENSE("GPL");
 896 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 897 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");