drivers/mtd/mtdconcat.c

   1 /*
   2  * MTD device concatenation layer
   3  *
   4  * (C) 2002 Robert Kaiser <rkaiser@sysgo.de>
   5  *
   6  * NAND support by Christian Gan <cgan@iders.ca>
   7  *
   8  * This code is GPL
   9  *
  10  * $Id: mtdconcat.c,v 1.9 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 #if 1   // mask by Victor Yu. 05-14-2007
 377                 set_current_state(TASK_UNINTERRUPTIBLE);
 378 #endif
 379                 add_wait_queue(&waitq, &wait);
 380                 if (erase->state != MTD_ERASE_DONE
 381                     && erase->state != MTD_ERASE_FAILED)
 382                         schedule();
 383                 remove_wait_queue(&waitq, &wait);
 384 #if 1   // mask by Victor Yu. 05-14-2007
 385                 set_current_state(TASK_RUNNING);
 386 #endif
 387
 388                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 389         }
 390         return err;
 391 }
 392
 393 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 394 {
 395         struct mtd_concat *concat = CONCAT(mtd);
 396         struct mtd_info *subdev;
 397         int i, err;
 398         u_int32_t length, offset = 0;
 399         struct erase_info *erase;
 400
 401         if (!(mtd->flags & MTD_WRITEABLE))
 402                 return -EROFS;
 403
 404         if (instr->addr > concat->mtd.size)
 405                 return -EINVAL;
 406
 407         if (instr->len + instr->addr > concat->mtd.size)
 408                 return -EINVAL;
 409
 410         /*
 411          * Check for proper erase block alignment of the to-be-erased area.
 412          * It is easier to do this based on the super device's erase
 413          * region info rather than looking at each particular sub-device
 414          * in turn.
 415          */
 416         if (!concat->mtd.numeraseregions) {
 417                 /* the easy case: device has uniform erase block size */
 418                 if (instr->addr & (concat->mtd.erasesize - 1))
 419                         return -EINVAL;
 420                 if (instr->len & (concat->mtd.erasesize - 1))
 421                         return -EINVAL;
 422         } else {
 423                 /* device has variable erase size */
 424                 struct mtd_erase_region_info *erase_regions =
 425                     concat->mtd.eraseregions;
 426
 427                 /*
 428                  * Find the erase region where the to-be-erased area begins:
 429                  */
 430                 for (i = 0; i < concat->mtd.numeraseregions &&
 431                      instr->addr >= erase_regions[i].offset; i++) ;
 432                 --i;
 433
 434                 /*
 435                  * Now erase_regions[i] is the region in which the
 436                  * to-be-erased area begins. Verify that the starting
 437                  * offset is aligned to this region's erase size:
 438                  */
 439                 if (instr->addr & (erase_regions[i].erasesize - 1))
 440                         return -EINVAL;
 441
 442                 /*
 443                  * now find the erase region where the to-be-erased area ends:
 444                  */
 445                 for (; i < concat->mtd.numeraseregions &&
 446                      (instr->addr + instr->len) >= erase_regions[i].offset;
 447                      ++i) ;
 448                 --i;
 449                 /*
 450                  * check if the ending offset is aligned to this region's erase size
 451                  */
 452                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 453                                                   1))
 454                         return -EINVAL;
 455         }
 456
 457         instr->fail_addr = 0xffffffff;
 458
 459         /* make a local copy of instr to avoid modifying the caller's struct */
 460         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 461
 462         if (!erase)
 463                 return -ENOMEM;
 464
 465         *erase = *instr;
 466         length = instr->len;
 467
 468         /*
 469          * find the subdevice where the to-be-erased area begins, adjust
 470          * starting offset to be relative to the subdevice start
 471          */
 472         for (i = 0; i < concat->num_subdev; i++) {
 473                 subdev = concat->subdev[i];
 474                 if (subdev->size <= erase->addr) {
 475                         erase->addr -= subdev->size;
 476                         offset += subdev->size;
 477                 } else {
 478                         break;
 479                 }
 480         }
 481
 482         /* must never happen since size limit has been verified above */
 483         if (i >= concat->num_subdev)
 484                 BUG();
 485
 486         /* now do the erase: */
 487         err = 0;
 488         for (; length > 0; i++) {
 489                 /* loop for all subdevices affected by this request */
 490                 subdev = concat->subdev[i];     /* get current subdevice */
 491
 492                 /* limit length to subdevice's size: */
 493                 if (erase->addr + length > subdev->size)
 494                         erase->len = subdev->size - erase->addr;
 495                 else
 496                         erase->len = length;
 497
 498                 if (!(subdev->flags & MTD_WRITEABLE)) {
 499                         err = -EROFS;
 500                         break;
 501                 }
 502                 length -= erase->len;
 503                 if ((err = concat_dev_erase(subdev, erase))) {
 504                         /* sanity check: should never happen since
 505                          * block alignment has been checked above */
 506                         if (err == -EINVAL)
 507                                 BUG();
 508                         if (erase->fail_addr != 0xffffffff)
 509                                 instr->fail_addr = erase->fail_addr + offset;
 510                         break;
 511                 }
 512                 /*
 513                  * erase->addr specifies the offset of the area to be
 514                  * erased *within the current subdevice*. It can be
 515                  * non-zero only the first time through this loop, i.e.
 516                  * for the first subdevice where blocks need to be erased.
 517                  * All the following erases must begin at the start of the
 518                  * current subdevice, i.e. at offset zero.
 519                  */
 520                 erase->addr = 0;
 521                 offset += subdev->size;
 522         }
 523         instr->state = erase->state;
 524         kfree(erase);
 525         if (err)
 526                 return err;
 527
 528         if (instr->callback)
 529                 instr->callback(instr);
 530         return 0;
 531 }
 532
 533 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
 534 {
 535         struct mtd_concat *concat = CONCAT(mtd);
 536         int i, err = -EINVAL;
 537
 538         if ((len + ofs) > mtd->size)
 539                 return -EINVAL;
 540
 541         for (i = 0; i < concat->num_subdev; i++) {
 542                 struct mtd_info *subdev = concat->subdev[i];
 543                 size_t size;
 544
 545                 if (ofs >= subdev->size) {
 546                         size = 0;
 547                         ofs -= subdev->size;
 548                         continue;
 549                 }
 550                 if (ofs + len > subdev->size)
 551                         size = subdev->size - ofs;
 552                 else
 553                         size = len;
 554
 555                 err = subdev->lock(subdev, ofs, size);
 556
 557                 if (err)
 558                         break;
 559
 560                 len -= size;
 561                 if (len == 0)
 562                         break;
 563
 564                 err = -EINVAL;
 565                 ofs = 0;
 566         }
 567
 568         return err;
 569 }
 570
 571 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
 572 {
 573         struct mtd_concat *concat = CONCAT(mtd);
 574         int i, err = 0;
 575
 576         if ((len + ofs) > mtd->size)
 577                 return -EINVAL;
 578
 579         for (i = 0; i < concat->num_subdev; i++) {
 580                 struct mtd_info *subdev = concat->subdev[i];
 581                 size_t size;
 582
 583                 if (ofs >= subdev->size) {
 584                         size = 0;
 585                         ofs -= subdev->size;
 586                         continue;
 587                 }
 588                 if (ofs + len > subdev->size)
 589                         size = subdev->size - ofs;
 590                 else
 591                         size = len;
 592
 593                 err = subdev->unlock(subdev, ofs, size);
 594
 595                 if (err)
 596                         break;
 597
 598                 len -= size;
 599                 if (len == 0)
 600                         break;
 601
 602                 err = -EINVAL;
 603                 ofs = 0;
 604         }
 605
 606         return err;
 607 }
 608
 609 static void concat_sync(struct mtd_info *mtd)
 610 {
 611         struct mtd_concat *concat = CONCAT(mtd);
 612         int i;
 613
 614         for (i = 0; i < concat->num_subdev; i++) {
 615                 struct mtd_info *subdev = concat->subdev[i];
 616                 subdev->sync(subdev);
 617         }
 618 }
 619
 620 static int concat_suspend(struct mtd_info *mtd)
 621 {
 622         struct mtd_concat *concat = CONCAT(mtd);
 623         int i, rc = 0;
 624
 625         for (i = 0; i < concat->num_subdev; i++) {
 626                 struct mtd_info *subdev = concat->subdev[i];
 627                 if ((rc = subdev->suspend(subdev)) < 0)
 628                         return rc;
 629         }
 630         return rc;
 631 }
 632
 633 static void concat_resume(struct mtd_info *mtd)
 634 {
 635         struct mtd_concat *concat = CONCAT(mtd);
 636         int i;
 637
 638         for (i = 0; i < concat->num_subdev; i++) {
 639                 struct mtd_info *subdev = concat->subdev[i];
 640                 subdev->resume(subdev);
 641         }
 642 }
 643
 644 /*
 645  * This function constructs a virtual MTD device by concatenating
 646  * num_devs MTD devices. A pointer to the new device object is
 647  * stored to *new_dev upon success. This function does _not_
 648  * register any devices: this is the caller's responsibility.
 649  */
 650 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 651                                    int num_devs,        /* number of subdevices      */
 652                                    char *name)
 653 {                               /* name for the new device   */
 654         int i;
 655         size_t size;
 656         struct mtd_concat *concat;
 657         u_int32_t max_erasesize, curr_erasesize;
 658         int num_erase_region;
 659
 660         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 661         for (i = 0; i < num_devs; i++)
 662                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 663         printk(KERN_NOTICE "into device \"%s\"\n", name);
 664
 665         /* allocate the device structure */
 666         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 667         concat = kmalloc(size, GFP_KERNEL);
 668         if (!concat) {
 669                 printk
 670                     ("memory allocation error while creating concatenated device \"%s\"\n",
 671                      name);
 672                 return NULL;
 673         }
 674         memset(concat, 0, size);
 675         concat->subdev = (struct mtd_info **) (concat + 1);
 676
 677         /*
 678          * Set up the new "super" device's MTD object structure, check for
 679          * incompatibilites between the subdevices.
 680          */
 681         concat->mtd.type = subdev[0]->type;
 682         concat->mtd.flags = subdev[0]->flags;
 683         concat->mtd.size = subdev[0]->size;
 684         concat->mtd.erasesize = subdev[0]->erasesize;
 685         concat->mtd.oobblock = subdev[0]->oobblock;
 686         concat->mtd.oobsize = subdev[0]->oobsize;
 687         concat->mtd.ecctype = subdev[0]->ecctype;
 688         concat->mtd.eccsize = subdev[0]->eccsize;
 689         if (subdev[0]->read_ecc)
 690                 concat->mtd.read_ecc = concat_read_ecc;
 691         if (subdev[0]->write_ecc)
 692                 concat->mtd.write_ecc = concat_write_ecc;
 693         if (subdev[0]->read_oob)
 694                 concat->mtd.read_oob = concat_read_oob;
 695         if (subdev[0]->write_oob)
 696                 concat->mtd.write_oob = concat_write_oob;
 697
 698         concat->subdev[0] = subdev[0];
 699
 700         for (i = 1; i < num_devs; i++) {
 701                 if (concat->mtd.type != subdev[i]->type) {
 702                         kfree(concat);
 703                         printk("Incompatible device type on \"%s\"\n",
 704                                subdev[i]->name);
 705                         return NULL;
 706                 }
 707                 if (concat->mtd.flags != subdev[i]->flags) {
 708                         /*
 709                          * Expect all flags except MTD_WRITEABLE to be
 710                          * equal on all subdevices.
 711                          */
 712                         if ((concat->mtd.flags ^ subdev[i]->
 713                              flags) & ~MTD_WRITEABLE) {
 714                                 kfree(concat);
 715                                 printk("Incompatible device flags on \"%s\"\n",
 716                                        subdev[i]->name);
 717                                 return NULL;
 718                         } else
 719                                 /* if writeable attribute differs,
 720                                    make super device writeable */
 721                                 concat->mtd.flags |=
 722                                     subdev[i]->flags & MTD_WRITEABLE;
 723                 }
 724                 concat->mtd.size += subdev[i]->size;
 725                 if (concat->mtd.oobblock   !=  subdev[i]->oobblock ||
 726                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 727                     concat->mtd.ecctype    !=  subdev[i]->ecctype ||
 728                     concat->mtd.eccsize    !=  subdev[i]->eccsize ||
 729                     !concat->mtd.read_ecc  != !subdev[i]->read_ecc ||
 730                     !concat->mtd.write_ecc != !subdev[i]->write_ecc ||
 731                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 732                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 733                         kfree(concat);
 734                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 735                                subdev[i]->name);
 736                         return NULL;
 737                 }
 738                 concat->subdev[i] = subdev[i];
 739
 740         }
 741
 742         concat->num_subdev = num_devs;
 743         concat->mtd.name = name;
 744
 745         /*
 746          * NOTE: for now, we do not provide any readv()/writev() methods
 747          *       because they are messy to implement and they are not
 748          *       used to a great extent anyway.
 749          */
 750         concat->mtd.erase = concat_erase;
 751         concat->mtd.read = concat_read;
 752         concat->mtd.write = concat_write;
 753         concat->mtd.sync = concat_sync;
 754         concat->mtd.lock = concat_lock;
 755         concat->mtd.unlock = concat_unlock;
 756         concat->mtd.suspend = concat_suspend;
 757         concat->mtd.resume = concat_resume;
 758
 759         /*
 760          * Combine the erase block size info of the subdevices:
 761          *
 762          * first, walk the map of the new device and see how
 763          * many changes in erase size we have
 764          */
 765         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 766         num_erase_region = 1;
 767         for (i = 0; i < num_devs; i++) {
 768                 if (subdev[i]->numeraseregions == 0) {
 769                         /* current subdevice has uniform erase size */
 770                         if (subdev[i]->erasesize != curr_erasesize) {
 771                                 /* if it differs from the last subdevice's erase size, count it */
 772                                 ++num_erase_region;
 773                                 curr_erasesize = subdev[i]->erasesize;
 774                                 if (curr_erasesize > max_erasesize)
 775                                         max_erasesize = curr_erasesize;
 776                         }
 777                 } else {
 778                         /* current subdevice has variable erase size */
 779                         int j;
 780                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 781
 782                                 /* walk the list of erase regions, count any changes */
 783                                 if (subdev[i]->eraseregions[j].erasesize !=
 784                                     curr_erasesize) {
 785                                         ++num_erase_region;
 786                                         curr_erasesize =
 787                                             subdev[i]->eraseregions[j].
 788                                             erasesize;
 789                                         if (curr_erasesize > max_erasesize)
 790                                                 max_erasesize = curr_erasesize;
 791                                 }
 792                         }
 793                 }
 794         }
 795
 796         if (num_erase_region == 1) {
 797                 /*
 798                  * All subdevices have the same uniform erase size.
 799                  * This is easy:
 800                  */
 801                 concat->mtd.erasesize = curr_erasesize;
 802                 concat->mtd.numeraseregions = 0;
 803         } else {
 804                 /*
 805                  * erase block size varies across the subdevices: allocate
 806                  * space to store the data describing the variable erase regions
 807                  */
 808                 struct mtd_erase_region_info *erase_region_p;
 809                 u_int32_t begin, position;
 810
 811                 concat->mtd.erasesize = max_erasesize;
 812                 concat->mtd.numeraseregions = num_erase_region;
 813                 concat->mtd.eraseregions = erase_region_p =
 814                     kmalloc(num_erase_region *
 815                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 816                 if (!erase_region_p) {
 817                         kfree(concat);
 818                         printk
 819                             ("memory allocation error while creating erase region list"
 820                              " for device \"%s\"\n", name);
 821                         return NULL;
 822                 }
 823
 824                 /*
 825                  * walk the map of the new device once more and fill in
 826                  * in erase region info:
 827                  */
 828                 curr_erasesize = subdev[0]->erasesize;
 829                 begin = position = 0;
 830                 for (i = 0; i < num_devs; i++) {
 831                         if (subdev[i]->numeraseregions == 0) {
 832                                 /* current subdevice has uniform erase size */
 833                                 if (subdev[i]->erasesize != curr_erasesize) {
 834                                         /*
 835                                          *  fill in an mtd_erase_region_info structure for the area
 836                                          *  we have walked so far:
 837                                          */
 838                                         erase_region_p->offset = begin;
 839                                         erase_region_p->erasesize =
 840                                             curr_erasesize;
 841                                         erase_region_p->numblocks =
 842                                             (position - begin) / curr_erasesize;
 843                                         begin = position;
 844
 845                                         curr_erasesize = subdev[i]->erasesize;
 846                                         ++erase_region_p;
 847                                 }
 848                                 position += subdev[i]->size;
 849                         } else {
 850                                 /* current subdevice has variable erase size */
 851                                 int j;
 852                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 853                                         /* walk the list of erase regions, count any changes */
 854                                         if (subdev[i]->eraseregions[j].
 855                                             erasesize != curr_erasesize) {
 856                                                 erase_region_p->offset = begin;
 857                                                 erase_region_p->erasesize =
 858                                                     curr_erasesize;
 859                                                 erase_region_p->numblocks =
 860                                                     (position -
 861                                                      begin) / curr_erasesize;
 862                                                 begin = position;
 863
 864                                                 curr_erasesize =
 865                                                     subdev[i]->eraseregions[j].
 866                                                     erasesize;
 867                                                 ++erase_region_p;
 868                                         }
 869                                         position +=
 870                                             subdev[i]->eraseregions[j].
 871                                             numblocks * curr_erasesize;
 872                                 }
 873                         }
 874                 }
 875                 /* Now write the final entry */
 876                 erase_region_p->offset = begin;
 877                 erase_region_p->erasesize = curr_erasesize;
 878                 erase_region_p->numblocks = (position - begin) / curr_erasesize;
 879         }
 880
 881         return &concat->mtd;
 882 }
 883
 884 /*
 885  * This function destroys an MTD object obtained from concat_mtd_devs()
 886  */
 887
 888 void mtd_concat_destroy(struct mtd_info *mtd)
 889 {
 890         struct mtd_concat *concat = CONCAT(mtd);
 891         if (concat->mtd.numeraseregions)
 892                 kfree(concat->mtd.eraseregions);
 893         kfree(concat);
 894 }
 895
 896 EXPORT_SYMBOL(mtd_concat_create);
 897 EXPORT_SYMBOL(mtd_concat_destroy);
 898
 899 MODULE_LICENSE("GPL");
 900 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 901 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");