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/mtd/mtd.h>
  12 #include <linux/mtd/compat.h>
  13 #include <linux/mtd/concat.h>
  14 #include <ubi_uboot.h>
  15
  16 /*
  17  * Our storage structure:
  18  * Subdev points to an array of pointers to struct mtd_info objects
  19  * which is allocated along with this structure
  20  *
  21  */
  22 struct mtd_concat {
  23         struct mtd_info mtd;
  24         int num_subdev;
  25         struct mtd_info **subdev;
  26 };
  27
  28 /*
  29  * how to calculate the size required for the above structure,
  30  * including the pointer array subdev points to:
  31  */
  32 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  33         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  34
  35 /*
  36  * Given a pointer to the MTD object in the mtd_concat structure,
  37  * we can retrieve the pointer to that structure with this macro.
  38  */
  39 #define CONCAT(x)  ((struct mtd_concat *)(x))
  40
  41 /*
  42  * MTD methods which look up the relevant subdevice, translate the
  43  * effective address and pass through to the subdevice.
  44  */
  45
  46 static int
  47 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  48             size_t * retlen, u_char * buf)
  49 {
  50         struct mtd_concat *concat = CONCAT(mtd);
  51         int ret = 0, err;
  52         int i;
  53
  54         *retlen = 0;
  55
  56         for (i = 0; i < concat->num_subdev; i++) {
  57                 struct mtd_info *subdev = concat->subdev[i];
  58                 size_t size, retsize;
  59
  60                 if (from >= subdev->size) {
  61                         /* Not destined for this subdev */
  62                         size = 0;
  63                         from -= subdev->size;
  64                         continue;
  65                 }
  66                 if (from + len > subdev->size)
  67                         /* First part goes into this subdev */
  68                         size = subdev->size - from;
  69                 else
  70                         /* Entire transaction goes into this subdev */
  71                         size = len;
  72
  73                 err = subdev->read(subdev, from, size, &retsize, buf);
  74
  75                 /* Save information about bitflips! */
  76                 if (unlikely(err)) {
  77                         if (err == -EBADMSG) {
  78                                 mtd->ecc_stats.failed++;
  79                                 ret = err;
  80                         } else if (err == -EUCLEAN) {
  81                                 mtd->ecc_stats.corrected++;
  82                                 /* Do not overwrite -EBADMSG !! */
  83                                 if (!ret)
  84                                         ret = err;
  85                         } else
  86                                 return err;
  87                 }
  88
  89                 *retlen += retsize;
  90                 len -= size;
  91                 if (len == 0)
  92                         return ret;
  93
  94                 buf += size;
  95                 from = 0;
  96         }
  97         return -EINVAL;
  98 }
  99
 100 static int
 101 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 102              size_t * retlen, const u_char * buf)
 103 {
 104         struct mtd_concat *concat = CONCAT(mtd);
 105         int err = -EINVAL;
 106         int i;
 107
 108         if (!(mtd->flags & MTD_WRITEABLE))
 109                 return -EROFS;
 110
 111         *retlen = 0;
 112
 113         for (i = 0; i < concat->num_subdev; i++) {
 114                 struct mtd_info *subdev = concat->subdev[i];
 115                 size_t size, retsize;
 116
 117                 if (to >= subdev->size) {
 118                         size = 0;
 119                         to -= subdev->size;
 120                         continue;
 121                 }
 122                 if (to + len > subdev->size)
 123                         size = subdev->size - to;
 124                 else
 125                         size = len;
 126
 127                 if (!(subdev->flags & MTD_WRITEABLE))
 128                         err = -EROFS;
 129                 else
 130                         err = subdev->write(subdev, to, size, &retsize, buf);
 131
 132                 if (err)
 133                         break;
 134
 135                 *retlen += retsize;
 136                 len -= size;
 137                 if (len == 0)
 138                         break;
 139
 140                 err = -EINVAL;
 141                 buf += size;
 142                 to = 0;
 143         }
 144         return err;
 145 }
 146
 147 static int
 148 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 149 {
 150         struct mtd_concat *concat = CONCAT(mtd);
 151         struct mtd_oob_ops devops = *ops;
 152         int i, err, ret = 0;
 153
 154         ops->retlen = ops->oobretlen = 0;
 155
 156         for (i = 0; i < concat->num_subdev; i++) {
 157                 struct mtd_info *subdev = concat->subdev[i];
 158
 159                 if (from >= subdev->size) {
 160                         from -= subdev->size;
 161                         continue;
 162                 }
 163
 164                 /* partial read ? */
 165                 if (from + devops.len > subdev->size)
 166                         devops.len = subdev->size - from;
 167
 168                 err = subdev->read_oob(subdev, from, &devops);
 169                 ops->retlen += devops.retlen;
 170                 ops->oobretlen += devops.oobretlen;
 171
 172                 /* Save information about bitflips! */
 173                 if (unlikely(err)) {
 174                         if (err == -EBADMSG) {
 175                                 mtd->ecc_stats.failed++;
 176                                 ret = err;
 177                         } else if (err == -EUCLEAN) {
 178                                 mtd->ecc_stats.corrected++;
 179                                 /* Do not overwrite -EBADMSG !! */
 180                                 if (!ret)
 181                                         ret = err;
 182                         } else
 183                                 return err;
 184                 }
 185
 186                 if (devops.datbuf) {
 187                         devops.len = ops->len - ops->retlen;
 188                         if (!devops.len)
 189                                 return ret;
 190                         devops.datbuf += devops.retlen;
 191                 }
 192                 if (devops.oobbuf) {
 193                         devops.ooblen = ops->ooblen - ops->oobretlen;
 194                         if (!devops.ooblen)
 195                                 return ret;
 196                         devops.oobbuf += ops->oobretlen;
 197                 }
 198
 199                 from = 0;
 200         }
 201         return -EINVAL;
 202 }
 203
 204 static int
 205 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 206 {
 207         struct mtd_concat *concat = CONCAT(mtd);
 208         struct mtd_oob_ops devops = *ops;
 209         int i, err;
 210
 211         if (!(mtd->flags & MTD_WRITEABLE))
 212                 return -EROFS;
 213
 214         ops->retlen = 0;
 215
 216         for (i = 0; i < concat->num_subdev; i++) {
 217                 struct mtd_info *subdev = concat->subdev[i];
 218
 219                 if (to >= subdev->size) {
 220                         to -= subdev->size;
 221                         continue;
 222                 }
 223
 224                 /* partial write ? */
 225                 if (to + devops.len > subdev->size)
 226                         devops.len = subdev->size - to;
 227
 228                 err = subdev->write_oob(subdev, to, &devops);
 229                 ops->retlen += devops.retlen;
 230                 if (err)
 231                         return err;
 232
 233                 if (devops.datbuf) {
 234                         devops.len = ops->len - ops->retlen;
 235                         if (!devops.len)
 236                                 return 0;
 237                         devops.datbuf += devops.retlen;
 238                 }
 239                 if (devops.oobbuf) {
 240                         devops.ooblen = ops->ooblen - ops->oobretlen;
 241                         if (!devops.ooblen)
 242                                 return 0;
 243                         devops.oobbuf += devops.oobretlen;
 244                 }
 245                 to = 0;
 246         }
 247         return -EINVAL;
 248 }
 249
 250 static void concat_erase_callback(struct erase_info *instr)
 251 {
 252         /* Nothing to do here in U-Boot */
 253 }
 254
 255 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 256 {
 257         int err;
 258         wait_queue_head_t waitq;
 259         DECLARE_WAITQUEUE(wait, current);
 260
 261         /*
 262          * This code was stol^H^H^H^Hinspired by mtdchar.c
 263          */
 264         init_waitqueue_head(&waitq);
 265
 266         erase->mtd = mtd;
 267         erase->callback = concat_erase_callback;
 268         erase->priv = (unsigned long) &waitq;
 269
 270         /*
 271          * FIXME: Allow INTERRUPTIBLE. Which means
 272          * not having the wait_queue head on the stack.
 273          */
 274         err = mtd->erase(mtd, erase);
 275         if (!err) {
 276                 set_current_state(TASK_UNINTERRUPTIBLE);
 277                 add_wait_queue(&waitq, &wait);
 278                 if (erase->state != MTD_ERASE_DONE
 279                     && erase->state != MTD_ERASE_FAILED)
 280                         schedule();
 281                 remove_wait_queue(&waitq, &wait);
 282                 set_current_state(TASK_RUNNING);
 283
 284                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 285         }
 286         return err;
 287 }
 288
 289 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 290 {
 291         struct mtd_concat *concat = CONCAT(mtd);
 292         struct mtd_info *subdev;
 293         int i, err;
 294         uint64_t length, offset = 0;
 295         struct erase_info *erase;
 296
 297         if (!(mtd->flags & MTD_WRITEABLE))
 298                 return -EROFS;
 299
 300         if (instr->addr > concat->mtd.size)
 301                 return -EINVAL;
 302
 303         if (instr->len + instr->addr > concat->mtd.size)
 304                 return -EINVAL;
 305
 306         /*
 307          * Check for proper erase block alignment of the to-be-erased area.
 308          * It is easier to do this based on the super device's erase
 309          * region info rather than looking at each particular sub-device
 310          * in turn.
 311          */
 312         if (!concat->mtd.numeraseregions) {
 313                 /* the easy case: device has uniform erase block size */
 314                 if (instr->addr & (concat->mtd.erasesize - 1))
 315                         return -EINVAL;
 316                 if (instr->len & (concat->mtd.erasesize - 1))
 317                         return -EINVAL;
 318         } else {
 319                 /* device has variable erase size */
 320                 struct mtd_erase_region_info *erase_regions =
 321                     concat->mtd.eraseregions;
 322
 323                 /*
 324                  * Find the erase region where the to-be-erased area begins:
 325                  */
 326                 for (i = 0; i < concat->mtd.numeraseregions &&
 327                      instr->addr >= erase_regions[i].offset; i++) ;
 328                 --i;
 329
 330                 /*
 331                  * Now erase_regions[i] is the region in which the
 332                  * to-be-erased area begins. Verify that the starting
 333                  * offset is aligned to this region's erase size:
 334                  */
 335                 if (instr->addr & (erase_regions[i].erasesize - 1))
 336                         return -EINVAL;
 337
 338                 /*
 339                  * now find the erase region where the to-be-erased area ends:
 340                  */
 341                 for (; i < concat->mtd.numeraseregions &&
 342                      (instr->addr + instr->len) >= erase_regions[i].offset;
 343                      ++i) ;
 344                 --i;
 345                 /*
 346                  * check if the ending offset is aligned to this region's erase size
 347                  */
 348                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
 349                                                   1))
 350                         return -EINVAL;
 351         }
 352
 353         instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
 354
 355         /* make a local copy of instr to avoid modifying the caller's struct */
 356         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 357
 358         if (!erase)
 359                 return -ENOMEM;
 360
 361         *erase = *instr;
 362         length = instr->len;
 363
 364         /*
 365          * find the subdevice where the to-be-erased area begins, adjust
 366          * starting offset to be relative to the subdevice start
 367          */
 368         for (i = 0; i < concat->num_subdev; i++) {
 369                 subdev = concat->subdev[i];
 370                 if (subdev->size <= erase->addr) {
 371                         erase->addr -= subdev->size;
 372                         offset += subdev->size;
 373                 } else {
 374                         break;
 375                 }
 376         }
 377
 378         /* must never happen since size limit has been verified above */
 379         BUG_ON(i >= concat->num_subdev);
 380
 381         /* now do the erase: */
 382         err = 0;
 383         for (; length > 0; i++) {
 384                 /* loop for all subdevices affected by this request */
 385                 subdev = concat->subdev[i];     /* get current subdevice */
 386
 387                 /* limit length to subdevice's size: */
 388                 if (erase->addr + length > subdev->size)
 389                         erase->len = subdev->size - erase->addr;
 390                 else
 391                         erase->len = length;
 392
 393                 if (!(subdev->flags & MTD_WRITEABLE)) {
 394                         err = -EROFS;
 395                         break;
 396                 }
 397                 length -= erase->len;
 398                 if ((err = concat_dev_erase(subdev, erase))) {
 399                         /* sanity check: should never happen since
 400                          * block alignment has been checked above */
 401                         BUG_ON(err == -EINVAL);
 402                         if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
 403                                 instr->fail_addr = erase->fail_addr + offset;
 404                         break;
 405                 }
 406                 /*
 407                  * erase->addr specifies the offset of the area to be
 408                  * erased *within the current subdevice*. It can be
 409                  * non-zero only the first time through this loop, i.e.
 410                  * for the first subdevice where blocks need to be erased.
 411                  * All the following erases must begin at the start of the
 412                  * current subdevice, i.e. at offset zero.
 413                  */
 414                 erase->addr = 0;
 415                 offset += subdev->size;
 416         }
 417         instr->state = erase->state;
 418         kfree(erase);
 419         if (err)
 420                 return err;
 421
 422         if (instr->callback)
 423                 instr->callback(instr);
 424         return 0;
 425 }
 426
 427 static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 428 {
 429         struct mtd_concat *concat = CONCAT(mtd);
 430         int i, err = -EINVAL;
 431
 432         if ((len + ofs) > mtd->size)
 433                 return -EINVAL;
 434
 435         for (i = 0; i < concat->num_subdev; i++) {
 436                 struct mtd_info *subdev = concat->subdev[i];
 437                 uint64_t size;
 438
 439                 if (ofs >= subdev->size) {
 440                         size = 0;
 441                         ofs -= subdev->size;
 442                         continue;
 443                 }
 444                 if (ofs + len > subdev->size)
 445                         size = subdev->size - ofs;
 446                 else
 447                         size = len;
 448
 449                 err = subdev->lock(subdev, ofs, size);
 450
 451                 if (err)
 452                         break;
 453
 454                 len -= size;
 455                 if (len == 0)
 456                         break;
 457
 458                 err = -EINVAL;
 459                 ofs = 0;
 460         }
 461
 462         return err;
 463 }
 464
 465 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 466 {
 467         struct mtd_concat *concat = CONCAT(mtd);
 468         int i, err = 0;
 469
 470         if ((len + ofs) > mtd->size)
 471                 return -EINVAL;
 472
 473         for (i = 0; i < concat->num_subdev; i++) {
 474                 struct mtd_info *subdev = concat->subdev[i];
 475                 uint64_t size;
 476
 477                 if (ofs >= subdev->size) {
 478                         size = 0;
 479                         ofs -= subdev->size;
 480                         continue;
 481                 }
 482                 if (ofs + len > subdev->size)
 483                         size = subdev->size - ofs;
 484                 else
 485                         size = len;
 486
 487                 err = subdev->unlock(subdev, ofs, size);
 488
 489                 if (err)
 490                         break;
 491
 492                 len -= size;
 493                 if (len == 0)
 494                         break;
 495
 496                 err = -EINVAL;
 497                 ofs = 0;
 498         }
 499
 500         return err;
 501 }
 502
 503 static void concat_sync(struct mtd_info *mtd)
 504 {
 505         struct mtd_concat *concat = CONCAT(mtd);
 506         int i;
 507
 508         for (i = 0; i < concat->num_subdev; i++) {
 509                 struct mtd_info *subdev = concat->subdev[i];
 510                 subdev->sync(subdev);
 511         }
 512 }
 513
 514 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 515 {
 516         struct mtd_concat *concat = CONCAT(mtd);
 517         int i, res = 0;
 518
 519         if (!concat->subdev[0]->block_isbad)
 520                 return res;
 521
 522         if (ofs > mtd->size)
 523                 return -EINVAL;
 524
 525         for (i = 0; i < concat->num_subdev; i++) {
 526                 struct mtd_info *subdev = concat->subdev[i];
 527
 528                 if (ofs >= subdev->size) {
 529                         ofs -= subdev->size;
 530                         continue;
 531                 }
 532
 533                 res = subdev->block_isbad(subdev, ofs);
 534                 break;
 535         }
 536
 537         return res;
 538 }
 539
 540 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 541 {
 542         struct mtd_concat *concat = CONCAT(mtd);
 543         int i, err = -EINVAL;
 544
 545         if (!concat->subdev[0]->block_markbad)
 546                 return 0;
 547
 548         if (ofs > mtd->size)
 549                 return -EINVAL;
 550
 551         for (i = 0; i < concat->num_subdev; i++) {
 552                 struct mtd_info *subdev = concat->subdev[i];
 553
 554                 if (ofs >= subdev->size) {
 555                         ofs -= subdev->size;
 556                         continue;
 557                 }
 558
 559                 err = subdev->block_markbad(subdev, ofs);
 560                 if (!err)
 561                         mtd->ecc_stats.badblocks++;
 562                 break;
 563         }
 564
 565         return err;
 566 }
 567
 568 /*
 569  * This function constructs a virtual MTD device by concatenating
 570  * num_devs MTD devices. A pointer to the new device object is
 571  * stored to *new_dev upon success. This function does _not_
 572  * register any devices: this is the caller's responsibility.
 573  */
 574 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 575                                    int num_devs,        /* number of subdevices      */
 576                                    const char *name)
 577 {                               /* name for the new device   */
 578         int i;
 579         size_t size;
 580         struct mtd_concat *concat;
 581         uint32_t max_erasesize, curr_erasesize;
 582         int num_erase_region;
 583
 584         debug("Concatenating MTD devices:\n");
 585         for (i = 0; i < num_devs; i++)
 586                 debug("(%d): \"%s\"\n", i, subdev[i]->name);
 587         debug("into device \"%s\"\n", name);
 588
 589         /* allocate the device structure */
 590         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 591         concat = kzalloc(size, GFP_KERNEL);
 592         if (!concat) {
 593                 printk
 594                     ("memory allocation error while creating concatenated device \"%s\"\n",
 595                      name);
 596                 return NULL;
 597         }
 598         concat->subdev = (struct mtd_info **) (concat + 1);
 599
 600         /*
 601          * Set up the new "super" device's MTD object structure, check for
 602          * incompatibilites between the subdevices.
 603          */
 604         concat->mtd.type = subdev[0]->type;
 605         concat->mtd.flags = subdev[0]->flags;
 606         concat->mtd.size = subdev[0]->size;
 607         concat->mtd.erasesize = subdev[0]->erasesize;
 608         concat->mtd.writesize = subdev[0]->writesize;
 609         concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 610         concat->mtd.oobsize = subdev[0]->oobsize;
 611         concat->mtd.oobavail = subdev[0]->oobavail;
 612         if (subdev[0]->read_oob)
 613                 concat->mtd.read_oob = concat_read_oob;
 614         if (subdev[0]->write_oob)
 615                 concat->mtd.write_oob = concat_write_oob;
 616         if (subdev[0]->block_isbad)
 617                 concat->mtd.block_isbad = concat_block_isbad;
 618         if (subdev[0]->block_markbad)
 619                 concat->mtd.block_markbad = concat_block_markbad;
 620
 621         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 622
 623         concat->subdev[0] = subdev[0];
 624
 625         for (i = 1; i < num_devs; i++) {
 626                 if (concat->mtd.type != subdev[i]->type) {
 627                         kfree(concat);
 628                         printk("Incompatible device type on \"%s\"\n",
 629                                subdev[i]->name);
 630                         return NULL;
 631                 }
 632                 if (concat->mtd.flags != subdev[i]->flags) {
 633                         /*
 634                          * Expect all flags except MTD_WRITEABLE to be
 635                          * equal on all subdevices.
 636                          */
 637                         if ((concat->mtd.flags ^ subdev[i]->
 638                              flags) & ~MTD_WRITEABLE) {
 639                                 kfree(concat);
 640                                 printk("Incompatible device flags on \"%s\"\n",
 641                                        subdev[i]->name);
 642                                 return NULL;
 643                         } else
 644                                 /* if writeable attribute differs,
 645                                    make super device writeable */
 646                                 concat->mtd.flags |=
 647                                     subdev[i]->flags & MTD_WRITEABLE;
 648                 }
 649
 650                 concat->mtd.size += subdev[i]->size;
 651                 concat->mtd.ecc_stats.badblocks +=
 652                         subdev[i]->ecc_stats.badblocks;
 653                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 654                     concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 655                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 656                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
 657                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
 658                         kfree(concat);
 659                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 660                                subdev[i]->name);
 661                         return NULL;
 662                 }
 663                 concat->subdev[i] = subdev[i];
 664
 665         }
 666
 667         concat->mtd.ecclayout = subdev[0]->ecclayout;
 668
 669         concat->num_subdev = num_devs;
 670         concat->mtd.name = name;
 671
 672         concat->mtd.erase = concat_erase;
 673         concat->mtd.read = concat_read;
 674         concat->mtd.write = concat_write;
 675         concat->mtd.sync = concat_sync;
 676         concat->mtd.lock = concat_lock;
 677         concat->mtd.unlock = concat_unlock;
 678
 679         /*
 680          * Combine the erase block size info of the subdevices:
 681          *
 682          * first, walk the map of the new device and see how
 683          * many changes in erase size we have
 684          */
 685         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 686         num_erase_region = 1;
 687         for (i = 0; i < num_devs; i++) {
 688                 if (subdev[i]->numeraseregions == 0) {
 689                         /* current subdevice has uniform erase size */
 690                         if (subdev[i]->erasesize != curr_erasesize) {
 691                                 /* if it differs from the last subdevice's erase size, count it */
 692                                 ++num_erase_region;
 693                                 curr_erasesize = subdev[i]->erasesize;
 694                                 if (curr_erasesize > max_erasesize)
 695                                         max_erasesize = curr_erasesize;
 696                         }
 697                 } else {
 698                         /* current subdevice has variable erase size */
 699                         int j;
 700                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 701
 702                                 /* walk the list of erase regions, count any changes */
 703                                 if (subdev[i]->eraseregions[j].erasesize !=
 704                                     curr_erasesize) {
 705                                         ++num_erase_region;
 706                                         curr_erasesize =
 707                                             subdev[i]->eraseregions[j].
 708                                             erasesize;
 709                                         if (curr_erasesize > max_erasesize)
 710                                                 max_erasesize = curr_erasesize;
 711                                 }
 712                         }
 713                 }
 714         }
 715
 716         if (num_erase_region == 1) {
 717                 /*
 718                  * All subdevices have the same uniform erase size.
 719                  * This is easy:
 720                  */
 721                 concat->mtd.erasesize = curr_erasesize;
 722                 concat->mtd.numeraseregions = 0;
 723         } else {
 724                 uint64_t tmp64;
 725
 726                 /*
 727                  * erase block size varies across the subdevices: allocate
 728                  * space to store the data describing the variable erase regions
 729                  */
 730                 struct mtd_erase_region_info *erase_region_p;
 731                 uint64_t begin, position;
 732
 733                 concat->mtd.erasesize = max_erasesize;
 734                 concat->mtd.numeraseregions = num_erase_region;
 735                 concat->mtd.eraseregions = erase_region_p =
 736                     kmalloc(num_erase_region *
 737                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 738                 if (!erase_region_p) {
 739                         kfree(concat);
 740                         printk
 741                             ("memory allocation error while creating erase region list"
 742                              " for device \"%s\"\n", name);
 743                         return NULL;
 744                 }
 745
 746                 /*
 747                  * walk the map of the new device once more and fill in
 748                  * in erase region info:
 749                  */
 750                 curr_erasesize = subdev[0]->erasesize;
 751                 begin = position = 0;
 752                 for (i = 0; i < num_devs; i++) {
 753                         if (subdev[i]->numeraseregions == 0) {
 754                                 /* current subdevice has uniform erase size */
 755                                 if (subdev[i]->erasesize != curr_erasesize) {
 756                                         /*
 757                                          *  fill in an mtd_erase_region_info structure for the area
 758                                          *  we have walked so far:
 759                                          */
 760                                         erase_region_p->offset = begin;
 761                                         erase_region_p->erasesize =
 762                                             curr_erasesize;
 763                                         tmp64 = position - begin;
 764                                         do_div(tmp64, curr_erasesize);
 765                                         erase_region_p->numblocks = tmp64;
 766                                         begin = position;
 767
 768                                         curr_erasesize = subdev[i]->erasesize;
 769                                         ++erase_region_p;
 770                                 }
 771                                 position += subdev[i]->size;
 772                         } else {
 773                                 /* current subdevice has variable erase size */
 774                                 int j;
 775                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 776                                         /* walk the list of erase regions, count any changes */
 777                                         if (subdev[i]->eraseregions[j].
 778                                             erasesize != curr_erasesize) {
 779                                                 erase_region_p->offset = begin;
 780                                                 erase_region_p->erasesize =
 781                                                     curr_erasesize;
 782                                                 tmp64 = position - begin;
 783                                                 do_div(tmp64, curr_erasesize);
 784                                                 erase_region_p->numblocks = tmp64;
 785                                                 begin = position;
 786
 787                                                 curr_erasesize =
 788                                                     subdev[i]->eraseregions[j].
 789                                                     erasesize;
 790                                                 ++erase_region_p;
 791                                         }
 792                                         position +=
 793                                             subdev[i]->eraseregions[j].
 794                                             numblocks * (uint64_t)curr_erasesize;
 795                                 }
 796                         }
 797                 }
 798                 /* Now write the final entry */
 799                 erase_region_p->offset = begin;
 800                 erase_region_p->erasesize = curr_erasesize;
 801                 tmp64 = position - begin;
 802                 do_div(tmp64, curr_erasesize);
 803                 erase_region_p->numblocks = tmp64;
 804         }
 805
 806         return &concat->mtd;
 807 }