drivers/mtd/mtdconcat.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * MTD device concatenation layer
   4  *
   5  * Copyright © 2002 Robert Kaiser <rkaiser@sysgo.de>
   6  * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * NAND support by Christian Gan <cgan@iders.ca>
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/sched.h>
  15 #include <linux/types.h>
  16 #include <linux/backing-dev.h>
  17
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/mtd/concat.h>
  20
  21 #include <asm/div64.h>
  22
  23 /*
  24  * Our storage structure:
  25  * Subdev points to an array of pointers to struct mtd_info objects
  26  * which is allocated along with this structure
  27  *
  28  */
  29 struct mtd_concat {
  30         struct mtd_info mtd;
  31         int num_subdev;
  32         struct mtd_info **subdev;
  33 };
  34
  35 /*
  36  * how to calculate the size required for the above structure,
  37  * including the pointer array subdev points to:
  38  */
  39 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  40         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  41
  42 /*
  43  * Given a pointer to the MTD object in the mtd_concat structure,
  44  * we can retrieve the pointer to that structure with this macro.
  45  */
  46 #define CONCAT(x)  ((struct mtd_concat *)(x))
  47
  48 /*
  49  * MTD methods which look up the relevant subdevice, translate the
  50  * effective address and pass through to the subdevice.
  51  */
  52
  53 static int
  54 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  55             size_t * retlen, u_char * buf)
  56 {
  57         struct mtd_concat *concat = CONCAT(mtd);
  58         int ret = 0, err;
  59         int i;
  60
  61         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 = mtd_read(subdev, from, size, &retsize, buf);
  79
  80                 /* Save information about bitflips! */
  81                 if (unlikely(err)) {
  82                         if (mtd_is_eccerr(err)) {
  83                                 mtd->ecc_stats.failed++;
  84                                 ret = err;
  85                         } else if (mtd_is_bitflip(err)) {
  86                                 mtd->ecc_stats.corrected++;
  87                                 /* Do not overwrite -EBADMSG !! */
  88                                 if (!ret)
  89                                         ret = err;
  90                         } else
  91                                 return err;
  92                 }
  93
  94                 *retlen += retsize;
  95                 len -= size;
  96                 if (len == 0)
  97                         return ret;
  98
  99                 buf += size;
 100                 from = 0;
 101         }
 102         return -EINVAL;
 103 }
 104
 105 static int
 106 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 107              size_t * retlen, const u_char * buf)
 108 {
 109         struct mtd_concat *concat = CONCAT(mtd);
 110         int err = -EINVAL;
 111         int i;
 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                 err = mtd_write(subdev, to, size, &retsize, buf);
 128                 if (err)
 129                         break;
 130
 131                 *retlen += retsize;
 132                 len -= size;
 133                 if (len == 0)
 134                         break;
 135
 136                 err = -EINVAL;
 137                 buf += size;
 138                 to = 0;
 139         }
 140         return err;
 141 }
 142
 143 static int
 144 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 145                 unsigned long count, loff_t to, size_t * retlen)
 146 {
 147         struct mtd_concat *concat = CONCAT(mtd);
 148         struct kvec *vecs_copy;
 149         unsigned long entry_low, entry_high;
 150         size_t total_len = 0;
 151         int i;
 152         int err = -EINVAL;
 153
 154         /* Calculate total length of data */
 155         for (i = 0; i < count; i++)
 156                 total_len += vecs[i].iov_len;
 157
 158         /* Check alignment */
 159         if (mtd->writesize > 1) {
 160                 uint64_t __to = to;
 161                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
 162                         return -EINVAL;
 163         }
 164
 165         /* make a copy of vecs */
 166         vecs_copy = kmemdup(vecs, sizeof(struct kvec) * count, GFP_KERNEL);
 167         if (!vecs_copy)
 168                 return -ENOMEM;
 169
 170         entry_low = 0;
 171         for (i = 0; i < concat->num_subdev; i++) {
 172                 struct mtd_info *subdev = concat->subdev[i];
 173                 size_t size, wsize, retsize, old_iov_len;
 174
 175                 if (to >= subdev->size) {
 176                         to -= subdev->size;
 177                         continue;
 178                 }
 179
 180                 size = min_t(uint64_t, total_len, subdev->size - to);
 181                 wsize = size; /* store for future use */
 182
 183                 entry_high = entry_low;
 184                 while (entry_high < count) {
 185                         if (size <= vecs_copy[entry_high].iov_len)
 186                                 break;
 187                         size -= vecs_copy[entry_high++].iov_len;
 188                 }
 189
 190                 old_iov_len = vecs_copy[entry_high].iov_len;
 191                 vecs_copy[entry_high].iov_len = size;
 192
 193                 err = mtd_writev(subdev, &vecs_copy[entry_low],
 194                                  entry_high - entry_low + 1, to, &retsize);
 195
 196                 vecs_copy[entry_high].iov_len = old_iov_len - size;
 197                 vecs_copy[entry_high].iov_base += size;
 198
 199                 entry_low = entry_high;
 200
 201                 if (err)
 202                         break;
 203
 204                 *retlen += retsize;
 205                 total_len -= wsize;
 206
 207                 if (total_len == 0)
 208                         break;
 209
 210                 err = -EINVAL;
 211                 to = 0;
 212         }
 213
 214         kfree(vecs_copy);
 215         return err;
 216 }
 217
 218 static int
 219 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 220 {
 221         struct mtd_concat *concat = CONCAT(mtd);
 222         struct mtd_oob_ops devops = *ops;
 223         int i, err, ret = 0;
 224
 225         ops->retlen = ops->oobretlen = 0;
 226
 227         for (i = 0; i < concat->num_subdev; i++) {
 228                 struct mtd_info *subdev = concat->subdev[i];
 229
 230                 if (from >= subdev->size) {
 231                         from -= subdev->size;
 232                         continue;
 233                 }
 234
 235                 /* partial read ? */
 236                 if (from + devops.len > subdev->size)
 237                         devops.len = subdev->size - from;
 238
 239                 err = mtd_read_oob(subdev, from, &devops);
 240                 ops->retlen += devops.retlen;
 241                 ops->oobretlen += devops.oobretlen;
 242
 243                 /* Save information about bitflips! */
 244                 if (unlikely(err)) {
 245                         if (mtd_is_eccerr(err)) {
 246                                 mtd->ecc_stats.failed++;
 247                                 ret = err;
 248                         } else if (mtd_is_bitflip(err)) {
 249                                 mtd->ecc_stats.corrected++;
 250                                 /* Do not overwrite -EBADMSG !! */
 251                                 if (!ret)
 252                                         ret = err;
 253                         } else
 254                                 return err;
 255                 }
 256
 257                 if (devops.datbuf) {
 258                         devops.len = ops->len - ops->retlen;
 259                         if (!devops.len)
 260                                 return ret;
 261                         devops.datbuf += devops.retlen;
 262                 }
 263                 if (devops.oobbuf) {
 264                         devops.ooblen = ops->ooblen - ops->oobretlen;
 265                         if (!devops.ooblen)
 266                                 return ret;
 267                         devops.oobbuf += ops->oobretlen;
 268                 }
 269
 270                 from = 0;
 271         }
 272         return -EINVAL;
 273 }
 274
 275 static int
 276 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 277 {
 278         struct mtd_concat *concat = CONCAT(mtd);
 279         struct mtd_oob_ops devops = *ops;
 280         int i, err;
 281
 282         if (!(mtd->flags & MTD_WRITEABLE))
 283                 return -EROFS;
 284
 285         ops->retlen = ops->oobretlen = 0;
 286
 287         for (i = 0; i < concat->num_subdev; i++) {
 288                 struct mtd_info *subdev = concat->subdev[i];
 289
 290                 if (to >= subdev->size) {
 291                         to -= subdev->size;
 292                         continue;
 293                 }
 294
 295                 /* partial write ? */
 296                 if (to + devops.len > subdev->size)
 297                         devops.len = subdev->size - to;
 298
 299                 err = mtd_write_oob(subdev, to, &devops);
 300                 ops->retlen += devops.retlen;
 301                 ops->oobretlen += devops.oobretlen;
 302                 if (err)
 303                         return err;
 304
 305                 if (devops.datbuf) {
 306                         devops.len = ops->len - ops->retlen;
 307                         if (!devops.len)
 308                                 return 0;
 309                         devops.datbuf += devops.retlen;
 310                 }
 311                 if (devops.oobbuf) {
 312                         devops.ooblen = ops->ooblen - ops->oobretlen;
 313                         if (!devops.ooblen)
 314                                 return 0;
 315                         devops.oobbuf += devops.oobretlen;
 316                 }
 317                 to = 0;
 318         }
 319         return -EINVAL;
 320 }
 321
 322 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 323 {
 324         struct mtd_concat *concat = CONCAT(mtd);
 325         struct mtd_info *subdev;
 326         int i, err;
 327         uint64_t length, offset = 0;
 328         struct erase_info *erase;
 329
 330         /*
 331          * Check for proper erase block alignment of the to-be-erased area.
 332          * It is easier to do this based on the super device's erase
 333          * region info rather than looking at each particular sub-device
 334          * in turn.
 335          */
 336         if (!concat->mtd.numeraseregions) {
 337                 /* the easy case: device has uniform erase block size */
 338                 if (instr->addr & (concat->mtd.erasesize - 1))
 339                         return -EINVAL;
 340                 if (instr->len & (concat->mtd.erasesize - 1))
 341                         return -EINVAL;
 342         } else {
 343                 /* device has variable erase size */
 344                 struct mtd_erase_region_info *erase_regions =
 345                     concat->mtd.eraseregions;
 346
 347                 /*
 348                  * Find the erase region where the to-be-erased area begins:
 349                  */
 350                 for (i = 0; i < concat->mtd.numeraseregions &&
 351                      instr->addr >= erase_regions[i].offset; i++) ;
 352                 --i;
 353
 354                 /*
 355                  * Now erase_regions[i] is the region in which the
 356                  * to-be-erased area begins. Verify that the starting
 357                  * offset is aligned to this region's erase size:
 358                  */
 359                 if (i < 0 || instr->addr & (erase_regions[i].erasesize - 1))
 360                         return -EINVAL;
 361
 362                 /*
 363                  * now find the erase region where the to-be-erased area ends:
 364                  */
 365                 for (; i < concat->mtd.numeraseregions &&
 366                      (instr->addr + instr->len) >= erase_regions[i].offset;
 367                      ++i) ;
 368                 --i;
 369                 /*
 370                  * check if the ending offset is aligned to this region's erase size
 371                  */
 372                 if (i < 0 || ((instr->addr + instr->len) &
 373                                         (erase_regions[i].erasesize - 1)))
 374                         return -EINVAL;
 375         }
 376
 377         /* make a local copy of instr to avoid modifying the caller's struct */
 378         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 379
 380         if (!erase)
 381                 return -ENOMEM;
 382
 383         *erase = *instr;
 384         length = instr->len;
 385
 386         /*
 387          * find the subdevice where the to-be-erased area begins, adjust
 388          * starting offset to be relative to the subdevice start
 389          */
 390         for (i = 0; i < concat->num_subdev; i++) {
 391                 subdev = concat->subdev[i];
 392                 if (subdev->size <= erase->addr) {
 393                         erase->addr -= subdev->size;
 394                         offset += subdev->size;
 395                 } else {
 396                         break;
 397                 }
 398         }
 399
 400         /* must never happen since size limit has been verified above */
 401         BUG_ON(i >= concat->num_subdev);
 402
 403         /* now do the erase: */
 404         err = 0;
 405         for (; length > 0; i++) {
 406                 /* loop for all subdevices affected by this request */
 407                 subdev = concat->subdev[i];     /* get current subdevice */
 408
 409                 /* limit length to subdevice's size: */
 410                 if (erase->addr + length > subdev->size)
 411                         erase->len = subdev->size - erase->addr;
 412                 else
 413                         erase->len = length;
 414
 415                 length -= erase->len;
 416                 if ((err = mtd_erase(subdev, erase))) {
 417                         /* sanity check: should never happen since
 418                          * block alignment has been checked above */
 419                         BUG_ON(err == -EINVAL);
 420                         if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
 421                                 instr->fail_addr = erase->fail_addr + offset;
 422                         break;
 423                 }
 424                 /*
 425                  * erase->addr specifies the offset of the area to be
 426                  * erased *within the current subdevice*. It can be
 427                  * non-zero only the first time through this loop, i.e.
 428                  * for the first subdevice where blocks need to be erased.
 429                  * All the following erases must begin at the start of the
 430                  * current subdevice, i.e. at offset zero.
 431                  */
 432                 erase->addr = 0;
 433                 offset += subdev->size;
 434         }
 435         kfree(erase);
 436
 437         return err;
 438 }
 439
 440 static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 441 {
 442         struct mtd_concat *concat = CONCAT(mtd);
 443         int i, err = -EINVAL;
 444
 445         for (i = 0; i < concat->num_subdev; i++) {
 446                 struct mtd_info *subdev = concat->subdev[i];
 447                 uint64_t size;
 448
 449                 if (ofs >= subdev->size) {
 450                         size = 0;
 451                         ofs -= subdev->size;
 452                         continue;
 453                 }
 454                 if (ofs + len > subdev->size)
 455                         size = subdev->size - ofs;
 456                 else
 457                         size = len;
 458
 459                 err = mtd_lock(subdev, ofs, size);
 460                 if (err)
 461                         break;
 462
 463                 len -= size;
 464                 if (len == 0)
 465                         break;
 466
 467                 err = -EINVAL;
 468                 ofs = 0;
 469         }
 470
 471         return err;
 472 }
 473
 474 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 475 {
 476         struct mtd_concat *concat = CONCAT(mtd);
 477         int i, err = 0;
 478
 479         for (i = 0; i < concat->num_subdev; i++) {
 480                 struct mtd_info *subdev = concat->subdev[i];
 481                 uint64_t size;
 482
 483                 if (ofs >= subdev->size) {
 484                         size = 0;
 485                         ofs -= subdev->size;
 486                         continue;
 487                 }
 488                 if (ofs + len > subdev->size)
 489                         size = subdev->size - ofs;
 490                 else
 491                         size = len;
 492
 493                 err = mtd_unlock(subdev, ofs, size);
 494                 if (err)
 495                         break;
 496
 497                 len -= size;
 498                 if (len == 0)
 499                         break;
 500
 501                 err = -EINVAL;
 502                 ofs = 0;
 503         }
 504
 505         return err;
 506 }
 507
 508 static void concat_sync(struct mtd_info *mtd)
 509 {
 510         struct mtd_concat *concat = CONCAT(mtd);
 511         int i;
 512
 513         for (i = 0; i < concat->num_subdev; i++) {
 514                 struct mtd_info *subdev = concat->subdev[i];
 515                 mtd_sync(subdev);
 516         }
 517 }
 518
 519 static int concat_suspend(struct mtd_info *mtd)
 520 {
 521         struct mtd_concat *concat = CONCAT(mtd);
 522         int i, rc = 0;
 523
 524         for (i = 0; i < concat->num_subdev; i++) {
 525                 struct mtd_info *subdev = concat->subdev[i];
 526                 if ((rc = mtd_suspend(subdev)) < 0)
 527                         return rc;
 528         }
 529         return rc;
 530 }
 531
 532 static void concat_resume(struct mtd_info *mtd)
 533 {
 534         struct mtd_concat *concat = CONCAT(mtd);
 535         int i;
 536
 537         for (i = 0; i < concat->num_subdev; i++) {
 538                 struct mtd_info *subdev = concat->subdev[i];
 539                 mtd_resume(subdev);
 540         }
 541 }
 542
 543 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 544 {
 545         struct mtd_concat *concat = CONCAT(mtd);
 546         int i, res = 0;
 547
 548         if (!mtd_can_have_bb(concat->subdev[0]))
 549                 return res;
 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                 res = mtd_block_isbad(subdev, ofs);
 560                 break;
 561         }
 562
 563         return res;
 564 }
 565
 566 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 567 {
 568         struct mtd_concat *concat = CONCAT(mtd);
 569         int i, err = -EINVAL;
 570
 571         for (i = 0; i < concat->num_subdev; i++) {
 572                 struct mtd_info *subdev = concat->subdev[i];
 573
 574                 if (ofs >= subdev->size) {
 575                         ofs -= subdev->size;
 576                         continue;
 577                 }
 578
 579                 err = mtd_block_markbad(subdev, ofs);
 580                 if (!err)
 581                         mtd->ecc_stats.badblocks++;
 582                 break;
 583         }
 584
 585         return err;
 586 }
 587
 588 /*
 589  * This function constructs a virtual MTD device by concatenating
 590  * num_devs MTD devices. A pointer to the new device object is
 591  * stored to *new_dev upon success. This function does _not_
 592  * register any devices: this is the caller's responsibility.
 593  */
 594 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 595                                    int num_devs,        /* number of subdevices      */
 596                                    const char *name)
 597 {                               /* name for the new device   */
 598         int i;
 599         size_t size;
 600         struct mtd_concat *concat;
 601         uint32_t max_erasesize, curr_erasesize;
 602         int num_erase_region;
 603         int max_writebufsize = 0;
 604
 605         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 606         for (i = 0; i < num_devs; i++)
 607                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 608         printk(KERN_NOTICE "into device \"%s\"\n", name);
 609
 610         /* allocate the device structure */
 611         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 612         concat = kzalloc(size, GFP_KERNEL);
 613         if (!concat) {
 614                 printk
 615                     ("memory allocation error while creating concatenated device \"%s\"\n",
 616                      name);
 617                 return NULL;
 618         }
 619         concat->subdev = (struct mtd_info **) (concat + 1);
 620
 621         /*
 622          * Set up the new "super" device's MTD object structure, check for
 623          * incompatibilities between the subdevices.
 624          */
 625         concat->mtd.type = subdev[0]->type;
 626         concat->mtd.flags = subdev[0]->flags;
 627         concat->mtd.size = subdev[0]->size;
 628         concat->mtd.erasesize = subdev[0]->erasesize;
 629         concat->mtd.writesize = subdev[0]->writesize;
 630
 631         for (i = 0; i < num_devs; i++)
 632                 if (max_writebufsize < subdev[i]->writebufsize)
 633                         max_writebufsize = subdev[i]->writebufsize;
 634         concat->mtd.writebufsize = max_writebufsize;
 635
 636         concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 637         concat->mtd.oobsize = subdev[0]->oobsize;
 638         concat->mtd.oobavail = subdev[0]->oobavail;
 639         if (subdev[0]->_writev)
 640                 concat->mtd._writev = concat_writev;
 641         if (subdev[0]->_read_oob)
 642                 concat->mtd._read_oob = concat_read_oob;
 643         if (subdev[0]->_write_oob)
 644                 concat->mtd._write_oob = concat_write_oob;
 645         if (subdev[0]->_block_isbad)
 646                 concat->mtd._block_isbad = concat_block_isbad;
 647         if (subdev[0]->_block_markbad)
 648                 concat->mtd._block_markbad = concat_block_markbad;
 649
 650         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 651
 652         concat->subdev[0] = subdev[0];
 653
 654         for (i = 1; i < num_devs; i++) {
 655                 if (concat->mtd.type != subdev[i]->type) {
 656                         kfree(concat);
 657                         printk("Incompatible device type on \"%s\"\n",
 658                                subdev[i]->name);
 659                         return NULL;
 660                 }
 661                 if (concat->mtd.flags != subdev[i]->flags) {
 662                         /*
 663                          * Expect all flags except MTD_WRITEABLE to be
 664                          * equal on all subdevices.
 665                          */
 666                         if ((concat->mtd.flags ^ subdev[i]->
 667                              flags) & ~MTD_WRITEABLE) {
 668                                 kfree(concat);
 669                                 printk("Incompatible device flags on \"%s\"\n",
 670                                        subdev[i]->name);
 671                                 return NULL;
 672                         } else
 673                                 /* if writeable attribute differs,
 674                                    make super device writeable */
 675                                 concat->mtd.flags |=
 676                                     subdev[i]->flags & MTD_WRITEABLE;
 677                 }
 678
 679                 concat->mtd.size += subdev[i]->size;
 680                 concat->mtd.ecc_stats.badblocks +=
 681                         subdev[i]->ecc_stats.badblocks;
 682                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 683                     concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 684                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 685                     !concat->mtd._read_oob  != !subdev[i]->_read_oob ||
 686                     !concat->mtd._write_oob != !subdev[i]->_write_oob) {
 687                         kfree(concat);
 688                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 689                                subdev[i]->name);
 690                         return NULL;
 691                 }
 692                 concat->subdev[i] = subdev[i];
 693
 694         }
 695
 696         mtd_set_ooblayout(&concat->mtd, subdev[0]->ooblayout);
 697
 698         concat->num_subdev = num_devs;
 699         concat->mtd.name = name;
 700
 701         concat->mtd._erase = concat_erase;
 702         concat->mtd._read = concat_read;
 703         concat->mtd._write = concat_write;
 704         concat->mtd._sync = concat_sync;
 705         concat->mtd._lock = concat_lock;
 706         concat->mtd._unlock = concat_unlock;
 707         concat->mtd._suspend = concat_suspend;
 708         concat->mtd._resume = concat_resume;
 709
 710         /*
 711          * Combine the erase block size info of the subdevices:
 712          *
 713          * first, walk the map of the new device and see how
 714          * many changes in erase size we have
 715          */
 716         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 717         num_erase_region = 1;
 718         for (i = 0; i < num_devs; i++) {
 719                 if (subdev[i]->numeraseregions == 0) {
 720                         /* current subdevice has uniform erase size */
 721                         if (subdev[i]->erasesize != curr_erasesize) {
 722                                 /* if it differs from the last subdevice's erase size, count it */
 723                                 ++num_erase_region;
 724                                 curr_erasesize = subdev[i]->erasesize;
 725                                 if (curr_erasesize > max_erasesize)
 726                                         max_erasesize = curr_erasesize;
 727                         }
 728                 } else {
 729                         /* current subdevice has variable erase size */
 730                         int j;
 731                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 732
 733                                 /* walk the list of erase regions, count any changes */
 734                                 if (subdev[i]->eraseregions[j].erasesize !=
 735                                     curr_erasesize) {
 736                                         ++num_erase_region;
 737                                         curr_erasesize =
 738                                             subdev[i]->eraseregions[j].
 739                                             erasesize;
 740                                         if (curr_erasesize > max_erasesize)
 741                                                 max_erasesize = curr_erasesize;
 742                                 }
 743                         }
 744                 }
 745         }
 746
 747         if (num_erase_region == 1) {
 748                 /*
 749                  * All subdevices have the same uniform erase size.
 750                  * This is easy:
 751                  */
 752                 concat->mtd.erasesize = curr_erasesize;
 753                 concat->mtd.numeraseregions = 0;
 754         } else {
 755                 uint64_t tmp64;
 756
 757                 /*
 758                  * erase block size varies across the subdevices: allocate
 759                  * space to store the data describing the variable erase regions
 760                  */
 761                 struct mtd_erase_region_info *erase_region_p;
 762                 uint64_t begin, position;
 763
 764                 concat->mtd.erasesize = max_erasesize;
 765                 concat->mtd.numeraseregions = num_erase_region;
 766                 concat->mtd.eraseregions = erase_region_p =
 767                     kmalloc_array(num_erase_region,
 768                                   sizeof(struct mtd_erase_region_info),
 769                                   GFP_KERNEL);
 770                 if (!erase_region_p) {
 771                         kfree(concat);
 772                         printk
 773                             ("memory allocation error while creating erase region list"
 774                              " for device \"%s\"\n", name);
 775                         return NULL;
 776                 }
 777
 778                 /*
 779                  * walk the map of the new device once more and fill in
 780                  * in erase region info:
 781                  */
 782                 curr_erasesize = subdev[0]->erasesize;
 783                 begin = position = 0;
 784                 for (i = 0; i < num_devs; i++) {
 785                         if (subdev[i]->numeraseregions == 0) {
 786                                 /* current subdevice has uniform erase size */
 787                                 if (subdev[i]->erasesize != curr_erasesize) {
 788                                         /*
 789                                          *  fill in an mtd_erase_region_info structure for the area
 790                                          *  we have walked so far:
 791                                          */
 792                                         erase_region_p->offset = begin;
 793                                         erase_region_p->erasesize =
 794                                             curr_erasesize;
 795                                         tmp64 = position - begin;
 796                                         do_div(tmp64, curr_erasesize);
 797                                         erase_region_p->numblocks = tmp64;
 798                                         begin = position;
 799
 800                                         curr_erasesize = subdev[i]->erasesize;
 801                                         ++erase_region_p;
 802                                 }
 803                                 position += subdev[i]->size;
 804                         } else {
 805                                 /* current subdevice has variable erase size */
 806                                 int j;
 807                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 808                                         /* walk the list of erase regions, count any changes */
 809                                         if (subdev[i]->eraseregions[j].
 810                                             erasesize != curr_erasesize) {
 811                                                 erase_region_p->offset = begin;
 812                                                 erase_region_p->erasesize =
 813                                                     curr_erasesize;
 814                                                 tmp64 = position - begin;
 815                                                 do_div(tmp64, curr_erasesize);
 816                                                 erase_region_p->numblocks = tmp64;
 817                                                 begin = position;
 818
 819                                                 curr_erasesize =
 820                                                     subdev[i]->eraseregions[j].
 821                                                     erasesize;
 822                                                 ++erase_region_p;
 823                                         }
 824                                         position +=
 825                                             subdev[i]->eraseregions[j].
 826                                             numblocks * (uint64_t)curr_erasesize;
 827                                 }
 828                         }
 829                 }
 830                 /* Now write the final entry */
 831                 erase_region_p->offset = begin;
 832                 erase_region_p->erasesize = curr_erasesize;
 833                 tmp64 = position - begin;
 834                 do_div(tmp64, curr_erasesize);
 835                 erase_region_p->numblocks = tmp64;
 836         }
 837
 838         return &concat->mtd;
 839 }
 840
 841 /*
 842  * This function destroys an MTD object obtained from concat_mtd_devs()
 843  */
 844
 845 void mtd_concat_destroy(struct mtd_info *mtd)
 846 {
 847         struct mtd_concat *concat = CONCAT(mtd);
 848         if (concat->mtd.numeraseregions)
 849                 kfree(concat->mtd.eraseregions);
 850         kfree(concat);
 851 }
 852
 853 EXPORT_SYMBOL(mtd_concat_create);
 854 EXPORT_SYMBOL(mtd_concat_destroy);
 855
 856 MODULE_LICENSE("GPL");
 857 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 858 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");