drivers/mtd/mtdconcat.c

   1 /*
   2  * MTD device concatenation layer
   3  *
   4  * Copyright © 2002 Robert Kaiser <rkaiser@sysgo.de>
   5  * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
   6  *
   7  * NAND support by Christian Gan <cgan@iders.ca>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  22  *
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/slab.h>
  28 #include <linux/sched.h>
  29 #include <linux/types.h>
  30 #include <linux/backing-dev.h>
  31
  32 #include <linux/mtd/mtd.h>
  33 #include <linux/mtd/concat.h>
  34
  35 #include <asm/div64.h>
  36
  37 /*
  38  * Our storage structure:
  39  * Subdev points to an array of pointers to struct mtd_info objects
  40  * which is allocated along with this structure
  41  *
  42  */
  43 struct mtd_concat {
  44         struct mtd_info mtd;
  45         int num_subdev;
  46         struct mtd_info **subdev;
  47 };
  48
  49 /*
  50  * how to calculate the size required for the above structure,
  51  * including the pointer array subdev points to:
  52  */
  53 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
  54         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
  55
  56 /*
  57  * Given a pointer to the MTD object in the mtd_concat structure,
  58  * we can retrieve the pointer to that structure with this macro.
  59  */
  60 #define CONCAT(x)  ((struct mtd_concat *)(x))
  61
  62 /*
  63  * MTD methods which look up the relevant subdevice, translate the
  64  * effective address and pass through to the subdevice.
  65  */
  66
  67 static int
  68 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
  69             size_t * retlen, u_char * buf)
  70 {
  71         struct mtd_concat *concat = CONCAT(mtd);
  72         int ret = 0, err;
  73         int i;
  74
  75         for (i = 0; i < concat->num_subdev; i++) {
  76                 struct mtd_info *subdev = concat->subdev[i];
  77                 size_t size, retsize;
  78
  79                 if (from >= subdev->size) {
  80                         /* Not destined for this subdev */
  81                         size = 0;
  82                         from -= subdev->size;
  83                         continue;
  84                 }
  85                 if (from + len > subdev->size)
  86                         /* First part goes into this subdev */
  87                         size = subdev->size - from;
  88                 else
  89                         /* Entire transaction goes into this subdev */
  90                         size = len;
  91
  92                 err = mtd_read(subdev, from, size, &retsize, buf);
  93
  94                 /* Save information about bitflips! */
  95                 if (unlikely(err)) {
  96                         if (mtd_is_eccerr(err)) {
  97                                 mtd->ecc_stats.failed++;
  98                                 ret = err;
  99                         } else if (mtd_is_bitflip(err)) {
 100                                 mtd->ecc_stats.corrected++;
 101                                 /* Do not overwrite -EBADMSG !! */
 102                                 if (!ret)
 103                                         ret = err;
 104                         } else
 105                                 return err;
 106                 }
 107
 108                 *retlen += retsize;
 109                 len -= size;
 110                 if (len == 0)
 111                         return ret;
 112
 113                 buf += size;
 114                 from = 0;
 115         }
 116         return -EINVAL;
 117 }
 118
 119 static int
 120 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 121              size_t * retlen, const u_char * buf)
 122 {
 123         struct mtd_concat *concat = CONCAT(mtd);
 124         int err = -EINVAL;
 125         int i;
 126
 127         for (i = 0; i < concat->num_subdev; i++) {
 128                 struct mtd_info *subdev = concat->subdev[i];
 129                 size_t size, retsize;
 130
 131                 if (to >= subdev->size) {
 132                         size = 0;
 133                         to -= subdev->size;
 134                         continue;
 135                 }
 136                 if (to + len > subdev->size)
 137                         size = subdev->size - to;
 138                 else
 139                         size = len;
 140
 141                 err = mtd_write(subdev, to, size, &retsize, buf);
 142                 if (err)
 143                         break;
 144
 145                 *retlen += retsize;
 146                 len -= size;
 147                 if (len == 0)
 148                         break;
 149
 150                 err = -EINVAL;
 151                 buf += size;
 152                 to = 0;
 153         }
 154         return err;
 155 }
 156
 157 static int
 158 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 159                 unsigned long count, loff_t to, size_t * retlen)
 160 {
 161         struct mtd_concat *concat = CONCAT(mtd);
 162         struct kvec *vecs_copy;
 163         unsigned long entry_low, entry_high;
 164         size_t total_len = 0;
 165         int i;
 166         int err = -EINVAL;
 167
 168         /* Calculate total length of data */
 169         for (i = 0; i < count; i++)
 170                 total_len += vecs[i].iov_len;
 171
 172         /* Check alignment */
 173         if (mtd->writesize > 1) {
 174                 uint64_t __to = to;
 175                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
 176                         return -EINVAL;
 177         }
 178
 179         /* make a copy of vecs */
 180         vecs_copy = kmemdup(vecs, sizeof(struct kvec) * count, GFP_KERNEL);
 181         if (!vecs_copy)
 182                 return -ENOMEM;
 183
 184         entry_low = 0;
 185         for (i = 0; i < concat->num_subdev; i++) {
 186                 struct mtd_info *subdev = concat->subdev[i];
 187                 size_t size, wsize, retsize, old_iov_len;
 188
 189                 if (to >= subdev->size) {
 190                         to -= subdev->size;
 191                         continue;
 192                 }
 193
 194                 size = min_t(uint64_t, total_len, subdev->size - to);
 195                 wsize = size; /* store for future use */
 196
 197                 entry_high = entry_low;
 198                 while (entry_high < count) {
 199                         if (size <= vecs_copy[entry_high].iov_len)
 200                                 break;
 201                         size -= vecs_copy[entry_high++].iov_len;
 202                 }
 203
 204                 old_iov_len = vecs_copy[entry_high].iov_len;
 205                 vecs_copy[entry_high].iov_len = size;
 206
 207                 err = mtd_writev(subdev, &vecs_copy[entry_low],
 208                                  entry_high - entry_low + 1, to, &retsize);
 209
 210                 vecs_copy[entry_high].iov_len = old_iov_len - size;
 211                 vecs_copy[entry_high].iov_base += size;
 212
 213                 entry_low = entry_high;
 214
 215                 if (err)
 216                         break;
 217
 218                 *retlen += retsize;
 219                 total_len -= wsize;
 220
 221                 if (total_len == 0)
 222                         break;
 223
 224                 err = -EINVAL;
 225                 to = 0;
 226         }
 227
 228         kfree(vecs_copy);
 229         return err;
 230 }
 231
 232 static int
 233 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 234 {
 235         struct mtd_concat *concat = CONCAT(mtd);
 236         struct mtd_oob_ops devops = *ops;
 237         int i, err, ret = 0;
 238
 239         ops->retlen = ops->oobretlen = 0;
 240
 241         for (i = 0; i < concat->num_subdev; i++) {
 242                 struct mtd_info *subdev = concat->subdev[i];
 243
 244                 if (from >= subdev->size) {
 245                         from -= subdev->size;
 246                         continue;
 247                 }
 248
 249                 /* partial read ? */
 250                 if (from + devops.len > subdev->size)
 251                         devops.len = subdev->size - from;
 252
 253                 err = mtd_read_oob(subdev, from, &devops);
 254                 ops->retlen += devops.retlen;
 255                 ops->oobretlen += devops.oobretlen;
 256
 257                 /* Save information about bitflips! */
 258                 if (unlikely(err)) {
 259                         if (mtd_is_eccerr(err)) {
 260                                 mtd->ecc_stats.failed++;
 261                                 ret = err;
 262                         } else if (mtd_is_bitflip(err)) {
 263                                 mtd->ecc_stats.corrected++;
 264                                 /* Do not overwrite -EBADMSG !! */
 265                                 if (!ret)
 266                                         ret = err;
 267                         } else
 268                                 return err;
 269                 }
 270
 271                 if (devops.datbuf) {
 272                         devops.len = ops->len - ops->retlen;
 273                         if (!devops.len)
 274                                 return ret;
 275                         devops.datbuf += devops.retlen;
 276                 }
 277                 if (devops.oobbuf) {
 278                         devops.ooblen = ops->ooblen - ops->oobretlen;
 279                         if (!devops.ooblen)
 280                                 return ret;
 281                         devops.oobbuf += ops->oobretlen;
 282                 }
 283
 284                 from = 0;
 285         }
 286         return -EINVAL;
 287 }
 288
 289 static int
 290 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
 291 {
 292         struct mtd_concat *concat = CONCAT(mtd);
 293         struct mtd_oob_ops devops = *ops;
 294         int i, err;
 295
 296         if (!(mtd->flags & MTD_WRITEABLE))
 297                 return -EROFS;
 298
 299         ops->retlen = ops->oobretlen = 0;
 300
 301         for (i = 0; i < concat->num_subdev; i++) {
 302                 struct mtd_info *subdev = concat->subdev[i];
 303
 304                 if (to >= subdev->size) {
 305                         to -= subdev->size;
 306                         continue;
 307                 }
 308
 309                 /* partial write ? */
 310                 if (to + devops.len > subdev->size)
 311                         devops.len = subdev->size - to;
 312
 313                 err = mtd_write_oob(subdev, to, &devops);
 314                 ops->retlen += devops.retlen;
 315                 ops->oobretlen += devops.oobretlen;
 316                 if (err)
 317                         return err;
 318
 319                 if (devops.datbuf) {
 320                         devops.len = ops->len - ops->retlen;
 321                         if (!devops.len)
 322                                 return 0;
 323                         devops.datbuf += devops.retlen;
 324                 }
 325                 if (devops.oobbuf) {
 326                         devops.ooblen = ops->ooblen - ops->oobretlen;
 327                         if (!devops.ooblen)
 328                                 return 0;
 329                         devops.oobbuf += devops.oobretlen;
 330                 }
 331                 to = 0;
 332         }
 333         return -EINVAL;
 334 }
 335
 336 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 337 {
 338         struct mtd_concat *concat = CONCAT(mtd);
 339         struct mtd_info *subdev;
 340         int i, err;
 341         uint64_t length, offset = 0;
 342         struct erase_info *erase;
 343
 344         /*
 345          * Check for proper erase block alignment of the to-be-erased area.
 346          * It is easier to do this based on the super device's erase
 347          * region info rather than looking at each particular sub-device
 348          * in turn.
 349          */
 350         if (!concat->mtd.numeraseregions) {
 351                 /* the easy case: device has uniform erase block size */
 352                 if (instr->addr & (concat->mtd.erasesize - 1))
 353                         return -EINVAL;
 354                 if (instr->len & (concat->mtd.erasesize - 1))
 355                         return -EINVAL;
 356         } else {
 357                 /* device has variable erase size */
 358                 struct mtd_erase_region_info *erase_regions =
 359                     concat->mtd.eraseregions;
 360
 361                 /*
 362                  * Find the erase region where the to-be-erased area begins:
 363                  */
 364                 for (i = 0; i < concat->mtd.numeraseregions &&
 365                      instr->addr >= erase_regions[i].offset; i++) ;
 366                 --i;
 367
 368                 /*
 369                  * Now erase_regions[i] is the region in which the
 370                  * to-be-erased area begins. Verify that the starting
 371                  * offset is aligned to this region's erase size:
 372                  */
 373                 if (i < 0 || instr->addr & (erase_regions[i].erasesize - 1))
 374                         return -EINVAL;
 375
 376                 /*
 377                  * now find the erase region where the to-be-erased area ends:
 378                  */
 379                 for (; i < concat->mtd.numeraseregions &&
 380                      (instr->addr + instr->len) >= erase_regions[i].offset;
 381                      ++i) ;
 382                 --i;
 383                 /*
 384                  * check if the ending offset is aligned to this region's erase size
 385                  */
 386                 if (i < 0 || ((instr->addr + instr->len) &
 387                                         (erase_regions[i].erasesize - 1)))
 388                         return -EINVAL;
 389         }
 390
 391         /* make a local copy of instr to avoid modifying the caller's struct */
 392         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 393
 394         if (!erase)
 395                 return -ENOMEM;
 396
 397         *erase = *instr;
 398         length = instr->len;
 399
 400         /*
 401          * find the subdevice where the to-be-erased area begins, adjust
 402          * starting offset to be relative to the subdevice start
 403          */
 404         for (i = 0; i < concat->num_subdev; i++) {
 405                 subdev = concat->subdev[i];
 406                 if (subdev->size <= erase->addr) {
 407                         erase->addr -= subdev->size;
 408                         offset += subdev->size;
 409                 } else {
 410                         break;
 411                 }
 412         }
 413
 414         /* must never happen since size limit has been verified above */
 415         BUG_ON(i >= concat->num_subdev);
 416
 417         /* now do the erase: */
 418         err = 0;
 419         for (; length > 0; i++) {
 420                 /* loop for all subdevices affected by this request */
 421                 subdev = concat->subdev[i];     /* get current subdevice */
 422
 423                 /* limit length to subdevice's size: */
 424                 if (erase->addr + length > subdev->size)
 425                         erase->len = subdev->size - erase->addr;
 426                 else
 427                         erase->len = length;
 428
 429                 length -= erase->len;
 430                 if ((err = mtd_erase(subdev, erase))) {
 431                         /* sanity check: should never happen since
 432                          * block alignment has been checked above */
 433                         BUG_ON(err == -EINVAL);
 434                         if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
 435                                 instr->fail_addr = erase->fail_addr + offset;
 436                         break;
 437                 }
 438                 /*
 439                  * erase->addr specifies the offset of the area to be
 440                  * erased *within the current subdevice*. It can be
 441                  * non-zero only the first time through this loop, i.e.
 442                  * for the first subdevice where blocks need to be erased.
 443                  * All the following erases must begin at the start of the
 444                  * current subdevice, i.e. at offset zero.
 445                  */
 446                 erase->addr = 0;
 447                 offset += subdev->size;
 448         }
 449         kfree(erase);
 450
 451         return err;
 452 }
 453
 454 static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 455 {
 456         struct mtd_concat *concat = CONCAT(mtd);
 457         int i, err = -EINVAL;
 458
 459         for (i = 0; i < concat->num_subdev; i++) {
 460                 struct mtd_info *subdev = concat->subdev[i];
 461                 uint64_t size;
 462
 463                 if (ofs >= subdev->size) {
 464                         size = 0;
 465                         ofs -= subdev->size;
 466                         continue;
 467                 }
 468                 if (ofs + len > subdev->size)
 469                         size = subdev->size - ofs;
 470                 else
 471                         size = len;
 472
 473                 err = mtd_lock(subdev, ofs, size);
 474                 if (err)
 475                         break;
 476
 477                 len -= size;
 478                 if (len == 0)
 479                         break;
 480
 481                 err = -EINVAL;
 482                 ofs = 0;
 483         }
 484
 485         return err;
 486 }
 487
 488 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 489 {
 490         struct mtd_concat *concat = CONCAT(mtd);
 491         int i, err = 0;
 492
 493         for (i = 0; i < concat->num_subdev; i++) {
 494                 struct mtd_info *subdev = concat->subdev[i];
 495                 uint64_t size;
 496
 497                 if (ofs >= subdev->size) {
 498                         size = 0;
 499                         ofs -= subdev->size;
 500                         continue;
 501                 }
 502                 if (ofs + len > subdev->size)
 503                         size = subdev->size - ofs;
 504                 else
 505                         size = len;
 506
 507                 err = mtd_unlock(subdev, ofs, size);
 508                 if (err)
 509                         break;
 510
 511                 len -= size;
 512                 if (len == 0)
 513                         break;
 514
 515                 err = -EINVAL;
 516                 ofs = 0;
 517         }
 518
 519         return err;
 520 }
 521
 522 static void concat_sync(struct mtd_info *mtd)
 523 {
 524         struct mtd_concat *concat = CONCAT(mtd);
 525         int i;
 526
 527         for (i = 0; i < concat->num_subdev; i++) {
 528                 struct mtd_info *subdev = concat->subdev[i];
 529                 mtd_sync(subdev);
 530         }
 531 }
 532
 533 static int concat_suspend(struct mtd_info *mtd)
 534 {
 535         struct mtd_concat *concat = CONCAT(mtd);
 536         int i, rc = 0;
 537
 538         for (i = 0; i < concat->num_subdev; i++) {
 539                 struct mtd_info *subdev = concat->subdev[i];
 540                 if ((rc = mtd_suspend(subdev)) < 0)
 541                         return rc;
 542         }
 543         return rc;
 544 }
 545
 546 static void concat_resume(struct mtd_info *mtd)
 547 {
 548         struct mtd_concat *concat = CONCAT(mtd);
 549         int i;
 550
 551         for (i = 0; i < concat->num_subdev; i++) {
 552                 struct mtd_info *subdev = concat->subdev[i];
 553                 mtd_resume(subdev);
 554         }
 555 }
 556
 557 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 558 {
 559         struct mtd_concat *concat = CONCAT(mtd);
 560         int i, res = 0;
 561
 562         if (!mtd_can_have_bb(concat->subdev[0]))
 563                 return res;
 564
 565         for (i = 0; i < concat->num_subdev; i++) {
 566                 struct mtd_info *subdev = concat->subdev[i];
 567
 568                 if (ofs >= subdev->size) {
 569                         ofs -= subdev->size;
 570                         continue;
 571                 }
 572
 573                 res = mtd_block_isbad(subdev, ofs);
 574                 break;
 575         }
 576
 577         return res;
 578 }
 579
 580 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 581 {
 582         struct mtd_concat *concat = CONCAT(mtd);
 583         int i, err = -EINVAL;
 584
 585         for (i = 0; i < concat->num_subdev; i++) {
 586                 struct mtd_info *subdev = concat->subdev[i];
 587
 588                 if (ofs >= subdev->size) {
 589                         ofs -= subdev->size;
 590                         continue;
 591                 }
 592
 593                 err = mtd_block_markbad(subdev, ofs);
 594                 if (!err)
 595                         mtd->ecc_stats.badblocks++;
 596                 break;
 597         }
 598
 599         return err;
 600 }
 601
 602 /*
 603  * This function constructs a virtual MTD device by concatenating
 604  * num_devs MTD devices. A pointer to the new device object is
 605  * stored to *new_dev upon success. This function does _not_
 606  * register any devices: this is the caller's responsibility.
 607  */
 608 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 609                                    int num_devs,        /* number of subdevices      */
 610                                    const char *name)
 611 {                               /* name for the new device   */
 612         int i;
 613         size_t size;
 614         struct mtd_concat *concat;
 615         uint32_t max_erasesize, curr_erasesize;
 616         int num_erase_region;
 617         int max_writebufsize = 0;
 618
 619         printk(KERN_NOTICE "Concatenating MTD devices:\n");
 620         for (i = 0; i < num_devs; i++)
 621                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 622         printk(KERN_NOTICE "into device \"%s\"\n", name);
 623
 624         /* allocate the device structure */
 625         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 626         concat = kzalloc(size, GFP_KERNEL);
 627         if (!concat) {
 628                 printk
 629                     ("memory allocation error while creating concatenated device \"%s\"\n",
 630                      name);
 631                 return NULL;
 632         }
 633         concat->subdev = (struct mtd_info **) (concat + 1);
 634
 635         /*
 636          * Set up the new "super" device's MTD object structure, check for
 637          * incompatibilities between the subdevices.
 638          */
 639         concat->mtd.type = subdev[0]->type;
 640         concat->mtd.flags = subdev[0]->flags;
 641         concat->mtd.size = subdev[0]->size;
 642         concat->mtd.erasesize = subdev[0]->erasesize;
 643         concat->mtd.writesize = subdev[0]->writesize;
 644
 645         for (i = 0; i < num_devs; i++)
 646                 if (max_writebufsize < subdev[i]->writebufsize)
 647                         max_writebufsize = subdev[i]->writebufsize;
 648         concat->mtd.writebufsize = max_writebufsize;
 649
 650         concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 651         concat->mtd.oobsize = subdev[0]->oobsize;
 652         concat->mtd.oobavail = subdev[0]->oobavail;
 653         if (subdev[0]->_writev)
 654                 concat->mtd._writev = concat_writev;
 655         if (subdev[0]->_read_oob)
 656                 concat->mtd._read_oob = concat_read_oob;
 657         if (subdev[0]->_write_oob)
 658                 concat->mtd._write_oob = concat_write_oob;
 659         if (subdev[0]->_block_isbad)
 660                 concat->mtd._block_isbad = concat_block_isbad;
 661         if (subdev[0]->_block_markbad)
 662                 concat->mtd._block_markbad = concat_block_markbad;
 663
 664         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 665
 666         concat->subdev[0] = subdev[0];
 667
 668         for (i = 1; i < num_devs; i++) {
 669                 if (concat->mtd.type != subdev[i]->type) {
 670                         kfree(concat);
 671                         printk("Incompatible device type on \"%s\"\n",
 672                                subdev[i]->name);
 673                         return NULL;
 674                 }
 675                 if (concat->mtd.flags != subdev[i]->flags) {
 676                         /*
 677                          * Expect all flags except MTD_WRITEABLE to be
 678                          * equal on all subdevices.
 679                          */
 680                         if ((concat->mtd.flags ^ subdev[i]->
 681                              flags) & ~MTD_WRITEABLE) {
 682                                 kfree(concat);
 683                                 printk("Incompatible device flags on \"%s\"\n",
 684                                        subdev[i]->name);
 685                                 return NULL;
 686                         } else
 687                                 /* if writeable attribute differs,
 688                                    make super device writeable */
 689                                 concat->mtd.flags |=
 690                                     subdev[i]->flags & MTD_WRITEABLE;
 691                 }
 692
 693                 concat->mtd.size += subdev[i]->size;
 694                 concat->mtd.ecc_stats.badblocks +=
 695                         subdev[i]->ecc_stats.badblocks;
 696                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 697                     concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 698                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 699                     !concat->mtd._read_oob  != !subdev[i]->_read_oob ||
 700                     !concat->mtd._write_oob != !subdev[i]->_write_oob) {
 701                         kfree(concat);
 702                         printk("Incompatible OOB or ECC data on \"%s\"\n",
 703                                subdev[i]->name);
 704                         return NULL;
 705                 }
 706                 concat->subdev[i] = subdev[i];
 707
 708         }
 709
 710         mtd_set_ooblayout(&concat->mtd, subdev[0]->ooblayout);
 711
 712         concat->num_subdev = num_devs;
 713         concat->mtd.name = name;
 714
 715         concat->mtd._erase = concat_erase;
 716         concat->mtd._read = concat_read;
 717         concat->mtd._write = concat_write;
 718         concat->mtd._sync = concat_sync;
 719         concat->mtd._lock = concat_lock;
 720         concat->mtd._unlock = concat_unlock;
 721         concat->mtd._suspend = concat_suspend;
 722         concat->mtd._resume = concat_resume;
 723
 724         /*
 725          * Combine the erase block size info of the subdevices:
 726          *
 727          * first, walk the map of the new device and see how
 728          * many changes in erase size we have
 729          */
 730         max_erasesize = curr_erasesize = subdev[0]->erasesize;
 731         num_erase_region = 1;
 732         for (i = 0; i < num_devs; i++) {
 733                 if (subdev[i]->numeraseregions == 0) {
 734                         /* current subdevice has uniform erase size */
 735                         if (subdev[i]->erasesize != curr_erasesize) {
 736                                 /* if it differs from the last subdevice's erase size, count it */
 737                                 ++num_erase_region;
 738                                 curr_erasesize = subdev[i]->erasesize;
 739                                 if (curr_erasesize > max_erasesize)
 740                                         max_erasesize = curr_erasesize;
 741                         }
 742                 } else {
 743                         /* current subdevice has variable erase size */
 744                         int j;
 745                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
 746
 747                                 /* walk the list of erase regions, count any changes */
 748                                 if (subdev[i]->eraseregions[j].erasesize !=
 749                                     curr_erasesize) {
 750                                         ++num_erase_region;
 751                                         curr_erasesize =
 752                                             subdev[i]->eraseregions[j].
 753                                             erasesize;
 754                                         if (curr_erasesize > max_erasesize)
 755                                                 max_erasesize = curr_erasesize;
 756                                 }
 757                         }
 758                 }
 759         }
 760
 761         if (num_erase_region == 1) {
 762                 /*
 763                  * All subdevices have the same uniform erase size.
 764                  * This is easy:
 765                  */
 766                 concat->mtd.erasesize = curr_erasesize;
 767                 concat->mtd.numeraseregions = 0;
 768         } else {
 769                 uint64_t tmp64;
 770
 771                 /*
 772                  * erase block size varies across the subdevices: allocate
 773                  * space to store the data describing the variable erase regions
 774                  */
 775                 struct mtd_erase_region_info *erase_region_p;
 776                 uint64_t begin, position;
 777
 778                 concat->mtd.erasesize = max_erasesize;
 779                 concat->mtd.numeraseregions = num_erase_region;
 780                 concat->mtd.eraseregions = erase_region_p =
 781                     kmalloc_array(num_erase_region,
 782                                   sizeof(struct mtd_erase_region_info),
 783                                   GFP_KERNEL);
 784                 if (!erase_region_p) {
 785                         kfree(concat);
 786                         printk
 787                             ("memory allocation error while creating erase region list"
 788                              " for device \"%s\"\n", name);
 789                         return NULL;
 790                 }
 791
 792                 /*
 793                  * walk the map of the new device once more and fill in
 794                  * in erase region info:
 795                  */
 796                 curr_erasesize = subdev[0]->erasesize;
 797                 begin = position = 0;
 798                 for (i = 0; i < num_devs; i++) {
 799                         if (subdev[i]->numeraseregions == 0) {
 800                                 /* current subdevice has uniform erase size */
 801                                 if (subdev[i]->erasesize != curr_erasesize) {
 802                                         /*
 803                                          *  fill in an mtd_erase_region_info structure for the area
 804                                          *  we have walked so far:
 805                                          */
 806                                         erase_region_p->offset = begin;
 807                                         erase_region_p->erasesize =
 808                                             curr_erasesize;
 809                                         tmp64 = position - begin;
 810                                         do_div(tmp64, curr_erasesize);
 811                                         erase_region_p->numblocks = tmp64;
 812                                         begin = position;
 813
 814                                         curr_erasesize = subdev[i]->erasesize;
 815                                         ++erase_region_p;
 816                                 }
 817                                 position += subdev[i]->size;
 818                         } else {
 819                                 /* current subdevice has variable erase size */
 820                                 int j;
 821                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
 822                                         /* walk the list of erase regions, count any changes */
 823                                         if (subdev[i]->eraseregions[j].
 824                                             erasesize != curr_erasesize) {
 825                                                 erase_region_p->offset = begin;
 826                                                 erase_region_p->erasesize =
 827                                                     curr_erasesize;
 828                                                 tmp64 = position - begin;
 829                                                 do_div(tmp64, curr_erasesize);
 830                                                 erase_region_p->numblocks = tmp64;
 831                                                 begin = position;
 832
 833                                                 curr_erasesize =
 834                                                     subdev[i]->eraseregions[j].
 835                                                     erasesize;
 836                                                 ++erase_region_p;
 837                                         }
 838                                         position +=
 839                                             subdev[i]->eraseregions[j].
 840                                             numblocks * (uint64_t)curr_erasesize;
 841                                 }
 842                         }
 843                 }
 844                 /* Now write the final entry */
 845                 erase_region_p->offset = begin;
 846                 erase_region_p->erasesize = curr_erasesize;
 847                 tmp64 = position - begin;
 848                 do_div(tmp64, curr_erasesize);
 849                 erase_region_p->numblocks = tmp64;
 850         }
 851
 852         return &concat->mtd;
 853 }
 854
 855 /*
 856  * This function destroys an MTD object obtained from concat_mtd_devs()
 857  */
 858
 859 void mtd_concat_destroy(struct mtd_info *mtd)
 860 {
 861         struct mtd_concat *concat = CONCAT(mtd);
 862         if (concat->mtd.numeraseregions)
 863                 kfree(concat->mtd.eraseregions);
 864         kfree(concat);
 865 }
 866
 867 EXPORT_SYMBOL(mtd_concat_create);
 868 EXPORT_SYMBOL(mtd_concat_destroy);
 869
 870 MODULE_LICENSE("GPL");
 871 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 872 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");