linux/drivers/mtd/mtdconcat.c
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   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 */
  29struct 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
  53static int
  54concat_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
 105static int
 106concat_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
 143static int
 144concat_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
 218static int
 219concat_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
 275static int
 276concat_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
 322static 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
 440static int concat_xxlock(struct mtd_info *mtd, loff_t ofs, uint64_t len,
 441                         bool is_lock)
 442{
 443        struct mtd_concat *concat = CONCAT(mtd);
 444        int i, err = -EINVAL;
 445
 446        for (i = 0; i < concat->num_subdev; i++) {
 447                struct mtd_info *subdev = concat->subdev[i];
 448                uint64_t size;
 449
 450                if (ofs >= subdev->size) {
 451                        size = 0;
 452                        ofs -= subdev->size;
 453                        continue;
 454                }
 455                if (ofs + len > subdev->size)
 456                        size = subdev->size - ofs;
 457                else
 458                        size = len;
 459
 460                if (is_lock)
 461                        err = mtd_lock(subdev, ofs, size);
 462                else
 463                        err = mtd_unlock(subdev, ofs, size);
 464                if (err)
 465                        break;
 466
 467                len -= size;
 468                if (len == 0)
 469                        break;
 470
 471                err = -EINVAL;
 472                ofs = 0;
 473        }
 474
 475        return err;
 476}
 477
 478static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 479{
 480        return concat_xxlock(mtd, ofs, len, true);
 481}
 482
 483static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 484{
 485        return concat_xxlock(mtd, ofs, len, false);
 486}
 487
 488static int concat_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 489{
 490        struct mtd_concat *concat = CONCAT(mtd);
 491        int i, err = -EINVAL;
 492
 493        for (i = 0; i < concat->num_subdev; i++) {
 494                struct mtd_info *subdev = concat->subdev[i];
 495
 496                if (ofs >= subdev->size) {
 497                        ofs -= subdev->size;
 498                        continue;
 499                }
 500
 501                if (ofs + len > subdev->size)
 502                        break;
 503
 504                return mtd_is_locked(subdev, ofs, len);
 505        }
 506
 507        return err;
 508}
 509
 510static void concat_sync(struct mtd_info *mtd)
 511{
 512        struct mtd_concat *concat = CONCAT(mtd);
 513        int i;
 514
 515        for (i = 0; i < concat->num_subdev; i++) {
 516                struct mtd_info *subdev = concat->subdev[i];
 517                mtd_sync(subdev);
 518        }
 519}
 520
 521static int concat_suspend(struct mtd_info *mtd)
 522{
 523        struct mtd_concat *concat = CONCAT(mtd);
 524        int i, rc = 0;
 525
 526        for (i = 0; i < concat->num_subdev; i++) {
 527                struct mtd_info *subdev = concat->subdev[i];
 528                if ((rc = mtd_suspend(subdev)) < 0)
 529                        return rc;
 530        }
 531        return rc;
 532}
 533
 534static void concat_resume(struct mtd_info *mtd)
 535{
 536        struct mtd_concat *concat = CONCAT(mtd);
 537        int i;
 538
 539        for (i = 0; i < concat->num_subdev; i++) {
 540                struct mtd_info *subdev = concat->subdev[i];
 541                mtd_resume(subdev);
 542        }
 543}
 544
 545static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 546{
 547        struct mtd_concat *concat = CONCAT(mtd);
 548        int i, res = 0;
 549
 550        if (!mtd_can_have_bb(concat->subdev[0]))
 551                return res;
 552
 553        for (i = 0; i < concat->num_subdev; i++) {
 554                struct mtd_info *subdev = concat->subdev[i];
 555
 556                if (ofs >= subdev->size) {
 557                        ofs -= subdev->size;
 558                        continue;
 559                }
 560
 561                res = mtd_block_isbad(subdev, ofs);
 562                break;
 563        }
 564
 565        return res;
 566}
 567
 568static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 569{
 570        struct mtd_concat *concat = CONCAT(mtd);
 571        int i, err = -EINVAL;
 572
 573        for (i = 0; i < concat->num_subdev; i++) {
 574                struct mtd_info *subdev = concat->subdev[i];
 575
 576                if (ofs >= subdev->size) {
 577                        ofs -= subdev->size;
 578                        continue;
 579                }
 580
 581                err = mtd_block_markbad(subdev, ofs);
 582                if (!err)
 583                        mtd->ecc_stats.badblocks++;
 584                break;
 585        }
 586
 587        return err;
 588}
 589
 590/*
 591 * This function constructs a virtual MTD device by concatenating
 592 * num_devs MTD devices. A pointer to the new device object is
 593 * stored to *new_dev upon success. This function does _not_
 594 * register any devices: this is the caller's responsibility.
 595 */
 596struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 597                                   int num_devs,        /* number of subdevices      */
 598                                   const char *name)
 599{                               /* name for the new device   */
 600        int i;
 601        size_t size;
 602        struct mtd_concat *concat;
 603        uint32_t max_erasesize, curr_erasesize;
 604        int num_erase_region;
 605        int max_writebufsize = 0;
 606
 607        printk(KERN_NOTICE "Concatenating MTD devices:\n");
 608        for (i = 0; i < num_devs; i++)
 609                printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 610        printk(KERN_NOTICE "into device \"%s\"\n", name);
 611
 612        /* allocate the device structure */
 613        size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 614        concat = kzalloc(size, GFP_KERNEL);
 615        if (!concat) {
 616                printk
 617                    ("memory allocation error while creating concatenated device \"%s\"\n",
 618                     name);
 619                return NULL;
 620        }
 621        concat->subdev = (struct mtd_info **) (concat + 1);
 622
 623        /*
 624         * Set up the new "super" device's MTD object structure, check for
 625         * incompatibilities between the subdevices.
 626         */
 627        concat->mtd.type = subdev[0]->type;
 628        concat->mtd.flags = subdev[0]->flags;
 629        concat->mtd.size = subdev[0]->size;
 630        concat->mtd.erasesize = subdev[0]->erasesize;
 631        concat->mtd.writesize = subdev[0]->writesize;
 632
 633        for (i = 0; i < num_devs; i++)
 634                if (max_writebufsize < subdev[i]->writebufsize)
 635                        max_writebufsize = subdev[i]->writebufsize;
 636        concat->mtd.writebufsize = max_writebufsize;
 637
 638        concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 639        concat->mtd.oobsize = subdev[0]->oobsize;
 640        concat->mtd.oobavail = subdev[0]->oobavail;
 641        if (subdev[0]->_writev)
 642                concat->mtd._writev = concat_writev;
 643        if (subdev[0]->_read_oob)
 644                concat->mtd._read_oob = concat_read_oob;
 645        if (subdev[0]->_write_oob)
 646                concat->mtd._write_oob = concat_write_oob;
 647        if (subdev[0]->_block_isbad)
 648                concat->mtd._block_isbad = concat_block_isbad;
 649        if (subdev[0]->_block_markbad)
 650                concat->mtd._block_markbad = concat_block_markbad;
 651
 652        concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 653
 654        concat->subdev[0] = subdev[0];
 655
 656        for (i = 1; i < num_devs; i++) {
 657                if (concat->mtd.type != subdev[i]->type) {
 658                        kfree(concat);
 659                        printk("Incompatible device type on \"%s\"\n",
 660                               subdev[i]->name);
 661                        return NULL;
 662                }
 663                if (concat->mtd.flags != subdev[i]->flags) {
 664                        /*
 665                         * Expect all flags except MTD_WRITEABLE to be
 666                         * equal on all subdevices.
 667                         */
 668                        if ((concat->mtd.flags ^ subdev[i]->
 669                             flags) & ~MTD_WRITEABLE) {
 670                                kfree(concat);
 671                                printk("Incompatible device flags on \"%s\"\n",
 672                                       subdev[i]->name);
 673                                return NULL;
 674                        } else
 675                                /* if writeable attribute differs,
 676                                   make super device writeable */
 677                                concat->mtd.flags |=
 678                                    subdev[i]->flags & MTD_WRITEABLE;
 679                }
 680
 681                concat->mtd.size += subdev[i]->size;
 682                concat->mtd.ecc_stats.badblocks +=
 683                        subdev[i]->ecc_stats.badblocks;
 684                if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 685                    concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 686                    concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 687                    !concat->mtd._read_oob  != !subdev[i]->_read_oob ||
 688                    !concat->mtd._write_oob != !subdev[i]->_write_oob) {
 689                        kfree(concat);
 690                        printk("Incompatible OOB or ECC data on \"%s\"\n",
 691                               subdev[i]->name);
 692                        return NULL;
 693                }
 694                concat->subdev[i] = subdev[i];
 695
 696        }
 697
 698        mtd_set_ooblayout(&concat->mtd, subdev[0]->ooblayout);
 699
 700        concat->num_subdev = num_devs;
 701        concat->mtd.name = name;
 702
 703        concat->mtd._erase = concat_erase;
 704        concat->mtd._read = concat_read;
 705        concat->mtd._write = concat_write;
 706        concat->mtd._sync = concat_sync;
 707        concat->mtd._lock = concat_lock;
 708        concat->mtd._unlock = concat_unlock;
 709        concat->mtd._is_locked = concat_is_locked;
 710        concat->mtd._suspend = concat_suspend;
 711        concat->mtd._resume = concat_resume;
 712
 713        /*
 714         * Combine the erase block size info of the subdevices:
 715         *
 716         * first, walk the map of the new device and see how
 717         * many changes in erase size we have
 718         */
 719        max_erasesize = curr_erasesize = subdev[0]->erasesize;
 720        num_erase_region = 1;
 721        for (i = 0; i < num_devs; i++) {
 722                if (subdev[i]->numeraseregions == 0) {
 723                        /* current subdevice has uniform erase size */
 724                        if (subdev[i]->erasesize != curr_erasesize) {
 725                                /* if it differs from the last subdevice's erase size, count it */
 726                                ++num_erase_region;
 727                                curr_erasesize = subdev[i]->erasesize;
 728                                if (curr_erasesize > max_erasesize)
 729                                        max_erasesize = curr_erasesize;
 730                        }
 731                } else {
 732                        /* current subdevice has variable erase size */
 733                        int j;
 734                        for (j = 0; j < subdev[i]->numeraseregions; j++) {
 735
 736                                /* walk the list of erase regions, count any changes */
 737                                if (subdev[i]->eraseregions[j].erasesize !=
 738                                    curr_erasesize) {
 739                                        ++num_erase_region;
 740                                        curr_erasesize =
 741                                            subdev[i]->eraseregions[j].
 742                                            erasesize;
 743                                        if (curr_erasesize > max_erasesize)
 744                                                max_erasesize = curr_erasesize;
 745                                }
 746                        }
 747                }
 748        }
 749
 750        if (num_erase_region == 1) {
 751                /*
 752                 * All subdevices have the same uniform erase size.
 753                 * This is easy:
 754                 */
 755                concat->mtd.erasesize = curr_erasesize;
 756                concat->mtd.numeraseregions = 0;
 757        } else {
 758                uint64_t tmp64;
 759
 760                /*
 761                 * erase block size varies across the subdevices: allocate
 762                 * space to store the data describing the variable erase regions
 763                 */
 764                struct mtd_erase_region_info *erase_region_p;
 765                uint64_t begin, position;
 766
 767                concat->mtd.erasesize = max_erasesize;
 768                concat->mtd.numeraseregions = num_erase_region;
 769                concat->mtd.eraseregions = erase_region_p =
 770                    kmalloc_array(num_erase_region,
 771                                  sizeof(struct mtd_erase_region_info),
 772                                  GFP_KERNEL);
 773                if (!erase_region_p) {
 774                        kfree(concat);
 775                        printk
 776                            ("memory allocation error while creating erase region list"
 777                             " for device \"%s\"\n", name);
 778                        return NULL;
 779                }
 780
 781                /*
 782                 * walk the map of the new device once more and fill in
 783                 * in erase region info:
 784                 */
 785                curr_erasesize = subdev[0]->erasesize;
 786                begin = position = 0;
 787                for (i = 0; i < num_devs; i++) {
 788                        if (subdev[i]->numeraseregions == 0) {
 789                                /* current subdevice has uniform erase size */
 790                                if (subdev[i]->erasesize != curr_erasesize) {
 791                                        /*
 792                                         *  fill in an mtd_erase_region_info structure for the area
 793                                         *  we have walked so far:
 794                                         */
 795                                        erase_region_p->offset = begin;
 796                                        erase_region_p->erasesize =
 797                                            curr_erasesize;
 798                                        tmp64 = position - begin;
 799                                        do_div(tmp64, curr_erasesize);
 800                                        erase_region_p->numblocks = tmp64;
 801                                        begin = position;
 802
 803                                        curr_erasesize = subdev[i]->erasesize;
 804                                        ++erase_region_p;
 805                                }
 806                                position += subdev[i]->size;
 807                        } else {
 808                                /* current subdevice has variable erase size */
 809                                int j;
 810                                for (j = 0; j < subdev[i]->numeraseregions; j++) {
 811                                        /* walk the list of erase regions, count any changes */
 812                                        if (subdev[i]->eraseregions[j].
 813                                            erasesize != curr_erasesize) {
 814                                                erase_region_p->offset = begin;
 815                                                erase_region_p->erasesize =
 816                                                    curr_erasesize;
 817                                                tmp64 = position - begin;
 818                                                do_div(tmp64, curr_erasesize);
 819                                                erase_region_p->numblocks = tmp64;
 820                                                begin = position;
 821
 822                                                curr_erasesize =
 823                                                    subdev[i]->eraseregions[j].
 824                                                    erasesize;
 825                                                ++erase_region_p;
 826                                        }
 827                                        position +=
 828                                            subdev[i]->eraseregions[j].
 829                                            numblocks * (uint64_t)curr_erasesize;
 830                                }
 831                        }
 832                }
 833                /* Now write the final entry */
 834                erase_region_p->offset = begin;
 835                erase_region_p->erasesize = curr_erasesize;
 836                tmp64 = position - begin;
 837                do_div(tmp64, curr_erasesize);
 838                erase_region_p->numblocks = tmp64;
 839        }
 840
 841        return &concat->mtd;
 842}
 843
 844/*
 845 * This function destroys an MTD object obtained from concat_mtd_devs()
 846 */
 847
 848void mtd_concat_destroy(struct mtd_info *mtd)
 849{
 850        struct mtd_concat *concat = CONCAT(mtd);
 851        if (concat->mtd.numeraseregions)
 852                kfree(concat->mtd.eraseregions);
 853        kfree(concat);
 854}
 855
 856EXPORT_SYMBOL(mtd_concat_create);
 857EXPORT_SYMBOL(mtd_concat_destroy);
 858
 859MODULE_LICENSE("GPL");
 860MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 861MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");
 862