linux/drivers/mtd/mtdconcat.c
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   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 */
  43struct 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
  67static int
  68concat_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
 119static int
 120concat_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
 157static int
 158concat_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
 232static int
 233concat_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
 289static int
 290concat_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.oobretlen;
 315                if (err)
 316                        return err;
 317
 318                if (devops.datbuf) {
 319                        devops.len = ops->len - ops->retlen;
 320                        if (!devops.len)
 321                                return 0;
 322                        devops.datbuf += devops.retlen;
 323                }
 324                if (devops.oobbuf) {
 325                        devops.ooblen = ops->ooblen - ops->oobretlen;
 326                        if (!devops.ooblen)
 327                                return 0;
 328                        devops.oobbuf += devops.oobretlen;
 329                }
 330                to = 0;
 331        }
 332        return -EINVAL;
 333}
 334
 335static void concat_erase_callback(struct erase_info *instr)
 336{
 337        wake_up((wait_queue_head_t *) instr->priv);
 338}
 339
 340static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
 341{
 342        int err;
 343        wait_queue_head_t waitq;
 344        DECLARE_WAITQUEUE(wait, current);
 345
 346        /*
 347         * This code was stol^H^H^H^Hinspired by mtdchar.c
 348         */
 349        init_waitqueue_head(&waitq);
 350
 351        erase->mtd = mtd;
 352        erase->callback = concat_erase_callback;
 353        erase->priv = (unsigned long) &waitq;
 354
 355        /*
 356         * FIXME: Allow INTERRUPTIBLE. Which means
 357         * not having the wait_queue head on the stack.
 358         */
 359        err = mtd_erase(mtd, erase);
 360        if (!err) {
 361                set_current_state(TASK_UNINTERRUPTIBLE);
 362                add_wait_queue(&waitq, &wait);
 363                if (erase->state != MTD_ERASE_DONE
 364                    && erase->state != MTD_ERASE_FAILED)
 365                        schedule();
 366                remove_wait_queue(&waitq, &wait);
 367                set_current_state(TASK_RUNNING);
 368
 369                err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
 370        }
 371        return err;
 372}
 373
 374static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
 375{
 376        struct mtd_concat *concat = CONCAT(mtd);
 377        struct mtd_info *subdev;
 378        int i, err;
 379        uint64_t length, offset = 0;
 380        struct erase_info *erase;
 381
 382        /*
 383         * Check for proper erase block alignment of the to-be-erased area.
 384         * It is easier to do this based on the super device's erase
 385         * region info rather than looking at each particular sub-device
 386         * in turn.
 387         */
 388        if (!concat->mtd.numeraseregions) {
 389                /* the easy case: device has uniform erase block size */
 390                if (instr->addr & (concat->mtd.erasesize - 1))
 391                        return -EINVAL;
 392                if (instr->len & (concat->mtd.erasesize - 1))
 393                        return -EINVAL;
 394        } else {
 395                /* device has variable erase size */
 396                struct mtd_erase_region_info *erase_regions =
 397                    concat->mtd.eraseregions;
 398
 399                /*
 400                 * Find the erase region where the to-be-erased area begins:
 401                 */
 402                for (i = 0; i < concat->mtd.numeraseregions &&
 403                     instr->addr >= erase_regions[i].offset; i++) ;
 404                --i;
 405
 406                /*
 407                 * Now erase_regions[i] is the region in which the
 408                 * to-be-erased area begins. Verify that the starting
 409                 * offset is aligned to this region's erase size:
 410                 */
 411                if (i < 0 || instr->addr & (erase_regions[i].erasesize - 1))
 412                        return -EINVAL;
 413
 414                /*
 415                 * now find the erase region where the to-be-erased area ends:
 416                 */
 417                for (; i < concat->mtd.numeraseregions &&
 418                     (instr->addr + instr->len) >= erase_regions[i].offset;
 419                     ++i) ;
 420                --i;
 421                /*
 422                 * check if the ending offset is aligned to this region's erase size
 423                 */
 424                if (i < 0 || ((instr->addr + instr->len) &
 425                                        (erase_regions[i].erasesize - 1)))
 426                        return -EINVAL;
 427        }
 428
 429        /* make a local copy of instr to avoid modifying the caller's struct */
 430        erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
 431
 432        if (!erase)
 433                return -ENOMEM;
 434
 435        *erase = *instr;
 436        length = instr->len;
 437
 438        /*
 439         * find the subdevice where the to-be-erased area begins, adjust
 440         * starting offset to be relative to the subdevice start
 441         */
 442        for (i = 0; i < concat->num_subdev; i++) {
 443                subdev = concat->subdev[i];
 444                if (subdev->size <= erase->addr) {
 445                        erase->addr -= subdev->size;
 446                        offset += subdev->size;
 447                } else {
 448                        break;
 449                }
 450        }
 451
 452        /* must never happen since size limit has been verified above */
 453        BUG_ON(i >= concat->num_subdev);
 454
 455        /* now do the erase: */
 456        err = 0;
 457        for (; length > 0; i++) {
 458                /* loop for all subdevices affected by this request */
 459                subdev = concat->subdev[i];     /* get current subdevice */
 460
 461                /* limit length to subdevice's size: */
 462                if (erase->addr + length > subdev->size)
 463                        erase->len = subdev->size - erase->addr;
 464                else
 465                        erase->len = length;
 466
 467                length -= erase->len;
 468                if ((err = concat_dev_erase(subdev, erase))) {
 469                        /* sanity check: should never happen since
 470                         * block alignment has been checked above */
 471                        BUG_ON(err == -EINVAL);
 472                        if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
 473                                instr->fail_addr = erase->fail_addr + offset;
 474                        break;
 475                }
 476                /*
 477                 * erase->addr specifies the offset of the area to be
 478                 * erased *within the current subdevice*. It can be
 479                 * non-zero only the first time through this loop, i.e.
 480                 * for the first subdevice where blocks need to be erased.
 481                 * All the following erases must begin at the start of the
 482                 * current subdevice, i.e. at offset zero.
 483                 */
 484                erase->addr = 0;
 485                offset += subdev->size;
 486        }
 487        instr->state = erase->state;
 488        kfree(erase);
 489        if (err)
 490                return err;
 491
 492        if (instr->callback)
 493                instr->callback(instr);
 494        return 0;
 495}
 496
 497static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 498{
 499        struct mtd_concat *concat = CONCAT(mtd);
 500        int i, err = -EINVAL;
 501
 502        for (i = 0; i < concat->num_subdev; i++) {
 503                struct mtd_info *subdev = concat->subdev[i];
 504                uint64_t size;
 505
 506                if (ofs >= subdev->size) {
 507                        size = 0;
 508                        ofs -= subdev->size;
 509                        continue;
 510                }
 511                if (ofs + len > subdev->size)
 512                        size = subdev->size - ofs;
 513                else
 514                        size = len;
 515
 516                err = mtd_lock(subdev, ofs, size);
 517                if (err)
 518                        break;
 519
 520                len -= size;
 521                if (len == 0)
 522                        break;
 523
 524                err = -EINVAL;
 525                ofs = 0;
 526        }
 527
 528        return err;
 529}
 530
 531static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 532{
 533        struct mtd_concat *concat = CONCAT(mtd);
 534        int i, err = 0;
 535
 536        for (i = 0; i < concat->num_subdev; i++) {
 537                struct mtd_info *subdev = concat->subdev[i];
 538                uint64_t size;
 539
 540                if (ofs >= subdev->size) {
 541                        size = 0;
 542                        ofs -= subdev->size;
 543                        continue;
 544                }
 545                if (ofs + len > subdev->size)
 546                        size = subdev->size - ofs;
 547                else
 548                        size = len;
 549
 550                err = mtd_unlock(subdev, ofs, size);
 551                if (err)
 552                        break;
 553
 554                len -= size;
 555                if (len == 0)
 556                        break;
 557
 558                err = -EINVAL;
 559                ofs = 0;
 560        }
 561
 562        return err;
 563}
 564
 565static void concat_sync(struct mtd_info *mtd)
 566{
 567        struct mtd_concat *concat = CONCAT(mtd);
 568        int i;
 569
 570        for (i = 0; i < concat->num_subdev; i++) {
 571                struct mtd_info *subdev = concat->subdev[i];
 572                mtd_sync(subdev);
 573        }
 574}
 575
 576static int concat_suspend(struct mtd_info *mtd)
 577{
 578        struct mtd_concat *concat = CONCAT(mtd);
 579        int i, rc = 0;
 580
 581        for (i = 0; i < concat->num_subdev; i++) {
 582                struct mtd_info *subdev = concat->subdev[i];
 583                if ((rc = mtd_suspend(subdev)) < 0)
 584                        return rc;
 585        }
 586        return rc;
 587}
 588
 589static void concat_resume(struct mtd_info *mtd)
 590{
 591        struct mtd_concat *concat = CONCAT(mtd);
 592        int i;
 593
 594        for (i = 0; i < concat->num_subdev; i++) {
 595                struct mtd_info *subdev = concat->subdev[i];
 596                mtd_resume(subdev);
 597        }
 598}
 599
 600static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
 601{
 602        struct mtd_concat *concat = CONCAT(mtd);
 603        int i, res = 0;
 604
 605        if (!mtd_can_have_bb(concat->subdev[0]))
 606                return res;
 607
 608        for (i = 0; i < concat->num_subdev; i++) {
 609                struct mtd_info *subdev = concat->subdev[i];
 610
 611                if (ofs >= subdev->size) {
 612                        ofs -= subdev->size;
 613                        continue;
 614                }
 615
 616                res = mtd_block_isbad(subdev, ofs);
 617                break;
 618        }
 619
 620        return res;
 621}
 622
 623static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 624{
 625        struct mtd_concat *concat = CONCAT(mtd);
 626        int i, err = -EINVAL;
 627
 628        for (i = 0; i < concat->num_subdev; i++) {
 629                struct mtd_info *subdev = concat->subdev[i];
 630
 631                if (ofs >= subdev->size) {
 632                        ofs -= subdev->size;
 633                        continue;
 634                }
 635
 636                err = mtd_block_markbad(subdev, ofs);
 637                if (!err)
 638                        mtd->ecc_stats.badblocks++;
 639                break;
 640        }
 641
 642        return err;
 643}
 644
 645/*
 646 * try to support NOMMU mmaps on concatenated devices
 647 * - we don't support subdev spanning as we can't guarantee it'll work
 648 */
 649static unsigned long concat_get_unmapped_area(struct mtd_info *mtd,
 650                                              unsigned long len,
 651                                              unsigned long offset,
 652                                              unsigned long flags)
 653{
 654        struct mtd_concat *concat = CONCAT(mtd);
 655        int i;
 656
 657        for (i = 0; i < concat->num_subdev; i++) {
 658                struct mtd_info *subdev = concat->subdev[i];
 659
 660                if (offset >= subdev->size) {
 661                        offset -= subdev->size;
 662                        continue;
 663                }
 664
 665                return mtd_get_unmapped_area(subdev, len, offset, flags);
 666        }
 667
 668        return (unsigned long) -ENOSYS;
 669}
 670
 671/*
 672 * This function constructs a virtual MTD device by concatenating
 673 * num_devs MTD devices. A pointer to the new device object is
 674 * stored to *new_dev upon success. This function does _not_
 675 * register any devices: this is the caller's responsibility.
 676 */
 677struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
 678                                   int num_devs,        /* number of subdevices      */
 679                                   const char *name)
 680{                               /* name for the new device   */
 681        int i;
 682        size_t size;
 683        struct mtd_concat *concat;
 684        uint32_t max_erasesize, curr_erasesize;
 685        int num_erase_region;
 686        int max_writebufsize = 0;
 687
 688        printk(KERN_NOTICE "Concatenating MTD devices:\n");
 689        for (i = 0; i < num_devs; i++)
 690                printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
 691        printk(KERN_NOTICE "into device \"%s\"\n", name);
 692
 693        /* allocate the device structure */
 694        size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
 695        concat = kzalloc(size, GFP_KERNEL);
 696        if (!concat) {
 697                printk
 698                    ("memory allocation error while creating concatenated device \"%s\"\n",
 699                     name);
 700                return NULL;
 701        }
 702        concat->subdev = (struct mtd_info **) (concat + 1);
 703
 704        /*
 705         * Set up the new "super" device's MTD object structure, check for
 706         * incompatibilities between the subdevices.
 707         */
 708        concat->mtd.type = subdev[0]->type;
 709        concat->mtd.flags = subdev[0]->flags;
 710        concat->mtd.size = subdev[0]->size;
 711        concat->mtd.erasesize = subdev[0]->erasesize;
 712        concat->mtd.writesize = subdev[0]->writesize;
 713
 714        for (i = 0; i < num_devs; i++)
 715                if (max_writebufsize < subdev[i]->writebufsize)
 716                        max_writebufsize = subdev[i]->writebufsize;
 717        concat->mtd.writebufsize = max_writebufsize;
 718
 719        concat->mtd.subpage_sft = subdev[0]->subpage_sft;
 720        concat->mtd.oobsize = subdev[0]->oobsize;
 721        concat->mtd.oobavail = subdev[0]->oobavail;
 722        if (subdev[0]->_writev)
 723                concat->mtd._writev = concat_writev;
 724        if (subdev[0]->_read_oob)
 725                concat->mtd._read_oob = concat_read_oob;
 726        if (subdev[0]->_write_oob)
 727                concat->mtd._write_oob = concat_write_oob;
 728        if (subdev[0]->_block_isbad)
 729                concat->mtd._block_isbad = concat_block_isbad;
 730        if (subdev[0]->_block_markbad)
 731                concat->mtd._block_markbad = concat_block_markbad;
 732
 733        concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 734
 735        concat->mtd.backing_dev_info = subdev[0]->backing_dev_info;
 736
 737        concat->subdev[0] = subdev[0];
 738
 739        for (i = 1; i < num_devs; i++) {
 740                if (concat->mtd.type != subdev[i]->type) {
 741                        kfree(concat);
 742                        printk("Incompatible device type on \"%s\"\n",
 743                               subdev[i]->name);
 744                        return NULL;
 745                }
 746                if (concat->mtd.flags != subdev[i]->flags) {
 747                        /*
 748                         * Expect all flags except MTD_WRITEABLE to be
 749                         * equal on all subdevices.
 750                         */
 751                        if ((concat->mtd.flags ^ subdev[i]->
 752                             flags) & ~MTD_WRITEABLE) {
 753                                kfree(concat);
 754                                printk("Incompatible device flags on \"%s\"\n",
 755                                       subdev[i]->name);
 756                                return NULL;
 757                        } else
 758                                /* if writeable attribute differs,
 759                                   make super device writeable */
 760                                concat->mtd.flags |=
 761                                    subdev[i]->flags & MTD_WRITEABLE;
 762                }
 763
 764                /* only permit direct mapping if the BDIs are all the same
 765                 * - copy-mapping is still permitted
 766                 */
 767                if (concat->mtd.backing_dev_info !=
 768                    subdev[i]->backing_dev_info)
 769                        concat->mtd.backing_dev_info =
 770                                &default_backing_dev_info;
 771
 772                concat->mtd.size += subdev[i]->size;
 773                concat->mtd.ecc_stats.badblocks +=
 774                        subdev[i]->ecc_stats.badblocks;
 775                if (concat->mtd.writesize   !=  subdev[i]->writesize ||
 776                    concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
 777                    concat->mtd.oobsize    !=  subdev[i]->oobsize ||
 778                    !concat->mtd._read_oob  != !subdev[i]->_read_oob ||
 779                    !concat->mtd._write_oob != !subdev[i]->_write_oob) {
 780                        kfree(concat);
 781                        printk("Incompatible OOB or ECC data on \"%s\"\n",
 782                               subdev[i]->name);
 783                        return NULL;
 784                }
 785                concat->subdev[i] = subdev[i];
 786
 787        }
 788
 789        concat->mtd.ecclayout = subdev[0]->ecclayout;
 790
 791        concat->num_subdev = num_devs;
 792        concat->mtd.name = name;
 793
 794        concat->mtd._erase = concat_erase;
 795        concat->mtd._read = concat_read;
 796        concat->mtd._write = concat_write;
 797        concat->mtd._sync = concat_sync;
 798        concat->mtd._lock = concat_lock;
 799        concat->mtd._unlock = concat_unlock;
 800        concat->mtd._suspend = concat_suspend;
 801        concat->mtd._resume = concat_resume;
 802        concat->mtd._get_unmapped_area = concat_get_unmapped_area;
 803
 804        /*
 805         * Combine the erase block size info of the subdevices:
 806         *
 807         * first, walk the map of the new device and see how
 808         * many changes in erase size we have
 809         */
 810        max_erasesize = curr_erasesize = subdev[0]->erasesize;
 811        num_erase_region = 1;
 812        for (i = 0; i < num_devs; i++) {
 813                if (subdev[i]->numeraseregions == 0) {
 814                        /* current subdevice has uniform erase size */
 815                        if (subdev[i]->erasesize != curr_erasesize) {
 816                                /* if it differs from the last subdevice's erase size, count it */
 817                                ++num_erase_region;
 818                                curr_erasesize = subdev[i]->erasesize;
 819                                if (curr_erasesize > max_erasesize)
 820                                        max_erasesize = curr_erasesize;
 821                        }
 822                } else {
 823                        /* current subdevice has variable erase size */
 824                        int j;
 825                        for (j = 0; j < subdev[i]->numeraseregions; j++) {
 826
 827                                /* walk the list of erase regions, count any changes */
 828                                if (subdev[i]->eraseregions[j].erasesize !=
 829                                    curr_erasesize) {
 830                                        ++num_erase_region;
 831                                        curr_erasesize =
 832                                            subdev[i]->eraseregions[j].
 833                                            erasesize;
 834                                        if (curr_erasesize > max_erasesize)
 835                                                max_erasesize = curr_erasesize;
 836                                }
 837                        }
 838                }
 839        }
 840
 841        if (num_erase_region == 1) {
 842                /*
 843                 * All subdevices have the same uniform erase size.
 844                 * This is easy:
 845                 */
 846                concat->mtd.erasesize = curr_erasesize;
 847                concat->mtd.numeraseregions = 0;
 848        } else {
 849                uint64_t tmp64;
 850
 851                /*
 852                 * erase block size varies across the subdevices: allocate
 853                 * space to store the data describing the variable erase regions
 854                 */
 855                struct mtd_erase_region_info *erase_region_p;
 856                uint64_t begin, position;
 857
 858                concat->mtd.erasesize = max_erasesize;
 859                concat->mtd.numeraseregions = num_erase_region;
 860                concat->mtd.eraseregions = erase_region_p =
 861                    kmalloc(num_erase_region *
 862                            sizeof (struct mtd_erase_region_info), GFP_KERNEL);
 863                if (!erase_region_p) {
 864                        kfree(concat);
 865                        printk
 866                            ("memory allocation error while creating erase region list"
 867                             " for device \"%s\"\n", name);
 868                        return NULL;
 869                }
 870
 871                /*
 872                 * walk the map of the new device once more and fill in
 873                 * in erase region info:
 874                 */
 875                curr_erasesize = subdev[0]->erasesize;
 876                begin = position = 0;
 877                for (i = 0; i < num_devs; i++) {
 878                        if (subdev[i]->numeraseregions == 0) {
 879                                /* current subdevice has uniform erase size */
 880                                if (subdev[i]->erasesize != curr_erasesize) {
 881                                        /*
 882                                         *  fill in an mtd_erase_region_info structure for the area
 883                                         *  we have walked so far:
 884                                         */
 885                                        erase_region_p->offset = begin;
 886                                        erase_region_p->erasesize =
 887                                            curr_erasesize;
 888                                        tmp64 = position - begin;
 889                                        do_div(tmp64, curr_erasesize);
 890                                        erase_region_p->numblocks = tmp64;
 891                                        begin = position;
 892
 893                                        curr_erasesize = subdev[i]->erasesize;
 894                                        ++erase_region_p;
 895                                }
 896                                position += subdev[i]->size;
 897                        } else {
 898                                /* current subdevice has variable erase size */
 899                                int j;
 900                                for (j = 0; j < subdev[i]->numeraseregions; j++) {
 901                                        /* walk the list of erase regions, count any changes */
 902                                        if (subdev[i]->eraseregions[j].
 903                                            erasesize != curr_erasesize) {
 904                                                erase_region_p->offset = begin;
 905                                                erase_region_p->erasesize =
 906                                                    curr_erasesize;
 907                                                tmp64 = position - begin;
 908                                                do_div(tmp64, curr_erasesize);
 909                                                erase_region_p->numblocks = tmp64;
 910                                                begin = position;
 911
 912                                                curr_erasesize =
 913                                                    subdev[i]->eraseregions[j].
 914                                                    erasesize;
 915                                                ++erase_region_p;
 916                                        }
 917                                        position +=
 918                                            subdev[i]->eraseregions[j].
 919                                            numblocks * (uint64_t)curr_erasesize;
 920                                }
 921                        }
 922                }
 923                /* Now write the final entry */
 924                erase_region_p->offset = begin;
 925                erase_region_p->erasesize = curr_erasesize;
 926                tmp64 = position - begin;
 927                do_div(tmp64, curr_erasesize);
 928                erase_region_p->numblocks = tmp64;
 929        }
 930
 931        return &concat->mtd;
 932}
 933
 934/*
 935 * This function destroys an MTD object obtained from concat_mtd_devs()
 936 */
 937
 938void mtd_concat_destroy(struct mtd_info *mtd)
 939{
 940        struct mtd_concat *concat = CONCAT(mtd);
 941        if (concat->mtd.numeraseregions)
 942                kfree(concat->mtd.eraseregions);
 943        kfree(concat);
 944}
 945
 946EXPORT_SYMBOL(mtd_concat_create);
 947EXPORT_SYMBOL(mtd_concat_destroy);
 948
 949MODULE_LICENSE("GPL");
 950MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
 951MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");
 952
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