drivers/mtd/nand/nand_util.c

   1 /*
   2  * drivers/mtd/nand/nand_util.c
   3  *
   4  * Copyright (C) 2006 by Weiss-Electronic GmbH.
   5  * All rights reserved.
   6  *
   7  * @author:     Guido Classen <clagix@gmail.com>
   8  * @descr:      NAND Flash support
   9  * @references: borrowed heavily from Linux mtd-utils code:
  10  *              flash_eraseall.c by Arcom Control System Ltd
  11  *              nandwrite.c by Steven J. Hill (sjhill@realitydiluted.com)
  12  *                             and Thomas Gleixner (tglx@linutronix.de)
  13  *
  14  * Copyright (C) 2008 Nokia Corporation: drop_ffs() function by
  15  * Artem Bityutskiy <dedekind1@gmail.com> from mtd-utils
  16  *
  17  * See file CREDITS for list of people who contributed to this
  18  * project.
  19  *
  20  * This program is free software; you can redistribute it and/or
  21  * modify it under the terms of the GNU General Public License version
  22  * 2 as published by the Free Software Foundation.
  23  *
  24  * This program is distributed in the hope that it will be useful,
  25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  * GNU General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with this program; if not, write to the Free Software
  31  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  32  * MA 02111-1307 USA
  33  *
  34  * Copyright 2010 Freescale Semiconductor
  35  * The portions of this file whose copyright is held by Freescale and which
  36  * are not considered a derived work of GPL v2-only code may be distributed
  37  * and/or modified under the terms of the GNU General Public License as
  38  * published by the Free Software Foundation; either version 2 of the
  39  * License, or (at your option) any later version.
  40  */
  41
  42 #include <common.h>
  43 #include <command.h>
  44 #include <watchdog.h>
  45 #include <malloc.h>
  46 #include <div64.h>
  47
  48 #include <asm/errno.h>
  49 #include <linux/mtd/mtd.h>
  50 #include <nand.h>
  51 #include <jffs2/jffs2.h>
  52
  53 typedef struct erase_info erase_info_t;
  54 typedef struct mtd_info   mtd_info_t;
  55
  56 /* support only for native endian JFFS2 */
  57 #define cpu_to_je16(x) (x)
  58 #define cpu_to_je32(x) (x)
  59
  60 /*****************************************************************************/
  61 static int nand_block_bad_scrub(struct mtd_info *mtd, loff_t ofs, int getchip)
  62 {
  63         return 0;
  64 }
  65
  66 /**
  67  * nand_erase_opts: - erase NAND flash with support for various options
  68  *                    (jffs2 formating)
  69  *
  70  * @param meminfo       NAND device to erase
  71  * @param opts          options,  @see struct nand_erase_options
  72  * @return              0 in case of success
  73  *
  74  * This code is ported from flash_eraseall.c from Linux mtd utils by
  75  * Arcom Control System Ltd.
  76  */
  77 int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
  78 {
  79         struct jffs2_unknown_node cleanmarker;
  80         erase_info_t erase;
  81         unsigned long erase_length, erased_length; /* in blocks */
  82         int bbtest = 1;
  83         int result;
  84         int percent_complete = -1;
  85         int (*nand_block_bad_old)(struct mtd_info *, loff_t, int) = NULL;
  86         const char *mtd_device = meminfo->name;
  87         struct mtd_oob_ops oob_opts;
  88         struct nand_chip *chip = meminfo->priv;
  89
  90         if ((opts->offset & (meminfo->writesize - 1)) != 0) {
  91                 printf("Attempt to erase non page aligned data\n");
  92                 return -1;
  93         }
  94
  95         memset(&erase, 0, sizeof(erase));
  96         memset(&oob_opts, 0, sizeof(oob_opts));
  97
  98         erase.mtd = meminfo;
  99         erase.len  = meminfo->erasesize;
 100         erase.addr = opts->offset;
 101         erase_length = lldiv(opts->length + meminfo->erasesize - 1,
 102                              meminfo->erasesize);
 103
 104         cleanmarker.magic = cpu_to_je16 (JFFS2_MAGIC_BITMASK);
 105         cleanmarker.nodetype = cpu_to_je16 (JFFS2_NODETYPE_CLEANMARKER);
 106         cleanmarker.totlen = cpu_to_je32(8);
 107
 108         /* scrub option allows to erase badblock. To prevent internal
 109          * check from erase() method, set block check method to dummy
 110          * and disable bad block table while erasing.
 111          */
 112         if (opts->scrub) {
 113                 struct nand_chip *priv_nand = meminfo->priv;
 114
 115                 nand_block_bad_old = priv_nand->block_bad;
 116                 priv_nand->block_bad = nand_block_bad_scrub;
 117                 /* we don't need the bad block table anymore...
 118                  * after scrub, there are no bad blocks left!
 119                  */
 120                 if (priv_nand->bbt) {
 121                         kfree(priv_nand->bbt);
 122                 }
 123                 priv_nand->bbt = NULL;
 124         }
 125
 126         for (erased_length = 0;
 127              erased_length < erase_length;
 128              erase.addr += meminfo->erasesize) {
 129
 130                 WATCHDOG_RESET ();
 131
 132                 if (!opts->scrub && bbtest) {
 133                         int ret = meminfo->block_isbad(meminfo, erase.addr);
 134                         if (ret > 0) {
 135                                 if (!opts->quiet)
 136                                         printf("\rSkipping bad block at  "
 137                                                "0x%08llx                 "
 138                                                "                         \n",
 139                                                erase.addr);
 140
 141                                 if (!opts->spread)
 142                                         erased_length++;
 143
 144                                 continue;
 145
 146                         } else if (ret < 0) {
 147                                 printf("\n%s: MTD get bad block failed: %d\n",
 148                                        mtd_device,
 149                                        ret);
 150                                 return -1;
 151                         }
 152                 }
 153
 154                 erased_length++;
 155
 156                 result = meminfo->erase(meminfo, &erase);
 157                 if (result != 0) {
 158                         printf("\n%s: MTD Erase failure: %d\n",
 159                                mtd_device, result);
 160                         continue;
 161                 }
 162
 163                 /* format for JFFS2 ? */
 164                 if (opts->jffs2 && chip->ecc.layout->oobavail >= 8) {
 165                         chip->ops.ooblen = 8;
 166                         chip->ops.datbuf = NULL;
 167                         chip->ops.oobbuf = (uint8_t *)&cleanmarker;
 168                         chip->ops.ooboffs = 0;
 169                         chip->ops.mode = MTD_OOB_AUTO;
 170
 171                         result = meminfo->write_oob(meminfo,
 172                                                     erase.addr,
 173                                                     &chip->ops);
 174                         if (result != 0) {
 175                                 printf("\n%s: MTD writeoob failure: %d\n",
 176                                        mtd_device, result);
 177                                 continue;
 178                         }
 179                 }
 180
 181                 if (!opts->quiet) {
 182                         unsigned long long n = erased_length * 100ULL;
 183                         int percent;
 184
 185                         do_div(n, erase_length);
 186                         percent = (int)n;
 187
 188                         /* output progress message only at whole percent
 189                          * steps to reduce the number of messages printed
 190                          * on (slow) serial consoles
 191                          */
 192                         if (percent != percent_complete) {
 193                                 percent_complete = percent;
 194
 195                                 printf("\rErasing at 0x%llx -- %3d%% complete.",
 196                                        erase.addr, percent);
 197
 198                                 if (opts->jffs2 && result == 0)
 199                                         printf(" Cleanmarker written at 0x%llx.",
 200                                                erase.addr);
 201                         }
 202                 }
 203         }
 204         if (!opts->quiet)
 205                 printf("\n");
 206
 207         if (nand_block_bad_old) {
 208                 struct nand_chip *priv_nand = meminfo->priv;
 209
 210                 priv_nand->block_bad = nand_block_bad_old;
 211                 priv_nand->scan_bbt(meminfo);
 212         }
 213
 214         return 0;
 215 }
 216
 217 #ifdef CONFIG_CMD_NAND_LOCK_UNLOCK
 218
 219 /******************************************************************************
 220  * Support for locking / unlocking operations of some NAND devices
 221  *****************************************************************************/
 222
 223 #define NAND_CMD_LOCK           0x2a
 224 #define NAND_CMD_LOCK_TIGHT     0x2c
 225 #define NAND_CMD_UNLOCK1        0x23
 226 #define NAND_CMD_UNLOCK2        0x24
 227 #define NAND_CMD_LOCK_STATUS    0x7a
 228
 229 /**
 230  * nand_lock: Set all pages of NAND flash chip to the LOCK or LOCK-TIGHT
 231  *            state
 232  *
 233  * @param mtd           nand mtd instance
 234  * @param tight         bring device in lock tight mode
 235  *
 236  * @return              0 on success, -1 in case of error
 237  *
 238  * The lock / lock-tight command only applies to the whole chip. To get some
 239  * parts of the chip lock and others unlocked use the following sequence:
 240  *
 241  * - Lock all pages of the chip using nand_lock(mtd, 0) (or the lockpre pin)
 242  * - Call nand_unlock() once for each consecutive area to be unlocked
 243  * - If desired: Bring the chip to the lock-tight state using nand_lock(mtd, 1)
 244  *
 245  *   If the device is in lock-tight state software can't change the
 246  *   current active lock/unlock state of all pages. nand_lock() / nand_unlock()
 247  *   calls will fail. It is only posible to leave lock-tight state by
 248  *   an hardware signal (low pulse on _WP pin) or by power down.
 249  */
 250 int nand_lock(struct mtd_info *mtd, int tight)
 251 {
 252         int ret = 0;
 253         int status;
 254         struct nand_chip *chip = mtd->priv;
 255
 256         /* select the NAND device */
 257         chip->select_chip(mtd, 0);
 258
 259         chip->cmdfunc(mtd,
 260                       (tight ? NAND_CMD_LOCK_TIGHT : NAND_CMD_LOCK),
 261                       -1, -1);
 262
 263         /* call wait ready function */
 264         status = chip->waitfunc(mtd, chip);
 265
 266         /* see if device thinks it succeeded */
 267         if (status & 0x01) {
 268                 ret = -1;
 269         }
 270
 271         /* de-select the NAND device */
 272         chip->select_chip(mtd, -1);
 273         return ret;
 274 }
 275
 276 /**
 277  * nand_get_lock_status: - query current lock state from one page of NAND
 278  *                         flash
 279  *
 280  * @param mtd           nand mtd instance
 281  * @param offset        page address to query (muss be page aligned!)
 282  *
 283  * @return              -1 in case of error
 284  *                      >0 lock status:
 285  *                        bitfield with the following combinations:
 286  *                        NAND_LOCK_STATUS_TIGHT: page in tight state
 287  *                        NAND_LOCK_STATUS_LOCK:  page locked
 288  *                        NAND_LOCK_STATUS_UNLOCK: page unlocked
 289  *
 290  */
 291 int nand_get_lock_status(struct mtd_info *mtd, loff_t offset)
 292 {
 293         int ret = 0;
 294         int chipnr;
 295         int page;
 296         struct nand_chip *chip = mtd->priv;
 297
 298         /* select the NAND device */
 299         chipnr = (int)(offset >> chip->chip_shift);
 300         chip->select_chip(mtd, chipnr);
 301
 302
 303         if ((offset & (mtd->writesize - 1)) != 0) {
 304                 printf ("nand_get_lock_status: "
 305                         "Start address must be beginning of "
 306                         "nand page!\n");
 307                 ret = -1;
 308                 goto out;
 309         }
 310
 311         /* check the Lock Status */
 312         page = (int)(offset >> chip->page_shift);
 313         chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, page & chip->pagemask);
 314
 315         ret = chip->read_byte(mtd) & (NAND_LOCK_STATUS_TIGHT
 316                                           | NAND_LOCK_STATUS_LOCK
 317                                           | NAND_LOCK_STATUS_UNLOCK);
 318
 319  out:
 320         /* de-select the NAND device */
 321         chip->select_chip(mtd, -1);
 322         return ret;
 323 }
 324
 325 /**
 326  * nand_unlock: - Unlock area of NAND pages
 327  *                only one consecutive area can be unlocked at one time!
 328  *
 329  * @param mtd           nand mtd instance
 330  * @param start         start byte address
 331  * @param length        number of bytes to unlock (must be a multiple of
 332  *                      page size nand->writesize)
 333  *
 334  * @return              0 on success, -1 in case of error
 335  */
 336 int nand_unlock(struct mtd_info *mtd, ulong start, ulong length)
 337 {
 338         int ret = 0;
 339         int chipnr;
 340         int status;
 341         int page;
 342         struct nand_chip *chip = mtd->priv;
 343         printf ("nand_unlock: start: %08x, length: %d!\n",
 344                 (int)start, (int)length);
 345
 346         /* select the NAND device */
 347         chipnr = (int)(start >> chip->chip_shift);
 348         chip->select_chip(mtd, chipnr);
 349
 350         /* check the WP bit */
 351         chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
 352         if (!(chip->read_byte(mtd) & NAND_STATUS_WP)) {
 353                 printf ("nand_unlock: Device is write protected!\n");
 354                 ret = -1;
 355                 goto out;
 356         }
 357
 358         if ((start & (mtd->erasesize - 1)) != 0) {
 359                 printf ("nand_unlock: Start address must be beginning of "
 360                         "nand block!\n");
 361                 ret = -1;
 362                 goto out;
 363         }
 364
 365         if (length == 0 || (length & (mtd->erasesize - 1)) != 0) {
 366                 printf ("nand_unlock: Length must be a multiple of nand block "
 367                         "size %08x!\n", mtd->erasesize);
 368                 ret = -1;
 369                 goto out;
 370         }
 371
 372         /*
 373          * Set length so that the last address is set to the
 374          * starting address of the last block
 375          */
 376         length -= mtd->erasesize;
 377
 378         /* submit address of first page to unlock */
 379         page = (int)(start >> chip->page_shift);
 380         chip->cmdfunc(mtd, NAND_CMD_UNLOCK1, -1, page & chip->pagemask);
 381
 382         /* submit ADDRESS of LAST page to unlock */
 383         page += (int)(length >> chip->page_shift);
 384         chip->cmdfunc(mtd, NAND_CMD_UNLOCK2, -1, page & chip->pagemask);
 385
 386         /* call wait ready function */
 387         status = chip->waitfunc(mtd, chip);
 388         /* see if device thinks it succeeded */
 389         if (status & 0x01) {
 390                 /* there was an error */
 391                 ret = -1;
 392                 goto out;
 393         }
 394
 395  out:
 396         /* de-select the NAND device */
 397         chip->select_chip(mtd, -1);
 398         return ret;
 399 }
 400 #endif
 401
 402 /**
 403  * check_skip_len
 404  *
 405  * Check if there are any bad blocks, and whether length including bad
 406  * blocks fits into device
 407  *
 408  * @param nand NAND device
 409  * @param offset offset in flash
 410  * @param length image length
 411  * @return 0 if the image fits and there are no bad blocks
 412  *         1 if the image fits, but there are bad blocks
 413  *        -1 if the image does not fit
 414  */
 415 static int check_skip_len(nand_info_t *nand, loff_t offset, size_t length)
 416 {
 417         size_t len_excl_bad = 0;
 418         int ret = 0;
 419
 420         while (len_excl_bad < length) {
 421                 size_t block_len, block_off;
 422                 loff_t block_start;
 423
 424                 if (offset >= nand->size)
 425                         return -1;
 426
 427                 block_start = offset & ~(loff_t)(nand->erasesize - 1);
 428                 block_off = offset & (nand->erasesize - 1);
 429                 block_len = nand->erasesize - block_off;
 430
 431                 if (!nand_block_isbad(nand, block_start))
 432                         len_excl_bad += block_len;
 433                 else
 434                         ret = 1;
 435
 436                 offset += block_len;
 437         }
 438
 439         return ret;
 440 }
 441
 442 #ifdef CONFIG_CMD_NAND_TRIMFFS
 443 static size_t drop_ffs(const nand_info_t *nand, const u_char *buf,
 444                         const size_t *len)
 445 {
 446         size_t i, l = *len;
 447
 448         for (i = l - 1; i >= 0; i--)
 449                 if (buf[i] != 0xFF)
 450                         break;
 451
 452         /* The resulting length must be aligned to the minimum flash I/O size */
 453         l = i + 1;
 454         l = (l + nand->writesize - 1) / nand->writesize;
 455         l *=  nand->writesize;
 456
 457         /*
 458          * since the input length may be unaligned, prevent access past the end
 459          * of the buffer
 460          */
 461         return min(l, *len);
 462 }
 463 #endif
 464
 465 /**
 466  * nand_write_skip_bad:
 467  *
 468  * Write image to NAND flash.
 469  * Blocks that are marked bad are skipped and the is written to the next
 470  * block instead as long as the image is short enough to fit even after
 471  * skipping the bad blocks.
 472  *
 473  * @param nand          NAND device
 474  * @param offset        offset in flash
 475  * @param length        buffer length
 476  * @param buffer        buffer to read from
 477  * @param flags         flags modifying the behaviour of the write to NAND
 478  * @return              0 in case of success
 479  */
 480 int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
 481                         u_char *buffer, int flags)
 482 {
 483         int rval = 0, blocksize;
 484         size_t left_to_write = *length;
 485         u_char *p_buffer = buffer;
 486         int need_skip;
 487
 488 #ifdef CONFIG_CMD_NAND_YAFFS
 489         if (flags & WITH_YAFFS_OOB) {
 490                 if (flags & ~WITH_YAFFS_OOB)
 491                         return -EINVAL;
 492
 493                 int pages;
 494                 pages = nand->erasesize / nand->writesize;
 495                 blocksize = (pages * nand->oobsize) + nand->erasesize;
 496                 if (*length % (nand->writesize + nand->oobsize)) {
 497                         printf ("Attempt to write incomplete page"
 498                                 " in yaffs mode\n");
 499                         return -EINVAL;
 500                 }
 501         } else
 502 #endif
 503         {
 504                 blocksize = nand->erasesize;
 505         }
 506
 507         /*
 508          * nand_write() handles unaligned, partial page writes.
 509          *
 510          * We allow length to be unaligned, for convenience in
 511          * using the $filesize variable.
 512          *
 513          * However, starting at an unaligned offset makes the
 514          * semantics of bad block skipping ambiguous (really,
 515          * you should only start a block skipping access at a
 516          * partition boundary).  So don't try to handle that.
 517          */
 518         if ((offset & (nand->writesize - 1)) != 0) {
 519                 printf ("Attempt to write non page aligned data\n");
 520                 *length = 0;
 521                 return -EINVAL;
 522         }
 523
 524         need_skip = check_skip_len(nand, offset, *length);
 525         if (need_skip < 0) {
 526                 printf ("Attempt to write outside the flash area\n");
 527                 *length = 0;
 528                 return -EINVAL;
 529         }
 530
 531         if (!need_skip && !(flags & WITH_DROP_FFS)) {
 532                 rval = nand_write (nand, offset, length, buffer);
 533                 if (rval == 0)
 534                         return 0;
 535
 536                 *length = 0;
 537                 printf ("NAND write to offset %llx failed %d\n",
 538                         offset, rval);
 539                 return rval;
 540         }
 541
 542         while (left_to_write > 0) {
 543                 size_t block_offset = offset & (nand->erasesize - 1);
 544                 size_t write_size, truncated_write_size;
 545
 546                 WATCHDOG_RESET ();
 547
 548                 if (nand_block_isbad (nand, offset & ~(nand->erasesize - 1))) {
 549                         printf ("Skip bad block 0x%08llx\n",
 550                                 offset & ~(nand->erasesize - 1));
 551                         offset += nand->erasesize - block_offset;
 552                         continue;
 553                 }
 554
 555                 if (left_to_write < (blocksize - block_offset))
 556                         write_size = left_to_write;
 557                 else
 558                         write_size = blocksize - block_offset;
 559
 560 #ifdef CONFIG_CMD_NAND_YAFFS
 561                 if (flags & WITH_YAFFS_OOB) {
 562                         int page, pages;
 563                         size_t pagesize = nand->writesize;
 564                         size_t pagesize_oob = pagesize + nand->oobsize;
 565                         struct mtd_oob_ops ops;
 566
 567                         ops.len = pagesize;
 568                         ops.ooblen = nand->oobsize;
 569                         ops.mode = MTD_OOB_AUTO;
 570                         ops.ooboffs = 0;
 571
 572                         pages = write_size / pagesize_oob;
 573                         for (page = 0; page < pages; page++) {
 574                                 WATCHDOG_RESET();
 575
 576                                 ops.datbuf = p_buffer;
 577                                 ops.oobbuf = ops.datbuf + pagesize;
 578
 579                                 rval = nand->write_oob(nand, offset, &ops);
 580                                 if (!rval)
 581                                         break;
 582
 583                                 offset += pagesize;
 584                                 p_buffer += pagesize_oob;
 585                         }
 586                 }
 587                 else
 588 #endif
 589                 {
 590                         truncated_write_size = write_size;
 591 #ifdef CONFIG_CMD_NAND_TRIMFFS
 592                         if (flags & WITH_DROP_FFS)
 593                                 truncated_write_size = drop_ffs(nand, p_buffer,
 594                                                 &write_size);
 595 #endif
 596
 597                         rval = nand_write(nand, offset, &truncated_write_size,
 598                                         p_buffer);
 599                         offset += write_size;
 600                         p_buffer += write_size;
 601                 }
 602
 603                 if (rval != 0) {
 604                         printf ("NAND write to offset %llx failed %d\n",
 605                                 offset, rval);
 606                         *length -= left_to_write;
 607                         return rval;
 608                 }
 609
 610                 left_to_write -= write_size;
 611         }
 612
 613         return 0;
 614 }
 615
 616 /**
 617  * nand_read_skip_bad:
 618  *
 619  * Read image from NAND flash.
 620  * Blocks that are marked bad are skipped and the next block is readen
 621  * instead as long as the image is short enough to fit even after skipping the
 622  * bad blocks.
 623  *
 624  * @param nand NAND device
 625  * @param offset offset in flash
 626  * @param length buffer length, on return holds remaining bytes to read
 627  * @param buffer buffer to write to
 628  * @return 0 in case of success
 629  */
 630 int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
 631                        u_char *buffer)
 632 {
 633         int rval;
 634         size_t left_to_read = *length;
 635         u_char *p_buffer = buffer;
 636         int need_skip;
 637
 638         if ((offset & (nand->writesize - 1)) != 0) {
 639                 printf ("Attempt to read non page aligned data\n");
 640                 *length = 0;
 641                 return -EINVAL;
 642         }
 643
 644         need_skip = check_skip_len(nand, offset, *length);
 645         if (need_skip < 0) {
 646                 printf ("Attempt to read outside the flash area\n");
 647                 *length = 0;
 648                 return -EINVAL;
 649         }
 650
 651         if (!need_skip) {
 652                 rval = nand_read (nand, offset, length, buffer);
 653                 if (!rval || rval == -EUCLEAN)
 654                         return 0;
 655
 656                 *length = 0;
 657                 printf ("NAND read from offset %llx failed %d\n",
 658                         offset, rval);
 659                 return rval;
 660         }
 661
 662         while (left_to_read > 0) {
 663                 size_t block_offset = offset & (nand->erasesize - 1);
 664                 size_t read_length;
 665
 666                 WATCHDOG_RESET ();
 667
 668                 if (nand_block_isbad (nand, offset & ~(nand->erasesize - 1))) {
 669                         printf ("Skipping bad block 0x%08llx\n",
 670                                 offset & ~(nand->erasesize - 1));
 671                         offset += nand->erasesize - block_offset;
 672                         continue;
 673                 }
 674
 675                 if (left_to_read < (nand->erasesize - block_offset))
 676                         read_length = left_to_read;
 677                 else
 678                         read_length = nand->erasesize - block_offset;
 679
 680                 rval = nand_read (nand, offset, &read_length, p_buffer);
 681                 if (rval && rval != -EUCLEAN) {
 682                         printf ("NAND read from offset %llx failed %d\n",
 683                                 offset, rval);
 684                         *length -= left_to_read;
 685                         return rval;
 686                 }
 687
 688                 left_to_read -= read_length;
 689                 offset       += read_length;
 690                 p_buffer     += read_length;
 691         }
 692
 693         return 0;
 694 }