target/linux/generic-2.6/files/fs/yaffs2/yaffs_mtdif1-compat.c

   1 From ian@brightstareng.com Fri May 18 15:06:49 2007
   2 From ian@brightstareng.com Fri May 18 15:08:21 2007
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  17 From: Ian McDonnell <ian@brightstareng.com>
  18 To: David Goodenough <david.goodenough@linkchoose.co.uk>
  19 Subject: Re: something tested this time -- yaffs_mtdif1-compat.c
  20 Date: Fri, 18 May 2007 10:06:49 -0400
  21 User-Agent: KMail/1.9.1
  22 References: <200705142207.06909.ian@brightstareng.com> <200705171131.53536.ian@brightstareng.com> <200705181334.32166.david.goodenough@linkchoose.co.uk>
  23 In-Reply-To: <200705181334.32166.david.goodenough@linkchoose.co.uk>
  24 Cc: Andrea Conti <alyf@alyf.net>,
  25  Charles Manning <manningc2@actrix.gen.nz>
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  42
  43 David, Andrea,
  44
  45 On Friday 18 May 2007 08:34, you wrote:
  46 > Yea team.  With this fix in place (I put it in the wrong place
  47 > at first) I can now mount and ls the Yaffs partition without
  48 > an error messages!
  49
  50 Good news!
  51
  52 Attached is a newer yaffs_mtdif1.c with a bandaid to help the
  53 2.6.18 and 2.6.19 versions of MTD not trip on the oob read.
  54 See the LINUX_VERSION_CODE conditional in
  55 nandmtd1_ReadChunkWithTagsFromNAND.
  56
  57 -imcd
  58
  59 --Boundary-00=_5LbTGmt62YoutxM
  60 Content-Type: text/x-csrc;
  61   charset="iso-8859-15";
  62   name="yaffs_mtdif1.c"
  63 Content-Transfer-Encoding: 7bit
  64 Content-Disposition: attachment;
  65         filename="yaffs_mtdif1.c"
  66
  67 /*
  68  * YAFFS: Yet another FFS. A NAND-flash specific file system.
  69  * yaffs_mtdif1.c  NAND mtd interface functions for small-page NAND.
  70  *
  71  * Copyright (C) 2002 Aleph One Ltd.
  72  *   for Toby Churchill Ltd and Brightstar Engineering
  73  *
  74  * This program is free software; you can redistribute it and/or modify
  75  * it under the terms of the GNU General Public License version 2 as
  76  * published by the Free Software Foundation.
  77  */
  78
  79 /*
  80  * This module provides the interface between yaffs_nand.c and the
  81  * MTD API.  This version is used when the MTD interface supports the
  82  * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
  83  * and we have small-page NAND device.
  84  *
  85  * These functions are invoked via function pointers in yaffs_nand.c.
  86  * This replaces functionality provided by functions in yaffs_mtdif.c
  87  * and the yaffs_TagsCompatability functions in yaffs_tagscompat.c that are
  88  * called in yaffs_mtdif.c when the function pointers are NULL.
  89  * We assume the MTD layer is performing ECC (useNANDECC is true).
  90  */
  91
  92 #include "yportenv.h"
  93 #include "yaffs_guts.h"
  94 #include "yaffs_packedtags1.h"
  95 #include "yaffs_tagscompat.h"   // for yaffs_CalcTagsECC
  96
  97 #include "linux/kernel.h"
  98 #include "linux/version.h"
  99 #include "linux/types.h"
 100 #include "linux/mtd/mtd.h"
 101
 102 /* Don't compile this module if we don't have MTD's mtd_oob_ops interface */
 103 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,17))
 104
 105
 106 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 107 # define YTAG1_SIZE 8
 108 #else
 109 # define YTAG1_SIZE 9
 110 #endif
 111
 112 #if 0
 113 /* Use the following nand_ecclayout with MTD when using
 114  * CONFIG_YAFFS_9BYTE_TAGS and the older on-NAND tags layout.
 115  * If you have existing Yaffs images and the byte order differs from this,
 116  * adjust 'oobfree' to match your existing Yaffs data.
 117  *
 118  * This nand_ecclayout scatters/gathers to/from the old-yaffs layout with the
 119  * pageStatus byte (at NAND spare offset 4) scattered/gathered from/to
 120  * the 9th byte.
 121  *
 122  * Old-style on-NAND format: T0,T1,T2,T3,P,B,T4,T5,E0,E1,E2,T6,T7,E3,E4,E5
 123  * We have/need PackedTags1 plus pageStatus: T0,T1,T2,T3,T4,T5,T6,T7,P
 124  * where Tn are the tag bytes, En are MTD's ECC bytes, P is the pageStatus
 125  * byte and B is the small-page bad-block indicator byte.
 126  */
 127 static struct nand_ecclayout nand_oob_16 = {
 128         .eccbytes = 6,
 129         .eccpos = { 8, 9, 10, 13, 14, 15 },
 130         .oobavail = 9,
 131         .oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
 132 };
 133 #endif
 134
 135 /* Write a chunk (page) of data to NAND.
 136  *
 137  * Caller always provides ExtendedTags data which are converted to a more
 138  * compact (packed) form for storage in NAND.  A mini-ECC runs over the
 139  * contents of the tags meta-data; used to valid the tags when read.
 140  *
 141  *  - Pack ExtendedTags to PackedTags1 form
 142  *  - Compute mini-ECC for PackedTags1
 143  *  - Write data and packed tags to NAND.
 144  *
 145  * Note: Due to the use of the PackedTags1 meta-data which does not include
 146  * a full sequence number (as found in the larger PackedTags2 form) it is
 147  * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
 148  * discarded and dirty.  This is not ideal: newer NAND parts are supposed
 149  * to be written just once.  When Yaffs performs this operation, this
 150  * function is called with a NULL data pointer -- calling MTD write_oob
 151  * without data is valid usage (2.6.17).
 152  *
 153  * Any underlying MTD error results in YAFFS_FAIL.
 154  * Returns YAFFS_OK or YAFFS_FAIL.
 155  */
 156 int nandmtd1_WriteChunkWithTagsToNAND(yaffs_Device *dev,
 157         int chunkInNAND, const __u8 * data, const yaffs_ExtendedTags * etags)
 158 {
 159         struct mtd_info * mtd = dev->genericDevice;
 160         int chunkBytes = dev->nDataBytesPerChunk;
 161         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
 162         struct mtd_oob_ops ops;
 163         yaffs_PackedTags1 pt1;
 164         int retval;
 165
 166         /* we assume that PackedTags1 and yaffs_Tags are compatible */
 167         compile_time_assertion(sizeof(yaffs_PackedTags1) == 12);
 168         compile_time_assertion(sizeof(yaffs_Tags) == 8);
 169
 170         yaffs_PackTags1(&pt1, etags);
 171         yaffs_CalcTagsECC((yaffs_Tags *)&pt1);
 172
 173         /* When deleting a chunk, the upper layer provides only skeletal
 174          * etags, one with chunkDeleted set.  However, we need to update the
 175          * tags, not erase them completely.  So we use the NAND write property
 176          * that only zeroed-bits stick and set tag bytes to all-ones and
 177          * zero just the (not) deleted bit.
 178          */
 179 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 180         if (etags->chunkDeleted) {
 181                 memset(&pt1, 0xff, 8);
 182                 /* clear delete status bit to indicate deleted */
 183                 pt1.deleted = 0;
 184         }
 185 #else
 186         ((__u8 *)&pt1)[8] = 0xff;
 187         if (etags->chunkDeleted) {
 188                 memset(&pt1, 0xff, 8);
 189                 /* zero pageStatus byte to indicate deleted */
 190                 ((__u8 *)&pt1)[8] = 0;
 191         }
 192 #endif
 193
 194         memset(&ops, 0, sizeof(ops));
 195         ops.mode = MTD_OOB_AUTO;
 196         ops.len = (data) ? chunkBytes : 0;
 197         ops.ooblen = YTAG1_SIZE;
 198         ops.datbuf = (__u8 *)data;
 199         ops.oobbuf = (__u8 *)&pt1;
 200
 201         retval = mtd->write_oob(mtd, addr, &ops);
 202         if (retval) {
 203                 yaffs_trace(YAFFS_TRACE_MTD,
 204                         "write_oob failed, chunk %d, mtd error %d\n",
 205                         chunkInNAND, retval);
 206         }
 207         return retval ? YAFFS_FAIL : YAFFS_OK;
 208 }
 209
 210 /* Return with empty ExtendedTags but add eccResult.
 211  */
 212 static int rettags(yaffs_ExtendedTags * etags, int eccResult, int retval)
 213 {
 214         if (etags) {
 215                 memset(etags, 0, sizeof(*etags));
 216                 etags->eccResult = eccResult;
 217         }
 218         return retval;
 219 }
 220
 221 /* Read a chunk (page) from NAND.
 222  *
 223  * Caller expects ExtendedTags data to be usable even on error; that is,
 224  * all members except eccResult and blockBad are zeroed.
 225  *
 226  *  - Check ECC results for data (if applicable)
 227  *  - Check for blank/erased block (return empty ExtendedTags if blank)
 228  *  - Check the PackedTags1 mini-ECC (correct if necessary/possible)
 229  *  - Convert PackedTags1 to ExtendedTags
 230  *  - Update eccResult and blockBad members to refect state.
 231  *
 232  * Returns YAFFS_OK or YAFFS_FAIL.
 233  */
 234 int nandmtd1_ReadChunkWithTagsFromNAND(yaffs_Device *dev,
 235         int chunkInNAND, __u8 * data, yaffs_ExtendedTags * etags)
 236 {
 237         struct mtd_info * mtd = dev->genericDevice;
 238         int chunkBytes = dev->nDataBytesPerChunk;
 239         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
 240         int eccres = YAFFS_ECC_RESULT_NO_ERROR;
 241         struct mtd_oob_ops ops;
 242         yaffs_PackedTags1 pt1;
 243         int retval;
 244         int deleted;
 245
 246         memset(&ops, 0, sizeof(ops));
 247         ops.mode = MTD_OOB_AUTO;
 248         ops.len = (data) ? chunkBytes : 0;
 249         ops.ooblen = YTAG1_SIZE;
 250         ops.datbuf = data;
 251         ops.oobbuf = (__u8 *)&pt1;
 252
 253 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20))
 254         /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
 255          * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
 256          */
 257         ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
 258 #endif
 259         /* Read page and oob using MTD.
 260          * Check status and determine ECC result.
 261          */
 262         retval = mtd->read_oob(mtd, addr, &ops);
 263         if (retval) {
 264                 yaffs_trace(YAFFS_TRACE_MTD,
 265                         "read_oob failed, chunk %d, mtd error %d\n",
 266                         chunkInNAND, retval);
 267         }
 268
 269         switch (retval) {
 270         case 0:
 271                 /* no error */
 272                 break;
 273
 274         case -EUCLEAN:
 275                 /* MTD's ECC fixed the data */
 276                 eccres = YAFFS_ECC_RESULT_FIXED;
 277                 dev->eccFixed++;
 278                 break;
 279
 280         case -EBADMSG:
 281                 /* MTD's ECC could not fix the data */
 282                 dev->eccUnfixed++;
 283                 /* fall into... */
 284         default:
 285                 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
 286                 etags->blockBad = (mtd->block_isbad)(mtd, addr);
 287                 return YAFFS_FAIL;
 288         }
 289
 290         /* Check for a blank/erased chunk.
 291          */
 292         if (yaffs_CheckFF((__u8 *)&pt1, 8)) {
 293                 /* when blank, upper layers want eccResult to be <= NO_ERROR */
 294                 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
 295         }
 296
 297 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 298         /* Read deleted status (bit) then return it to it's non-deleted
 299          * state before performing tags mini-ECC check. pt1.deleted is
 300          * inverted.
 301          */
 302         deleted = !pt1.deleted;
 303         pt1.deleted = 1;
 304 #else
 305         (void) deleted; /* not used */
 306 #endif
 307
 308         /* Check the packed tags mini-ECC and correct if necessary/possible.
 309          */
 310         retval = yaffs_CheckECCOnTags((yaffs_Tags *)&pt1);
 311         switch (retval) {
 312         case 0:
 313                 /* no tags error, use MTD result */
 314                 break;
 315         case 1:
 316                 /* recovered tags-ECC error */
 317                 dev->tagsEccFixed++;
 318                 eccres = YAFFS_ECC_RESULT_FIXED;
 319                 break;
 320         default:
 321                 /* unrecovered tags-ECC error */
 322                 dev->tagsEccUnfixed++;
 323                 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
 324         }
 325
 326         /* Unpack the tags to extended form and set ECC result.
 327          * [set shouldBeFF just to keep yaffs_UnpackTags1 happy]
 328          */
 329         pt1.shouldBeFF = 0xFFFFFFFF;
 330         yaffs_UnpackTags1(etags, &pt1);
 331         etags->eccResult = eccres;
 332
 333         /* Set deleted state.
 334          */
 335 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 336         etags->chunkDeleted = deleted;
 337 #else
 338         etags->chunkDeleted = (yaffs_CountBits(((__u8 *)&pt1)[8]) < 7);
 339 #endif
 340         return YAFFS_OK;
 341 }
 342
 343 /* Mark a block bad.
 344  *
 345  * This is a persistant state.
 346  * Use of this function should be rare.
 347  *
 348  * Returns YAFFS_OK or YAFFS_FAIL.
 349  */
 350 int nandmtd1_MarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockNo)
 351 {
 352         struct mtd_info * mtd = dev->genericDevice;
 353         int blocksize = dev->nChunksPerBlock * dev->nDataBytesPerChunk;
 354         int retval;
 355
 356         yaffs_trace(YAFFS_TRACE_BAD_BLOCKS, "marking block %d bad", blockNo);
 357
 358         retval = mtd->block_markbad(mtd, (loff_t)blocksize * blockNo);
 359         return (retval) ? YAFFS_FAIL : YAFFS_OK;
 360 }
 361
 362 /* Check any MTD prerequists.
 363  *
 364  * Returns YAFFS_OK or YAFFS_FAIL.
 365  */
 366 static int nandmtd1_TestPrerequists(struct mtd_info * mtd)
 367 {
 368         /* 2.6.18 has mtd->ecclayout->oobavail */
 369         /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
 370         int oobavail = mtd->ecclayout->oobavail;
 371
 372         if (oobavail < YTAG1_SIZE) {
 373                 yaffs_trace(YAFFS_TRACE_ERROR,
 374                         "mtd device has only %d bytes for tags, need %d",
 375                         oobavail, YTAG1_SIZE);
 376                 return YAFFS_FAIL;
 377         }
 378         return YAFFS_OK;
 379 }
 380
 381 /* Query for the current state of a specific block.
 382  *
 383  * Examine the tags of the first chunk of the block and return the state:
 384  *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
 385  *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
 386  *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
 387  *
 388  * Always returns YAFFS_OK.
 389  */
 390 int nandmtd1_QueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo,
 391         yaffs_BlockState * pState, int *pSequenceNumber)
 392 {
 393         struct mtd_info * mtd = dev->genericDevice;
 394         int chunkNo = blockNo * dev->nChunksPerBlock;
 395         yaffs_ExtendedTags etags;
 396         int state = YAFFS_BLOCK_STATE_DEAD;
 397         int seqnum = 0;
 398         int retval;
 399
 400         /* We don't yet have a good place to test for MTD config prerequists.
 401          * Do it here as we are called during the initial scan.
 402          */
 403         if (nandmtd1_TestPrerequists(mtd) != YAFFS_OK) {
 404                 return YAFFS_FAIL;
 405         }
 406
 407         retval = nandmtd1_ReadChunkWithTagsFromNAND(dev, chunkNo, NULL, &etags);
 408         if (etags.blockBad) {
 409                 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
 410                         "block %d is marked bad", blockNo);
 411                 state = YAFFS_BLOCK_STATE_DEAD;
 412         }
 413         else if (etags.chunkUsed) {
 414                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 415                 seqnum = etags.sequenceNumber;
 416         }
 417         else {
 418                 state = YAFFS_BLOCK_STATE_EMPTY;
 419         }
 420
 421         *pState = state;
 422         *pSequenceNumber = seqnum;
 423
 424         /* query always succeeds */
 425         return YAFFS_OK;
 426 }
 427
 428 #endif /*KERNEL_VERSION*/
 429
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