target/linux/generic-2.6/files-2.6.25/fs/yaffs2/yaffs_mtdif1.c

   1 /*
   2  * YAFFS: Yet another FFS. A NAND-flash specific file system.
   3  * yaffs_mtdif1.c  NAND mtd interface functions for small-page NAND.
   4  *
   5  * Copyright (C) 2002 Aleph One Ltd.
   6  *   for Toby Churchill Ltd and Brightstar Engineering
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 /*
  14  * This module provides the interface between yaffs_nand.c and the
  15  * MTD API.  This version is used when the MTD interface supports the
  16  * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
  17  * and we have small-page NAND device.
  18  *
  19  * These functions are invoked via function pointers in yaffs_nand.c.
  20  * This replaces functionality provided by functions in yaffs_mtdif.c
  21  * and the yaffs_TagsCompatability functions in yaffs_tagscompat.c that are
  22  * called in yaffs_mtdif.c when the function pointers are NULL.
  23  * We assume the MTD layer is performing ECC (useNANDECC is true).
  24  */
  25
  26 #include "yportenv.h"
  27 #include "yaffs_guts.h"
  28 #include "yaffs_packedtags1.h"
  29 #include "yaffs_tagscompat.h"   // for yaffs_CalcTagsECC
  30
  31 #include "linux/kernel.h"
  32 #include "linux/version.h"
  33 #include "linux/types.h"
  34 #include "linux/mtd/mtd.h"
  35
  36 /* Don't compile this module if we don't have MTD's mtd_oob_ops interface */
  37 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,17))
  38
  39 const char *yaffs_mtdif1_c_version = "$Id: yaffs_mtdif1.c,v 1.3 2007/05/15 20:16:11 ian Exp $";
  40
  41 #ifndef CONFIG_YAFFS_9BYTE_TAGS
  42 # define YTAG1_SIZE 8
  43 #else
  44 # define YTAG1_SIZE 9
  45 #endif
  46
  47 #if 0
  48 /* Use the following nand_ecclayout with MTD when using
  49  * CONFIG_YAFFS_9BYTE_TAGS and the older on-NAND tags layout.
  50  * If you have existing Yaffs images and the byte order differs from this,
  51  * adjust 'oobfree' to match your existing Yaffs data.
  52  *
  53  * This nand_ecclayout scatters/gathers to/from the old-yaffs layout with the
  54  * pageStatus byte (at NAND spare offset 4) scattered/gathered from/to
  55  * the 9th byte.
  56  *
  57  * Old-style on-NAND format: T0,T1,T2,T3,P,B,T4,T5,E0,E1,E2,T6,T7,E3,E4,E5
  58  * We have/need PackedTags1 plus pageStatus: T0,T1,T2,T3,T4,T5,T6,T7,P
  59  * where Tn are the tag bytes, En are MTD's ECC bytes, P is the pageStatus
  60  * byte and B is the small-page bad-block indicator byte.
  61  */
  62 static struct nand_ecclayout nand_oob_16 = {
  63         .eccbytes = 6,
  64         .eccpos = { 8, 9, 10, 13, 14, 15 },
  65         .oobavail = 9,
  66         .oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
  67 };
  68 #endif
  69
  70 /* Write a chunk (page) of data to NAND.
  71  *
  72  * Caller always provides ExtendedTags data which are converted to a more
  73  * compact (packed) form for storage in NAND.  A mini-ECC runs over the
  74  * contents of the tags meta-data; used to valid the tags when read.
  75  *
  76  *  - Pack ExtendedTags to PackedTags1 form
  77  *  - Compute mini-ECC for PackedTags1
  78  *  - Write data and packed tags to NAND.
  79  *
  80  * Note: Due to the use of the PackedTags1 meta-data which does not include
  81  * a full sequence number (as found in the larger PackedTags2 form) it is
  82  * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
  83  * discarded and dirty.  This is not ideal: newer NAND parts are supposed
  84  * to be written just once.  When Yaffs performs this operation, this
  85  * function is called with a NULL data pointer -- calling MTD write_oob
  86  * without data is valid usage (2.6.17).
  87  *
  88  * Any underlying MTD error results in YAFFS_FAIL.
  89  * Returns YAFFS_OK or YAFFS_FAIL.
  90  */
  91 int nandmtd1_WriteChunkWithTagsToNAND(yaffs_Device *dev,
  92         int chunkInNAND, const __u8 * data, const yaffs_ExtendedTags * etags)
  93 {
  94         struct mtd_info * mtd = dev->genericDevice;
  95         int chunkBytes = dev->nDataBytesPerChunk;
  96         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
  97         struct mtd_oob_ops ops;
  98         yaffs_PackedTags1 pt1;
  99         int retval;
 100
 101         /* we assume that PackedTags1 and yaffs_Tags are compatible */
 102         compile_time_assertion(sizeof(yaffs_PackedTags1) == 12);
 103         compile_time_assertion(sizeof(yaffs_Tags) == 8);
 104
 105         dev->nPageWrites++;
 106
 107         yaffs_PackTags1(&pt1, etags);
 108         yaffs_CalcTagsECC((yaffs_Tags *)&pt1);
 109
 110         /* When deleting a chunk, the upper layer provides only skeletal
 111          * etags, one with chunkDeleted set.  However, we need to update the
 112          * tags, not erase them completely.  So we use the NAND write property
 113          * that only zeroed-bits stick and set tag bytes to all-ones and
 114          * zero just the (not) deleted bit.
 115          */
 116 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 117         if (etags->chunkDeleted) {
 118                 memset(&pt1, 0xff, 8);
 119                 /* clear delete status bit to indicate deleted */
 120                 pt1.deleted = 0;
 121         }
 122 #else
 123         ((__u8 *)&pt1)[8] = 0xff;
 124         if (etags->chunkDeleted) {
 125                 memset(&pt1, 0xff, 8);
 126                 /* zero pageStatus byte to indicate deleted */
 127                 ((__u8 *)&pt1)[8] = 0;
 128         }
 129 #endif
 130
 131         memset(&ops, 0, sizeof(ops));
 132         ops.mode = MTD_OOB_AUTO;
 133         ops.len = (data) ? chunkBytes : 0;
 134         ops.ooblen = YTAG1_SIZE;
 135         ops.datbuf = (__u8 *)data;
 136         ops.oobbuf = (__u8 *)&pt1;
 137
 138         retval = mtd->write_oob(mtd, addr, &ops);
 139         if (retval) {
 140                 yaffs_trace(YAFFS_TRACE_MTD,
 141                         "write_oob failed, chunk %d, mtd error %d\n",
 142                         chunkInNAND, retval);
 143         }
 144         return retval ? YAFFS_FAIL : YAFFS_OK;
 145 }
 146
 147 /* Return with empty ExtendedTags but add eccResult.
 148  */
 149 static int rettags(yaffs_ExtendedTags * etags, int eccResult, int retval)
 150 {
 151         if (etags) {
 152                 memset(etags, 0, sizeof(*etags));
 153                 etags->eccResult = eccResult;
 154         }
 155         return retval;
 156 }
 157
 158 /* Read a chunk (page) from NAND.
 159  *
 160  * Caller expects ExtendedTags data to be usable even on error; that is,
 161  * all members except eccResult and blockBad are zeroed.
 162  *
 163  *  - Check ECC results for data (if applicable)
 164  *  - Check for blank/erased block (return empty ExtendedTags if blank)
 165  *  - Check the PackedTags1 mini-ECC (correct if necessary/possible)
 166  *  - Convert PackedTags1 to ExtendedTags
 167  *  - Update eccResult and blockBad members to refect state.
 168  *
 169  * Returns YAFFS_OK or YAFFS_FAIL.
 170  */
 171 int nandmtd1_ReadChunkWithTagsFromNAND(yaffs_Device *dev,
 172         int chunkInNAND, __u8 * data, yaffs_ExtendedTags * etags)
 173 {
 174         struct mtd_info * mtd = dev->genericDevice;
 175         int chunkBytes = dev->nDataBytesPerChunk;
 176         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
 177         int eccres = YAFFS_ECC_RESULT_NO_ERROR;
 178         struct mtd_oob_ops ops;
 179         yaffs_PackedTags1 pt1;
 180         int retval;
 181         int deleted;
 182
 183         dev->nPageReads++;
 184
 185         memset(&ops, 0, sizeof(ops));
 186         ops.mode = MTD_OOB_AUTO;
 187         ops.len = (data) ? chunkBytes : 0;
 188         ops.ooblen = YTAG1_SIZE;
 189         ops.datbuf = data;
 190         ops.oobbuf = (__u8 *)&pt1;
 191
 192 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20))
 193         /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
 194          * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
 195          */
 196         ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
 197 #endif
 198         /* Read page and oob using MTD.
 199          * Check status and determine ECC result.
 200          */
 201         retval = mtd->read_oob(mtd, addr, &ops);
 202         if (retval) {
 203                 yaffs_trace(YAFFS_TRACE_MTD,
 204                         "read_oob failed, chunk %d, mtd error %d\n",
 205                         chunkInNAND, retval);
 206         }
 207
 208         switch (retval) {
 209         case 0:
 210                 /* no error */
 211                 break;
 212
 213         case -EUCLEAN:
 214                 /* MTD's ECC fixed the data */
 215                 eccres = YAFFS_ECC_RESULT_FIXED;
 216                 dev->eccFixed++;
 217                 break;
 218
 219         case -EBADMSG:
 220                 /* MTD's ECC could not fix the data */
 221                 dev->eccUnfixed++;
 222                 /* fall into... */
 223         default:
 224                 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
 225                 etags->blockBad = (mtd->block_isbad)(mtd, addr);
 226                 return YAFFS_FAIL;
 227         }
 228
 229         /* Check for a blank/erased chunk.
 230          */
 231         if (yaffs_CheckFF((__u8 *)&pt1, 8)) {
 232                 /* when blank, upper layers want eccResult to be <= NO_ERROR */
 233                 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
 234         }
 235
 236 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 237         /* Read deleted status (bit) then return it to it's non-deleted
 238          * state before performing tags mini-ECC check. pt1.deleted is
 239          * inverted.
 240          */
 241         deleted = !pt1.deleted;
 242         pt1.deleted = 1;
 243 #else
 244         deleted = (yaffs_CountBits(((__u8 *)&pt1)[8]) < 7);
 245 #endif
 246
 247         /* Check the packed tags mini-ECC and correct if necessary/possible.
 248          */
 249         retval = yaffs_CheckECCOnTags((yaffs_Tags *)&pt1);
 250         switch (retval) {
 251         case 0:
 252                 /* no tags error, use MTD result */
 253                 break;
 254         case 1:
 255                 /* recovered tags-ECC error */
 256                 dev->tagsEccFixed++;
 257                 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
 258                         eccres = YAFFS_ECC_RESULT_FIXED;
 259                 break;
 260         default:
 261                 /* unrecovered tags-ECC error */
 262                 dev->tagsEccUnfixed++;
 263                 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
 264         }
 265
 266         /* Unpack the tags to extended form and set ECC result.
 267          * [set shouldBeFF just to keep yaffs_UnpackTags1 happy]
 268          */
 269         pt1.shouldBeFF = 0xFFFFFFFF;
 270         yaffs_UnpackTags1(etags, &pt1);
 271         etags->eccResult = eccres;
 272
 273         /* Set deleted state */
 274         etags->chunkDeleted = deleted;
 275         return YAFFS_OK;
 276 }
 277
 278 /* Mark a block bad.
 279  *
 280  * This is a persistant state.
 281  * Use of this function should be rare.
 282  *
 283  * Returns YAFFS_OK or YAFFS_FAIL.
 284  */
 285 int nandmtd1_MarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockNo)
 286 {
 287         struct mtd_info * mtd = dev->genericDevice;
 288         int blocksize = dev->nChunksPerBlock * dev->nDataBytesPerChunk;
 289         int retval;
 290
 291         yaffs_trace(YAFFS_TRACE_BAD_BLOCKS, "marking block %d bad", blockNo);
 292
 293         retval = mtd->block_markbad(mtd, (loff_t)blocksize * blockNo);
 294         return (retval) ? YAFFS_FAIL : YAFFS_OK;
 295 }
 296
 297 /* Check any MTD prerequists.
 298  *
 299  * Returns YAFFS_OK or YAFFS_FAIL.
 300  */
 301 static int nandmtd1_TestPrerequists(struct mtd_info * mtd)
 302 {
 303         /* 2.6.18 has mtd->ecclayout->oobavail */
 304         /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
 305         int oobavail = mtd->ecclayout->oobavail;
 306
 307         if (oobavail < YTAG1_SIZE) {
 308                 yaffs_trace(YAFFS_TRACE_ERROR,
 309                         "mtd device has only %d bytes for tags, need %d\n",
 310                         oobavail, YTAG1_SIZE);
 311                 return YAFFS_FAIL;
 312         }
 313         return YAFFS_OK;
 314 }
 315
 316 /* Query for the current state of a specific block.
 317  *
 318  * Examine the tags of the first chunk of the block and return the state:
 319  *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
 320  *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
 321  *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
 322  *
 323  * Always returns YAFFS_OK.
 324  */
 325 int nandmtd1_QueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo,
 326         yaffs_BlockState * pState, int *pSequenceNumber)
 327 {
 328         struct mtd_info * mtd = dev->genericDevice;
 329         int chunkNo = blockNo * dev->nChunksPerBlock;
 330         yaffs_ExtendedTags etags;
 331         int state = YAFFS_BLOCK_STATE_DEAD;
 332         int seqnum = 0;
 333         int retval;
 334
 335         /* We don't yet have a good place to test for MTD config prerequists.
 336          * Do it here as we are called during the initial scan.
 337          */
 338         if (nandmtd1_TestPrerequists(mtd) != YAFFS_OK) {
 339                 return YAFFS_FAIL;
 340         }
 341
 342         retval = nandmtd1_ReadChunkWithTagsFromNAND(dev, chunkNo, NULL, &etags);
 343         if (etags.blockBad) {
 344                 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
 345                         "block %d is marked bad", blockNo);
 346                 state = YAFFS_BLOCK_STATE_DEAD;
 347         }
 348         else if (etags.chunkUsed) {
 349                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 350                 seqnum = etags.sequenceNumber;
 351         }
 352         else {
 353                 state = YAFFS_BLOCK_STATE_EMPTY;
 354         }
 355
 356         *pState = state;
 357         *pSequenceNumber = seqnum;
 358
 359         /* query always succeeds */
 360         return YAFFS_OK;
 361 }
 362
 363 #endif /*KERNEL_VERSION*/