target/linux/generic-2.6/files/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
  40 #ifndef CONFIG_YAFFS_9BYTE_TAGS
  41 # define YTAG1_SIZE 8
  42 #else
  43 # define YTAG1_SIZE 9
  44 #endif
  45
  46 #if 0
  47 /* Use the following nand_ecclayout with MTD when using
  48  * CONFIG_YAFFS_9BYTE_TAGS and the older on-NAND tags layout.
  49  * If you have existing Yaffs images and the byte order differs from this,
  50  * adjust 'oobfree' to match your existing Yaffs data.
  51  *
  52  * This nand_ecclayout scatters/gathers to/from the old-yaffs layout with the
  53  * pageStatus byte (at NAND spare offset 4) scattered/gathered from/to
  54  * the 9th byte.
  55  *
  56  * Old-style on-NAND format: T0,T1,T2,T3,P,B,T4,T5,E0,E1,E2,T6,T7,E3,E4,E5
  57  * We have/need PackedTags1 plus pageStatus: T0,T1,T2,T3,T4,T5,T6,T7,P
  58  * where Tn are the tag bytes, En are MTD's ECC bytes, P is the pageStatus
  59  * byte and B is the small-page bad-block indicator byte.
  60  */
  61 static struct nand_ecclayout nand_oob_16 = {
  62         .eccbytes = 6,
  63         .eccpos = { 8, 9, 10, 13, 14, 15 },
  64         .oobavail = 9,
  65         .oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
  66 };
  67 #endif
  68
  69 /* Write a chunk (page) of data to NAND.
  70  *
  71  * Caller always provides ExtendedTags data which are converted to a more
  72  * compact (packed) form for storage in NAND.  A mini-ECC runs over the
  73  * contents of the tags meta-data; used to valid the tags when read.
  74  *
  75  *  - Pack ExtendedTags to PackedTags1 form
  76  *  - Compute mini-ECC for PackedTags1
  77  *  - Write data and packed tags to NAND.
  78  *
  79  * Note: Due to the use of the PackedTags1 meta-data which does not include
  80  * a full sequence number (as found in the larger PackedTags2 form) it is
  81  * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
  82  * discarded and dirty.  This is not ideal: newer NAND parts are supposed
  83  * to be written just once.  When Yaffs performs this operation, this
  84  * function is called with a NULL data pointer -- calling MTD write_oob
  85  * without data is valid usage (2.6.17).
  86  *
  87  * Any underlying MTD error results in YAFFS_FAIL.
  88  * Returns YAFFS_OK or YAFFS_FAIL.
  89  */
  90 int nandmtd1_WriteChunkWithTagsToNAND(yaffs_Device *dev,
  91         int chunkInNAND, const __u8 * data, const yaffs_ExtendedTags * etags)
  92 {
  93         struct mtd_info * mtd = dev->genericDevice;
  94         int chunkBytes = dev->nDataBytesPerChunk;
  95         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
  96         struct mtd_oob_ops ops;
  97         yaffs_PackedTags1 pt1;
  98         int retval;
  99
 100         /* we assume that PackedTags1 and yaffs_Tags are compatible */
 101         compile_time_assertion(sizeof(yaffs_PackedTags1) == 12);
 102         compile_time_assertion(sizeof(yaffs_Tags) == 8);
 103
 104         dev->nPageWrites++;
 105
 106         yaffs_PackTags1(&pt1, etags);
 107         yaffs_CalcTagsECC((yaffs_Tags *)&pt1);
 108
 109         /* When deleting a chunk, the upper layer provides only skeletal
 110          * etags, one with chunkDeleted set.  However, we need to update the
 111          * tags, not erase them completely.  So we use the NAND write property
 112          * that only zeroed-bits stick and set tag bytes to all-ones and
 113          * zero just the (not) deleted bit.
 114          */
 115 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 116         if (etags->chunkDeleted) {
 117                 memset(&pt1, 0xff, 8);
 118                 /* clear delete status bit to indicate deleted */
 119                 pt1.deleted = 0;
 120         }
 121 #else
 122         ((__u8 *)&pt1)[8] = 0xff;
 123         if (etags->chunkDeleted) {
 124                 memset(&pt1, 0xff, 8);
 125                 /* zero pageStatus byte to indicate deleted */
 126                 ((__u8 *)&pt1)[8] = 0;
 127         }
 128 #endif
 129
 130         memset(&ops, 0, sizeof(ops));
 131         ops.mode = MTD_OOB_AUTO;
 132         ops.len = (data) ? chunkBytes : 0;
 133         ops.ooblen = YTAG1_SIZE;
 134         ops.datbuf = (__u8 *)data;
 135         ops.oobbuf = (__u8 *)&pt1;
 136
 137         retval = mtd->write_oob(mtd, addr, &ops);
 138         if (retval) {
 139                 yaffs_trace(YAFFS_TRACE_MTD,
 140                         "write_oob failed, chunk %d, mtd error %d\n",
 141                         chunkInNAND, retval);
 142         }
 143         return retval ? YAFFS_FAIL : YAFFS_OK;
 144 }
 145
 146 /* Return with empty ExtendedTags but add eccResult.
 147  */
 148 static int rettags(yaffs_ExtendedTags * etags, int eccResult, int retval)
 149 {
 150         if (etags) {
 151                 memset(etags, 0, sizeof(*etags));
 152                 etags->eccResult = eccResult;
 153         }
 154         return retval;
 155 }
 156
 157 /* Read a chunk (page) from NAND.
 158  *
 159  * Caller expects ExtendedTags data to be usable even on error; that is,
 160  * all members except eccResult and blockBad are zeroed.
 161  *
 162  *  - Check ECC results for data (if applicable)
 163  *  - Check for blank/erased block (return empty ExtendedTags if blank)
 164  *  - Check the PackedTags1 mini-ECC (correct if necessary/possible)
 165  *  - Convert PackedTags1 to ExtendedTags
 166  *  - Update eccResult and blockBad members to refect state.
 167  *
 168  * Returns YAFFS_OK or YAFFS_FAIL.
 169  */
 170 int nandmtd1_ReadChunkWithTagsFromNAND(yaffs_Device *dev,
 171         int chunkInNAND, __u8 * data, yaffs_ExtendedTags * etags)
 172 {
 173         struct mtd_info * mtd = dev->genericDevice;
 174         int chunkBytes = dev->nDataBytesPerChunk;
 175         loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
 176         int eccres = YAFFS_ECC_RESULT_NO_ERROR;
 177         struct mtd_oob_ops ops;
 178         yaffs_PackedTags1 pt1;
 179         int retval;
 180         int deleted;
 181
 182         dev->nPageReads++;
 183
 184         memset(&ops, 0, sizeof(ops));
 185         ops.mode = MTD_OOB_AUTO;
 186         ops.len = (data) ? chunkBytes : 0;
 187         ops.ooblen = YTAG1_SIZE;
 188         ops.datbuf = data;
 189         ops.oobbuf = (__u8 *)&pt1;
 190
 191 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,20))
 192         /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
 193          * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
 194          */
 195         ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
 196 #endif
 197         /* Read page and oob using MTD.
 198          * Check status and determine ECC result.
 199          */
 200         retval = mtd->read_oob(mtd, addr, &ops);
 201         if (retval) {
 202                 yaffs_trace(YAFFS_TRACE_MTD,
 203                         "read_oob failed, chunk %d, mtd error %d\n",
 204                         chunkInNAND, retval);
 205         }
 206
 207         switch (retval) {
 208         case 0:
 209                 /* no error */
 210                 break;
 211
 212         case -EUCLEAN:
 213                 /* MTD's ECC fixed the data */
 214                 eccres = YAFFS_ECC_RESULT_FIXED;
 215                 dev->eccFixed++;
 216                 break;
 217
 218         case -EBADMSG:
 219                 /* MTD's ECC could not fix the data */
 220                 dev->eccUnfixed++;
 221                 /* fall into... */
 222         default:
 223                 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
 224                 etags->blockBad = (mtd->block_isbad)(mtd, addr);
 225                 return YAFFS_FAIL;
 226         }
 227
 228         /* Check for a blank/erased chunk.
 229          */
 230         if (yaffs_CheckFF((__u8 *)&pt1, 8)) {
 231                 /* when blank, upper layers want eccResult to be <= NO_ERROR */
 232                 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
 233         }
 234
 235 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 236         /* Read deleted status (bit) then return it to it's non-deleted
 237          * state before performing tags mini-ECC check. pt1.deleted is
 238          * inverted.
 239          */
 240         deleted = !pt1.deleted;
 241         pt1.deleted = 1;
 242 #else
 243         deleted = (yaffs_CountBits(((__u8 *)&pt1)[8]) < 7);
 244 #endif
 245
 246         /* Check the packed tags mini-ECC and correct if necessary/possible.
 247          */
 248         retval = yaffs_CheckECCOnTags((yaffs_Tags *)&pt1);
 249         switch (retval) {
 250         case 0:
 251                 /* no tags error, use MTD result */
 252                 break;
 253         case 1:
 254                 /* recovered tags-ECC error */
 255                 dev->tagsEccFixed++;
 256                 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
 257                         eccres = YAFFS_ECC_RESULT_FIXED;
 258                 break;
 259         default:
 260                 /* unrecovered tags-ECC error */
 261                 dev->tagsEccUnfixed++;
 262                 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
 263         }
 264
 265         /* Unpack the tags to extended form and set ECC result.
 266          * [set shouldBeFF just to keep yaffs_UnpackTags1 happy]
 267          */
 268         pt1.shouldBeFF = 0xFFFFFFFF;
 269         yaffs_UnpackTags1(etags, &pt1);
 270         etags->eccResult = eccres;
 271
 272         /* Set deleted state */
 273         etags->chunkDeleted = deleted;
 274         return YAFFS_OK;
 275 }
 276
 277 /* Mark a block bad.
 278  *
 279  * This is a persistant state.
 280  * Use of this function should be rare.
 281  *
 282  * Returns YAFFS_OK or YAFFS_FAIL.
 283  */
 284 int nandmtd1_MarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockNo)
 285 {
 286         struct mtd_info * mtd = dev->genericDevice;
 287         int blocksize = dev->nChunksPerBlock * dev->nDataBytesPerChunk;
 288         int retval;
 289
 290         yaffs_trace(YAFFS_TRACE_BAD_BLOCKS, "marking block %d bad", blockNo);
 291
 292         retval = mtd->block_markbad(mtd, (loff_t)blocksize * blockNo);
 293         return (retval) ? YAFFS_FAIL : YAFFS_OK;
 294 }
 295
 296 /* Check any MTD prerequists.
 297  *
 298  * Returns YAFFS_OK or YAFFS_FAIL.
 299  */
 300 static int nandmtd1_TestPrerequists(struct mtd_info * mtd)
 301 {
 302         /* 2.6.18 has mtd->ecclayout->oobavail */
 303         /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
 304         int oobavail = mtd->ecclayout->oobavail;
 305
 306         if (oobavail < YTAG1_SIZE) {
 307                 yaffs_trace(YAFFS_TRACE_ERROR,
 308                         "mtd device has only %d bytes for tags, need %d\n",
 309                         oobavail, YTAG1_SIZE);
 310                 return YAFFS_FAIL;
 311         }
 312         return YAFFS_OK;
 313 }
 314
 315 /* Query for the current state of a specific block.
 316  *
 317  * Examine the tags of the first chunk of the block and return the state:
 318  *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
 319  *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
 320  *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
 321  *
 322  * Always returns YAFFS_OK.
 323  */
 324 int nandmtd1_QueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo,
 325         yaffs_BlockState * pState, int *pSequenceNumber)
 326 {
 327         struct mtd_info * mtd = dev->genericDevice;
 328         int chunkNo = blockNo * dev->nChunksPerBlock;
 329         yaffs_ExtendedTags etags;
 330         int state = YAFFS_BLOCK_STATE_DEAD;
 331         int seqnum = 0;
 332         int retval;
 333
 334         /* We don't yet have a good place to test for MTD config prerequists.
 335          * Do it here as we are called during the initial scan.
 336          */
 337         if (nandmtd1_TestPrerequists(mtd) != YAFFS_OK) {
 338                 return YAFFS_FAIL;
 339         }
 340
 341         retval = nandmtd1_ReadChunkWithTagsFromNAND(dev, chunkNo, NULL, &etags);
 342         if (etags.blockBad) {
 343                 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
 344                         "block %d is marked bad", blockNo);
 345                 state = YAFFS_BLOCK_STATE_DEAD;
 346         }
 347         else if (etags.chunkUsed) {
 348                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 349                 seqnum = etags.sequenceNumber;
 350         }
 351         else {
 352                 state = YAFFS_BLOCK_STATE_EMPTY;
 353         }
 354
 355         *pState = state;
 356         *pSequenceNumber = seqnum;
 357
 358         /* query always succeeds */
 359         return YAFFS_OK;
 360 }
 361
 362 #endif /*KERNEL_VERSION*/