target/linux/generic/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) 2002-2010 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_tags_tCompatability 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 (use_nand_ecc is true).
  24  */
  25
  26 #include "yportenv.h"
  27 #include "yaffs_trace.h"
  28 #include "yaffs_guts.h"
  29 #include "yaffs_packedtags1.h"
  30 #include "yaffs_tagscompat.h"   /* for yaffs_calc_tags_ecc */
  31 #include "yaffs_linux.h"
  32
  33 #include "linux/kernel.h"
  34 #include "linux/version.h"
  35 #include "linux/types.h"
  36 #include "linux/mtd/mtd.h"
  37
  38 /* Don't compile this module if we don't have MTD's mtd_oob_ops interface */
  39 #if (MTD_VERSION_CODE > MTD_VERSION(2, 6, 17))
  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  * page_status 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 page_status: 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 page_status
  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_dev_t *dev,
  92         int nand_chunk, const __u8 *data, const yaffs_ext_tags *etags)
  93 {
  94         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
  95         int chunkBytes = dev->data_bytes_per_chunk;
  96         loff_t addr = ((loff_t)nand_chunk) * chunkBytes;
  97         struct mtd_oob_ops ops;
  98         yaffs_PackedTags1 pt1;
  99         int retval;
 100
 101         /* we assume that PackedTags1 and yaffs_tags_t are compatible */
 102         compile_time_assertion(sizeof(yaffs_PackedTags1) == 12);
 103         compile_time_assertion(sizeof(yaffs_tags_t) == 8);
 104
 105         yaffs_PackTags1(&pt1, etags);
 106         yaffs_calc_tags_ecc((yaffs_tags_t *)&pt1);
 107
 108         /* When deleting a chunk, the upper layer provides only skeletal
 109          * etags, one with is_deleted set.  However, we need to update the
 110          * tags, not erase them completely.  So we use the NAND write property
 111          * that only zeroed-bits stick and set tag bytes to all-ones and
 112          * zero just the (not) deleted bit.
 113          */
 114 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 115         if (etags->is_deleted) {
 116                 memset(&pt1, 0xff, 8);
 117                 /* clear delete status bit to indicate deleted */
 118                 pt1.deleted = 0;
 119         }
 120 #else
 121         ((__u8 *)&pt1)[8] = 0xff;
 122         if (etags->is_deleted) {
 123                 memset(&pt1, 0xff, 8);
 124                 /* zero page_status byte to indicate deleted */
 125                 ((__u8 *)&pt1)[8] = 0;
 126         }
 127 #endif
 128
 129         memset(&ops, 0, sizeof(ops));
 130         ops.mode = MTD_OOB_AUTO;
 131         ops.len = (data) ? chunkBytes : 0;
 132         ops.ooblen = YTAG1_SIZE;
 133         ops.datbuf = (__u8 *)data;
 134         ops.oobbuf = (__u8 *)&pt1;
 135
 136         retval = mtd->write_oob(mtd, addr, &ops);
 137         if (retval) {
 138                 T(YAFFS_TRACE_MTD,
 139                         (TSTR("write_oob failed, chunk %d, mtd error %d"TENDSTR),
 140                         nand_chunk, retval));
 141         }
 142         return retval ? YAFFS_FAIL : YAFFS_OK;
 143 }
 144
 145 /* Return with empty ExtendedTags but add ecc_result.
 146  */
 147 static int rettags(yaffs_ext_tags *etags, int ecc_result, int retval)
 148 {
 149         if (etags) {
 150                 memset(etags, 0, sizeof(*etags));
 151                 etags->ecc_result = ecc_result;
 152         }
 153         return retval;
 154 }
 155
 156 /* Read a chunk (page) from NAND.
 157  *
 158  * Caller expects ExtendedTags data to be usable even on error; that is,
 159  * all members except ecc_result and block_bad are zeroed.
 160  *
 161  *  - Check ECC results for data (if applicable)
 162  *  - Check for blank/erased block (return empty ExtendedTags if blank)
 163  *  - Check the PackedTags1 mini-ECC (correct if necessary/possible)
 164  *  - Convert PackedTags1 to ExtendedTags
 165  *  - Update ecc_result and block_bad members to refect state.
 166  *
 167  * Returns YAFFS_OK or YAFFS_FAIL.
 168  */
 169 int nandmtd1_ReadChunkWithTagsFromNAND(yaffs_dev_t *dev,
 170         int nand_chunk, __u8 *data, yaffs_ext_tags *etags)
 171 {
 172         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 173         int chunkBytes = dev->data_bytes_per_chunk;
 174         loff_t addr = ((loff_t)nand_chunk) * chunkBytes;
 175         int eccres = YAFFS_ECC_RESULT_NO_ERROR;
 176         struct mtd_oob_ops ops;
 177         yaffs_PackedTags1 pt1;
 178         int retval;
 179         int deleted;
 180
 181         memset(&ops, 0, sizeof(ops));
 182         ops.mode = MTD_OOB_AUTO;
 183         ops.len = (data) ? chunkBytes : 0;
 184         ops.ooblen = YTAG1_SIZE;
 185         ops.datbuf = data;
 186         ops.oobbuf = (__u8 *)&pt1;
 187
 188 #if (MTD_VERSION_CODE < MTD_VERSION(2, 6, 20))
 189         /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
 190          * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
 191          */
 192         ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
 193 #endif
 194         /* Read page and oob using MTD.
 195          * Check status and determine ECC result.
 196          */
 197         retval = mtd->read_oob(mtd, addr, &ops);
 198         if (retval) {
 199                 T(YAFFS_TRACE_MTD,
 200                         (TSTR("read_oob failed, chunk %d, mtd error %d"TENDSTR),
 201                         nand_chunk, retval));
 202         }
 203
 204         switch (retval) {
 205         case 0:
 206                 /* no error */
 207                 break;
 208
 209         case -EUCLEAN:
 210                 /* MTD's ECC fixed the data */
 211                 eccres = YAFFS_ECC_RESULT_FIXED;
 212                 dev->n_ecc_fixed++;
 213                 break;
 214
 215         case -EBADMSG:
 216                 /* MTD's ECC could not fix the data */
 217                 dev->n_ecc_unfixed++;
 218                 /* fall into... */
 219         default:
 220                 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
 221                 etags->block_bad = (mtd->block_isbad)(mtd, addr);
 222                 return YAFFS_FAIL;
 223         }
 224
 225         /* Check for a blank/erased chunk.
 226          */
 227         if (yaffs_check_ff((__u8 *)&pt1, 8)) {
 228                 /* when blank, upper layers want ecc_result to be <= NO_ERROR */
 229                 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
 230         }
 231
 232 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 233         /* Read deleted status (bit) then return it to it's non-deleted
 234          * state before performing tags mini-ECC check. pt1.deleted is
 235          * inverted.
 236          */
 237         deleted = !pt1.deleted;
 238         pt1.deleted = 1;
 239 #else
 240         deleted = (yaffs_count_bits(((__u8 *)&pt1)[8]) < 7);
 241 #endif
 242
 243         /* Check the packed tags mini-ECC and correct if necessary/possible.
 244          */
 245         retval = yaffs_check_tags_ecc((yaffs_tags_t *)&pt1);
 246         switch (retval) {
 247         case 0:
 248                 /* no tags error, use MTD result */
 249                 break;
 250         case 1:
 251                 /* recovered tags-ECC error */
 252                 dev->n_tags_ecc_fixed++;
 253                 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
 254                         eccres = YAFFS_ECC_RESULT_FIXED;
 255                 break;
 256         default:
 257                 /* unrecovered tags-ECC error */
 258                 dev->n_tags_ecc_unfixed++;
 259                 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
 260         }
 261
 262         /* Unpack the tags to extended form and set ECC result.
 263          * [set shouldBeFF just to keep yaffs_unpack_tags1 happy]
 264          */
 265         pt1.shouldBeFF = 0xFFFFFFFF;
 266         yaffs_unpack_tags1(etags, &pt1);
 267         etags->ecc_result = eccres;
 268
 269         /* Set deleted state */
 270         etags->is_deleted = deleted;
 271         return YAFFS_OK;
 272 }
 273
 274 /* Mark a block bad.
 275  *
 276  * This is a persistant state.
 277  * Use of this function should be rare.
 278  *
 279  * Returns YAFFS_OK or YAFFS_FAIL.
 280  */
 281 int nandmtd1_MarkNANDBlockBad(struct yaffs_dev_s *dev, int block_no)
 282 {
 283         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 284         int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
 285         int retval;
 286
 287         T(YAFFS_TRACE_BAD_BLOCKS,(TSTR("marking block %d bad"TENDSTR), block_no));
 288
 289         retval = mtd->block_markbad(mtd, (loff_t)blocksize * block_no);
 290         return (retval) ? YAFFS_FAIL : YAFFS_OK;
 291 }
 292
 293 /* Check any MTD prerequists.
 294  *
 295  * Returns YAFFS_OK or YAFFS_FAIL.
 296  */
 297 static int nandmtd1_TestPrerequists(struct mtd_info *mtd)
 298 {
 299         /* 2.6.18 has mtd->ecclayout->oobavail */
 300         /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
 301         int oobavail = mtd->ecclayout->oobavail;
 302
 303         if (oobavail < YTAG1_SIZE) {
 304                 T(YAFFS_TRACE_ERROR,
 305                         (TSTR("mtd device has only %d bytes for tags, need %d"TENDSTR),
 306                         oobavail, YTAG1_SIZE));
 307                 return YAFFS_FAIL;
 308         }
 309         return YAFFS_OK;
 310 }
 311
 312 /* Query for the current state of a specific block.
 313  *
 314  * Examine the tags of the first chunk of the block and return the state:
 315  *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
 316  *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
 317  *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
 318  *
 319  * Always returns YAFFS_OK.
 320  */
 321 int nandmtd1_QueryNANDBlock(struct yaffs_dev_s *dev, int block_no,
 322         yaffs_block_state_t *pState, __u32 *pSequenceNumber)
 323 {
 324         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 325         int chunkNo = block_no * dev->param.chunks_per_block;
 326         loff_t addr = (loff_t)chunkNo * dev->data_bytes_per_chunk;
 327         yaffs_ext_tags etags;
 328         int state = YAFFS_BLOCK_STATE_DEAD;
 329         int seqnum = 0;
 330         int retval;
 331
 332         /* We don't yet have a good place to test for MTD config prerequists.
 333          * Do it here as we are called during the initial scan.
 334          */
 335         if (nandmtd1_TestPrerequists(mtd) != YAFFS_OK)
 336                 return YAFFS_FAIL;
 337
 338         retval = nandmtd1_ReadChunkWithTagsFromNAND(dev, chunkNo, NULL, &etags);
 339         etags.block_bad = (mtd->block_isbad)(mtd, addr);
 340         if (etags.block_bad) {
 341                 T(YAFFS_TRACE_BAD_BLOCKS,
 342                         (TSTR("block %d is marked bad"TENDSTR), block_no));
 343                 state = YAFFS_BLOCK_STATE_DEAD;
 344         } else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
 345                 /* bad tags, need to look more closely */
 346                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 347         } else if (etags.chunk_used) {
 348                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 349                 seqnum = etags.seq_number;
 350         } else {
 351                 state = YAFFS_BLOCK_STATE_EMPTY;
 352         }
 353
 354         *pState = state;
 355         *pSequenceNumber = seqnum;
 356
 357         /* query always succeeds */
 358         return YAFFS_OK;
 359 }
 360
 361 #endif /*MTD_VERSION*/