fs/yaffs2/yaffs_mtdif1.c

   1 /*
   2  * YAFFS: Yet another FFS. A NAND-flash specific file system.
   3  *
   4  * Copyright (C) 2002-2010 Aleph One Ltd.
   5  *   for Toby Churchill Ltd and Brightstar Engineering
   6  *
   7  * Created by Charles Manning <charles@aleph1.co.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 /*
  15  * This module provides the interface between yaffs_nand.c and the
  16  * MTD API.  This version is used when the MTD interface supports the
  17  * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
  18  * and we have small-page NAND device.
  19  *
  20  * These functions are invoked via function pointers in yaffs_nand.c.
  21  * This replaces functionality provided by functions in yaffs_mtdif.c
  22  * and the yaffs_tags compatability functions in yaffs_tagscompat.c that are
  23  * called in yaffs_mtdif.c when the function pointers are NULL.
  24  * We assume the MTD layer is performing ECC (use_nand_ecc is true).
  25  */
  26
  27 #include "yportenv.h"
  28 #include "yaffs_trace.h"
  29 #include "yaffs_guts.h"
  30 #include "yaffs_packedtags1.h"
  31 #include "yaffs_tagscompat.h"   /* for yaffs_calc_tags_ecc */
  32 #include "yaffs_linux.h"
  33
  34 #include "linux/kernel.h"
  35 #include "linux/version.h"
  36 #include "linux/types.h"
  37 #include "linux/mtd/mtd.h"
  38
  39 #ifndef CONFIG_YAFFS_9BYTE_TAGS
  40 # define YTAG1_SIZE 8
  41 #else
  42 # define YTAG1_SIZE 9
  43 #endif
  44
  45 /* Write a chunk (page) of data to NAND.
  46  *
  47  * Caller always provides ExtendedTags data which are converted to a more
  48  * compact (packed) form for storage in NAND.  A mini-ECC runs over the
  49  * contents of the tags meta-data; used to valid the tags when read.
  50  *
  51  *  - Pack ExtendedTags to packed_tags1 form
  52  *  - Compute mini-ECC for packed_tags1
  53  *  - Write data and packed tags to NAND.
  54  *
  55  * Note: Due to the use of the packed_tags1 meta-data which does not include
  56  * a full sequence number (as found in the larger packed_tags2 form) it is
  57  * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
  58  * discarded and dirty.  This is not ideal: newer NAND parts are supposed
  59  * to be written just once.  When Yaffs performs this operation, this
  60  * function is called with a NULL data pointer -- calling MTD write_oob
  61  * without data is valid usage (2.6.17).
  62  *
  63  * Any underlying MTD error results in YAFFS_FAIL.
  64  * Returns YAFFS_OK or YAFFS_FAIL.
  65  */
  66 int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
  67                               int nand_chunk, const u8 * data,
  68                               const struct yaffs_ext_tags *etags)
  69 {
  70         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
  71         int chunk_bytes = dev->data_bytes_per_chunk;
  72         loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
  73         struct mtd_oob_ops ops;
  74         struct yaffs_packed_tags1 pt1;
  75         int retval;
  76
  77         /* we assume that packed_tags1 and struct yaffs_tags are compatible */
  78         compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
  79         compile_time_assertion(sizeof(struct yaffs_tags) == 8);
  80
  81         yaffs_pack_tags1(&pt1, etags);
  82         yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
  83
  84         /* When deleting a chunk, the upper layer provides only skeletal
  85          * etags, one with is_deleted set.  However, we need to update the
  86          * tags, not erase them completely.  So we use the NAND write property
  87          * that only zeroed-bits stick and set tag bytes to all-ones and
  88          * zero just the (not) deleted bit.
  89          */
  90 #ifndef CONFIG_YAFFS_9BYTE_TAGS
  91         if (etags->is_deleted) {
  92                 memset(&pt1, 0xff, 8);
  93                 /* clear delete status bit to indicate deleted */
  94                 pt1.deleted = 0;
  95         }
  96 #else
  97         ((u8 *) & pt1)[8] = 0xff;
  98         if (etags->is_deleted) {
  99                 memset(&pt1, 0xff, 8);
 100                 /* zero page_status byte to indicate deleted */
 101                 ((u8 *) & pt1)[8] = 0;
 102         }
 103 #endif
 104
 105         memset(&ops, 0, sizeof(ops));
 106         ops.mode = MTD_OOB_AUTO;
 107         ops.len = (data) ? chunk_bytes : 0;
 108         ops.ooblen = YTAG1_SIZE;
 109         ops.datbuf = (u8 *) data;
 110         ops.oobbuf = (u8 *) & pt1;
 111
 112         retval = mtd->write_oob(mtd, addr, &ops);
 113         if (retval) {
 114                 yaffs_trace(YAFFS_TRACE_MTD,
 115                         "write_oob failed, chunk %d, mtd error %d",
 116                         nand_chunk, retval);
 117         }
 118         return retval ? YAFFS_FAIL : YAFFS_OK;
 119 }
 120
 121 /* Return with empty ExtendedTags but add ecc_result.
 122  */
 123 static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
 124 {
 125         if (etags) {
 126                 memset(etags, 0, sizeof(*etags));
 127                 etags->ecc_result = ecc_result;
 128         }
 129         return retval;
 130 }
 131
 132 /* Read a chunk (page) from NAND.
 133  *
 134  * Caller expects ExtendedTags data to be usable even on error; that is,
 135  * all members except ecc_result and block_bad are zeroed.
 136  *
 137  *  - Check ECC results for data (if applicable)
 138  *  - Check for blank/erased block (return empty ExtendedTags if blank)
 139  *  - Check the packed_tags1 mini-ECC (correct if necessary/possible)
 140  *  - Convert packed_tags1 to ExtendedTags
 141  *  - Update ecc_result and block_bad members to refect state.
 142  *
 143  * Returns YAFFS_OK or YAFFS_FAIL.
 144  */
 145 int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
 146                              int nand_chunk, u8 * data,
 147                              struct yaffs_ext_tags *etags)
 148 {
 149         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 150         int chunk_bytes = dev->data_bytes_per_chunk;
 151         loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
 152         int eccres = YAFFS_ECC_RESULT_NO_ERROR;
 153         struct mtd_oob_ops ops;
 154         struct yaffs_packed_tags1 pt1;
 155         int retval;
 156         int deleted;
 157
 158         memset(&ops, 0, sizeof(ops));
 159         ops.mode = MTD_OOB_AUTO;
 160         ops.len = (data) ? chunk_bytes : 0;
 161         ops.ooblen = YTAG1_SIZE;
 162         ops.datbuf = data;
 163         ops.oobbuf = (u8 *) & pt1;
 164
 165         /* Read page and oob using MTD.
 166          * Check status and determine ECC result.
 167          */
 168         retval = mtd->read_oob(mtd, addr, &ops);
 169         if (retval) {
 170                 yaffs_trace(YAFFS_TRACE_MTD,
 171                         "read_oob failed, chunk %d, mtd error %d",
 172                         nand_chunk, retval);
 173         }
 174
 175         switch (retval) {
 176         case 0:
 177                 /* no error */
 178                 break;
 179
 180         case -EUCLEAN:
 181                 /* MTD's ECC fixed the data */
 182                 eccres = YAFFS_ECC_RESULT_FIXED;
 183                 dev->n_ecc_fixed++;
 184                 break;
 185
 186         case -EBADMSG:
 187                 /* MTD's ECC could not fix the data */
 188                 dev->n_ecc_unfixed++;
 189                 /* fall into... */
 190         default:
 191                 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
 192                 etags->block_bad = (mtd->block_isbad) (mtd, addr);
 193                 return YAFFS_FAIL;
 194         }
 195
 196         /* Check for a blank/erased chunk.
 197          */
 198         if (yaffs_check_ff((u8 *) & pt1, 8)) {
 199                 /* when blank, upper layers want ecc_result to be <= NO_ERROR */
 200                 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
 201         }
 202 #ifndef CONFIG_YAFFS_9BYTE_TAGS
 203         /* Read deleted status (bit) then return it to it's non-deleted
 204          * state before performing tags mini-ECC check. pt1.deleted is
 205          * inverted.
 206          */
 207         deleted = !pt1.deleted;
 208         pt1.deleted = 1;
 209 #else
 210         deleted = (yaffs_count_bits(((u8 *) & pt1)[8]) < 7);
 211 #endif
 212
 213         /* Check the packed tags mini-ECC and correct if necessary/possible.
 214          */
 215         retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
 216         switch (retval) {
 217         case 0:
 218                 /* no tags error, use MTD result */
 219                 break;
 220         case 1:
 221                 /* recovered tags-ECC error */
 222                 dev->n_tags_ecc_fixed++;
 223                 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
 224                         eccres = YAFFS_ECC_RESULT_FIXED;
 225                 break;
 226         default:
 227                 /* unrecovered tags-ECC error */
 228                 dev->n_tags_ecc_unfixed++;
 229                 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
 230         }
 231
 232         /* Unpack the tags to extended form and set ECC result.
 233          * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
 234          */
 235         pt1.should_be_ff = 0xFFFFFFFF;
 236         yaffs_unpack_tags1(etags, &pt1);
 237         etags->ecc_result = eccres;
 238
 239         /* Set deleted state */
 240         etags->is_deleted = deleted;
 241         return YAFFS_OK;
 242 }
 243
 244 /* Mark a block bad.
 245  *
 246  * This is a persistant state.
 247  * Use of this function should be rare.
 248  *
 249  * Returns YAFFS_OK or YAFFS_FAIL.
 250  */
 251 int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
 252 {
 253         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 254         int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
 255         int retval;
 256
 257         yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
 258                 "marking block %d bad", block_no);
 259
 260         retval = mtd->block_markbad(mtd, (loff_t) blocksize * block_no);
 261         return (retval) ? YAFFS_FAIL : YAFFS_OK;
 262 }
 263
 264 /* Check any MTD prerequists.
 265  *
 266  * Returns YAFFS_OK or YAFFS_FAIL.
 267  */
 268 static int nandmtd1_test_prerequists(struct mtd_info *mtd)
 269 {
 270         /* 2.6.18 has mtd->ecclayout->oobavail */
 271         /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
 272         int oobavail = mtd->ecclayout->oobavail;
 273
 274         if (oobavail < YTAG1_SIZE) {
 275                 yaffs_trace(YAFFS_TRACE_ERROR,
 276                         "mtd device has only %d bytes for tags, need %d",
 277                         oobavail, YTAG1_SIZE);
 278                 return YAFFS_FAIL;
 279         }
 280         return YAFFS_OK;
 281 }
 282
 283 /* Query for the current state of a specific block.
 284  *
 285  * Examine the tags of the first chunk of the block and return the state:
 286  *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
 287  *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
 288  *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
 289  *
 290  * Always returns YAFFS_OK.
 291  */
 292 int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
 293                          enum yaffs_block_state *state_ptr, u32 * seq_ptr)
 294 {
 295         struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
 296         int chunk_num = block_no * dev->param.chunks_per_block;
 297         loff_t addr = (loff_t) chunk_num * dev->data_bytes_per_chunk;
 298         struct yaffs_ext_tags etags;
 299         int state = YAFFS_BLOCK_STATE_DEAD;
 300         int seqnum = 0;
 301         int retval;
 302
 303         /* We don't yet have a good place to test for MTD config prerequists.
 304          * Do it here as we are called during the initial scan.
 305          */
 306         if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
 307                 return YAFFS_FAIL;
 308
 309         retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
 310         etags.block_bad = (mtd->block_isbad) (mtd, addr);
 311         if (etags.block_bad) {
 312                 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
 313                         "block %d is marked bad", block_no);
 314                 state = YAFFS_BLOCK_STATE_DEAD;
 315         } else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
 316                 /* bad tags, need to look more closely */
 317                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 318         } else if (etags.chunk_used) {
 319                 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
 320                 seqnum = etags.seq_number;
 321         } else {
 322                 state = YAFFS_BLOCK_STATE_EMPTY;
 323         }
 324
 325         *state_ptr = state;
 326         *seq_ptr = seqnum;
 327
 328         /* query always succeeds */
 329         return YAFFS_OK;
 330 }