drivers/mtd/onenand/onenand_bbt.c

   1 /*
   2  *  linux/drivers/mtd/onenand/onenand_bbt.c
   3  *
   4  *  Bad Block Table support for the OneNAND driver
   5  *
   6  *  Copyright(c) 2005 Samsung Electronics
   7  *  Kyungmin Park <kyungmin.park@samsung.com>
   8  *
   9  *  Derived from nand_bbt.c
  10  *
  11  *  TODO:
  12  *    Split BBT core and chip specific BBT.
  13  */
  14
  15 #include <linux/slab.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/mtd/onenand.h>
  18
  19 /**
  20  * check_short_pattern - [GENERIC] check if a pattern is in the buffer
  21  * @param buf           the buffer to search
  22  * @param len           the length of buffer to search
  23  * @param paglen        the pagelength
  24  * @param td            search pattern descriptor
  25  *
  26  * Check for a pattern at the given place. Used to search bad block
  27  * tables and good / bad block identifiers. Same as check_pattern, but
  28  * no optional empty check and the pattern is expected to start
  29  * at offset 0.
  30  *
  31  */
  32 static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
  33 {
  34         int i;
  35         uint8_t *p = buf;
  36
  37         /* Compare the pattern */
  38         for (i = 0; i < td->len; i++) {
  39                 if (p[i] != td->pattern[i])
  40                         return -1;
  41         }
  42         return 0;
  43 }
  44
  45 /**
  46  * create_bbt - [GENERIC] Create a bad block table by scanning the device
  47  * @param mtd           MTD device structure
  48  * @param buf           temporary buffer
  49  * @param bd            descriptor for the good/bad block search pattern
  50  * @param chip          create the table for a specific chip, -1 read all chips.
  51  *              Applies only if NAND_BBT_PERCHIP option is set
  52  *
  53  * Create a bad block table by scanning the device
  54  * for the given good/bad block identify pattern
  55  */
  56 static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
  57 {
  58         struct onenand_chip *this = mtd->priv;
  59         struct bbm_info *bbm = this->bbm;
  60         int i, j, numblocks, len, scanlen;
  61         int startblock;
  62         loff_t from;
  63         size_t readlen, ooblen;
  64         struct mtd_oob_ops ops;
  65         int rgn;
  66
  67         printk(KERN_INFO "Scanning device for bad blocks\n");
  68
  69         len = 2;
  70
  71         /* We need only read few bytes from the OOB area */
  72         scanlen = ooblen = 0;
  73         readlen = bd->len;
  74
  75         /* chip == -1 case only */
  76         /* Note that numblocks is 2 * (real numblocks) here;
  77          * see i += 2 below as it makses shifting and masking less painful
  78          */
  79         numblocks = this->chipsize >> (bbm->bbt_erase_shift - 1);
  80         startblock = 0;
  81         from = 0;
  82
  83         ops.mode = MTD_OOB_PLACE;
  84         ops.ooblen = readlen;
  85         ops.oobbuf = buf;
  86         ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
  87
  88         for (i = startblock; i < numblocks; ) {
  89                 int ret;
  90
  91                 for (j = 0; j < len; j++) {
  92                         /* No need to read pages fully,
  93                          * just read required OOB bytes */
  94                         ret = onenand_bbt_read_oob(mtd, from + j * mtd->writesize + bd->offs, &ops);
  95
  96                         /* If it is a initial bad block, just ignore it */
  97                         if (ret == ONENAND_BBT_READ_FATAL_ERROR)
  98                                 return -EIO;
  99
 100                         if (ret || check_short_pattern(&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
 101                                 bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
 102                                 printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
 103                                         i >> 1, (unsigned int) from);
 104                                 mtd->ecc_stats.badblocks++;
 105                                 break;
 106                         }
 107                 }
 108                 i += 2;
 109
 110                 if (FLEXONENAND(this)) {
 111                         rgn = flexonenand_region(mtd, from);
 112                         from += mtd->eraseregions[rgn].erasesize;
 113                 } else
 114                         from += (1 << bbm->bbt_erase_shift);
 115         }
 116
 117         return 0;
 118 }
 119
 120
 121 /**
 122  * onenand_memory_bbt - [GENERIC] create a memory based bad block table
 123  * @param mtd           MTD device structure
 124  * @param bd            descriptor for the good/bad block search pattern
 125  *
 126  * The function creates a memory based bbt by scanning the device
 127  * for manufacturer / software marked good / bad blocks
 128  */
 129 static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
 130 {
 131         struct onenand_chip *this = mtd->priv;
 132
 133         bd->options &= ~NAND_BBT_SCANEMPTY;
 134         return create_bbt(mtd, this->page_buf, bd, -1);
 135 }
 136
 137 /**
 138  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
 139  * @param mtd           MTD device structure
 140  * @param offs          offset in the device
 141  * @param allowbbt      allow access to bad block table region
 142  */
 143 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
 144 {
 145         struct onenand_chip *this = mtd->priv;
 146         struct bbm_info *bbm = this->bbm;
 147         int block;
 148         uint8_t res;
 149
 150         /* Get block number * 2 */
 151         block = (int) (onenand_block(this, offs) << 1);
 152         res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
 153
 154         DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
 155                 (unsigned int) offs, block >> 1, res);
 156
 157         switch ((int) res) {
 158         case 0x00:      return 0;
 159         case 0x01:      return 1;
 160         case 0x02:      return allowbbt ? 0 : 1;
 161         }
 162
 163         return 1;
 164 }
 165
 166 /**
 167  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
 168  * @param mtd           MTD device structure
 169  * @param bd            descriptor for the good/bad block search pattern
 170  *
 171  * The function checks, if a bad block table(s) is/are already
 172  * available. If not it scans the device for manufacturer
 173  * marked good / bad blocks and writes the bad block table(s) to
 174  * the selected place.
 175  *
 176  * The bad block table memory is allocated here. It is freed
 177  * by the onenand_release function.
 178  *
 179  */
 180 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
 181 {
 182         struct onenand_chip *this = mtd->priv;
 183         struct bbm_info *bbm = this->bbm;
 184         int len, ret = 0;
 185
 186         len = this->chipsize >> (this->erase_shift + 2);
 187         /* Allocate memory (2bit per block) and clear the memory bad block table */
 188         bbm->bbt = kzalloc(len, GFP_KERNEL);
 189         if (!bbm->bbt) {
 190                 printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
 191                 return -ENOMEM;
 192         }
 193
 194         /* Set the bad block position */
 195         bbm->badblockpos = ONENAND_BADBLOCK_POS;
 196
 197         /* Set erase shift */
 198         bbm->bbt_erase_shift = this->erase_shift;
 199
 200         if (!bbm->isbad_bbt)
 201                 bbm->isbad_bbt = onenand_isbad_bbt;
 202
 203         /* Scan the device to build a memory based bad block table */
 204         if ((ret = onenand_memory_bbt(mtd, bd))) {
 205                 printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
 206                 kfree(bbm->bbt);
 207                 bbm->bbt = NULL;
 208         }
 209
 210         return ret;
 211 }
 212
 213 /*
 214  * Define some generic bad / good block scan pattern which are used
 215  * while scanning a device for factory marked good / bad blocks.
 216  */
 217 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
 218
 219 static struct nand_bbt_descr largepage_memorybased = {
 220         .options = 0,
 221         .offs = 0,
 222         .len = 2,
 223         .pattern = scan_ff_pattern,
 224 };
 225
 226 /**
 227  * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
 228  * @param mtd           MTD device structure
 229  *
 230  * This function selects the default bad block table
 231  * support for the device and calls the onenand_scan_bbt function
 232  */
 233 int onenand_default_bbt(struct mtd_info *mtd)
 234 {
 235         struct onenand_chip *this = mtd->priv;
 236         struct bbm_info *bbm;
 237
 238         this->bbm = kzalloc(sizeof(struct bbm_info), GFP_KERNEL);
 239         if (!this->bbm)
 240                 return -ENOMEM;
 241
 242         bbm = this->bbm;
 243
 244         /* 1KB page has same configuration as 2KB page */
 245         if (!bbm->badblock_pattern)
 246                 bbm->badblock_pattern = &largepage_memorybased;
 247
 248         return onenand_scan_bbt(mtd, bbm->badblock_pattern);
 249 }
 250
 251 EXPORT_SYMBOL(onenand_scan_bbt);
 252 EXPORT_SYMBOL(onenand_default_bbt);