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 #include <linux/export.h>
  19
  20 /**
  21  * check_short_pattern - [GENERIC] check if a pattern is in the buffer
  22  * @param buf           the buffer to search
  23  * @param len           the length of buffer to search
  24  * @param paglen        the pagelength
  25  * @param td            search pattern descriptor
  26  *
  27  * Check for a pattern at the given place. Used to search bad block
  28  * tables and good / bad block identifiers. Same as check_pattern, but
  29  * no optional empty check and the pattern is expected to start
  30  * at offset 0.
  31  *
  32  */
  33 static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
  34 {
  35         int i;
  36         uint8_t *p = buf;
  37
  38         /* Compare the pattern */
  39         for (i = 0; i < td->len; i++) {
  40                 if (p[i] != td->pattern[i])
  41                         return -1;
  42         }
  43         return 0;
  44 }
  45
  46 /**
  47  * create_bbt - [GENERIC] Create a bad block table by scanning the device
  48  * @param mtd           MTD device structure
  49  * @param buf           temporary buffer
  50  * @param bd            descriptor for the good/bad block search pattern
  51  * @param chip          create the table for a specific chip, -1 read all chips.
  52  *              Applies only if NAND_BBT_PERCHIP option is set
  53  *
  54  * Create a bad block table by scanning the device
  55  * for the given good/bad block identify pattern
  56  */
  57 static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
  58 {
  59         struct onenand_chip *this = mtd->priv;
  60         struct bbm_info *bbm = this->bbm;
  61         int i, j, numblocks, len, scanlen;
  62         int startblock;
  63         loff_t from;
  64         size_t readlen, ooblen;
  65         struct mtd_oob_ops ops;
  66         int rgn;
  67
  68         printk(KERN_INFO "Scanning device for bad blocks\n");
  69
  70         len = 2;
  71
  72         /* We need only read few bytes from the OOB area */
  73         scanlen = ooblen = 0;
  74         readlen = bd->len;
  75
  76         /* chip == -1 case only */
  77         /* Note that numblocks is 2 * (real numblocks) here;
  78          * see i += 2 below as it makses shifting and masking less painful
  79          */
  80         numblocks = this->chipsize >> (bbm->bbt_erase_shift - 1);
  81         startblock = 0;
  82         from = 0;
  83
  84         ops.mode = MTD_OPS_PLACE_OOB;
  85         ops.ooblen = readlen;
  86         ops.oobbuf = buf;
  87         ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
  88
  89         for (i = startblock; i < numblocks; ) {
  90                 int ret;
  91
  92                 for (j = 0; j < len; j++) {
  93                         /* No need to read pages fully,
  94                          * just read required OOB bytes */
  95                         ret = onenand_bbt_read_oob(mtd,
  96                                 from + j * this->writesize + bd->offs, &ops);
  97
  98                         /* If it is a initial bad block, just ignore it */
  99                         if (ret == ONENAND_BBT_READ_FATAL_ERROR)
 100                                 return -EIO;
 101
 102                         if (ret || check_short_pattern(&buf[j * scanlen],
 103                                                scanlen, this->writesize, bd)) {
 104                                 bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
 105                                 printk(KERN_INFO "OneNAND eraseblock %d is an "
 106                                         "initial bad block\n", i >> 1);
 107                                 mtd->ecc_stats.badblocks++;
 108                                 break;
 109                         }
 110                 }
 111                 i += 2;
 112
 113                 if (FLEXONENAND(this)) {
 114                         rgn = flexonenand_region(mtd, from);
 115                         from += mtd->eraseregions[rgn].erasesize;
 116                 } else
 117                         from += (1 << bbm->bbt_erase_shift);
 118         }
 119
 120         return 0;
 121 }
 122
 123
 124 /**
 125  * onenand_memory_bbt - [GENERIC] create a memory based bad block table
 126  * @param mtd           MTD device structure
 127  * @param bd            descriptor for the good/bad block search pattern
 128  *
 129  * The function creates a memory based bbt by scanning the device
 130  * for manufacturer / software marked good / bad blocks
 131  */
 132 static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
 133 {
 134         struct onenand_chip *this = mtd->priv;
 135
 136         return create_bbt(mtd, this->page_buf, bd, -1);
 137 }
 138
 139 /**
 140  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
 141  * @param mtd           MTD device structure
 142  * @param offs          offset in the device
 143  * @param allowbbt      allow access to bad block table region
 144  */
 145 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
 146 {
 147         struct onenand_chip *this = mtd->priv;
 148         struct bbm_info *bbm = this->bbm;
 149         int block;
 150         uint8_t res;
 151
 152         /* Get block number * 2 */
 153         block = (int) (onenand_block(this, offs) << 1);
 154         res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
 155
 156         pr_debug("onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
 157                 (unsigned int) offs, block >> 1, res);
 158
 159         switch ((int) res) {
 160         case 0x00:      return 0;
 161         case 0x01:      return 1;
 162         case 0x02:      return allowbbt ? 0 : 1;
 163         }
 164
 165         return 1;
 166 }
 167
 168 /**
 169  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
 170  * @param mtd           MTD device structure
 171  * @param bd            descriptor for the good/bad block search pattern
 172  *
 173  * The function checks, if a bad block table(s) is/are already
 174  * available. If not it scans the device for manufacturer
 175  * marked good / bad blocks and writes the bad block table(s) to
 176  * the selected place.
 177  *
 178  * The bad block table memory is allocated here. It is freed
 179  * by the onenand_release function.
 180  *
 181  */
 182 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
 183 {
 184         struct onenand_chip *this = mtd->priv;
 185         struct bbm_info *bbm = this->bbm;
 186         int len, ret = 0;
 187
 188         len = this->chipsize >> (this->erase_shift + 2);
 189         /* Allocate memory (2bit per block) and clear the memory bad block table */
 190         bbm->bbt = kzalloc(len, GFP_KERNEL);
 191         if (!bbm->bbt)
 192                 return -ENOMEM;
 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);