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