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_do_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
  21                                size_t *retlen, u_char *buf);
  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
  69         printk(KERN_INFO "Scanning device for bad blocks\n");
  70
  71         len = 1;
  72
  73         /* We need only read few bytes from the OOB area */
  74         scanlen = ooblen = 0;
  75         readlen = bd->len;
  76
  77         /* chip == -1 case only */
  78         /* Note that numblocks is 2 * (real numblocks) here;
  79          * see i += 2 below as it makses shifting and masking less painful
  80          */
  81         numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
  82         startblock = 0;
  83         from = 0;
  84
  85         for (i = startblock; i < numblocks; ) {
  86                 int ret;
  87
  88                 for (j = 0; j < len; j++) {
  89                         size_t retlen;
  90
  91                         /* No need to read pages fully,
  92                          * just read required OOB bytes */
  93                         ret = onenand_do_read_oob(mtd, from + j * mtd->writesize + bd->offs,
  94                                                   readlen, &retlen, &buf[0]);
  95
  96                         /* If it is a initial bad block, just ignore it */
  97                         if (ret && !(ret & ONENAND_CTRL_LOAD))
  98                                 return ret;
  99
 100                         if (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                 from += (1 << bbm->bbt_erase_shift);
 110         }
 111
 112         return 0;
 113 }
 114
 115
 116 /**
 117  * onenand_memory_bbt - [GENERIC] create a memory based bad block table
 118  * @param mtd           MTD device structure
 119  * @param bd            descriptor for the good/bad block search pattern
 120  *
 121  * The function creates a memory based bbt by scanning the device
 122  * for manufacturer / software marked good / bad blocks
 123  */
 124 static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
 125 {
 126         struct onenand_chip *this = mtd->priv;
 127
 128         bd->options &= ~NAND_BBT_SCANEMPTY;
 129         return create_bbt(mtd, this->page_buf, bd, -1);
 130 }
 131
 132 /**
 133  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
 134  * @param mtd           MTD device structure
 135  * @param offs          offset in the device
 136  * @param allowbbt      allow access to bad block table region
 137  */
 138 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
 139 {
 140         struct onenand_chip *this = mtd->priv;
 141         struct bbm_info *bbm = this->bbm;
 142         int block;
 143         uint8_t res;
 144
 145         /* Get block number * 2 */
 146         block = (int) (offs >> (bbm->bbt_erase_shift - 1));
 147         res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
 148
 149         DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
 150                 (unsigned int) offs, block >> 1, res);
 151
 152         switch ((int) res) {
 153         case 0x00:      return 0;
 154         case 0x01:      return 1;
 155         case 0x02:      return allowbbt ? 0 : 1;
 156         }
 157
 158         return 1;
 159 }
 160
 161 /**
 162  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
 163  * @param mtd           MTD device structure
 164  * @param bd            descriptor for the good/bad block search pattern
 165  *
 166  * The function checks, if a bad block table(s) is/are already
 167  * available. If not it scans the device for manufacturer
 168  * marked good / bad blocks and writes the bad block table(s) to
 169  * the selected place.
 170  *
 171  * The bad block table memory is allocated here. It must be freed
 172  * by calling the onenand_free_bbt function.
 173  *
 174  */
 175 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
 176 {
 177         struct onenand_chip *this = mtd->priv;
 178         struct bbm_info *bbm = this->bbm;
 179         int len, ret = 0;
 180
 181         len = mtd->size >> (this->erase_shift + 2);
 182         /* Allocate memory (2bit per block) and clear the memory bad block table */
 183         bbm->bbt = kzalloc(len, GFP_KERNEL);
 184         if (!bbm->bbt) {
 185                 printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
 186                 return -ENOMEM;
 187         }
 188
 189         /* Set the bad block position */
 190         bbm->badblockpos = ONENAND_BADBLOCK_POS;
 191
 192         /* Set erase shift */
 193         bbm->bbt_erase_shift = this->erase_shift;
 194
 195         if (!bbm->isbad_bbt)
 196                 bbm->isbad_bbt = onenand_isbad_bbt;
 197
 198         /* Scan the device to build a memory based bad block table */
 199         if ((ret = onenand_memory_bbt(mtd, bd))) {
 200                 printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
 201                 kfree(bbm->bbt);
 202                 bbm->bbt = NULL;
 203         }
 204
 205         return ret;
 206 }
 207
 208 /*
 209  * Define some generic bad / good block scan pattern which are used
 210  * while scanning a device for factory marked good / bad blocks.
 211  */
 212 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
 213
 214 static struct nand_bbt_descr largepage_memorybased = {
 215         .options = 0,
 216         .offs = 0,
 217         .len = 2,
 218         .pattern = scan_ff_pattern,
 219 };
 220
 221 /**
 222  * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
 223  * @param mtd           MTD device structure
 224  *
 225  * This function selects the default bad block table
 226  * support for the device and calls the onenand_scan_bbt function
 227  */
 228 int onenand_default_bbt(struct mtd_info *mtd)
 229 {
 230         struct onenand_chip *this = mtd->priv;
 231         struct bbm_info *bbm;
 232
 233         this->bbm = kzalloc(sizeof(struct bbm_info), GFP_KERNEL);
 234         if (!this->bbm)
 235                 return -ENOMEM;
 236
 237         bbm = this->bbm;
 238
 239         /* 1KB page has same configuration as 2KB page */
 240         if (!bbm->badblock_pattern)
 241                 bbm->badblock_pattern = &largepage_memorybased;
 242
 243         return onenand_scan_bbt(mtd, bbm->badblock_pattern);
 244 }
 245
 246 EXPORT_SYMBOL(onenand_scan_bbt);
 247 EXPORT_SYMBOL(onenand_default_bbt);