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 /**
  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
  66         printk(KERN_INFO "Scanning device for bad blocks\n");
  67
  68         len = 1;
  69
  70         /* We need only read few bytes from the OOB area */
  71         scanlen = ooblen = 0;
  72         readlen = bd->len;
  73
  74         /* chip == -1 case only */
  75         /* Note that numblocks is 2 * (real numblocks) here;
  76          * see i += 2 below as it makses shifting and masking less painful
  77          */
  78         numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
  79         startblock = 0;
  80         from = 0;
  81
  82         for (i = startblock; i < numblocks; ) {
  83                 int ret;
  84
  85                 for (j = 0; j < len; j++) {
  86                         size_t retlen;
  87
  88                         /* No need to read pages fully,
  89                          * just read required OOB bytes */
  90                         ret = mtd->read_oob(mtd, from + j * mtd->oobblock + bd->offs,
  91                                                 readlen, &retlen, &buf[0]);
  92
  93                         if (ret)
  94                                 return ret;
  95
  96                         if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->oobblock, bd)) {
  97                                 bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
  98                                 printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
  99                                         i >> 1, (unsigned int) from);
 100                                 break;
 101                         }
 102                 }
 103                 i += 2;
 104                 from += (1 << bbm->bbt_erase_shift);
 105         }
 106
 107         return 0;
 108 }
 109
 110
 111 /**
 112  * onenand_memory_bbt - [GENERIC] create a memory based bad block table
 113  * @param mtd           MTD device structure
 114  * @param bd            descriptor for the good/bad block search pattern
 115  *
 116  * The function creates a memory based bbt by scanning the device
 117  * for manufacturer / software marked good / bad blocks
 118  */
 119 static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
 120 {
 121         unsigned char data_buf[MAX_ONENAND_PAGESIZE];
 122
 123         bd->options &= ~NAND_BBT_SCANEMPTY;
 124         return create_bbt(mtd, data_buf, bd, -1);
 125 }
 126
 127 /**
 128  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
 129  * @param mtd           MTD device structure
 130  * @param offs          offset in the device
 131  * @param allowbbt      allow access to bad block table region
 132  */
 133 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
 134 {
 135         struct onenand_chip *this = mtd->priv;
 136         struct bbm_info *bbm = this->bbm;
 137         int block;
 138         uint8_t res;
 139
 140         /* Get block number * 2 */
 141         block = (int) (offs >> (bbm->bbt_erase_shift - 1));
 142         res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
 143
 144         DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
 145                 (unsigned int) offs, block >> 1, res);
 146
 147         switch ((int) res) {
 148         case 0x00:      return 0;
 149         case 0x01:      return 1;
 150         case 0x02:      return allowbbt ? 0 : 1;
 151         }
 152
 153         return 1;
 154 }
 155
 156 /**
 157  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
 158  * @param mtd           MTD device structure
 159  * @param bd            descriptor for the good/bad block search pattern
 160  *
 161  * The function checks, if a bad block table(s) is/are already
 162  * available. If not it scans the device for manufacturer
 163  * marked good / bad blocks and writes the bad block table(s) to
 164  * the selected place.
 165  *
 166  * The bad block table memory is allocated here. It must be freed
 167  * by calling the onenand_free_bbt function.
 168  *
 169  */
 170 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
 171 {
 172         struct onenand_chip *this = mtd->priv;
 173         struct bbm_info *bbm = this->bbm;
 174         int len, ret = 0;
 175
 176         len = mtd->size >> (this->erase_shift + 2);
 177         /* Allocate memory (2bit per block) */
 178         bbm->bbt = kmalloc(len, GFP_KERNEL);
 179         if (!bbm->bbt) {
 180                 printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
 181                 return -ENOMEM;
 182         }
 183         /* Clear the memory bad block table */
 184         memset(bbm->bbt, 0x00, len);
 185
 186         /* Set the bad block position */
 187         bbm->badblockpos = ONENAND_BADBLOCK_POS;
 188
 189         /* Set erase shift */
 190         bbm->bbt_erase_shift = this->erase_shift;
 191
 192         if (!bbm->isbad_bbt)
 193                 bbm->isbad_bbt = onenand_isbad_bbt;
 194
 195         /* Scan the device to build a memory based bad block table */
 196         if ((ret = onenand_memory_bbt(mtd, bd))) {
 197                 printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
 198                 kfree(bbm->bbt);
 199                 bbm->bbt = NULL;
 200         }
 201
 202         return ret;
 203 }
 204
 205 /*
 206  * Define some generic bad / good block scan pattern which are used
 207  * while scanning a device for factory marked good / bad blocks.
 208  */
 209 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
 210
 211 static struct nand_bbt_descr largepage_memorybased = {
 212         .options = 0,
 213         .offs = 0,
 214         .len = 2,
 215         .pattern = scan_ff_pattern,
 216 };
 217
 218 /**
 219  * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
 220  * @param mtd           MTD device structure
 221  *
 222  * This function selects the default bad block table
 223  * support for the device and calls the onenand_scan_bbt function
 224  */
 225 int onenand_default_bbt(struct mtd_info *mtd)
 226 {
 227         struct onenand_chip *this = mtd->priv;
 228         struct bbm_info *bbm;
 229
 230         this->bbm = kmalloc(sizeof(struct bbm_info), GFP_KERNEL);
 231         if (!this->bbm)
 232                 return -ENOMEM;
 233
 234         bbm = this->bbm;
 235
 236         memset(bbm, 0, sizeof(struct bbm_info));
 237
 238         /* 1KB page has same configuration as 2KB page */
 239         if (!bbm->badblock_pattern)
 240                 bbm->badblock_pattern = &largepage_memorybased;
 241
 242         return onenand_scan_bbt(mtd, bbm->badblock_pattern);
 243 }
 244
 245 EXPORT_SYMBOL(onenand_scan_bbt);
 246 EXPORT_SYMBOL(onenand_default_bbt);