drivers/mtd/ssfdc.c

   1 /*
   2  * Linux driver for SSFDC Flash Translation Layer (Read only)
   3  * © 2005 Eptar srl
   4  * Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
   5  *
   6  * Based on NTFL and MTDBLOCK_RO drivers
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/slab.h>
  17 #include <linux/hdreg.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/mtd/nand.h>
  20 #include <linux/mtd/blktrans.h>
  21
  22 struct ssfdcr_record {
  23         struct mtd_blktrans_dev mbd;
  24         int usecount;
  25         unsigned char heads;
  26         unsigned char sectors;
  27         unsigned short cylinders;
  28         int cis_block;                  /* block n. containing CIS/IDI */
  29         int erase_size;                 /* phys_block_size */
  30         unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
  31                                             the 128MiB) */
  32         int map_len;                    /* n. phys_blocks on the card */
  33 };
  34
  35 #define SSFDCR_MAJOR            257
  36 #define SSFDCR_PARTN_BITS       3
  37
  38 #define SECTOR_SIZE             512
  39 #define SECTOR_SHIFT            9
  40 #define OOB_SIZE                16
  41
  42 #define MAX_LOGIC_BLK_PER_ZONE  1000
  43 #define MAX_PHYS_BLK_PER_ZONE   1024
  44
  45 #define KiB(x)  ( (x) * 1024L )
  46 #define MiB(x)  ( KiB(x) * 1024L )
  47
  48 /** CHS Table
  49                 1MiB    2MiB    4MiB    8MiB    16MiB   32MiB   64MiB   128MiB
  50 NCylinder       125     125     250     250     500     500     500     500
  51 NHead           4       4       4       4       4       8       8       16
  52 NSector         4       8       8       16      16      16      32      32
  53 SumSector       2,000   4,000   8,000   16,000  32,000  64,000  128,000 256,000
  54 SectorSize      512     512     512     512     512     512     512     512
  55 **/
  56
  57 typedef struct {
  58         unsigned long size;
  59         unsigned short cyl;
  60         unsigned char head;
  61         unsigned char sec;
  62 } chs_entry_t;
  63
  64 /* Must be ordered by size */
  65 static const chs_entry_t chs_table[] = {
  66         { MiB(  1), 125,  4,  4 },
  67         { MiB(  2), 125,  4,  8 },
  68         { MiB(  4), 250,  4,  8 },
  69         { MiB(  8), 250,  4, 16 },
  70         { MiB( 16), 500,  4, 16 },
  71         { MiB( 32), 500,  8, 16 },
  72         { MiB( 64), 500,  8, 32 },
  73         { MiB(128), 500, 16, 32 },
  74         { 0 },
  75 };
  76
  77 static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
  78                         unsigned char *sec)
  79 {
  80         int k;
  81         int found = 0;
  82
  83         k = 0;
  84         while (chs_table[k].size > 0 && size > chs_table[k].size)
  85                 k++;
  86
  87         if (chs_table[k].size > 0) {
  88                 if (cyl)
  89                         *cyl = chs_table[k].cyl;
  90                 if (head)
  91                         *head = chs_table[k].head;
  92                 if (sec)
  93                         *sec = chs_table[k].sec;
  94                 found = 1;
  95         }
  96
  97         return found;
  98 }
  99
 100 /* These bytes are the signature for the CIS/IDI sector */
 101 static const uint8_t cis_numbers[] = {
 102         0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
 103 };
 104
 105 /* Read and check for a valid CIS sector */
 106 static int get_valid_cis_sector(struct mtd_info *mtd)
 107 {
 108         int ret, k, cis_sector;
 109         size_t retlen;
 110         loff_t offset;
 111         uint8_t *sect_buf;
 112
 113         cis_sector = -1;
 114
 115         sect_buf = kmalloc(SECTOR_SIZE, GFP_KERNEL);
 116         if (!sect_buf)
 117                 goto out;
 118
 119         /*
 120          * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
 121          * blocks). If the first good block doesn't contain CIS number the flash
 122          * is not SSFDC formatted
 123          */
 124         for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
 125                 if (mtd_block_isbad(mtd, offset)) {
 126                         ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen,
 127                                        sect_buf);
 128
 129                         /* CIS pattern match on the sector buffer */
 130                         if (ret < 0 || retlen != SECTOR_SIZE) {
 131                                 printk(KERN_WARNING
 132                                         "SSFDC_RO:can't read CIS/IDI sector\n");
 133                         } else if (!memcmp(sect_buf, cis_numbers,
 134                                         sizeof(cis_numbers))) {
 135                                 /* Found */
 136                                 cis_sector = (int)(offset >> SECTOR_SHIFT);
 137                         } else {
 138                                 pr_debug("SSFDC_RO: CIS/IDI sector not found"
 139                                         " on %s (mtd%d)\n", mtd->name,
 140                                         mtd->index);
 141                         }
 142                         break;
 143                 }
 144         }
 145
 146         kfree(sect_buf);
 147  out:
 148         return cis_sector;
 149 }
 150
 151 /* Read physical sector (wrapper to MTD_READ) */
 152 static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
 153                                 int sect_no)
 154 {
 155         int ret;
 156         size_t retlen;
 157         loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;
 158
 159         ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
 160         if (ret < 0 || retlen != SECTOR_SIZE)
 161                 return -1;
 162
 163         return 0;
 164 }
 165
 166 /* Read redundancy area (wrapper to MTD_READ_OOB */
 167 static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
 168 {
 169         struct mtd_oob_ops ops;
 170         int ret;
 171
 172         ops.mode = MTD_OPS_RAW;
 173         ops.ooboffs = 0;
 174         ops.ooblen = OOB_SIZE;
 175         ops.oobbuf = buf;
 176         ops.datbuf = NULL;
 177
 178         ret = mtd_read_oob(mtd, offs, &ops);
 179         if (ret < 0 || ops.oobretlen != OOB_SIZE)
 180                 return -1;
 181
 182         return 0;
 183 }
 184
 185 /* Parity calculator on a word of n bit size */
 186 static int get_parity(int number, int size)
 187 {
 188         int k;
 189         int parity;
 190
 191         parity = 1;
 192         for (k = 0; k < size; k++) {
 193                 parity += (number >> k);
 194                 parity &= 1;
 195         }
 196         return parity;
 197 }
 198
 199 /* Read and validate the logical block address field stored in the OOB */
 200 static int get_logical_address(uint8_t *oob_buf)
 201 {
 202         int block_address, parity;
 203         int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
 204         int j;
 205         int ok = 0;
 206
 207         /*
 208          * Look for the first valid logical address
 209          * Valid address has fixed pattern on most significant bits and
 210          * parity check
 211          */
 212         for (j = 0; j < ARRAY_SIZE(offset); j++) {
 213                 block_address = ((int)oob_buf[offset[j]] << 8) |
 214                         oob_buf[offset[j]+1];
 215
 216                 /* Check for the signature bits in the address field (MSBits) */
 217                 if ((block_address & ~0x7FF) == 0x1000) {
 218                         parity = block_address & 0x01;
 219                         block_address &= 0x7FF;
 220                         block_address >>= 1;
 221
 222                         if (get_parity(block_address, 10) != parity) {
 223                                 pr_debug("SSFDC_RO: logical address field%d"
 224                                         "parity error(0x%04X)\n", j+1,
 225                                         block_address);
 226                         } else {
 227                                 ok = 1;
 228                                 break;
 229                         }
 230                 }
 231         }
 232
 233         if (!ok)
 234                 block_address = -2;
 235
 236         pr_debug("SSFDC_RO: get_logical_address() %d\n",
 237                 block_address);
 238
 239         return block_address;
 240 }
 241
 242 /* Build the logic block map */
 243 static int build_logical_block_map(struct ssfdcr_record *ssfdc)
 244 {
 245         unsigned long offset;
 246         uint8_t oob_buf[OOB_SIZE];
 247         int ret, block_address, phys_block;
 248         struct mtd_info *mtd = ssfdc->mbd.mtd;
 249
 250         pr_debug("SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
 251               ssfdc->map_len,
 252               (unsigned long)ssfdc->map_len * ssfdc->erase_size / 1024);
 253
 254         /* Scan every physical block, skip CIS block */
 255         for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
 256                         phys_block++) {
 257                 offset = (unsigned long)phys_block * ssfdc->erase_size;
 258                 if (mtd_block_isbad(mtd, offset))
 259                         continue;       /* skip bad blocks */
 260
 261                 ret = read_raw_oob(mtd, offset, oob_buf);
 262                 if (ret < 0) {
 263                         pr_debug("SSFDC_RO: mtd read_oob() failed at %lu\n",
 264                                 offset);
 265                         return -1;
 266                 }
 267                 block_address = get_logical_address(oob_buf);
 268
 269                 /* Skip invalid addresses */
 270                 if (block_address >= 0 &&
 271                                 block_address < MAX_LOGIC_BLK_PER_ZONE) {
 272                         int zone_index;
 273
 274                         zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
 275                         block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
 276                         ssfdc->logic_block_map[block_address] =
 277                                 (unsigned short)phys_block;
 278
 279                         pr_debug("SSFDC_RO: build_block_map() phys_block=%d,"
 280                                 "logic_block_addr=%d, zone=%d\n",
 281                                 phys_block, block_address, zone_index);
 282                 }
 283         }
 284         return 0;
 285 }
 286
 287 static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 288 {
 289         struct ssfdcr_record *ssfdc;
 290         int cis_sector;
 291
 292         /* Check for small page NAND flash */
 293         if (!mtd_type_is_nand(mtd) || mtd->oobsize != OOB_SIZE ||
 294             mtd->size > UINT_MAX)
 295                 return;
 296
 297         /* Check for SSDFC format by reading CIS/IDI sector */
 298         cis_sector = get_valid_cis_sector(mtd);
 299         if (cis_sector == -1)
 300                 return;
 301
 302         ssfdc = kzalloc(sizeof(struct ssfdcr_record), GFP_KERNEL);
 303         if (!ssfdc)
 304                 return;
 305
 306         ssfdc->mbd.mtd = mtd;
 307         ssfdc->mbd.devnum = -1;
 308         ssfdc->mbd.tr = tr;
 309         ssfdc->mbd.readonly = 1;
 310
 311         ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
 312         ssfdc->erase_size = mtd->erasesize;
 313         ssfdc->map_len = (u32)mtd->size / mtd->erasesize;
 314
 315         pr_debug("SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
 316                 ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
 317                 DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));
 318
 319         /* Set geometry */
 320         ssfdc->heads = 16;
 321         ssfdc->sectors = 32;
 322         get_chs(mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
 323         ssfdc->cylinders = (unsigned short)(((u32)mtd->size >> SECTOR_SHIFT) /
 324                         ((long)ssfdc->sectors * (long)ssfdc->heads));
 325
 326         pr_debug("SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
 327                 ssfdc->cylinders, ssfdc->heads , ssfdc->sectors,
 328                 (long)ssfdc->cylinders * (long)ssfdc->heads *
 329                 (long)ssfdc->sectors);
 330
 331         ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
 332                                 (long)ssfdc->sectors;
 333
 334         /* Allocate logical block map */
 335         ssfdc->logic_block_map = kmalloc(sizeof(ssfdc->logic_block_map[0]) *
 336                                          ssfdc->map_len, GFP_KERNEL);
 337         if (!ssfdc->logic_block_map)
 338                 goto out_err;
 339         memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
 340                 ssfdc->map_len);
 341
 342         /* Build logical block map */
 343         if (build_logical_block_map(ssfdc) < 0)
 344                 goto out_err;
 345
 346         /* Register device + partitions */
 347         if (add_mtd_blktrans_dev(&ssfdc->mbd))
 348                 goto out_err;
 349
 350         printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
 351                 ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
 352         return;
 353
 354 out_err:
 355         kfree(ssfdc->logic_block_map);
 356         kfree(ssfdc);
 357 }
 358
 359 static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
 360 {
 361         struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 362
 363         pr_debug("SSFDC_RO: remove_dev (i=%d)\n", dev->devnum);
 364
 365         del_mtd_blktrans_dev(dev);
 366         kfree(ssfdc->logic_block_map);
 367 }
 368
 369 static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,
 370                                 unsigned long logic_sect_no, char *buf)
 371 {
 372         struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 373         int sectors_per_block, offset, block_address;
 374
 375         sectors_per_block = ssfdc->erase_size >> SECTOR_SHIFT;
 376         offset = (int)(logic_sect_no % sectors_per_block);
 377         block_address = (int)(logic_sect_no / sectors_per_block);
 378
 379         pr_debug("SSFDC_RO: ssfdcr_readsect(%lu) sec_per_blk=%d, ofst=%d,"
 380                 " block_addr=%d\n", logic_sect_no, sectors_per_block, offset,
 381                 block_address);
 382
 383         if (block_address >= ssfdc->map_len)
 384                 BUG();
 385
 386         block_address = ssfdc->logic_block_map[block_address];
 387
 388         pr_debug("SSFDC_RO: ssfdcr_readsect() phys_block_addr=%d\n",
 389                 block_address);
 390
 391         if (block_address < 0xffff) {
 392                 unsigned long sect_no;
 393
 394                 sect_no = (unsigned long)block_address * sectors_per_block +
 395                                 offset;
 396
 397                 pr_debug("SSFDC_RO: ssfdcr_readsect() phys_sect_no=%lu\n",
 398                         sect_no);
 399
 400                 if (read_physical_sector(ssfdc->mbd.mtd, buf, sect_no) < 0)
 401                         return -EIO;
 402         } else {
 403                 memset(buf, 0xff, SECTOR_SIZE);
 404         }
 405
 406         return 0;
 407 }
 408
 409 static int ssfdcr_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
 410 {
 411         struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 412
 413         pr_debug("SSFDC_RO: ssfdcr_getgeo() C=%d, H=%d, S=%d\n",
 414                         ssfdc->cylinders, ssfdc->heads, ssfdc->sectors);
 415
 416         geo->heads = ssfdc->heads;
 417         geo->sectors = ssfdc->sectors;
 418         geo->cylinders = ssfdc->cylinders;
 419
 420         return 0;
 421 }
 422
 423 /****************************************************************************
 424  *
 425  * Module stuff
 426  *
 427  ****************************************************************************/
 428
 429 static struct mtd_blktrans_ops ssfdcr_tr = {
 430         .name           = "ssfdc",
 431         .major          = SSFDCR_MAJOR,
 432         .part_bits      = SSFDCR_PARTN_BITS,
 433         .blksize        = SECTOR_SIZE,
 434         .getgeo         = ssfdcr_getgeo,
 435         .readsect       = ssfdcr_readsect,
 436         .add_mtd        = ssfdcr_add_mtd,
 437         .remove_dev     = ssfdcr_remove_dev,
 438         .owner          = THIS_MODULE,
 439 };
 440
 441 static int __init init_ssfdcr(void)
 442 {
 443         printk(KERN_INFO "SSFDC read-only Flash Translation layer\n");
 444
 445         return register_mtd_blktrans(&ssfdcr_tr);
 446 }
 447
 448 static void __exit cleanup_ssfdcr(void)
 449 {
 450         deregister_mtd_blktrans(&ssfdcr_tr);
 451 }
 452
 453 module_init(init_ssfdcr);
 454 module_exit(cleanup_ssfdcr);
 455
 456 MODULE_LICENSE("GPL");
 457 MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
 458 MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");