linux/drivers/mtd/ssfdc.c
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   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
  22struct 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
  50NCylinder       125     125     250     250     500     500     500     500
  51NHead           4       4       4       4       4       8       8       16
  52NSector         4       8       8       16      16      16      32      32
  53SumSector       2,000   4,000   8,000   16,000  32,000  64,000  128,000 256,000
  54SectorSize      512     512     512     512     512     512     512     512
  55**/
  56
  57typedef 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 */
  65static 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
  77static 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 */
 101static 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 */
 106static 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) */
 152static 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 */
 167static 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 */
 186static 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 */
 200static 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 */
 243static 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
 287static 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 != MTD_NANDFLASH || 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
 354out_err:
 355        kfree(ssfdc->logic_block_map);
 356        kfree(ssfdc);
 357}
 358
 359static 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
 369static 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
 409static 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
 429static 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
 441static 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
 448static void __exit cleanup_ssfdcr(void)
 449{
 450        deregister_mtd_blktrans(&ssfdcr_tr);
 451}
 452
 453module_init(init_ssfdcr);
 454module_exit(cleanup_ssfdcr);
 455
 456MODULE_LICENSE("GPL");
 457MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
 458MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");
 459
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