linux/drivers/mtd/ssfdc.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Linux driver for SSFDC Flash Translation Layer (Read only)
   4 * \xC2\xA9 2005 Eptar srl
   5 * Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
   6 *
   7 * Based on NTFL and MTDBLOCK_RO drivers
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/module.h>
  12#include <linux/init.h>
  13#include <linux/slab.h>
  14#include <linux/hdreg.h>
  15#include <linux/mtd/mtd.h>
  16#include <linux/mtd/rawnand.h>
  17#include <linux/mtd/blktrans.h>
  18
  19struct ssfdcr_record {
  20        struct mtd_blktrans_dev mbd;
  21        int usecount;
  22        unsigned char heads;
  23        unsigned char sectors;
  24        unsigned short cylinders;
  25        int cis_block;                  /* block n. containing CIS/IDI */
  26        int erase_size;                 /* phys_block_size */
  27        unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
  28                                            the 128MiB) */
  29        int map_len;                    /* n. phys_blocks on the card */
  30};
  31
  32#define SSFDCR_MAJOR            257
  33#define SSFDCR_PARTN_BITS       3
  34
  35#define SECTOR_SIZE             512
  36#define SECTOR_SHIFT            9
  37#define OOB_SIZE                16
  38
  39#define MAX_LOGIC_BLK_PER_ZONE  1000
  40#define MAX_PHYS_BLK_PER_ZONE   1024
  41
  42#define KiB(x)  ( (x) * 1024L )
  43#define MiB(x)  ( KiB(x) * 1024L )
  44
  45/** CHS Table
  46                1MiB    2MiB    4MiB    8MiB    16MiB   32MiB   64MiB   128MiB
  47NCylinder       125     125     250     250     500     500     500     500
  48NHead           4       4       4       4       4       8       8       16
  49NSector         4       8       8       16      16      16      32      32
  50SumSector       2,000   4,000   8,000   16,000  32,000  64,000  128,000 256,000
  51SectorSize      512     512     512     512     512     512     512     512
  52**/
  53
  54typedef struct {
  55        unsigned long size;
  56        unsigned short cyl;
  57        unsigned char head;
  58        unsigned char sec;
  59} chs_entry_t;
  60
  61/* Must be ordered by size */
  62static const chs_entry_t chs_table[] = {
  63        { MiB(  1), 125,  4,  4 },
  64        { MiB(  2), 125,  4,  8 },
  65        { MiB(  4), 250,  4,  8 },
  66        { MiB(  8), 250,  4, 16 },
  67        { MiB( 16), 500,  4, 16 },
  68        { MiB( 32), 500,  8, 16 },
  69        { MiB( 64), 500,  8, 32 },
  70        { MiB(128), 500, 16, 32 },
  71        { 0 },
  72};
  73
  74static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
  75                        unsigned char *sec)
  76{
  77        int k;
  78        int found = 0;
  79
  80        k = 0;
  81        while (chs_table[k].size > 0 && size > chs_table[k].size)
  82                k++;
  83
  84        if (chs_table[k].size > 0) {
  85                if (cyl)
  86                        *cyl = chs_table[k].cyl;
  87                if (head)
  88                        *head = chs_table[k].head;
  89                if (sec)
  90                        *sec = chs_table[k].sec;
  91                found = 1;
  92        }
  93
  94        return found;
  95}
  96
  97/* These bytes are the signature for the CIS/IDI sector */
  98static const uint8_t cis_numbers[] = {
  99        0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
 100};
 101
 102/* Read and check for a valid CIS sector */
 103static int get_valid_cis_sector(struct mtd_info *mtd)
 104{
 105        int ret, k, cis_sector;
 106        size_t retlen;
 107        loff_t offset;
 108        uint8_t *sect_buf;
 109
 110        cis_sector = -1;
 111
 112        sect_buf = kmalloc(SECTOR_SIZE, GFP_KERNEL);
 113        if (!sect_buf)
 114                goto out;
 115
 116        /*
 117         * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
 118         * blocks). If the first good block doesn't contain CIS number the flash
 119         * is not SSFDC formatted
 120         */
 121        for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
 122                if (mtd_block_isbad(mtd, offset)) {
 123                        ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen,
 124                                       sect_buf);
 125
 126                        /* CIS pattern match on the sector buffer */
 127                        if (ret < 0 || retlen != SECTOR_SIZE) {
 128                                printk(KERN_WARNING
 129                                        "SSFDC_RO:can't read CIS/IDI sector\n");
 130                        } else if (!memcmp(sect_buf, cis_numbers,
 131                                        sizeof(cis_numbers))) {
 132                                /* Found */
 133                                cis_sector = (int)(offset >> SECTOR_SHIFT);
 134                        } else {
 135                                pr_debug("SSFDC_RO: CIS/IDI sector not found"
 136                                        " on %s (mtd%d)\n", mtd->name,
 137                                        mtd->index);
 138                        }
 139                        break;
 140                }
 141        }
 142
 143        kfree(sect_buf);
 144 out:
 145        return cis_sector;
 146}
 147
 148/* Read physical sector (wrapper to MTD_READ) */
 149static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
 150                                int sect_no)
 151{
 152        int ret;
 153        size_t retlen;
 154        loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;
 155
 156        ret = mtd_read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
 157        if (ret < 0 || retlen != SECTOR_SIZE)
 158                return -1;
 159
 160        return 0;
 161}
 162
 163/* Read redundancy area (wrapper to MTD_READ_OOB */
 164static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
 165{
 166        struct mtd_oob_ops ops;
 167        int ret;
 168
 169        ops.mode = MTD_OPS_RAW;
 170        ops.ooboffs = 0;
 171        ops.ooblen = OOB_SIZE;
 172        ops.oobbuf = buf;
 173        ops.datbuf = NULL;
 174
 175        ret = mtd_read_oob(mtd, offs, &ops);
 176        if (ret < 0 || ops.oobretlen != OOB_SIZE)
 177                return -1;
 178
 179        return 0;
 180}
 181
 182/* Parity calculator on a word of n bit size */
 183static int get_parity(int number, int size)
 184{
 185        int k;
 186        int parity;
 187
 188        parity = 1;
 189        for (k = 0; k < size; k++) {
 190                parity += (number >> k);
 191                parity &= 1;
 192        }
 193        return parity;
 194}
 195
 196/* Read and validate the logical block address field stored in the OOB */
 197static int get_logical_address(uint8_t *oob_buf)
 198{
 199        int block_address, parity;
 200        int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
 201        int j;
 202        int ok = 0;
 203
 204        /*
 205         * Look for the first valid logical address
 206         * Valid address has fixed pattern on most significant bits and
 207         * parity check
 208         */
 209        for (j = 0; j < ARRAY_SIZE(offset); j++) {
 210                block_address = ((int)oob_buf[offset[j]] << 8) |
 211                        oob_buf[offset[j]+1];
 212
 213                /* Check for the signature bits in the address field (MSBits) */
 214                if ((block_address & ~0x7FF) == 0x1000) {
 215                        parity = block_address & 0x01;
 216                        block_address &= 0x7FF;
 217                        block_address >>= 1;
 218
 219                        if (get_parity(block_address, 10) != parity) {
 220                                pr_debug("SSFDC_RO: logical address field%d"
 221                                        "parity error(0x%04X)\n", j+1,
 222                                        block_address);
 223                        } else {
 224                                ok = 1;
 225                                break;
 226                        }
 227                }
 228        }
 229
 230        if (!ok)
 231                block_address = -2;
 232
 233        pr_debug("SSFDC_RO: get_logical_address() %d\n",
 234                block_address);
 235
 236        return block_address;
 237}
 238
 239/* Build the logic block map */
 240static int build_logical_block_map(struct ssfdcr_record *ssfdc)
 241{
 242        unsigned long offset;
 243        uint8_t oob_buf[OOB_SIZE];
 244        int ret, block_address, phys_block;
 245        struct mtd_info *mtd = ssfdc->mbd.mtd;
 246
 247        pr_debug("SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
 248              ssfdc->map_len,
 249              (unsigned long)ssfdc->map_len * ssfdc->erase_size / 1024);
 250
 251        /* Scan every physical block, skip CIS block */
 252        for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
 253                        phys_block++) {
 254                offset = (unsigned long)phys_block * ssfdc->erase_size;
 255                if (mtd_block_isbad(mtd, offset))
 256                        continue;       /* skip bad blocks */
 257
 258                ret = read_raw_oob(mtd, offset, oob_buf);
 259                if (ret < 0) {
 260                        pr_debug("SSFDC_RO: mtd read_oob() failed at %lu\n",
 261                                offset);
 262                        return -1;
 263                }
 264                block_address = get_logical_address(oob_buf);
 265
 266                /* Skip invalid addresses */
 267                if (block_address >= 0 &&
 268                                block_address < MAX_LOGIC_BLK_PER_ZONE) {
 269                        int zone_index;
 270
 271                        zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
 272                        block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
 273                        ssfdc->logic_block_map[block_address] =
 274                                (unsigned short)phys_block;
 275
 276                        pr_debug("SSFDC_RO: build_block_map() phys_block=%d,"
 277                                "logic_block_addr=%d, zone=%d\n",
 278                                phys_block, block_address, zone_index);
 279                }
 280        }
 281        return 0;
 282}
 283
 284static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 285{
 286        struct ssfdcr_record *ssfdc;
 287        int cis_sector;
 288
 289        /* Check for small page NAND flash */
 290        if (!mtd_type_is_nand(mtd) || mtd->oobsize != OOB_SIZE ||
 291            mtd->size > UINT_MAX)
 292                return;
 293
 294        /* Check for SSDFC format by reading CIS/IDI sector */
 295        cis_sector = get_valid_cis_sector(mtd);
 296        if (cis_sector == -1)
 297                return;
 298
 299        ssfdc = kzalloc(sizeof(struct ssfdcr_record), GFP_KERNEL);
 300        if (!ssfdc)
 301                return;
 302
 303        ssfdc->mbd.mtd = mtd;
 304        ssfdc->mbd.devnum = -1;
 305        ssfdc->mbd.tr = tr;
 306        ssfdc->mbd.readonly = 1;
 307
 308        ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
 309        ssfdc->erase_size = mtd->erasesize;
 310        ssfdc->map_len = (u32)mtd->size / mtd->erasesize;
 311
 312        pr_debug("SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
 313                ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
 314                DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));
 315
 316        /* Set geometry */
 317        ssfdc->heads = 16;
 318        ssfdc->sectors = 32;
 319        get_chs(mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
 320        ssfdc->cylinders = (unsigned short)(((u32)mtd->size >> SECTOR_SHIFT) /
 321                        ((long)ssfdc->sectors * (long)ssfdc->heads));
 322
 323        pr_debug("SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
 324                ssfdc->cylinders, ssfdc->heads , ssfdc->sectors,
 325                (long)ssfdc->cylinders * (long)ssfdc->heads *
 326                (long)ssfdc->sectors);
 327
 328        ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
 329                                (long)ssfdc->sectors;
 330
 331        /* Allocate logical block map */
 332        ssfdc->logic_block_map =
 333                kmalloc_array(ssfdc->map_len,
 334                              sizeof(ssfdc->logic_block_map[0]), GFP_KERNEL);
 335        if (!ssfdc->logic_block_map)
 336                goto out_err;
 337        memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
 338                ssfdc->map_len);
 339
 340        /* Build logical block map */
 341        if (build_logical_block_map(ssfdc) < 0)
 342                goto out_err;
 343
 344        /* Register device + partitions */
 345        if (add_mtd_blktrans_dev(&ssfdc->mbd))
 346                goto out_err;
 347
 348        printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
 349                ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
 350        return;
 351
 352out_err:
 353        kfree(ssfdc->logic_block_map);
 354        kfree(ssfdc);
 355}
 356
 357static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
 358{
 359        struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 360
 361        pr_debug("SSFDC_RO: remove_dev (i=%d)\n", dev->devnum);
 362
 363        del_mtd_blktrans_dev(dev);
 364        kfree(ssfdc->logic_block_map);
 365}
 366
 367static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,
 368                                unsigned long logic_sect_no, char *buf)
 369{
 370        struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 371        int sectors_per_block, offset, block_address;
 372
 373        sectors_per_block = ssfdc->erase_size >> SECTOR_SHIFT;
 374        offset = (int)(logic_sect_no % sectors_per_block);
 375        block_address = (int)(logic_sect_no / sectors_per_block);
 376
 377        pr_debug("SSFDC_RO: ssfdcr_readsect(%lu) sec_per_blk=%d, ofst=%d,"
 378                " block_addr=%d\n", logic_sect_no, sectors_per_block, offset,
 379                block_address);
 380
 381        BUG_ON(block_address >= ssfdc->map_len);
 382
 383        block_address = ssfdc->logic_block_map[block_address];
 384
 385        pr_debug("SSFDC_RO: ssfdcr_readsect() phys_block_addr=%d\n",
 386                block_address);
 387
 388        if (block_address < 0xffff) {
 389                unsigned long sect_no;
 390
 391                sect_no = (unsigned long)block_address * sectors_per_block +
 392                                offset;
 393
 394                pr_debug("SSFDC_RO: ssfdcr_readsect() phys_sect_no=%lu\n",
 395                        sect_no);
 396
 397                if (read_physical_sector(ssfdc->mbd.mtd, buf, sect_no) < 0)
 398                        return -EIO;
 399        } else {
 400                memset(buf, 0xff, SECTOR_SIZE);
 401        }
 402
 403        return 0;
 404}
 405
 406static int ssfdcr_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
 407{
 408        struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
 409
 410        pr_debug("SSFDC_RO: ssfdcr_getgeo() C=%d, H=%d, S=%d\n",
 411                        ssfdc->cylinders, ssfdc->heads, ssfdc->sectors);
 412
 413        geo->heads = ssfdc->heads;
 414        geo->sectors = ssfdc->sectors;
 415        geo->cylinders = ssfdc->cylinders;
 416
 417        return 0;
 418}
 419
 420/****************************************************************************
 421 *
 422 * Module stuff
 423 *
 424 ****************************************************************************/
 425
 426static struct mtd_blktrans_ops ssfdcr_tr = {
 427        .name           = "ssfdc",
 428        .major          = SSFDCR_MAJOR,
 429        .part_bits      = SSFDCR_PARTN_BITS,
 430        .blksize        = SECTOR_SIZE,
 431        .getgeo         = ssfdcr_getgeo,
 432        .readsect       = ssfdcr_readsect,
 433        .add_mtd        = ssfdcr_add_mtd,
 434        .remove_dev     = ssfdcr_remove_dev,
 435        .owner          = THIS_MODULE,
 436};
 437
 438static int __init init_ssfdcr(void)
 439{
 440        printk(KERN_INFO "SSFDC read-only Flash Translation layer\n");
 441
 442        return register_mtd_blktrans(&ssfdcr_tr);
 443}
 444
 445static void __exit cleanup_ssfdcr(void)
 446{
 447        deregister_mtd_blktrans(&ssfdcr_tr);
 448}
 449
 450module_init(init_ssfdcr);
 451module_exit(cleanup_ssfdcr);
 452
 453MODULE_LICENSE("GPL");
 454MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
 455MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");
 456