release/src-rt-6.x/linux/linux-2.6/drivers/mtd/devices/mtd_dataflash.c

   1 /*
   2  * Atmel AT45xxx DataFlash MTD driver for lightweight SPI framework
   3  *
   4  * Largely derived from at91_dataflash.c:
   5  *  Copyright (C) 2003-2005 SAN People (Pty) Ltd
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11 */
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/delay.h>
  16 #include <linux/device.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/spi/flash.h>
  19
  20 #include <linux/mtd/mtd.h>
  21 #include <linux/mtd/partitions.h>
  22
  23
  24 /*
  25  * DataFlash is a kind of SPI flash.  Most AT45 chips have two buffers in
  26  * each chip, which may be used for double buffered I/O; but this driver
  27  * doesn't (yet) use these for any kind of i/o overlap or prefetching.
  28  *
  29  * Sometimes DataFlash is packaged in MMC-format cards, although the
  30  * MMC stack can't use SPI (yet), or distinguish between MMC and DataFlash
  31  * protocols during enumeration.
  32  */
  33
  34 #define CONFIG_DATAFLASH_WRITE_VERIFY
  35
  36 /* reads can bypass the buffers */
  37 #define OP_READ_CONTINUOUS      0xE8
  38 #define OP_READ_PAGE            0xD2
  39
  40 /* group B requests can run even while status reports "busy" */
  41 #define OP_READ_STATUS          0xD7    /* group B */
  42
  43 /* move data between host and buffer */
  44 #define OP_READ_BUFFER1         0xD4    /* group B */
  45 #define OP_READ_BUFFER2         0xD6    /* group B */
  46 #define OP_WRITE_BUFFER1        0x84    /* group B */
  47 #define OP_WRITE_BUFFER2        0x87    /* group B */
  48
  49 /* erasing flash */
  50 #define OP_ERASE_PAGE           0x81
  51 #define OP_ERASE_BLOCK          0x50
  52
  53 /* move data between buffer and flash */
  54 #define OP_TRANSFER_BUF1        0x53
  55 #define OP_TRANSFER_BUF2        0x55
  56 #define OP_MREAD_BUFFER1        0xD4
  57 #define OP_MREAD_BUFFER2        0xD6
  58 #define OP_MWERASE_BUFFER1      0x83
  59 #define OP_MWERASE_BUFFER2      0x86
  60 #define OP_MWRITE_BUFFER1       0x88    /* sector must be pre-erased */
  61 #define OP_MWRITE_BUFFER2       0x89    /* sector must be pre-erased */
  62
  63 /* write to buffer, then write-erase to flash */
  64 #define OP_PROGRAM_VIA_BUF1     0x82
  65 #define OP_PROGRAM_VIA_BUF2     0x85
  66
  67 /* compare buffer to flash */
  68 #define OP_COMPARE_BUF1         0x60
  69 #define OP_COMPARE_BUF2         0x61
  70
  71 /* read flash to buffer, then write-erase to flash */
  72 #define OP_REWRITE_VIA_BUF1     0x58
  73 #define OP_REWRITE_VIA_BUF2     0x59
  74
  75 /* newer chips report JEDEC manufacturer and device IDs; chip
  76  * serial number and OTP bits; and per-sector writeprotect.
  77  */
  78 #define OP_READ_ID              0x9F
  79 #define OP_READ_SECURITY        0x77
  80 #define OP_WRITE_SECURITY       0x9A    /* OTP bits */
  81
  82
  83 struct dataflash {
  84         u8                      command[4];
  85         char                    name[24];
  86
  87         unsigned                partitioned:1;
  88
  89         unsigned short          page_offset;    /* offset in flash address */
  90         unsigned int            page_size;      /* of bytes per page */
  91
  92         struct semaphore        lock;
  93         struct spi_device       *spi;
  94
  95         struct mtd_info         mtd;
  96 };
  97
  98 #ifdef CONFIG_MTD_PARTITIONS
  99 #define mtd_has_partitions()    (1)
 100 #else
 101 #define mtd_has_partitions()    (0)
 102 #endif
 103
 104 /* ......................................................................... */
 105
 106 /*
 107  * Return the status of the DataFlash device.
 108  */
 109 static inline int dataflash_status(struct spi_device *spi)
 110 {
 111         /* NOTE:  at45db321c over 25 MHz wants to write
 112          * a dummy byte after the opcode...
 113          */
 114         return spi_w8r8(spi, OP_READ_STATUS);
 115 }
 116
 117 /*
 118  * Poll the DataFlash device until it is READY.
 119  * This usually takes 5-20 msec or so; more for sector erase.
 120  */
 121 static int dataflash_waitready(struct spi_device *spi)
 122 {
 123         int     status;
 124
 125         for (;;) {
 126                 status = dataflash_status(spi);
 127                 if (status < 0) {
 128                         DEBUG(MTD_DEBUG_LEVEL1, "%s: status %d?\n",
 129                                         spi->dev.bus_id, status);
 130                         status = 0;
 131                 }
 132
 133                 if (status & (1 << 7))  /* RDY/nBSY */
 134                         return status;
 135
 136                 msleep(3);
 137         }
 138 }
 139
 140 /* ......................................................................... */
 141
 142 /*
 143  * Erase pages of flash.
 144  */
 145 static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
 146 {
 147         struct dataflash        *priv = (struct dataflash *)mtd->priv;
 148         struct spi_device       *spi = priv->spi;
 149         struct spi_transfer     x = { .tx_dma = 0, };
 150         struct spi_message      msg;
 151         unsigned                blocksize = priv->page_size << 3;
 152         u8                      *command;
 153
 154         DEBUG(MTD_DEBUG_LEVEL2, "%s: erase addr=0x%x len 0x%x\n",
 155                         spi->dev.bus_id,
 156                         instr->addr, instr->len);
 157
 158         /* Sanity checks */
 159         if ((instr->addr + instr->len) > mtd->size
 160                         || (instr->len % priv->page_size) != 0
 161                         || (instr->addr % priv->page_size) != 0)
 162                 return -EINVAL;
 163
 164         spi_message_init(&msg);
 165
 166         x.tx_buf = command = priv->command;
 167         x.len = 4;
 168         spi_message_add_tail(&x, &msg);
 169
 170         down(&priv->lock);
 171         while (instr->len > 0) {
 172                 unsigned int    pageaddr;
 173                 int             status;
 174                 int             do_block;
 175
 176                 /* Calculate flash page address; use block erase (for speed) if
 177                  * we're at a block boundary and need to erase the whole block.
 178                  */
 179                 pageaddr = instr->addr / priv->page_size;
 180                 do_block = (pageaddr & 0x7) == 0 && instr->len >= blocksize;
 181                 pageaddr = pageaddr << priv->page_offset;
 182
 183                 command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;
 184                 command[1] = (u8)(pageaddr >> 16);
 185                 command[2] = (u8)(pageaddr >> 8);
 186                 command[3] = 0;
 187
 188                 DEBUG(MTD_DEBUG_LEVEL3, "ERASE %s: (%x) %x %x %x [%i]\n",
 189                         do_block ? "block" : "page",
 190                         command[0], command[1], command[2], command[3],
 191                         pageaddr);
 192
 193                 status = spi_sync(spi, &msg);
 194                 (void) dataflash_waitready(spi);
 195
 196                 if (status < 0) {
 197                         printk(KERN_ERR "%s: erase %x, err %d\n",
 198                                 spi->dev.bus_id, pageaddr, status);
 199                         /* REVISIT:  can retry instr->retries times; or
 200                          * giveup and instr->fail_addr = instr->addr;
 201                          */
 202                         continue;
 203                 }
 204
 205                 if (do_block) {
 206                         instr->addr += blocksize;
 207                         instr->len -= blocksize;
 208                 } else {
 209                         instr->addr += priv->page_size;
 210                         instr->len -= priv->page_size;
 211                 }
 212         }
 213         up(&priv->lock);
 214
 215         /* Inform MTD subsystem that erase is complete */
 216         instr->state = MTD_ERASE_DONE;
 217         mtd_erase_callback(instr);
 218
 219         return 0;
 220 }
 221
 222 /*
 223  * Read from the DataFlash device.
 224  *   from   : Start offset in flash device
 225  *   len    : Amount to read
 226  *   retlen : About of data actually read
 227  *   buf    : Buffer containing the data
 228  */
 229 static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
 230                                size_t *retlen, u_char *buf)
 231 {
 232         struct dataflash        *priv = (struct dataflash *)mtd->priv;
 233         struct spi_transfer     x[2] = { { .tx_dma = 0, }, };
 234         struct spi_message      msg;
 235         unsigned int            addr;
 236         u8                      *command;
 237         int                     status;
 238
 239         DEBUG(MTD_DEBUG_LEVEL2, "%s: read 0x%x..0x%x\n",
 240                 priv->spi->dev.bus_id, (unsigned)from, (unsigned)(from + len));
 241
 242         *retlen = 0;
 243
 244         /* Sanity checks */
 245         if (!len)
 246                 return 0;
 247         if (from + len > mtd->size)
 248                 return -EINVAL;
 249
 250         /* Calculate flash page/byte address */
 251         addr = (((unsigned)from / priv->page_size) << priv->page_offset)
 252                 + ((unsigned)from % priv->page_size);
 253
 254         command = priv->command;
 255
 256         DEBUG(MTD_DEBUG_LEVEL3, "READ: (%x) %x %x %x\n",
 257                 command[0], command[1], command[2], command[3]);
 258
 259         spi_message_init(&msg);
 260
 261         x[0].tx_buf = command;
 262         x[0].len = 8;
 263         spi_message_add_tail(&x[0], &msg);
 264
 265         x[1].rx_buf = buf;
 266         x[1].len = len;
 267         spi_message_add_tail(&x[1], &msg);
 268
 269         down(&priv->lock);
 270
 271         /* Continuous read, max clock = f(car) which may be less than
 272          * the peak rate available.  Some chips support commands with
 273          * fewer "don't care" bytes.  Both buffers stay unchanged.
 274          */
 275         command[0] = OP_READ_CONTINUOUS;
 276         command[1] = (u8)(addr >> 16);
 277         command[2] = (u8)(addr >> 8);
 278         command[3] = (u8)(addr >> 0);
 279         /* plus 4 "don't care" bytes */
 280
 281         status = spi_sync(priv->spi, &msg);
 282         up(&priv->lock);
 283
 284         if (status >= 0) {
 285                 *retlen = msg.actual_length - 8;
 286                 status = 0;
 287         } else
 288                 DEBUG(MTD_DEBUG_LEVEL1, "%s: read %x..%x --> %d\n",
 289                         priv->spi->dev.bus_id,
 290                         (unsigned)from, (unsigned)(from + len),
 291                         status);
 292         return status;
 293 }
 294
 295 /*
 296  * Write to the DataFlash device.
 297  *   to     : Start offset in flash device
 298  *   len    : Amount to write
 299  *   retlen : Amount of data actually written
 300  *   buf    : Buffer containing the data
 301  */
 302 static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
 303                                 size_t * retlen, const u_char * buf)
 304 {
 305         struct dataflash        *priv = (struct dataflash *)mtd->priv;
 306         struct spi_device       *spi = priv->spi;
 307         struct spi_transfer     x[2] = { { .tx_dma = 0, }, };
 308         struct spi_message      msg;
 309         unsigned int            pageaddr, addr, offset, writelen;
 310         size_t                  remaining = len;
 311         u_char                  *writebuf = (u_char *) buf;
 312         int                     status = -EINVAL;
 313         u8                      *command;
 314
 315         DEBUG(MTD_DEBUG_LEVEL2, "%s: write 0x%x..0x%x\n",
 316                 spi->dev.bus_id, (unsigned)to, (unsigned)(to + len));
 317
 318         *retlen = 0;
 319
 320         /* Sanity checks */
 321         if (!len)
 322                 return 0;
 323         if ((to + len) > mtd->size)
 324                 return -EINVAL;
 325
 326         spi_message_init(&msg);
 327
 328         x[0].tx_buf = command = priv->command;
 329         x[0].len = 4;
 330         spi_message_add_tail(&x[0], &msg);
 331
 332         pageaddr = ((unsigned)to / priv->page_size);
 333         offset = ((unsigned)to % priv->page_size);
 334         if (offset + len > priv->page_size)
 335                 writelen = priv->page_size - offset;
 336         else
 337                 writelen = len;
 338
 339         down(&priv->lock);
 340         while (remaining > 0) {
 341                 DEBUG(MTD_DEBUG_LEVEL3, "write @ %i:%i len=%i\n",
 342                         pageaddr, offset, writelen);
 343
 344                 /* REVISIT:
 345                  * (a) each page in a sector must be rewritten at least
 346                  *     once every 10K sibling erase/program operations.
 347                  * (b) for pages that are already erased, we could
 348                  *     use WRITE+MWRITE not PROGRAM for ~30% speedup.
 349                  * (c) WRITE to buffer could be done while waiting for
 350                  *     a previous MWRITE/MWERASE to complete ...
 351                  * (d) error handling here seems to be mostly missing.
 352                  *
 353                  * Two persistent bits per page, plus a per-sector counter,
 354                  * could support (a) and (b) ... we might consider using
 355                  * the second half of sector zero, which is just one block,
 356                  * to track that state.  (On AT91, that sector should also
 357                  * support boot-from-DataFlash.)
 358                  */
 359
 360                 addr = pageaddr << priv->page_offset;
 361
 362                 /* (1) Maybe transfer partial page to Buffer1 */
 363                 if (writelen != priv->page_size) {
 364                         command[0] = OP_TRANSFER_BUF1;
 365                         command[1] = (addr & 0x00FF0000) >> 16;
 366                         command[2] = (addr & 0x0000FF00) >> 8;
 367                         command[3] = 0;
 368
 369                         DEBUG(MTD_DEBUG_LEVEL3, "TRANSFER: (%x) %x %x %x\n",
 370                                 command[0], command[1], command[2], command[3]);
 371
 372                         status = spi_sync(spi, &msg);
 373                         if (status < 0)
 374                                 DEBUG(MTD_DEBUG_LEVEL1, "%s: xfer %u -> %d \n",
 375                                         spi->dev.bus_id, addr, status);
 376
 377                         (void) dataflash_waitready(priv->spi);
 378                 }
 379
 380                 /* (2) Program full page via Buffer1 */
 381                 addr += offset;
 382                 command[0] = OP_PROGRAM_VIA_BUF1;
 383                 command[1] = (addr & 0x00FF0000) >> 16;
 384                 command[2] = (addr & 0x0000FF00) >> 8;
 385                 command[3] = (addr & 0x000000FF);
 386
 387                 DEBUG(MTD_DEBUG_LEVEL3, "PROGRAM: (%x) %x %x %x\n",
 388                         command[0], command[1], command[2], command[3]);
 389
 390                 x[1].tx_buf = writebuf;
 391                 x[1].len = writelen;
 392                 spi_message_add_tail(x + 1, &msg);
 393                 status = spi_sync(spi, &msg);
 394                 spi_transfer_del(x + 1);
 395                 if (status < 0)
 396                         DEBUG(MTD_DEBUG_LEVEL1, "%s: pgm %u/%u -> %d \n",
 397                                 spi->dev.bus_id, addr, writelen, status);
 398
 399                 (void) dataflash_waitready(priv->spi);
 400
 401
 402 #ifdef  CONFIG_DATAFLASH_WRITE_VERIFY
 403
 404                 /* (3) Compare to Buffer1 */
 405                 addr = pageaddr << priv->page_offset;
 406                 command[0] = OP_COMPARE_BUF1;
 407                 command[1] = (addr & 0x00FF0000) >> 16;
 408                 command[2] = (addr & 0x0000FF00) >> 8;
 409                 command[3] = 0;
 410
 411                 DEBUG(MTD_DEBUG_LEVEL3, "COMPARE: (%x) %x %x %x\n",
 412                         command[0], command[1], command[2], command[3]);
 413
 414                 status = spi_sync(spi, &msg);
 415                 if (status < 0)
 416                         DEBUG(MTD_DEBUG_LEVEL1, "%s: compare %u -> %d \n",
 417                                 spi->dev.bus_id, addr, status);
 418
 419                 status = dataflash_waitready(priv->spi);
 420
 421                 /* Check result of the compare operation */
 422                 if ((status & (1 << 6)) == 1) {
 423                         printk(KERN_ERR "%s: compare page %u, err %d\n",
 424                                 spi->dev.bus_id, pageaddr, status);
 425                         remaining = 0;
 426                         status = -EIO;
 427                         break;
 428                 } else
 429                         status = 0;
 430
 431 #endif  /* CONFIG_DATAFLASH_WRITE_VERIFY */
 432
 433                 remaining = remaining - writelen;
 434                 pageaddr++;
 435                 offset = 0;
 436                 writebuf += writelen;
 437                 *retlen += writelen;
 438
 439                 if (remaining > priv->page_size)
 440                         writelen = priv->page_size;
 441                 else
 442                         writelen = remaining;
 443         }
 444         up(&priv->lock);
 445
 446         return status;
 447 }
 448
 449 /* ......................................................................... */
 450
 451 /*
 452  * Register DataFlash device with MTD subsystem.
 453  */
 454 static int __devinit
 455 add_dataflash(struct spi_device *spi, char *name,
 456                 int nr_pages, int pagesize, int pageoffset)
 457 {
 458         struct dataflash                *priv;
 459         struct mtd_info                 *device;
 460         struct flash_platform_data      *pdata = spi->dev.platform_data;
 461
 462         priv = kzalloc(sizeof *priv, GFP_KERNEL);
 463         if (!priv)
 464                 return -ENOMEM;
 465
 466         init_MUTEX(&priv->lock);
 467         priv->spi = spi;
 468         priv->page_size = pagesize;
 469         priv->page_offset = pageoffset;
 470
 471         /* name must be usable with cmdlinepart */
 472         sprintf(priv->name, "spi%d.%d-%s",
 473                         spi->master->bus_num, spi->chip_select,
 474                         name);
 475
 476         device = &priv->mtd;
 477         device->name = (pdata && pdata->name) ? pdata->name : priv->name;
 478         device->size = nr_pages * pagesize;
 479         device->erasesize = pagesize;
 480         device->writesize = pagesize;
 481         device->owner = THIS_MODULE;
 482         device->type = MTD_DATAFLASH;
 483         device->flags = MTD_WRITEABLE;
 484         device->erase = dataflash_erase;
 485         device->read = dataflash_read;
 486         device->write = dataflash_write;
 487         device->priv = priv;
 488
 489         dev_info(&spi->dev, "%s (%d KBytes)\n", name, device->size/1024);
 490         dev_set_drvdata(&spi->dev, priv);
 491
 492         if (mtd_has_partitions()) {
 493                 struct mtd_partition    *parts;
 494                 int                     nr_parts = 0;
 495
 496 #ifdef CONFIG_MTD_CMDLINE_PARTS
 497                 static const char *part_probes[] = { "cmdlinepart", NULL, };
 498
 499                 nr_parts = parse_mtd_partitions(device, part_probes, &parts, 0);
 500 #endif
 501
 502                 if (nr_parts <= 0 && pdata && pdata->parts) {
 503                         parts = pdata->parts;
 504                         nr_parts = pdata->nr_parts;
 505                 }
 506
 507                 if (nr_parts > 0) {
 508                         priv->partitioned = 1;
 509                         return add_mtd_partitions(device, parts, nr_parts);
 510                 }
 511         } else if (pdata && pdata->nr_parts)
 512                 dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",
 513                                 pdata->nr_parts, device->name);
 514
 515         return add_mtd_device(device) == 1 ? -ENODEV : 0;
 516 }
 517
 518 /*
 519  * Detect and initialize DataFlash device:
 520  *
 521  *   Device      Density         ID code          #Pages PageSize  Offset
 522  *   AT45DB011B  1Mbit   (128K)  xx0011xx (0x0c)    512    264      9
 523  *   AT45DB021B  2Mbit   (256K)  xx0101xx (0x14)   1025    264      9
 524  *   AT45DB041B  4Mbit   (512K)  xx0111xx (0x1c)   2048    264      9
 525  *   AT45DB081B  8Mbit   (1M)    xx1001xx (0x24)   4096    264      9
 526  *   AT45DB0161B 16Mbit  (2M)    xx1011xx (0x2c)   4096    528     10
 527  *   AT45DB0321B 32Mbit  (4M)    xx1101xx (0x34)   8192    528     10
 528  *   AT45DB0642  64Mbit  (8M)    xx111xxx (0x3c)   8192   1056     11
 529  *   AT45DB1282  128Mbit (16M)   xx0100xx (0x10)  16384   1056     11
 530  */
 531 static int __devinit dataflash_probe(struct spi_device *spi)
 532 {
 533         int status;
 534
 535         status = dataflash_status(spi);
 536         if (status <= 0 || status == 0xff) {
 537                 DEBUG(MTD_DEBUG_LEVEL1, "%s: status error %d\n",
 538                                 spi->dev.bus_id, status);
 539                 if (status == 0 || status == 0xff)
 540                         status = -ENODEV;
 541                 return status;
 542         }
 543
 544         /* if there's a device there, assume it's dataflash.
 545          * board setup should have set spi->max_speed_max to
 546          * match f(car) for continuous reads, mode 0 or 3.
 547          */
 548         switch (status & 0x3c) {
 549         case 0x0c:      /* 0 0 1 1 x x */
 550                 status = add_dataflash(spi, "AT45DB011B", 512, 264, 9);
 551                 break;
 552         case 0x14:      /* 0 1 0 1 x x */
 553                 status = add_dataflash(spi, "AT45DB021B", 1025, 264, 9);
 554                 break;
 555         case 0x1c:      /* 0 1 1 1 x x */
 556                 status = add_dataflash(spi, "AT45DB041x", 2048, 264, 9);
 557                 break;
 558         case 0x24:      /* 1 0 0 1 x x */
 559                 status = add_dataflash(spi, "AT45DB081B", 4096, 264, 9);
 560                 break;
 561         case 0x2c:      /* 1 0 1 1 x x */
 562                 status = add_dataflash(spi, "AT45DB161x", 4096, 528, 10);
 563                 break;
 564         case 0x34:      /* 1 1 0 1 x x */
 565                 status = add_dataflash(spi, "AT45DB321x", 8192, 528, 10);
 566                 break;
 567         case 0x38:      /* 1 1 1 x x x */
 568         case 0x3c:
 569                 status = add_dataflash(spi, "AT45DB642x", 8192, 1056, 11);
 570                 break;
 571         /* obsolete AT45DB1282 not (yet?) supported */
 572         default:
 573                 DEBUG(MTD_DEBUG_LEVEL1, "%s: unsupported device (%x)\n",
 574                                 spi->dev.bus_id, status & 0x3c);
 575                 status = -ENODEV;
 576         }
 577
 578         if (status < 0)
 579                 DEBUG(MTD_DEBUG_LEVEL1, "%s: add_dataflash --> %d\n",
 580                                 spi->dev.bus_id, status);
 581
 582         return status;
 583 }
 584
 585 static int __devexit dataflash_remove(struct spi_device *spi)
 586 {
 587         struct dataflash        *flash = dev_get_drvdata(&spi->dev);
 588         int                     status;
 589
 590         DEBUG(MTD_DEBUG_LEVEL1, "%s: remove\n", spi->dev.bus_id);
 591
 592         if (mtd_has_partitions() && flash->partitioned)
 593                 status = del_mtd_partitions(&flash->mtd);
 594         else
 595                 status = del_mtd_device(&flash->mtd);
 596         if (status == 0)
 597                 kfree(flash);
 598         return status;
 599 }
 600
 601 static struct spi_driver dataflash_driver = {
 602         .driver = {
 603                 .name           = "mtd_dataflash",
 604                 .bus            = &spi_bus_type,
 605                 .owner          = THIS_MODULE,
 606         },
 607
 608         .probe          = dataflash_probe,
 609         .remove         = __devexit_p(dataflash_remove),
 610
 611         /* FIXME:  investigate suspend and resume... */
 612 };
 613
 614 static int __init dataflash_init(void)
 615 {
 616         return spi_register_driver(&dataflash_driver);
 617 }
 618 module_init(dataflash_init);
 619
 620 static void __exit dataflash_exit(void)
 621 {
 622         spi_unregister_driver(&dataflash_driver);
 623 }
 624 module_exit(dataflash_exit);
 625
 626
 627 MODULE_LICENSE("GPL");
 628 MODULE_AUTHOR("Andrew Victor, David Brownell");
 629 MODULE_DESCRIPTION("MTD DataFlash driver");