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