drivers/mmc/card/block.c

   1 /*
   2  * Block driver for media (i.e., flash cards)
   3  *
   4  * Copyright 2002 Hewlett-Packard Company
   5  * Copyright 2005-2008 Pierre Ossman
   6  *
   7  * Use consistent with the GNU GPL is permitted,
   8  * provided that this copyright notice is
   9  * preserved in its entirety in all copies and derived works.
  10  *
  11  * HEWLETT-PACKARD COMPANY MAKES NO WARRANTIES, EXPRESSED OR IMPLIED,
  12  * AS TO THE USEFULNESS OR CORRECTNESS OF THIS CODE OR ITS
  13  * FITNESS FOR ANY PARTICULAR PURPOSE.
  14  *
  15  * Many thanks to Alessandro Rubini and Jonathan Corbet!
  16  *
  17  * Author:  Andrew Christian
  18  *          28 May 2002
  19  */
  20 #include <linux/moduleparam.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23
  24 #include <linux/kernel.h>
  25 #include <linux/fs.h>
  26 #include <linux/errno.h>
  27 #include <linux/hdreg.h>
  28 #include <linux/kdev_t.h>
  29 #include <linux/blkdev.h>
  30 #include <linux/mutex.h>
  31 #include <linux/scatterlist.h>
  32 #include <linux/string_helpers.h>
  33
  34 #include <linux/mmc/card.h>
  35 #include <linux/mmc/host.h>
  36 #include <linux/mmc/mmc.h>
  37 #include <linux/mmc/sd.h>
  38
  39 #include <asm/system.h>
  40 #include <asm/uaccess.h>
  41
  42 #include "queue.h"
  43
  44 MODULE_ALIAS("mmc:block");
  45
  46 /*
  47  * max 8 partitions per card
  48  */
  49 #define MMC_SHIFT       3
  50 #define MMC_NUM_MINORS  (256 >> MMC_SHIFT)
  51
  52 static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);
  53
  54 /*
  55  * There is one mmc_blk_data per slot.
  56  */
  57 struct mmc_blk_data {
  58         spinlock_t      lock;
  59         struct gendisk  *disk;
  60         struct mmc_queue queue;
  61
  62         unsigned int    usage;
  63         unsigned int    read_only;
  64 };
  65
  66 static DEFINE_MUTEX(open_lock);
  67
  68 static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
  69 {
  70         struct mmc_blk_data *md;
  71
  72         mutex_lock(&open_lock);
  73         md = disk->private_data;
  74         if (md && md->usage == 0)
  75                 md = NULL;
  76         if (md)
  77                 md->usage++;
  78         mutex_unlock(&open_lock);
  79
  80         return md;
  81 }
  82
  83 static void mmc_blk_put(struct mmc_blk_data *md)
  84 {
  85         mutex_lock(&open_lock);
  86         md->usage--;
  87         if (md->usage == 0) {
  88                 int devidx = MINOR(disk_devt(md->disk)) >> MMC_SHIFT;
  89                 __clear_bit(devidx, dev_use);
  90
  91                 put_disk(md->disk);
  92                 kfree(md);
  93         }
  94         mutex_unlock(&open_lock);
  95 }
  96
  97 static int mmc_blk_open(struct block_device *bdev, fmode_t mode)
  98 {
  99         struct mmc_blk_data *md = mmc_blk_get(bdev->bd_disk);
 100         int ret = -ENXIO;
 101
 102         if (md) {
 103                 if (md->usage == 2)
 104                         check_disk_change(bdev);
 105                 ret = 0;
 106
 107                 if ((mode & FMODE_WRITE) && md->read_only) {
 108                         mmc_blk_put(md);
 109                         ret = -EROFS;
 110                 }
 111         }
 112
 113         return ret;
 114 }
 115
 116 static int mmc_blk_release(struct gendisk *disk, fmode_t mode)
 117 {
 118         struct mmc_blk_data *md = disk->private_data;
 119
 120         mmc_blk_put(md);
 121         return 0;
 122 }
 123
 124 static int
 125 mmc_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 126 {
 127         geo->cylinders = get_capacity(bdev->bd_disk) / (4 * 16);
 128         geo->heads = 4;
 129         geo->sectors = 16;
 130         return 0;
 131 }
 132
 133 static const struct block_device_operations mmc_bdops = {
 134         .open                   = mmc_blk_open,
 135         .release                = mmc_blk_release,
 136         .getgeo                 = mmc_blk_getgeo,
 137         .owner                  = THIS_MODULE,
 138 };
 139
 140 struct mmc_blk_request {
 141         struct mmc_request      mrq;
 142         struct mmc_command      cmd;
 143         struct mmc_command      stop;
 144         struct mmc_data         data;
 145 };
 146
 147 static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
 148 {
 149         int err;
 150         u32 result;
 151         __be32 *blocks;
 152
 153         struct mmc_request mrq;
 154         struct mmc_command cmd;
 155         struct mmc_data data;
 156         unsigned int timeout_us;
 157
 158         struct scatterlist sg;
 159
 160         memset(&cmd, 0, sizeof(struct mmc_command));
 161
 162         cmd.opcode = MMC_APP_CMD;
 163         cmd.arg = card->rca << 16;
 164         cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
 165
 166         err = mmc_wait_for_cmd(card->host, &cmd, 0);
 167         if (err)
 168                 return (u32)-1;
 169         if (!mmc_host_is_spi(card->host) && !(cmd.resp[0] & R1_APP_CMD))
 170                 return (u32)-1;
 171
 172         memset(&cmd, 0, sizeof(struct mmc_command));
 173
 174         cmd.opcode = SD_APP_SEND_NUM_WR_BLKS;
 175         cmd.arg = 0;
 176         cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
 177
 178         memset(&data, 0, sizeof(struct mmc_data));
 179
 180         data.timeout_ns = card->csd.tacc_ns * 100;
 181         data.timeout_clks = card->csd.tacc_clks * 100;
 182
 183         timeout_us = data.timeout_ns / 1000;
 184         timeout_us += data.timeout_clks * 1000 /
 185                 (card->host->ios.clock / 1000);
 186
 187         if (timeout_us > 100000) {
 188                 data.timeout_ns = 100000000;
 189                 data.timeout_clks = 0;
 190         }
 191
 192         data.blksz = 4;
 193         data.blocks = 1;
 194         data.flags = MMC_DATA_READ;
 195         data.sg = &sg;
 196         data.sg_len = 1;
 197
 198         memset(&mrq, 0, sizeof(struct mmc_request));
 199
 200         mrq.cmd = &cmd;
 201         mrq.data = &data;
 202
 203         blocks = kmalloc(4, GFP_KERNEL);
 204         if (!blocks)
 205                 return (u32)-1;
 206
 207         sg_init_one(&sg, blocks, 4);
 208
 209         mmc_wait_for_req(card->host, &mrq);
 210
 211         result = ntohl(*blocks);
 212         kfree(blocks);
 213
 214         if (cmd.error || data.error)
 215                 result = (u32)-1;
 216
 217         return result;
 218 }
 219
 220 static u32 get_card_status(struct mmc_card *card, struct request *req)
 221 {
 222         struct mmc_command cmd;
 223         int err;
 224
 225         memset(&cmd, 0, sizeof(struct mmc_command));
 226         cmd.opcode = MMC_SEND_STATUS;
 227         if (!mmc_host_is_spi(card->host))
 228                 cmd.arg = card->rca << 16;
 229         cmd.flags = MMC_RSP_SPI_R2 | MMC_RSP_R1 | MMC_CMD_AC;
 230         err = mmc_wait_for_cmd(card->host, &cmd, 0);
 231         if (err)
 232                 printk(KERN_ERR "%s: error %d sending status comand",
 233                        req->rq_disk->disk_name, err);
 234         return cmd.resp[0];
 235 }
 236
 237 static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 238 {
 239         struct mmc_blk_data *md = mq->data;
 240         struct mmc_card *card = md->queue.card;
 241         struct mmc_blk_request brq;
 242         int ret = 1, disable_multi = 0;
 243
 244         mmc_claim_host(card->host);
 245
 246         do {
 247                 struct mmc_command cmd;
 248                 u32 readcmd, writecmd, status = 0;
 249
 250                 memset(&brq, 0, sizeof(struct mmc_blk_request));
 251                 brq.mrq.cmd = &brq.cmd;
 252                 brq.mrq.data = &brq.data;
 253
 254                 brq.cmd.arg = blk_rq_pos(req);
 255                 if (!mmc_card_blockaddr(card))
 256                         brq.cmd.arg <<= 9;
 257                 brq.cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
 258                 brq.data.blksz = 512;
 259                 brq.stop.opcode = MMC_STOP_TRANSMISSION;
 260                 brq.stop.arg = 0;
 261                 brq.stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
 262                 brq.data.blocks = blk_rq_sectors(req);
 263
 264                 /*
 265                  * The block layer doesn't support all sector count
 266                  * restrictions, so we need to be prepared for too big
 267                  * requests.
 268                  */
 269                 if (brq.data.blocks > card->host->max_blk_count)
 270                         brq.data.blocks = card->host->max_blk_count;
 271
 272                 /*
 273                  * After a read error, we redo the request one sector at a time
 274                  * in order to accurately determine which sectors can be read
 275                  * successfully.
 276                  */
 277                 if (disable_multi && brq.data.blocks > 1)
 278                         brq.data.blocks = 1;
 279
 280                 if (brq.data.blocks > 1) {
 281                         /* SPI multiblock writes terminate using a special
 282                          * token, not a STOP_TRANSMISSION request.
 283                          */
 284                         if (!mmc_host_is_spi(card->host)
 285                                         || rq_data_dir(req) == READ)
 286                                 brq.mrq.stop = &brq.stop;
 287                         readcmd = MMC_READ_MULTIPLE_BLOCK;
 288                         writecmd = MMC_WRITE_MULTIPLE_BLOCK;
 289                 } else {
 290                         brq.mrq.stop = NULL;
 291                         readcmd = MMC_READ_SINGLE_BLOCK;
 292                         writecmd = MMC_WRITE_BLOCK;
 293                 }
 294
 295                 if (rq_data_dir(req) == READ) {
 296                         brq.cmd.opcode = readcmd;
 297                         brq.data.flags |= MMC_DATA_READ;
 298                 } else {
 299                         brq.cmd.opcode = writecmd;
 300                         brq.data.flags |= MMC_DATA_WRITE;
 301                 }
 302
 303                 mmc_set_data_timeout(&brq.data, card);
 304
 305                 brq.data.sg = mq->sg;
 306                 brq.data.sg_len = mmc_queue_map_sg(mq);
 307
 308                 /*
 309                  * Adjust the sg list so it is the same size as the
 310                  * request.
 311                  */
 312                 if (brq.data.blocks != blk_rq_sectors(req)) {
 313                         int i, data_size = brq.data.blocks << 9;
 314                         struct scatterlist *sg;
 315
 316                         for_each_sg(brq.data.sg, sg, brq.data.sg_len, i) {
 317                                 data_size -= sg->length;
 318                                 if (data_size <= 0) {
 319                                         sg->length += data_size;
 320                                         i++;
 321                                         break;
 322                                 }
 323                         }
 324                         brq.data.sg_len = i;
 325                 }
 326
 327                 mmc_queue_bounce_pre(mq);
 328
 329                 mmc_wait_for_req(card->host, &brq.mrq);
 330
 331                 mmc_queue_bounce_post(mq);
 332
 333                 /*
 334                  * Check for errors here, but don't jump to cmd_err
 335                  * until later as we need to wait for the card to leave
 336                  * programming mode even when things go wrong.
 337                  */
 338                 if (brq.cmd.error || brq.data.error || brq.stop.error) {
 339                         if (brq.data.blocks > 1 && rq_data_dir(req) == READ) {
 340                                 /* Redo read one sector at a time */
 341                                 printk(KERN_WARNING "%s: retrying using single "
 342                                        "block read\n", req->rq_disk->disk_name);
 343                                 disable_multi = 1;
 344                                 continue;
 345                         }
 346                         status = get_card_status(card, req);
 347                 }
 348
 349                 if (brq.cmd.error) {
 350                         printk(KERN_ERR "%s: error %d sending read/write "
 351                                "command, response %#x, card status %#x\n",
 352                                req->rq_disk->disk_name, brq.cmd.error,
 353                                brq.cmd.resp[0], status);
 354                 }
 355
 356                 if (brq.data.error) {
 357                         if (brq.data.error == -ETIMEDOUT && brq.mrq.stop)
 358                                 /* 'Stop' response contains card status */
 359                                 status = brq.mrq.stop->resp[0];
 360                         printk(KERN_ERR "%s: error %d transferring data,"
 361                                " sector %u, nr %u, card status %#x\n",
 362                                req->rq_disk->disk_name, brq.data.error,
 363                                (unsigned)blk_rq_pos(req),
 364                                (unsigned)blk_rq_sectors(req), status);
 365                 }
 366
 367                 if (brq.stop.error) {
 368                         printk(KERN_ERR "%s: error %d sending stop command, "
 369                                "response %#x, card status %#x\n",
 370                                req->rq_disk->disk_name, brq.stop.error,
 371                                brq.stop.resp[0], status);
 372                 }
 373
 374                 if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ) {
 375                         do {
 376                                 int err;
 377
 378                                 cmd.opcode = MMC_SEND_STATUS;
 379                                 cmd.arg = card->rca << 16;
 380                                 cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 381                                 err = mmc_wait_for_cmd(card->host, &cmd, 5);
 382                                 if (err) {
 383                                         printk(KERN_ERR "%s: error %d requesting status\n",
 384                                                req->rq_disk->disk_name, err);
 385                                         goto cmd_err;
 386                                 }
 387                                 /*
 388                                  * Some cards mishandle the status bits,
 389                                  * so make sure to check both the busy
 390                                  * indication and the card state.
 391                                  */
 392                         } while (!(cmd.resp[0] & R1_READY_FOR_DATA) ||
 393                                 (R1_CURRENT_STATE(cmd.resp[0]) == 7));
 394
 395 #if 0
 396                         if (cmd.resp[0] & ~0x00000900)
 397                                 printk(KERN_ERR "%s: status = %08x\n",
 398                                        req->rq_disk->disk_name, cmd.resp[0]);
 399                         if (mmc_decode_status(cmd.resp))
 400                                 goto cmd_err;
 401 #endif
 402                 }
 403
 404                 if (brq.cmd.error || brq.stop.error || brq.data.error) {
 405                         if (rq_data_dir(req) == READ) {
 406                                 /*
 407                                  * After an error, we redo I/O one sector at a
 408                                  * time, so we only reach here after trying to
 409                                  * read a single sector.
 410                                  */
 411                                 spin_lock_irq(&md->lock);
 412                                 ret = __blk_end_request(req, -EIO, brq.data.blksz);
 413                                 spin_unlock_irq(&md->lock);
 414                                 continue;
 415                         }
 416                         goto cmd_err;
 417                 }
 418
 419                 /*
 420                  * A block was successfully transferred.
 421                  */
 422                 spin_lock_irq(&md->lock);
 423                 ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
 424                 spin_unlock_irq(&md->lock);
 425         } while (ret);
 426
 427         mmc_release_host(card->host);
 428
 429         return 1;
 430
 431  cmd_err:
 432         /*
 433          * If this is an SD card and we're writing, we can first
 434          * mark the known good sectors as ok.
 435          *
 436          * If the card is not SD, we can still ok written sectors
 437          * as reported by the controller (which might be less than
 438          * the real number of written sectors, but never more).
 439          */
 440         if (mmc_card_sd(card)) {
 441                 u32 blocks;
 442
 443                 blocks = mmc_sd_num_wr_blocks(card);
 444                 if (blocks != (u32)-1) {
 445                         spin_lock_irq(&md->lock);
 446                         ret = __blk_end_request(req, 0, blocks << 9);
 447                         spin_unlock_irq(&md->lock);
 448                 }
 449         } else {
 450                 spin_lock_irq(&md->lock);
 451                 ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
 452                 spin_unlock_irq(&md->lock);
 453         }
 454
 455         mmc_release_host(card->host);
 456
 457         spin_lock_irq(&md->lock);
 458         while (ret)
 459                 ret = __blk_end_request(req, -EIO, blk_rq_cur_bytes(req));
 460         spin_unlock_irq(&md->lock);
 461
 462         return 0;
 463 }
 464
 465
 466 static inline int mmc_blk_readonly(struct mmc_card *card)
 467 {
 468         return mmc_card_readonly(card) ||
 469                !(card->csd.cmdclass & CCC_BLOCK_WRITE);
 470 }
 471
 472 static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
 473 {
 474         struct mmc_blk_data *md;
 475         int devidx, ret;
 476
 477         devidx = find_first_zero_bit(dev_use, MMC_NUM_MINORS);
 478         if (devidx >= MMC_NUM_MINORS)
 479                 return ERR_PTR(-ENOSPC);
 480         __set_bit(devidx, dev_use);
 481
 482         md = kzalloc(sizeof(struct mmc_blk_data), GFP_KERNEL);
 483         if (!md) {
 484                 ret = -ENOMEM;
 485                 goto out;
 486         }
 487
 488
 489         /*
 490          * Set the read-only status based on the supported commands
 491          * and the write protect switch.
 492          */
 493         md->read_only = mmc_blk_readonly(card);
 494
 495         md->disk = alloc_disk(1 << MMC_SHIFT);
 496         if (md->disk == NULL) {
 497                 ret = -ENOMEM;
 498                 goto err_kfree;
 499         }
 500
 501         spin_lock_init(&md->lock);
 502         md->usage = 1;
 503
 504         ret = mmc_init_queue(&md->queue, card, &md->lock);
 505         if (ret)
 506                 goto err_putdisk;
 507
 508         md->queue.issue_fn = mmc_blk_issue_rq;
 509         md->queue.data = md;
 510
 511         md->disk->major = MMC_BLOCK_MAJOR;
 512         md->disk->first_minor = devidx << MMC_SHIFT;
 513         md->disk->fops = &mmc_bdops;
 514         md->disk->private_data = md;
 515         md->disk->queue = md->queue.queue;
 516         md->disk->driverfs_dev = &card->dev;
 517
 518         /*
 519          * As discussed on lkml, GENHD_FL_REMOVABLE should:
 520          *
 521          * - be set for removable media with permanent block devices
 522          * - be unset for removable block devices with permanent media
 523          *
 524          * Since MMC block devices clearly fall under the second
 525          * case, we do not set GENHD_FL_REMOVABLE.  Userspace
 526          * should use the block device creation/destruction hotplug
 527          * messages to tell when the card is present.
 528          */
 529
 530         sprintf(md->disk->disk_name, "mmcblk%d", devidx);
 531
 532         blk_queue_logical_block_size(md->queue.queue, 512);
 533
 534         if (!mmc_card_sd(card) && mmc_card_blockaddr(card)) {
 535                 /*
 536                  * The EXT_CSD sector count is in number or 512 byte
 537                  * sectors.
 538                  */
 539                 set_capacity(md->disk, card->ext_csd.sectors);
 540         } else {
 541                 /*
 542                  * The CSD capacity field is in units of read_blkbits.
 543                  * set_capacity takes units of 512 bytes.
 544                  */
 545                 set_capacity(md->disk,
 546                         card->csd.capacity << (card->csd.read_blkbits - 9));
 547         }
 548         return md;
 549
 550  err_putdisk:
 551         put_disk(md->disk);
 552  err_kfree:
 553         kfree(md);
 554  out:
 555         return ERR_PTR(ret);
 556 }
 557
 558 static int
 559 mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
 560 {
 561         struct mmc_command cmd;
 562         int err;
 563
 564         /* Block-addressed cards ignore MMC_SET_BLOCKLEN. */
 565         if (mmc_card_blockaddr(card))
 566                 return 0;
 567
 568         mmc_claim_host(card->host);
 569         cmd.opcode = MMC_SET_BLOCKLEN;
 570         cmd.arg = 512;
 571         cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
 572         err = mmc_wait_for_cmd(card->host, &cmd, 5);
 573         mmc_release_host(card->host);
 574
 575         if (err) {
 576                 printk(KERN_ERR "%s: unable to set block size to %d: %d\n",
 577                         md->disk->disk_name, cmd.arg, err);
 578                 return -EINVAL;
 579         }
 580
 581         return 0;
 582 }
 583
 584 static int mmc_blk_probe(struct mmc_card *card)
 585 {
 586         struct mmc_blk_data *md;
 587         int err;
 588
 589         char cap_str[10];
 590
 591         /*
 592          * Check that the card supports the command class(es) we need.
 593          */
 594         if (!(card->csd.cmdclass & CCC_BLOCK_READ))
 595                 return -ENODEV;
 596
 597         md = mmc_blk_alloc(card);
 598         if (IS_ERR(md))
 599                 return PTR_ERR(md);
 600
 601         err = mmc_blk_set_blksize(md, card);
 602         if (err)
 603                 goto out;
 604
 605         string_get_size((u64)get_capacity(md->disk) << 9, STRING_UNITS_2,
 606                         cap_str, sizeof(cap_str));
 607         printk(KERN_INFO "%s: %s %s %s %s\n",
 608                 md->disk->disk_name, mmc_card_id(card), mmc_card_name(card),
 609                 cap_str, md->read_only ? "(ro)" : "");
 610
 611         mmc_set_drvdata(card, md);
 612         add_disk(md->disk);
 613         return 0;
 614
 615  out:
 616         mmc_blk_put(md);
 617
 618         return err;
 619 }
 620
 621 static void mmc_blk_remove(struct mmc_card *card)
 622 {
 623         struct mmc_blk_data *md = mmc_get_drvdata(card);
 624
 625         if (md) {
 626                 /* Stop new requests from getting into the queue */
 627                 del_gendisk(md->disk);
 628
 629                 /* Then flush out any already in there */
 630                 mmc_cleanup_queue(&md->queue);
 631
 632                 mmc_blk_put(md);
 633         }
 634         mmc_set_drvdata(card, NULL);
 635 }
 636
 637 #ifdef CONFIG_PM
 638 static int mmc_blk_suspend(struct mmc_card *card, pm_message_t state)
 639 {
 640         struct mmc_blk_data *md = mmc_get_drvdata(card);
 641
 642         if (md) {
 643                 mmc_queue_suspend(&md->queue);
 644         }
 645         return 0;
 646 }
 647
 648 static int mmc_blk_resume(struct mmc_card *card)
 649 {
 650         struct mmc_blk_data *md = mmc_get_drvdata(card);
 651
 652         if (md) {
 653                 mmc_blk_set_blksize(md, card);
 654                 mmc_queue_resume(&md->queue);
 655         }
 656         return 0;
 657 }
 658 #else
 659 #define mmc_blk_suspend NULL
 660 #define mmc_blk_resume  NULL
 661 #endif
 662
 663 static struct mmc_driver mmc_driver = {
 664         .drv            = {
 665                 .name   = "mmcblk",
 666         },
 667         .probe          = mmc_blk_probe,
 668         .remove         = mmc_blk_remove,
 669         .suspend        = mmc_blk_suspend,
 670         .resume         = mmc_blk_resume,
 671 };
 672
 673 static int __init mmc_blk_init(void)
 674 {
 675         int res;
 676
 677         res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");
 678         if (res)
 679                 goto out;
 680
 681         res = mmc_register_driver(&mmc_driver);
 682         if (res)
 683                 goto out2;
 684
 685         return 0;
 686  out2:
 687         unregister_blkdev(MMC_BLOCK_MAJOR, "mmc");
 688  out:
 689         return res;
 690 }
 691
 692 static void __exit mmc_blk_exit(void)
 693 {
 694         mmc_unregister_driver(&mmc_driver);
 695         unregister_blkdev(MMC_BLOCK_MAJOR, "mmc");
 696 }
 697
 698 module_init(mmc_blk_init);
 699 module_exit(mmc_blk_exit);
 700
 701 MODULE_LICENSE("GPL");
 702 MODULE_DESCRIPTION("Multimedia Card (MMC) block device driver");
 703