git.oblomov.eu Git - linux-2.6/blob - arch/arm/common/dmabounce.c

   1 /*
   2  *  arch/arm/common/dmabounce.c
   3  *
   4  *  Special dma_{map/unmap/dma_sync}_* routines for systems that have
   5  *  limited DMA windows. These functions utilize bounce buffers to
   6  *  copy data to/from buffers located outside the DMA region. This
   7  *  only works for systems in which DMA memory is at the bottom of
   8  *  RAM and the remainder of memory is at the top an the DMA memory
   9  *  can be marked as ZONE_DMA. Anything beyond that such as discontigous
  10  *  DMA windows will require custom implementations that reserve memory
  11  *  areas at early bootup.
  12  *
  13  *  Original version by Brad Parker (brad@heeltoe.com)
  14  *  Re-written by Christopher Hoover <ch@murgatroid.com>
  15  *  Made generic by Deepak Saxena <dsaxena@plexity.net>
  16  *
  17  *  Copyright (C) 2002 Hewlett Packard Company.
  18  *  Copyright (C) 2004 MontaVista Software, Inc.
  19  *
  20  *  This program is free software; you can redistribute it and/or
  21  *  modify it under the terms of the GNU General Public License
  22  *  version 2 as published by the Free Software Foundation.
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/slab.h>
  28 #include <linux/device.h>
  29 #include <linux/dma-mapping.h>
  30 #include <linux/dmapool.h>
  31 #include <linux/list.h>
  32
  33 #include <asm/cacheflush.h>
  34
  35 #undef DEBUG
  36
  37 #undef STATS
  38 #ifdef STATS
  39 #define DO_STATS(X) do { X ; } while (0)
  40 #else
  41 #define DO_STATS(X) do { } while (0)
  42 #endif
  43
  44 /* ************************************************** */
  45
  46 struct safe_buffer {
  47         struct list_head node;
  48
  49         /* original request */
  50         void            *ptr;
  51         size_t          size;
  52         int             direction;
  53
  54         /* safe buffer info */
  55         struct dma_pool *pool;
  56         void            *safe;
  57         dma_addr_t      safe_dma_addr;
  58 };
  59
  60 struct dmabounce_device_info {
  61         struct list_head node;
  62
  63         struct device *dev;
  64         struct dma_pool *small_buffer_pool;
  65         struct dma_pool *large_buffer_pool;
  66         struct list_head safe_buffers;
  67         unsigned long small_buffer_size, large_buffer_size;
  68 #ifdef STATS
  69         unsigned long sbp_allocs;
  70         unsigned long lbp_allocs;
  71         unsigned long total_allocs;
  72         unsigned long map_op_count;
  73         unsigned long bounce_count;
  74 #endif
  75 };
  76
  77 static LIST_HEAD(dmabounce_devs);
  78
  79 #ifdef STATS
  80 static void print_alloc_stats(struct dmabounce_device_info *device_info)
  81 {
  82         printk(KERN_INFO
  83                 "%s: dmabounce: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
  84                 device_info->dev->bus_id,
  85                 device_info->sbp_allocs, device_info->lbp_allocs,
  86                 device_info->total_allocs - device_info->sbp_allocs -
  87                         device_info->lbp_allocs,
  88                 device_info->total_allocs);
  89 }
  90 #endif
  91
  92 /* find the given device in the dmabounce device list */
  93 static inline struct dmabounce_device_info *
  94 find_dmabounce_dev(struct device *dev)
  95 {
  96         struct list_head *entry;
  97
  98         list_for_each(entry, &dmabounce_devs) {
  99                 struct dmabounce_device_info *d =
 100                         list_entry(entry, struct dmabounce_device_info, node);
 101
 102                 if (d->dev == dev)
 103                         return d;
 104         }
 105         return NULL;
 106 }
 107
 108
 109 /* allocate a 'safe' buffer and keep track of it */
 110 static inline struct safe_buffer *
 111 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 112                         size_t size, enum dma_data_direction dir)
 113 {
 114         struct safe_buffer *buf;
 115         struct dma_pool *pool;
 116         struct device *dev = device_info->dev;
 117         void *safe;
 118         dma_addr_t safe_dma_addr;
 119
 120         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 121                 __func__, ptr, size, dir);
 122
 123         DO_STATS ( device_info->total_allocs++ );
 124
 125         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 126         if (buf == NULL) {
 127                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 128                 return NULL;
 129         }
 130
 131         if (size <= device_info->small_buffer_size) {
 132                 pool = device_info->small_buffer_pool;
 133                 safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 134
 135                 DO_STATS ( device_info->sbp_allocs++ );
 136         } else if (size <= device_info->large_buffer_size) {
 137                 pool = device_info->large_buffer_pool;
 138                 safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 139
 140                 DO_STATS ( device_info->lbp_allocs++ );
 141         } else {
 142                 pool = NULL;
 143                 safe = dma_alloc_coherent(dev, size, &safe_dma_addr, GFP_ATOMIC);
 144         }
 145
 146         if (safe == NULL) {
 147                 dev_warn(device_info->dev,
 148                         "%s: could not alloc dma memory (size=%d)\n",
 149                        __func__, size);
 150                 kfree(buf);
 151                 return NULL;
 152         }
 153
 154 #ifdef STATS
 155         if (device_info->total_allocs % 1000 == 0)
 156                 print_alloc_stats(device_info);
 157 #endif
 158
 159         buf->ptr = ptr;
 160         buf->size = size;
 161         buf->direction = dir;
 162         buf->pool = pool;
 163         buf->safe = safe;
 164         buf->safe_dma_addr = safe_dma_addr;
 165
 166         list_add(&buf->node, &device_info->safe_buffers);
 167
 168         return buf;
 169 }
 170
 171 /* determine if a buffer is from our "safe" pool */
 172 static inline struct safe_buffer *
 173 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 174 {
 175         struct list_head *entry;
 176
 177         list_for_each(entry, &device_info->safe_buffers) {
 178                 struct safe_buffer *b =
 179                         list_entry(entry, struct safe_buffer, node);
 180
 181                 if (b->safe_dma_addr == safe_dma_addr)
 182                         return b;
 183         }
 184
 185         return NULL;
 186 }
 187
 188 static inline void
 189 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 190 {
 191         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 192
 193         list_del(&buf->node);
 194
 195         if (buf->pool)
 196                 dma_pool_free(buf->pool, buf->safe, buf->safe_dma_addr);
 197         else
 198                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 199                                     buf->safe_dma_addr);
 200
 201         kfree(buf);
 202 }
 203
 204 /* ************************************************** */
 205
 206 #ifdef STATS
 207
 208 static void print_map_stats(struct dmabounce_device_info *device_info)
 209 {
 210         printk(KERN_INFO
 211                 "%s: dmabounce: map_op_count=%lu, bounce_count=%lu\n",
 212                 device_info->dev->bus_id,
 213                 device_info->map_op_count, device_info->bounce_count);
 214 }
 215 #endif
 216
 217 static inline dma_addr_t
 218 map_single(struct device *dev, void *ptr, size_t size,
 219                 enum dma_data_direction dir)
 220 {
 221         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 222         dma_addr_t dma_addr;
 223         int needs_bounce = 0;
 224
 225         if (device_info)
 226                 DO_STATS ( device_info->map_op_count++ );
 227
 228         dma_addr = virt_to_dma(dev, ptr);
 229
 230         if (dev->dma_mask) {
 231                 unsigned long mask = *dev->dma_mask;
 232                 unsigned long limit;
 233
 234                 limit = (mask + 1) & ~mask;
 235                 if (limit && size > limit) {
 236                         dev_err(dev, "DMA mapping too big (requested %#x "
 237                                 "mask %#Lx)\n", size, *dev->dma_mask);
 238                         return ~0;
 239                 }
 240
 241                 /*
 242                  * Figure out if we need to bounce from the DMA mask.
 243                  */
 244                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 245         }
 246
 247         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 248                 struct safe_buffer *buf;
 249
 250                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 251                 if (buf == 0) {
 252                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 253                                __func__, ptr);
 254                         return 0;
 255                 }
 256
 257                 dev_dbg(dev,
 258                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 259                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 260                         buf->safe, (void *) buf->safe_dma_addr);
 261
 262                 if ((dir == DMA_TO_DEVICE) ||
 263                     (dir == DMA_BIDIRECTIONAL)) {
 264                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 265                                 __func__, ptr, buf->safe, size);
 266                         memcpy(buf->safe, ptr, size);
 267                 }
 268                 consistent_sync(buf->safe, size, dir);
 269
 270                 dma_addr = buf->safe_dma_addr;
 271         } else {
 272                 consistent_sync(ptr, size, dir);
 273         }
 274
 275         return dma_addr;
 276 }
 277
 278 static inline void
 279 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 280                 enum dma_data_direction dir)
 281 {
 282         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 283         struct safe_buffer *buf = NULL;
 284
 285         /*
 286          * Trying to unmap an invalid mapping
 287          */
 288         if (dma_addr == ~0) {
 289                 dev_err(dev, "Trying to unmap invalid mapping\n");
 290                 return;
 291         }
 292
 293         if (device_info)
 294                 buf = find_safe_buffer(device_info, dma_addr);
 295
 296         if (buf) {
 297                 BUG_ON(buf->size != size);
 298
 299                 dev_dbg(dev,
 300                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 301                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 302                         buf->safe, (void *) buf->safe_dma_addr);
 303
 304
 305                 DO_STATS ( device_info->bounce_count++ );
 306
 307                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 308                         unsigned long ptr;
 309
 310                         dev_dbg(dev,
 311                                 "%s: copy back safe %p to unsafe %p size %d\n",
 312                                 __func__, buf->safe, buf->ptr, size);
 313                         memcpy(buf->ptr, buf->safe, size);
 314
 315                         /*
 316                          * DMA buffers must have the same cache properties
 317                          * as if they were really used for DMA - which means
 318                          * data must be written back to RAM.  Note that
 319                          * we don't use dmac_flush_range() here for the
 320                          * bidirectional case because we know the cache
 321                          * lines will be coherent with the data written.
 322                          */
 323                         ptr = (unsigned long)buf->ptr;
 324                         dmac_clean_range(ptr, ptr + size);
 325                 }
 326                 free_safe_buffer(device_info, buf);
 327         }
 328 }
 329
 330 static inline void
 331 sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 332                 enum dma_data_direction dir)
 333 {
 334         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 335         struct safe_buffer *buf = NULL;
 336
 337         if (device_info)
 338                 buf = find_safe_buffer(device_info, dma_addr);
 339
 340         if (buf) {
 341                 /*
 342                  * Both of these checks from original code need to be
 343                  * commented out b/c some drivers rely on the following:
 344                  *
 345                  * 1) Drivers may map a large chunk of memory into DMA space
 346                  *    but only sync a small portion of it. Good example is
 347                  *    allocating a large buffer, mapping it, and then
 348                  *    breaking it up into small descriptors. No point
 349                  *    in syncing the whole buffer if you only have to
 350                  *    touch one descriptor.
 351                  *
 352                  * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
 353                  *    usually only synced in one dir at a time.
 354                  *
 355                  * See drivers/net/eepro100.c for examples of both cases.
 356                  *
 357                  * -ds
 358                  *
 359                  * BUG_ON(buf->size != size);
 360                  * BUG_ON(buf->direction != dir);
 361                  */
 362
 363                 dev_dbg(dev,
 364                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 365                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 366                         buf->safe, (void *) buf->safe_dma_addr);
 367
 368                 DO_STATS ( device_info->bounce_count++ );
 369
 370                 switch (dir) {
 371                 case DMA_FROM_DEVICE:
 372                         dev_dbg(dev,
 373                                 "%s: copy back safe %p to unsafe %p size %d\n",
 374                                 __func__, buf->safe, buf->ptr, size);
 375                         memcpy(buf->ptr, buf->safe, size);
 376                         break;
 377                 case DMA_TO_DEVICE:
 378                         dev_dbg(dev,
 379                                 "%s: copy out unsafe %p to safe %p, size %d\n",
 380                                 __func__,buf->ptr, buf->safe, size);
 381                         memcpy(buf->safe, buf->ptr, size);
 382                         break;
 383                 case DMA_BIDIRECTIONAL:
 384                         BUG();  /* is this allowed?  what does it mean? */
 385                 default:
 386                         BUG();
 387                 }
 388                 consistent_sync(buf->safe, size, dir);
 389         } else {
 390                 consistent_sync(dma_to_virt(dev, dma_addr), size, dir);
 391         }
 392 }
 393
 394 /* ************************************************** */
 395
 396 /*
 397  * see if a buffer address is in an 'unsafe' range.  if it is
 398  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 399  * substitute the safe buffer for the unsafe one.
 400  * (basically move the buffer from an unsafe area to a safe one)
 401  */
 402 dma_addr_t
 403 dma_map_single(struct device *dev, void *ptr, size_t size,
 404                 enum dma_data_direction dir)
 405 {
 406         unsigned long flags;
 407         dma_addr_t dma_addr;
 408
 409         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 410                 __func__, ptr, size, dir);
 411
 412         BUG_ON(dir == DMA_NONE);
 413
 414         local_irq_save(flags);
 415
 416         dma_addr = map_single(dev, ptr, size, dir);
 417
 418         local_irq_restore(flags);
 419
 420         return dma_addr;
 421 }
 422
 423 /*
 424  * see if a mapped address was really a "safe" buffer and if so, copy
 425  * the data from the safe buffer back to the unsafe buffer and free up
 426  * the safe buffer.  (basically return things back to the way they
 427  * should be)
 428  */
 429
 430 void
 431 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 432                         enum dma_data_direction dir)
 433 {
 434         unsigned long flags;
 435
 436         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 437                 __func__, (void *) dma_addr, size, dir);
 438
 439         BUG_ON(dir == DMA_NONE);
 440
 441         local_irq_save(flags);
 442
 443         unmap_single(dev, dma_addr, size, dir);
 444
 445         local_irq_restore(flags);
 446 }
 447
 448 int
 449 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 450                 enum dma_data_direction dir)
 451 {
 452         unsigned long flags;
 453         int i;
 454
 455         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 456                 __func__, sg, nents, dir);
 457
 458         BUG_ON(dir == DMA_NONE);
 459
 460         local_irq_save(flags);
 461
 462         for (i = 0; i < nents; i++, sg++) {
 463                 struct page *page = sg->page;
 464                 unsigned int offset = sg->offset;
 465                 unsigned int length = sg->length;
 466                 void *ptr = page_address(page) + offset;
 467
 468                 sg->dma_address =
 469                         map_single(dev, ptr, length, dir);
 470         }
 471
 472         local_irq_restore(flags);
 473
 474         return nents;
 475 }
 476
 477 void
 478 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 479                 enum dma_data_direction dir)
 480 {
 481         unsigned long flags;
 482         int i;
 483
 484         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 485                 __func__, sg, nents, dir);
 486
 487         BUG_ON(dir == DMA_NONE);
 488
 489         local_irq_save(flags);
 490
 491         for (i = 0; i < nents; i++, sg++) {
 492                 dma_addr_t dma_addr = sg->dma_address;
 493                 unsigned int length = sg->length;
 494
 495                 unmap_single(dev, dma_addr, length, dir);
 496         }
 497
 498         local_irq_restore(flags);
 499 }
 500
 501 void
 502 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
 503                                 enum dma_data_direction dir)
 504 {
 505         unsigned long flags;
 506
 507         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 508                 __func__, (void *) dma_addr, size, dir);
 509
 510         local_irq_save(flags);
 511
 512         sync_single(dev, dma_addr, size, dir);
 513
 514         local_irq_restore(flags);
 515 }
 516
 517 void
 518 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
 519                                 enum dma_data_direction dir)
 520 {
 521         unsigned long flags;
 522
 523         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 524                 __func__, (void *) dma_addr, size, dir);
 525
 526         local_irq_save(flags);
 527
 528         sync_single(dev, dma_addr, size, dir);
 529
 530         local_irq_restore(flags);
 531 }
 532
 533 void
 534 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 535                         enum dma_data_direction dir)
 536 {
 537         unsigned long flags;
 538         int i;
 539
 540         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 541                 __func__, sg, nents, dir);
 542
 543         BUG_ON(dir == DMA_NONE);
 544
 545         local_irq_save(flags);
 546
 547         for (i = 0; i < nents; i++, sg++) {
 548                 dma_addr_t dma_addr = sg->dma_address;
 549                 unsigned int length = sg->length;
 550
 551                 sync_single(dev, dma_addr, length, dir);
 552         }
 553
 554         local_irq_restore(flags);
 555 }
 556
 557 void
 558 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 559                         enum dma_data_direction dir)
 560 {
 561         unsigned long flags;
 562         int i;
 563
 564         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 565                 __func__, sg, nents, dir);
 566
 567         BUG_ON(dir == DMA_NONE);
 568
 569         local_irq_save(flags);
 570
 571         for (i = 0; i < nents; i++, sg++) {
 572                 dma_addr_t dma_addr = sg->dma_address;
 573                 unsigned int length = sg->length;
 574
 575                 sync_single(dev, dma_addr, length, dir);
 576         }
 577
 578         local_irq_restore(flags);
 579 }
 580
 581 int
 582 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 583                         unsigned long large_buffer_size)
 584 {
 585         struct dmabounce_device_info *device_info;
 586
 587         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 588         if (!device_info) {
 589                 printk(KERN_ERR
 590                         "Could not allocated dmabounce_device_info for %s",
 591                         dev->bus_id);
 592                 return -ENOMEM;
 593         }
 594
 595         device_info->small_buffer_pool =
 596                 dma_pool_create("small_dmabounce_pool",
 597                                 dev,
 598                                 small_buffer_size,
 599                                 0 /* byte alignment */,
 600                                 0 /* no page-crossing issues */);
 601         if (!device_info->small_buffer_pool) {
 602                 printk(KERN_ERR
 603                         "dmabounce: could not allocate small DMA pool for %s\n",
 604                         dev->bus_id);
 605                 kfree(device_info);
 606                 return -ENOMEM;
 607         }
 608
 609         if (large_buffer_size) {
 610                 device_info->large_buffer_pool =
 611                         dma_pool_create("large_dmabounce_pool",
 612                                         dev,
 613                                         large_buffer_size,
 614                                         0 /* byte alignment */,
 615                                         0 /* no page-crossing issues */);
 616                 if (!device_info->large_buffer_pool) {
 617                 printk(KERN_ERR
 618                         "dmabounce: could not allocate large DMA pool for %s\n",
 619                         dev->bus_id);
 620                         dma_pool_destroy(device_info->small_buffer_pool);
 621
 622                         return -ENOMEM;
 623                 }
 624         }
 625
 626         device_info->dev = dev;
 627         device_info->small_buffer_size = small_buffer_size;
 628         device_info->large_buffer_size = large_buffer_size;
 629         INIT_LIST_HEAD(&device_info->safe_buffers);
 630
 631 #ifdef STATS
 632         device_info->sbp_allocs = 0;
 633         device_info->lbp_allocs = 0;
 634         device_info->total_allocs = 0;
 635         device_info->map_op_count = 0;
 636         device_info->bounce_count = 0;
 637 #endif
 638
 639         list_add(&device_info->node, &dmabounce_devs);
 640
 641         printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
 642                 dev->bus_id, dev->bus->name);
 643
 644         return 0;
 645 }
 646
 647 void
 648 dmabounce_unregister_dev(struct device *dev)
 649 {
 650         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 651
 652         if (!device_info) {
 653                 printk(KERN_WARNING
 654                         "%s: Never registered with dmabounce but attempting" \
 655                         "to unregister!\n", dev->bus_id);
 656                 return;
 657         }
 658
 659         if (!list_empty(&device_info->safe_buffers)) {
 660                 printk(KERN_ERR
 661                         "%s: Removing from dmabounce with pending buffers!\n",
 662                         dev->bus_id);
 663                 BUG();
 664         }
 665
 666         if (device_info->small_buffer_pool)
 667                 dma_pool_destroy(device_info->small_buffer_pool);
 668         if (device_info->large_buffer_pool)
 669                 dma_pool_destroy(device_info->large_buffer_pool);
 670
 671 #ifdef STATS
 672         print_alloc_stats(device_info);
 673         print_map_stats(device_info);
 674 #endif
 675
 676         list_del(&device_info->node);
 677
 678         kfree(device_info);
 679
 680         printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
 681                 dev->bus_id, dev->bus->name);
 682 }
 683
 684
 685 EXPORT_SYMBOL(dma_map_single);
 686 EXPORT_SYMBOL(dma_unmap_single);
 687 EXPORT_SYMBOL(dma_map_sg);
 688 EXPORT_SYMBOL(dma_unmap_sg);
 689 EXPORT_SYMBOL(dma_sync_single);
 690 EXPORT_SYMBOL(dma_sync_sg);
 691 EXPORT_SYMBOL(dmabounce_register_dev);
 692 EXPORT_SYMBOL(dmabounce_unregister_dev);
 693
 694 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 695 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 696 MODULE_LICENSE("GPL");