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