linux-core/drm_bo_move.c

   1 /**************************************************************************
   2  *
   3  * Copyright (c) 2007 Tungsten Graphics, Inc., Cedar Park, TX., USA
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27 /*
  28  * Authors: Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  29  */
  30
  31 #include "drmP.h"
  32
  33 /**
  34  * Free the old memory node unless it's a pinned region and we
  35  * have not been requested to free also pinned regions.
  36  */
  37
  38 static void drm_bo_free_old_node(struct drm_buffer_object *bo)
  39 {
  40         struct drm_bo_mem_reg *old_mem = &bo->mem;
  41
  42         if (old_mem->mm_node && (old_mem->mm_node != bo->pinned_node)) {
  43                 mutex_lock(&bo->dev->struct_mutex);
  44                 drm_mm_put_block(old_mem->mm_node);
  45                 mutex_unlock(&bo->dev->struct_mutex);
  46         }
  47         old_mem->mm_node = NULL;
  48 }
  49
  50 int drm_bo_move_ttm(struct drm_buffer_object *bo,
  51                     int evict, int no_wait, struct drm_bo_mem_reg *new_mem)
  52 {
  53         struct drm_ttm *ttm = bo->ttm;
  54         struct drm_bo_mem_reg *old_mem = &bo->mem;
  55         uint64_t save_flags = old_mem->flags;
  56         uint64_t save_proposed_flags = old_mem->proposed_flags;
  57         int ret;
  58
  59         if (old_mem->mem_type != DRM_BO_MEM_LOCAL) {
  60                 if (evict)
  61                         drm_ttm_evict(ttm);
  62                 else
  63                         drm_ttm_unbind(ttm);
  64
  65                 drm_bo_free_old_node(bo);
  66                 DRM_FLAG_MASKED(old_mem->flags,
  67                                 DRM_BO_FLAG_CACHED | DRM_BO_FLAG_MAPPABLE |
  68                                 DRM_BO_FLAG_MEM_LOCAL, DRM_BO_MASK_MEMTYPE);
  69                 old_mem->mem_type = DRM_BO_MEM_LOCAL;
  70                 save_flags = old_mem->flags;
  71         }
  72         if (new_mem->mem_type != DRM_BO_MEM_LOCAL) {
  73                 ret = drm_ttm_bind(ttm, new_mem);
  74                 if (ret)
  75                         return ret;
  76         }
  77
  78         *old_mem = *new_mem;
  79         new_mem->mm_node = NULL;
  80         old_mem->proposed_flags = save_proposed_flags;
  81         DRM_FLAG_MASKED(save_flags, new_mem->flags, DRM_BO_MASK_MEMTYPE);
  82         return 0;
  83 }
  84 EXPORT_SYMBOL(drm_bo_move_ttm);
  85
  86 /**
  87  * \c Return a kernel virtual address to the buffer object PCI memory.
  88  *
  89  * \param bo The buffer object.
  90  * \return Failure indication.
  91  *
  92  * Returns -EINVAL if the buffer object is currently not mappable.
  93  * Returns -ENOMEM if the ioremap operation failed.
  94  * Otherwise returns zero.
  95  *
  96  * After a successfull call, bo->iomap contains the virtual address, or NULL
  97  * if the buffer object content is not accessible through PCI space.
  98  * Call bo->mutex locked.
  99  */
 100
 101 int drm_mem_reg_ioremap(struct drm_device *dev, struct drm_bo_mem_reg *mem,
 102                         void **virtual)
 103 {
 104         struct drm_buffer_manager *bm = &dev->bm;
 105         struct drm_mem_type_manager *man = &bm->man[mem->mem_type];
 106         unsigned long bus_offset;
 107         unsigned long bus_size;
 108         unsigned long bus_base;
 109         int ret;
 110         void *addr;
 111
 112         *virtual = NULL;
 113         ret = drm_bo_pci_offset(dev, mem, &bus_base, &bus_offset, &bus_size);
 114         if (ret || bus_size == 0)
 115                 return ret;
 116
 117         if (!(man->flags & _DRM_FLAG_NEEDS_IOREMAP))
 118                 addr = (void *)(((u8 *) man->io_addr) + bus_offset);
 119         else {
 120                 addr = ioremap_nocache(bus_base + bus_offset, bus_size);
 121                 if (!addr)
 122                         return -ENOMEM;
 123         }
 124         *virtual = addr;
 125         return 0;
 126 }
 127 EXPORT_SYMBOL(drm_mem_reg_ioremap);
 128
 129 /**
 130  * \c Unmap mapping obtained using drm_bo_ioremap
 131  *
 132  * \param bo The buffer object.
 133  *
 134  * Call bo->mutex locked.
 135  */
 136
 137 void drm_mem_reg_iounmap(struct drm_device *dev, struct drm_bo_mem_reg *mem,
 138                          void *virtual)
 139 {
 140         struct drm_buffer_manager *bm;
 141         struct drm_mem_type_manager *man;
 142
 143         bm = &dev->bm;
 144         man = &bm->man[mem->mem_type];
 145
 146         if (virtual && (man->flags & _DRM_FLAG_NEEDS_IOREMAP))
 147                 iounmap(virtual);
 148 }
 149
 150 static int drm_copy_io_page(void *dst, void *src, unsigned long page)
 151 {
 152         uint32_t *dstP =
 153             (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
 154         uint32_t *srcP =
 155             (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));
 156
 157         int i;
 158         for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
 159                 iowrite32(ioread32(srcP++), dstP++);
 160         return 0;
 161 }
 162
 163 static int drm_copy_io_ttm_page(struct drm_ttm *ttm, void *src,
 164                                 unsigned long page)
 165 {
 166         struct page *d = drm_ttm_get_page(ttm, page);
 167         void *dst;
 168
 169         if (!d)
 170                 return -ENOMEM;
 171
 172         src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
 173         dst = kmap(d);
 174         if (!dst)
 175                 return -ENOMEM;
 176
 177         memcpy_fromio(dst, src, PAGE_SIZE);
 178         kunmap(d);
 179         return 0;
 180 }
 181
 182 static int drm_copy_ttm_io_page(struct drm_ttm *ttm, void *dst, unsigned long page)
 183 {
 184         struct page *s = drm_ttm_get_page(ttm, page);
 185         void *src;
 186
 187         if (!s)
 188                 return -ENOMEM;
 189
 190         dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
 191         src = kmap(s);
 192         if (!src)
 193                 return -ENOMEM;
 194
 195         memcpy_toio(dst, src, PAGE_SIZE);
 196         kunmap(s);
 197         return 0;
 198 }
 199
 200 int drm_bo_move_memcpy(struct drm_buffer_object *bo,
 201                        int evict, int no_wait, struct drm_bo_mem_reg *new_mem)
 202 {
 203         struct drm_device *dev = bo->dev;
 204         struct drm_mem_type_manager *man = &dev->bm.man[new_mem->mem_type];
 205         struct drm_ttm *ttm = bo->ttm;
 206         struct drm_bo_mem_reg *old_mem = &bo->mem;
 207         struct drm_bo_mem_reg old_copy = *old_mem;
 208         void *old_iomap;
 209         void *new_iomap;
 210         int ret;
 211         uint64_t save_flags = old_mem->flags;
 212         uint64_t save_proposed_flags = old_mem->proposed_flags;
 213         unsigned long i;
 214         unsigned long page;
 215         unsigned long add = 0;
 216         int dir;
 217
 218         ret = drm_mem_reg_ioremap(dev, old_mem, &old_iomap);
 219         if (ret)
 220                 return ret;
 221         ret = drm_mem_reg_ioremap(dev, new_mem, &new_iomap);
 222         if (ret)
 223                 goto out;
 224
 225         if (old_iomap == NULL && new_iomap == NULL)
 226                 goto out2;
 227         if (old_iomap == NULL && ttm == NULL)
 228                 goto out2;
 229
 230         add = 0;
 231         dir = 1;
 232
 233         if ((old_mem->mem_type == new_mem->mem_type) &&
 234             (new_mem->mm_node->start <
 235              old_mem->mm_node->start + old_mem->mm_node->size)) {
 236                 dir = -1;
 237                 add = new_mem->num_pages - 1;
 238         }
 239
 240         for (i = 0; i < new_mem->num_pages; ++i) {
 241                 page = i * dir + add;
 242                 if (old_iomap == NULL)
 243                         ret = drm_copy_ttm_io_page(ttm, new_iomap, page);
 244                 else if (new_iomap == NULL)
 245                         ret = drm_copy_io_ttm_page(ttm, old_iomap, page);
 246                 else
 247                         ret = drm_copy_io_page(new_iomap, old_iomap, page);
 248                 if (ret)
 249                         goto out1;
 250         }
 251         mb();
 252 out2:
 253         drm_bo_free_old_node(bo);
 254
 255         *old_mem = *new_mem;
 256         new_mem->mm_node = NULL;
 257         old_mem->proposed_flags = save_proposed_flags;
 258         DRM_FLAG_MASKED(save_flags, new_mem->flags, DRM_BO_MASK_MEMTYPE);
 259
 260         if ((man->flags & _DRM_FLAG_MEMTYPE_FIXED) && (ttm != NULL)) {
 261                 drm_ttm_unbind(ttm);
 262                 drm_ttm_destroy(ttm);
 263                 bo->ttm = NULL;
 264         }
 265
 266 out1:
 267         drm_mem_reg_iounmap(dev, new_mem, new_iomap);
 268 out:
 269         drm_mem_reg_iounmap(dev, &old_copy, old_iomap);
 270         return ret;
 271 }
 272 EXPORT_SYMBOL(drm_bo_move_memcpy);
 273
 274 /*
 275  * Transfer a buffer object's memory and LRU status to a newly
 276  * created object. User-space references remains with the old
 277  * object. Call bo->mutex locked.
 278  */
 279
 280 int drm_buffer_object_transfer(struct drm_buffer_object *bo,
 281                                struct drm_buffer_object **new_obj)
 282 {
 283         struct drm_buffer_object *fbo;
 284         struct drm_device *dev = bo->dev;
 285         struct drm_buffer_manager *bm = &dev->bm;
 286
 287         fbo = drm_ctl_calloc(1, sizeof(*fbo), DRM_MEM_BUFOBJ);
 288         if (!fbo)
 289                 return -ENOMEM;
 290
 291         *fbo = *bo;
 292         mutex_init(&fbo->mutex);
 293         mutex_lock(&fbo->mutex);
 294         mutex_lock(&dev->struct_mutex);
 295
 296         DRM_INIT_WAITQUEUE(&bo->event_queue);
 297         INIT_LIST_HEAD(&fbo->ddestroy);
 298         INIT_LIST_HEAD(&fbo->lru);
 299         INIT_LIST_HEAD(&fbo->pinned_lru);
 300 #ifdef DRM_ODD_MM_COMPAT
 301         INIT_LIST_HEAD(&fbo->vma_list);
 302         INIT_LIST_HEAD(&fbo->p_mm_list);
 303 #endif
 304
 305         fbo->fence = drm_fence_reference_locked(bo->fence);
 306         fbo->pinned_node = NULL;
 307         fbo->mem.mm_node->private = (void *)fbo;
 308         atomic_set(&fbo->usage, 1);
 309         atomic_inc(&bm->count);
 310         mutex_unlock(&dev->struct_mutex);
 311         mutex_unlock(&fbo->mutex);
 312
 313         *new_obj = fbo;
 314         return 0;
 315 }
 316
 317 /*
 318  * Since move is underway, we need to block signals in this function.
 319  * We cannot restart until it has finished.
 320  */
 321
 322 int drm_bo_move_accel_cleanup(struct drm_buffer_object *bo,
 323                               int evict, int no_wait, uint32_t fence_class,
 324                               uint32_t fence_type, uint32_t fence_flags,
 325                               struct drm_bo_mem_reg *new_mem)
 326 {
 327         struct drm_device *dev = bo->dev;
 328         struct drm_mem_type_manager *man = &dev->bm.man[new_mem->mem_type];
 329         struct drm_bo_mem_reg *old_mem = &bo->mem;
 330         int ret;
 331         uint64_t save_flags = old_mem->flags;
 332         uint64_t save_proposed_flags = old_mem->proposed_flags;
 333         struct drm_buffer_object *old_obj;
 334
 335         if (bo->fence)
 336                 drm_fence_usage_deref_unlocked(&bo->fence);
 337         ret = drm_fence_object_create(dev, fence_class, fence_type,
 338                                       fence_flags | DRM_FENCE_FLAG_EMIT,
 339                                       &bo->fence);
 340         bo->fence_type = fence_type;
 341         if (ret)
 342                 return ret;
 343
 344 #ifdef DRM_ODD_MM_COMPAT
 345         /*
 346          * In this mode, we don't allow pipelining a copy blit,
 347          * since the buffer will be accessible from user space
 348          * the moment we return and rebuild the page tables.
 349          *
 350          * With normal vm operation, page tables are rebuilt
 351          * on demand using fault(), which waits for buffer idle.
 352          */
 353         if (1)
 354 #else
 355         if (evict || ((bo->mem.mm_node == bo->pinned_node) &&
 356                       bo->mem.mm_node != NULL))
 357 #endif
 358         {
 359                 ret = drm_bo_wait(bo, 0, 1, 0);
 360                 if (ret)
 361                         return ret;
 362
 363                 drm_bo_free_old_node(bo);
 364
 365                 if ((man->flags & _DRM_FLAG_MEMTYPE_FIXED) && (bo->ttm != NULL)) {
 366                         drm_ttm_unbind(bo->ttm);
 367                         drm_ttm_destroy(bo->ttm);
 368                         bo->ttm = NULL;
 369                 }
 370         } else {
 371
 372                 /* This should help pipeline ordinary buffer moves.
 373                  *
 374                  * Hang old buffer memory on a new buffer object,
 375                  * and leave it to be released when the GPU
 376                  * operation has completed.
 377                  */
 378
 379                 ret = drm_buffer_object_transfer(bo, &old_obj);
 380
 381                 if (ret)
 382                         return ret;
 383
 384                 if (!(man->flags & _DRM_FLAG_MEMTYPE_FIXED))
 385                         old_obj->ttm = NULL;
 386                 else
 387                         bo->ttm = NULL;
 388
 389                 mutex_lock(&dev->struct_mutex);
 390                 list_del_init(&old_obj->lru);
 391                 DRM_FLAG_MASKED(bo->priv_flags, 0, _DRM_BO_FLAG_UNFENCED);
 392                 drm_bo_add_to_lru(old_obj);
 393
 394                 drm_bo_usage_deref_locked(&old_obj);
 395                 mutex_unlock(&dev->struct_mutex);
 396
 397         }
 398
 399         *old_mem = *new_mem;
 400         new_mem->mm_node = NULL;
 401         old_mem->proposed_flags = save_proposed_flags;
 402         DRM_FLAG_MASKED(save_flags, new_mem->flags, DRM_BO_MASK_MEMTYPE);
 403         return 0;
 404 }
 405 EXPORT_SYMBOL(drm_bo_move_accel_cleanup);
 406
 407 int drm_bo_same_page(unsigned long offset,
 408                      unsigned long offset2)
 409 {
 410         return (offset & PAGE_MASK) == (offset2 & PAGE_MASK);
 411 }
 412 EXPORT_SYMBOL(drm_bo_same_page);
 413
 414 unsigned long drm_bo_offset_end(unsigned long offset,
 415                                 unsigned long end)
 416 {
 417         offset = (offset + PAGE_SIZE) & PAGE_MASK;
 418         return (end < offset) ? end : offset;
 419 }
 420 EXPORT_SYMBOL(drm_bo_offset_end);
 421
 422 static pgprot_t drm_kernel_io_prot(uint32_t map_type)
 423 {
 424         pgprot_t tmp = PAGE_KERNEL;
 425
 426 #if defined(__i386__) || defined(__x86_64__)
 427 #ifdef USE_PAT_WC
 428 #warning using pat
 429         if (drm_use_pat() && map_type == _DRM_TTM) {
 430                 pgprot_val(tmp) |= _PAGE_PAT;
 431                 return tmp;
 432         }
 433 #endif
 434         if (boot_cpu_data.x86 > 3 && map_type != _DRM_AGP) {
 435                 pgprot_val(tmp) |= _PAGE_PCD;
 436                 pgprot_val(tmp) &= ~_PAGE_PWT;
 437         }
 438 #elif defined(__powerpc__)
 439         pgprot_val(tmp) |= _PAGE_NO_CACHE;
 440         if (map_type == _DRM_REGISTERS)
 441                 pgprot_val(tmp) |= _PAGE_GUARDED;
 442 #endif
 443 #if defined(__ia64__)
 444         if (map_type == _DRM_TTM)
 445                 tmp = pgprot_writecombine(tmp);
 446         else
 447                 tmp = pgprot_noncached(tmp);
 448 #endif
 449         return tmp;
 450 }
 451
 452 static int drm_bo_ioremap(struct drm_buffer_object *bo, unsigned long bus_base,
 453                           unsigned long bus_offset, unsigned long bus_size,
 454                           struct drm_bo_kmap_obj *map)
 455 {
 456         struct drm_device *dev = bo->dev;
 457         struct drm_bo_mem_reg *mem = &bo->mem;
 458         struct drm_mem_type_manager *man = &dev->bm.man[mem->mem_type];
 459
 460         if (!(man->flags & _DRM_FLAG_NEEDS_IOREMAP)) {
 461                 map->bo_kmap_type = bo_map_premapped;
 462                 map->virtual = (void *)(((u8 *) man->io_addr) + bus_offset);
 463         } else {
 464                 map->bo_kmap_type = bo_map_iomap;
 465                 map->virtual = ioremap_nocache(bus_base + bus_offset, bus_size);
 466         }
 467         return (!map->virtual) ? -ENOMEM : 0;
 468 }
 469
 470 static int drm_bo_kmap_ttm(struct drm_buffer_object *bo,
 471                            unsigned long start_page, unsigned long num_pages,
 472                            struct drm_bo_kmap_obj *map)
 473 {
 474         struct drm_device *dev = bo->dev;
 475         struct drm_bo_mem_reg *mem = &bo->mem;
 476         struct drm_mem_type_manager *man = &dev->bm.man[mem->mem_type];
 477         pgprot_t prot;
 478         struct drm_ttm *ttm = bo->ttm;
 479         struct page *d;
 480         int i;
 481
 482         BUG_ON(!ttm);
 483
 484         if (num_pages == 1 && (mem->flags & DRM_BO_FLAG_CACHED)) {
 485
 486                 /*
 487                  * We're mapping a single page, and the desired
 488                  * page protection is consistent with the bo.
 489                  */
 490
 491                 map->bo_kmap_type = bo_map_kmap;
 492                 map->page = drm_ttm_get_page(ttm, start_page);
 493                 map->virtual = kmap(map->page);
 494         } else {
 495                 /*
 496                  * Populate the part we're mapping;
 497                  */
 498
 499                 for (i = start_page; i < start_page + num_pages; ++i) {
 500                         d = drm_ttm_get_page(ttm, i);
 501                         if (!d)
 502                                 return -ENOMEM;
 503                 }
 504
 505                 /*
 506                  * We need to use vmap to get the desired page protection
 507                  * or to make the buffer object look contigous.
 508                  */
 509
 510                 prot = (mem->flags & DRM_BO_FLAG_CACHED) ?
 511                         PAGE_KERNEL :
 512                         drm_kernel_io_prot(man->drm_bus_maptype);
 513                 map->bo_kmap_type = bo_map_vmap;
 514                 map->virtual = vmap(ttm->pages + start_page,
 515                                     num_pages, 0, prot);
 516         }
 517         return (!map->virtual) ? -ENOMEM : 0;
 518 }
 519
 520 /*
 521  * This function is to be used for kernel mapping of buffer objects.
 522  * It chooses the appropriate mapping method depending on the memory type
 523  * and caching policy the buffer currently has.
 524  * Mapping multiple pages or buffers that live in io memory is a bit slow and
 525  * consumes vmalloc space. Be restrictive with such mappings.
 526  * Mapping single pages usually returns the logical kernel address,
 527  * (which is fast)
 528  * BUG may use slower temporary mappings for high memory pages or
 529  * uncached / write-combined pages.
 530  *
 531  * The function fills in a drm_bo_kmap_obj which can be used to return the
 532  * kernel virtual address of the buffer.
 533  *
 534  * Code servicing a non-priviliged user request is only allowed to map one
 535  * page at a time. We might need to implement a better scheme to stop such
 536  * processes from consuming all vmalloc space.
 537  */
 538
 539 int drm_bo_kmap(struct drm_buffer_object *bo, unsigned long start_page,
 540                 unsigned long num_pages, struct drm_bo_kmap_obj *map)
 541 {
 542         int ret;
 543         unsigned long bus_base;
 544         unsigned long bus_offset;
 545         unsigned long bus_size;
 546
 547         map->virtual = NULL;
 548
 549         if (num_pages > bo->num_pages)
 550                 return -EINVAL;
 551         if (start_page > bo->num_pages)
 552                 return -EINVAL;
 553 #if 0
 554         if (num_pages > 1 && !DRM_SUSER(DRM_CURPROC))
 555                 return -EPERM;
 556 #endif
 557         ret = drm_bo_pci_offset(bo->dev, &bo->mem, &bus_base,
 558                                 &bus_offset, &bus_size);
 559
 560         if (ret)
 561                 return ret;
 562
 563         if (bus_size == 0) {
 564                 return drm_bo_kmap_ttm(bo, start_page, num_pages, map);
 565         } else {
 566                 bus_offset += start_page << PAGE_SHIFT;
 567                 bus_size = num_pages << PAGE_SHIFT;
 568                 return drm_bo_ioremap(bo, bus_base, bus_offset, bus_size, map);
 569         }
 570 }
 571 EXPORT_SYMBOL(drm_bo_kmap);
 572
 573 void drm_bo_kunmap(struct drm_bo_kmap_obj *map)
 574 {
 575         if (!map->virtual)
 576                 return;
 577
 578         switch (map->bo_kmap_type) {
 579         case bo_map_iomap:
 580                 iounmap(map->virtual);
 581                 break;
 582         case bo_map_vmap:
 583                 vunmap(map->virtual);
 584                 break;
 585         case bo_map_kmap:
 586                 kunmap(map->page);
 587                 break;
 588         case bo_map_premapped:
 589                 break;
 590         default:
 591                 BUG();
 592         }
 593         map->virtual = NULL;
 594         map->page = NULL;
 595 }
 596 EXPORT_SYMBOL(drm_bo_kunmap);
 597
 598 int drm_bo_pfn_prot(struct drm_buffer_object *bo,
 599                     unsigned long dst_offset,
 600                     unsigned long *pfn,
 601                     pgprot_t *prot)
 602 {
 603         struct drm_bo_mem_reg *mem = &bo->mem;
 604         struct drm_device *dev = bo->dev;
 605         unsigned long bus_offset;
 606         unsigned long bus_size;
 607         unsigned long bus_base;
 608         struct drm_mem_type_manager *man = &dev->bm.man[mem->mem_type];
 609         int ret;
 610
 611         ret = drm_bo_pci_offset(dev, mem, &bus_base, &bus_offset,
 612                                 &bus_size);
 613         if (ret)
 614                 return -EINVAL;
 615
 616         if (bus_size != 0)
 617                 *pfn = (bus_base + bus_offset + dst_offset) >> PAGE_SHIFT;
 618         else if (!bo->ttm)
 619                 return -EINVAL;
 620         else
 621                 *pfn = page_to_pfn(drm_ttm_get_page(bo->ttm, dst_offset >> PAGE_SHIFT));
 622
 623         *prot = (mem->flags & DRM_BO_FLAG_CACHED) ?
 624                 PAGE_KERNEL : drm_kernel_io_prot(man->drm_bus_maptype);
 625
 626         return 0;
 627 }
 628 EXPORT_SYMBOL(drm_bo_pfn_prot);
 629