/* * Copyright 2009 Jerome Glisse. * All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sub license, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE * USE OR OTHER DEALINGS IN THE SOFTWARE. * * The above copyright notice and this permission notice (including the * next paragraph) shall be included in all copies or substantial portions * of the Software. * */ /* * Authors: * Jerome Glisse * Thomas Hellstrom * Dave Airlie */ #include #include #include #include #include #include #include #include #include #include "radeon_reg.h" #include "radeon.h" #define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT) static int radeon_ttm_debugfs_init(struct radeon_device *rdev); static void radeon_ttm_debugfs_fini(struct radeon_device *rdev); static struct radeon_device *radeon_get_rdev(struct ttm_bo_device *bdev) { struct radeon_mman *mman; struct radeon_device *rdev; mman = container_of(bdev, struct radeon_mman, bdev); rdev = container_of(mman, struct radeon_device, mman); return rdev; } /* * Global memory. */ static int radeon_ttm_mem_global_init(struct drm_global_reference *ref) { return ttm_mem_global_init(ref->object); } static void radeon_ttm_mem_global_release(struct drm_global_reference *ref) { ttm_mem_global_release(ref->object); } static int radeon_ttm_global_init(struct radeon_device *rdev) { struct drm_global_reference *global_ref; int r; rdev->mman.mem_global_referenced = false; global_ref = &rdev->mman.mem_global_ref; global_ref->global_type = DRM_GLOBAL_TTM_MEM; global_ref->size = sizeof(struct ttm_mem_global); global_ref->init = &radeon_ttm_mem_global_init; global_ref->release = &radeon_ttm_mem_global_release; r = drm_global_item_ref(global_ref); if (r != 0) { DRM_ERROR("Failed setting up TTM memory accounting " "subsystem.\n"); return r; } rdev->mman.bo_global_ref.mem_glob = rdev->mman.mem_global_ref.object; global_ref = &rdev->mman.bo_global_ref.ref; global_ref->global_type = DRM_GLOBAL_TTM_BO; global_ref->size = sizeof(struct ttm_bo_global); global_ref->init = &ttm_bo_global_init; global_ref->release = &ttm_bo_global_release; r = drm_global_item_ref(global_ref); if (r != 0) { DRM_ERROR("Failed setting up TTM BO subsystem.\n"); drm_global_item_unref(&rdev->mman.mem_global_ref); return r; } rdev->mman.mem_global_referenced = true; return 0; } static int radeon_invalidate_caches(struct ttm_bo_device *bdev, uint32_t flags) { return 0; } static int radeon_init_mem_type(struct ttm_bo_device *bdev, uint32_t type, struct ttm_mem_type_manager *man) { struct radeon_device *rdev; rdev = radeon_get_rdev(bdev); switch (type) { case TTM_PL_SYSTEM: /* System memory */ man->flags = TTM_MEMTYPE_FLAG_MAPPABLE; man->available_caching = TTM_PL_MASK_CACHING; man->default_caching = TTM_PL_FLAG_CACHED; break; case TTM_PL_TT: man->func = &ttm_bo_manager_func; man->gpu_offset = rdev->mc.gtt_start; man->available_caching = TTM_PL_MASK_CACHING; man->default_caching = TTM_PL_FLAG_CACHED; man->flags = TTM_MEMTYPE_FLAG_MAPPABLE | TTM_MEMTYPE_FLAG_CMA; #if __OS_HAS_AGP if (rdev->flags & RADEON_IS_AGP) { if (!rdev->ddev->agp) { DRM_ERROR("AGP is not enabled for memory type %u\n", (unsigned)type); return -EINVAL; } if (!rdev->ddev->agp->cant_use_aperture) man->flags = TTM_MEMTYPE_FLAG_MAPPABLE; man->available_caching = TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_WC; man->default_caching = TTM_PL_FLAG_WC; } #endif break; case TTM_PL_VRAM: /* "On-card" video ram */ man->func = &ttm_bo_manager_func; man->gpu_offset = rdev->mc.vram_start; man->flags = TTM_MEMTYPE_FLAG_FIXED | TTM_MEMTYPE_FLAG_MAPPABLE; man->available_caching = TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_WC; man->default_caching = TTM_PL_FLAG_WC; break; default: DRM_ERROR("Unsupported memory type %u\n", (unsigned)type); return -EINVAL; } return 0; } static void radeon_evict_flags(struct ttm_buffer_object *bo, struct ttm_placement *placement) { struct radeon_bo *rbo; static u32 placements = TTM_PL_MASK_CACHING | TTM_PL_FLAG_SYSTEM; if (!radeon_ttm_bo_is_radeon_bo(bo)) { placement->fpfn = 0; placement->lpfn = 0; placement->placement = &placements; placement->busy_placement = &placements; placement->num_placement = 1; placement->num_busy_placement = 1; return; } rbo = container_of(bo, struct radeon_bo, tbo); switch (bo->mem.mem_type) { case TTM_PL_VRAM: if (rbo->rdev->ring[RADEON_RING_TYPE_GFX_INDEX].ready == false) radeon_ttm_placement_from_domain(rbo, RADEON_GEM_DOMAIN_CPU); else radeon_ttm_placement_from_domain(rbo, RADEON_GEM_DOMAIN_GTT); break; case TTM_PL_TT: default: radeon_ttm_placement_from_domain(rbo, RADEON_GEM_DOMAIN_CPU); } *placement = rbo->placement; } static int radeon_verify_access(struct ttm_buffer_object *bo, struct file *filp) { return 0; } static void radeon_move_null(struct ttm_buffer_object *bo, struct ttm_mem_reg *new_mem) { struct ttm_mem_reg *old_mem = &bo->mem; BUG_ON(old_mem->mm_node != NULL); *old_mem = *new_mem; new_mem->mm_node = NULL; } static int radeon_move_blit(struct ttm_buffer_object *bo, bool evict, bool no_wait_gpu, struct ttm_mem_reg *new_mem, struct ttm_mem_reg *old_mem) { struct radeon_device *rdev; uint64_t old_start, new_start; struct radeon_fence *fence; int r, ridx; rdev = radeon_get_rdev(bo->bdev); ridx = radeon_copy_ring_index(rdev); old_start = old_mem->start << PAGE_SHIFT; new_start = new_mem->start << PAGE_SHIFT; switch (old_mem->mem_type) { case TTM_PL_VRAM: old_start += rdev->mc.vram_start; break; case TTM_PL_TT: old_start += rdev->mc.gtt_start; break; default: DRM_ERROR("Unknown placement %d\n", old_mem->mem_type); return -EINVAL; } switch (new_mem->mem_type) { case TTM_PL_VRAM: new_start += rdev->mc.vram_start; break; case TTM_PL_TT: new_start += rdev->mc.gtt_start; break; default: DRM_ERROR("Unknown placement %d\n", old_mem->mem_type); return -EINVAL; } if (!rdev->ring[ridx].ready) { DRM_ERROR("Trying to move memory with ring turned off.\n"); return -EINVAL; } BUILD_BUG_ON((PAGE_SIZE % RADEON_GPU_PAGE_SIZE) != 0); /* sync other rings */ fence = bo->sync_obj; r = radeon_copy(rdev, old_start, new_start, new_mem->num_pages * (PAGE_SIZE / RADEON_GPU_PAGE_SIZE), /* GPU pages */ &fence); /* FIXME: handle copy error */ r = ttm_bo_move_accel_cleanup(bo, (void *)fence, evict, no_wait_gpu, new_mem); radeon_fence_unref(&fence); return r; } static int radeon_move_vram_ram(struct ttm_buffer_object *bo, bool evict, bool interruptible, bool no_wait_gpu, struct ttm_mem_reg *new_mem) { struct radeon_device *rdev; struct ttm_mem_reg *old_mem = &bo->mem; struct ttm_mem_reg tmp_mem; u32 placements; struct ttm_placement placement; int r; rdev = radeon_get_rdev(bo->bdev); tmp_mem = *new_mem; tmp_mem.mm_node = NULL; placement.fpfn = 0; placement.lpfn = 0; placement.num_placement = 1; placement.placement = &placements; placement.num_busy_placement = 1; placement.busy_placement = &placements; placements = TTM_PL_MASK_CACHING | TTM_PL_FLAG_TT; r = ttm_bo_mem_space(bo, &placement, &tmp_mem, interruptible, no_wait_gpu); if (unlikely(r)) { return r; } r = ttm_tt_set_placement_caching(bo->ttm, tmp_mem.placement); if (unlikely(r)) { goto out_cleanup; } r = ttm_tt_bind(bo->ttm, &tmp_mem); if (unlikely(r)) { goto out_cleanup; } r = radeon_move_blit(bo, true, no_wait_gpu, &tmp_mem, old_mem); if (unlikely(r)) { goto out_cleanup; } r = ttm_bo_move_ttm(bo, true, no_wait_gpu, new_mem); out_cleanup: ttm_bo_mem_put(bo, &tmp_mem); return r; } static int radeon_move_ram_vram(struct ttm_buffer_object *bo, bool evict, bool interruptible, bool no_wait_gpu, struct ttm_mem_reg *new_mem) { struct radeon_device *rdev; struct ttm_mem_reg *old_mem = &bo->mem; struct ttm_mem_reg tmp_mem; struct ttm_placement placement; u32 placements; int r; rdev = radeon_get_rdev(bo->bdev); tmp_mem = *new_mem; tmp_mem.mm_node = NULL; placement.fpfn = 0; placement.lpfn = 0; placement.num_placement = 1; placement.placement = &placements; placement.num_busy_placement = 1; placement.busy_placement = &placements; placements = TTM_PL_MASK_CACHING | TTM_PL_FLAG_TT; r = ttm_bo_mem_space(bo, &placement, &tmp_mem, interruptible, no_wait_gpu); if (unlikely(r)) { return r; } r = ttm_bo_move_ttm(bo, true, no_wait_gpu, &tmp_mem); if (unlikely(r)) { goto out_cleanup; } r = radeon_move_blit(bo, true, no_wait_gpu, new_mem, old_mem); if (unlikely(r)) { goto out_cleanup; } out_cleanup: ttm_bo_mem_put(bo, &tmp_mem); return r; } static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict, bool interruptible, bool no_wait_gpu, struct ttm_mem_reg *new_mem) { struct radeon_device *rdev; struct ttm_mem_reg *old_mem = &bo->mem; int r; rdev = radeon_get_rdev(bo->bdev); if (old_mem->mem_type == TTM_PL_SYSTEM && bo->ttm == NULL) { radeon_move_null(bo, new_mem); return 0; } if ((old_mem->mem_type == TTM_PL_TT && new_mem->mem_type == TTM_PL_SYSTEM) || (old_mem->mem_type == TTM_PL_SYSTEM && new_mem->mem_type == TTM_PL_TT)) { /* bind is enough */ radeon_move_null(bo, new_mem); return 0; } if (!rdev->ring[radeon_copy_ring_index(rdev)].ready || rdev->asic->copy.copy == NULL) { /* use memcpy */ goto memcpy; } if (old_mem->mem_type == TTM_PL_VRAM && new_mem->mem_type == TTM_PL_SYSTEM) { r = radeon_move_vram_ram(bo, evict, interruptible, no_wait_gpu, new_mem); } else if (old_mem->mem_type == TTM_PL_SYSTEM && new_mem->mem_type == TTM_PL_VRAM) { r = radeon_move_ram_vram(bo, evict, interruptible, no_wait_gpu, new_mem); } else { r = radeon_move_blit(bo, evict, no_wait_gpu, new_mem, old_mem); } if (r) { memcpy: r = ttm_bo_move_memcpy(bo, evict, no_wait_gpu, new_mem); if (r) { return r; } } /* update statistics */ // atomic64_add((u64)bo->num_pages << PAGE_SHIFT, &rdev->num_bytes_moved); return 0; } static int radeon_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem) { struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type]; struct radeon_device *rdev = radeon_get_rdev(bdev); mem->bus.addr = NULL; mem->bus.offset = 0; mem->bus.size = mem->num_pages << PAGE_SHIFT; mem->bus.base = 0; mem->bus.is_iomem = false; if (!(man->flags & TTM_MEMTYPE_FLAG_MAPPABLE)) return -EINVAL; switch (mem->mem_type) { case TTM_PL_SYSTEM: /* system memory */ return 0; case TTM_PL_TT: #if __OS_HAS_AGP if (rdev->flags & RADEON_IS_AGP) { /* RADEON_IS_AGP is set only if AGP is active */ mem->bus.offset = mem->start << PAGE_SHIFT; mem->bus.base = rdev->mc.agp_base; mem->bus.is_iomem = !rdev->ddev->agp->cant_use_aperture; } #endif break; case TTM_PL_VRAM: mem->bus.offset = mem->start << PAGE_SHIFT; /* check if it's visible */ if ((mem->bus.offset + mem->bus.size) > rdev->mc.visible_vram_size) return -EINVAL; mem->bus.base = rdev->mc.aper_base; mem->bus.is_iomem = true; #ifdef __alpha__ /* * Alpha: use bus.addr to hold the ioremap() return, * so we can modify bus.base below. */ if (mem->placement & TTM_PL_FLAG_WC) mem->bus.addr = ioremap_wc(mem->bus.base + mem->bus.offset, mem->bus.size); else mem->bus.addr = ioremap_nocache(mem->bus.base + mem->bus.offset, mem->bus.size); /* * Alpha: Use just the bus offset plus * the hose/domain memory base for bus.base. * It then can be used to build PTEs for VRAM * access, as done in ttm_bo_vm_fault(). */ mem->bus.base = (mem->bus.base & 0x0ffffffffUL) + rdev->ddev->hose->dense_mem_base; #endif break; default: return -EINVAL; } return 0; } static void radeon_ttm_io_mem_free(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem) { } static int radeon_sync_obj_wait(void *sync_obj, bool lazy, bool interruptible) { return radeon_fence_wait((struct radeon_fence *)sync_obj, interruptible); } static int radeon_sync_obj_flush(void *sync_obj) { return 0; } static void radeon_sync_obj_unref(void **sync_obj) { radeon_fence_unref((struct radeon_fence **)sync_obj); } static void *radeon_sync_obj_ref(void *sync_obj) { return radeon_fence_ref((struct radeon_fence *)sync_obj); } static bool radeon_sync_obj_signaled(void *sync_obj) { return radeon_fence_signaled((struct radeon_fence *)sync_obj); } /* * TTM backend functions. */ struct radeon_ttm_tt { struct ttm_dma_tt ttm; struct radeon_device *rdev; u64 offset; }; static int radeon_ttm_backend_bind(struct ttm_tt *ttm, struct ttm_mem_reg *bo_mem) { struct radeon_ttm_tt *gtt = (void*)ttm; uint32_t flags = RADEON_GART_PAGE_VALID | RADEON_GART_PAGE_READ | RADEON_GART_PAGE_WRITE; int r; gtt->offset = (unsigned long)(bo_mem->start << PAGE_SHIFT); if (!ttm->num_pages) { WARN(1, "nothing to bind %lu pages for mreg %p back %p!\n", ttm->num_pages, bo_mem, ttm); } if (ttm->caching_state == tt_cached) flags |= RADEON_GART_PAGE_SNOOP; r = radeon_gart_bind(gtt->rdev, gtt->offset, ttm->num_pages, ttm->pages, gtt->ttm.dma_address, flags); if (r) { DRM_ERROR("failed to bind %lu pages at 0x%08X\n", ttm->num_pages, (unsigned)gtt->offset); return r; } return 0; } static int radeon_ttm_backend_unbind(struct ttm_tt *ttm) { struct radeon_ttm_tt *gtt = (void *)ttm; radeon_gart_unbind(gtt->rdev, gtt->offset, ttm->num_pages); return 0; } static void radeon_ttm_backend_destroy(struct ttm_tt *ttm) { struct radeon_ttm_tt *gtt = (void *)ttm; // ttm_dma_tt_fini(>t->ttm); kfree(gtt); } static struct ttm_backend_func radeon_backend_func = { .bind = &radeon_ttm_backend_bind, .unbind = &radeon_ttm_backend_unbind, .destroy = &radeon_ttm_backend_destroy, }; static struct ttm_tt *radeon_ttm_tt_create(struct ttm_bo_device *bdev, unsigned long size, uint32_t page_flags, struct page *dummy_read_page) { struct radeon_device *rdev; struct radeon_ttm_tt *gtt; rdev = radeon_get_rdev(bdev); #if __OS_HAS_AGP if (rdev->flags & RADEON_IS_AGP) { return ttm_agp_tt_create(bdev, rdev->ddev->agp->bridge, size, page_flags, dummy_read_page); } #endif gtt = kzalloc(sizeof(struct radeon_ttm_tt), GFP_KERNEL); if (gtt == NULL) { return NULL; } gtt->ttm.ttm.func = &radeon_backend_func; gtt->rdev = rdev; if (ttm_dma_tt_init(>t->ttm, bdev, size, page_flags, dummy_read_page)) { kfree(gtt); return NULL; } return >t->ttm.ttm; } static int radeon_ttm_tt_populate(struct ttm_tt *ttm) { struct radeon_device *rdev; struct radeon_ttm_tt *gtt = (void *)ttm; unsigned i; int r; bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG); if (ttm->state != tt_unpopulated) return 0; if (slave && ttm->sg) { drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages, gtt->ttm.dma_address, ttm->num_pages); ttm->state = tt_unbound; return 0; } rdev = radeon_get_rdev(ttm->bdev); #if __OS_HAS_AGP if (rdev->flags & RADEON_IS_AGP) { return ttm_agp_tt_populate(ttm); } #endif #ifdef CONFIG_SWIOTLB if (swiotlb_nr_tbl()) { return ttm_dma_populate(>t->ttm, rdev->dev); } #endif r = ttm_pool_populate(ttm); if (r) { return r; } for (i = 0; i < ttm->num_pages; i++) { gtt->ttm.dma_address[i] = pci_map_page(rdev->pdev, ttm->pages[i], 0, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL); } return 0; } static void radeon_ttm_tt_unpopulate(struct ttm_tt *ttm) { struct radeon_device *rdev; struct radeon_ttm_tt *gtt = (void *)ttm; unsigned i; bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG); if (slave) return; rdev = radeon_get_rdev(ttm->bdev); #if __OS_HAS_AGP if (rdev->flags & RADEON_IS_AGP) { ttm_agp_tt_unpopulate(ttm); return; } #endif #ifdef CONFIG_SWIOTLB if (swiotlb_nr_tbl()) { ttm_dma_unpopulate(>t->ttm, rdev->dev); return; } #endif ttm_pool_unpopulate(ttm); } static struct ttm_bo_driver radeon_bo_driver = { .ttm_tt_create = &radeon_ttm_tt_create, .ttm_tt_populate = &radeon_ttm_tt_populate, .ttm_tt_unpopulate = &radeon_ttm_tt_unpopulate, .invalidate_caches = &radeon_invalidate_caches, .init_mem_type = &radeon_init_mem_type, .evict_flags = &radeon_evict_flags, .move = &radeon_bo_move, .verify_access = &radeon_verify_access, .sync_obj_signaled = &radeon_sync_obj_signaled, .sync_obj_wait = &radeon_sync_obj_wait, .sync_obj_flush = &radeon_sync_obj_flush, .sync_obj_unref = &radeon_sync_obj_unref, .sync_obj_ref = &radeon_sync_obj_ref, .move_notify = &radeon_bo_move_notify, // .fault_reserve_notify = &radeon_bo_fault_reserve_notify, .io_mem_reserve = &radeon_ttm_io_mem_reserve, .io_mem_free = &radeon_ttm_io_mem_free, }; int radeon_ttm_init(struct radeon_device *rdev) { int r; r = radeon_ttm_global_init(rdev); if (r) { return r; } /* No others user of address space so set it to 0 */ r = ttm_bo_device_init(&rdev->mman.bdev, rdev->mman.bo_global_ref.ref.object, &radeon_bo_driver, NULL, DRM_FILE_PAGE_OFFSET, rdev->need_dma32); if (r) { DRM_ERROR("failed initializing buffer object driver(%d).\n", r); return r; } rdev->mman.initialized = true; r = ttm_bo_init_mm(&rdev->mman.bdev, TTM_PL_VRAM, rdev->mc.real_vram_size >> PAGE_SHIFT); if (r) { DRM_ERROR("Failed initializing VRAM heap.\n"); return r; } /* Change the size here instead of the init above so only lpfn is affected */ radeon_ttm_set_active_vram_size(rdev, rdev->mc.visible_vram_size); r = radeon_bo_create(rdev, 16*1024*1024, PAGE_SIZE, true, RADEON_GEM_DOMAIN_VRAM, 0, NULL, &rdev->stollen_vga_memory); if (r) { return r; } r = radeon_bo_reserve(rdev->stollen_vga_memory, false); if (r) return r; r = radeon_bo_pin(rdev->stollen_vga_memory, RADEON_GEM_DOMAIN_VRAM, NULL); radeon_bo_unreserve(rdev->stollen_vga_memory); if (r) { radeon_bo_unref(&rdev->stollen_vga_memory); return r; } DRM_INFO("radeon: %uM of VRAM memory ready\n", (unsigned) (rdev->mc.real_vram_size / (1024 * 1024))); r = ttm_bo_init_mm(&rdev->mman.bdev, TTM_PL_TT, rdev->mc.gtt_size >> PAGE_SHIFT); if (r) { DRM_ERROR("Failed initializing GTT heap.\n"); return r; } DRM_INFO("radeon: %uM of GTT memory ready.\n", (unsigned)(rdev->mc.gtt_size / (1024 * 1024))); return 0; } /* this should only be called at bootup or when userspace * isn't running */ void radeon_ttm_set_active_vram_size(struct radeon_device *rdev, u64 size) { struct ttm_mem_type_manager *man; if (!rdev->mman.initialized) return; man = &rdev->mman.bdev.man[TTM_PL_VRAM]; /* this just adjusts TTM size idea, which sets lpfn to the correct value */ man->size = size >> PAGE_SHIFT; } static struct vm_operations_struct radeon_ttm_vm_ops; static const struct vm_operations_struct *ttm_vm_ops = NULL; #if 0 radeon_bo_init { <6>[drm] Detected VRAM RAM=1024M, BAR=256M <6>[drm] RAM width 128bits DDR radeon_ttm_init { radeon_ttm_global_init { radeon_ttm_mem_global_init ttm_bo_global_init } ttm_bo_device_init { ttm_bo_init_mm { radeon_init_mem_type }; } ttm_bo_init_mm { radeon_init_mem_type ttm_bo_man_init } <6>[drm] radeon: 1024M of VRAM memory ready ttm_bo_init_mm { radeon_init_mem_type ttm_bo_man_init } <6>[drm] radeon: 512M of GTT memory ready. } }; #endif int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages, dma_addr_t *addrs, int max_pages) { unsigned count; struct scatterlist *sg; struct page *page; u32 len; int pg_index; dma_addr_t addr; pg_index = 0; for_each_sg(sgt->sgl, sg, sgt->nents, count) { len = sg->length; page = sg_page(sg); addr = sg_dma_address(sg); while (len > 0) { if (WARN_ON(pg_index >= max_pages)) return -1; pages[pg_index] = page; if (addrs) addrs[pg_index] = addr; page++; addr += PAGE_SIZE; len -= PAGE_SIZE; pg_index++; } } return 0; }