drm/ttm: merge ttm_backend and ttm_tt V5

ttm_backend will only exist with a ttm_tt, and ttm_tt
will only be of interest when bound to a backend. Merge them
to avoid code and data duplication.

V2 Rebase on top of memory accounting overhaul
V3 Rebase on top of more memory accounting changes
V4 Rebase on top of no memory account changes (where/when is my
   delorean when i need it ?)
V5 make sure ttm is unbound before destroying, change commit
   message on suggestion from Tormod Volden

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -343,20 +343,24 @@ nouveau_bo_wr32(struct nouveau_bo *nvbo, unsigned index, u32 val)
 		*mem = val;
 }
 
-static struct ttm_backend *
-nouveau_bo_create_ttm_backend_entry(struct ttm_bo_device *bdev)
+static struct ttm_tt *
+nouveau_ttm_tt_create(struct ttm_bo_device *bdev,
+		      unsigned long size, uint32_t page_flags,
+		      struct page *dummy_read_page)
 {
 	struct drm_nouveau_private *dev_priv = nouveau_bdev(bdev);
 	struct drm_device *dev = dev_priv->dev;
 
 	switch (dev_priv->gart_info.type) {
 #if __OS_HAS_AGP
 	case NOUVEAU_GART_AGP:
-		return ttm_agp_backend_init(bdev, dev->agp->bridge);
+		return ttm_agp_tt_create(bdev, dev->agp->bridge,
+					 size, page_flags, dummy_read_page);
 #endif
 	case NOUVEAU_GART_PDMA:
 	case NOUVEAU_GART_HW:
-		return nouveau_sgdma_init_ttm(dev);
+		return nouveau_sgdma_create_ttm(bdev, size, page_flags,
+						dummy_read_page);
 	default:
 		NV_ERROR(dev, "Unknown GART type %d\n",
 			 dev_priv->gart_info.type);
@@ -1045,7 +1049,7 @@ nouveau_bo_fence(struct nouveau_bo *nvbo, struct nouveau_fence *fence)
 }
 
 struct ttm_bo_driver nouveau_bo_driver = {
-	.create_ttm_backend_entry = nouveau_bo_create_ttm_backend_entry,
+	.ttm_tt_create = &nouveau_ttm_tt_create,
 	.invalidate_caches = nouveau_bo_invalidate_caches,
 	.init_mem_type = nouveau_bo_init_mem_type,
 	.evict_flags = nouveau_bo_evict_flags,

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -1000,7 +1000,10 @@ extern int nouveau_sgdma_init(struct drm_device *);
 extern void nouveau_sgdma_takedown(struct drm_device *);
 extern uint32_t nouveau_sgdma_get_physical(struct drm_device *,
 					   uint32_t offset);
-extern struct ttm_backend *nouveau_sgdma_init_ttm(struct drm_device *);
+extern struct ttm_tt *nouveau_sgdma_create_ttm(struct ttm_bo_device *bdev,
+					       unsigned long size,
+					       uint32_t page_flags,
+					       struct page *dummy_read_page);
 
 /* nouveau_debugfs.c */
 #if defined(CONFIG_DRM_NOUVEAU_DEBUG)