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>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
index 5a72ed9..cc72435 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
@@ -139,85 +139,61 @@
 	.busy_placement = gmr_vram_placement_flags
 };
 
-struct vmw_ttm_backend {
-	struct ttm_backend backend;
-	struct page **pages;
-	unsigned long num_pages;
+struct vmw_ttm_tt {
+	struct ttm_tt ttm;
 	struct vmw_private *dev_priv;
 	int gmr_id;
 };
 
-static int vmw_ttm_populate(struct ttm_backend *backend,
-			    unsigned long num_pages, struct page **pages,
-			    struct page *dummy_read_page,
-			    dma_addr_t *dma_addrs)
+static int vmw_ttm_bind(struct ttm_tt *ttm, struct ttm_mem_reg *bo_mem)
 {
-	struct vmw_ttm_backend *vmw_be =
-	    container_of(backend, struct vmw_ttm_backend, backend);
-
-	vmw_be->pages = pages;
-	vmw_be->num_pages = num_pages;
-
-	return 0;
-}
-
-static int vmw_ttm_bind(struct ttm_backend *backend, struct ttm_mem_reg *bo_mem)
-{
-	struct vmw_ttm_backend *vmw_be =
-	    container_of(backend, struct vmw_ttm_backend, backend);
+	struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
 
 	vmw_be->gmr_id = bo_mem->start;
 
-	return vmw_gmr_bind(vmw_be->dev_priv, vmw_be->pages,
-			    vmw_be->num_pages, vmw_be->gmr_id);
+	return vmw_gmr_bind(vmw_be->dev_priv, ttm->pages,
+			    ttm->num_pages, vmw_be->gmr_id);
 }
 
-static int vmw_ttm_unbind(struct ttm_backend *backend)
+static int vmw_ttm_unbind(struct ttm_tt *ttm)
 {
-	struct vmw_ttm_backend *vmw_be =
-	    container_of(backend, struct vmw_ttm_backend, backend);
+	struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
 
 	vmw_gmr_unbind(vmw_be->dev_priv, vmw_be->gmr_id);
 	return 0;
 }
 
-static void vmw_ttm_clear(struct ttm_backend *backend)
+static void vmw_ttm_destroy(struct ttm_tt *ttm)
 {
-	struct vmw_ttm_backend *vmw_be =
-		container_of(backend, struct vmw_ttm_backend, backend);
-
-	vmw_be->pages = NULL;
-	vmw_be->num_pages = 0;
-}
-
-static void vmw_ttm_destroy(struct ttm_backend *backend)
-{
-	struct vmw_ttm_backend *vmw_be =
-	    container_of(backend, struct vmw_ttm_backend, backend);
+	struct vmw_ttm_tt *vmw_be = container_of(ttm, struct vmw_ttm_tt, ttm);
 
 	kfree(vmw_be);
 }
 
 static struct ttm_backend_func vmw_ttm_func = {
-	.populate = vmw_ttm_populate,
-	.clear = vmw_ttm_clear,
 	.bind = vmw_ttm_bind,
 	.unbind = vmw_ttm_unbind,
 	.destroy = vmw_ttm_destroy,
 };
 
-struct ttm_backend *vmw_ttm_backend_init(struct ttm_bo_device *bdev)
+struct ttm_tt *vmw_ttm_tt_create(struct ttm_bo_device *bdev,
+				 unsigned long size, uint32_t page_flags,
+				 struct page *dummy_read_page)
 {
-	struct vmw_ttm_backend *vmw_be;
+	struct vmw_ttm_tt *vmw_be;
 
 	vmw_be = kmalloc(sizeof(*vmw_be), GFP_KERNEL);
 	if (!vmw_be)
 		return NULL;
 
-	vmw_be->backend.func = &vmw_ttm_func;
+	vmw_be->ttm.func = &vmw_ttm_func;
 	vmw_be->dev_priv = container_of(bdev, struct vmw_private, bdev);
 
-	return &vmw_be->backend;
+	if (ttm_tt_init(&vmw_be->ttm, bdev, size, page_flags, dummy_read_page)) {
+		return NULL;
+	}
+
+	return &vmw_be->ttm;
 }
 
 int vmw_invalidate_caches(struct ttm_bo_device *bdev, uint32_t flags)
@@ -357,7 +333,7 @@
 }
 
 struct ttm_bo_driver vmw_bo_driver = {
-	.create_ttm_backend_entry = vmw_ttm_backend_init,
+	.ttm_tt_create = &vmw_ttm_tt_create,
 	.invalidate_caches = vmw_invalidate_caches,
 	.init_mem_type = vmw_init_mem_type,
 	.evict_flags = vmw_evict_flags,