drm/ttm: add gem base object

Add drm_gem_object struct to ttm_buffer_object, so ttm objects are a gdm
object superclass.  Add a function to check whenever a given bo actually
uses the embedded drm_gem_object.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190805140119.7337-2-kraxel@redhat.com

include/drm/ttm/ttm_bo_api.h

@@ -31,6 +31,7 @@
 #ifndef _TTM_BO_API_H_
 #define _TTM_BO_API_H_
 
+#include <drm/drm_gem.h>
 #include <drm/drm_hashtab.h>
 #include <drm/drm_vma_manager.h>
 #include <linux/kref.h>
@@ -127,6 +128,7 @@ struct ttm_tt;
 /**
  * struct ttm_buffer_object
  *
+ * @base: drm_gem_object superclass data.
  * @bdev: Pointer to the buffer object device structure.
  * @type: The bo type.
  * @destroy: Destruction function. If NULL, kfree is used.
@@ -169,6 +171,8 @@ struct ttm_tt;
  */
 
 struct ttm_buffer_object {
+	struct drm_gem_object base;
+
 	/**
 	 * Members constant at init.
 	 */
@@ -768,4 +772,23 @@ int ttm_bo_swapout(struct ttm_bo_global *glob,
 			struct ttm_operation_ctx *ctx);
 void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
 int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo);
+
+/**
+ * ttm_bo_uses_embedded_gem_object - check if the given bo uses the
+ * embedded drm_gem_object.
+ *
+ * Most ttm drivers are using gem too, so the embedded
+ * ttm_buffer_object.base will be initialized by the driver (before
+ * calling ttm_bo_init).  It is also possible to use ttm without gem
+ * though (vmwgfx does that).
+ *
+ * This helper will figure whenever a given ttm bo is a gem object too
+ * or not.
+ *
+ * @bo: The bo to check.
+ */
+static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
+{
+	return bo->base.dev != NULL;
+}
 #endif