drm/framebuffer: Add framebuffer debugfs file

Add debugfs file that dumps info about the framebuffers and its planes.
Also dump info about any connected gem object(s).

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171107191348.17555-5-noralf@tronnes.org

include/drm/drm_drv.h

@@ -39,6 +39,7 @@ struct drm_minor;
 struct dma_buf_attachment;
 struct drm_display_mode;
 struct drm_mode_create_dumb;
+struct drm_printer;
 
 /* driver capabilities and requirements mask */
 #define DRIVER_USE_AGP			0x1
@@ -428,6 +429,20 @@ struct drm_driver {
 	 */
 	void (*gem_close_object) (struct drm_gem_object *, struct drm_file *);
 
+	/**
+	 * @gem_print_info:
+	 *
+	 * If driver subclasses struct &drm_gem_object, it can implement this
+	 * optional hook for printing additional driver specific info.
+	 *
+	 * drm_printf_indent() should be used in the callback passing it the
+	 * indent argument.
+	 *
+	 * This callback is called from drm_gem_print_info().
+	 */
+	void (*gem_print_info)(struct drm_printer *p, unsigned int indent,
+			       const struct drm_gem_object *obj);
+
 	/**
 	 * @gem_create_object: constructor for gem objects
 	 *