expo: Provide access to the current menu item

Add functions to allow a caller to find out the current menu item and to
select a different one.

Update the event handling so that an attempt to change the current item
(e.g. by pressing the up-arrow key) is reported to the caller, since
this may be used to cancel an autoboot timeout.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/expo.h b/include/expo.h
index f8d44c0..a2b093c 100644
--- a/include/expo.h
+++ b/include/expo.h
@@ -690,6 +690,26 @@
 int scene_menu_set_pointer(struct scene *scn, uint id, uint cur_item_id);
 
 /**
+ * scene_menu_select_item() - move the pointer/highlight to an item
+ *
+ * @scn: Scene to update
+ * @id: ID of menu object to update
+ * @sel_id: ID of the menuitem to select
+ * Return 0 on success, -ENOENT if there was no such item
+ */
+int scene_menu_select_item(struct scene *scn, uint id, uint sel_id);
+
+/**
+ * scene_menu_get_cur_item() - get the currently pointed-to item
+ *
+ * @scn: Scene to update
+ * @id: ID of menu object to update
+ * Return ID of the current item the menu is pointing to, -ENOENT if @id is not
+ * valid, 0 if no item is pointed to
+ */
+int scene_menu_get_cur_item(struct scene *scn, uint id);
+
+/**
  * scene_obj_get_hw() - Get width and height of an object in a scene
  *
  * @scn: Scene to check