Merge branch '2022-01-16-bootstd-updates'

To quote the author:
So far standard boot lacks a boot menu, although it is possible to create
a rudimentary one using the existing 'bootmenu' command.

Even then, this text-based menu offer only basic functionality and does
not take full advantage of the displays which are common on many devices.

This series provides a 'bootflow menu' command which allows the user to
select from the available bootflows. An attempt is made to show the name
of the available operating systems, by reading more information into the
bootflow. A logo can be read also, where supported, so that this can be
presented to the user when an option is highlighted.

Full use is made of TrueType fonts, if enabled. For cases where only a
serial console is available, it falls back to a simple text-based menu.

All of this is implementing using a new 'expo' construct, a collection of
scenes (like menu screens) which can be navigated by the user to view
information and select options. This is fairly general and should be able
to cope with a wider array of use cases, with less hacking of the menu
code, such as is currently needed for CMD_BOOTEFI_BOOTMGR.

Of course it would be possible to enhance the existing menu rather than
creating a new setup. Instead it seems better to make the existing menu
use expo, if code space permits. It avoids the event-loop problem and
should be more extensible, given its loosely coupled components and use of
IDs instead of pointers. Further motivation is provided in the
documentation.

For now the CLI keypress-decoding code is split out to be used by the new
menu. The key codes defined by menu.h are reused also.

This is of course just a starting point. Some ideas for future work are
included in the documentation.

1 files changed, 123 insertions, 0 deletions

diff --git a/boot/scene_internal.h b/boot/scene_internal.h
new file mode 100644
index 00000000000..e8fd765811e
--- /dev/null
+++ b/boot/scene_internal.h
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Internal header file for scenes
+ *
+ * Copyright 2022 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __SCENE_INTERNAL_H
+#define __SCENE_INTERNAL_H
+
+/**
+ * expo_lookup_scene_id() - Look up a scene ID
+ *
+ * @exp: Expo to use
+ * @id: scene ID to look up
+ * Returns: Scene for that ID, or NULL if none
+ */
+struct scene *expo_lookup_scene_id(struct expo *exp, uint scene_id);
+
+/**
+ * resolve_id() - Automatically allocate an ID if needed
+ *
+ * @exp: Expo to use
+ * @id: ID to use, or 0 to auto-allocate one
+ * @return: Either @id, or the auto-allocated ID
+ */
+uint resolve_id(struct expo *exp, uint id);
+
+/**
+ * scene_obj_find() - Find an object in a scene
+ *
+ * Note that @type is used to restrict the search when the object type is known.
+ * If any type is acceptable, set @type to SCENEOBJT_NONE
+ *
+ * @scn: Scene to search
+ * @id: ID of object to find
+ * @type: Type of the object, or SCENEOBJT_NONE to match any type
+ */
+void *scene_obj_find(struct scene *scn, uint id, enum scene_obj_t type);
+
+/**
+ * scene_obj_add() - Add a new object to a scene
+ *
+ * @scn: Scene to update
+ * @name: Name to use (this is allocated by this call)
+ * @id: ID to use for the new object (0 to allocate one)
+ * @type: Type of object to add
+ * @size: Size to allocate for the object, in bytes
+ * @objp: Returns a pointer to the new object (must not be NULL)
+ * Returns: ID number for the object (generally @id), or -ve on error
+ */
+int scene_obj_add(struct scene *scn, const char *name, uint id,
+		  enum scene_obj_t type, uint size, struct scene_obj **objp);
+
+/**
+ * scene_menu_arrange() - Set the position of things in the menu
+ *
+ * This updates any items associated with a menu to make sure they are
+ * positioned correctly relative to the menu. It also selects the first item
+ * if not already done
+ *
+ * @scn: Scene to update
+ * @menu: Menu to process
+ */
+int scene_menu_arrange(struct scene *scn, struct scene_obj_menu *menu);
+
+/**
+ * scene_menu_send_key() - Send a key to a menu for processing
+ *
+ * @scn: Scene to use
+ * @menu: Menu to use
+ * @key: Key code to send (KEY_...)
+ * @event: Place to put any event which is generated by the key
+ * @return 0 if OK, -ENOTTY if there is no current menu item, other -ve on other
+ *	error
+ */
+int scene_menu_send_key(struct scene *scn, struct scene_obj_menu *menu, int key,
+			struct expo_action *event);
+
+/**
+ * scene_menu_destroy() - Destroy a menu in a scene
+ *
+ * @scn: Scene to destroy
+ */
+void scene_menu_destroy(struct scene_obj_menu *menu);
+
+/**
+ * scene_menu_display() - Display a menu as text
+ *
+ * @menu: Menu to display
+ * @return 0 if OK, -ENOENT if @id is invalid
+ */
+int scene_menu_display(struct scene_obj_menu *menu);
+
+/**
+ * scene_destroy() - Destroy a scene and all its memory
+ *
+ * @scn: Scene to destroy
+ */
+void scene_destroy(struct scene *scn);
+
+/**
+ * scene_render() - Render a scene
+ *
+ * This is called from expo_render()
+ *
+ * @scn: Scene to render
+ * Returns: 0 if OK, -ve on error
+ */
+int scene_render(struct scene *scn);
+
+/**
+ * scene_send_key() - set a keypress to a scene
+ *
+ * @scn: Scene to receive the key
+ * @key: Key to send (KEYCODE_UP)
+ * @event: Returns resulting event from this keypress
+ * Returns: 0 if OK, -ve on error
+ */
+int scene_send_key(struct scene *scn, int key, struct expo_action *event);
+
+#endif /* __SCENE_INTERNAL_H */