xref: /openbmc/u-boot/doc/README.menu (revision 93322749) 
1/*
2 * Copyright 2010-2011 Calxeda, Inc.
3 *
4 * SPDX-License-Identifier:	GPL-2.0+
5 */
6
7U-boot provides a set of interfaces for creating and using simple, text
8based menus. Menus are displayed as lists of labeled entries on the
9console, and an entry can be selected by entering its label.
10
11To use the menu code, enable CONFIG_MENU, and include "menu.h" where
12the interfaces should be available.
13
14Menus are composed of items. Each item has a key used to identify it in
15the menu, and an opaque pointer to data controlled by the consumer.
16
17If you want to show a menu, instead starting the shell, define
18CONFIG_MENU_SHOW. You have to code the int menu_show(int bootdelay)
19function, which handle your menu. This function returns the remaining
20bootdelay.
21
22Interfaces
23----------
24#include "menu.h"
25
26/*
27 * Consumers of the menu interfaces will use a struct menu * as the
28 * handle for a menu. struct menu is only fully defined in menu.c,
29 * preventing consumers of the menu interfaces from accessing its
30 * contents directly.
31 */
32struct menu;
33
34/*
35 * NOTE: See comments in common/menu.c for more detailed documentation on
36 * these interfaces.
37 */
38
39/*
40 * menu_create() - Creates a menu handle with default settings
41 */
42struct menu *menu_create(char *title, int timeout, int prompt,
43				void (*item_data_print)(void *),
44				char *(*item_choice)(void *),
45				void *item_choice_data);
46
47/*
48 * menu_item_add() - Adds or replaces a menu item
49 */
50int menu_item_add(struct menu *m, char *item_key, void *item_data);
51
52/*
53 * menu_default_set() - Sets the default choice for the menu
54 */
55int menu_default_set(struct menu *m, char *item_key);
56
57/*
58 * menu_default_choice() - Set *choice to point to the default item's data
59 */
60int menu_default_choice(struct menu *m, void **choice);
61
62/*
63 * menu_get_choice() - Returns the user's selected menu entry, or the
64 * default if the menu is set to not prompt or the timeout expires.
65 */
66int menu_get_choice(struct menu *m, void **choice);
67
68/*
69 * menu_destroy() - frees the memory used by a menu and its items.
70 */
71int menu_destroy(struct menu *m);
72
73/*
74 * menu_display_statusline(struct menu *m);
75 * shows a statusline for every menu_display call.
76 */
77void menu_display_statusline(struct menu *m);
78
79Example Code
80------------
81This example creates a menu that always prompts, and allows the user
82to pick from a list of tools.  The item key and data are the same.
83
84#include "menu.h"
85
86char *tools[] = {
87	"Hammer",
88	"Screwdriver",
89	"Nail gun",
90	NULL
91};
92
93char *pick_a_tool(void)
94{
95	struct menu *m;
96	int i;
97	char *tool = NULL;
98
99	m = menu_create("Tools", 0, 1, NULL);
100
101	for(i = 0; tools[i]; i++) {
102		if (menu_item_add(m, tools[i], tools[i]) != 1) {
103			printf("failed to add item!");
104			menu_destroy(m);
105			return NULL;
106		}
107	}
108
109	if (menu_get_choice(m, (void **)&tool) != 1)
110		printf("Problem picking tool!\n");
111
112	menu_destroy(m);
113
114	return tool;
115}
116
117void caller(void)
118{
119	char *tool = pick_a_tool();
120
121	if (tool) {
122		printf("picked a tool: %s\n", tool);
123		use_tool(tool);
124	}
125}
126