kconfig: add an option to determine a menu's visibility

This option is aimed to add the possibility to control a menu's visibility
without adding dependency to the expression to all the submenu.

Signed-off-by: Arnaud Lacombe <[e-mail]>
Acked-by: Mauro Carvalho Chehab <[e-mail]>
Tested-by: Mauro Carvalho Chehab <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

scripts/kconfig/expr.h

···
 	struct menu *list;
 	struct symbol *sym;
 	struct property *prompt;
+	struct expr *visibility;
 	struct expr *dep;
 	unsigned int flags;
 	char *help;

scripts/kconfig/lkc.h

···
 void menu_add_entry(struct symbol *sym);
 void menu_end_entry(void);
 void menu_add_dep(struct expr *dep);
+void menu_add_visibility(struct expr *dep);
 struct property *menu_add_prop(enum prop_type type, char *prompt, struct expr *expr, struct expr *dep);
 struct property *menu_add_prompt(enum prop_type type, char *prompt, struct expr *dep);
 void menu_add_expr(enum prop_type type, struct expr *expr, struct expr *dep);

scripts/kconfig/menu.c

···
 	return menu_add_prop(type, prompt, NULL, dep);
 }
 
+void menu_add_visibility(struct expr *expr)
+{
+	current_entry->visibility = expr_alloc_and(current_entry->visibility,
+	    expr);
+}
+
 void menu_add_expr(enum prop_type type, struct expr *expr, struct expr *dep)
 {
 	menu_add_prop(type, NULL, expr, dep);
···
 
 	if (!menu->prompt)
 		return false;
+
+	if (menu->visibility) {
+		if (expr_calc_value(menu->visibility) == no)
+			return no;
+	}
 
 	sym = menu->sym;
 	if (sym) {

scripts/kconfig/zconf.gperf

···
 string,		T_TYPE,		TF_COMMAND, S_STRING
 select,		T_SELECT,	TF_COMMAND
 range,		T_RANGE,	TF_COMMAND
+visible,	T_VISIBLE,	TF_COMMAND
 option,		T_OPTION,	TF_COMMAND
 on,		T_ON,		TF_PARAM
 modules,	T_OPT_MODULES,	TF_OPTION

scripts/kconfig/zconf.y

···
 #define YYERROR_VERBOSE
 #endif
 %}
-%expect 28
+%expect 30
 
 %union
 {
···
 %token <id>T_DEFAULT
 %token <id>T_SELECT
 %token <id>T_RANGE
+%token <id>T_VISIBLE
 %token <id>T_OPTION
 %token <id>T_ON
 %token <string> T_WORD
···
 ;
 
 option_name:
-	T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_OPTIONAL | T_RANGE | T_DEFAULT
+	T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
 ;
 
 common_stmt:
···
 	printd(DEBUG_PARSE, "%s:%d:menu\n", zconf_curname(), zconf_lineno());
 };
 
-menu_entry: menu depends_list
+menu_entry: menu visibility_list depends_list
 {
 	$$ = menu_add_menu();
 };
···
 {
 	menu_add_dep($3);
 	printd(DEBUG_PARSE, "%s:%d:depends on\n", zconf_curname(), zconf_lineno());
+};
+
+/* visibility option */
+
+visibility_list:
+	  /* empty */
+	| visibility_list visible
+	| visibility_list T_EOL
+;
+
+visible: T_VISIBLE if_expr
+{
+	menu_add_visibility($2);
 };
 
 /* prompt statement */
···
 	case T_IF:		return "if";
 	case T_ENDIF:		return "endif";
 	case T_DEPENDS:		return "depends";
+	case T_VISIBLE:		return "visible";
 	}
 	return "<token>";
 }