1 files changed, 74 insertions, 0 deletions

diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 0a013ab3ae27..e95718fea355 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -661,6 +661,80 @@ bool sym_set_string_value(struct symbol *sym, const char *newval)
         return true;
 }
 
+/*
+ * Find the default value associated to a symbol.
+ * For tristate symbol handle the modules=n case
+ * in which case "m" becomes "y".
+ * If the symbol does not have any default then fallback
+ * to the fixed default values.
+ */
+const char *sym_get_string_default(struct symbol *sym)
+{
+        struct property *prop;
+        struct symbol *ds;
+        const char *str;
+        tristate val;
+
+        sym_calc_visibility(sym);
+        sym_calc_value(modules_sym);
+        val = symbol_no.curr.tri;
+        str = symbol_empty.curr.val;
+
+        /* If symbol has a default value look it up */
+        prop = sym_get_default_prop(sym);
+        if (prop != NULL) {
+                switch (sym->type) {
+                case S_BOOLEAN:
+                case S_TRISTATE:
+                        /* The visibility imay limit the value from yes => mod */
+                        val = EXPR_AND(expr_calc_value(prop->expr), prop->visible.tri);
+                        break;
+                default:
+                        /*
+                         * The following fails to handle the situation
+                         * where a default value is further limited by
+                         * the valid range.
+                         */
+                        ds = prop_get_symbol(prop);
+                        if (ds != NULL) {
+                                sym_calc_value(ds);
+                                str = (const char *)ds->curr.val;
+                        }
+                }
+        }
+
+        /* Handle select statements */
+        val = EXPR_OR(val, sym->rev_dep.tri);
+
+        /* transpose mod to yes if modules are not enabled */
+        if (val == mod)
+                if (!sym_is_choice_value(sym) && modules_sym->curr.tri == no)
+                        val = yes;
+
+        /* transpose mod to yes if type is bool */
+        if (sym->type == S_BOOLEAN && val == mod)
+                val = yes;
+
+        switch (sym->type) {
+        case S_BOOLEAN:
+        case S_TRISTATE:
+                switch (val) {
+                case no: return "n";
+                case mod: return "m";
+                case yes: return "y";
+                }
+        case S_INT:
+        case S_HEX:
+                return str;
+        case S_STRING:
+                return str;
+        case S_OTHER:
+        case S_UNKNOWN:
+                break;
+        }
+        return "";
+}
+
 const char *sym_get_string_value(struct symbol *sym)
 {
         tristate val;