kconfig: environment symbol support

Add the possibility to import a value from the environment into kconfig
via the option syntax. Beside flexibility this has the advantage
providing proper dependencies.
Documented the options syntax.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index b6f922c77e0b..9d4cba1c001d 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -106,7 +106,8 @@ struct symbol {
 #define SYMBOL_HASHMASK         0xff
 
 enum prop_type {
-        P_UNKNOWN, P_PROMPT, P_COMMENT, P_MENU, P_DEFAULT, P_CHOICE, P_SELECT, P_RANGE
+        P_UNKNOWN, P_PROMPT, P_COMMENT, P_MENU, P_DEFAULT, P_CHOICE,
+        P_SELECT, P_RANGE, P_ENV
 };
 
 struct property {