Add support for non volatile variables

This adds (back) support for non volatile variables. Non volatile
variables are variables which are stored in the environment over
reboot. They are used in the same way as the global variables, but
with a 'nv' command and device. The variables are stored under
/env/nv/, one variable per file. Adding a nv variable automatically
adds a global variable with the same name. Changing a nv variable
also changes the same global variable, but not the other way round.
This allows for example to configure the username as:

nv user=sha; saveenv

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/globalvar.h b/include/globalvar.h
index 456e8cd1f8..56b23fdf22 100644
--- a/include/globalvar.h
+++ b/include/globalvar.h
@@ -72,6 +72,12 @@ static inline int globalvar_add_simple_ip(const char *name,
 
 	return 0;
 }
+
+int nvvar_load(void);
+void nvvar_print(void);
+int nvvar_add(const char *name, const char *value);
+int nvvar_remove(const char *name);
+
 #else
 static inline int globalvar_add_simple(const char *name, const char *value)
 {
@@ -116,6 +122,12 @@ static inline char *globalvar_get_match(const char *match, const char *separator
 }
 
 static inline void globalvar_set_match(const char *match, const char *val) {}
+
+static inline int nvvar_load(void)
+{
+	return 0;
+}
+
 #endif
 
 #endif /* __GLOBALVAR_H */