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>

4 files changed, 107 insertions, 3 deletions

diff --git a/commands/Kconfig b/commands/Kconfig
index bef58473a5..cf32548725 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -674,6 +674,20 @@ endmenu
 
 menu "Environment"
 
+config CMD_NV
+	select GLOBALVAR
+	tristate
+	prompt "nv"
+	help
+	  create, set or remove non volatile variables.
+
+	  Usage: nv [-r] VAR[=VALUE]
+
+	  Add a new config non volatile named VAR, optionally set to VALUE.
+
+	  Options:
+		-r	remove a non volatile variable
+
 config CMD_EXPORT
 	depends on ENVIRONMENT_VARIABLES
 	tristate
diff --git a/commands/Makefile b/commands/Makefile
index be174969b0..b4fc3d363e 100644
--- a/commands/Makefile
+++ b/commands/Makefile
@@ -107,3 +107,4 @@ obj-$(CONFIG_CMD_HWCLOCK)	+= hwclock.o
 obj-$(CONFIG_CMD_USBGADGET)	+= usbgadget.o
 obj-$(CONFIG_CMD_FIRMWARELOAD)	+= firmwareload.o
 obj-$(CONFIG_CMD_CMP)		+= cmp.o
+obj-$(CONFIG_CMD_NV)		+= nv.o
diff --git a/commands/loadenv.c b/commands/loadenv.c
index 8b15af49df..91ce5e707c 100644
--- a/commands/loadenv.c
+++ b/commands/loadenv.c
@@ -27,12 +27,13 @@
 #include <errno.h>
 #include <fs.h>
 #include <malloc.h>
+#include <globalvar.h>
 
 static int do_loadenv(int argc, char *argv[])
 {
 	char *filename = NULL, *dirname;
 	unsigned flags = 0;
-	int opt;
+	int opt, ret;
 	int scrub = 0;
 	int defaultenv = 0;
 
@@ -97,9 +98,13 @@ static int do_loadenv(int argc, char *argv[])
 	printf("loading environment from %s\n", defaultenv ? "defaultenv" : filename);
 
 	if (defaultenv)
-		return defaultenv_load(dirname, flags);
+		ret = defaultenv_load(dirname, flags);
 	else
-		return envfs_load(filename, dirname, flags);
+		ret = envfs_load(filename, dirname, flags);
+
+	nvvar_load();
+
+	return ret;
 }
 
 BAREBOX_CMD_HELP_START(loadenv)
diff --git a/commands/nv.c b/commands/nv.c
new file mode 100644
index 0000000000..8cebb856f4
--- /dev/null
+++ b/commands/nv.c
@@ -0,0 +1,84 @@
+/*
+ * nv.c - non volatile shell variables
+ *
+ * Copyright (c) 2014 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <common.h>
+#include <malloc.h>
+#include <command.h>
+#include <globalvar.h>
+#include <environment.h>
+#include <getopt.h>
+
+static int do_nv(int argc, char *argv[])
+{
+	int opt;
+	int do_remove = 0;
+	int ret;
+	char *value;
+
+	while ((opt = getopt(argc, argv, "r")) > 0) {
+		switch (opt) {
+		case 'r':
+			do_remove = 1;
+			break;
+		default:
+			return COMMAND_ERROR_USAGE;
+		}
+	}
+
+	if (argc == optind) {
+		nvvar_print();
+		return 0;
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	if (argc != 1)
+		return COMMAND_ERROR_USAGE;
+
+	value = strchr(argv[0], '=');
+	if (value) {
+		*value = 0;
+		value++;
+	}
+
+	if (do_remove)
+		ret = nvvar_remove(argv[0]);
+	else
+		ret = nvvar_add(argv[0], value);
+
+	return ret;
+}
+
+BAREBOX_CMD_HELP_START(nv)
+BAREBOX_CMD_HELP_TEXT("Add a new non volatile variable named VAR, optionally set to VALUE.")
+BAREBOX_CMD_HELP_TEXT("non volatile variables are persistent variables that overwrite the")
+BAREBOX_CMD_HELP_TEXT("global variables of the same name. Their value is saved with")
+BAREBOX_CMD_HELP_TEXT("'saveenv'.")
+BAREBOX_CMD_HELP_TEXT("")
+BAREBOX_CMD_HELP_TEXT("Options:")
+BAREBOX_CMD_HELP_OPT("-r", "remove a non volatile variable")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(nv)
+	.cmd		= do_nv,
+	BAREBOX_CMD_DESC("create or set non volatile variables")
+	BAREBOX_CMD_OPTS("[-r] VAR[=VALUE]")
+	BAREBOX_CMD_GROUP(CMD_GRP_ENV)
+	BAREBOX_CMD_HELP(cmd_nv_help)
+BAREBOX_CMD_END