ENGR00174841 [U-Boot]Add a command to erase any pre-saved environment

A "destroyenv" command is provided to erase any pre-save environment in the
boot storage. The command simply add 1 to the CRC section and write it back
to the storage. Per the logic of U-Boot, this means after a reset, the
software will recognize the stored environment settings as "damaged" and turn
to use the default one, which is defined in "default_environment"

With this command, platform bring up owner can maintain a "ready-to-use"
environment settings in software which others can use very conviniently.
U-boot users can also use it to do a environment restore if they want.

-----------------------------------
Usage Example:
> destroyenv

invalidate the CRC
write invalidate enviroment data to storage
Erasing SPI flash...Erasing SPI NOR flash 0xc0000 [0x2000 bytes]
..SUCCESS

Writing to SPI flash...Writing SPI NOR flash
0xc0000 [0x2000 bytes] <- ram 0x276009b8
SUCCESS

done
>
-----------------------------------

Signed-off-by: Eric Sun <jian.sun@freescale.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index cf718e7..c1980da 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -5,7 +5,7 @@
  * (C) Copyright 2001 Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  * Andreas Heppel <aheppel@sysgo.de>
  *
- * Copyright (C) 2010-2011 Freescale Semiconductor, Inc.
+ * Copyright (C) 2010-2012 Freescale Semiconductor, Inc.
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -427,6 +427,16 @@ int do_setenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 	return _do_setenv (flag, argc, argv);
 }
 
+#if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
+int do_destroyenv(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	printf("invalidate the CRC\n");
+	env_crc_destroy();
+	printf("write invalidate enviroment data to storage\n");
+	return saveenv() ? 1 : 0;
+}
+#endif
+
 /************************************************************************
  * Prompt for environment variable
  */
@@ -616,6 +626,15 @@ U_BOOT_CMD(
 	"    - delete environment variable 'name'"
 );
 
+#if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
+U_BOOT_CMD(
+	destroyenv, CONFIG_SYS_MAXARGS, 0,	do_destroyenv,
+	"destroy enviroment variables stored in medium",
+	"\n    - destroy all environment variables in medium"
+	"\n      after reset the default settings will be used"
+);
+#endif
+
 #if defined(CONFIG_CMD_ASKENV)
 
 U_BOOT_CMD(