This patch adds support for CFG_ENV_OFFSET_PATCHED and 
CFG_ENV_OFFSET_OOB.

Both try to solve the problem of fixing the environment location in NAND flash
at compile time, which doesn't work well if the NAND flash has a bad block at
exactly that location.

CFG_ENV_OFFSET_PATCHED puts the environment in a global variable.  You can then
use the linker script to put that variable to a fixed location in the u-boot
image.  Then you can use bianry patching during the production flash process.

The idea of CFG_ENV_OFFSET_OOB is to store the environment offset in the NAND
OOB data of block 0.  We can do this in case the vendor makes a guarantee that
block 0 never is a factory-default bad block. 

Signed-off-by: Harald Welte <laforge@openmoko.org>

Index: u-boot/common/env_nand.c
===================================================================
--- u-boot.orig/common/env_nand.c
+++ u-boot/common/env_nand.c
@@ -271,6 +271,33 @@
 	ulong total;
 	int ret;
 
+#if defined(CFG_ENV_OFFSET_OOB)
+	struct mtd_info *mtd = &nand_info[0];
+	struct nand_chip *this = mtd->priv;
+	int buf_len;
+	uint8_t *buf;
+
+	buf_len = (1 << this->bbt_erase_shift);
+	buf_len += (buf_len >> this->page_shift) * mtd->oobsize;
+	buf = malloc(buf_len);
+	if (!buf)
+		return;
+
+	nand_read_raw(mtd, buf, 0, mtd->oobblock, mtd->oobsize);
+	if (buf[mtd->oobblock + 8 + 0] == 'E' &&
+	    buf[mtd->oobblock + 8 + 1] == 'N' &&
+	    buf[mtd->oobblock + 8 + 2] == 'V' &&
+	    buf[mtd->oobblock + 8 + 3] == '0') {
+		CFG_ENV_OFFSET = *((unsigned long *) &buf[mtd->oobblock + 8 + 4]);
+		/* fall through to the normal environment reading code below */
+		free(buf);
+		puts("Found Environment offset in OOB..\n");
+	} else {
+		free(buf);
+		return use_default();
+	}
+#endif
+
 	total = CFG_ENV_SIZE;
 	ret = nand_read(&nand_info[0], CFG_ENV_OFFSET, &total, (u_char*)env_ptr);
   	if (ret || total != CFG_ENV_SIZE)
Index: u-boot/common/environment.c
===================================================================
--- u-boot.orig/common/environment.c
+++ u-boot/common/environment.c
@@ -29,6 +29,12 @@
 #undef	__ASSEMBLY__
 #include <environment.h>
 
+#if defined(CFG_ENV_OFFSET_PATCHED)
+unsigned long env_offset = CFG_ENV_OFFSET_PATCHED;
+#elif defined(CFG_ENV_OFFSET_OOB)
+unsigned long env_offset = CFG_ENV_OFFSET_OOB;
+#endif
+
 /*
  * Handle HOSTS that have prepended
  * crap on symbol names, not TARGETS.
Index: u-boot/include/environment.h
===================================================================
--- u-boot.orig/include/environment.h
+++ u-boot/include/environment.h
@@ -70,6 +70,10 @@
 #endif	/* CFG_ENV_IS_IN_FLASH */
 
 #if defined(CFG_ENV_IS_IN_NAND)
+#if defined(CFG_ENV_OFFSET_PATCHED) || defined(CFG_ENV_OFFSET_OOB)
+extern unsigned long env_offset;
+#define CFG_ENV_OFFSET env_offset
+#else
 # ifndef CFG_ENV_OFFSET
 #  error "Need to define CFG_ENV_OFFSET when using CFG_ENV_IS_IN_NAND"
 # endif
@@ -82,6 +86,7 @@
 # ifdef CFG_ENV_IS_EMBEDDED
 #  define ENV_IS_EMBEDDED	1
 # endif
+#endif /* CFG_ENV_NAND_PATCHED */
 #endif /* CFG_ENV_IS_IN_NAND */
 
 
Index: u-boot/common/Makefile
===================================================================
--- u-boot.orig/common/Makefile
+++ u-boot/common/Makefile
@@ -50,6 +50,7 @@
 COBJS-$(CONFIG_CMD_DISPLAY) += cmd_display.o
 COBJS-$(CONFIG_CMD_DOC) += cmd_doc.o
 COBJS-$(CONFIG_CMD_DTT) += cmd_dtt.o
+COBJS-y += cmd_dynenv.o
 COBJS-y += cmd_eeprom.o
 COBJS-$(CONFIG_CMD_ELF) += cmd_elf.o
 COBJS-$(CONFIG_CMD_EXT2) += cmd_ext2.o
Index: u-boot/common/cmd_dynenv.c
===================================================================
--- /dev/null
+++ u-boot/common/cmd_dynenv.c
@@ -0,0 +1,85 @@
+/*
+ * (C) Copyright 2006-2007 OpenMoko, Inc.
+ * Author: Harald Welte <laforge@openmoko.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <command.h>
+#include <malloc.h>
+#include <environment.h>
+#include <nand.h>
+#include <asm/errno.h>
+
+#if defined(CFG_ENV_OFFSET_OOB)
+
+int do_dynenv(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	struct mtd_info *mtd = &nand_info[0];
+	int ret, size = 8;
+	uint8_t *buf;
+
+	char *cmd = argv[1];
+
+	buf = malloc(mtd->oobsize);
+	if (!buf)
+		return -ENOMEM;
+
+	if (!strcmp(cmd, "get")) {
+		ret = mtd->read_oob(mtd, 8, size, (size_t *) &size, (u_char *) buf);
+
+		if (buf[0] == 'E' && buf[1] == 'N' &&
+		    buf[2] == 'V' && buf[3] == '0')
+			printf("0x%08x\n", *((u_int32_t *) &buf[4]));
+		else
+			printf("No dynamic environment marker in OOB block 0\n");
+
+	} else if (!strcmp(cmd, "set")) {
+		unsigned long addr;
+		if (argc < 3)
+			goto usage;
+
+		buf[0] = 'E';
+		buf[1] = 'N';
+		buf[2] = 'V';
+		buf[3] = '0';
+		addr = simple_strtoul(argv[2], NULL, 16);
+		memcpy(buf+4, &addr, 4);
+
+		printf("%02x %02x %02x %02x - %02x %02x %02x %02x\n",
+			buf[0], buf[1], buf[2], buf[3],
+			buf[4], buf[5], buf[6], buf[7]);
+
+		ret = mtd->write_oob(mtd, 8, size, (size_t *) &size, (u_char *) buf);
+	} else
+		goto usage;
+
+	free(buf);
+	return ret;
+
+usage:
+	free(buf);
+	printf("Usage:\n%s\n", cmdtp->usage);
+	return 1;
+}
+
+U_BOOT_CMD(dynenv, 3, 1, do_dynenv,
+	"dynenv  - dynamically placed (NAND) environment\n",
+	"dynenv set off	- set enviromnent offset\n"
+	"dynenv get	- get environment offset\n");
+
+#endif /* CFG_ENV_OFFSET_OOB */
