From 1567b596d9f4a7ff49ebdca29e15a33777dfd670 Mon Sep 17 00:00:00 2001
From: Heiko Schocher <hs@denx.de>
Date: Thu, 7 Jan 2010 08:55:44 +0100
Subject: [PATCH] env, eeprom: add redundant environment support

Add redundant environment support for environment lying on a EEPROM.

Tested on uppcoming suen3 support

Signed-off-by: Andreas Huber <andreas.huber@keymile.com>
---
 common/env_eeprom.c | 131 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 127 insertions(+), 4 deletions(-)

diff --git a/common/env_eeprom.c b/common/env_eeprom.c
index 30de4e9cac..95a7d0d3bc 100644
--- a/common/env_eeprom.c
+++ b/common/env_eeprom.c
@@ -32,6 +32,11 @@
 #include <i2c.h>
 #endif
 
+#ifdef CONFIG_ENV_OFFSET_REDUND
+#define ACTIVE_FLAG   1
+#define OBSOLETE_FLAG 0
+#endif
+
 DECLARE_GLOBAL_DATA_PTR;
 
 env_t *env_ptr = NULL;
@@ -93,9 +98,15 @@ static int eeprom_bus_write (unsigned dev_addr, unsigned offset, uchar *buffer,
 uchar env_get_char_spec (int index)
 {
 	uchar c;
+	unsigned int off;
+	off = CONFIG_ENV_OFFSET;
+#ifdef CONFIG_ENV_OFFSET_REDUND
+	if (gd->env_valid == 2)
+		off = CONFIG_ENV_OFFSET_REDUND;
+#endif
 
 	eeprom_bus_read (CONFIG_SYS_DEF_EEPROM_ADDR,
-		     CONFIG_ENV_OFFSET+index+offsetof(env_t,data),
+		     off + index + offsetof(env_t,data),
 		     &c, 1);
 
 	return (c);
@@ -103,18 +114,52 @@ uchar env_get_char_spec (int index)
 
 void env_relocate_spec (void)
 {
+	unsigned int off = CONFIG_ENV_OFFSET;
+#ifdef CONFIG_ENV_OFFSET_REDUND
+	if (gd->env_valid == 2)
+		off = CONFIG_ENV_OFFSET_REDUND;
+#endif
 	eeprom_bus_read (CONFIG_SYS_DEF_EEPROM_ADDR,
-		     CONFIG_ENV_OFFSET,
+		     off,
 		     (uchar*)env_ptr,
 		     CONFIG_ENV_SIZE);
 }
 
 int saveenv(void)
 {
-	return eeprom_bus_write (CONFIG_SYS_DEF_EEPROM_ADDR,
-			     CONFIG_ENV_OFFSET,
+	int rc;
+	unsigned int off = CONFIG_ENV_OFFSET;
+#ifdef CONFIG_ENV_OFFSET_REDUND
+	unsigned int off_red = CONFIG_ENV_OFFSET_REDUND;
+	char flag_obsolete = OBSOLETE_FLAG;
+	if (gd->env_valid == 1) {
+		off = CONFIG_ENV_OFFSET_REDUND;
+		off_red = CONFIG_ENV_OFFSET;
+	}
+
+	env_ptr->flags = ACTIVE_FLAG;
+#endif
+
+	rc = eeprom_bus_write (CONFIG_SYS_DEF_EEPROM_ADDR,
+			     off,
 			     (uchar *)env_ptr,
 			     CONFIG_ENV_SIZE);
+
+#ifdef CONFIG_ENV_OFFSET_REDUND
+	if (rc == 0) {
+		eeprom_bus_write (CONFIG_SYS_DEF_EEPROM_ADDR,
+				  off_red + offsetof(env_t,flags),
+				  (uchar *)&flag_obsolete,
+				  1);
+		if (gd->env_valid == 1)
+			gd->env_valid = 2;
+		else
+			gd->env_valid = 1;
+
+	}
+#endif
+
+	return rc;
 }
 
 /************************************************************************
@@ -123,6 +168,82 @@ int saveenv(void)
  * We are still running from ROM, so data use is limited
  * Use a (moderately small) buffer on the stack
  */
+
+#ifdef CONFIG_ENV_OFFSET_REDUND
+int env_init(void)
+{
+	ulong len;
+	ulong crc[2], crc_tmp;
+	unsigned int off, off_env[2];
+	uchar buf[64];
+	int crc_ok[2] = {0,0};
+	unsigned char flags[2];
+	int i;
+
+	eeprom_init ();	/* prepare for EEPROM read/write */
+
+	off_env[0] = CONFIG_ENV_OFFSET;
+	off_env[1] = CONFIG_ENV_OFFSET_REDUND;
+
+	for (i = 0; i < 2; i++) {
+		/* read CRC */
+		eeprom_bus_read (CONFIG_SYS_DEF_EEPROM_ADDR,
+			off_env[i] + offsetof(env_t,crc),
+			(uchar *)&crc[i], sizeof(ulong));
+		/* read FLAGS */
+		eeprom_bus_read (CONFIG_SYS_DEF_EEPROM_ADDR,
+			off_env[i] + offsetof(env_t,flags),
+			(uchar *)&flags[i], sizeof(uchar));
+
+		crc_tmp= 0;
+		len = ENV_SIZE;
+		off = off_env[i] + offsetof(env_t,data);
+		while (len > 0) {
+			int n = (len > sizeof(buf)) ? sizeof(buf) : len;
+
+			eeprom_bus_read (CONFIG_SYS_DEF_EEPROM_ADDR, off,
+				buf, n);
+
+			crc_tmp = crc32 (crc_tmp, buf, n);
+			len -= n;
+			off += n;
+		}
+		if (crc_tmp == crc[i])
+			crc_ok[i] = 1;
+	}
+
+	if (!crc_ok[0] && !crc_ok[1]) {
+		gd->env_addr  = 0;
+		gd->env_valid = 0;
+
+		return 0;
+	} else if (crc_ok[0] && !crc_ok[1]) {
+		gd->env_valid = 1;
+	}
+	else if (!crc_ok[0] && crc_ok[1]) {
+		gd->env_valid = 2;
+	} else {
+		/* both ok - check serial */
+		if (flags[0] == ACTIVE_FLAG && flags[1] == OBSOLETE_FLAG)
+			gd->env_valid = 1;
+		else if (flags[0] == OBSOLETE_FLAG && flags[1] == ACTIVE_FLAG)
+			gd->env_valid = 2;
+		else if (flags[0] == 0xFF && flags[1] == 0)
+			gd->env_valid = 2;
+		else if(flags[1] == 0xFF && flags[0] == 0)
+			gd->env_valid = 1;
+		else /* flags are equal - almost impossible */
+			gd->env_valid = 1;
+	}
+
+	if (gd->env_valid == 2)
+		gd->env_addr = off_env[1] + offsetof(env_t,data);
+	else if (gd->env_valid == 1)
+		gd->env_addr = off_env[0] + offsetof(env_t,data);
+
+	return (0);
+}
+#else
 int env_init(void)
 {
 	ulong crc, len, new;
@@ -159,3 +280,5 @@ int env_init(void)
 
 	return (0);
 }
+#endif
+
-- 
2.25.1