fw_env: add NAND support

Add support for environment in NAND with automatic NOR / NAND recognition,
including unaligned environment, bad-block skipping, redundant environment
copy.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>

3 files changed, 611 insertions, 264 deletions

diff --git a/tools/env/README b/tools/env/README
index f8a644e..91e679a 100644
--- a/tools/env/README
+++ b/tools/env/README
@@ -22,9 +22,11 @@ following lines are relevant:
 #define DEVICE1_OFFSET    0x0000
 #define ENV1_SIZE         0x4000
 #define DEVICE1_ESIZE     0x4000
+#define DEVICE1_ENVSECTORS     2
 #define DEVICE2_OFFSET    0x0000
 #define ENV2_SIZE         0x4000
 #define DEVICE2_ESIZE     0x4000
+#define DEVICE2_ENVSECTORS     2
 
 Current configuration matches the environment layout of the TRAB
 board.
@@ -46,3 +48,7 @@ then 1 sector.
 
 DEVICEx_ESIZE defines the size of the first sector in the flash
 partition where the environment resides.
+
+DEVICEx_ENVSECTORS defines the number of sectors that may be used for
+this environment instance. On NAND this is used to limit the range
+within which bad blocks are skipped, on NOR it is not used.
diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index e4fc02d..b6036c8 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -2,6 +2,9 @@
  * (C) Copyright 2000-2008
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  *
+ * (C) Copyright 2008
+ * Guennadi Liakhovetski, DENX Software Engineering, lg@denx.de.
+ *
  * See file CREDITS for list of people who contributed to this
  * project.
  *
@@ -45,36 +48,75 @@
 #define	CMD_GETENV	"fw_printenv"
 #define	CMD_SETENV	"fw_setenv"
 
-typedef struct envdev_s {
+#define min(x, y) ({				\
+	typeof(x) _min1 = (x);			\
+	typeof(y) _min2 = (y);			\
+	(void) (&_min1 == &_min2);		\
+	_min1 < _min2 ? _min1 : _min2; })
+
+struct envdev_s {
 	char devname[16];		/* Device name */
 	ulong devoff;			/* Device offset */
 	ulong env_size;			/* environment size */
 	ulong erase_size;		/* device erase size */
-} envdev_t;
+	ulong env_sectors;		/* number of environment sectors */
+	uint8_t mtd_type;		/* type of the MTD device */
+};
 
-static envdev_t envdevices[2];
-static int curdev;
+static struct envdev_s envdevices[2] =
+{
+	{
+		.mtd_type = MTD_ABSENT,
+	}, {
+		.mtd_type = MTD_ABSENT,
+	},
+};
+static int dev_current;
 
 #define DEVNAME(i)    envdevices[(i)].devname
 #define DEVOFFSET(i)  envdevices[(i)].devoff
 #define ENVSIZE(i)    envdevices[(i)].env_size
 #define DEVESIZE(i)   envdevices[(i)].erase_size
+#define ENVSECTORS(i) envdevices[(i)].env_sectors
+#define DEVTYPE(i)    envdevices[(i)].mtd_type
 
-#define CFG_ENV_SIZE ENVSIZE(curdev)
+#define CFG_ENV_SIZE ENVSIZE(dev_current)
 
 #define ENV_SIZE      getenvsize()
 
-typedef struct environment_s {
-	ulong crc;			/* CRC32 over data bytes    */
-	unsigned char flags;		/* active or obsolete */
-	char *data;
-} env_t;
+struct env_image_single {
+	uint32_t	crc;	/* CRC32 over data bytes    */
+	char		data[];
+};
 
-static env_t environment;
+struct env_image_redundant {
+	uint32_t	crc;	/* CRC32 over data bytes    */
+	unsigned char	flags;	/* active or obsolete */
+	char		data[];
+};
+
+enum flag_scheme {
+	FLAG_NONE,
+	FLAG_BOOLEAN,
+	FLAG_INCREMENTAL,
+};
+
+struct environment {
+	void			*image;
+	uint32_t		*crc;
+	unsigned char		*flags;
+	char			*data;
+	enum flag_scheme	flag_scheme;
+};
+
+static struct environment environment = {
+	.flag_scheme = FLAG_NONE,
+};
 
 static int HaveRedundEnv = 0;
 
 static unsigned char active_flag = 1;
+/* obsolete_flag must be 0 to efficiently set it on NOR flash without erasing */
 static unsigned char obsolete_flag = 0;
 
 
@@ -157,7 +199,7 @@ static char default_environment[] = {
 #ifdef  CONFIG_EXTRA_ENV_SETTINGS
 	CONFIG_EXTRA_ENV_SETTINGS
 #endif
-	"\0"			/* Termimate env_t data with 2 NULs */
+	"\0"		/* Termimate struct environment data with 2 NULs */
 };
 
 static int flash_io (int mode);
@@ -186,7 +228,7 @@ char *fw_getenv (char *name)
 	char *env, *nxt;
 
 	if (env_init ())
-		return (NULL);
+		return NULL;
 
 	for (env = environment.data; *env; env = nxt + 1) {
 		char *val;
@@ -195,15 +237,15 @@ char *fw_getenv (char *name)
 			if (nxt >= &environment.data[ENV_SIZE]) {
 				fprintf (stderr, "## Error: "
 					"environment not terminated\n");
-				return (NULL);
+				return NULL;
 			}
 		}
 		val = envmatch (name, env);
 		if (!val)
 			continue;
-		return (val);
+		return val;
 	}
-	return (NULL);
+	return NULL;
 }
 
 /*
@@ -217,7 +259,7 @@ int fw_printenv (int argc, char *argv[])
 	int rc = 0;
 
 	if (env_init ())
-		return (-1);
+		return -1;
 
 	if (argc == 1) {		/* Print all env variables  */
 		for (env = environment.data; *env; env = nxt + 1) {
@@ -225,13 +267,13 @@ int fw_printenv (int argc, char *argv[])
 				if (nxt >= &environment.data[ENV_SIZE]) {
 					fprintf (stderr, "## Error: "
 						"environment not terminated\n");
-					return (-1);
+					return -1;
 				}
 			}
 
 			printf ("%s\n", env);
 		}
-		return (0);
+		return 0;
 	}
 
 	if (strcmp (argv[1], "-n") == 0) {
@@ -241,7 +283,7 @@ int fw_printenv (int argc, char *argv[])
 		if (argc != 2) {
 			fprintf (stderr, "## Error: "
 				"`-n' option requires exactly one argument\n");
-			return (-1);
+			return -1;
 		}
 	} else {
 		n_flag = 0;
@@ -257,7 +299,7 @@ int fw_printenv (int argc, char *argv[])
 				if (nxt >= &environment.data[ENV_SIZE]) {
 					fprintf (stderr, "## Error: "
 						"environment not terminated\n");
-					return (-1);
+					return -1;
 				}
 			}
 			val = envmatch (name, env);
@@ -276,11 +318,11 @@ int fw_printenv (int argc, char *argv[])
 		}
 	}
 
-	return (rc);
+	return rc;
 }
 
 /*
- * Deletes or sets environment variables. Returns errno style error codes:
+ * Deletes or sets environment variables. Returns -1 and sets errno error codes:
  * 0	  - OK
  * EINVAL - need at least 1 argument
  * EROFS  - certain variables ("ethaddr", "serial#") cannot be
@@ -295,11 +337,12 @@ int fw_setenv (int argc, char *argv[])
 	char *name;
 
 	if (argc < 2) {
-		return (EINVAL);
+		errno = EINVAL;
+		return -1;
 	}
 
 	if (env_init ())
-		return (errno);
+		return -1;
 
 	name = argv[1];
 
@@ -311,7 +354,8 @@ int fw_setenv (int argc, char *argv[])
 			if (nxt >= &environment.data[ENV_SIZE]) {
 				fprintf (stderr, "## Error: "
 					"environment not terminated\n");
-				return (EINVAL);
+				errno = EINVAL;
+				return -1;
 			}
 		}
 		if ((oldval = envmatch (name, env)) != NULL)
@@ -328,7 +372,8 @@ int fw_setenv (int argc, char *argv[])
 		if ((strcmp (name, "ethaddr") == 0) ||
 			(strcmp (name, "serial#") == 0)) {
 			fprintf (stderr, "Can't overwrite \"%s\"\n", name);
-			return (EROFS);
+			errno = EROFS;
+			return -1;
 		}
 
 		if (*++nxt == '\0') {
@@ -367,7 +412,7 @@ int fw_setenv (int argc, char *argv[])
 		fprintf (stderr,
 			"Error: environment overflow, \"%s\" deleted\n",
 			name);
-		return (-1);
+		return -1;
 	}
 	while ((*env = *name++) != '\0')
 		env++;
@@ -383,195 +428,430 @@ int fw_setenv (int argc, char *argv[])
 
   WRITE_FLASH:
 
-	/* Update CRC */
-	environment.crc = crc32 (0, (uint8_t*) environment.data, ENV_SIZE);
+	/*
+	 * Update CRC
+	 */
+	*environment.crc = crc32 (0, (uint8_t *) environment.data, ENV_SIZE);
 
 	/* write environment back to flash */
 	if (flash_io (O_RDWR)) {
 		fprintf (stderr, "Error: can't write fw_env to flash\n");
-		return (-1);
+		return -1;
 	}
 
-	return (0);
+	return 0;
 }
 
-static int flash_io (int mode)
+/*
+ * Test for bad block on NAND, just returns 0 on NOR, on NAND:
+ * 0	- block is good
+ * > 0	- block is bad
+ * < 0	- failed to test
+ */
+static int flash_bad_block (int fd, uint8_t mtd_type, loff_t *blockstart)
 {
-	int fd, fdr, rc, otherdev, len, resid;
-	struct erase_info_user erase;
-	char *data = NULL;
+	if (mtd_type == MTD_NANDFLASH) {
+		int badblock = ioctl (fd, MEMGETBADBLOCK, blockstart);
 
-	if ((fd = open (DEVNAME (curdev), mode)) < 0) {
-		fprintf (stderr,
-			"Can't open %s: %s\n",
-			DEVNAME (curdev), strerror (errno));
-		return (-1);
+		if (badblock < 0) {
+			perror ("Cannot read bad block mark");
+			return badblock;
+		}
+
+		if (badblock) {
+#ifdef DEBUG
+			fprintf (stderr, "Bad block at 0x%llx, "
+				 "skipping\n", *blockstart);
+#endif
+			return badblock;
+		}
 	}
 
-	len = sizeof (environment.crc);
-	if (HaveRedundEnv) {
-		len += sizeof (environment.flags);
+	return 0;
+}
+
+/*
+ * Read data from flash at an offset into a provided buffer. On NAND it skips
+ * bad blocks but makes sure it stays within ENVSECTORS (dev) starting from
+ * the DEVOFFSET (dev) block. On NOR the loop is only run once.
+ */
+static int flash_read_buf (int dev, int fd, void *buf, size_t count,
+			   off_t offset, uint8_t mtd_type)
+{
+	size_t blocklen;	/* erase / write length - one block on NAND,
+				   0 on NOR */
+	size_t processed = 0;	/* progress counter */
+	size_t readlen = count;	/* current read length */
+	off_t top_of_range;	/* end of the last block we may use */
+	off_t block_seek;	/* offset inside the current block to the start
+				   of the data */
+	loff_t blockstart;	/* running start of the current block -
+				   MEMGETBADBLOCK needs 64 bits */
+	int rc;
+
+	/*
+	 * Start of the first block to be read, relies on the fact, that
+	 * erase sector size is always a power of 2
+	 */
+	blockstart = offset & ~(DEVESIZE (dev) - 1);
+
+	/* Offset inside a block */
+	block_seek = offset - blockstart;
+
+	if (mtd_type == MTD_NANDFLASH) {
+		/*
+		 * NAND: calculate which blocks we are reading. We have
+		 * to read one block at a time to skip bad blocks.
+		 */
+		blocklen = DEVESIZE (dev);
+
+		/*
+		 * To calculate the top of the range, we have to use the
+		 * global DEVOFFSET (dev), which can be different from offset
+		 */
+		top_of_range = (DEVOFFSET (dev) & ~(blocklen - 1)) +
+			ENVSECTORS (dev) * blocklen;
+
+		/* Limit to one block for the first read */
+		if (readlen > blocklen - block_seek)
+			readlen = blocklen - block_seek;
+	} else {
+		blocklen = 0;
+		top_of_range = offset + count;
 	}
 
-	if (mode == O_RDWR) {
-		if (HaveRedundEnv) {
-			/* switch to next partition for writing */
-			otherdev = !curdev;
-			if ((fdr = open (DEVNAME (otherdev), mode)) < 0) {
-				fprintf (stderr,
-					"Can't open %s: %s\n",
-					DEVNAME (otherdev),
-					strerror (errno));
-				return (-1);
-			}
-		} else {
-			otherdev = curdev;
-			fdr = fd;
-		}
-		printf ("Unlocking flash...\n");
-		erase.length = DEVESIZE (otherdev);
-		erase.start = DEVOFFSET (otherdev);
-		ioctl (fdr, MEMUNLOCK, &erase);
+	/* This only runs once on NOR flash */
+	while (processed < count) {
+		rc = flash_bad_block (fd, mtd_type, &blockstart);
+		if (rc < 0)		/* block test failed */
+			return -1;
 
-		if (HaveRedundEnv) {
-			erase.length = DEVESIZE (curdev);
-			erase.start = DEVOFFSET (curdev);
-			ioctl (fd, MEMUNLOCK, &erase);
-			environment.flags = active_flag;
+		if (blockstart + block_seek + readlen > top_of_range) {
+			/* End of range is reached */
+			fprintf (stderr,
+				 "Too few good blocks within range\n");
+			return -1;
 		}
 
-		printf ("Done\n");
-		resid = DEVESIZE (otherdev) - CFG_ENV_SIZE;
-		if (resid) {
-			if ((data = malloc (resid)) == NULL) {
-				fprintf (stderr,
-					"Cannot malloc %d bytes: %s\n",
-					resid,
-					strerror (errno));
-				return (-1);
-			}
-			if (lseek (fdr, DEVOFFSET (otherdev) + CFG_ENV_SIZE, SEEK_SET)
-				== -1) {
-				fprintf (stderr, "seek error on %s: %s\n",
-					DEVNAME (otherdev),
-					strerror (errno));
-				return (-1);
-			}
-			if ((rc = read (fdr, data, resid)) != resid) {
-				fprintf (stderr,
-					"read error on %s: %s\n",
-					DEVNAME (otherdev),
-					strerror (errno));
-				return (-1);
-			}
+		if (rc) {		/* block is bad */
+			blockstart += blocklen;
+			continue;
 		}
 
-		printf ("Erasing old environment...\n");
+		/*
+		 * If a block is bad, we retry in the next block at the same
+		 * offset - see common/env_nand.c::writeenv()
+		 */
+		lseek (fd, blockstart + block_seek, SEEK_SET);
 
-		erase.length = DEVESIZE (otherdev);
-		erase.start = DEVOFFSET (otherdev);
-		if (ioctl (fdr, MEMERASE, &erase) != 0) {
-			fprintf (stderr, "MTD erase error on %s: %s\n",
-				DEVNAME (otherdev),
-				strerror (errno));
-			return (-1);
+		rc = read (fd, buf + processed, readlen);
+		if (rc != readlen) {
+			fprintf (stderr, "Read error on %s: %s\n",
+				 DEVNAME (dev), strerror (errno));
+			return -1;
 		}
+#ifdef DEBUG
+		fprintf (stderr, "Read 0x%x bytes at 0x%llx\n",
+			 rc, blockstart + block_seek);
+#endif
+		processed += readlen;
+		readlen = min (blocklen, count - processed);
+		block_seek = 0;
+		blockstart += blocklen;
+	}
+
+	return processed;
+}
+
+/*
+ * Write count bytes at offset, but stay within ENVSETCORS (dev) sectors of
+ * DEVOFFSET (dev). Similar to the read case above, on NOR we erase and write
+ * the whole data at once.
+ */
+static int flash_write_buf (int dev, int fd, void *buf, size_t count,
+			    off_t offset, uint8_t mtd_type)
+{
+	void *data;
+	struct erase_info_user erase;
+	size_t blocklen;	/* length of NAND block / NOR erase sector */
+	size_t erase_len;	/* whole area that can be erased - may include
+				   bad blocks */
+	size_t erasesize;	/* erase / write length - one block on NAND,
+				   whole area on NOR */
+	size_t processed = 0;	/* progress counter */
+	size_t write_total;	/* total size to actually write - excludinig
+				   bad blocks */
+	off_t erase_offset;	/* offset to the first erase block (aligned)
+				   below offset */
+	off_t block_seek;	/* offset inside the erase block to the start
+				   of the data */
+	off_t top_of_range;	/* end of the last block we may use */
+	loff_t blockstart;	/* running start of the current block -
+				   MEMGETBADBLOCK needs 64 bits */
+	int rc;
+
+	blocklen = DEVESIZE (dev);
+
+	/* Erase sector size is always a power of 2 */
+	top_of_range = (DEVOFFSET (dev) & ~(blocklen - 1)) +
+		ENVSECTORS (dev) * blocklen;
 
-		printf ("Done\n");
+	erase_offset = offset & ~(blocklen - 1);
 
-		printf ("Writing environment to %s...\n", DEVNAME (otherdev));
-		if (lseek (fdr, DEVOFFSET (otherdev), SEEK_SET) == -1) {
+	/* Maximum area we may use */
+	erase_len = top_of_range - erase_offset;
+
+	blockstart = erase_offset;
+	/* Offset inside a block */
+	block_seek = offset - erase_offset;
+
+	/*
+	 * Data size we actually have to write: from the start of the block
+	 * to the start of the data, then count bytes of data, and to the
+	 * end of the block
+	 */
+	write_total = (block_seek + count + blocklen - 1) & ~(blocklen - 1);
+
+	/*
+	 * Support data anywhere within erase sectors: read out the complete
+	 * area to be erased, replace the environment image, write the whole
+	 * block back again.
+	 */
+	if (write_total > count) {
+		data = malloc (erase_len);
+		if (!data) {
 			fprintf (stderr,
-				"seek error on %s: %s\n",
-				DEVNAME (otherdev), strerror (errno));
-			return (-1);
+				 "Cannot malloc %u bytes: %s\n",
+				 erase_len, strerror (errno));
+			return -1;
 		}
-		if (write (fdr, &environment, len) != len) {
-			fprintf (stderr,
-				"CRC write error on %s: %s\n",
-				DEVNAME (otherdev), strerror (errno));
-			return (-1);
+
+		rc = flash_read_buf (dev, fd, data, write_total, erase_offset,
+				     mtd_type);
+		if (write_total != rc)
+			return -1;
+
+		/* Overwrite the old environment */
+		memcpy (data + block_seek, buf, count);
+	} else {
+		/*
+		 * We get here, iff offset is block-aligned and count is a
+		 * multiple of blocklen - see write_total calculation above
+		 */
+		data = buf;
+	}
+
+	if (mtd_type == MTD_NANDFLASH) {
+		/*
+		 * NAND: calculate which blocks we are writing. We have
+		 * to write one block at a time to skip bad blocks.
+		 */
+		erasesize = blocklen;
+	} else {
+		erasesize = erase_len;
+	}
+
+	erase.length = erasesize;
+
+	/* This only runs once on NOR flash */
+	while (processed < write_total) {
+		rc = flash_bad_block (fd, mtd_type, &blockstart);
+		if (rc < 0)		/* block test failed */
+			return rc;
+
+		if (blockstart + erasesize > top_of_range) {
+			fprintf (stderr, "End of range reached, aborting\n");
+			return -1;
 		}
-		if (write (fdr, environment.data, ENV_SIZE) != ENV_SIZE) {
+
+		if (rc) {		/* block is bad */
+			blockstart += blocklen;
+			continue;
+		}
+
+		erase.start = blockstart;
+		ioctl (fd, MEMUNLOCK, &erase);
+
+		if (ioctl (fd, MEMERASE, &erase) != 0) {
+			fprintf (stderr, "MTD erase error on %s: %s\n",
+				 DEVNAME (dev),
+				 strerror (errno));
+			return -1;
+		}
+
+		if (lseek (fd, blockstart, SEEK_SET) == -1) {
 			fprintf (stderr,
-				"Write error on %s: %s\n",
-				DEVNAME (otherdev), strerror (errno));
-			return (-1);
+				 "Seek error on %s: %s\n",
+				 DEVNAME (dev), strerror (errno));
+			return -1;
 		}
-		if (resid) {
-			if (write (fdr, data, resid) != resid) {
-				fprintf (stderr,
-					"write error on %s: %s\n",
-					DEVNAME (curdev), strerror (errno));
-				return (-1);
-			}
-			free (data);
+
+#ifdef DEBUG
+		printf ("Write 0x%x bytes at 0x%llx\n", erasesize, blockstart);
+#endif
+		if (write (fd, data + processed, erasesize) != erasesize) {
+			fprintf (stderr, "Write error on %s: %s\n",
+				 DEVNAME (dev), strerror (errno));
+			return -1;
 		}
+
+		ioctl (fd, MEMLOCK, &erase);
+
+		processed  += blocklen;
+		block_seek = 0;
+		blockstart += blocklen;
+	}
+
+	if (write_total > count)
+		free (data);
+
+	return processed;
+}
+
+/*
+ * Set obsolete flag at offset - NOR flash only
+ */
+static int flash_flag_obsolete (int dev, int fd, off_t offset)
+{
+	int rc;
+
+	/* This relies on the fact, that obsolete_flag == 0 */
+	rc = lseek (fd, offset, SEEK_SET);
+	if (rc < 0) {
+		fprintf (stderr, "Cannot seek to set the flag on %s \n",
+			 DEVNAME (dev));
+		return rc;
+	}
+	rc = write (fd, &obsolete_flag, sizeof (obsolete_flag));
+	if (rc < 0)
+		perror ("Could not set obsolete flag");
+
+	return rc;
+}
+
+static int flash_write (int fd_current, int fd_target, int dev_target)
+{
+	int rc;
+
+	switch (environment.flag_scheme) {
+	case FLAG_NONE:
+		break;
+	case FLAG_INCREMENTAL:
+		(*environment.flags)++;
+		break;
+	case FLAG_BOOLEAN:
+		*environment.flags = active_flag;
+		break;
+	default:
+		fprintf (stderr, "Unimplemented flash scheme %u \n",
+			 environment.flag_scheme);
+		return -1;
+	}
+
+#ifdef DEBUG
+	printf ("Writing new environment at 0x%lx on %s\n",
+		DEVOFFSET (dev_target), DEVNAME (dev_target));
+#endif
+	rc = flash_write_buf (dev_target, fd_target, environment.image,
+			      CFG_ENV_SIZE, DEVOFFSET (dev_target),
+			      DEVTYPE(dev_target));
+	if (rc < 0)
+		return rc;
+
+	if (environment.flag_scheme == FLAG_BOOLEAN) {
+		/* Have to set obsolete flag */
+		off_t offset = DEVOFFSET (dev_current) +
+			offsetof (struct env_image_redundant, flags);
+#ifdef DEBUG
+		printf ("Setting obsolete flag in environment at 0x%lx on %s\n",
+			DEVOFFSET (dev_current), DEVNAME (dev_current));
+#endif
+		flash_flag_obsolete (dev_current, fd_current, offset);
+	}
+
+	return 0;
+}
+
+static int flash_read (int fd)
+{
+	struct mtd_info_user mtdinfo;
+	int rc;
+
+	rc = ioctl (fd, MEMGETINFO, &mtdinfo);
+	if (rc < 0) {
+		perror ("Cannot get MTD information");
+		return -1;
+	}
+
+	if (mtdinfo.type != MTD_NORFLASH && mtdinfo.type != MTD_NANDFLASH) {
+		fprintf (stderr, "Unsupported flash type %u\n", mtdinfo.type);
+		return -1;
+	}
+
+	DEVTYPE(dev_current) = mtdinfo.type;
+
+	rc = flash_read_buf (dev_current, fd, environment.image, CFG_ENV_SIZE,
+			     DEVOFFSET (dev_current), mtdinfo.type);
+
+	return (rc != CFG_ENV_SIZE) ? -1 : 0;
+}
+
+static int flash_io (int mode)
+{
+	int fd_current, fd_target, rc, dev_target;
+
+	/* dev_current: fd_current, erase_current */
+	fd_current = open (DEVNAME (dev_current), mode);
+	if (fd_current < 0) {
+		fprintf (stderr,
+			 "Can't open %s: %s\n",
+			 DEVNAME (dev_current), strerror (errno));
+		return -1;
+	}
+
+	if (mode == O_RDWR) {
 		if (HaveRedundEnv) {
-			/* change flag on current active env partition */
-			if (lseek (fd, DEVOFFSET (curdev) + sizeof (ulong), SEEK_SET)
-				== -1) {
-				fprintf (stderr, "seek error on %s: %s\n",
-					DEVNAME (curdev), strerror (errno));
-				return (-1);
-			}
-			if (write (fd, &obsolete_flag, sizeof (obsolete_flag)) !=
-				sizeof (obsolete_flag)) {
+			/* switch to next partition for writing */
+			dev_target = !dev_current;
+			/* dev_target: fd_target, erase_target */
+			fd_target = open (DEVNAME (dev_target), mode);
+			if (fd_target < 0) {
 				fprintf (stderr,
-					"Write error on %s: %s\n",
-					DEVNAME (curdev), strerror (errno));
-				return (-1);
+					 "Can't open %s: %s\n",
+					 DEVNAME (dev_target),
+					 strerror (errno));
+				rc = -1;
+				goto exit;
 			}
+		} else {
+			dev_target = dev_current;
+			fd_target = fd_current;
 		}
-		printf ("Done\n");
-		printf ("Locking ...\n");
-		erase.length = DEVESIZE (otherdev);
-		erase.start = DEVOFFSET (otherdev);
-		ioctl (fdr, MEMLOCK, &erase);
+
+		rc = flash_write (fd_current, fd_target, dev_target);
+
 		if (HaveRedundEnv) {
-			erase.length = DEVESIZE (curdev);
-			erase.start = DEVOFFSET (curdev);
-			ioctl (fd, MEMLOCK, &erase);
-			if (close (fdr)) {
+			if (close (fd_target)) {
 				fprintf (stderr,
 					"I/O error on %s: %s\n",
-					DEVNAME (otherdev),
+					DEVNAME (dev_target),
 					strerror (errno));
-				return (-1);
+				rc = -1;
 			}
 		}
-		printf ("Done\n");
 	} else {
-
-		if (lseek (fd, DEVOFFSET (curdev), SEEK_SET) == -1) {
-			fprintf (stderr,
-				"seek error on %s: %s\n",
-				DEVNAME (curdev), strerror (errno));
-			return (-1);
-		}
-		if (read (fd, &environment, len) != len) {
-			fprintf (stderr,
-				"CRC read error on %s: %s\n",
-				DEVNAME (curdev), strerror (errno));
-			return (-1);
-		}
-		if ((rc = read (fd, environment.data, ENV_SIZE)) != ENV_SIZE) {
-			fprintf (stderr,
-				"Read error on %s: %s\n",
-				DEVNAME (curdev), strerror (errno));
-			return (-1);
-		}
+		rc = flash_read (fd_current);
 	}
 
-	if (close (fd)) {
+exit:
+	if (close (fd_current)) {
 		fprintf (stderr,
-			"I/O error on %s: %s\n",
-			DEVNAME (curdev), strerror (errno));
-		return (-1);
+			 "I/O error on %s: %s\n",
+			 DEVNAME (dev_current), strerror (errno));
+		return -1;
 	}
 
-	/* everything ok */
-	return (0);
+	return rc;
 }
 
 /*
@@ -585,10 +865,10 @@ static char *envmatch (char * s1, char * s2)
 
 	while (*s1 == *s2++)
 		if (*s1++ == '=')
-			return (s2);
+			return s2;
 	if (*s1 == '\0' && *(s2 - 1) == '=')
-		return (s2);
-	return (NULL);
+		return s2;
+	return NULL;
 }
 
 /*
@@ -596,108 +876,156 @@ static char *envmatch (char * s1, char * s2)
  */
 static int env_init (void)
 {
+	int crc0, crc0_ok;
+	char flag0;
+	void *addr0;
+
 	int crc1, crc1_ok;
-	char *addr1;
+	char flag1;
+	void *addr1;
 
-	int crc2, crc2_ok;
-	char flag1, flag2, *addr2;
+	struct env_image_single *single;
+	struct env_image_redundant *redundant;
 
 	if (parse_config ())		/* should fill envdevices */
-		return 1;
+		return -1;
 
-	if ((addr1 = calloc (1, ENV_SIZE)) == NULL) {
+	addr0 = calloc (1, CFG_ENV_SIZE);
+	if (addr0 == NULL) {
 		fprintf (stderr,
 			"Not enough memory for environment (%ld bytes)\n",
-			ENV_SIZE);
-		return (errno);
+			CFG_ENV_SIZE);
+		return -1;
 	}
 
 	/* read environment from FLASH to local buffer */
-	environment.data = addr1;
-	curdev = 0;
-	if (flash_io (O_RDONLY)) {
-		return (errno);
+	environment.image = addr0;
+
+	if (HaveRedundEnv) {
+		redundant = addr0;
+		environment.crc		= &redundant->crc;
+		environment.flags	= &redundant->flags;
+		environment.data	= redundant->data;
+	} else {
+		single = addr0;
+		environment.crc		= &single->crc;
+		environment.flags	= NULL;
+		environment.data	= single->data;
 	}
 
-	crc1_ok = ((crc1 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE))
-			   == environment.crc);
+	dev_current = 0;
+	if (flash_io (O_RDONLY))
+		return -1;
+
+	crc0 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE);
+	crc0_ok = (crc0 == *environment.crc);
 	if (!HaveRedundEnv) {
-		if (!crc1_ok) {
+		if (!crc0_ok) {
 			fprintf (stderr,
 				"Warning: Bad CRC, using default environment\n");
 			memcpy(environment.data, default_environment, sizeof default_environment);
 		}
 	} else {
-		flag1 = environment.flags;
+		flag0 = *environment.flags;
 
-		curdev = 1;
-		if ((addr2 = calloc (1, ENV_SIZE)) == NULL) {
+		dev_current = 1;
+		addr1 = calloc (1, CFG_ENV_SIZE);
+		if (addr1 == NULL) {
 			fprintf (stderr,
 				"Not enough memory for environment (%ld bytes)\n",
-				ENV_SIZE);
-			return (errno);
+				CFG_ENV_SIZE);
+			return -1;
 		}
-		environment.data = addr2;
+		redundant = addr1;
 
-		if (flash_io (O_RDONLY)) {
-			return (errno);
+		/*
+		 * have to set environment.image for flash_read(), careful -
+		 * other pointers in environment still point inside addr0
+		 */
+		environment.image = addr1;
+		if (flash_io (O_RDONLY))
+			return -1;
+
+		/* Check flag scheme compatibility */
+		if (DEVTYPE(dev_current) == MTD_NORFLASH &&
+		    DEVTYPE(!dev_current) == MTD_NORFLASH) {
+			environment.flag_scheme = FLAG_BOOLEAN;
+		} else if (DEVTYPE(dev_current) == MTD_NANDFLASH &&
+			   DEVTYPE(!dev_current) == MTD_NANDFLASH) {
+			environment.flag_scheme = FLAG_INCREMENTAL;
+		} else {
+			fprintf (stderr, "Incompatible flash types!\n");
+			return -1;
 		}
 
-		crc2_ok = ((crc2 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE))
-				   == environment.crc);
-		flag2 = environment.flags;
-
-		if (crc1_ok && !crc2_ok) {
-			environment.data = addr1;
-			environment.flags = flag1;
-			environment.crc = crc1;
-			curdev = 0;
-			free (addr2);
-		} else if (!crc1_ok && crc2_ok) {
-			environment.data = addr2;
-			environment.flags = flag2;
-			environment.crc = crc2;
-			curdev = 1;
-			free (addr1);
-		} else if (!crc1_ok && !crc2_ok) {
+		crc1 = crc32 (0, (uint8_t *) redundant->data, ENV_SIZE);
+		crc1_ok = (crc1 == redundant->crc);
+		flag1 = redundant->flags;
+
+		if (crc0_ok && !crc1_ok) {
+			dev_current = 0;
+		} else if (!crc0_ok && crc1_ok) {
+			dev_current = 1;
+		} else if (!crc0_ok && !crc1_ok) {
 			fprintf (stderr,
 				"Warning: Bad CRC, using default environment\n");
-			memcpy(environment.data, default_environment, sizeof default_environment);
-			curdev = 0;
-			free (addr1);
-		} else if (flag1 == active_flag && flag2 == obsolete_flag) {
-			environment.data = addr1;
-			environment.flags = flag1;
-			environment.crc = crc1;
-			curdev = 0;
-			free (addr2);
-		} else if (flag1 == obsolete_flag && flag2 == active_flag) {
-			environment.data = addr2;
-			environment.flags = flag2;
-			environment.crc = crc2;
-			curdev = 1;
-			free (addr1);
-		} else if (flag1 == flag2) {
-			environment.data = addr1;
-			environment.flags = flag1;
-			environment.crc = crc1;
-			curdev = 0;
-			free (addr2);
-		} else if (flag1 == 0xFF) {
-			environment.data = addr1;
-			environment.flags = flag1;
-			environment.crc = crc1;
-			curdev = 0;
-			free (addr2);
-		} else if (flag2 == 0xFF) {
-			environment.data = addr2;
-			environment.flags = flag2;
-			environment.crc = crc2;
-			curdev = 1;
+			memcpy (environment.data, default_environment,
+				sizeof default_environment);
+			dev_current = 0;
+		} else {
+			switch (environment.flag_scheme) {
+			case FLAG_BOOLEAN:
+				if (flag0 == active_flag &&
+				    flag1 == obsolete_flag) {
+					dev_current = 0;
+				} else if (flag0 == obsolete_flag &&
+					   flag1 == active_flag) {
+					dev_current = 1;
+				} else if (flag0 == flag1) {
+					dev_current = 0;
+				} else if (flag0 == 0xFF) {
+					dev_current = 0;
+				} else if (flag1 == 0xFF) {
+					dev_current = 1;
+				} else {
+					dev_current = 0;
+				}
+				break;
+			case FLAG_INCREMENTAL:
+				if ((flag0 == 255 && flag1 == 0) ||
+				    flag1 > flag0)
+					dev_current = 1;
+				else if ((flag1 == 255 && flag0 == 0) ||
+					 flag0 > flag1)
+					dev_current = 0;
+				else /* flags are equal - almost impossible */
+					dev_current = 0;
+				break;
+			default:
+				fprintf (stderr, "Unknown flag scheme %u \n",
+					 environment.flag_scheme);
+				return -1;
+			}
+		}
+
+		/*
+		 * If we are reading, we don't need the flag and the CRC any
+		 * more, if we are writing, we will re-calculate CRC and update
+		 * flags before writing out
+		 */
+		if (dev_current) {
+			environment.image	= addr1;
+			environment.crc		= &redundant->crc;
+			environment.flags	= &redundant->flags;
+			environment.data	= redundant->data;
+			free (addr0);
+		} else {
+			environment.image	= addr0;
+			/* Other pointers are already set */
 			free (addr1);
 		}
 	}
-	return (0);
+	return 0;
 }
 
 
@@ -710,18 +1038,20 @@ static int parse_config ()
 	if (get_config (CONFIG_FILE)) {
 		fprintf (stderr,
 			"Cannot parse config file: %s\n", strerror (errno));
-		return 1;
+		return -1;
 	}
 #else
 	strcpy (DEVNAME (0), DEVICE1_NAME);
 	DEVOFFSET (0) = DEVICE1_OFFSET;
 	ENVSIZE (0) = ENV1_SIZE;
 	DEVESIZE (0) = DEVICE1_ESIZE;
+	ENVSECTORS (0) = DEVICE1_ENVSECTORS;
 #ifdef HAVE_REDUND
 	strcpy (DEVNAME (1), DEVICE2_NAME);
 	DEVOFFSET (1) = DEVICE2_OFFSET;
 	ENVSIZE (1) = ENV2_SIZE;
 	DEVESIZE (1) = DEVICE2_ESIZE;
+	ENVSECTORS (1) = DEVICE2_ENVSECTORS;
 	HaveRedundEnv = 1;
 #endif
 #endif
@@ -729,14 +1059,14 @@ static int parse_config ()
 		fprintf (stderr,
 			"Cannot access MTD device %s: %s\n",
 			DEVNAME (0), strerror (errno));
-		return 1;
+		return -1;
 	}
 
 	if (HaveRedundEnv && stat (DEVNAME (1), &st)) {
 		fprintf (stderr,
 			"Cannot access MTD device %s: %s\n",
 			DEVNAME (1), strerror (errno));
-		return 1;
+		return -1;
 	}
 	return 0;
 }
@@ -749,21 +1079,28 @@ static int get_config (char *fname)
 	int rc;
 	char dump[128];
 
-	if ((fp = fopen (fname, "r")) == NULL) {
-		return 1;
-	}
-
-	while ((i < 2) && ((rc = fscanf (fp, "%s %lx %lx %lx",
-				  DEVNAME (i),
-				  &DEVOFFSET (i),
-				  &ENVSIZE (i),
-				  &DEVESIZE (i)  )) != EOF)) {
+	fp = fopen (fname, "r");
+	if (fp == NULL)
+		return -1;
 
+	while (i < 2 && fgets (dump, sizeof (dump), fp)) {
 		/* Skip incomplete conversions and comment strings */
-		if ((rc < 3) || (*DEVNAME (i) == '#')) {
-			fgets (dump, sizeof (dump), fp);	/* Consume till end */
+		if (dump[0] == '#')
 			continue;
-		}
+
+		rc = sscanf (dump, "%s %lx %lx %lx %lx",
+			     DEVNAME (i),
+			     &DEVOFFSET (i),
+			     &ENVSIZE (i),
+			     &DEVESIZE (i),
+			     &ENVSECTORS (i));
+
+		if (rc < 4)
+			continue;
+
+		if (rc < 5)
+			/* Default - 1 sector */
+			ENVSECTORS (i) = 1;
 
 		i++;
 	}
@@ -772,7 +1109,7 @@ static int get_config (char *fname)
 	HaveRedundEnv = i - 1;
 	if (!i) {			/* No valid entries found */
 		errno = EINVAL;
-		return 1;
+		return -1;
 	} else
 		return 0;
 }
diff --git a/tools/env/fw_env.config b/tools/env/fw_env.config
index 2432bd8..0fe37c9 100644
--- a/tools/env/fw_env.config
+++ b/tools/env/fw_env.config
@@ -1,7 +1,11 @@
 # Configuration file for fw_(printenv/saveenv) utility.
 # Up to two entries are valid, in this case the redundand
 # environment sector is assumed present.
+# Notice, that the "Number of sectors" is ignored on NOR.
 
-# MTD device name	Device offset	Env. size	Flash sector size
+# MTD device name	Device offset	Env. size	Flash sector size	Number of sectors
 /dev/mtd1		0x0000		0x4000		0x4000
 /dev/mtd2		0x0000		0x4000		0x4000
+
+# NAND example
+#/dev/mtd0		0x4000		0x4000		0x20000			2