fw_env: calculate default number of env sectors

The assumed number of environment sectors (always 1) leads to an
incorrect top_of_range calculation in fw.env.c when a flash device has
an erase block size smaller than the environment data size (number of
environment sectors > 1).

This change updates the default number of environment sectors to at
least cover the size of the environment.

Also corrected a false statement about the number of sectors column in
fw_env.config.

Signed-off-by: Dustin Byford <dustin@cumulusnetworks.com>

tools/env/fw_env.c

@@ -1246,9 +1246,10 @@ static int parse_config ()
 	strcpy (DEVNAME (0), DEVICE1_NAME);
 	DEVOFFSET (0) = DEVICE1_OFFSET;
 	ENVSIZE (0) = ENV1_SIZE;
-	/* Default values are: erase-size=env-size, #sectors=1 */
+	/* Default values are: erase-size=env-size */
 	DEVESIZE (0) = ENVSIZE (0);
-	ENVSECTORS (0) = 1;
+	/* #sectors=env-size/erase-size (rounded up) */
+	ENVSECTORS (0) = (ENVSIZE(0) + DEVESIZE(0) - 1) / DEVESIZE(0);
 #ifdef DEVICE1_ESIZE
 	DEVESIZE (0) = DEVICE1_ESIZE;
 #endif
@@ -1260,9 +1261,10 @@ static int parse_config ()
 	strcpy (DEVNAME (1), DEVICE2_NAME);
 	DEVOFFSET (1) = DEVICE2_OFFSET;
 	ENVSIZE (1) = ENV2_SIZE;
-	/* Default values are: erase-size=env-size, #sectors=1 */
+	/* Default values are: erase-size=env-size */
 	DEVESIZE (1) = ENVSIZE (1);
-	ENVSECTORS (1) = 1;
+	/* #sectors=env-size/erase-size (rounded up) */
+	ENVSECTORS (1) = (ENVSIZE(1) + DEVESIZE(1) - 1) / DEVESIZE(1);
 #ifdef DEVICE2_ESIZE
 	DEVESIZE (1) = DEVICE2_ESIZE;
 #endif
@@ -1320,8 +1322,8 @@ static int get_config (char *fname)
 			DEVESIZE(i) = ENVSIZE(i);
 
 		if (rc < 5)
-			/* Default - 1 sector */
-			ENVSECTORS (i) = 1;
+			/* Assume enough env sectors to cover the environment */
+			ENVSECTORS (i) = (ENVSIZE(i) + DEVESIZE(i) - 1) / DEVESIZE(i);
 
 		i++;
 	}

tools/env/fw_env.config

@@ -1,7 +1,7 @@
 # Configuration file for fw_(printenv/setenv) utility.
 # Up to two entries are valid, in this case the redundant
 # environment sector is assumed present.
-# Notice, that the "Number of sectors" is ignored on NOR and SPI-dataflash.
+# Notice, that the "Number of sectors" is not required on NOR and SPI-dataflash.
 # Futhermore, if the Flash sector size is ommitted, this value is assumed to
 # be the same as the Environment size, which is valid for NOR and SPI-dataflash