[U-Boot] [PATCH 3/4] mtdparts: add new sub-command "spread"

[Ben Gardiner]

This patch introduces the 'spread' sub-command of the mtdparts command.
This command will modify the existing mtdparts variable by increasing
the size of the partitions such that 1) each partition's net size is at
least as large as the size specified in the mtdparts variable and 2)
each partition starts on a good block.

The new subcommand is implemented by iterating over the mtd device
partitions and collecting a bad blocks count in each -- including any
trailing bad blocks -- and then modifying that partitions's part_info
structure and checking if the modification affects the next partition.

---

This patch is based on the idea of Harald Welte <laforge at gnumonks.org>
and the comments of Wolfgang Denk <wd at denx.de> in the review at
http://article.gmane.org/gmane.comp.boot-loaders.u-boot/43549 .

Signed-off-by: Ben Gardiner <bengardiner at nanometrics.ca>
---
 common/cmd_mtdparts.c |  106 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 105 insertions(+), 1 deletions(-)

diff --git a/common/cmd_mtdparts.c b/common/cmd_mtdparts.c
index 24d27b9..ae5e97d 100644
--- a/common/cmd_mtdparts.c
+++ b/common/cmd_mtdparts.c
@@ -1392,6 +1392,95 @@ static int delete_partition(const char *id)
 	return 1;
 }
 
+#if defined(CONFIG_CMD_MTDPARTS_SPREAD)
+/** Increase the size of the given partition so that it's net size is at least
+ * as large as the size member and such that the next parition would start on a
+ * good blcok if it were adjacent to this partition
+ * @param mtd the mtd device
+ * @param part the partition
+ * @param next_offset pointer to the offset of the next partition after this
+ *                    partition's size has been modified (output)
+ */
+static void spread_partition(struct mtd_info *mtd, struct part_info *part, u32 *next_offset)
+{
+	u32 i, bb_delta = 0;
+
+	for(i = part->offset;
+	    i - bb_delta < part->offset + part->size;
+	    i += mtd->erasesize) {
+		if(mtd->block_isbad(mtd, i))
+			bb_delta += mtd->erasesize;
+	}
+
+	/* Absorb bad blocks immeadiately following this
+	  * partition also into the partition, such that
+	  * the next partition starts with a good block.
+	  */
+	while(i < mtd->size && mtd->block_isbad(mtd, i)) {
+		bb_delta += mtd->erasesize;
+		i += mtd->erasesize;
+	}
+
+	if(part->offset + part->size + bb_delta > mtd->size) {
+		part->size = mtd->size - part->offset - bb_delta;
+		printf("truncated partition %s to %d bytes\n", part->name, part->size);
+	}
+
+	part->size += bb_delta;
+	*next_offset = part->offset + part->size;
+}
+
+/**
+ * Adjust all of the partition sizes, such that all partitions are at least
+ * as big as their mtdparts environment variable sizes and they each start
+ * on a good block.
+ *
+ * @return 0 on success, 1 otherwise
+ */
+static int spread_partitions(void)
+{
+	struct list_head *dentry, *pentry;
+	struct mtd_device *dev;
+	struct part_info *part;
+	struct mtd_info *mtd;
+	int part_num;
+	u32 cur_offs;
+
+	list_for_each(dentry, &devices) {
+		dev = list_entry(dentry, struct mtd_device, link);
+
+		if(get_mtd_info(dev->id->type, dev->id->num, &mtd))
+			return 1;
+	
+		part_num = 0;
+		cur_offs = 0;
+		list_for_each(pentry, &dev->parts) {
+			part = list_entry(pentry, struct part_info, link);
+
+			debug("spread_partitions: device = %s%d, partition %d ="
+			       " (%s) 0x%08x at 0x%08x\n",
+			       MTD_DEV_TYPE(dev->id->type), dev->id->num, part_num,
+			       part->name, part->size, part->offset);
+
+			if(cur_offs > part->offset)
+				part->offset = cur_offs;
+			
+			spread_partition(mtd,part,&cur_offs);
+
+			part_num++;
+		}
+	}
+
+	index_partitions();
+
+	if (generate_mtdparts_save(last_parts, MTDPARTS_MAXLEN) != 0) {
+		printf("generated mtdparts too long, reseting to null\n");
+		return 1;
+	}
+	return 0;
+}
+#endif /* CONFIG_CMD_MTDPARTS_SPREAD */
+
 /**
  * Accept character string describing mtd partitions and call device_parse()
  * for each entry. Add created devices to the global devices list.
@@ -1882,6 +1971,13 @@ int do_mtdparts(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 		return delete_partition(argv[2]);
 	}
 
+#if defined(CONFIG_CMD_MTDPARTS_SPREAD)
+	if((argc == 2) && (strcmp(argv[1], "spread") == 0)) {
+
+		return spread_partitions();
+	}
+#endif /* CONFIG_CMD_MTDPARTS_SPREAD */
+
 	cmd_usage(cmdtp);
 	return 1;
 }
@@ -1906,7 +2002,15 @@ U_BOOT_CMD(
 	"mtdparts add <mtd-dev> <size>[@<offset>] [<name>] [ro]\n"
 	"    - add partition\n"
 	"mtdparts default\n"
-	"    - reset partition table to defaults\n\n"
+	"    - reset partition table to defaults\n"
+#if defined(CONFIG_CMD_MTDPARTS_SPREAD)
+	"mtdparts spread\n"
+	"    - adjust the sizes of the partitions so they are\n"
+	"      at least as big as the mtdparts variable specifies\n"
+	"      and they each start on a good block\n\n"
+#else
+	"\n"
+#endif /* CONFIG_CMD_MTDPARTS_SPREAD */
 	"-----\n\n"
 	"this command uses three environment variables:\n\n"
 	"'partition' - keeps current partition identifier\n\n"
-- 
1.7.0.4