CVS: blob/include/blob partition.h,1.2,1.3

[Erik M. <er...@us...>]

Update of /cvsroot/blob/blob/include/blob
In directory usw-pr-cvs1:/tmp/cvs-serv16728/include/blob

Modified Files:
	partition.h 
Log Message:
The new partition table code, initial part.
Next on the list are functions to manipulate the table.


Index: partition.h
===================================================================
RCS file: /cvsroot/blob/blob/include/blob/partition.h,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -d -r1.2 -r1.3
--- partition.h	26 Dec 2001 23:38:36 -0000	1.2
+++ partition.h	13 Feb 2002 00:19:57 -0000	1.3
@@ -1,7 +1,7 @@
 /*
  * partition.h: flash paritioning
  *
- * Copyright (C) 2001  Erik Mouw (J.A...@it...)
+ * Copyright (C) 2001 2002  Erik Mouw (J.A...@it...)
  *
  * $Id$
  *
@@ -29,30 +29,89 @@
 
 #include <blob/types.h>
 
-#define PART_PARTITION_NAMELEN	(32)
+/* A partition table can contain three types of entries:
+ * - The last entry
+ * - A valid entry
+ * - An invalid entry
+ *
+ * A last entry can be changed into a valid entry by changing the
+ * second last bit (with mask 0x00000002) from 1 to 0, or into an
+ * invalid entry by changing the last two bits (with mask 0x00000003)
+ * from 1 to 0. By doing it like this we can avoid erasing a flash
+ * block.
+ *
+ * Flash chips wear from erase operations (that's why flash lifetime
+ * is specified in erase cycles), so we try to limit the number of
+ * erase operations. Luckily the flash helps us a little bit with
+ * this, because it only allows you to change a '1' bit into a '0'
+ * during a write operation. This means that 0xffff can be changed
+ * into 0x1010, and 0x1010 into 0x0000, but 0x0000 can't be changed
+ * into anything else anymore because there are no '1' bits left.
+ *
+ * The magic values have been carefully choosen to allow changing a
+ * partition entry without having to erase the flash. For a "last"
+ * entry, it is best to keep all other fields except the magic
+ * unitialised: chances are high that the other fields are still at
+ * 0xffffffff so we can reuse them when we change the partition type.
+ */
+
+#define BLOB_PART_LAST_MAGIC	(0x42504533) /* BPE3, Blob Partition Entry 3 */
+#define BLOB_PART_VALID_MAGIC	(0x42504531) /* BPE1, Blob Partition Entry 1 */
+#define BLOB_PART_INVALID_MAGIC	(0x42504530) /* BPE0, Blob Partition Entry 0 */
+#define BLOB_PART_NAMELEN	(32)
+
 
 typedef struct {
-	u32 offset;		/* offset wrt start of flash */
-	u32 size;		/* partition size */
+	/* generic (i.e.: blob independent) data */
+	u32 magic;		/* magic value */
+	u32 next;		/* offset (in bytes) to next partition entry */
+	u32 offset;		/* offset (in bytes) wrt start of flash */
+	u32 size;		/* partition size (in bytes) */
+	char name[BLOB_PART_NAMELEN];
+
+	/* blob specific items, can be changed for other bootloaders */
+	u32 flags;		/* blob specific flags */
 	u32 mem_base;		/* load address in RAM */
 	u32 entry_point;	/* entry point in RAM */
-	u32 flags;
-	char name[PART_PARTITION_NAMELEN];
-} partition_t;
+} blob_partition_t;
 
-#define PART_VALID	(1<<0)
-#define PART_LOAD	(1<<1)
-#define PART_EXPAND	(1<<2)
+#define BLOB_PART_FLAG_PTABLE	(1<<0) /* contains a partition table */
+#define BLOB_PART_FLAG_LOAD	(1<<1) /* load partition into RAM */
+#define BLOB_PART_FLAG_EXEC	(1<<2) /* partition/target is executable */
+#define BLOB_PART_FLAG_JFFS2	(1<<3) /* contains a JFFS2 */
+#define BLOB_PART_FLAG_CRAMFS	(1<<4) /* contains a cramfs */
 
 
-#define PART_MAGIC (0x50727420)		/* "Prt " */
-#define PART_MAX_PARTITIONS (16)	/* 16 partitions ought to be enough */
+/* A partition table is marked with a special entry that marks the
+ * start of the table.
+ *
+ * There are two kinds of blob partition tables: the first one is the
+ * regular partition table that can be changed by the bootloader. The
+ * second one is a default partition table that can be put into the
+ * bootloader binary so it can avoid to waste a flash block for the
+ * partition table. The partition table parser first tries to find a
+ * regular partition table and will fall back on the default table if
+ * it can't find one.
+ *
+ * A partition table entry point has to specify the total size of the
+ * flash (in the size member), and the offset has to specify the
+ * absolute base address.
+ */
 
-typedef struct {
-	int magic;
-	int numpartitions;
-	partition_t partition[PART_MAX_PARTITIONS];
-} partition_table_t;
+#define BLOB_FLASH_PART_TABLE_MAGIC	(0x42465054) /* BFPT, Blob Flash
+						      * Partition Table */
+#define BLOB_DEFAULT_PART_TABLE_MAGIC	(0x42445054) /* BDPT, Blob Default
+						      * Partition Table */
+#define BLOB_COPY_PART_TABLE_MAGIC	(0x42435054) /* BCPT, Blob Copy
+						      * Partition Table */
+
+
+
+
+/* flash functions */
+
+extern const blob_partition_t *default_partition_table;
+extern blob_partition_t *flash_partition_table;