libflash/libffs: Rework libffs

This patch attempts a rework of libffs to prepare it for future changes.

Firstly the types are split in two:
  1. Packed, big endian structures used to map exactly how the data is on flash.
  2. CPU endian, sane valued, not packed structures used to manipulate FFS data.

Secondly:
The packed struct can use BE types so that in future tools like sparse can be
run over the code to check for endian conversion bugs.

Thirdly:
defines of sizeof(struct ...) were removed for clarity.

Finally:
For ease of manipulation, the in memory FFS structures contain a linked list of
entries as this will make addition and removal operations much easier.

This patch should be invisible to consumers of libffs.

Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 98 insertions, 57 deletions

diff --git a/libflash/ffs.h b/libflash/ffs.h
index 5cb6778..64e5e6a 100644
--- a/libflash/ffs.h
+++ b/libflash/ffs.h
@@ -25,11 +25,16 @@
 #define __FFS_H__
 
 /* Pull in the correct header depending on what is being built */
-#if defined(__KERNEL__)
+#ifndef __SKIBOOT__
 #include <linux/types.h>
 #else
 #include <stdint.h>
 #endif
+#include <ccan/short_types/short_types.h>
+#include <ccan/endian/endian.h>
+#include <ccan/list/list.h>
+
+#include "libffs.h"
 
 /* The version of this partition implementation */
 #define FFS_VERSION_1	1
@@ -37,44 +42,22 @@
 /* Magic number for the partition header (ASCII 'PART') */
 #define FFS_MAGIC	0x50415254
 
-/* The maximum length of the partition name */
-#define PART_NAME_MAX   15
-
-/*
- * Sizes of the data structures
- */
-#define FFS_HDR_SIZE   sizeof(struct ffs_hdr)
-#define FFS_ENTRY_SIZE sizeof(struct ffs_entry)
-
-/*
- * Sizes of the data structures w/o checksum
- */
-#define FFS_HDR_SIZE_CSUM   (FFS_HDR_SIZE - sizeof(uint32_t))
-#define FFS_ENTRY_SIZE_CSUM (FFS_ENTRY_SIZE - sizeof(uint32_t))
-
 /* pid of logical partitions/containers */
 #define FFS_PID_TOPLEVEL   0xFFFFFFFF
 
 /*
  * Type of image contained w/in partition
  */
-enum type {
+enum ffs_type {
 	FFS_TYPE_DATA      = 1,
 	FFS_TYPE_LOGICAL   = 2,
 	FFS_TYPE_PARTITION = 3,
 };
 
-/*
- * Flag bit definitions
- */
-#define FFS_FLAGS_PROTECTED	0x0001
-#define FFS_FLAGS_U_BOOT_ENV	0x0002
-
-/* Data integrity flags */
-#define FFS_ENRY_INTEG_ECC 0x8000
-
 /**
- * struct ffs_entry_user - User data enties
+ * struct __ffs_entry_user - On flash user data entries
+ *
+ * Represents the on flash layout of FFS structures
  *
  *  @chip:		Chip Select (0,1)
  *  @compressType:	Compression Indication/alg (0=not compressed)
@@ -84,18 +67,22 @@ enum type {
  *  @freeMisc[2]:	Unused Miscellaneious Info
  *  @freeUser[14]:	Unused User Data
  */
-struct ffs_entry_user {
-	uint8_t  chip;
-	uint8_t  compresstype;
-	uint16_t datainteg;
-	uint8_t  vercheck;
-	uint8_t  miscflags;
-	uint8_t  freemisc[2];
-	uint32_t reserved[14];
-};
+struct __ffs_entry_user {
+	uint8_t chip;
+	uint8_t compresstype;
+	be16 datainteg;
+	uint8_t vercheck;
+	uint8_t miscflags;
+	uint8_t freemisc[2];
+	be32 reserved[14];
+} __attribute__ ((packed));
 
 /**
- * struct ffs_entry - Partition entry
+ * struct __ffs_entry - On flash partition entry
+ *
+ * Represents the on flash layout of FFS structures
+ * Note: Unlike the in memory structures base and size of the entry are in
+ * units of block_size and the actual size is in bytes
  *
  * @name:	Opaque null terminated string
  * @base:	Starting offset of partition in flash (in hdr.block_size)
@@ -109,22 +96,54 @@ struct ffs_entry_user {
  * @user:	User data (optional)
  * @checksum:	Partition entry checksum (includes all above)
  */
+struct __ffs_entry {
+	char name[FFS_PART_NAME_MAX + 1];
+	be32 base;
+	be32 size;
+	be32 pid;
+	be32 id;
+	be32 type;
+	be32 flags;
+	be32 actual;
+	be32 resvd[4];
+	struct __ffs_entry_user user;
+	/* The checksum is actually endian agnostic */
+	uint32_t checksum;
+} __attribute__ ((packed));
+
+/**
+ * struct ffs_entry - Partition entry
+ *
+ * Useable in memory representation of a struct __ffs_entry
+ * Note: Unlike the on flash structure, all sizes here are in bytes!
+ *
+ * @name:	Opaque null terminated string
+ * @base:	Starting offset of partition in flash (in bytes)
+ * @size:	Partition size (in bytes)
+ * @actual:	Actual partition size (in bytes)
+ * @pid:	Parent partition entry (FFS_PID_TOPLEVEL for toplevel)
+ * @type:	Describe type of partition
+ * @flags:	Partition attributes (optional)
+ * @user:	User data (optional)
+ */
 struct ffs_entry {
-	char     name[PART_NAME_MAX + 1];
+	char name[FFS_PART_NAME_MAX + 1];
 	uint32_t base;
 	uint32_t size;
+	uint32_t actual;
 	uint32_t pid;
-	uint32_t id;
-	uint32_t type;
+	enum ffs_type type;
 	uint32_t flags;
-	uint32_t actual;
-	uint32_t resvd[4];
 	struct ffs_entry_user user;
-	uint32_t checksum;
-} __attribute__ ((packed));
+	struct list_node list;
+};
+
 
 /**
- * struct ffs_hdr - FSP Flash Structure header
+ * struct __ffs_hdr - On flash FSP Flash Structure header
+ *
+ * Represents the on flash layout of FFS structures
+ * Note: Beware that the size of the partition table is in units of block_size
  *
  * @magic:		Eye catcher/corruption detector
  * @version:		Version of the structure
@@ -133,22 +152,44 @@ struct ffs_entry {
  * @entry_count:	Number of struct ffs_entry elements in @entries array
  * @block_size:		Size of block on device (in bytes)
  * @block_count:	Number of blocks on device
- * @resvd:		Reserved words for future use
+ * @resvd[4]:		Reserved words for future use
  * @checksum:		Header checksum
  * @entries:		Pointer to array of partition entries
  */
-struct ffs_hdr {
-	uint32_t         magic;
-	uint32_t         version;
-	uint32_t         size;
-	uint32_t         entry_size;
-	uint32_t         entry_count;
-	uint32_t         block_size;
-	uint32_t         block_count;
-	uint32_t         resvd[4];
-	uint32_t         checksum;
-	struct ffs_entry entries[];
+struct __ffs_hdr {
+	be32 magic;
+	be32 version;
+	be32 size;
+	be32 entry_size;
+	be32 entry_count;
+	be32 block_size;
+	be32 block_count;
+	be32 resvd[4];
+	/* The checksum is actually endian agnostic */
+	uint32_t checksum;
+	struct __ffs_entry entries[];
 } __attribute__ ((packed));
 
+/**
+ * struct ffs_hdr - FSP Flash Structure header
+ *
+ * Useable in memory representation of a struct __ffs_hdr
+ * Note: All sizes here are in bytes
+ *
+ * @version:		Version of the structure
+ * @size:		Size of partition table (in bytes)
+ * @block_size:		Size of block on device (in bytes)
+ * @block_count:	Number of blocks on device.
+ * @backup		The backup partition
+ * @side		The ffs header for the other side
+ * @entries:		List of partition entries
+ */
+struct ffs_hdr {
+	uint32_t version;
+	uint32_t size;
+	uint32_t block_size;
+	uint32_t block_count;
+	struct list_head entries;
+};
 
 #endif /* __FFS_H__ */