ubi-media.h

基于linux-2.6.28的mtd驱动

/*
 * Copyright (c) International Business Machines Corp., 2006
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Thomas Gleixner
 *          Frank Haverkamp
 *          Oliver Lohmann
 *          Andreas Arnez
 */

/*
 * This file defines the layout of UBI headers and all the other UBI on-flash
 * data structures.
 */

#ifndef __UBI_MEDIA_H__
#define __UBI_MEDIA_H__

#include <asm/byteorder.h>

/* The version of UBI images supported by this implementation */
#define UBI_VERSION 1

/* The highest erase counter value supported by this implementation */
#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF

/* The initial CRC32 value used when calculating CRC checksums */
#define UBI_CRC32_INIT 0xFFFFFFFFU

/* Erase counter header magic number (ASCII "UBI#") */
#define UBI_EC_HDR_MAGIC  0x55424923
/* Volume identifier header magic number (ASCII "UBI!") */
#define UBI_VID_HDR_MAGIC 0x55424921

/*
 * Volume type constants used in the volume identifier header.
 *
 * @UBI_VID_DYNAMIC: dynamic volume
 * @UBI_VID_STATIC: static volume
 */
enum {
	UBI_VID_DYNAMIC = 1,
	UBI_VID_STATIC  = 2
};

/*
 * Volume flags used in the volume table record.
 *
 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
 *
 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
 * table. UBI automatically re-sizes the volume which has this flag and makes
 * the volume to be of largest possible size. This means that if after the
 * initialization UBI finds out that there are available physical eraseblocks
 * present on the device, it automatically appends all of them to the volume
 * (the physical eraseblocks reserved for bad eraseblocks handling and other
 * reserved physical eraseblocks are not taken). So, if there is a volume with
 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
 * eraseblocks will be zero after UBI is loaded, because all of them will be
 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
 * after the volume had been initialized.
 *
 * The auto-resize feature is useful for device production purposes. For
 * example, different NAND flash chips may have different amount of initial bad
 * eraseblocks, depending of particular chip instance. Manufacturers of NAND
 * chips usually guarantee that the amount of initial bad eraseblocks does not
 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
 * flashed to the end devices in production, he does not know the exact amount
 * of good physical eraseblocks the NAND chip on the device will have, but this
 * number is required to calculate the volume sized and put them to the volume
 * table of the UBI image. In this case, one of the volumes (e.g., the one
 * which will store the root file system) is marked as "auto-resizable", and
 * UBI will adjust its size on the first boot if needed.
 *
 * Note, first UBI reserves some amount of physical eraseblocks for bad
 * eraseblock handling, and then re-sizes the volume, not vice-versa. This
 * means that the pool of reserved physical eraseblocks will always be present.
 */
enum {
	UBI_VTBL_AUTORESIZE_FLG = 0x01,
};

/*
 * Compatibility constants used by internal volumes.
 *
 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
 *                     to the flash
 * @UBI_COMPAT_RO: attach this device in read-only mode
 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
 *                       physical eraseblocks, don't allow the wear-leveling
 *                       sub-system to move them
 * @UBI_COMPAT_REJECT: reject this UBI image
 */
enum {
	UBI_COMPAT_DELETE   = 1,
	UBI_COMPAT_RO       = 2,
	UBI_COMPAT_PRESERVE = 4,
	UBI_COMPAT_REJECT   = 5
};

/* Sizes of UBI headers */
#define UBI_EC_HDR_SIZE  sizeof(struct ubi_ec_hdr)
#define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)

/* Sizes of UBI headers without the ending CRC */
#define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(__be32))
#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))

/**
 * struct ubi_ec_hdr - UBI erase counter header.
 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
 * @version: version of UBI implementation which is supposed to accept this
 *           UBI image
 * @padding1: reserved for future, zeroes
 * @ec: the erase counter
 * @vid_hdr_offset: where the VID header starts
 * @data_offset: where the user data start
 * @padding2: reserved for future, zeroes
 * @hdr_crc: erase counter header CRC checksum
 *
 * The erase counter header takes 64 bytes and has a plenty of unused space for
 * future usage. The unused fields are zeroed. The @version field is used to
 * indicate the version of UBI implementation which is supposed to be able to
 * work with this UBI image. If @version is greater then the current UBI
 * version, the image is rejected. This may be useful in future if something
 * is changed radically. This field is duplicated in the volume identifier
 * header.
 *
 * The @vid_hdr_offset and @data_offset fields contain the offset of the the
 * volume identifier header and user data, relative to the beginning of the
 * physical eraseblock. These values have to be the same for all physical
 * eraseblocks.
 */
struct ubi_ec_hdr {
	__be32  magic;
	__u8    version;
	__u8    padding1[3];
	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
	__be32  vid_hdr_offset;
	__be32  data_offset;
	__u8    padding2[36];
	__be32  hdr_crc;
} __attribute__ ((packed));

/**
 * struct ubi_vid_hdr - on-flash UBI volume identifier header.
 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
 * @version: UBI implementation version which is supposed to accept this UBI
 *           image (%UBI_VERSION)
 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
 * @copy_flag: if this logical eraseblock was copied from another physical
 *             eraseblock (for wear-leveling reasons)
 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
 *          %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
 * @vol_id: ID of this volume
 * @lnum: logical eraseblock number
 * @padding1: reserved for future, zeroes
 * @data_size: how many bytes of data this logical eraseblock contains
 * @used_ebs: total number of used logical eraseblocks in this volume
 * @data_pad: how many bytes at the end of this physical eraseblock are not
 *            used
 * @data_crc: CRC checksum of the data stored in this logical eraseblock
 * @padding2: reserved for future, zeroes
 * @sqnum: sequence number
 * @padding3: reserved for future, zeroes
 * @hdr_crc: volume identifier header CRC checksum
 *
 * The @sqnum is the value of the global sequence counter at the time when this
 * VID header was created. The global sequence counter is incremented each time
 * UBI writes a new VID header to the flash, i.e. when it maps a logical
 * eraseblock to a new physical eraseblock. The global sequence counter is an