Subversion Repositories test_project

/*

 * 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. May be included by user-space.

 */

#ifndef __UBI_HEADER_H__

#define __UBI_HEADER_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

};

/*

 * 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 unit 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

 * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be

 * removed, kept only for not breaking older UBI users)

 * @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

 * @padding1: reserved for future, zeroes

 * @sqnum: sequence number

 * @padding2: 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

 * unsigned 64-bit integer and we assume it never overflows. The @sqnum

 * (sequence number) is used to distinguish between older and newer versions of

 * logical eraseblocks.

 *

 * There are 2 situations when there may be more then one physical eraseblock

 * corresponding to the same logical eraseblock, i.e., having the same @vol_id

 * and @lnum values in the volume identifier header. Suppose we have a logical

 * eraseblock L and it is mapped to the physical eraseblock P.

 *

 * 1. Because UBI may erase physical eraseblocks asynchronously, the following

 * situation is possible: L is asynchronously erased, so P is scheduled for

 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,

 * so P1 is written to, then an unclean reboot happens. Result - there are 2

 * physical eraseblocks P and P1 corresponding to the same logical eraseblock

 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the

 * flash.

 *

 * 2. From time to time UBI moves logical eraseblocks to other physical

 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P

 * to P1, and an unclean reboot happens before P is physically erased, there

 * are two physical eraseblocks P and P1 corresponding to L and UBI has to

 * select one of them when the flash is attached. The @sqnum field says which

 * PEB is the original (obviously P will have lower @sqnum) and the copy. But

 * it is not enough to select the physical eraseblock with the higher sequence

 * number, because the unclean reboot could have happen in the middle of the

 * copying process, so the data in P is corrupted. It is also not enough to

 * just select the physical eraseblock with lower sequence number, because the

 * data there may be old (consider a case if more data was added to P1 after

 * the copying). Moreover, the unclean reboot may happen when the erasure of P

 * was just started, so it result in unstable P, which is "mostly" OK, but

 * still has unstable bits.

 *

 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a

 * copy. UBI also calculates data CRC when the data is moved and stores it at

 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical

 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is

 * examined. If it is cleared, the situation* is simple and the newer one is

 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC

 * checksum is correct, this physical eraseblock is selected (P1). Otherwise

 * the older one (P) is selected.

 *

 * Note, there is an obsolete @leb_ver field which was used instead of @sqnum

 * in the past. But it is not used anymore and we keep it in order to be able

 * to deal with old UBI images. It will be removed at some point.

 *

 * There are 2 sorts of volumes in UBI: user volumes and internal volumes.

 * Internal volumes are not seen from outside and are used for various internal

 * UBI purposes. In this implementation there is only one internal volume - the

 * layout volume. Internal volumes are the main mechanism of UBI extensions.

 * For example, in future one may introduce a journal internal volume. Internal

 * volumes have their own reserved range of IDs.

 *

 * The @compat field is only used for internal volumes and contains the "degree

 * of their compatibility". It is always zero for user volumes. This field

 * provides a mechanism to introduce UBI extensions and to be still compatible

 * with older UBI binaries. For example, if someone introduced a journal in

 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the

 * journal volume.  And in this case, older UBI binaries, which know nothing

 * about the journal volume, would just delete this volume and work perfectly

 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image

 * - it just ignores the Ext3fs journal.

 *

 * The @data_crc field contains the CRC checksum of the contents of the logical

 * eraseblock if this is a static volume. In case of dynamic volumes, it does

 * not contain the CRC checksum as a rule. The only exception is when the

 * data of the physical eraseblock was moved by the wear-leveling unit, then

 * the wear-leveling unit calculates the data CRC and stores it in the

 * @data_crc field. And of course, the @copy_flag is %in this case.

 *

 * The @data_size field is used only for static volumes because UBI has to know

 * how many bytes of data are stored in this eraseblock. For dynamic volumes,

 * this field usually contains zero. The only exception is when the data of the

 * physical eraseblock was moved to another physical eraseblock for

 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the

 * contents and uses both @data_crc and @data_size fields. In this case, the

 * @data_size field contains data size.

 *

 * The @used_ebs field is used only for static volumes and indicates how many

 * eraseblocks the data of the volume takes. For dynamic volumes this field is

 * not used and always contains zero.

 *

 * The @data_pad is calculated when volumes are created using the alignment

 * parameter. So, effectively, the @data_pad field reduces the size of logical

 * eraseblocks of this volume. This is very handy when one uses block-oriented

 * software (say, cramfs) on top of the UBI volume.

 */

struct ubi_vid_hdr {

        __be32  magic;

        __u8    version;

        __u8    vol_type;

        __u8    copy_flag;

        __u8    compat;

        __be32  vol_id;

        __be32  lnum;

        __be32  leb_ver; /* obsolete, to be removed, don't use */

        __be32  data_size;

        __be32  used_ebs;

        __be32  data_pad;

        __be32  data_crc;

        __u8    padding1[4];

        __be64  sqnum;

        __u8    padding2[12];

        __be32  hdr_crc;

} __attribute__ ((packed));

/* Internal UBI volumes count */

#define UBI_INT_VOL_COUNT 1

/*

 * Starting ID of internal volumes. There is reserved room for 4096 internal

 * volumes.

 */

#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)

/* The layout volume contains the volume table */

#define UBI_LAYOUT_VOL_ID        UBI_INTERNAL_VOL_START

#define UBI_LAYOUT_VOLUME_EBS    2

#define UBI_LAYOUT_VOLUME_NAME   "layout volume"

#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT

/* The maximum number of volumes per one UBI device */

#define UBI_MAX_VOLUMES 128

/* The maximum volume name length */

#define UBI_VOL_NAME_MAX 127

/* Size of the volume table record */

#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)

/* Size of the volume table record without the ending CRC */

#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))

/**

 * struct ubi_vtbl_record - a record in the volume table.

 * @reserved_pebs: how many physical eraseblocks are reserved for this volume

 * @alignment: volume alignment

 * @data_pad: how many bytes are unused at the end of the each physical

 * eraseblock to satisfy the requested alignment

 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)

 * @upd_marker: if volume update was started but not finished

 * @name_len: volume name length

 * @name: the volume name

 * @padding2: reserved, zeroes

 * @crc: a CRC32 checksum of the record

 *

 * The volume table records are stored in the volume table, which is stored in

 * the layout volume. The layout volume consists of 2 logical eraseblock, each

 * of which contains a copy of the volume table (i.e., the volume table is

 * duplicated). The volume table is an array of &struct ubi_vtbl_record

 * objects indexed by the volume ID.

 *

 * If the size of the logical eraseblock is large enough to fit

 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES

 * records. Otherwise, it contains as many records as it can fit (i.e., size of

 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).

 *

 * The @upd_marker flag is used to implement volume update. It is set to %1

 * before update and set to %0 after the update. So if the update operation was

 * interrupted, UBI knows that the volume is corrupted.

 *

 * The @alignment field is specified when the volume is created and cannot be

 * later changed. It may be useful, for example, when a block-oriented file

 * system works on top of UBI. The @data_pad field is calculated using the

 * logical eraseblock size and @alignment. The alignment must be multiple to the

 * minimal flash I/O unit. If @alignment is 1, all the available space of

 * the physical eraseblocks is used.

 *

 * Empty records contain all zeroes and the CRC checksum of those zeroes.

 */

struct ubi_vtbl_record {

        __be32  reserved_pebs;

        __be32  alignment;

        __be32  data_pad;

        __u8    vol_type;

        __u8    upd_marker;

        __be16  name_len;

        __u8    name[UBI_VOL_NAME_MAX+1];

        __u8    padding2[24];

        __be32  crc;

} __attribute__ ((packed));

#endif /* !__UBI_HEADER_H__ */