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Diffstat (limited to 'include/mtd/ubi-header.h')
| -rw-r--r-- | include/mtd/ubi-header.h | 390 |
1 files changed, 390 insertions, 0 deletions
diff --git a/include/mtd/ubi-header.h b/include/mtd/ubi-header.h new file mode 100644 index 0000000..1b325a1 --- /dev/null +++ b/include/mtd/ubi-header.h @@ -0,0 +1,390 @@ +/* + * 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 B. Bityutskiy + * 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_HEADER_H__ +#define __UBI_HEADER_H__ + +#include <asm/byteorder.h> + +/* The version of this UBI implementation */ +#define UBI_VERSION 1 + +/* The highest erase counter value supported by this implementation of UBI */ +#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF + +/* The initial CRC32 value used when calculating CRC checksums */ +#define UBI_CRC32_INIT 0xFFFFFFFFU + +/** + * Magic numbers of the UBI headers. + * + * @UBI_EC_HDR_MAGIC: erase counter header magic number (ASCII "UBI#") + * @UBI_VID_HDR_MAGIC: volume identifier header magic number (ASCII "UBI!") + */ +enum { + UBI_EC_HDR_MAGIC = 0x55424923, + UBI_VID_HDR_MAGIC = 0x55424921 +}; + +/** + * Molume type constants used in volume identifier headers. + * + * @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_IGNORE: ignore this internal volume, but the UBI wear-leveling + * unit may still move these logical eraseblocks to ensure wear-leveling + * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its + * physical eraseblocks, don't even 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_IGNORE = 3, + UBI_COMPAT_PRESERVE = 4, + UBI_COMPAT_REJECT = 5 +}; + +/* + * ubi16_t/ubi32_t/ubi64_t - 16, 32, and 64-bit integers used in UBI on-flash + * data structures. + */ +typedef struct { + uint16_t int16; +} __attribute__ ((packed)) ubi16_t; + +typedef struct { + uint32_t int32; +} __attribute__ ((packed)) ubi32_t; + +typedef struct { + uint64_t int64; +} __attribute__ ((packed)) ubi64_t; + +/* + * In this implementation UBI uses the big-endian format for on-flash integers. + * The below are the corresponding endianess conversion macros. + */ +#define cpu_to_ubi16(x) ((ubi16_t){__cpu_to_be16(x)}) +#define ubi16_to_cpu(x) ((uint16_t)__be16_to_cpu((x).int16)) + +#define cpu_to_ubi32(x) ((ubi32_t){__cpu_to_be32(x)}) +#define ubi32_to_cpu(x) ((uint32_t)__be32_to_cpu((x).int32)) + +#define cpu_to_ubi64(x) ((ubi64_t){__cpu_to_be64(x)}) +#define ubi64_to_cpu(x) ((uint64_t)__be64_to_cpu((x).int64)) + +/* + * 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(ubi32_t)) +#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(ubi32_t)) + +/* + * How much private data may internal volumes store in the VID header. + */ +#define UBI_VID_HDR_IVOL_DATA_SIZE 12 + +/** + * struct ubi_ec_hdr - UBI erase counter header. + * + * @magic: the erase counter header magic number (%UBI_EC_HDR_MAGIC) + * @version: the version of UBI implementation which is supposed to accept this + * UBI image (%UBI_VERSION) + * @padding1: reserved for future, zeroes + * @ec: the erase counter + * @vid_hdr_offset: where the VID header begins + * @data_offset: where the user data begins + * @padding2: reserved for future, zeroes + * @hdr_crc: the 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 rejecter. 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 + * eraseblock. These values have to be the same for all eraseblocks. + */ +struct ubi_ec_hdr { + ubi32_t magic; + uint8_t version; + uint8_t padding1[3]; + ubi64_t ec; /* Warning: the current limit is 31-bit anyway! */ + ubi32_t vid_hdr_offset; + ubi32_t data_offset; + uint8_t padding2[36]; + ubi32_t 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: a flag indicating if this physical eraseblock was created by + * means of copying an original physical eraseblock to ensure wear-leveling. + * @compat: compatibility of this volume (%UBI_COMPAT_DELETE, + * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT) + * @vol_id: volume ID + * @lnum: logical eraseblock number + * @leb_ver: eraseblock copy number + * @data_size: how many bytes of data this eraseblock contains. + * @used_ebs: total number of used logical eraseblocks in this volume + * @data_pad: how many bytes at the end of this eraseblock are not used + * @data_crc: CRC checksum of data containing in this eraseblock + * @padding1: reserved for future, zeroes + * @ivol_data: private data of internal volumes + * @hdr_crc: volume identifier header CRC checksum + * + * The @leb_ver and the @copy_flag fields are used to distinguish between older + * and newer copies of logical eraseblocks, as well as to guarantee robustness + * to unclean reboots. As UBI erases logical eraseblocks asynchronously, it has + * to distinguish between older and newer copies of eraseblocks. This is done + * using the @version field. On the other hand, when UBI moves an eraseblock, + * its version is also increased and the @copy_flag is set to 1. Additionally, + * when moving eraseblocks, UBI calculates data CRC and stores it in the + * @data_crc field, even for dynamic volumes. + * + * Thus, if there are 2 eraseblocks of the same volume and logical number, UBI + * uses the following algorithm to pick one of them. It first picks the one + * with larger version (say, A). If @copy_flag is not set, then A is picked. If + * @copy_flag is set, UBI checks the CRC of the eraseblock (@data_crc). This is + * needed to ensure that copying was finished. If the CRC is all right, A is + * picked. If not, the older eraseblock is picked. + * + * Note, the @leb_ver field may overflow. Thus, if you have 2 versions A and B, + * then A > B if abs(A-B) < 0x7FFFFFFF, and A < B otherwise. + * + * There are 2 sorts of volumes in UBI: user volumes and internal volumes. + * Internal volumes are not seen from outside and are used for different + * internal UBI purposes. In this implementation there are only two internal + * volumes: the layout volume and the update volume. Internal volumes are the + * main mechanism of UBI extensions. For example, in future one may introduce a + * journal internal volume. + * + * The @compat field is only used for internal volumes and contains the degree + * of their compatibility. This field 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 an + * journal internal volume in future, he would probably use %UBI_COMPAT_DELETE + * compatibility. And in this case, older UBI binaries, which know nothing + * about the journal volume, would just delete this and work perfectly fine. + * This is somewhat 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 + * logical eraseblock was moved by the wear-leveling unit, then the + * wear-leveling unit calculates the eraseblocks' CRC and stores it at + * @data_crc. + * + * The @data_size field is always used for static volumes because we want to + * know about how many bytes of data are stored in this eraseblock. For + * dynamic eraseblocks, this field usually contains zero. The only exception is + * when the logical eraseblock is moved to another physical eraseblock due to + * 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 the size of logical eraseblock of this volume + * (which may vary owing to @alignment). + * + * 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. + * + * The @ivol_data contains private data of internal volumes. This might be very + * handy to store data in the VID header, not in the eraseblock's contents. For + * example it may make life of simple boot-loaders easier. The @ivol_data field + * contains zeroes for user volumes. + */ +struct ubi_vid_hdr { + ubi32_t magic; + uint8_t version; + uint8_t vol_type; + uint8_t copy_flag; + uint8_t compat; + ubi32_t vol_id; + ubi32_t lnum; + ubi32_t leb_ver; + ubi32_t data_size; + ubi32_t used_ebs; + ubi32_t data_pad; + ubi32_t data_crc; + uint8_t padding1[12]; + uint8_t ivol_data[UBI_VID_HDR_IVOL_DATA_SIZE]; + ubi32_t hdr_crc; +} __attribute__ ((packed)); + +/** + * struct ubi_vid_hdr_upd_vol - private data of the update internal volume + * stored in volume identifier headers. + * + * @vol_id: volume ID of the volume under update + * @padding: zeroes + */ +struct ubi_vid_hdr_upd_vol { + ubi32_t vol_id; + uint8_t padding[UBI_VID_HDR_IVOL_DATA_SIZE - 4]; +} __attribute__ ((packed)); + +/* + * Count of internal UBI volumes. + */ +#define UBI_INT_VOL_COUNT 2 + +/* + * Internal volume IDs start from this digit. There is a reserved room for 4096 + * internal volumes. + */ +#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096) + +/** + * enum ubi_internal_volume_numbers - volume IDs of internal UBI volumes. + * + * %UBI_LAYOUT_VOL_ID: volume ID of the layout volume + * %UBI_UPDATE_VOL_ID: volume ID of the update volume + */ +enum ubi_internal_volume_ids { + UBI_LAYOUT_VOL_ID = UBI_INTERNAL_VOL_START, + UBI_UPDATE_VOL_ID = UBI_INTERNAL_VOL_START + 1 +}; + +/* + * Number of logical eraseblocks reserved for internal volumes. + */ +#define UBI_LAYOUT_VOLUME_EBS 2 +#define UBI_UPDATE_VOLUME_EBS 1 + +/* + * Names of internal volumes + */ +#define UBI_LAYOUT_VOLUME_NAME "The layout volume" +#define UBI_UPDATE_VOLUME_NAME "The update volume" + +/* + * Compatibility flags of internal volumes. + */ +#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT +#define UBI_UPDATE_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 volume table records. + */ +#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vol_tbl_record) + +/* + * Size of volume table records without the ending CRC. + */ +#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(ubi32_t)) + +/** + * struct ubi_vol_tbl_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 not used at the end of the eraseblocks to + * satisfy the requested alignment + * @padding1: reserved, zeroes + * @name_len: the volume name length + * @name: the volume name + * @padding2: reserved, zeroes + * @crc: a CRC32 checksum of the record + * + * The layout volume consists of 2 logical eraseblock, each of which contains + * the volume table (i.e., the volume table is duplicated). The volume table is + * an array of &struct ubi_vol_tbl_record objects indexed by the volume ID. + * + * If the size of the logical eraseblock is large enough to fit + * %UBI_MAX_VOLUMES, the volume table contains %UBI_MAX_VOLUMES records. + * Otherwise, it contains as much records as can be fit (i.e., size of logical + * eraseblock divided by sizeof(struct ubi_vol_tbl_record)). + * + * 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 + * eraseblocks is used. + * + * Empty records contain all zeroes and the CRC checksum of those zeroes. + */ +struct ubi_vol_tbl_record { + ubi32_t reserved_pebs; + ubi32_t alignment; + ubi32_t data_pad; + uint8_t vol_type; + uint8_t padding1; + ubi16_t name_len; + uint8_t name[UBI_VOL_NAME_MAX + 1]; + uint8_t padding2[24]; + ubi32_t crc; +} __attribute__ ((packed)); + +#endif /* !__UBI_HEADER_H__ */ |