| /* |
| * 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__ */ |
