Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) International Business Machines Corp., 2006 |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See |
| 12 | * the GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 17 | * |
| 18 | * Authors: Artem Bityutskiy (Битюцкий Артём) |
| 19 | * Thomas Gleixner |
| 20 | * Frank Haverkamp |
| 21 | * Oliver Lohmann |
| 22 | * Andreas Arnez |
| 23 | */ |
| 24 | |
| 25 | /* |
| 26 | * This file defines the layout of UBI headers and all the other UBI on-flash |
| 27 | * data structures. May be included by user-space. |
| 28 | */ |
| 29 | |
| 30 | #ifndef __UBI_HEADER_H__ |
| 31 | #define __UBI_HEADER_H__ |
| 32 | |
| 33 | #include <asm/byteorder.h> |
| 34 | |
| 35 | /* The version of UBI images supported by this implementation */ |
| 36 | #define UBI_VERSION 1 |
| 37 | |
| 38 | /* The highest erase counter value supported by this implementation */ |
| 39 | #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF |
| 40 | |
| 41 | /* The initial CRC32 value used when calculating CRC checksums */ |
| 42 | #define UBI_CRC32_INIT 0xFFFFFFFFU |
| 43 | |
| 44 | /* Erase counter header magic number (ASCII "UBI#") */ |
| 45 | #define UBI_EC_HDR_MAGIC 0x55424923 |
| 46 | /* Volume identifier header magic number (ASCII "UBI!") */ |
| 47 | #define UBI_VID_HDR_MAGIC 0x55424921 |
| 48 | |
| 49 | /* |
| 50 | * Volume type constants used in the volume identifier header. |
| 51 | * |
| 52 | * @UBI_VID_DYNAMIC: dynamic volume |
| 53 | * @UBI_VID_STATIC: static volume |
| 54 | */ |
| 55 | enum { |
| 56 | UBI_VID_DYNAMIC = 1, |
| 57 | UBI_VID_STATIC = 2 |
| 58 | }; |
| 59 | |
| 60 | /* |
| 61 | * Compatibility constants used by internal volumes. |
| 62 | * |
| 63 | * @UBI_COMPAT_DELETE: delete this internal volume before anything is written |
| 64 | * to the flash |
| 65 | * @UBI_COMPAT_RO: attach this device in read-only mode |
| 66 | * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its |
| 67 | * physical eraseblocks, don't allow the wear-leveling unit to move them |
| 68 | * @UBI_COMPAT_REJECT: reject this UBI image |
| 69 | */ |
| 70 | enum { |
| 71 | UBI_COMPAT_DELETE = 1, |
| 72 | UBI_COMPAT_RO = 2, |
| 73 | UBI_COMPAT_PRESERVE = 4, |
| 74 | UBI_COMPAT_REJECT = 5 |
| 75 | }; |
| 76 | |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 77 | /* Sizes of UBI headers */ |
| 78 | #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr) |
| 79 | #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr) |
| 80 | |
| 81 | /* Sizes of UBI headers without the ending CRC */ |
Christoph Hellwig | 3261ebd | 2007-05-21 17:41:46 +0300 | [diff] [blame^] | 82 | #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32)) |
| 83 | #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32)) |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 84 | |
| 85 | /** |
| 86 | * struct ubi_ec_hdr - UBI erase counter header. |
| 87 | * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC) |
| 88 | * @version: version of UBI implementation which is supposed to accept this |
| 89 | * UBI image |
| 90 | * @padding1: reserved for future, zeroes |
| 91 | * @ec: the erase counter |
| 92 | * @vid_hdr_offset: where the VID header starts |
| 93 | * @data_offset: where the user data start |
| 94 | * @padding2: reserved for future, zeroes |
| 95 | * @hdr_crc: erase counter header CRC checksum |
| 96 | * |
| 97 | * The erase counter header takes 64 bytes and has a plenty of unused space for |
| 98 | * future usage. The unused fields are zeroed. The @version field is used to |
| 99 | * indicate the version of UBI implementation which is supposed to be able to |
| 100 | * work with this UBI image. If @version is greater then the current UBI |
| 101 | * version, the image is rejected. This may be useful in future if something |
| 102 | * is changed radically. This field is duplicated in the volume identifier |
| 103 | * header. |
| 104 | * |
| 105 | * The @vid_hdr_offset and @data_offset fields contain the offset of the the |
| 106 | * volume identifier header and user data, relative to the beginning of the |
| 107 | * physical eraseblock. These values have to be the same for all physical |
| 108 | * eraseblocks. |
| 109 | */ |
| 110 | struct ubi_ec_hdr { |
Christoph Hellwig | 3261ebd | 2007-05-21 17:41:46 +0300 | [diff] [blame^] | 111 | __be32 magic; |
| 112 | __u8 version; |
| 113 | __u8 padding1[3]; |
| 114 | __be64 ec; /* Warning: the current limit is 31-bit anyway! */ |
| 115 | __be32 vid_hdr_offset; |
| 116 | __be32 data_offset; |
| 117 | __u8 padding2[36]; |
| 118 | __be32 hdr_crc; |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 119 | } __attribute__ ((packed)); |
| 120 | |
| 121 | /** |
| 122 | * struct ubi_vid_hdr - on-flash UBI volume identifier header. |
| 123 | * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC) |
| 124 | * @version: UBI implementation version which is supposed to accept this UBI |
| 125 | * image (%UBI_VERSION) |
| 126 | * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC) |
| 127 | * @copy_flag: if this logical eraseblock was copied from another physical |
| 128 | * eraseblock (for wear-leveling reasons) |
| 129 | * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE, |
| 130 | * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT) |
| 131 | * @vol_id: ID of this volume |
| 132 | * @lnum: logical eraseblock number |
| 133 | * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be |
| 134 | * removed, kept only for not breaking older UBI users) |
| 135 | * @data_size: how many bytes of data this logical eraseblock contains |
| 136 | * @used_ebs: total number of used logical eraseblocks in this volume |
| 137 | * @data_pad: how many bytes at the end of this physical eraseblock are not |
| 138 | * used |
| 139 | * @data_crc: CRC checksum of the data stored in this logical eraseblock |
| 140 | * @padding1: reserved for future, zeroes |
| 141 | * @sqnum: sequence number |
| 142 | * @padding2: reserved for future, zeroes |
| 143 | * @hdr_crc: volume identifier header CRC checksum |
| 144 | * |
| 145 | * The @sqnum is the value of the global sequence counter at the time when this |
| 146 | * VID header was created. The global sequence counter is incremented each time |
| 147 | * UBI writes a new VID header to the flash, i.e. when it maps a logical |
| 148 | * eraseblock to a new physical eraseblock. The global sequence counter is an |
| 149 | * unsigned 64-bit integer and we assume it never overflows. The @sqnum |
| 150 | * (sequence number) is used to distinguish between older and newer versions of |
| 151 | * logical eraseblocks. |
| 152 | * |
| 153 | * There are 2 situations when there may be more then one physical eraseblock |
| 154 | * corresponding to the same logical eraseblock, i.e., having the same @vol_id |
| 155 | * and @lnum values in the volume identifier header. Suppose we have a logical |
| 156 | * eraseblock L and it is mapped to the physical eraseblock P. |
| 157 | * |
| 158 | * 1. Because UBI may erase physical eraseblocks asynchronously, the following |
| 159 | * situation is possible: L is asynchronously erased, so P is scheduled for |
| 160 | * erasure, then L is written to,i.e. mapped to another physical eraseblock P1, |
| 161 | * so P1 is written to, then an unclean reboot happens. Result - there are 2 |
| 162 | * physical eraseblocks P and P1 corresponding to the same logical eraseblock |
| 163 | * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the |
| 164 | * flash. |
| 165 | * |
| 166 | * 2. From time to time UBI moves logical eraseblocks to other physical |
| 167 | * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P |
| 168 | * to P1, and an unclean reboot happens before P is physically erased, there |
| 169 | * are two physical eraseblocks P and P1 corresponding to L and UBI has to |
| 170 | * select one of them when the flash is attached. The @sqnum field says which |
| 171 | * PEB is the original (obviously P will have lower @sqnum) and the copy. But |
| 172 | * it is not enough to select the physical eraseblock with the higher sequence |
| 173 | * number, because the unclean reboot could have happen in the middle of the |
| 174 | * copying process, so the data in P is corrupted. It is also not enough to |
| 175 | * just select the physical eraseblock with lower sequence number, because the |
| 176 | * data there may be old (consider a case if more data was added to P1 after |
| 177 | * the copying). Moreover, the unclean reboot may happen when the erasure of P |
| 178 | * was just started, so it result in unstable P, which is "mostly" OK, but |
| 179 | * still has unstable bits. |
| 180 | * |
| 181 | * UBI uses the @copy_flag field to indicate that this logical eraseblock is a |
| 182 | * copy. UBI also calculates data CRC when the data is moved and stores it at |
| 183 | * the @data_crc field of the copy (P1). So when UBI needs to pick one physical |
| 184 | * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is |
| 185 | * examined. If it is cleared, the situation* is simple and the newer one is |
| 186 | * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC |
| 187 | * checksum is correct, this physical eraseblock is selected (P1). Otherwise |
| 188 | * the older one (P) is selected. |
| 189 | * |
| 190 | * Note, there is an obsolete @leb_ver field which was used instead of @sqnum |
| 191 | * in the past. But it is not used anymore and we keep it in order to be able |
| 192 | * to deal with old UBI images. It will be removed at some point. |
| 193 | * |
| 194 | * There are 2 sorts of volumes in UBI: user volumes and internal volumes. |
| 195 | * Internal volumes are not seen from outside and are used for various internal |
| 196 | * UBI purposes. In this implementation there is only one internal volume - the |
| 197 | * layout volume. Internal volumes are the main mechanism of UBI extensions. |
| 198 | * For example, in future one may introduce a journal internal volume. Internal |
| 199 | * volumes have their own reserved range of IDs. |
| 200 | * |
| 201 | * The @compat field is only used for internal volumes and contains the "degree |
| 202 | * of their compatibility". It is always zero for user volumes. This field |
| 203 | * provides a mechanism to introduce UBI extensions and to be still compatible |
| 204 | * with older UBI binaries. For example, if someone introduced a journal in |
| 205 | * future, he would probably use %UBI_COMPAT_DELETE compatibility for the |
| 206 | * journal volume. And in this case, older UBI binaries, which know nothing |
| 207 | * about the journal volume, would just delete this volume and work perfectly |
| 208 | * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image |
| 209 | * - it just ignores the Ext3fs journal. |
| 210 | * |
| 211 | * The @data_crc field contains the CRC checksum of the contents of the logical |
| 212 | * eraseblock if this is a static volume. In case of dynamic volumes, it does |
| 213 | * not contain the CRC checksum as a rule. The only exception is when the |
| 214 | * data of the physical eraseblock was moved by the wear-leveling unit, then |
| 215 | * the wear-leveling unit calculates the data CRC and stores it in the |
| 216 | * @data_crc field. And of course, the @copy_flag is %in this case. |
| 217 | * |
| 218 | * The @data_size field is used only for static volumes because UBI has to know |
| 219 | * how many bytes of data are stored in this eraseblock. For dynamic volumes, |
| 220 | * this field usually contains zero. The only exception is when the data of the |
| 221 | * physical eraseblock was moved to another physical eraseblock for |
| 222 | * wear-leveling reasons. In this case, UBI calculates CRC checksum of the |
| 223 | * contents and uses both @data_crc and @data_size fields. In this case, the |
| 224 | * @data_size field contains data size. |
| 225 | * |
| 226 | * The @used_ebs field is used only for static volumes and indicates how many |
| 227 | * eraseblocks the data of the volume takes. For dynamic volumes this field is |
| 228 | * not used and always contains zero. |
| 229 | * |
| 230 | * The @data_pad is calculated when volumes are created using the alignment |
| 231 | * parameter. So, effectively, the @data_pad field reduces the size of logical |
| 232 | * eraseblocks of this volume. This is very handy when one uses block-oriented |
| 233 | * software (say, cramfs) on top of the UBI volume. |
| 234 | */ |
| 235 | struct ubi_vid_hdr { |
Christoph Hellwig | 3261ebd | 2007-05-21 17:41:46 +0300 | [diff] [blame^] | 236 | __be32 magic; |
| 237 | __u8 version; |
| 238 | __u8 vol_type; |
| 239 | __u8 copy_flag; |
| 240 | __u8 compat; |
| 241 | __be32 vol_id; |
| 242 | __be32 lnum; |
| 243 | __be32 leb_ver; /* obsolete, to be removed, don't use */ |
| 244 | __be32 data_size; |
| 245 | __be32 used_ebs; |
| 246 | __be32 data_pad; |
| 247 | __be32 data_crc; |
| 248 | __u8 padding1[4]; |
| 249 | __be64 sqnum; |
| 250 | __u8 padding2[12]; |
| 251 | __be32 hdr_crc; |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 252 | } __attribute__ ((packed)); |
| 253 | |
| 254 | /* Internal UBI volumes count */ |
| 255 | #define UBI_INT_VOL_COUNT 1 |
| 256 | |
| 257 | /* |
| 258 | * Starting ID of internal volumes. There is reserved room for 4096 internal |
| 259 | * volumes. |
| 260 | */ |
| 261 | #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096) |
| 262 | |
| 263 | /* The layout volume contains the volume table */ |
| 264 | |
| 265 | #define UBI_LAYOUT_VOL_ID UBI_INTERNAL_VOL_START |
| 266 | #define UBI_LAYOUT_VOLUME_EBS 2 |
| 267 | #define UBI_LAYOUT_VOLUME_NAME "layout volume" |
| 268 | #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT |
| 269 | |
| 270 | /* The maximum number of volumes per one UBI device */ |
| 271 | #define UBI_MAX_VOLUMES 128 |
| 272 | |
| 273 | /* The maximum volume name length */ |
| 274 | #define UBI_VOL_NAME_MAX 127 |
| 275 | |
| 276 | /* Size of the volume table record */ |
| 277 | #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record) |
| 278 | |
| 279 | /* Size of the volume table record without the ending CRC */ |
Christoph Hellwig | 3261ebd | 2007-05-21 17:41:46 +0300 | [diff] [blame^] | 280 | #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32)) |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 281 | |
| 282 | /** |
| 283 | * struct ubi_vtbl_record - a record in the volume table. |
| 284 | * @reserved_pebs: how many physical eraseblocks are reserved for this volume |
| 285 | * @alignment: volume alignment |
| 286 | * @data_pad: how many bytes are unused at the end of the each physical |
| 287 | * eraseblock to satisfy the requested alignment |
| 288 | * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME) |
| 289 | * @upd_marker: if volume update was started but not finished |
| 290 | * @name_len: volume name length |
| 291 | * @name: the volume name |
| 292 | * @padding2: reserved, zeroes |
| 293 | * @crc: a CRC32 checksum of the record |
| 294 | * |
| 295 | * The volume table records are stored in the volume table, which is stored in |
| 296 | * the layout volume. The layout volume consists of 2 logical eraseblock, each |
| 297 | * of which contains a copy of the volume table (i.e., the volume table is |
| 298 | * duplicated). The volume table is an array of &struct ubi_vtbl_record |
| 299 | * objects indexed by the volume ID. |
| 300 | * |
| 301 | * If the size of the logical eraseblock is large enough to fit |
| 302 | * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES |
| 303 | * records. Otherwise, it contains as many records as it can fit (i.e., size of |
| 304 | * logical eraseblock divided by sizeof(struct ubi_vtbl_record)). |
| 305 | * |
| 306 | * The @upd_marker flag is used to implement volume update. It is set to %1 |
| 307 | * before update and set to %0 after the update. So if the update operation was |
| 308 | * interrupted, UBI knows that the volume is corrupted. |
| 309 | * |
| 310 | * The @alignment field is specified when the volume is created and cannot be |
| 311 | * later changed. It may be useful, for example, when a block-oriented file |
| 312 | * system works on top of UBI. The @data_pad field is calculated using the |
| 313 | * logical eraseblock size and @alignment. The alignment must be multiple to the |
| 314 | * minimal flash I/O unit. If @alignment is 1, all the available space of |
| 315 | * the physical eraseblocks is used. |
| 316 | * |
| 317 | * Empty records contain all zeroes and the CRC checksum of those zeroes. |
| 318 | */ |
| 319 | struct ubi_vtbl_record { |
Christoph Hellwig | 3261ebd | 2007-05-21 17:41:46 +0300 | [diff] [blame^] | 320 | __be32 reserved_pebs; |
| 321 | __be32 alignment; |
| 322 | __be32 data_pad; |
| 323 | __u8 vol_type; |
| 324 | __u8 upd_marker; |
| 325 | __be16 name_len; |
| 326 | __u8 name[UBI_VOL_NAME_MAX+1]; |
| 327 | __u8 padding2[24]; |
| 328 | __be32 crc; |
Artem B. Bityutskiy | 801c135 | 2006-06-27 12:22:22 +0400 | [diff] [blame] | 329 | } __attribute__ ((packed)); |
| 330 | |
| 331 | #endif /* !__UBI_HEADER_H__ */ |