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 (���������������� ����������) 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 */ 55enum { 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 */ 70enum { 71 UBI_COMPAT_DELETE = 1, 72 UBI_COMPAT_RO = 2, 73 UBI_COMPAT_PRESERVE = 4, 74 UBI_COMPAT_REJECT = 5 75}; 76 77/* 78 * ubi16_t/ubi32_t/ubi64_t - 16, 32, and 64-bit integers used in UBI on-flash 79 * data structures. 80 */ 81typedef struct { 82 uint16_t int16; 83} __attribute__ ((packed)) ubi16_t; 84 85typedef struct { 86 uint32_t int32; 87} __attribute__ ((packed)) ubi32_t; 88 89typedef struct { 90 uint64_t int64; 91} __attribute__ ((packed)) ubi64_t; 92 93/* 94 * In this implementation of UBI uses the big-endian format for on-flash 95 * integers. The below are the corresponding conversion macros. 96 */ 97#define cpu_to_ubi16(x) ((ubi16_t){__cpu_to_be16(x)}) 98#define ubi16_to_cpu(x) ((uint16_t)__be16_to_cpu((x).int16)) 99 100#define cpu_to_ubi32(x) ((ubi32_t){__cpu_to_be32(x)}) 101#define ubi32_to_cpu(x) ((uint32_t)__be32_to_cpu((x).int32)) 102 103#define cpu_to_ubi64(x) ((ubi64_t){__cpu_to_be64(x)}) 104#define ubi64_to_cpu(x) ((uint64_t)__be64_to_cpu((x).int64)) 105 106/* Sizes of UBI headers */ 107#define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr) 108#define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr) 109 110/* Sizes of UBI headers without the ending CRC */ 111#define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(ubi32_t)) 112#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(ubi32_t)) 113 114/** 115 * struct ubi_ec_hdr - UBI erase counter header. 116 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC) 117 * @version: version of UBI implementation which is supposed to accept this 118 * UBI image 119 * @padding1: reserved for future, zeroes 120 * @ec: the erase counter 121 * @vid_hdr_offset: where the VID header starts 122 * @data_offset: where the user data start 123 * @padding2: reserved for future, zeroes 124 * @hdr_crc: erase counter header CRC checksum 125 * 126 * The erase counter header takes 64 bytes and has a plenty of unused space for 127 * future usage. The unused fields are zeroed. The @version field is used to 128 * indicate the version of UBI implementation which is supposed to be able to 129 * work with this UBI image. If @version is greater then the current UBI 130 * version, the image is rejected. This may be useful in future if something 131 * is changed radically. This field is duplicated in the volume identifier 132 * header. 133 * 134 * The @vid_hdr_offset and @data_offset fields contain the offset of the the 135 * volume identifier header and user data, relative to the beginning of the 136 * physical eraseblock. These values have to be the same for all physical 137 * eraseblocks. 138 */ 139struct ubi_ec_hdr { 140 ubi32_t magic; 141 uint8_t version; 142 uint8_t padding1[3]; 143 ubi64_t ec; /* Warning: the current limit is 31-bit anyway! */ 144 ubi32_t vid_hdr_offset; 145 ubi32_t data_offset; 146 uint8_t padding2[36]; 147 ubi32_t hdr_crc; 148} __attribute__ ((packed)); 149 150/** 151 * struct ubi_vid_hdr - on-flash UBI volume identifier header. 152 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC) 153 * @version: UBI implementation version which is supposed to accept this UBI 154 * image (%UBI_VERSION) 155 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC) 156 * @copy_flag: if this logical eraseblock was copied from another physical 157 * eraseblock (for wear-leveling reasons) 158 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE, 159 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT) 160 * @vol_id: ID of this volume 161 * @lnum: logical eraseblock number 162 * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be 163 * removed, kept only for not breaking older UBI users) 164 * @data_size: how many bytes of data this logical eraseblock contains 165 * @used_ebs: total number of used logical eraseblocks in this volume 166 * @data_pad: how many bytes at the end of this physical eraseblock are not 167 * used 168 * @data_crc: CRC checksum of the data stored in this logical eraseblock 169 * @padding1: reserved for future, zeroes 170 * @sqnum: sequence number 171 * @padding2: reserved for future, zeroes 172 * @hdr_crc: volume identifier header CRC checksum 173 * 174 * The @sqnum is the value of the global sequence counter at the time when this 175 * VID header was created. The global sequence counter is incremented each time 176 * UBI writes a new VID header to the flash, i.e. when it maps a logical 177 * eraseblock to a new physical eraseblock. The global sequence counter is an 178 * unsigned 64-bit integer and we assume it never overflows. The @sqnum 179 * (sequence number) is used to distinguish between older and newer versions of 180 * logical eraseblocks. 181 * 182 * There are 2 situations when there may be more then one physical eraseblock 183 * corresponding to the same logical eraseblock, i.e., having the same @vol_id 184 * and @lnum values in the volume identifier header. Suppose we have a logical 185 * eraseblock L and it is mapped to the physical eraseblock P. 186 * 187 * 1. Because UBI may erase physical eraseblocks asynchronously, the following 188 * situation is possible: L is asynchronously erased, so P is scheduled for 189 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1, 190 * so P1 is written to, then an unclean reboot happens. Result - there are 2 191 * physical eraseblocks P and P1 corresponding to the same logical eraseblock 192 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the 193 * flash. 194 * 195 * 2. From time to time UBI moves logical eraseblocks to other physical 196 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P 197 * to P1, and an unclean reboot happens before P is physically erased, there 198 * are two physical eraseblocks P and P1 corresponding to L and UBI has to 199 * select one of them when the flash is attached. The @sqnum field says which 200 * PEB is the original (obviously P will have lower @sqnum) and the copy. But 201 * it is not enough to select the physical eraseblock with the higher sequence 202 * number, because the unclean reboot could have happen in the middle of the 203 * copying process, so the data in P is corrupted. It is also not enough to 204 * just select the physical eraseblock with lower sequence number, because the 205 * data there may be old (consider a case if more data was added to P1 after 206 * the copying). Moreover, the unclean reboot may happen when the erasure of P 207 * was just started, so it result in unstable P, which is "mostly" OK, but 208 * still has unstable bits. 209 * 210 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a 211 * copy. UBI also calculates data CRC when the data is moved and stores it at 212 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical 213 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is 214 * examined. If it is cleared, the situation* is simple and the newer one is 215 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC 216 * checksum is correct, this physical eraseblock is selected (P1). Otherwise 217 * the older one (P) is selected. 218 * 219 * Note, there is an obsolete @leb_ver field which was used instead of @sqnum 220 * in the past. But it is not used anymore and we keep it in order to be able 221 * to deal with old UBI images. It will be removed at some point. 222 * 223 * There are 2 sorts of volumes in UBI: user volumes and internal volumes. 224 * Internal volumes are not seen from outside and are used for various internal 225 * UBI purposes. In this implementation there is only one internal volume - the 226 * layout volume. Internal volumes are the main mechanism of UBI extensions. 227 * For example, in future one may introduce a journal internal volume. Internal 228 * volumes have their own reserved range of IDs. 229 * 230 * The @compat field is only used for internal volumes and contains the "degree 231 * of their compatibility". It is always zero for user volumes. This field 232 * provides a mechanism to introduce UBI extensions and to be still compatible 233 * with older UBI binaries. For example, if someone introduced a journal in 234 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the 235 * journal volume. And in this case, older UBI binaries, which know nothing 236 * about the journal volume, would just delete this volume and work perfectly 237 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image 238 * - it just ignores the Ext3fs journal. 239 * 240 * The @data_crc field contains the CRC checksum of the contents of the logical 241 * eraseblock if this is a static volume. In case of dynamic volumes, it does 242 * not contain the CRC checksum as a rule. The only exception is when the 243 * data of the physical eraseblock was moved by the wear-leveling unit, then 244 * the wear-leveling unit calculates the data CRC and stores it in the 245 * @data_crc field. And of course, the @copy_flag is %in this case. 246 * 247 * The @data_size field is used only for static volumes because UBI has to know 248 * how many bytes of data are stored in this eraseblock. For dynamic volumes, 249 * this field usually contains zero. The only exception is when the data of the 250 * physical eraseblock was moved to another physical eraseblock for 251 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the 252 * contents and uses both @data_crc and @data_size fields. In this case, the 253 * @data_size field contains data size. 254 * 255 * The @used_ebs field is used only for static volumes and indicates how many 256 * eraseblocks the data of the volume takes. For dynamic volumes this field is 257 * not used and always contains zero. 258 * 259 * The @data_pad is calculated when volumes are created using the alignment 260 * parameter. So, effectively, the @data_pad field reduces the size of logical 261 * eraseblocks of this volume. This is very handy when one uses block-oriented 262 * software (say, cramfs) on top of the UBI volume. 263 */ 264struct ubi_vid_hdr { 265 ubi32_t magic; 266 uint8_t version; 267 uint8_t vol_type; 268 uint8_t copy_flag; 269 uint8_t compat; 270 ubi32_t vol_id; 271 ubi32_t lnum; 272 ubi32_t leb_ver; /* obsolete, to be removed, don't use */ 273 ubi32_t data_size; 274 ubi32_t used_ebs; 275 ubi32_t data_pad; 276 ubi32_t data_crc; 277 uint8_t padding1[4]; 278 ubi64_t sqnum; 279 uint8_t padding2[12]; 280 ubi32_t hdr_crc; 281} __attribute__ ((packed)); 282 283/* Internal UBI volumes count */ 284#define UBI_INT_VOL_COUNT 1 285 286/* 287 * Starting ID of internal volumes. There is reserved room for 4096 internal 288 * volumes. 289 */ 290#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096) 291 292/* The layout volume contains the volume table */ 293 294#define UBI_LAYOUT_VOL_ID UBI_INTERNAL_VOL_START 295#define UBI_LAYOUT_VOLUME_EBS 2 296#define UBI_LAYOUT_VOLUME_NAME "layout volume" 297#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT 298 299/* The maximum number of volumes per one UBI device */ 300#define UBI_MAX_VOLUMES 128 301 302/* The maximum volume name length */ 303#define UBI_VOL_NAME_MAX 127 304 305/* Size of the volume table record */ 306#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record) 307 308/* Size of the volume table record without the ending CRC */ 309#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(ubi32_t)) 310 311/** 312 * struct ubi_vtbl_record - a record in the volume table. 313 * @reserved_pebs: how many physical eraseblocks are reserved for this volume 314 * @alignment: volume alignment 315 * @data_pad: how many bytes are unused at the end of the each physical 316 * eraseblock to satisfy the requested alignment 317 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME) 318 * @upd_marker: if volume update was started but not finished 319 * @name_len: volume name length 320 * @name: the volume name 321 * @padding2: reserved, zeroes 322 * @crc: a CRC32 checksum of the record 323 * 324 * The volume table records are stored in the volume table, which is stored in 325 * the layout volume. The layout volume consists of 2 logical eraseblock, each 326 * of which contains a copy of the volume table (i.e., the volume table is 327 * duplicated). The volume table is an array of &struct ubi_vtbl_record 328 * objects indexed by the volume ID. 329 * 330 * If the size of the logical eraseblock is large enough to fit 331 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES 332 * records. Otherwise, it contains as many records as it can fit (i.e., size of 333 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)). 334 * 335 * The @upd_marker flag is used to implement volume update. It is set to %1 336 * before update and set to %0 after the update. So if the update operation was 337 * interrupted, UBI knows that the volume is corrupted. 338 * 339 * The @alignment field is specified when the volume is created and cannot be 340 * later changed. It may be useful, for example, when a block-oriented file 341 * system works on top of UBI. The @data_pad field is calculated using the 342 * logical eraseblock size and @alignment. The alignment must be multiple to the 343 * minimal flash I/O unit. If @alignment is 1, all the available space of 344 * the physical eraseblocks is used. 345 * 346 * Empty records contain all zeroes and the CRC checksum of those zeroes. 347 */ 348struct ubi_vtbl_record { 349 ubi32_t reserved_pebs; 350 ubi32_t alignment; 351 ubi32_t data_pad; 352 uint8_t vol_type; 353 uint8_t upd_marker; 354 ubi16_t name_len; 355 uint8_t name[UBI_VOL_NAME_MAX+1]; 356 uint8_t padding2[24]; 357 ubi32_t crc; 358} __attribute__ ((packed)); 359 360#endif /* !__UBI_HEADER_H__ */ 361