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. 28 */ 29 30 #ifndef __UBI_MEDIA_H__ 31 #define __UBI_MEDIA_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 * Volume flags used in the volume table record. 62 * 63 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume 64 * 65 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume 66 * table. UBI automatically re-sizes the volume which has this flag and makes 67 * the volume to be of largest possible size. This means that if after the 68 * initialization UBI finds out that there are available physical eraseblocks 69 * present on the device, it automatically appends all of them to the volume 70 * (the physical eraseblocks reserved for bad eraseblocks handling and other 71 * reserved physical eraseblocks are not taken). So, if there is a volume with 72 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical 73 * eraseblocks will be zero after UBI is loaded, because all of them will be 74 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared 75 * after the volume had been initialized. 76 * 77 * The auto-resize feature is useful for device production purposes. For 78 * example, different NAND flash chips may have different amount of initial bad 79 * eraseblocks, depending of particular chip instance. Manufacturers of NAND 80 * chips usually guarantee that the amount of initial bad eraseblocks does not 81 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be 82 * flashed to the end devices in production, he does not know the exact amount 83 * of good physical eraseblocks the NAND chip on the device will have, but this 84 * number is required to calculate the volume sized and put them to the volume 85 * table of the UBI image. In this case, one of the volumes (e.g., the one 86 * which will store the root file system) is marked as "auto-resizable", and 87 * UBI will adjust its size on the first boot if needed. 88 * 89 * Note, first UBI reserves some amount of physical eraseblocks for bad 90 * eraseblock handling, and then re-sizes the volume, not vice-versa. This 91 * means that the pool of reserved physical eraseblocks will always be present. 92 */ 93 enum { 94 UBI_VTBL_AUTORESIZE_FLG = 0x01, 95 }; 96 97 /* 98 * Compatibility constants used by internal volumes. 99 * 100 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written 101 * to the flash 102 * @UBI_COMPAT_RO: attach this device in read-only mode 103 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its 104 * physical eraseblocks, don't allow the wear-leveling unit to move them 105 * @UBI_COMPAT_REJECT: reject this UBI image 106 */ 107 enum { 108 UBI_COMPAT_DELETE = 1, 109 UBI_COMPAT_RO = 2, 110 UBI_COMPAT_PRESERVE = 4, 111 UBI_COMPAT_REJECT = 5 112 }; 113 114 /* Sizes of UBI headers */ 115 #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr) 116 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr) 117 118 /* Sizes of UBI headers without the ending CRC */ 119 #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32)) 120 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32)) 121 122 /** 123 * struct ubi_ec_hdr - UBI erase counter header. 124 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC) 125 * @version: version of UBI implementation which is supposed to accept this 126 * UBI image 127 * @padding1: reserved for future, zeroes 128 * @ec: the erase counter 129 * @vid_hdr_offset: where the VID header starts 130 * @data_offset: where the user data start 131 * @padding2: reserved for future, zeroes 132 * @hdr_crc: erase counter header CRC checksum 133 * 134 * The erase counter header takes 64 bytes and has a plenty of unused space for 135 * future usage. The unused fields are zeroed. The @version field is used to 136 * indicate the version of UBI implementation which is supposed to be able to 137 * work with this UBI image. If @version is greater then the current UBI 138 * version, the image is rejected. This may be useful in future if something 139 * is changed radically. This field is duplicated in the volume identifier 140 * header. 141 * 142 * The @vid_hdr_offset and @data_offset fields contain the offset of the the 143 * volume identifier header and user data, relative to the beginning of the 144 * physical eraseblock. These values have to be the same for all physical 145 * eraseblocks. 146 */ 147 struct ubi_ec_hdr { 148 __be32 magic; 149 __u8 version; 150 __u8 padding1[3]; 151 __be64 ec; /* Warning: the current limit is 31-bit anyway! */ 152 __be32 vid_hdr_offset; 153 __be32 data_offset; 154 __u8 padding2[36]; 155 __be32 hdr_crc; 156 } __attribute__ ((packed)); 157 158 /** 159 * struct ubi_vid_hdr - on-flash UBI volume identifier header. 160 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC) 161 * @version: UBI implementation version which is supposed to accept this UBI 162 * image (%UBI_VERSION) 163 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC) 164 * @copy_flag: if this logical eraseblock was copied from another physical 165 * eraseblock (for wear-leveling reasons) 166 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE, 167 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT) 168 * @vol_id: ID of this volume 169 * @lnum: logical eraseblock number 170 * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be 171 * removed, kept only for not breaking older UBI users) 172 * @data_size: how many bytes of data this logical eraseblock contains 173 * @used_ebs: total number of used logical eraseblocks in this volume 174 * @data_pad: how many bytes at the end of this physical eraseblock are not 175 * used 176 * @data_crc: CRC checksum of the data stored in this logical eraseblock 177 * @padding1: reserved for future, zeroes 178 * @sqnum: sequence number 179 * @padding2: reserved for future, zeroes 180 * @hdr_crc: volume identifier header CRC checksum 181 * 182 * The @sqnum is the value of the global sequence counter at the time when this 183 * VID header was created. The global sequence counter is incremented each time 184 * UBI writes a new VID header to the flash, i.e. when it maps a logical 185 * eraseblock to a new physical eraseblock. The global sequence counter is an 186 * unsigned 64-bit integer and we assume it never overflows. The @sqnum 187 * (sequence number) is used to distinguish between older and newer versions of 188 * logical eraseblocks. 189 * 190 * There are 2 situations when there may be more then one physical eraseblock 191 * corresponding to the same logical eraseblock, i.e., having the same @vol_id 192 * and @lnum values in the volume identifier header. Suppose we have a logical 193 * eraseblock L and it is mapped to the physical eraseblock P. 194 * 195 * 1. Because UBI may erase physical eraseblocks asynchronously, the following 196 * situation is possible: L is asynchronously erased, so P is scheduled for 197 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1, 198 * so P1 is written to, then an unclean reboot happens. Result - there are 2 199 * physical eraseblocks P and P1 corresponding to the same logical eraseblock 200 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the 201 * flash. 202 * 203 * 2. From time to time UBI moves logical eraseblocks to other physical 204 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P 205 * to P1, and an unclean reboot happens before P is physically erased, there 206 * are two physical eraseblocks P and P1 corresponding to L and UBI has to 207 * select one of them when the flash is attached. The @sqnum field says which 208 * PEB is the original (obviously P will have lower @sqnum) and the copy. But 209 * it is not enough to select the physical eraseblock with the higher sequence 210 * number, because the unclean reboot could have happen in the middle of the 211 * copying process, so the data in P is corrupted. It is also not enough to 212 * just select the physical eraseblock with lower sequence number, because the 213 * data there may be old (consider a case if more data was added to P1 after 214 * the copying). Moreover, the unclean reboot may happen when the erasure of P 215 * was just started, so it result in unstable P, which is "mostly" OK, but 216 * still has unstable bits. 217 * 218 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a 219 * copy. UBI also calculates data CRC when the data is moved and stores it at 220 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical 221 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is 222 * examined. If it is cleared, the situation* is simple and the newer one is 223 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC 224 * checksum is correct, this physical eraseblock is selected (P1). Otherwise 225 * the older one (P) is selected. 226 * 227 * Note, there is an obsolete @leb_ver field which was used instead of @sqnum 228 * in the past. But it is not used anymore and we keep it in order to be able 229 * to deal with old UBI images. It will be removed at some point. 230 * 231 * There are 2 sorts of volumes in UBI: user volumes and internal volumes. 232 * Internal volumes are not seen from outside and are used for various internal 233 * UBI purposes. In this implementation there is only one internal volume - the 234 * layout volume. Internal volumes are the main mechanism of UBI extensions. 235 * For example, in future one may introduce a journal internal volume. Internal 236 * volumes have their own reserved range of IDs. 237 * 238 * The @compat field is only used for internal volumes and contains the "degree 239 * of their compatibility". It is always zero for user volumes. This field 240 * provides a mechanism to introduce UBI extensions and to be still compatible 241 * with older UBI binaries. For example, if someone introduced a journal in 242 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the 243 * journal volume. And in this case, older UBI binaries, which know nothing 244 * about the journal volume, would just delete this volume and work perfectly 245 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image 246 * - it just ignores the Ext3fs journal. 247 * 248 * The @data_crc field contains the CRC checksum of the contents of the logical 249 * eraseblock if this is a static volume. In case of dynamic volumes, it does 250 * not contain the CRC checksum as a rule. The only exception is when the 251 * data of the physical eraseblock was moved by the wear-leveling unit, then 252 * the wear-leveling unit calculates the data CRC and stores it in the 253 * @data_crc field. And of course, the @copy_flag is %in this case. 254 * 255 * The @data_size field is used only for static volumes because UBI has to know 256 * how many bytes of data are stored in this eraseblock. For dynamic volumes, 257 * this field usually contains zero. The only exception is when the data of the 258 * physical eraseblock was moved to another physical eraseblock for 259 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the 260 * contents and uses both @data_crc and @data_size fields. In this case, the 261 * @data_size field contains data size. 262 * 263 * The @used_ebs field is used only for static volumes and indicates how many 264 * eraseblocks the data of the volume takes. For dynamic volumes this field is 265 * not used and always contains zero. 266 * 267 * The @data_pad is calculated when volumes are created using the alignment 268 * parameter. So, effectively, the @data_pad field reduces the size of logical 269 * eraseblocks of this volume. This is very handy when one uses block-oriented 270 * software (say, cramfs) on top of the UBI volume. 271 */ 272 struct ubi_vid_hdr { 273 __be32 magic; 274 __u8 version; 275 __u8 vol_type; 276 __u8 copy_flag; 277 __u8 compat; 278 __be32 vol_id; 279 __be32 lnum; 280 __be32 leb_ver; /* obsolete, to be removed, don't use */ 281 __be32 data_size; 282 __be32 used_ebs; 283 __be32 data_pad; 284 __be32 data_crc; 285 __u8 padding1[4]; 286 __be64 sqnum; 287 __u8 padding2[12]; 288 __be32 hdr_crc; 289 } __attribute__ ((packed)); 290 291 /* Internal UBI volumes count */ 292 #define UBI_INT_VOL_COUNT 1 293 294 /* 295 * Starting ID of internal volumes. There is reserved room for 4096 internal 296 * volumes. 297 */ 298 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096) 299 300 /* The layout volume contains the volume table */ 301 302 #define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START 303 #define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC 304 #define UBI_LAYOUT_VOLUME_ALIGN 1 305 #define UBI_LAYOUT_VOLUME_EBS 2 306 #define UBI_LAYOUT_VOLUME_NAME "layout volume" 307 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT 308 309 /* The maximum number of volumes per one UBI device */ 310 #define UBI_MAX_VOLUMES 128 311 312 /* The maximum volume name length */ 313 #define UBI_VOL_NAME_MAX 127 314 315 /* Size of the volume table record */ 316 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record) 317 318 /* Size of the volume table record without the ending CRC */ 319 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32)) 320 321 /** 322 * struct ubi_vtbl_record - a record in the volume table. 323 * @reserved_pebs: how many physical eraseblocks are reserved for this volume 324 * @alignment: volume alignment 325 * @data_pad: how many bytes are unused at the end of the each physical 326 * eraseblock to satisfy the requested alignment 327 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME) 328 * @upd_marker: if volume update was started but not finished 329 * @name_len: volume name length 330 * @name: the volume name 331 * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG) 332 * @padding: reserved, zeroes 333 * @crc: a CRC32 checksum of the record 334 * 335 * The volume table records are stored in the volume table, which is stored in 336 * the layout volume. The layout volume consists of 2 logical eraseblock, each 337 * of which contains a copy of the volume table (i.e., the volume table is 338 * duplicated). The volume table is an array of &struct ubi_vtbl_record 339 * objects indexed by the volume ID. 340 * 341 * If the size of the logical eraseblock is large enough to fit 342 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES 343 * records. Otherwise, it contains as many records as it can fit (i.e., size of 344 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)). 345 * 346 * The @upd_marker flag is used to implement volume update. It is set to %1 347 * before update and set to %0 after the update. So if the update operation was 348 * interrupted, UBI knows that the volume is corrupted. 349 * 350 * The @alignment field is specified when the volume is created and cannot be 351 * later changed. It may be useful, for example, when a block-oriented file 352 * system works on top of UBI. The @data_pad field is calculated using the 353 * logical eraseblock size and @alignment. The alignment must be multiple to the 354 * minimal flash I/O unit. If @alignment is 1, all the available space of 355 * the physical eraseblocks is used. 356 * 357 * Empty records contain all zeroes and the CRC checksum of those zeroes. 358 */ 359 struct ubi_vtbl_record { 360 __be32 reserved_pebs; 361 __be32 alignment; 362 __be32 data_pad; 363 __u8 vol_type; 364 __u8 upd_marker; 365 __be16 name_len; 366 __u8 name[UBI_VOL_NAME_MAX+1]; 367 __u8 flags; 368 __u8 padding[23]; 369 __be32 crc; 370 } __attribute__ ((packed)); 371 372 #endif /* !__UBI_MEDIA_H__ */ 373