blob: fa479c71aa34bc6c0cf8738dcb2810b984b89294 [file] [log] [blame]
William Juulcfa460a2007-10-31 13:53:06 +01001/*
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 */
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__ */