summaryrefslogtreecommitdiff
path: root/include/mtd/ubi-header.h
blob: 12ce1c9e5b5210a97ed68b9e6b32e7904c3c1aa3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
/*
 * 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 B. Bityutskiy
 *          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.
 */

#ifndef __UBI_HEADER_H__
#define __UBI_HEADER_H__

#include <mtd_swab.h>

/* The version of this UBI implementation */
#define UBI_VERSION 1

/* The highest erase counter value supported by this implementation of UBI */
#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF

/* The initial CRC32 value used when calculating CRC checksums */
#define UBI_CRC32_INIT 0xFFFFFFFFU

/**
 * Magic numbers of the UBI headers.
 *
 * @UBI_EC_HDR_MAGIC: erase counter header magic number (ASCII "UBI#")
 * @UBI_VID_HDR_MAGIC: volume identifier header magic number (ASCII "UBI!")
 */
enum {
	UBI_EC_HDR_MAGIC  = 0x55424923,
	UBI_VID_HDR_MAGIC = 0x55424921
};

/**
 * Molume type constants used in volume identifier headers.
 *
 * @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_IGNORE: ignore this internal volume, but the UBI wear-leveling
 * unit may still move these logical eraseblocks to ensure wear-leveling
 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
 * physical eraseblocks, don't even 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_IGNORE   = 3,
	UBI_COMPAT_PRESERVE = 4,
	UBI_COMPAT_REJECT   = 5
};

/*
 * ubi16_t/ubi32_t/ubi64_t - 16, 32, and 64-bit integers used in UBI on-flash
 * data structures.
 */
typedef struct {
	uint16_t int16;
} __attribute__ ((packed)) ubi16_t;

typedef struct {
	uint32_t int32;
} __attribute__ ((packed)) ubi32_t;

typedef struct {
	uint64_t int64;
} __attribute__ ((packed)) ubi64_t;

/*
 * In this implementation UBI uses the big-endian format for on-flash integers.
 * The below are the corresponding endianess conversion macros.
 */
#define cpu_to_ubi16(x) ((ubi16_t){cpu_to_be16(x)})
#define ubi16_to_cpu(x) ((uint16_t)be16_to_cpu((x).int16))

#define cpu_to_ubi32(x) ((ubi32_t){cpu_to_be32(x)})
#define ubi32_to_cpu(x) ((uint32_t)be32_to_cpu((x).int32))

#define cpu_to_ubi64(x) ((ubi64_t){cpu_to_be64(x)})
#define ubi64_to_cpu(x) ((uint64_t)be64_to_cpu((x).int64))

/*
 * 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(ubi32_t))
#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(ubi32_t))

/*
 * How much private data may internal volumes store in the VID header.
 */
#define UBI_VID_HDR_IVOL_DATA_SIZE 12

/**
 * struct ubi_ec_hdr - UBI erase counter header.
 *
 * @magic: the erase counter header magic number (%UBI_EC_HDR_MAGIC)
 * @version: the version of UBI implementation which is supposed to accept this
 * UBI image (%UBI_VERSION)
 * @padding1: reserved for future, zeroes
 * @ec: the erase counter
 * @vid_hdr_offset: where the VID header begins
 * @data_offset: where the user data begins
 * @padding2: reserved for future, zeroes
 * @hdr_crc: the 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 rejecter. 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
 * eraseblock. These values have to be the same for all eraseblocks.
 */
struct ubi_ec_hdr {
	ubi32_t magic;
	uint8_t version;
	uint8_t padding1[3];
	ubi64_t ec; /* Warning: the current limit is 31-bit anyway! */
	ubi32_t vid_hdr_offset;
	ubi32_t data_offset;
	uint8_t padding2[36];
	ubi32_t 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: a flag indicating if this physical eraseblock was created by
 * means of copying an original physical eraseblock to ensure wear-leveling.
 * @compat: compatibility of this volume (%UBI_COMPAT_DELETE,
 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 * @leb_ver: eraseblock copy number
 * @data_size: how many bytes of data this eraseblock contains.
 * @used_ebs: total number of used logical eraseblocks in this volume
 * @data_pad: how many bytes at the end of this eraseblock are not used
 * @data_crc: CRC checksum of data containing in this eraseblock
 * @padding1: reserved for future, zeroes
 * @ivol_data: private data of internal volumes
 * @hdr_crc: volume identifier header CRC checksum
 *
 * The @leb_ver and the @copy_flag fields are used to distinguish between older
 * and newer copies of logical eraseblocks, as well as to guarantee robustness
 * to unclean reboots. As UBI erases logical eraseblocks asynchronously, it has
 * to distinguish between older and newer copies of eraseblocks. This is done
 * using the @version field. On the other hand, when UBI moves an eraseblock,
 * its version is also increased and the @copy_flag is set to 1. Additionally,
 * when moving eraseblocks, UBI calculates data CRC and stores it in the
 * @data_crc field, even for dynamic volumes.
 *
 * Thus, if there are 2 eraseblocks of the same volume and logical number, UBI
 * uses the following algorithm to pick one of them. It first picks the one
 * with larger version (say, A). If @copy_flag is not set, then A is picked. If
 * @copy_flag is set, UBI checks the CRC of the eraseblock (@data_crc). This is
 * needed to ensure that copying was finished. If the CRC is all right, A is
 * picked. If not, the older eraseblock is picked.
 *
 * Note, the @leb_ver field may overflow. Thus, if you have 2 versions A and B,
 * then A > B if abs(A-B) < 0x7FFFFFFF, and A < B otherwise.
 *
 * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
 * Internal volumes are not seen from outside and are used for different
 * internal UBI purposes. In this implementation there are only two internal
 * volumes: the layout volume and the update volume. Internal volumes are the
 * main mechanism of UBI extensions. For example, in future one may introduce a
 * journal internal volume.
 *
 * The @compat field is only used for internal volumes and contains the degree
 * of their compatibility. This field 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 an
 * journal internal volume in future, he would probably use %UBI_COMPAT_DELETE
 * compatibility.  And in this case, older UBI binaries, which know nothing
 * about the journal volume, would just delete this and work perfectly fine.
 * This is somewhat 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
 * logical eraseblock was moved by the wear-leveling unit, then the
 * wear-leveling unit calculates the eraseblocks' CRC and stores it at
 * @data_crc.
 *
 * The @data_size field is always used for static volumes because we want to
 * know about how many bytes of data are stored in this eraseblock.  For
 * dynamic eraseblocks, this field usually contains zero. The only exception is
 * when the logical eraseblock is moved to another physical eraseblock due to
 * 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 the size of logical eraseblock of this volume
 * (which may vary owing to @alignment).
 *
 * 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.
 *
 * The @ivol_data contains private data of internal volumes. This might be very
 * handy to store data in the VID header, not in the eraseblock's contents. For
 * example it may make life of simple boot-loaders easier. The @ivol_data field
 * contains zeroes for user volumes.
 */
struct ubi_vid_hdr {
	ubi32_t magic;
	uint8_t version;
	uint8_t vol_type;
	uint8_t copy_flag;
	uint8_t compat;
	ubi32_t vol_id;
	ubi32_t lnum;
	ubi32_t leb_ver;
	ubi32_t data_size;
	ubi32_t used_ebs;
	ubi32_t data_pad;
	ubi32_t data_crc;
	uint8_t padding1[12];
	uint8_t ivol_data[UBI_VID_HDR_IVOL_DATA_SIZE];
	ubi32_t hdr_crc;
} __attribute__ ((packed));

/**
 * struct ubi_vid_hdr_upd_vol - private data of the update internal volume
 * stored in volume identifier headers.
 *
 * @vol_id: volume ID of the volume under update
 * @padding: zeroes
 */
struct ubi_vid_hdr_upd_vol {
	ubi32_t vol_id;
	uint8_t padding[UBI_VID_HDR_IVOL_DATA_SIZE - 4];
} __attribute__ ((packed));

/*
 * Count of internal UBI volumes.
 */
#define UBI_INT_VOL_COUNT 2

/*
 * Internal volume IDs start from this digit. There is a reserved room for 4096
 * internal volumes.
 */
#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)

/**
 * enum ubi_internal_volume_numbers - volume IDs of internal UBI volumes.
 *
 * %UBI_LAYOUT_VOL_ID: volume ID of the layout volume
 * %UBI_UPDATE_VOL_ID: volume ID of the update volume
 */
enum ubi_internal_volume_ids {
	UBI_LAYOUT_VOL_ID = UBI_INTERNAL_VOL_START,
	UBI_UPDATE_VOL_ID = UBI_INTERNAL_VOL_START + 1
};

/*
 * Number of logical eraseblocks reserved for internal volumes.
 */
#define UBI_LAYOUT_VOLUME_EBS 2
#define UBI_UPDATE_VOLUME_EBS 1

/*
 * Names of internal volumes
 */
#define UBI_LAYOUT_VOLUME_NAME "The layout volume"
#define UBI_UPDATE_VOLUME_NAME "The update volume"

/*
 * Compatibility flags of internal volumes.
 */
#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
#define UBI_UPDATE_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 volume table records.
 */
#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vol_tbl_record)

/*
 * Size of volume table records without the ending CRC.
 */
#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(ubi32_t))

/**
 * struct ubi_vol_tbl_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 not used at the end of the eraseblocks to
 * satisfy the requested alignment
 * @padding1: reserved, zeroes
 * @name_len: the volume name length
 * @name: the volume name
 * @padding2: reserved, zeroes
 * @crc: a CRC32 checksum of the record
 *
 * The layout volume consists of 2 logical eraseblock, each of which contains
 * the volume table (i.e., the volume table is duplicated). The volume table is
 * an array of &struct ubi_vol_tbl_record objects indexed by the volume ID.
 *
 * If the size of the logical eraseblock is large enough to fit
 * %UBI_MAX_VOLUMES, the volume table contains %UBI_MAX_VOLUMES records.
 * Otherwise, it contains as much records as can be fit (i.e., size of logical
 * eraseblock divided by sizeof(struct ubi_vol_tbl_record)).
 *
 * 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
 * eraseblocks is used.
 *
 * Empty records contain all zeroes and the CRC checksum of those zeroes.
 */
struct ubi_vol_tbl_record {
	ubi32_t reserved_pebs;
	ubi32_t alignment;
	ubi32_t data_pad;
	uint8_t vol_type;
	uint8_t padding1;
	ubi16_t name_len;
	uint8_t name[UBI_VOL_NAME_MAX + 1];
	uint8_t padding2[24];
	ubi32_t crc;
} __attribute__ ((packed));

#endif /* !__UBI_HEADER_H__ */