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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 */
55enum {
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 */
93enum {
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 */
107enum {
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 */
147struct 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 */
272struct 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 */
359struct 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_HEADER_H__ */