Add basic support for mini2440 board to barebox.
[barebox-mini2440.git] / include / ubi-media.h
blob10490fdb1657ea47cc993bda32e1b185dd187911
1 /*
2 * Copyright (c) International Business Machines Corp., 2006
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.
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.
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
18 * Authors: Artem Bityutskiy (Битюцкий Артём)
19 * Thomas Gleixner
20 * Frank Haverkamp
21 * Oliver Lohmann
22 * Andreas Arnez
26 * This file defines the layout of UBI headers and all the other UBI on-flash
27 * data structures.
30 #ifndef __UBI_MEDIA_H__
31 #define __UBI_MEDIA_H__
33 #ifndef DOXYGEN_SHOULD_SKIP_THIS
35 #include <asm/byteorder.h>
37 /* The version of UBI images supported by this implementation */
38 #define UBI_VERSION 1
40 /* The highest erase counter value supported by this implementation */
41 #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
43 /* The initial CRC32 value used when calculating CRC checksums */
44 #define UBI_CRC32_INIT 0xFFFFFFFFU
46 /* Erase counter header magic number (ASCII "UBI#") */
47 #define UBI_EC_HDR_MAGIC 0x55424923
48 /* Volume identifier header magic number (ASCII "UBI!") */
49 #define UBI_VID_HDR_MAGIC 0x55424921
52 * Volume type constants used in the volume identifier header.
54 * @UBI_VID_DYNAMIC: dynamic volume
55 * @UBI_VID_STATIC: static volume
57 enum {
58 UBI_VID_DYNAMIC = 1,
59 UBI_VID_STATIC = 2
63 * Volume flags used in the volume table record.
65 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
67 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
68 * table. UBI automatically re-sizes the volume which has this flag and makes
69 * the volume to be of largest possible size. This means that if after the
70 * initialization UBI finds out that there are available physical eraseblocks
71 * present on the device, it automatically appends all of them to the volume
72 * (the physical eraseblocks reserved for bad eraseblocks handling and other
73 * reserved physical eraseblocks are not taken). So, if there is a volume with
74 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
75 * eraseblocks will be zero after UBI is loaded, because all of them will be
76 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
77 * after the volume had been initialized.
79 * The auto-resize feature is useful for device production purposes. For
80 * example, different NAND flash chips may have different amount of initial bad
81 * eraseblocks, depending of particular chip instance. Manufacturers of NAND
82 * chips usually guarantee that the amount of initial bad eraseblocks does not
83 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
84 * flashed to the end devices in production, he does not know the exact amount
85 * of good physical eraseblocks the NAND chip on the device will have, but this
86 * number is required to calculate the volume sized and put them to the volume
87 * table of the UBI image. In this case, one of the volumes (e.g., the one
88 * which will store the root file system) is marked as "auto-resizable", and
89 * UBI will adjust its size on the first boot if needed.
91 * Note, first UBI reserves some amount of physical eraseblocks for bad
92 * eraseblock handling, and then re-sizes the volume, not vice-versa. This
93 * means that the pool of reserved physical eraseblocks will always be present.
95 enum {
96 UBI_VTBL_AUTORESIZE_FLG = 0x01,
100 * Compatibility constants used by internal volumes.
102 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
103 * to the flash
104 * @UBI_COMPAT_RO: attach this device in read-only mode
105 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
106 * physical eraseblocks, don't allow the wear-leveling
107 * sub-system to move them
108 * @UBI_COMPAT_REJECT: reject this UBI image
110 enum {
111 UBI_COMPAT_DELETE = 1,
112 UBI_COMPAT_RO = 2,
113 UBI_COMPAT_PRESERVE = 4,
114 UBI_COMPAT_REJECT = 5
117 /* Sizes of UBI headers */
118 #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr)
119 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
121 /* Sizes of UBI headers without the ending CRC */
122 #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32))
123 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
126 * struct ubi_ec_hdr - UBI erase counter header.
127 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
128 * @version: version of UBI implementation which is supposed to accept this
129 * UBI image
130 * @padding1: reserved for future, zeroes
131 * @ec: the erase counter
132 * @vid_hdr_offset: where the VID header starts
133 * @data_offset: where the user data start
134 * @padding2: reserved for future, zeroes
135 * @hdr_crc: erase counter header CRC checksum
137 * The erase counter header takes 64 bytes and has a plenty of unused space for
138 * future usage. The unused fields are zeroed. The @version field is used to
139 * indicate the version of UBI implementation which is supposed to be able to
140 * work with this UBI image. If @version is greater than the current UBI
141 * version, the image is rejected. This may be useful in future if something
142 * is changed radically. This field is duplicated in the volume identifier
143 * header.
145 * The @vid_hdr_offset and @data_offset fields contain the offset of the the
146 * volume identifier header and user data, relative to the beginning of the
147 * physical eraseblock. These values have to be the same for all physical
148 * eraseblocks.
150 struct ubi_ec_hdr {
151 __be32 magic;
152 __u8 version;
153 __u8 padding1[3];
154 __be64 ec; /* Warning: the current limit is 31-bit anyway! */
155 __be32 vid_hdr_offset;
156 __be32 data_offset;
157 __u8 padding2[36];
158 __be32 hdr_crc;
159 } __attribute__ ((packed));
162 * struct ubi_vid_hdr - on-flash UBI volume identifier header.
163 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
164 * @version: UBI implementation version which is supposed to accept this UBI
165 * image (%UBI_VERSION)
166 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
167 * @copy_flag: if this logical eraseblock was copied from another physical
168 * eraseblock (for wear-leveling reasons)
169 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
170 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
171 * @vol_id: ID of this volume
172 * @lnum: logical eraseblock number
173 * @padding1: reserved for future, zeroes
174 * @data_size: how many bytes of data this logical eraseblock contains
175 * @used_ebs: total number of used logical eraseblocks in this volume
176 * @data_pad: how many bytes at the end of this physical eraseblock are not
177 * used
178 * @data_crc: CRC checksum of the data stored in this logical eraseblock
179 * @padding2: reserved for future, zeroes
180 * @sqnum: sequence number
181 * @padding3: reserved for future, zeroes
182 * @hdr_crc: volume identifier header CRC checksum
184 * The @sqnum is the value of the global sequence counter at the time when this
185 * VID header was created. The global sequence counter is incremented each time
186 * UBI writes a new VID header to the flash, i.e. when it maps a logical
187 * eraseblock to a new physical eraseblock. The global sequence counter is an
188 * unsigned 64-bit integer and we assume it never overflows. The @sqnum
189 * (sequence number) is used to distinguish between older and newer versions of
190 * logical eraseblocks.
192 * There are 2 situations when there may be more than one physical eraseblock
193 * corresponding to the same logical eraseblock, i.e., having the same @vol_id
194 * and @lnum values in the volume identifier header. Suppose we have a logical
195 * eraseblock L and it is mapped to the physical eraseblock P.
197 * 1. Because UBI may erase physical eraseblocks asynchronously, the following
198 * situation is possible: L is asynchronously erased, so P is scheduled for
199 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
200 * so P1 is written to, then an unclean reboot happens. Result - there are 2
201 * physical eraseblocks P and P1 corresponding to the same logical eraseblock
202 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
203 * flash.
205 * 2. From time to time UBI moves logical eraseblocks to other physical
206 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
207 * to P1, and an unclean reboot happens before P is physically erased, there
208 * are two physical eraseblocks P and P1 corresponding to L and UBI has to
209 * select one of them when the flash is attached. The @sqnum field says which
210 * PEB is the original (obviously P will have lower @sqnum) and the copy. But
211 * it is not enough to select the physical eraseblock with the higher sequence
212 * number, because the unclean reboot could have happen in the middle of the
213 * copying process, so the data in P is corrupted. It is also not enough to
214 * just select the physical eraseblock with lower sequence number, because the
215 * data there may be old (consider a case if more data was added to P1 after
216 * the copying). Moreover, the unclean reboot may happen when the erasure of P
217 * was just started, so it result in unstable P, which is "mostly" OK, but
218 * still has unstable bits.
220 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
221 * copy. UBI also calculates data CRC when the data is moved and stores it at
222 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
223 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
224 * examined. If it is cleared, the situation* is simple and the newer one is
225 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
226 * checksum is correct, this physical eraseblock is selected (P1). Otherwise
227 * the older one (P) is selected.
229 * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
230 * Internal volumes are not seen from outside and are used for various internal
231 * UBI purposes. In this implementation there is only one internal volume - the
232 * layout volume. Internal volumes are the main mechanism of UBI extensions.
233 * For example, in future one may introduce a journal internal volume. Internal
234 * volumes have their own reserved range of IDs.
236 * The @compat field is only used for internal volumes and contains the "degree
237 * of their compatibility". It is always zero for user volumes. This field
238 * provides a mechanism to introduce UBI extensions and to be still compatible
239 * with older UBI binaries. For example, if someone introduced a journal in
240 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
241 * journal volume. And in this case, older UBI binaries, which know nothing
242 * about the journal volume, would just delete this volume and work perfectly
243 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
244 * - it just ignores the Ext3fs journal.
246 * The @data_crc field contains the CRC checksum of the contents of the logical
247 * eraseblock if this is a static volume. In case of dynamic volumes, it does
248 * not contain the CRC checksum as a rule. The only exception is when the
249 * data of the physical eraseblock was moved by the wear-leveling sub-system,
250 * then the wear-leveling sub-system calculates the data CRC and stores it in
251 * the @data_crc field. And of course, the @copy_flag is %in this case.
253 * The @data_size field is used only for static volumes because UBI has to know
254 * how many bytes of data are stored in this eraseblock. For dynamic volumes,
255 * this field usually contains zero. The only exception is when the data of the
256 * physical eraseblock was moved to another physical eraseblock for
257 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
258 * contents and uses both @data_crc and @data_size fields. In this case, the
259 * @data_size field contains data size.
261 * The @used_ebs field is used only for static volumes and indicates how many
262 * eraseblocks the data of the volume takes. For dynamic volumes this field is
263 * not used and always contains zero.
265 * The @data_pad is calculated when volumes are created using the alignment
266 * parameter. So, effectively, the @data_pad field reduces the size of logical
267 * eraseblocks of this volume. This is very handy when one uses block-oriented
268 * software (say, cramfs) on top of the UBI volume.
270 struct ubi_vid_hdr {
271 __be32 magic;
272 __u8 version;
273 __u8 vol_type;
274 __u8 copy_flag;
275 __u8 compat;
276 __be32 vol_id;
277 __be32 lnum;
278 __be32 leb_ver;
279 __be32 data_size;
280 __be32 used_ebs;
281 __be32 data_pad;
282 __be32 data_crc;
283 __u8 padding2[4];
284 __be64 sqnum;
285 __u8 padding3[12];
286 __be32 hdr_crc;
287 } __attribute__ ((packed));
289 /* Internal UBI volumes count */
290 #define UBI_INT_VOL_COUNT 1
293 * Starting ID of internal volumes. There is reserved room for 4096 internal
294 * volumes.
296 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
298 /* The layout volume contains the volume table */
300 #define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START
301 #define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC
302 #define UBI_LAYOUT_VOLUME_ALIGN 1
303 #define UBI_LAYOUT_VOLUME_EBS 2
304 #define UBI_LAYOUT_VOLUME_NAME "layout volume"
305 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
307 /* The maximum number of volumes per one UBI device */
308 #define UBI_MAX_VOLUMES 128
310 /* The maximum volume name length */
311 #define UBI_VOL_NAME_MAX 127
313 /* Size of the volume table record */
314 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
316 /* Size of the volume table record without the ending CRC */
317 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
320 * struct ubi_vtbl_record - a record in the volume table.
321 * @reserved_pebs: how many physical eraseblocks are reserved for this volume
322 * @alignment: volume alignment
323 * @data_pad: how many bytes are unused at the end of the each physical
324 * eraseblock to satisfy the requested alignment
325 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
326 * @upd_marker: if volume update was started but not finished
327 * @name_len: volume name length
328 * @name: the volume name
329 * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
330 * @padding: reserved, zeroes
331 * @crc: a CRC32 checksum of the record
333 * The volume table records are stored in the volume table, which is stored in
334 * the layout volume. The layout volume consists of 2 logical eraseblock, each
335 * of which contains a copy of the volume table (i.e., the volume table is
336 * duplicated). The volume table is an array of &struct ubi_vtbl_record
337 * objects indexed by the volume ID.
339 * If the size of the logical eraseblock is large enough to fit
340 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
341 * records. Otherwise, it contains as many records as it can fit (i.e., size of
342 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
344 * The @upd_marker flag is used to implement volume update. It is set to %1
345 * before update and set to %0 after the update. So if the update operation was
346 * interrupted, UBI knows that the volume is corrupted.
348 * The @alignment field is specified when the volume is created and cannot be
349 * later changed. It may be useful, for example, when a block-oriented file
350 * system works on top of UBI. The @data_pad field is calculated using the
351 * logical eraseblock size and @alignment. The alignment must be multiple to the
352 * minimal flash I/O unit. If @alignment is 1, all the available space of
353 * the physical eraseblocks is used.
355 * Empty records contain all zeroes and the CRC checksum of those zeroes.
357 struct ubi_vtbl_record {
358 __be32 reserved_pebs;
359 __be32 alignment;
360 __be32 data_pad;
361 __u8 vol_type;
362 __u8 upd_marker;
363 __be16 name_len;
364 __u8 name[UBI_VOL_NAME_MAX+1];
365 __u8 flags;
366 __u8 padding[23];
367 __be32 crc;
368 } __attribute__ ((packed));
370 #endif /* DOXYGEN_SHOULD_SKIP_THIS */
372 #endif /* !__UBI_MEDIA_H__ */