include/mtd/ubi-user.h

   1 /*
   2  * Copyright © International Business Machines Corp., 2006
   3  *
   4  * SPDX-License-Identifier:    GPL-2.0+
   5  *
   6  * Author: Artem Bityutskiy (Битюцкий Артём)
   7  */
   8
   9 #ifndef __UBI_USER_H__
  10 #define __UBI_USER_H__
  11
  12 #include <linux/types.h>
  13
  14 /*
  15  * UBI device creation (the same as MTD device attachment)
  16  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  17  *
  18  * MTD devices may be attached using %UBI_IOCATT ioctl command of the UBI
  19  * control device. The caller has to properly fill and pass
  20  * &struct ubi_attach_req object - UBI will attach the MTD device specified in
  21  * the request and return the newly created UBI device number as the ioctl
  22  * return value.
  23  *
  24  * UBI device deletion (the same as MTD device detachment)
  25  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  26  *
  27  * An UBI device maybe deleted with %UBI_IOCDET ioctl command of the UBI
  28  * control device.
  29  *
  30  * UBI volume creation
  31  * ~~~~~~~~~~~~~~~~~~~
  32  *
  33  * UBI volumes are created via the %UBI_IOCMKVOL ioctl command of UBI character
  34  * device. A &struct ubi_mkvol_req object has to be properly filled and a
  35  * pointer to it has to be passed to the ioctl.
  36  *
  37  * UBI volume deletion
  38  * ~~~~~~~~~~~~~~~~~~~
  39  *
  40  * To delete a volume, the %UBI_IOCRMVOL ioctl command of the UBI character
  41  * device should be used. A pointer to the 32-bit volume ID hast to be passed
  42  * to the ioctl.
  43  *
  44  * UBI volume re-size
  45  * ~~~~~~~~~~~~~~~~~~
  46  *
  47  * To re-size a volume, the %UBI_IOCRSVOL ioctl command of the UBI character
  48  * device should be used. A &struct ubi_rsvol_req object has to be properly
  49  * filled and a pointer to it has to be passed to the ioctl.
  50  *
  51  * UBI volumes re-name
  52  * ~~~~~~~~~~~~~~~~~~~
  53  *
  54  * To re-name several volumes atomically at one go, the %UBI_IOCRNVOL command
  55  * of the UBI character device should be used. A &struct ubi_rnvol_req object
  56  * has to be properly filled and a pointer to it has to be passed to the ioctl.
  57  *
  58  * UBI volume update
  59  * ~~~~~~~~~~~~~~~~~
  60  *
  61  * Volume update should be done via the %UBI_IOCVOLUP ioctl command of the
  62  * corresponding UBI volume character device. A pointer to a 64-bit update
  63  * size should be passed to the ioctl. After this, UBI expects user to write
  64  * this number of bytes to the volume character device. The update is finished
  65  * when the claimed number of bytes is passed. So, the volume update sequence
  66  * is something like:
  67  *
  68  * fd = open("/dev/my_volume");
  69  * ioctl(fd, UBI_IOCVOLUP, &image_size);
  70  * write(fd, buf, image_size);
  71  * close(fd);
  72  *
  73  * Logical eraseblock erase
  74  * ~~~~~~~~~~~~~~~~~~~~~~~~
  75  *
  76  * To erase a logical eraseblock, the %UBI_IOCEBER ioctl command of the
  77  * corresponding UBI volume character device should be used. This command
  78  * unmaps the requested logical eraseblock, makes sure the corresponding
  79  * physical eraseblock is successfully erased, and returns.
  80  *
  81  * Atomic logical eraseblock change
  82  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  83  *
  84  * Atomic logical eraseblock change operation is called using the %UBI_IOCEBCH
  85  * ioctl command of the corresponding UBI volume character device. A pointer to
  86  * a &struct ubi_leb_change_req object has to be passed to the ioctl. Then the
  87  * user is expected to write the requested amount of bytes (similarly to what
  88  * should be done in case of the "volume update" ioctl).
  89  *
  90  * Logical eraseblock map
  91  * ~~~~~~~~~~~~~~~~~~~~~
  92  *
  93  * To map a logical eraseblock to a physical eraseblock, the %UBI_IOCEBMAP
  94  * ioctl command should be used. A pointer to a &struct ubi_map_req object is
  95  * expected to be passed. The ioctl maps the requested logical eraseblock to
  96  * a physical eraseblock and returns.  Only non-mapped logical eraseblocks can
  97  * be mapped. If the logical eraseblock specified in the request is already
  98  * mapped to a physical eraseblock, the ioctl fails and returns error.
  99  *
 100  * Logical eraseblock unmap
 101  * ~~~~~~~~~~~~~~~~~~~~~~~~
 102  *
 103  * To unmap a logical eraseblock to a physical eraseblock, the %UBI_IOCEBUNMAP
 104  * ioctl command should be used. The ioctl unmaps the logical eraseblocks,
 105  * schedules corresponding physical eraseblock for erasure, and returns. Unlike
 106  * the "LEB erase" command, it does not wait for the physical eraseblock being
 107  * erased. Note, the side effect of this is that if an unclean reboot happens
 108  * after the unmap ioctl returns, you may find the LEB mapped again to the same
 109  * physical eraseblock after the UBI is run again.
 110  *
 111  * Check if logical eraseblock is mapped
 112  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 113  *
 114  * To check if a logical eraseblock is mapped to a physical eraseblock, the
 115  * %UBI_IOCEBISMAP ioctl command should be used. It returns %0 if the LEB is
 116  * not mapped, and %1 if it is mapped.
 117  *
 118  * Set an UBI volume property
 119  * ~~~~~~~~~~~~~~~~~~~~~~~~~
 120  *
 121  * To set an UBI volume property the %UBI_IOCSETPROP ioctl command should be
 122  * used. A pointer to a &struct ubi_set_vol_prop_req object is expected to be
 123  * passed. The object describes which property should be set, and to which value
 124  * it should be set.
 125  *
 126  * Block devices on UBI volumes
 127  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 128  *
 129  * To create a R/O block device on top of an UBI volume the %UBI_IOCVOLCRBLK
 130  * should be used. A pointer to a &struct ubi_blkcreate_req object is expected
 131  * to be passed, which is not used and reserved for future usage.
 132  *
 133  * Conversely, to remove a block device the %UBI_IOCVOLRMBLK should be used,
 134  * which takes no arguments.
 135  */
 136
 137 /*
 138  * When a new UBI volume or UBI device is created, users may either specify the
 139  * volume/device number they want to create or to let UBI automatically assign
 140  * the number using these constants.
 141  */
 142 #define UBI_VOL_NUM_AUTO (-1)
 143 #define UBI_DEV_NUM_AUTO (-1)
 144
 145 /* Maximum volume name length */
 146 #define UBI_MAX_VOLUME_NAME 127
 147
 148 /* ioctl commands of UBI character devices */
 149
 150 #define UBI_IOC_MAGIC 'o'
 151
 152 /* Create an UBI volume */
 153 #define UBI_IOCMKVOL _IOW(UBI_IOC_MAGIC, 0, struct ubi_mkvol_req)
 154 /* Remove an UBI volume */
 155 #define UBI_IOCRMVOL _IOW(UBI_IOC_MAGIC, 1, __s32)
 156 /* Re-size an UBI volume */
 157 #define UBI_IOCRSVOL _IOW(UBI_IOC_MAGIC, 2, struct ubi_rsvol_req)
 158 /* Re-name volumes */
 159 #define UBI_IOCRNVOL _IOW(UBI_IOC_MAGIC, 3, struct ubi_rnvol_req)
 160
 161 /* ioctl commands of the UBI control character device */
 162
 163 #define UBI_CTRL_IOC_MAGIC 'o'
 164
 165 /* Attach an MTD device */
 166 #define UBI_IOCATT _IOW(UBI_CTRL_IOC_MAGIC, 64, struct ubi_attach_req)
 167 /* Detach an MTD device */
 168 #define UBI_IOCDET _IOW(UBI_CTRL_IOC_MAGIC, 65, __s32)
 169
 170 /* ioctl commands of UBI volume character devices */
 171
 172 #define UBI_VOL_IOC_MAGIC 'O'
 173
 174 /* Start UBI volume update
 175  * Note: This actually takes a pointer (__s64*), but we can't change
 176  *       that without breaking the ABI on 32bit systems
 177  */
 178 #define UBI_IOCVOLUP _IOW(UBI_VOL_IOC_MAGIC, 0, __s64)
 179 /* LEB erasure command, used for debugging, disabled by default */
 180 #define UBI_IOCEBER _IOW(UBI_VOL_IOC_MAGIC, 1, __s32)
 181 /* Atomic LEB change command */
 182 #define UBI_IOCEBCH _IOW(UBI_VOL_IOC_MAGIC, 2, __s32)
 183 /* Map LEB command */
 184 #define UBI_IOCEBMAP _IOW(UBI_VOL_IOC_MAGIC, 3, struct ubi_map_req)
 185 /* Unmap LEB command */
 186 #define UBI_IOCEBUNMAP _IOW(UBI_VOL_IOC_MAGIC, 4, __s32)
 187 /* Check if LEB is mapped command */
 188 #define UBI_IOCEBISMAP _IOR(UBI_VOL_IOC_MAGIC, 5, __s32)
 189 /* Set an UBI volume property */
 190 #define UBI_IOCSETVOLPROP _IOW(UBI_VOL_IOC_MAGIC, 6, \
 191                                struct ubi_set_vol_prop_req)
 192 /* Create a R/O block device on top of an UBI volume */
 193 #define UBI_IOCVOLCRBLK _IOW(UBI_VOL_IOC_MAGIC, 7, struct ubi_blkcreate_req)
 194 /* Remove the R/O block device */
 195 #define UBI_IOCVOLRMBLK _IO(UBI_VOL_IOC_MAGIC, 8)
 196
 197 /* Maximum MTD device name length supported by UBI */
 198 #define MAX_UBI_MTD_NAME_LEN 127
 199
 200 /* Maximum amount of UBI volumes that can be re-named at one go */
 201 #define UBI_MAX_RNVOL 32
 202
 203 /*
 204  * UBI volume type constants.
 205  *
 206  * @UBI_DYNAMIC_VOLUME: dynamic volume
 207  * @UBI_STATIC_VOLUME:  static volume
 208  */
 209 enum {
 210         UBI_DYNAMIC_VOLUME = 3,
 211         UBI_STATIC_VOLUME  = 4,
 212 };
 213
 214 /*
 215  * UBI set volume property ioctl constants.
 216  *
 217  * @UBI_VOL_PROP_DIRECT_WRITE: allow (any non-zero value) or disallow (value 0)
 218  *                             user to directly write and erase individual
 219  *                             eraseblocks on dynamic volumes
 220  */
 221 enum {
 222         UBI_VOL_PROP_DIRECT_WRITE = 1,
 223 };
 224
 225 /**
 226  * struct ubi_attach_req - attach MTD device request.
 227  * @ubi_num: UBI device number to create
 228  * @mtd_num: MTD device number to attach
 229  * @vid_hdr_offset: VID header offset (use defaults if %0)
 230  * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
 231  * @padding: reserved for future, not used, has to be zeroed
 232  *
 233  * This data structure is used to specify MTD device UBI has to attach and the
 234  * parameters it has to use. The number which should be assigned to the new UBI
 235  * device is passed in @ubi_num. UBI may automatically assign the number if
 236  * @UBI_DEV_NUM_AUTO is passed. In this case, the device number is returned in
 237  * @ubi_num.
 238  *
 239  * Most applications should pass %0 in @vid_hdr_offset to make UBI use default
 240  * offset of the VID header within physical eraseblocks. The default offset is
 241  * the next min. I/O unit after the EC header. For example, it will be offset
 242  * 512 in case of a 512 bytes page NAND flash with no sub-page support. Or
 243  * it will be 512 in case of a 2KiB page NAND flash with 4 512-byte sub-pages.
 244  *
 245  * But in rare cases, if this optimizes things, the VID header may be placed to
 246  * a different offset. For example, the boot-loader might do things faster if
 247  * the VID header sits at the end of the first 2KiB NAND page with 4 sub-pages.
 248  * As the boot-loader would not normally need to read EC headers (unless it
 249  * needs UBI in RW mode), it might be faster to calculate ECC. This is weird
 250  * example, but it real-life example. So, in this example, @vid_hdr_offer would
 251  * be 2KiB-64 bytes = 1984. Note, that this position is not even 512-bytes
 252  * aligned, which is OK, as UBI is clever enough to realize this is 4th
 253  * sub-page of the first page and add needed padding.
 254  *
 255  * The @max_beb_per1024 is the maximum amount of bad PEBs UBI expects on the
 256  * UBI device per 1024 eraseblocks.  This value is often given in an other form
 257  * in the NAND datasheet (min NVB i.e. minimal number of valid blocks). The
 258  * maximum expected bad eraseblocks per 1024 is then:
 259  *    1024 * (1 - MinNVB / MaxNVB)
 260  * Which gives 20 for most NAND devices.  This limit is used in order to derive
 261  * amount of eraseblock UBI reserves for handling new bad blocks. If the device
 262  * has more bad eraseblocks than this limit, UBI does not reserve any physical
 263  * eraseblocks for new bad eraseblocks, but attempts to use available
 264  * eraseblocks (if any). The accepted range is 0-768. If 0 is given, the
 265  * default kernel value of %CONFIG_MTD_UBI_BEB_LIMIT will be used.
 266  */
 267 struct ubi_attach_req {
 268         __s32 ubi_num;
 269         __s32 mtd_num;
 270         __s32 vid_hdr_offset;
 271         __s16 max_beb_per1024;
 272         __s8 padding[10];
 273 };
 274
 275 /**
 276  * struct ubi_mkvol_req - volume description data structure used in
 277  *                        volume creation requests.
 278  * @vol_id: volume number
 279  * @alignment: volume alignment
 280  * @bytes: volume size in bytes
 281  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
 282  * @padding1: reserved for future, not used, has to be zeroed
 283  * @name_len: volume name length
 284  * @padding2: reserved for future, not used, has to be zeroed
 285  * @name: volume name
 286  *
 287  * This structure is used by user-space programs when creating new volumes. The
 288  * @used_bytes field is only necessary when creating static volumes.
 289  *
 290  * The @alignment field specifies the required alignment of the volume logical
 291  * eraseblock. This means, that the size of logical eraseblocks will be aligned
 292  * to this number, i.e.,
 293  *      (UBI device logical eraseblock size) mod (@alignment) = 0.
 294  *
 295  * To put it differently, the logical eraseblock of this volume may be slightly
 296  * shortened in order to make it properly aligned. The alignment has to be
 297  * multiple of the flash minimal input/output unit, or %1 to utilize the entire
 298  * available space of logical eraseblocks.
 299  *
 300  * The @alignment field may be useful, for example, when one wants to maintain
 301  * a block device on top of an UBI volume. In this case, it is desirable to fit
 302  * an integer number of blocks in logical eraseblocks of this UBI volume. With
 303  * alignment it is possible to update this volume using plane UBI volume image
 304  * BLOBs, without caring about how to properly align them.
 305  */
 306 struct ubi_mkvol_req {
 307         __s32 vol_id;
 308         __s32 alignment;
 309         __s64 bytes;
 310         __s8 vol_type;
 311         __s8 padding1;
 312         __s16 name_len;
 313         __s8 padding2[4];
 314         char name[UBI_MAX_VOLUME_NAME + 1];
 315 } __packed;
 316
 317 /**
 318  * struct ubi_rsvol_req - a data structure used in volume re-size requests.
 319  * @vol_id: ID of the volume to re-size
 320  * @bytes: new size of the volume in bytes
 321  *
 322  * Re-sizing is possible for both dynamic and static volumes. But while dynamic
 323  * volumes may be re-sized arbitrarily, static volumes cannot be made to be
 324  * smaller than the number of bytes they bear. To arbitrarily shrink a static
 325  * volume, it must be wiped out first (by means of volume update operation with
 326  * zero number of bytes).
 327  */
 328 struct ubi_rsvol_req {
 329         __s64 bytes;
 330         __s32 vol_id;
 331 } __packed;
 332
 333 /**
 334  * struct ubi_rnvol_req - volumes re-name request.
 335  * @count: count of volumes to re-name
 336  * @padding1:  reserved for future, not used, has to be zeroed
 337  * @vol_id: ID of the volume to re-name
 338  * @name_len: name length
 339  * @padding2:  reserved for future, not used, has to be zeroed
 340  * @name: new volume name
 341  *
 342  * UBI allows to re-name up to %32 volumes at one go. The count of volumes to
 343  * re-name is specified in the @count field. The ID of the volumes to re-name
 344  * and the new names are specified in the @vol_id and @name fields.
 345  *
 346  * The UBI volume re-name operation is atomic, which means that should power cut
 347  * happen, the volumes will have either old name or new name. So the possible
 348  * use-cases of this command is atomic upgrade. Indeed, to upgrade, say, volumes
 349  * A and B one may create temporary volumes %A1 and %B1 with the new contents,
 350  * then atomically re-name A1->A and B1->B, in which case old %A and %B will
 351  * be removed.
 352  *
 353  * If it is not desirable to remove old A and B, the re-name request has to
 354  * contain 4 entries: A1->A, A->A1, B1->B, B->B1, in which case old A1 and B1
 355  * become A and B, and old A and B will become A1 and B1.
 356  *
 357  * It is also OK to request: A1->A, A1->X, B1->B, B->Y, in which case old A1
 358  * and B1 become A and B, and old A and B become X and Y.
 359  *
 360  * In other words, in case of re-naming into an existing volume name, the
 361  * existing volume is removed, unless it is re-named as well at the same
 362  * re-name request.
 363  */
 364 struct ubi_rnvol_req {
 365         __s32 count;
 366         __s8 padding1[12];
 367         struct {
 368                 __s32 vol_id;
 369                 __s16 name_len;
 370                 __s8  padding2[2];
 371                 char    name[UBI_MAX_VOLUME_NAME + 1];
 372         } ents[UBI_MAX_RNVOL];
 373 } __packed;
 374
 375 /**
 376  * struct ubi_leb_change_req - a data structure used in atomic LEB change
 377  *                             requests.
 378  * @lnum: logical eraseblock number to change
 379  * @bytes: how many bytes will be written to the logical eraseblock
 380  * @dtype: pass "3" for better compatibility with old kernels
 381  * @padding: reserved for future, not used, has to be zeroed
 382  *
 383  * The @dtype field used to inform UBI about what kind of data will be written
 384  * to the LEB: long term (value 1), short term (value 2), unknown (value 3).
 385  * UBI tried to pick a PEB with lower erase counter for short term data and a
 386  * PEB with higher erase counter for long term data. But this was not really
 387  * used because users usually do not know this and could easily mislead UBI. We
 388  * removed this feature in May 2012. UBI currently just ignores the @dtype
 389  * field. But for better compatibility with older kernels it is recommended to
 390  * set @dtype to 3 (unknown).
 391  */
 392 struct ubi_leb_change_req {
 393         __s32 lnum;
 394         __s32 bytes;
 395         __s8  dtype; /* obsolete, do not use! */
 396         __s8  padding[7];
 397 } __packed;
 398
 399 /**
 400  * struct ubi_map_req - a data structure used in map LEB requests.
 401  * @dtype: pass "3" for better compatibility with old kernels
 402  * @lnum: logical eraseblock number to unmap
 403  * @padding: reserved for future, not used, has to be zeroed
 404  */
 405 struct ubi_map_req {
 406         __s32 lnum;
 407         __s8  dtype; /* obsolete, do not use! */
 408         __s8  padding[3];
 409 } __packed;
 410
 411
 412 /**
 413  * struct ubi_set_vol_prop_req - a data structure used to set an UBI volume
 414  *                               property.
 415  * @property: property to set (%UBI_VOL_PROP_DIRECT_WRITE)
 416  * @padding: reserved for future, not used, has to be zeroed
 417  * @value: value to set
 418  */
 419 struct ubi_set_vol_prop_req {
 420         __u8  property;
 421         __u8  padding[7];
 422         __u64 value;
 423 }  __packed;
 424
 425 /**
 426  * struct ubi_blkcreate_req - a data structure used in block creation requests.
 427  * @padding: reserved for future, not used, has to be zeroed
 428  */
 429 struct ubi_blkcreate_req {
 430         __s8  padding[128];
 431 }  __packed;
 432
 433 #endif /* __UBI_USER_H__ */