/*
   * 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 Bityutskiy (Битюцкий Артём)
   *          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_MEDIA_H__
  #define __UBI_MEDIA_H__
  
  #include <asm/byteorder.h>
  
  /* The version of UBI images supported by this implementation */
  #define UBI_VERSION 1
  
  /* The highest erase counter value supported by this implementation */
  #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
  
  /* The initial CRC32 value used when calculating CRC checksums */
  #define UBI_CRC32_INIT 0xFFFFFFFFU
  
  /* Erase counter header magic number (ASCII "UBI#") */
  #define UBI_EC_HDR_MAGIC  0x55424923
  /* Volume identifier header magic number (ASCII "UBI!") */
  #define UBI_VID_HDR_MAGIC 0x55424921
  
  /*
   * Volume type constants used in the volume identifier header.
   *
   * @UBI_VID_DYNAMIC: dynamic volume
   * @UBI_VID_STATIC: static volume
   */
  enum {
  	UBI_VID_DYNAMIC = 1,
  	UBI_VID_STATIC  = 2
  };
  
  /*
   * Volume flags used in the volume table record.
   *
   * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
   *
   * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
   * table. UBI automatically re-sizes the volume which has this flag and makes
   * the volume to be of largest possible size. This means that if after the
   * initialization UBI finds out that there are available physical eraseblocks
   * present on the device, it automatically appends all of them to the volume
   * (the physical eraseblocks reserved for bad eraseblocks handling and other
   * reserved physical eraseblocks are not taken). So, if there is a volume with
   * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
   * eraseblocks will be zero after UBI is loaded, because all of them will be
   * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
   * after the volume had been initialized.
   *
   * The auto-resize feature is useful for device production purposes. For
   * example, different NAND flash chips may have different amount of initial bad
   * eraseblocks, depending of particular chip instance. Manufacturers of NAND
   * chips usually guarantee that the amount of initial bad eraseblocks does not
   * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
   * flashed to the end devices in production, he does not know the exact amount
   * of good physical eraseblocks the NAND chip on the device will have, but this
   * number is required to calculate the volume sized and put them to the volume
   * table of the UBI image. In this case, one of the volumes (e.g., the one
   * which will store the root file system) is marked as "auto-resizable", and
   * UBI will adjust its size on the first boot if needed.
   *
   * Note, first UBI reserves some amount of physical eraseblocks for bad
   * eraseblock handling, and then re-sizes the volume, not vice-versa. This
   * means that the pool of reserved physical eraseblocks will always be present.
   */
  enum {
  	UBI_VTBL_AUTORESIZE_FLG = 0x01,
  };
  
  /*
   * 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_PRESERVE: preserve this internal volume - do not touch its
   *                       physical eraseblocks, don't allow the wear-leveling
   *                       sub-system to move them
   * @UBI_COMPAT_REJECT: reject this UBI image
   */
  enum {
  	UBI_COMPAT_DELETE   = 1,
  	UBI_COMPAT_RO       = 2,
  	UBI_COMPAT_PRESERVE = 4,
  	UBI_COMPAT_REJECT   = 5
  };
  
  /* 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(__be32))
  #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
  
  /**
   * struct ubi_ec_hdr - UBI erase counter header.
   * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
   * @version: version of UBI implementation which is supposed to accept this
   *           UBI image
   * @padding1: reserved for future, zeroes
   * @ec: the erase counter
   * @vid_hdr_offset: where the VID header starts
   * @data_offset: where the user data start
   * @image_seq: image sequence number
   * @padding2: reserved for future, zeroes
   * @hdr_crc: 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 than the current UBI
   * version, the image is rejected. 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
   * physical eraseblock. These values have to be the same for all physical
   * eraseblocks.
   *
   * The @image_seq field is used to validate a UBI image that has been prepared
   * for a UBI device. The @image_seq value can be any value, but it must be the
   * same on all eraseblocks. UBI will ensure that all new erase counter headers
   * also contain this value, and will check the value when attaching the flash.
   * One way to make use of @image_seq is to increase its value by one every time
   * an image is flashed over an existing image, then, if the flashing does not
   * complete, UBI will detect the error when attaching the media.
   */
  struct ubi_ec_hdr {
  	__be32  magic;
  	__u8    version;
  	__u8    padding1[3];
  	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
  	__be32  vid_hdr_offset;
  	__be32  data_offset;
  	__be32  image_seq;
  	__u8    padding2[32];
  	__be32  hdr_crc;
  } __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: if this logical eraseblock was copied from another physical
   *             eraseblock (for wear-leveling reasons)
   * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
   *          %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
   * @vol_id: ID of this volume
   * @lnum: logical eraseblock number
   * @padding1: reserved for future, zeroes
   * @data_size: how many bytes of data this logical eraseblock contains
   * @used_ebs: total number of used logical eraseblocks in this volume
   * @data_pad: how many bytes at the end of this physical eraseblock are not
   *            used
   * @data_crc: CRC checksum of the data stored in this logical eraseblock
   * @padding2: reserved for future, zeroes
   * @sqnum: sequence number
   * @padding3: reserved for future, zeroes
   * @hdr_crc: volume identifier header CRC checksum
   *
   * The @sqnum is the value of the global sequence counter at the time when this
   * VID header was created. The global sequence counter is incremented each time
   * UBI writes a new VID header to the flash, i.e. when it maps a logical
   * eraseblock to a new physical eraseblock. The global sequence counter is an
   * unsigned 64-bit integer and we assume it never overflows. The @sqnum
   * (sequence number) is used to distinguish between older and newer versions of
   * logical eraseblocks.
   *
   * There are 2 situations when there may be more than one physical eraseblock
   * corresponding to the same logical eraseblock, i.e., having the same @vol_id
   * and @lnum values in the volume identifier header. Suppose we have a logical
   * eraseblock L and it is mapped to the physical eraseblock P.
   *
   * 1. Because UBI may erase physical eraseblocks asynchronously, the following
   * situation is possible: L is asynchronously erased, so P is scheduled for
   * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
   * so P1 is written to, then an unclean reboot happens. Result - there are 2
   * physical eraseblocks P and P1 corresponding to the same logical eraseblock
   * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
   * flash.
   *
   * 2. From time to time UBI moves logical eraseblocks to other physical
   * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
   * to P1, and an unclean reboot happens before P is physically erased, there
   * are two physical eraseblocks P and P1 corresponding to L and UBI has to
   * select one of them when the flash is attached. The @sqnum field says which
   * PEB is the original (obviously P will have lower @sqnum) and the copy. But
   * it is not enough to select the physical eraseblock with the higher sequence
   * number, because the unclean reboot could have happen in the middle of the
   * copying process, so the data in P is corrupted. It is also not enough to
   * just select the physical eraseblock with lower sequence number, because the
   * data there may be old (consider a case if more data was added to P1 after
   * the copying). Moreover, the unclean reboot may happen when the erasure of P
   * was just started, so it result in unstable P, which is "mostly" OK, but
   * still has unstable bits.
   *
   * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
   * copy. UBI also calculates data CRC when the data is moved and stores it at
   * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
   * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
   * examined. If it is cleared, the situation* is simple and the newer one is
   * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
   * checksum is correct, this physical eraseblock is selected (P1). Otherwise
   * the older one (P) is selected.
   *
   * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
   * Internal volumes are not seen from outside and are used for various internal
   * UBI purposes. In this implementation there is only one internal volume - the
   * layout volume. Internal volumes are the main mechanism of UBI extensions.
   * For example, in future one may introduce a journal internal volume. Internal
   * volumes have their own reserved range of IDs.
   *
   * The @compat field is only used for internal volumes and contains the "degree
   * of their compatibility". It 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 a journal in
   * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
   * journal volume.  And in this case, older UBI binaries, which know nothing
   * about the journal volume, would just delete this volume and work perfectly
   * fine. This is 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
   * data of the physical eraseblock was moved by the wear-leveling sub-system,
   * then the wear-leveling sub-system calculates the data CRC and stores it in
   * the @data_crc field. And of course, the @copy_flag is %in this case.
   *
   * The @data_size field is used only for static volumes because UBI has to know
   * how many bytes of data are stored in this eraseblock. For dynamic volumes,
   * this field usually contains zero. The only exception is when the data of the
   * physical eraseblock was moved to another physical eraseblock for
   * 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 data size.
   *
   * 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.
   */
  struct ubi_vid_hdr {
  	__be32  magic;
  	__u8    version;
  	__u8    vol_type;
  	__u8    copy_flag;
  	__u8    compat;
  	__be32  vol_id;
  	__be32  lnum;
  	__u8    padding1[4];
  	__be32  data_size;
  	__be32  used_ebs;
  	__be32  data_pad;
  	__be32  data_crc;
  	__u8    padding2[4];
  	__be64  sqnum;
  	__u8    padding3[12];
  	__be32  hdr_crc;
  } __packed;
  
  /* Internal UBI volumes count */
  #define UBI_INT_VOL_COUNT 1
  
  /*
   * Starting ID of internal volumes: 0x7fffefff.
   * There is reserved room for 4096 internal volumes.
   */
  #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
  
  /* The layout volume contains the volume table */
  
  #define UBI_LAYOUT_VOLUME_ID     UBI_INTERNAL_VOL_START
  #define UBI_LAYOUT_VOLUME_TYPE   UBI_VID_DYNAMIC
  #define UBI_LAYOUT_VOLUME_ALIGN  1
  #define UBI_LAYOUT_VOLUME_EBS    2
  #define UBI_LAYOUT_VOLUME_NAME   "layout volume"
  #define UBI_LAYOUT_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 the volume table record */
  #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
  
  /* Size of the volume table record without the ending CRC */
  #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
  
  /**
   * struct ubi_vtbl_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 unused at the end of the each physical
   * eraseblock to satisfy the requested alignment
   * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
   * @upd_marker: if volume update was started but not finished
   * @name_len: volume name length
   * @name: the volume name
   * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
   * @padding: reserved, zeroes
   * @crc: a CRC32 checksum of the record
   *
   * The volume table records are stored in the volume table, which is stored in
   * the layout volume. The layout volume consists of 2 logical eraseblock, each
   * of which contains a copy of the volume table (i.e., the volume table is
   * duplicated). The volume table is an array of &struct ubi_vtbl_record
   * objects indexed by the volume ID.
   *
   * If the size of the logical eraseblock is large enough to fit
   * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
   * records. Otherwise, it contains as many records as it can fit (i.e., size of
   * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
   *
   * The @upd_marker flag is used to implement volume update. It is set to %1
   * before update and set to %0 after the update. So if the update operation was
   * interrupted, UBI knows that the volume is corrupted.
   *
   * 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
   * the physical eraseblocks is used.
   *
   * Empty records contain all zeroes and the CRC checksum of those zeroes.
   */
  struct ubi_vtbl_record {
  	__be32  reserved_pebs;
  	__be32  alignment;
  	__be32  data_pad;
  	__u8    vol_type;
  	__u8    upd_marker;
  	__be16  name_len;
  	__u8    name[UBI_VOL_NAME_MAX+1];
  	__u8    flags;
  	__u8    padding[23];
  	__be32  crc;
  } __packed;
  
  /* UBI fastmap on-flash data structures */
  
  #define UBI_FM_SB_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 1)
  #define UBI_FM_DATA_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 2)
  
  /* fastmap on-flash data structure format version */
  #define UBI_FM_FMT_VERSION	1
  
  #define UBI_FM_SB_MAGIC		0x7B11D69F
  #define UBI_FM_HDR_MAGIC	0xD4B82EF7
  #define UBI_FM_VHDR_MAGIC	0xFA370ED1
  #define UBI_FM_POOL_MAGIC	0x67AF4D08
  #define UBI_FM_EBA_MAGIC	0xf0c040a8
  
  /* A fastmap supber block can be located between PEB 0 and
   * UBI_FM_MAX_START */
  #define UBI_FM_MAX_START	64
  
  /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
  #define UBI_FM_MAX_BLOCKS	32
  
  /* 5% of the total number of PEBs have to be scanned while attaching
   * from a fastmap.
   * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
   * UBI_FM_MAX_POOL_SIZE */
  #define UBI_FM_MIN_POOL_SIZE	8
  #define UBI_FM_MAX_POOL_SIZE	256
  
  /**
   * struct ubi_fm_sb - UBI fastmap super block
   * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
   * @version: format version of this fastmap
   * @data_crc: CRC over the fastmap data
   * @used_blocks: number of PEBs used by this fastmap
   * @block_loc: an array containing the location of all PEBs of the fastmap
   * @block_ec: the erase counter of each used PEB
   * @sqnum: highest sequence number value at the time while taking the fastmap
   *
   */
  struct ubi_fm_sb {
  	__be32 magic;
  	__u8 version;
  	__u8 padding1[3];
  	__be32 data_crc;
  	__be32 used_blocks;
  	__be32 block_loc[UBI_FM_MAX_BLOCKS];
  	__be32 block_ec[UBI_FM_MAX_BLOCKS];
  	__be64 sqnum;
  	__u8 padding2[32];
  } __packed;
  
  /**
   * struct ubi_fm_hdr - header of the fastmap data set
   * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
   * @free_peb_count: number of free PEBs known by this fastmap
   * @used_peb_count: number of used PEBs known by this fastmap
   * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
   * @bad_peb_count: number of bad PEBs known by this fastmap
   * @erase_peb_count: number of bad PEBs which have to be erased
   * @vol_count: number of UBI volumes known by this fastmap
   */
  struct ubi_fm_hdr {
  	__be32 magic;
  	__be32 free_peb_count;
  	__be32 used_peb_count;
  	__be32 scrub_peb_count;
  	__be32 bad_peb_count;
  	__be32 erase_peb_count;
  	__be32 vol_count;
  	__u8 padding[4];
  } __packed;
  
  /* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
  
  /**
   * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
   * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
   * @size: current pool size
   * @max_size: maximal pool size
   * @pebs: an array containing the location of all PEBs in this pool
   */
  struct ubi_fm_scan_pool {
  	__be32 magic;
  	__be16 size;
  	__be16 max_size;
  	__be32 pebs[UBI_FM_MAX_POOL_SIZE];
  	__be32 padding[4];
  } __packed;
  
  /* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
  
  /**
   * struct ubi_fm_ec - stores the erase counter of a PEB
   * @pnum: PEB number
   * @ec: ec of this PEB
   */
  struct ubi_fm_ec {
  	__be32 pnum;
  	__be32 ec;
  } __packed;
  
  /**
   * struct ubi_fm_volhdr - Fastmap volume header
   * it identifies the start of an eba table
   * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
   * @vol_id: volume id of the fastmapped volume
   * @vol_type: type of the fastmapped volume
   * @data_pad: data_pad value of the fastmapped volume
   * @used_ebs: number of used LEBs within this volume
   * @last_eb_bytes: number of bytes used in the last LEB
   */
  struct ubi_fm_volhdr {
  	__be32 magic;
  	__be32 vol_id;
  	__u8 vol_type;
  	__u8 padding1[3];
  	__be32 data_pad;
  	__be32 used_ebs;
  	__be32 last_eb_bytes;
  	__u8 padding2[8];
  } __packed;
  
  /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
  
  /**
   * struct ubi_fm_eba - denotes an association between a PEB and LEB
   * @magic: EBA table magic number
   * @reserved_pebs: number of table entries
   * @pnum: PEB number of LEB (LEB is the index)
   */
  struct ubi_fm_eba {
  	__be32 magic;
  	__be32 reserved_pebs;
  	__be32 pnum[0];
  } __packed;
  #endif /* !__UBI_MEDIA_H__ */