UBI - Unsorted Block Images

UBI (Latin: "where?") manages multiple logical volumes on a single
flash device, specifically supporting NAND flash devices. UBI provides
a flexible partitioning concept which still allows for wear-levelling
across the whole flash device.

In a sense, UBI may be compared to the Logical Volume Manager
(LVM). Whereas LVM maps logical sector numbers to physical HDD sector
numbers, UBI maps logical eraseblocks to physical eraseblocks.

More information may be found in the UBI design documentation:
ubidesign.pdf. Which can be found here:
http://www.linux-mtd.infradead.org/doc/ubi.html

Partitioning/Re-partitioning

  An UBI volume occupies a certain number of erase blocks. This is
  limited by a configured maximum volume size, which could also be
  viewed as the partition size. Each individual UBI volume's size can
  be changed independently of the other UBI volumes, provided that the
  sum of all volume sizes doesn't exceed a certain limit.

  UBI supports dynamic volumes and static volumes. Static volumes are
  read-only and their contents are protected by CRC check sums.

Bad eraseblocks handling

  UBI transparently handles bad eraseblocks. When a physical
  eraseblock becomes bad, it is substituted by a good physical
  eraseblock, and the user does not even notice this.

Scrubbing

  On a NAND flash bit flips can occur on any write operation,
  sometimes also on read. If bit flips persist on the device, at first
  they can still be corrected by ECC, but once they accumulate,
  correction will become impossible. Thus it is best to actively scrub
  the affected eraseblock, by first copying it to a free eraseblock
  and then erasing the original. The UBI layer performs this type of
  scrubbing under the covers, transparently to the UBI volume users.

Erase Counts

  UBI maintains an erase count header per eraseblock. This frees
  higher-level layers (like file systems) from doing this and allows
  for centralized erase count management instead. The erase counts are
  used by the wear-levelling algorithm in the UBI layer. The algorithm
  itself is exchangeable.

Booting from NAND

  For booting directly from NAND flash the hardware must at least be
  capable of fetching and executing a small portion of the NAND
  flash. Some NAND flash controllers have this kind of support. They
  usually limit the window to a few kilobytes in erase block 0. This
  "initial program loader" (IPL) must then contain sufficient logic to
  load and execute the next boot phase.

  Due to bad eraseblocks, which may be randomly scattered over the
  flash device, it is problematic to store the "secondary program
  loader" (SPL) statically. Also, due to bit-flips it may become
  corrupted over time. UBI allows to solve this problem gracefully by
  storing the SPL in a small static UBI volume.

UBI volumes vs. static partitions

  UBI volumes are still very similar to static MTD partitions:

    * both consist of eraseblocks (logical eraseblocks in case of UBI
      volumes, and physical eraseblocks in case of static partitions;
    * both support three basic operations - read, write, erase.

  But UBI volumes have the following advantages over traditional
  static MTD partitions:

    * there are no eraseblock wear-leveling constraints in case of UBI
      volumes, so the user should not care about this;
    * there are no bit-flips and bad eraseblocks in case of UBI volumes.

  So, UBI volumes may be considered as flash devices with relaxed
  restrictions.

Where can it be found?

  Documentation, kernel code and applications can be found in the MTD
  gits.

What are the applications for?

  The applications help to create binary flash images for two
  purposes: pfi files (partial flash images) for in-system update of
  UBI volumes, and plain binary images, with or without OOB data in
  case of NAND, for a manufacturing step. Furthermore some tools
  are/and will be created that allow flash content analysis after a
  system has crashed.

Who did UBI?

  The original ideas, where UBI is based on, were developed by Andreas
  Arnez, Frank Haverkamp and Thomas Gleixner. Josh W. Boyer and
  some others were involved too. The implementation of the kernel
  layer was done by Artem B. Bityutskiy. The user-space applications
  and tools were written by Oliver Lohmann with contributions from
  Frank Haverkamp, Andreas Arnez, and Artem. Joern Engel contributed a
  patch which modifies JFFS2 so that it can be run on a UBI
  volume. Thomas Gleixner did modifications to the NAND layer and also
  some to JFFS2 to make it work.

Signed-off-by: Frank Haverkamp <haver@vnet.ibm.com>

1 files changed, 244 insertions, 0 deletions

diff --git a/ubi-utils/inc/pfi.h b/ubi-utils/inc/pfi.h
new file mode 100644
index 0000000..8c5cc07
--- /dev/null
+++ b/ubi-utils/inc/pfi.h
@@ -0,0 +1,244 @@
+#ifndef __pfi_h
+#define __pfi_h
+/*
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/**
+ * @file pfi.h
+ *
+ * @author Oliver Lohmann <oliloh@de.ibm.com>
+ *         Andreas Arnez <arnez@de.ibm.com>
+ *         Joern Engel <engeljoe@de.ibm.com>
+ *         Frank Haverkamp <haverkam@de.ibm.com>
+ *
+ * @brief libpfi will hold all code to create and process pfi
+ * images. Definitions made in this file are equaly usable for the
+ * development host and the target system.
+ *
+ * @note This header additionally holds the official definitions for
+ * the pfi headers.
+ */
+
+#include <stdio.h>		/* FILE */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Definitions. */
+
+#define PFI_HDRVERSION 1	/* current header version */
+
+#define PFI_ENOVERSION 1	/* unknown version */
+#define PFI_ENOHEADER  2	/* not a pfi header */
+#define PFI_EINSUFF    3	/* insufficient information */
+#define PFI_EUNDEF     4	/* key not defined */
+#define PFI_ENOMEM     5	/* out of memory */
+#define PFI_EBADTYPE   6	/* bad data type */
+#define PFI_EFILE      7	/* file I/O error: see errno */
+#define PFI_EFILEINVAL 8	/* file format not valid */
+#define PFI_EINVAL     9	/* invalid parameter */
+#define PFI_ERANGE     10	/* invalid range */
+#define PFI_EMODE      11	/* expecting other mode in this header */
+#define PFI_DATA_START 12	/* data section starts */
+#define PFI_EMAX       13	/* should be always larger as the largest
+				   error code */
+
+#define PFI_LABEL_LEN  64	/* This is the maximum length for a
+				   PFI header label */
+#define PFI_KEYWORD_LEN 32	/* This is the maximum length for an
+				   entry in the mode and type fields */
+
+#define PFI_UBI_MAX_VOLUMES 128
+#define PFI_UBI_VOL_NAME_LEN 127
+
+/**
+ * @brief The pfi header allows to set flags which influence the flashing
+ * behaviour.
+ */
+#define PFI_FLAG_PROTECTED   0x00000001
+
+
+/**
+ * @brief Handle to pfi header. Used in most of the functions associated
+ * with pfi file handling.
+ */
+typedef struct pfi_header *pfi_header;
+
+
+/**
+ * @brief Initialize a pfi header object.
+ *
+ * @param head	 Pointer to handle. This function allocates memory
+ *		 for this data structure.
+ * @return	 0 on success, otherwise:
+ *		 PFI_ENOMEM : no memory available for the handle.
+ */
+int pfi_header_init (pfi_header *head);
+
+
+/**
+ * @brief Destroy a pfi header object.
+ *
+ * @param head	 handle. head is invalid after calling this function.
+ * @return	 0 always.
+ */
+int pfi_header_destroy (pfi_header *head);
+
+
+/**
+ * @brief Add a key/value pair to a pfi header object.
+ *
+ * @param head	 handle.
+ * @param key	 pointer to key string. Must be 0 terminated.
+ * @param value	 pointer to value string. Must be 0 terminated.
+ * @return	 0 on success, otherwise:
+ *		 PFI_EUNDEF   : key was not found.
+ *		 PFI_ENOMEM   : no memory available for the handle.
+ *		 PFI_EBADTYPE : value is not an hex string. This happens
+ *				 when the key stores an integer and the
+ *				 new value is not convertable e.g. not in
+ *				 0xXXXXXXXX format.
+ */
+int pfi_header_setvalue (pfi_header head,
+			  const char *key, const char *value);
+
+
+/**
+ * @brief Add a key/value pair to a pfi header object. Provide the
+ * value as a number.
+ *
+ * @param head	 handle.
+ * @param key	 pointer to key string. Must be 0 terminated.
+ * @param value	 value to set.
+ * @return	 0 on success, otherwise:
+ *		 PFI_EUNDEF   : key was not found.
+ *		 PFI_EBADTYPE : value is not a string. This happens
+ *				 when the key stores a string.
+ */
+int pfi_header_setnumber (pfi_header head,
+			   const char *key, uint32_t value);
+
+
+/**
+ * @brief For a given key, return the numerical value stored in a
+ * pfi header object.
+ *
+ * @param head	 handle.
+ * @param key	 pointer to key string. Must be 0 terminated.
+ * @param value	 pointer to value.
+ * @return	 0 on success, otherwise:
+ *		 PFI_EUNDEF   : key was not found.
+ *		 PFI_EBADTYPE : stored value is not an integer but a string.
+ */
+int pfi_header_getnumber (pfi_header head,
+			   const char *key, uint32_t *value);
+
+
+static inline uint32_t
+pfi_getnumber(pfi_header head, const char *key)
+{
+	uint32_t value;
+	pfi_header_getnumber(head, key, &value);
+	return value;
+}
+
+/**
+ * @brief For a given key, return the string value stored in a pfi
+ * header object.
+ *
+ * @param head	 handle.
+ * @param key	 pointer to key string. Must be 0 terminated.
+ * @param value	 pointer to value string. Memory must be allocated by the user.
+ * @return	 0 on success, otherwise:
+ *		 PFI_EUNDEF   : key was not found.
+ *		 PFI_EBADTYPE : stored value is not a string but an integer.
+ */
+int pfi_header_getstring (pfi_header head,
+			   const char *key, char *value, size_t size);
+
+
+/**
+ * @brief Write a pfi header object into a given file.
+ *
+ * @param out	 output stream.
+ * @param head	 handle.
+ * @return	 0 on success, error values otherwise:
+ *		 PFI_EINSUFF   : not all mandatory fields are filled.
+ *		 PFI_ENOHEADER : wrong header version or magic number.
+ *		 -E*		: see <asm/errno.h>.
+ */
+int pfi_header_write (FILE *out, pfi_header head);
+
+
+/**
+ * @brief Read a pfi header object from a given file.
+ *
+ * @param in	 input stream.
+ * @param head	 handle.
+ * @return	 0 on success, error values otherwise:
+ *		 PFI_ENOVERSION: unknown header version.
+ *		 PFI_EFILE     : cannot read enough data.
+ *		 PFI_ENOHEADER : wrong header version or magic number.
+ *		 -E*		: see <asm/errno.h>.
+ *
+ * If the header verification returned success the user can assume that
+ * all mandatory fields for a particular version are accessible. Checking
+ * the return code when calling the get-function for those keys is not
+ * required in those cases. For optional fields the checking must still be
+ * done.
+ */
+int pfi_header_read (FILE *in, pfi_header head);
+
+
+/**
+ * @brief Display a pfi header in human-readable form.
+ *
+ * @param out	 output stream.
+ * @param head	 handle.
+ * @return	 always 0.
+ *
+ * @note Prints out that it is not implemented and whom you should
+ * contact if you need it urgently!.
+ */
+int pfi_header_dump (FILE *out, pfi_header head);
+
+
+/*
+ * @brief	 Iterates over a stream of pfi files. The iterator function
+ *		 must advance the file pointer in FILE *in to the next pfi
+ *		 header. Function exists on feof(in).
+ *
+ * @param in	 input file descriptor, must be open and valid.
+ * @param func	 iterator function called when pfi header could be
+ *		 read and was validated. The function must return 0 on
+ *		 success.
+ * @return	 See pfi_header_init and pfi_header_read.
+ *		 PFI_EINVAL	  : func is not valid
+ *		 0 ok.
+ */
+typedef int (* pfi_read_func)(FILE *in, pfi_header hdr, void *priv_data);
+
+int pfi_read (FILE *in, pfi_read_func func, void *priv_data);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __pfi_h */