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, 310 insertions, 0 deletions

diff --git a/ubi-utils/inc/libubi.h b/ubi-utils/inc/libubi.h
new file mode 100644
index 0000000..f13d812
--- /dev/null
+++ b/ubi-utils/inc/libubi.h
@@ -0,0 +1,310 @@
+#ifndef __UBI_H__
+#define __UBI_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.
+ */
+
+/*
+ * UBI (Unsorted Block Images) library.
+ * @file	libubi.h
+ * @author	Artem B. Bityutskiy
+ * @author      Additions: Oliver Lohmann
+ * @version	1.0
+ */
+
+#include <stdint.h>
+#include <mtd/ubi-user.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @section eh Error Handling
+ * The following error indication policy is used: in case of success, all
+ * library functions return 0, in case of failure they either return UBI error
+ * codes, or -1 if a system error occured; in the latter case the exact error
+ * code has to be in the errno variable.
+ *
+ * @def UBI_ENOTFOUND
+ *	@brief UBI was not found in the system.
+ * @def UBI_EBUG
+ *	@brief An error due to bug in kernel part of UBI in UBI library.
+ * @def UBI_EINVAL
+ *	@brief Invalid argument.
+ * @def UBI_EMACS
+ *	@brief Highest error value.
+ */
+#define UBI_ENOTFOUND	1
+#define UBI_EBUG	2
+#define UBI_EINVAL	3
+#define UBI_EMAX	4
+
+
+/**
+ * UBI library descriptor, vague for library users.
+ */
+typedef struct ubi_lib *ubi_lib_t;
+
+/**
+ * struct ubi_info - general information about UBI.
+ *
+ * @version    UBI version
+ * @nlen_max   maximum length of names of volumes
+ * @dev_count  count UBI devices in the system
+ */
+struct ubi_info
+{
+	unsigned int version;
+	unsigned int nlen_max;
+	unsigned int dev_count;
+};
+
+/**
+ * struct ubi_dev_info - information about an UBI device
+ *
+ * @wear       average number of erasures of flash erasable blocks
+ * @major      major number of the corresponding character device
+ * @minor      minor number of the corresponding character device
+ * @eb_size    size of eraseblocks
+ * @total_ebs  total count of eraseblocks
+ * @avail_ebs  count of unused eraseblock available for new volumes
+ * @vol_count  total count of volumes in this UBI device
+ */
+struct ubi_dev_info
+{
+	unsigned long long wear;
+	unsigned int major;
+	unsigned int minor;
+	unsigned int eb_size;
+	unsigned int total_ebs;
+	unsigned int avail_ebs;
+	unsigned int vol_count;
+};
+
+/**
+ * struct ubi_vol_info - information about an UBI volume
+ *
+ * @bytes        volume size in bytes
+ * @eraseblocks  volume size in eraseblocks
+ * @major        major number of the corresponding character device
+ * @minor        minor number of the corresponding character device
+ * @type         volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @dev_path	 device path to volume
+ * @name         volume name
+ */
+struct ubi_vol_info
+{
+	unsigned long long bytes;
+	unsigned int eraseblocks;
+	unsigned int major;
+	unsigned int minor;
+	int type;
+	char *dev_path;
+	char *name;
+};
+
+/**
+ * ubi_mkvol - create a dynamic UBI volume.
+ *
+ * @desc       UBI library descriptor
+ * @devn       Number of UBI device to create new volume on
+ * @vol_id     volume ID to assign to the new volume
+ * @vol_type   volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @bytes      volume size in bytes
+ * @alignment  volume alignment
+ * @name       volume name
+ *
+ * This function creates new UBI volume. If @vol_id is %UBI_VOLN_AUTO, then
+ * volume number is assigned automatically. This function returns positive
+ * volume number of the new volume in case of success or %-1 in case of
+ * failure.
+ */
+int ubi_mkvol(ubi_lib_t desc, int devn, int vol_id, int vol_type,
+	      long long bytes, int alignment, const char *name);
+
+/**
+ * ubi_rmvol - remove a volume.
+ *
+ * @desc       UBI library descriptor
+ * @devn       Number of UBI device to remove volume from
+ * @vol_id     volume ID to remove
+ *
+ * This function returns zero in case of success or %-1 in case of failure.
+ */
+int ubi_rmvol(ubi_lib_t desc, int devn, int vol_id);
+
+/**
+ * ubi_get_info - get UBI information.
+ *
+ * @desc  UBI library descriptor
+ * @ubi   UBI information is returned here
+ *
+ * This function retrieves information about UBI and puts it to @ubi. Returns
+ * zero in case of success and %-1 in case of failure.
+ */
+int ubi_get_info(ubi_lib_t desc, struct ubi_info *ubi);
+
+/**
+ * ubi_vol_open - open a UBI volume
+ *
+ * @desc	UBI library descriptor
+ * @devn	Number of UBI device on which to open the volume
+ * @vol_id	Number of UBI device on which to open the volume
+ * @flags	Flags to pass to open()
+ *
+ * This function opens a UBI volume on a given UBI device.  It returns
+ * the file descriptor of the opened volume device.  In case of an
+ * error %-1 is returned and errno is set appropriately.
+ */
+int ubi_vol_open(ubi_lib_t desc, int devn, int vol_id, int flags);
+
+/**
+ * ubi_vol_close - close a UBI volume
+ *
+ * @vol_fd	file descriptor of UBI volume to close
+ *
+ * This function closes the given UBI device.
+ */
+int ubi_vol_close(int vol_fd);
+
+/**
+ * ubi_vol_update - initiate volume update on a UBI volume
+ * @vol_fd	File descriptor of UBI volume to update
+ * @bytes	No. of bytes which shall be written.
+ *
+ * Initiates a volume update on a given volume.  The caller must then
+ * actually write the appropriate number of bytes to the volume by
+ * calling write().  Returns 0 on success, else error.
+ */
+int ubi_vol_update(int vol_fd, unsigned long long bytes);
+
+/**
+ * ubi_vol_fopen_read - open a volume for reading, returning a FILE *
+ * @desc	UBI library descriptor
+ * @devn	UBI device number
+ * @vol_id	volume ID to read
+ *
+ * Opens a volume for reading.  Reading itself can then be performed
+ * with fread().  The stream can be closed with fclose().  Returns a
+ * stream on success, else NULL.
+ */
+FILE *
+ubi_vol_fopen_read(ubi_lib_t desc, int devn, uint32_t vol_id);
+
+/**
+ * ubi_vol_fopen_update - open a volume for writing, returning a FILE *
+ * @desc	UBI library descriptor
+ * @devn	UBI device number
+ * @vol_id	volume ID to update
+ * @bytes	No. of bytes which shall be written.
+ *
+ * Initiates a volume update on a given volume.  The caller must then
+ * actually write the appropriate number of bytes to the volume by
+ * calling fwrite().  The file can be closed with fclose().  Returns a
+ * stream on success, else NULL.
+ */
+FILE *
+ubi_vol_fopen_update(ubi_lib_t desc, int devn, uint32_t vol_id,
+		     unsigned long long bytes);
+
+/**
+ * ubi_vol_get_used_bytes - determine used bytes in a UBI volume
+ * @vol_fd	File descriptor of UBI volume
+ * @bytes	Pointer to result
+ *
+ * Returns 0 on success, else error.
+ */
+int ubi_vol_get_used_bytes(int vol_fd, unsigned long long *bytes);
+
+/**
+ * ubi_open - open UBI library.
+ *
+ * @desc  A pointer to an UBI library descriptor
+ *
+ * Returns zero in case of success.
+ */
+int ubi_open(ubi_lib_t *desc);
+
+/**
+ * ubi_close - close UBI library.
+ *
+ * @desc  A pointer to an UBI library descriptor
+ */
+int ubi_close(ubi_lib_t *desc);
+
+
+/**
+ * ubi_perror - print UBI error.
+ *
+ * @prefix  a prefix string to prepend to the error message
+ * @code    error code
+ *
+ * If @code is %-1, this function calls 'perror()'
+ */
+void ubi_perror(const char *prefix, int code);
+
+/**
+ * ubi_set_cdev_pattern - set 'sprintf()'-like pattern of paths to UBI
+ * character devices.
+ *
+ * @desc     UBI library descriptor
+ * @pattern  the pattern to set
+ *
+ * The default UBI character device path is "/dev/ubi%u".
+ */
+int ubi_set_cdev_pattern(ubi_lib_t desc, const char *pattern);
+
+/**
+ * ubi_get_dev_info get information about an UBI device.
+ *
+ * @desc  UBI library descriptor
+ * @devn  UBI device number
+ * @di    the requested information is returned here
+ */
+int ubi_get_dev_info(ubi_lib_t desc, unsigned int devn,
+		struct ubi_dev_info *di);
+
+/**
+ * ubi_set_vol_cdev_pattern - set 'sprintf()'-like pattµern ofpaths to UBI
+ * volume character devices.
+ *
+ * @desc     UBI library descriptor
+ * @pattern  the pattern to set
+ *
+ * The default UBI character device path is "/dev/ubi%u_%u".
+ */
+int ubi_set_vol_cdev_pattern(ubi_lib_t desc, const char *pattern);
+
+/**
+ * ubi_get_vol_info - get information about an UBI volume
+ *
+ * @desc  UBI library descriptor
+ * @devn  UBI device number the volume belongs to
+ * @vol_id  the requested volume number
+ * @vi    volume information is returned here
+ *
+ * Users must free the volume name string @vi->name.
+ */
+int ubi_get_vol_info(ubi_lib_t desc, unsigned int devn, unsigned int vol_id,
+		struct ubi_vol_info *vi);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !__UBI_H__ */