README.nand 6.2 KB

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  1. NAND FLASH commands and notes
  2. See NOTE below!!!
  3. # (C) Copyright 2003
  4. # Dave Ellis, SIXNET, dge@sixnetio.com
  5. #
  6. # See file CREDITS for list of people who contributed to this
  7. # project.
  8. #
  9. # This program is free software; you can redistribute it and/or
  10. # modify it under the terms of the GNU General Public License as
  11. # published by the Free Software Foundation; either version 2 of
  12. # the License, or (at your option) any later version.
  13. #
  14. # This program is distributed in the hope that it will be useful,
  15. # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16. # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17. # GNU General Public License for more details.
  18. #
  19. # You should have received a copy of the GNU General Public License
  20. # along with this program; if not, write to the Free Software
  21. # Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22. # MA 02111-1307 USA
  23. Commands:
  24. nand bad
  25. Print a list of all of the bad blocks in the current device.
  26. nand device
  27. Print information about the current NAND device.
  28. nand device num
  29. Make device `num' the current device and print information about it.
  30. nand erase off|partition size
  31. nand erase clean [off|partition size]
  32. Erase `size' bytes starting at offset `off'. Alternatively partition
  33. name can be specified, in this case size will be eventually limited
  34. to not exceed partition size (this behaviour applies also to read
  35. and write commands). Only complete erase blocks can be erased.
  36. If `erase' is specified without an offset or size, the entire flash
  37. is erased. If `erase' is specified with partition but without an
  38. size, the entire partition is erased.
  39. If `clean' is specified, a JFFS2-style clean marker is written to
  40. each block after it is erased.
  41. This command will not erase blocks that are marked bad. There is
  42. a debug option in cmd_nand.c to allow bad blocks to be erased.
  43. Please read the warning there before using it, as blocks marked
  44. bad by the manufacturer must _NEVER_ be erased.
  45. nand info
  46. Print information about all of the NAND devices found.
  47. nand read addr ofs|partition size
  48. Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that
  49. are marked bad are skipped. If a page cannot be read because an
  50. uncorrectable data error is found, the command stops with an error.
  51. nand read.oob addr ofs|partition size
  52. Read `size' bytes from the out-of-band data area corresponding to
  53. `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
  54. data for one 512-byte page or 2 256-byte pages. There is no check
  55. for bad blocks or ECC errors.
  56. nand write addr ofs|partition size
  57. Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that
  58. are marked bad are skipped. If a page cannot be read because an
  59. uncorrectable data error is found, the command stops with an error.
  60. As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
  61. as long as the image is short enough to fit even after skipping the
  62. bad blocks. Compact images, such as those produced by mkfs.jffs2
  63. should work well, but loading an image copied from another flash is
  64. going to be trouble if there are any bad blocks.
  65. nand write.trimffs addr ofs|partition size
  66. Enabled by the CONFIG_CMD_NAND_TRIMFFS macro. This command will write to
  67. the NAND flash in a manner identical to the 'nand write' command
  68. described above -- with the additional check that all pages at the end
  69. of eraseblocks which contain only 0xff data will not be written to the
  70. NAND flash. This behaviour is required when flashing UBI images
  71. containing UBIFS volumes as per the UBI FAQ[1].
  72. [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo
  73. nand write.oob addr ofs|partition size
  74. Write `size' bytes from `addr' to the out-of-band data area
  75. corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
  76. of data for one 512-byte page or 2 256-byte pages. There is no check
  77. for bad blocks.
  78. Configuration Options:
  79. CONFIG_CMD_NAND
  80. Enables NAND support and commmands.
  81. CONFIG_MTD_NAND_ECC_JFFS2
  82. Define this if you want the Error Correction Code information in
  83. the out-of-band data to be formatted to match the JFFS2 file system.
  84. CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
  85. someone to implement.
  86. CONFIG_SYS_MAX_NAND_DEVICE
  87. The maximum number of NAND devices you want to support.
  88. CONFIG_SYS_NAND_MAX_CHIPS
  89. The maximum number of NAND chips per device to be supported.
  90. NOTE:
  91. =====
  92. The current NAND implementation is based on what is in recent
  93. Linux kernels. The old legacy implementation has been removed.
  94. If you have board code which used CONFIG_NAND_LEGACY, you'll need
  95. to convert to the current NAND interface for it to continue to work.
  96. The Disk On Chip driver is currently broken and has been for some time.
  97. There is a driver in drivers/mtd/nand, taken from Linux, that works with
  98. the current NAND system but has not yet been adapted to the u-boot
  99. environment.
  100. Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006
  101. JFFS2 related commands:
  102. implement "nand erase clean" and old "nand erase"
  103. using both the new code which is able to skip bad blocks
  104. "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
  105. Miscellaneous and testing commands:
  106. "markbad [offset]"
  107. create an artificial bad block (for testing bad block handling)
  108. "scrub [offset length]"
  109. like "erase" but don't skip bad block. Instead erase them.
  110. DANGEROUS!!! Factory set bad blocks will be lost. Use only
  111. to remove artificial bad blocks created with the "markbad" command.
  112. NAND locking command (for chips with active LOCKPRE pin)
  113. "nand lock"
  114. set NAND chip to lock state (all pages locked)
  115. "nand lock tight"
  116. set NAND chip to lock tight state (software can't change locking anymore)
  117. "nand lock status"
  118. displays current locking status of all pages
  119. "nand unlock [offset] [size]"
  120. unlock consecutive area (can be called multiple times for different areas)
  121. I have tested the code with board containing 128MiB NAND large page chips
  122. and 32MiB small page chips.