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Legacy NAND is marked for feature removal after April 2009 (i.e. this upcoming release). There are still several boards that reference it (though many do so only for disk-on-chip support which has been silently disabled for a while now). These boards will now fail to build with #error, though the code is still there if the user removes #error. The plan is to remove the code outright in the next release, along with any board code that refers to it (such as board/esd/common/auto_update.c). Also, remove the legacy NAND API description from README.nand. Signed-off-by: Scott Wood <scottwood@freescale.com>
162 lines
6.1 KiB
Text
162 lines
6.1 KiB
Text
NAND FLASH commands and notes
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See NOTE below!!!
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# (C) Copyright 2003
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# Dave Ellis, SIXNET, dge@sixnetio.com
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#
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# See file CREDITS for list of people who contributed to this
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# project.
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License as
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# published by the Free Software Foundation; either version 2 of
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# the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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# MA 02111-1307 USA
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Commands:
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nand bad
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Print a list of all of the bad blocks in the current device.
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nand device
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Print information about the current NAND device.
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nand device num
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Make device `num' the current device and print information about it.
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nand erase off|partition size
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nand erase clean [off|partition size]
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Erase `size' bytes starting at offset `off'. Alternatively partition
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name can be specified, in this case size will be eventually limited
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to not exceed partition size (this behaviour applies also to read
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and write commands). Only complete erase blocks can be erased.
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If `erase' is specified without an offset or size, the entire flash
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is erased. If `erase' is specified with partition but without an
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size, the entire partition is erased.
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If `clean' is specified, a JFFS2-style clean marker is written to
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each block after it is erased.
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This command will not erase blocks that are marked bad. There is
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a debug option in cmd_nand.c to allow bad blocks to be erased.
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Please read the warning there before using it, as blocks marked
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bad by the manufacturer must _NEVER_ be erased.
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nand info
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Print information about all of the NAND devices found.
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nand read addr ofs|partition size
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Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that
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are marked bad are skipped. If a page cannot be read because an
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uncorrectable data error is found, the command stops with an error.
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nand read.oob addr ofs|partition size
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Read `size' bytes from the out-of-band data area corresponding to
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`ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
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data for one 512-byte page or 2 256-byte pages. There is no check
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for bad blocks or ECC errors.
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nand write addr ofs|partition size
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Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that
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are marked bad are skipped. If a page cannot be read because an
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uncorrectable data error is found, the command stops with an error.
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As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
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as long as the image is short enough to fit even after skipping the
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bad blocks. Compact images, such as those produced by mkfs.jffs2
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should work well, but loading an image copied from another flash is
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going to be trouble if there are any bad blocks.
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nand write.oob addr ofs|partition size
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Write `size' bytes from `addr' to the out-of-band data area
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corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
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of data for one 512-byte page or 2 256-byte pages. There is no check
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for bad blocks.
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Configuration Options:
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CONFIG_CMD_NAND
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Enables NAND support and commmands.
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CONFIG_MTD_NAND_ECC_JFFS2
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Define this if you want the Error Correction Code information in
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the out-of-band data to be formatted to match the JFFS2 file system.
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CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
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someone to implement.
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CONFIG_SYS_MAX_NAND_DEVICE
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The maximum number of NAND devices you want to support.
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CONFIG_SYS_NAND_MAX_CHIPS
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The maximum number of NAND chips per device to be supported.
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CONFIG_SYS_DAVINCI_BROKEN_ECC
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Versions of U-Boot <= 1.3.3 and Montavista Linux kernels
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generated bogus ECCs on large-page NAND. Both large and small page
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NAND ECCs were incompatible with the Linux davinci git tree (since
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NAND was integrated in 2.6.24).
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Turn this ON if you want backwards compatibility.
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Turn this OFF if you want U-Boot and the Linux davinci git kernel
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to use the same ECC format.
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NOTE:
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=====
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The current NAND implementation is based on what is in recent
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Linux kernels. The old legacy implementation has been disabled,
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and will be removed soon.
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If you have board code which used CONFIG_NAND_LEGACY, you'll need
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to convert to the current NAND interface for it to continue to work.
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The Disk On Chip driver is currently broken and has been for some time.
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There is a driver in drivers/mtd/nand, taken from Linux, that works with
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the current NAND system but has not yet been adapted to the u-boot
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environment.
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Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006
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JFFS2 related commands:
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implement "nand erase clean" and old "nand erase"
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using both the new code which is able to skip bad blocks
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"nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
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Miscellaneous and testing commands:
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"markbad [offset]"
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create an artificial bad block (for testing bad block handling)
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"scrub [offset length]"
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like "erase" but don't skip bad block. Instead erase them.
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DANGEROUS!!! Factory set bad blocks will be lost. Use only
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to remove artificial bad blocks created with the "markbad" command.
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NAND locking command (for chips with active LOCKPRE pin)
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"nand lock"
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set NAND chip to lock state (all pages locked)
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"nand lock tight"
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set NAND chip to lock tight state (software can't change locking anymore)
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"nand lock status"
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displays current locking status of all pages
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"nand unlock [offset] [size]"
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unlock consecutive area (can be called multiple times for different areas)
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I have tested the code with board containing 128MiB NAND large page chips
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and 32MiB small page chips.
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