doc/README.nand - platform/external/u-boot - Gitiles

 NAND FLASH commands and notes

 See NOTE below!!!

 # (C) Copyright 2003
 # Dave Ellis, SIXNET, dge@sixnetio.com
 #
 # See file CREDITS for list of people who contributed to this
 # project.
 #
 # 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

 Commands:

    nand bad
       Print a list of all of the bad blocks in the current device.

    nand device
       Print information about the current NAND device.

    nand device num
       Make device `num' the current device and print information about it.

    nand erase off|partition size
    nand erase clean [off|partition size]
       Erase `size' bytes starting at offset `off'. Alternatively partition
       name can be specified, in this case size will be eventually limited
       to not exceed partition size (this behaviour applies also to read
       and write commands). Only complete erase blocks can be erased.

       If `erase' is specified without an offset or size, the entire flash
       is erased. If `erase' is specified with partition but without an
       size, the entire partition is erased.

       If `clean' is specified, a JFFS2-style clean marker is written to
       each block after it is erased.

       This command will not erase blocks that are marked bad. There is
       a debug option in cmd_nand.c to allow bad blocks to be erased.
       Please read the warning there before using it, as blocks marked
       bad by the manufacturer must _NEVER_ be erased.

    nand info
       Print information about all of the NAND devices found.

    nand read addr ofs|partition size
       Read `size' bytes from `ofs' in NAND flash to `addr'.  Blocks that
       are marked bad are skipped.  If a page cannot be read because an
       uncorrectable data error is found, the command stops with an error.

    nand read.oob addr ofs|partition size
       Read `size' bytes from the out-of-band data area corresponding to
       `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
       data for one 512-byte page or 2 256-byte pages. There is no check
       for bad blocks or ECC errors.

    nand write addr ofs|partition size
       Write `size' bytes from `addr' to `ofs' in NAND flash.  Blocks that
       are marked bad are skipped.  If a page cannot be read because an
       uncorrectable data error is found, the command stops with an error.

       As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
       as long as the image is short enough to fit even after skipping the
       bad blocks.  Compact images, such as those produced by mkfs.jffs2
       should work well, but loading an image copied from another flash is
       going to be trouble if there are any bad blocks.

    nand write.oob addr ofs|partition size
       Write `size' bytes from `addr' to the out-of-band data area
       corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
       of data for one 512-byte page or 2 256-byte pages. There is no check
       for bad blocks.

 Configuration Options:

    CONFIG_CMD_NAND
       Enables NAND support and commmands.

    CONFIG_MTD_NAND_ECC_JFFS2
       Define this if you want the Error Correction Code information in
       the out-of-band data to be formatted to match the JFFS2 file system.
       CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
       someone to implement.

    CONFIG_SYS_MAX_NAND_DEVICE
       The maximum number of NAND devices you want to support.

    CONFIG_SYS_NAND_MAX_CHIPS
       The maximum number of NAND chips per device to be supported.

    CONFIG_SYS_DAVINCI_BROKEN_ECC
       Versions of U-Boot <= 1.3.3 and Montavista Linux kernels
       generated bogus ECCs on large-page NAND. Both large and small page
       NAND ECCs were incompatible with the Linux davinci git tree (since
       NAND was integrated in 2.6.24).
       Turn this ON if you want backwards compatibility.
       Turn this OFF if you want U-Boot and the Linux davinci git kernel
       to use the same ECC format.

 NOTE:
 =====

 The current NAND implementation is based on what is in recent
 Linux kernels.  The old legacy implementation has been disabled,
 and will be removed soon.

 If you have board code which used CONFIG_NAND_LEGACY, you'll need
 to convert to the current NAND interface for it to continue to work.

 The Disk On Chip driver is currently broken and has been for some time.
 There is a driver in drivers/mtd/nand, taken from Linux, that works with
 the current NAND system but has not yet been adapted to the u-boot
 environment.

 Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006

 JFFS2 related commands:

   implement "nand erase clean" and old "nand erase"
   using both the new code which is able to skip bad blocks
   "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.

 Miscellaneous and testing commands:
   "markbad [offset]"
   create an artificial bad block (for testing bad block handling)

   "scrub [offset length]"
   like "erase" but don't skip bad block. Instead erase them.
   DANGEROUS!!! Factory set bad blocks will be lost. Use only
   to remove artificial bad blocks created with the "markbad" command.


 NAND locking command (for chips with active LOCKPRE pin)

   "nand lock"
   set NAND chip to lock state (all pages locked)

   "nand lock tight"
   set NAND chip to lock tight state (software can't change locking anymore)

   "nand lock status"
   displays current locking status of all pages

   "nand unlock [offset] [size]"
   unlock consecutive area (can be called multiple times for different areas)


 I have tested the code with board containing 128MiB NAND large page chips
 and 32MiB small page chips.
	NAND FLASH commands and notes

	See NOTE below!!!

	# (C) Copyright 2003
	# Dave Ellis, SIXNET, dge@sixnetio.com
	#
	# See file CREDITS for list of people who contributed to this
	# project.
	#
	# 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

	Commands:

	nand bad
	Print a list of all of the bad blocks in the current device.

	nand device
	Print information about the current NAND device.

	nand device num
	Make device `num' the current device and print information about it.

	nand erase off\|partition size
	nand erase clean [off\|partition size]
	Erase `size' bytes starting at offset `off'. Alternatively partition
	name can be specified, in this case size will be eventually limited
	to not exceed partition size (this behaviour applies also to read
	and write commands). Only complete erase blocks can be erased.

	If `erase' is specified without an offset or size, the entire flash
	is erased. If `erase' is specified with partition but without an
	size, the entire partition is erased.

	If `clean' is specified, a JFFS2-style clean marker is written to
	each block after it is erased.

	This command will not erase blocks that are marked bad. There is
	a debug option in cmd_nand.c to allow bad blocks to be erased.
	Please read the warning there before using it, as blocks marked
	bad by the manufacturer must _NEVER_ be erased.

	nand info
	Print information about all of the NAND devices found.

	nand read addr ofs\|partition size
	Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that
	are marked bad are skipped. If a page cannot be read because an
	uncorrectable data error is found, the command stops with an error.

	nand read.oob addr ofs\|partition size
	Read `size' bytes from the out-of-band data area corresponding to
	`ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
	data for one 512-byte page or 2 256-byte pages. There is no check
	for bad blocks or ECC errors.

	nand write addr ofs\|partition size
	Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that
	are marked bad are skipped. If a page cannot be read because an
	uncorrectable data error is found, the command stops with an error.

	As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
	as long as the image is short enough to fit even after skipping the
	bad blocks. Compact images, such as those produced by mkfs.jffs2
	should work well, but loading an image copied from another flash is
	going to be trouble if there are any bad blocks.

	nand write.oob addr ofs\|partition size
	Write `size' bytes from `addr' to the out-of-band data area
	corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
	of data for one 512-byte page or 2 256-byte pages. There is no check
	for bad blocks.

	Configuration Options:

	CONFIG_CMD_NAND
	Enables NAND support and commmands.

	CONFIG_MTD_NAND_ECC_JFFS2
	Define this if you want the Error Correction Code information in
	the out-of-band data to be formatted to match the JFFS2 file system.
	CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
	someone to implement.

	CONFIG_SYS_MAX_NAND_DEVICE
	The maximum number of NAND devices you want to support.

	CONFIG_SYS_NAND_MAX_CHIPS
	The maximum number of NAND chips per device to be supported.

	CONFIG_SYS_DAVINCI_BROKEN_ECC
	Versions of U-Boot <= 1.3.3 and Montavista Linux kernels
	generated bogus ECCs on large-page NAND. Both large and small page
	NAND ECCs were incompatible with the Linux davinci git tree (since
	NAND was integrated in 2.6.24).
	Turn this ON if you want backwards compatibility.
	Turn this OFF if you want U-Boot and the Linux davinci git kernel
	to use the same ECC format.

	NOTE:
	=====

	The current NAND implementation is based on what is in recent
	Linux kernels. The old legacy implementation has been disabled,
	and will be removed soon.

	If you have board code which used CONFIG_NAND_LEGACY, you'll need
	to convert to the current NAND interface for it to continue to work.

	The Disk On Chip driver is currently broken and has been for some time.
	There is a driver in drivers/mtd/nand, taken from Linux, that works with
	the current NAND system but has not yet been adapted to the u-boot
	environment.

	Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006

	JFFS2 related commands:

	implement "nand erase clean" and old "nand erase"
	using both the new code which is able to skip bad blocks
	"nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.

	Miscellaneous and testing commands:
	"markbad [offset]"
	create an artificial bad block (for testing bad block handling)

	"scrub [offset length]"
	like "erase" but don't skip bad block. Instead erase them.
	DANGEROUS!!! Factory set bad blocks will be lost. Use only
	to remove artificial bad blocks created with the "markbad" command.


	NAND locking command (for chips with active LOCKPRE pin)

	"nand lock"
	set NAND chip to lock state (all pages locked)

	"nand lock tight"
	set NAND chip to lock tight state (software can't change locking anymore)

	"nand lock status"
	displays current locking status of all pages

	"nand unlock [offset] [size]"
	unlock consecutive area (can be called multiple times for different areas)


	I have tested the code with board containing 128MiB NAND large page chips
	and 32MiB small page chips.