diff options
Diffstat (limited to 'u-boot/doc/README.nand')
| -rw-r--r-- | u-boot/doc/README.nand | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/u-boot/doc/README.nand b/u-boot/doc/README.nand new file mode 100644 index 0000000..8eedb6c --- /dev/null +++ b/u-boot/doc/README.nand @@ -0,0 +1,152 @@ +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. + +NOTE: +===== + +The current NAND implementation is based on what is in recent +Linux kernels. The old legacy implementation has been removed. + +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. |