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+NAND FLASH commands and notes
+
+# (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 size
+ nand erase clean [off size]
+ Erase `size' bytes starting at offset `off'. Only complete erase
+ blocks can be erased.
+
+ If `clean' is specified, a JFFS2-style clean marker is written to
+ each block after it is erased. If `clean' is specified without an
+ offset or size, the entire flash 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 size
+ Read `size' bytes from `ofs' in NAND flash to `addr'. If a page
+ cannot be read because it is marked bad or an uncorrectable data
+ error is found the command stops with an error.
+
+ nand read.jffs2 addr ofs size
+ Like `read', but the data for blocks that are marked bad is read as
+ 0xff. This gives a readable JFFS2 image that can be processed by
+ the JFFS2 commands such as ls and fsload.
+
+ nand read.oob addr ofs 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 size
+ Write `size' bytes from `addr' to `ofs' in NAND flash. If a page
+ cannot be written because it is marked bad or the write fails the
+ command stops with an error.
+
+ nand write.jffs2 addr ofs size
+ Like `write', but blocks that are marked bad are skipped and the
+ is written to the next block instead. This allows writing 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 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:
+
+ CFG_CMD_NAND
+ A good one to add to CONFIG_COMMANDS since it enables NAND support.
+
+ 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.
+
+ CFG_MAX_NAND_DEVICE
+ The maximum number of NAND devices you want to support.
+
+NAND Interface:
+
+ #define NAND_WAIT_READY(nand)
+ Wait until the NAND flash is ready. Typically this would be a
+ loop waiting for the READY/BUSY line from the flash to indicate it
+ it is ready.
+
+ #define WRITE_NAND_COMMAND(d, adr)
+ Write the command byte `d' to the flash at `adr' with the
+ CLE (command latch enable) line true. If your board uses writes to
+ different addresses to control CLE and ALE, you can modify `adr'
+ to be the appropriate address here. If your board uses I/O registers
+ to control them, it is probably better to let NAND_CTL_SETCLE()
+ and company do it.
+
+ #define WRITE_NAND_ADDRESS(d, adr)
+ Write the address byte `d' to the flash at `adr' with the
+ ALE (address latch enable) line true. If your board uses writes to
+ different addresses to control CLE and ALE, you can modify `adr'
+ to be the appropriate address here. If your board uses I/O registers
+ to control them, it is probably better to let NAND_CTL_SETALE()
+ and company do it.
+
+ #define WRITE_NAND(d, adr)
+ Write the data byte `d' to the flash at `adr' with the
+ ALE and CLE lines false. If your board uses writes to
+ different addresses to control CLE and ALE, you can modify `adr'
+ to be the appropriate address here. If your board uses I/O registers
+ to control them, it is probably better to let NAND_CTL_CLRALE()
+ and company do it.
+
+ #define READ_NAND(adr)
+ Read a data byte from the flash at `adr' with the
+ ALE and CLE lines false. If your board uses reads from
+ different addresses to control CLE and ALE, you can modify `adr'
+ to be the appropriate address here. If your board uses I/O registers
+ to control them, it is probably better to let NAND_CTL_CLRALE()
+ and company do it.
+
+ #define NAND_DISABLE_CE(nand)
+ Set CE (Chip Enable) low to enable the NAND flash.
+
+ #define NAND_ENABLE_CE(nand)
+ Set CE (Chip Enable) high to disable the NAND flash.
+
+ #define NAND_CTL_CLRALE(nandptr)
+ Set ALE (address latch enable) low. If ALE control is handled by
+ WRITE_NAND_ADDRESS() this can be empty.
+
+ #define NAND_CTL_SETALE(nandptr)
+ Set ALE (address latch enable) high. If ALE control is handled by
+ WRITE_NAND_ADDRESS() this can be empty.
+
+ #define NAND_CTL_CLRCLE(nandptr)
+ Set CLE (command latch enable) low. If CLE control is handled by
+ WRITE_NAND_ADDRESS() this can be empty.
+
+ #define NAND_CTL_SETCLE(nandptr)
+ Set CLE (command latch enable) high. If CLE control is handled by
+ WRITE_NAND_ADDRESS() this can be empty.
+
+More Definitions:
+
+ These definitions are needed in the board configuration for now, but
+ may really belong in a header file.
+ TODO: Figure which ones are truly configuration settings and rename
+ them to CFG_NAND_... and move the rest somewhere appropriate.
+
+ #define SECTORSIZE 512
+ #define ADDR_COLUMN 1
+ #define ADDR_PAGE 2
+ #define ADDR_COLUMN_PAGE 3
+ #define NAND_ChipID_UNKNOWN 0x00
+ #define NAND_MAX_FLOORS 1
+ #define NAND_MAX_CHIPS 1
+