doc/README.nand

   1 NAND FLASH commands and notes
   2
   3 See NOTE below!!!
   4
   5 # (C) Copyright 2003
   6 # Dave Ellis, SIXNET, dge@sixnetio.com
   7 #
   8 # See file CREDITS for list of people who contributed to this
   9 # project.
  10 #
  11 # This program is free software; you can redistribute it and/or
  12 # modify it under the terms of the GNU General Public License as
  13 # published by the Free Software Foundation; either version 2 of
  14 # the License, or (at your option) any later version.
  15 #
  16 # This program is distributed in the hope that it will be useful,
  17 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 # GNU General Public License for more details.
  20 #
  21 # You should have received a copy of the GNU General Public License
  22 # along with this program; if not, write to the Free Software
  23 # Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  24 # MA 02111-1307 USA
  25
  26 Commands:
  27
  28    nand bad
  29       Print a list of all of the bad blocks in the current device.
  30
  31    nand device
  32       Print information about the current NAND device.
  33
  34    nand device num
  35       Make device `num' the current device and print information about it.
  36
  37    nand erase off|partition size
  38    nand erase clean [off|partition size]
  39       Erase `size' bytes starting at offset `off'. Alternatively partition
  40       name can be specified, in this case size will be eventually limited
  41       to not exceed partition size (this behaviour applies also to read
  42       and write commands). Only complete erase blocks can be erased.
  43
  44       If `erase' is specified without an offset or size, the entire flash
  45       is erased. If `erase' is specified with partition but without an
  46       size, the entire partition is erased.
  47
  48       If `clean' is specified, a JFFS2-style clean marker is written to
  49       each block after it is erased.
  50
  51       This command will not erase blocks that are marked bad. There is
  52       a debug option in cmd_nand.c to allow bad blocks to be erased.
  53       Please read the warning there before using it, as blocks marked
  54       bad by the manufacturer must _NEVER_ be erased.
  55
  56    nand info
  57       Print information about all of the NAND devices found.
  58
  59    nand read addr ofs|partition size
  60       Read `size' bytes from `ofs' in NAND flash to `addr'. If a page
  61       cannot be read because it is marked bad or an uncorrectable data
  62       error is found the command stops with an error.
  63
  64    nand read.jffs2 addr ofs|partition size
  65       Like `read', but the data for blocks that are marked bad is read as
  66       0xff. This gives a readable JFFS2 image that can be processed by
  67       the JFFS2 commands such as ls and fsload.
  68
  69    nand read.oob addr ofs|partition size
  70       Read `size' bytes from the out-of-band data area corresponding to
  71       `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
  72       data for one 512-byte page or 2 256-byte pages. There is no check
  73       for bad blocks or ECC errors.
  74
  75    nand write addr ofs|partition size
  76       Write `size' bytes from `addr' to `ofs' in NAND flash. If a page
  77       cannot be written because it is marked bad or the write fails the
  78       command stops with an error.
  79
  80    nand write.jffs2 addr ofs|partition size
  81       Like `write', but blocks that are marked bad are skipped and the
  82       is written to the next block instead. This allows writing writing
  83       a JFFS2 image, as long as the image is short enough to fit even
  84       after skipping the bad blocks. Compact images, such as those
  85       produced by mkfs.jffs2 should work well, but loading an image copied
  86       from another flash is going to be trouble if there are any bad blocks.
  87
  88    nand write.oob addr ofs|partition size
  89       Write `size' bytes from `addr' to the out-of-band data area
  90       corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
  91       of data for one 512-byte page or 2 256-byte pages. There is no check
  92       for bad blocks.
  93
  94 Configuration Options:
  95
  96    CONFIG_CMD_NAND
  97       Enables NAND support and commmands.
  98
  99    CONFIG_MTD_NAND_ECC_JFFS2
 100       Define this if you want the Error Correction Code information in
 101       the out-of-band data to be formatted to match the JFFS2 file system.
 102       CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
 103       someone to implement.
 104
 105    CFG_MAX_NAND_DEVICE
 106       The maximum number of NAND devices you want to support.
 107
 108 NAND Interface:
 109
 110    #define NAND_WAIT_READY(nand)
 111       Wait until the NAND flash is ready. Typically this would be a
 112       loop waiting for the READY/BUSY line from the flash to indicate it
 113       it is ready.
 114
 115    #define WRITE_NAND_COMMAND(d, adr)
 116       Write the command byte `d' to the flash at `adr' with the
 117       CLE (command latch enable) line true. If your board uses writes to
 118       different addresses to control CLE and ALE, you can modify `adr'
 119       to be the appropriate address here. If your board uses I/O registers
 120       to control them, it is probably better to let NAND_CTL_SETCLE()
 121       and company do it.
 122
 123    #define WRITE_NAND_ADDRESS(d, adr)
 124       Write the address byte `d' to the flash at `adr' with the
 125       ALE (address latch enable) line true. If your board uses writes to
 126       different addresses to control CLE and ALE, you can modify `adr'
 127       to be the appropriate address here. If your board uses I/O registers
 128       to control them, it is probably better to let NAND_CTL_SETALE()
 129       and company do it.
 130
 131    #define WRITE_NAND(d, adr)
 132       Write the data byte `d' to the flash at `adr' with the
 133       ALE and CLE lines false. If your board uses writes to
 134       different addresses to control CLE and ALE, you can modify `adr'
 135       to be the appropriate address here. If your board uses I/O registers
 136       to control them, it is probably better to let NAND_CTL_CLRALE()
 137       and company do it.
 138
 139    #define READ_NAND(adr)
 140       Read a data byte from the flash at `adr' with the
 141       ALE and CLE lines false. If your board uses reads from
 142       different addresses to control CLE and ALE, you can modify `adr'
 143       to be the appropriate address here. If your board uses I/O registers
 144       to control them, it is probably better to let NAND_CTL_CLRALE()
 145       and company do it.
 146
 147    #define NAND_DISABLE_CE(nand)
 148       Set CE (Chip Enable) low to enable the NAND flash.
 149
 150    #define NAND_ENABLE_CE(nand)
 151       Set CE (Chip Enable) high to disable the NAND flash.
 152
 153    #define NAND_CTL_CLRALE(nandptr)
 154       Set ALE (address latch enable) low. If ALE control is handled by
 155       WRITE_NAND_ADDRESS() this can be empty.
 156
 157    #define NAND_CTL_SETALE(nandptr)
 158       Set ALE (address latch enable) high. If ALE control is handled by
 159       WRITE_NAND_ADDRESS() this can be empty.
 160
 161    #define NAND_CTL_CLRCLE(nandptr)
 162       Set CLE (command latch enable) low. If CLE control is handled by
 163       WRITE_NAND_ADDRESS() this can be empty.
 164
 165    #define NAND_CTL_SETCLE(nandptr)
 166       Set CLE (command latch enable) high. If CLE control is handled by
 167       WRITE_NAND_ADDRESS() this can be empty.
 168
 169 More Definitions:
 170
 171    These definitions are needed in the board configuration for now, but
 172    may really belong in a header file.
 173    TODO: Figure which ones are truly configuration settings and rename
 174          them to CFG_NAND_... and move the rest somewhere appropriate.
 175
 176    #define SECTORSIZE 512
 177    #define ADDR_COLUMN 1
 178    #define ADDR_PAGE 2
 179    #define ADDR_COLUMN_PAGE 3
 180    #define NAND_ChipID_UNKNOWN 0x00
 181    #define NAND_MAX_FLOORS 1
 182    #define NAND_MAX_CHIPS 1
 183
 184
 185 NOTE:
 186 =====
 187
 188 We now use a complete rewrite of the NAND code based on what is in
 189 2.6.12 Linux kernel.
 190
 191 The old NAND handling code has been re-factored and is now confined
 192 to only board-specific files and - unfortunately - to the DoC code
 193 (see below). A new configuration variable has been introduced:
 194 CFG_NAND_LEGACY, which has to be defined in the board config file if
 195 that board uses legacy code.
 196
 197 The necessary changes have been made to all affected boards, and no
 198 build breakage has been introduced, except for NETTA and NETTA_ISDN
 199 targets from MAKEALL. This is due to the fact that these two boards
 200 use JFFS, which has been adopted to use the new NAND, and at the same
 201 time use NAND in legacy mode. The breakage will disappear when the
 202 board-specific code is changed to the new NAND.
 203
 204 As mentioned above, the legacy code is still used by the DoC subsystem.
 205 The consequence of this is that the legacy NAND can't be removed  from
 206 the tree until the DoC is ported to use the new NAND support (or boards
 207 with DoC will break).
 208
 209
 210 Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006
 211
 212 JFFS2 related commands:
 213
 214   implement "nand erase clean" and old "nand erase"
 215   using both the new code which is able to skip bad blocks
 216   "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
 217
 218   "nand write.jffs2"
 219   like "nand write" but skip found bad eraseblocks
 220
 221   "nand read.jffs2"
 222   like "nand read" but skip found bad eraseblocks
 223
 224 Miscellaneous and testing commands:
 225   "markbad [offset]"
 226   create an artificial bad block (for testing bad block handling)
 227
 228   "scrub [offset length]"
 229   like "erase" but don't skip bad block. Instead erase them.
 230   DANGEROUS!!! Factory set bad blocks will be lost. Use only
 231   to remove artificial bad blocks created with the "markbad" command.
 232
 233
 234 NAND locking command (for chips with active LOCKPRE pin)
 235
 236   "nand lock"
 237   set NAND chip to lock state (all pages locked)
 238
 239   "nand lock tight"
 240   set NAND chip to lock tight state (software can't change locking anymore)
 241
 242   "nand lock status"
 243   displays current locking status of all pages
 244
 245   "nand unlock [offset] [size]"
 246   unlock consecutive area (can be called multiple times for different areas)
 247
 248
 249 I have tested the code with board containing 128MiB NAND large page chips
 250 and 32MiB small page chips.