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'.  Blocks that
  61       are marked bad are skipped.  If a page cannot be read because an
  62       uncorrectable data error is found, the command stops with an error.
  63
  64    nand read.oob addr ofs|partition size
  65       Read `size' bytes from the out-of-band data area corresponding to
  66       `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
  67       data for one 512-byte page or 2 256-byte pages. There is no check
  68       for bad blocks or ECC errors.
  69
  70    nand write addr ofs|partition size
  71       Write `size' bytes from `addr' to `ofs' in NAND flash.  Blocks that
  72       are marked bad are skipped.  If a page cannot be read because an
  73       uncorrectable data error is found, the command stops with an error.
  74
  75       As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
  76       as long as the image is short enough to fit even after skipping the
  77       bad blocks.  Compact images, such as those produced by mkfs.jffs2
  78       should work well, but loading an image copied from another flash is
  79       going to be trouble if there are any bad blocks.
  80
  81    nand write.oob addr ofs|partition size
  82       Write `size' bytes from `addr' to the out-of-band data area
  83       corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
  84       of data for one 512-byte page or 2 256-byte pages. There is no check
  85       for bad blocks.
  86
  87 Configuration Options:
  88
  89    CONFIG_CMD_NAND
  90       Enables NAND support and commmands.
  91
  92    CONFIG_MTD_NAND_ECC_JFFS2
  93       Define this if you want the Error Correction Code information in
  94       the out-of-band data to be formatted to match the JFFS2 file system.
  95       CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for
  96       someone to implement.
  97
  98    CONFIG_SYS_MAX_NAND_DEVICE
  99       The maximum number of NAND devices you want to support.
 100
 101 NAND Interface:
 102
 103    #define NAND_WAIT_READY(nand)
 104       Wait until the NAND flash is ready. Typically this would be a
 105       loop waiting for the READY/BUSY line from the flash to indicate it
 106       it is ready.
 107
 108    #define WRITE_NAND_COMMAND(d, adr)
 109       Write the command byte `d' to the flash at `adr' with the
 110       CLE (command latch enable) line true. If your board uses writes to
 111       different addresses to control CLE and ALE, you can modify `adr'
 112       to be the appropriate address here. If your board uses I/O registers
 113       to control them, it is probably better to let NAND_CTL_SETCLE()
 114       and company do it.
 115
 116    #define WRITE_NAND_ADDRESS(d, adr)
 117       Write the address byte `d' to the flash at `adr' with the
 118       ALE (address latch enable) line true. If your board uses writes to
 119       different addresses to control CLE and ALE, you can modify `adr'
 120       to be the appropriate address here. If your board uses I/O registers
 121       to control them, it is probably better to let NAND_CTL_SETALE()
 122       and company do it.
 123
 124    #define WRITE_NAND(d, adr)
 125       Write the data byte `d' to the flash at `adr' with the
 126       ALE and CLE lines false. If your board uses writes to
 127       different addresses to control CLE and ALE, you can modify `adr'
 128       to be the appropriate address here. If your board uses I/O registers
 129       to control them, it is probably better to let NAND_CTL_CLRALE()
 130       and company do it.
 131
 132    #define READ_NAND(adr)
 133       Read a data byte from the flash at `adr' with the
 134       ALE and CLE lines false. If your board uses reads from
 135       different addresses to control CLE and ALE, you can modify `adr'
 136       to be the appropriate address here. If your board uses I/O registers
 137       to control them, it is probably better to let NAND_CTL_CLRALE()
 138       and company do it.
 139
 140    #define NAND_DISABLE_CE(nand)
 141       Set CE (Chip Enable) low to enable the NAND flash.
 142
 143    #define NAND_ENABLE_CE(nand)
 144       Set CE (Chip Enable) high to disable the NAND flash.
 145
 146    #define NAND_CTL_CLRALE(nandptr)
 147       Set ALE (address latch enable) low. If ALE control is handled by
 148       WRITE_NAND_ADDRESS() this can be empty.
 149
 150    #define NAND_CTL_SETALE(nandptr)
 151       Set ALE (address latch enable) high. If ALE control is handled by
 152       WRITE_NAND_ADDRESS() this can be empty.
 153
 154    #define NAND_CTL_CLRCLE(nandptr)
 155       Set CLE (command latch enable) low. If CLE control is handled by
 156       WRITE_NAND_ADDRESS() this can be empty.
 157
 158    #define NAND_CTL_SETCLE(nandptr)
 159       Set CLE (command latch enable) high. If CLE control is handled by
 160       WRITE_NAND_ADDRESS() this can be empty.
 161
 162 More Definitions:
 163
 164    These definitions are needed in the board configuration for now, but
 165    may really belong in a header file.
 166    TODO: Figure which ones are truly configuration settings and rename
 167          them to CONFIG_SYS_NAND_... and move the rest somewhere appropriate.
 168
 169    #define SECTORSIZE 512
 170    #define ADDR_COLUMN 1
 171    #define ADDR_PAGE 2
 172    #define ADDR_COLUMN_PAGE 3
 173    #define NAND_ChipID_UNKNOWN 0x00
 174    #define NAND_MAX_FLOORS 1
 175    #define CONFIG_SYS_NAND_MAX_CHIPS 1
 176
 177    #define CONFIG_SYS_DAVINCI_BROKEN_ECC
 178       Versions of U-Boot <= 1.3.3 and Montavista Linux kernels
 179       generated bogus ECCs on large-page NAND. Both large and small page
 180       NAND ECCs were incompatible with the Linux davinci git tree (since
 181       NAND was integrated in 2.6.24).
 182       Turn this ON if you want backwards compatibility.
 183       Turn this OFF if you want U-Boot and the Linux davinci git kernel
 184       to use the same ECC format.
 185
 186 NOTE:
 187 =====
 188
 189 We now use a complete rewrite of the NAND code based on what is in
 190 2.6.12 Linux kernel.
 191
 192 The old NAND handling code has been re-factored and is now confined
 193 to only board-specific files and - unfortunately - to the DoC code
 194 (see below). A new configuration variable has been introduced:
 195 CONFIG_NAND_LEGACY, which has to be defined in the board config file if
 196 that board uses legacy code.
 197
 198 The necessary changes have been made to all affected boards, and no
 199 build breakage has been introduced, except for NETTA and NETTA_ISDN
 200 targets from MAKEALL. This is due to the fact that these two boards
 201 use JFFS, which has been adopted to use the new NAND, and at the same
 202 time use NAND in legacy mode. The breakage will disappear when the
 203 board-specific code is changed to the new NAND.
 204
 205 As mentioned above, the legacy code is still used by the DoC subsystem.
 206 The consequence of this is that the legacy NAND can't be removed  from
 207 the tree until the DoC is ported to use the new NAND support (or boards
 208 with DoC will break).
 209
 210
 211 Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006
 212
 213 JFFS2 related commands:
 214
 215   implement "nand erase clean" and old "nand erase"
 216   using both the new code which is able to skip bad blocks
 217   "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
 218
 219 Miscellaneous and testing commands:
 220   "markbad [offset]"
 221   create an artificial bad block (for testing bad block handling)
 222
 223   "scrub [offset length]"
 224   like "erase" but don't skip bad block. Instead erase them.
 225   DANGEROUS!!! Factory set bad blocks will be lost. Use only
 226   to remove artificial bad blocks created with the "markbad" command.
 227
 228
 229 NAND locking command (for chips with active LOCKPRE pin)
 230
 231   "nand lock"
 232   set NAND chip to lock state (all pages locked)
 233
 234   "nand lock tight"
 235   set NAND chip to lock tight state (software can't change locking anymore)
 236
 237   "nand lock status"
 238   displays current locking status of all pages
 239
 240   "nand unlock [offset] [size]"
 241   unlock consecutive area (can be called multiple times for different areas)
 242
 243
 244 I have tested the code with board containing 128MiB NAND large page chips
 245 and 32MiB small page chips.