1 NAND FLASH commands and notes
6 # Dave Ellis, SIXNET, dge@sixnetio.com
8 # See file CREDITS for list of people who contributed to this
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29 Print a list of all of the bad blocks in the current device.
32 Print information about the current NAND device.
35 Make device `num' the current device and print information about it.
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.
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.
48 If `clean' is specified, a JFFS2-style clean marker is written to
49 each block after it is erased.
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.
57 Print information about all of the NAND devices found.
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.
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.
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.
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.
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
87 Configuration Options:
90 Enables NAND support and commmands.
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
98 CONFIG_SYS_MAX_NAND_DEVICE
99 The maximum number of NAND devices you want to support.
101 CONFIG_SYS_NAND_MAX_CHIPS
102 The maximum number of NAND chips per device to be supported.
107 The current NAND implementation is based on what is in recent
108 Linux kernels. The old legacy implementation has been removed.
110 If you have board code which used CONFIG_NAND_LEGACY, you'll need
111 to convert to the current NAND interface for it to continue to work.
113 The Disk On Chip driver is currently broken and has been for some time.
114 There is a driver in drivers/mtd/nand, taken from Linux, that works with
115 the current NAND system but has not yet been adapted to the u-boot
118 Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006
120 JFFS2 related commands:
122 implement "nand erase clean" and old "nand erase"
123 using both the new code which is able to skip bad blocks
124 "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
126 Miscellaneous and testing commands:
128 create an artificial bad block (for testing bad block handling)
130 "scrub [offset length]"
131 like "erase" but don't skip bad block. Instead erase them.
132 DANGEROUS!!! Factory set bad blocks will be lost. Use only
133 to remove artificial bad blocks created with the "markbad" command.
136 NAND locking command (for chips with active LOCKPRE pin)
139 set NAND chip to lock state (all pages locked)
142 set NAND chip to lock tight state (software can't change locking anymore)
145 displays current locking status of all pages
147 "nand unlock [offset] [size]"
148 unlock consecutive area (can be called multiple times for different areas)
151 I have tested the code with board containing 128MiB NAND large page chips
152 and 32MiB small page chips.