1NAND FLASH commands and notes 2 3See NOTE below!!! 4 5# (C) Copyright 2003 6# Dave Ellis, SIXNET, dge@sixnetio.com 7# 8# SPDX-License-Identifier: GPL-2.0+ 9 10Commands: 11 12 nand bad 13 Print a list of all of the bad blocks in the current device. 14 15 nand device 16 Print information about the current NAND device. 17 18 nand device num 19 Make device `num' the current device and print information about it. 20 21 nand erase off|partition size 22 nand erase clean [off|partition size] 23 Erase `size' bytes starting at offset `off'. Alternatively partition 24 name can be specified, in this case size will be eventually limited 25 to not exceed partition size (this behaviour applies also to read 26 and write commands). Only complete erase blocks can be erased. 27 28 If `erase' is specified without an offset or size, the entire flash 29 is erased. If `erase' is specified with partition but without an 30 size, the entire partition is erased. 31 32 If `clean' is specified, a JFFS2-style clean marker is written to 33 each block after it is erased. 34 35 This command will not erase blocks that are marked bad. There is 36 a debug option in cmd_nand.c to allow bad blocks to be erased. 37 Please read the warning there before using it, as blocks marked 38 bad by the manufacturer must _NEVER_ be erased. 39 40 nand info 41 Print information about all of the NAND devices found. 42 43 nand read addr ofs|partition size 44 Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that 45 are marked bad are skipped. If a page cannot be read because an 46 uncorrectable data error is found, the command stops with an error. 47 48 nand read.oob addr ofs|partition size 49 Read `size' bytes from the out-of-band data area corresponding to 50 `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of 51 data for one 512-byte page or 2 256-byte pages. There is no check 52 for bad blocks or ECC errors. 53 54 nand write addr ofs|partition size 55 Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that 56 are marked bad are skipped. If a page cannot be read because an 57 uncorrectable data error is found, the command stops with an error. 58 59 As JFFS2 skips blocks similarly, this allows writing a JFFS2 image, 60 as long as the image is short enough to fit even after skipping the 61 bad blocks. Compact images, such as those produced by mkfs.jffs2 62 should work well, but loading an image copied from another flash is 63 going to be trouble if there are any bad blocks. 64 65 nand write.trimffs addr ofs|partition size 66 Enabled by the CONFIG_CMD_NAND_TRIMFFS macro. This command will write to 67 the NAND flash in a manner identical to the 'nand write' command 68 described above -- with the additional check that all pages at the end 69 of eraseblocks which contain only 0xff data will not be written to the 70 NAND flash. This behaviour is required when flashing UBI images 71 containing UBIFS volumes as per the UBI FAQ[1]. 72 73 [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo 74 75 nand write.oob addr ofs|partition size 76 Write `size' bytes from `addr' to the out-of-band data area 77 corresponding to `ofs' in NAND flash. This is limited to the 16 bytes 78 of data for one 512-byte page or 2 256-byte pages. There is no check 79 for bad blocks. 80 81 nand read.raw addr ofs|partition [count] 82 nand write.raw addr ofs|partition [count] 83 Read or write one or more pages at "ofs" in NAND flash, from or to 84 "addr" in memory. This is a raw access, so ECC is avoided and the 85 OOB area is transferred as well. If count is absent, it is assumed 86 to be one page. As with .yaffs2 accesses, the data is formatted as 87 a packed sequence of "data, oob, data, oob, ..." -- no alignment of 88 individual pages is maintained. 89 90Configuration Options: 91 92 CONFIG_CMD_NAND 93 Enables NAND support and commmands. 94 95 CONFIG_CMD_NAND_TORTURE 96 Enables the torture command (see description of this command below). 97 98 CONFIG_MTD_NAND_ECC_JFFS2 99 Define this if you want the Error Correction Code information in 100 the out-of-band data to be formatted to match the JFFS2 file system. 101 CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for 102 someone to implement. 103 104 CONFIG_SYS_MAX_NAND_DEVICE 105 The maximum number of NAND devices you want to support. 106 107 CONFIG_SYS_NAND_MAX_CHIPS 108 The maximum number of NAND chips per device to be supported. 109 110 CONFIG_SYS_NAND_SELF_INIT 111 Traditionally, glue code in drivers/mtd/nand/nand.c has driven 112 the initialization process -- it provides the mtd and nand 113 structs, calls a board init function for a specific device, 114 calls nand_scan(), and registers with mtd. 115 116 This arrangement does not provide drivers with the flexibility to 117 run code between nand_scan_ident() and nand_scan_tail(), or other 118 deviations from the "normal" flow. 119 120 If a board defines CONFIG_SYS_NAND_SELF_INIT, drivers/mtd/nand/nand.c 121 will make one call to board_nand_init(), with no arguments. That 122 function is responsible for calling a driver init function for 123 each NAND device on the board, that performs all initialization 124 tasks except setting mtd->name, and registering with the rest of 125 U-Boot. Those last tasks are accomplished by calling nand_register() 126 on the new mtd device. 127 128 Example of new init to be added to the end of an existing driver 129 init: 130 131 /* 132 * devnum is the device number to be used in nand commands 133 * and in mtd->name. Must be less than 134 * CONFIG_SYS_NAND_MAX_DEVICE. 135 */ 136 mtd = &nand_info[devnum]; 137 138 /* chip is struct nand_chip, and is now provided by the driver. */ 139 mtd->priv = &chip; 140 141 /* 142 * Fill in appropriate values if this driver uses these fields, 143 * or uses the standard read_byte/write_buf/etc. functions from 144 * nand_base.c that use these fields. 145 */ 146 chip.IO_ADDR_R = ...; 147 chip.IO_ADDR_W = ...; 148 149 if (nand_scan_ident(mtd, CONFIG_SYS_MAX_NAND_CHIPS, NULL)) 150 error out 151 152 /* 153 * Insert here any code you wish to run after the chip has been 154 * identified, but before any other I/O is done. 155 */ 156 157 if (nand_scan_tail(mtd)) 158 error out 159 160 if (nand_register(devnum)) 161 error out 162 163 In addition to providing more flexibility to the driver, it reduces 164 the difference between a U-Boot driver and its Linux counterpart. 165 nand_init() is now reduced to calling board_nand_init() once, and 166 printing a size summary. This should also make it easier to 167 transition to delayed NAND initialization. 168 169 Please convert your driver even if you don't need the extra 170 flexibility, so that one day we can eliminate the old mechanism. 171 172NOTE: 173===== 174 175The current NAND implementation is based on what is in recent 176Linux kernels. The old legacy implementation has been removed. 177 178If you have board code which used CONFIG_NAND_LEGACY, you'll need 179to convert to the current NAND interface for it to continue to work. 180 181The Disk On Chip driver is currently broken and has been for some time. 182There is a driver in drivers/mtd/nand, taken from Linux, that works with 183the current NAND system but has not yet been adapted to the u-boot 184environment. 185 186Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006 187 188JFFS2 related commands: 189 190 implement "nand erase clean" and old "nand erase" 191 using both the new code which is able to skip bad blocks 192 "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob. 193 194Miscellaneous and testing commands: 195 "markbad [offset]" 196 create an artificial bad block (for testing bad block handling) 197 198 "scrub [offset length]" 199 like "erase" but don't skip bad block. Instead erase them. 200 DANGEROUS!!! Factory set bad blocks will be lost. Use only 201 to remove artificial bad blocks created with the "markbad" command. 202 203 "torture offset" 204 Torture block to determine if it is still reliable. 205 Enabled by the CONFIG_CMD_NAND_TORTURE configuration option. 206 This command returns 0 if the block is still reliable, else 1. 207 If the block is detected as unreliable, it is up to the user to decide to 208 mark this block as bad. 209 The analyzed block is put through 3 erase / write cycles (or less if the block 210 is detected as unreliable earlier). 211 This command can be used in scripts, e.g. together with the markbad command to 212 automate retries and handling of possibly newly detected bad blocks if the 213 nand write command fails. 214 It can also be used manually by users having seen some NAND errors in logs to 215 search the root cause of these errors. 216 The underlying nand_torture() function is also useful for code willing to 217 automate actions following a nand->write() error. This would e.g. be required 218 in order to program or update safely firmware to NAND, especially for the UBI 219 part of such firmware. 220 221 222NAND locking command (for chips with active LOCKPRE pin) 223 224 "nand lock" 225 set NAND chip to lock state (all pages locked) 226 227 "nand lock tight" 228 set NAND chip to lock tight state (software can't change locking anymore) 229 230 "nand lock status" 231 displays current locking status of all pages 232 233 "nand unlock [offset] [size]" 234 unlock consecutive area (can be called multiple times for different areas) 235 236 "nand unlock.allexcept [offset] [size]" 237 unlock all except specified consecutive area 238 239I have tested the code with board containing 128MiB NAND large page chips 240and 32MiB small page chips. 241