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_SYS_NAND_U_BOOT_OFFS 93 NAND Offset from where SPL will read u-boot image. This is the starting 94 address of u-boot MTD partition in NAND. 95 96 CONFIG_CMD_NAND 97 Enables NAND support and commands. 98 99 CONFIG_CMD_NAND_TORTURE 100 Enables the torture command (see description of this command below). 101 102 CONFIG_SYS_MAX_NAND_DEVICE 103 The maximum number of NAND devices you want to support. 104 105 CONFIG_SYS_NAND_MAX_ECCPOS 106 If specified, overrides the maximum number of ECC bytes 107 supported. Useful for reducing image size, especially with SPL. 108 This must be at least 48 if nand_base.c is used. 109 110 CONFIG_SYS_NAND_MAX_OOBFREE 111 If specified, overrides the maximum number of free OOB regions 112 supported. Useful for reducing image size, especially with SPL. 113 This must be at least 2 if nand_base.c is used. 114 115 CONFIG_SYS_NAND_MAX_CHIPS 116 The maximum number of NAND chips per device to be supported. 117 118 CONFIG_SYS_NAND_SELF_INIT 119 Traditionally, glue code in drivers/mtd/nand/nand.c has driven 120 the initialization process -- it provides the mtd and nand 121 structs, calls a board init function for a specific device, 122 calls nand_scan(), and registers with mtd. 123 124 This arrangement does not provide drivers with the flexibility to 125 run code between nand_scan_ident() and nand_scan_tail(), or other 126 deviations from the "normal" flow. 127 128 If a board defines CONFIG_SYS_NAND_SELF_INIT, drivers/mtd/nand/nand.c 129 will make one call to board_nand_init(), with no arguments. That 130 function is responsible for calling a driver init function for 131 each NAND device on the board, that performs all initialization 132 tasks except setting mtd->name, and registering with the rest of 133 U-Boot. Those last tasks are accomplished by calling nand_register() 134 on the new mtd device. 135 136 Example of new init to be added to the end of an existing driver 137 init: 138 139 /* chip is struct nand_chip, and is now provided by the driver. */ 140 mtd = &chip.mtd; 141 142 /* 143 * Fill in appropriate values if this driver uses these fields, 144 * or uses the standard read_byte/write_buf/etc. functions from 145 * nand_base.c that use these fields. 146 */ 147 chip.IO_ADDR_R = ...; 148 chip.IO_ADDR_W = ...; 149 150 if (nand_scan_ident(mtd, CONFIG_SYS_MAX_NAND_CHIPS, NULL)) 151 error out 152 153 /* 154 * Insert here any code you wish to run after the chip has been 155 * identified, but before any other I/O is done. 156 */ 157 158 if (nand_scan_tail(mtd)) 159 error out 160 161 /* 162 * devnum is the device number to be used in nand commands 163 * and in mtd->name. Must be less than CONFIG_SYS_NAND_MAX_DEVICE. 164 */ 165 if (nand_register(devnum, mtd)) 166 error out 167 168 In addition to providing more flexibility to the driver, it reduces 169 the difference between a U-Boot driver and its Linux counterpart. 170 nand_init() is now reduced to calling board_nand_init() once, and 171 printing a size summary. This should also make it easier to 172 transition to delayed NAND initialization. 173 174 Please convert your driver even if you don't need the extra 175 flexibility, so that one day we can eliminate the old mechanism. 176 177 178 CONFIG_SYS_NAND_ONFI_DETECTION 179 Enables detection of ONFI compliant devices during probe. 180 And fetching device parameters flashed on device, by parsing 181 ONFI parameter page. 182 183 CONFIG_BCH 184 Enables software based BCH ECC algorithm present in lib/bch.c 185 This is used by SoC platforms which do not have built-in ELM 186 hardware engine required for BCH ECC correction. 187 188 189Platform specific options 190========================= 191 CONFIG_NAND_OMAP_GPMC 192 Enables omap_gpmc.c driver for OMAPx and AMxxxx platforms. 193 GPMC controller is used for parallel NAND flash devices, and can 194 do ECC calculation (not ECC error detection) for HAM1, BCH4, BCH8 195 and BCH16 ECC algorithms. 196 197 CONFIG_NAND_OMAP_ELM 198 Enables omap_elm.c driver for OMAPx and AMxxxx platforms. 199 ELM controller is used for ECC error detection (not ECC calculation) 200 of BCH4, BCH8 and BCH16 ECC algorithms. 201 Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine, 202 thus such SoC platforms need to depend on software library for ECC error 203 detection. However ECC calculation on such plaforms would still be 204 done by GPMC controller. 205 206 CONFIG_SPL_NAND_AM33XX_BCH 207 Enables SPL-NAND driver (am335x_spl_bch.c) which supports ELM based 208 hardware ECC correction. This is useful for platforms which have ELM 209 hardware engine and use NAND boot mode. 210 Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine, 211 so those platforms should use CONFIG_SPL_NAND_SIMPLE for enabling 212 SPL-NAND driver with software ECC correction support. 213 214 CONFIG_NAND_OMAP_ECCSCHEME 215 On OMAP platforms, this CONFIG specifies NAND ECC scheme. 216 It can take following values: 217 OMAP_ECC_HAM1_CODE_SW 218 1-bit Hamming code using software lib. 219 (for legacy devices only) 220 OMAP_ECC_HAM1_CODE_HW 221 1-bit Hamming code using GPMC hardware. 222 (for legacy devices only) 223 OMAP_ECC_BCH4_CODE_HW_DETECTION_SW 224 4-bit BCH code (unsupported) 225 OMAP_ECC_BCH4_CODE_HW 226 4-bit BCH code (unsupported) 227 OMAP_ECC_BCH8_CODE_HW_DETECTION_SW 228 8-bit BCH code with 229 - ecc calculation using GPMC hardware engine, 230 - error detection using software library. 231 - requires CONFIG_BCH to enable software BCH library 232 (For legacy device which do not have ELM h/w engine) 233 OMAP_ECC_BCH8_CODE_HW 234 8-bit BCH code with 235 - ecc calculation using GPMC hardware engine, 236 - error detection using ELM hardware engine. 237 OMAP_ECC_BCH16_CODE_HW 238 16-bit BCH code with 239 - ecc calculation using GPMC hardware engine, 240 - error detection using ELM hardware engine. 241 242 How to select ECC scheme on OMAP and AMxx platforms ? 243 ----------------------------------------------------- 244 Though higher ECC schemes have more capability to detect and correct 245 bit-flips, but still selection of ECC scheme is dependent on following 246 - hardware engines present in SoC. 247 Some legacy OMAP SoC do not have ELM h/w engine thus such 248 SoC cannot support BCHx_HW ECC schemes. 249 - size of OOB/Spare region 250 With higher ECC schemes, more OOB/Spare area is required to 251 store ECC. So choice of ECC scheme is limited by NAND oobsize. 252 253 In general following expression can help: 254 NAND_OOBSIZE >= 2 + (NAND_PAGESIZE / 512) * ECC_BYTES 255 where 256 NAND_OOBSIZE = number of bytes available in 257 OOB/spare area per NAND page. 258 NAND_PAGESIZE = bytes in main-area of NAND page. 259 ECC_BYTES = number of ECC bytes generated to 260 protect 512 bytes of data, which is: 261 3 for HAM1_xx ecc schemes 262 7 for BCH4_xx ecc schemes 263 14 for BCH8_xx ecc schemes 264 26 for BCH16_xx ecc schemes 265 266 example to check for BCH16 on 2K page NAND 267 NAND_PAGESIZE = 2048 268 NAND_OOBSIZE = 64 269 2 + (2048 / 512) * 26 = 106 > NAND_OOBSIZE 270 Thus BCH16 cannot be supported on 2K page NAND. 271 272 However, for 4K pagesize NAND 273 NAND_PAGESIZE = 4096 274 NAND_OOBSIZE = 64 275 ECC_BYTES = 26 276 2 + (4096 / 512) * 26 = 210 < NAND_OOBSIZE 277 Thus BCH16 can be supported on 4K page NAND. 278 279 280 CONFIG_NAND_OMAP_GPMC_PREFETCH 281 On OMAP platforms that use the GPMC controller 282 (CONFIG_NAND_OMAP_GPMC_PREFETCH), this options enables the code that 283 uses the prefetch mode to speed up read operations. 284 285NOTE: 286===== 287 288The Disk On Chip driver is currently broken and has been for some time. 289There is a driver in drivers/mtd/nand, taken from Linux, that works with 290the current NAND system but has not yet been adapted to the u-boot 291environment. 292 293Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006 294 295JFFS2 related commands: 296 297 implement "nand erase clean" and old "nand erase" 298 using both the new code which is able to skip bad blocks 299 "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob. 300 301Miscellaneous and testing commands: 302 "markbad [offset]" 303 create an artificial bad block (for testing bad block handling) 304 305 "scrub [offset length]" 306 like "erase" but don't skip bad block. Instead erase them. 307 DANGEROUS!!! Factory set bad blocks will be lost. Use only 308 to remove artificial bad blocks created with the "markbad" command. 309 310 "torture offset" 311 Torture block to determine if it is still reliable. 312 Enabled by the CONFIG_CMD_NAND_TORTURE configuration option. 313 This command returns 0 if the block is still reliable, else 1. 314 If the block is detected as unreliable, it is up to the user to decide to 315 mark this block as bad. 316 The analyzed block is put through 3 erase / write cycles (or less if the block 317 is detected as unreliable earlier). 318 This command can be used in scripts, e.g. together with the markbad command to 319 automate retries and handling of possibly newly detected bad blocks if the 320 nand write command fails. 321 It can also be used manually by users having seen some NAND errors in logs to 322 search the root cause of these errors. 323 The underlying nand_torture() function is also useful for code willing to 324 automate actions following a nand->write() error. This would e.g. be required 325 in order to program or update safely firmware to NAND, especially for the UBI 326 part of such firmware. 327 328 329NAND locking command (for chips with active LOCKPRE pin) 330 331 "nand lock" 332 set NAND chip to lock state (all pages locked) 333 334 "nand lock tight" 335 set NAND chip to lock tight state (software can't change locking anymore) 336 337 "nand lock status" 338 displays current locking status of all pages 339 340 "nand unlock [offset] [size]" 341 unlock consecutive area (can be called multiple times for different areas) 342 343 "nand unlock.allexcept [offset] [size]" 344 unlock all except specified consecutive area 345 346I have tested the code with board containing 128MiB NAND large page chips 347and 32MiB small page chips. 348