doc/README.nand - platform/external/u-boot - Gitiles

 # SPDX-License-Identifier: GPL-2.0+
 NAND FLASH commands and notes

 See NOTE below!!!

 # (C) Copyright 2003
 # Dave Ellis, SIXNET, dge@sixnetio.com
 #

 Commands:

    nand bad
       Print a list of all of the bad blocks in the current device.

    nand device
       Print information about the current NAND device.

    nand device num
       Make device `num' the current device and print information about it.

    nand erase off|partition size
    nand erase clean [off|partition size]
       Erase `size' bytes starting at offset `off'. Alternatively partition
       name can be specified, in this case size will be eventually limited
       to not exceed partition size (this behaviour applies also to read
       and write commands). Only complete erase blocks can be erased.

       If `erase' is specified without an offset or size, the entire flash
       is erased. If `erase' is specified with partition but without an
       size, the entire partition is erased.

       If `clean' is specified, a JFFS2-style clean marker is written to
       each block after it is erased.

       This command will not erase blocks that are marked bad. There is
       a debug option in cmd_nand.c to allow bad blocks to be erased.
       Please read the warning there before using it, as blocks marked
       bad by the manufacturer must _NEVER_ be erased.

    nand info
       Print information about all of the NAND devices found.

    nand read addr ofs|partition size
       Read `size' bytes from `ofs' in NAND flash to `addr'.  Blocks that
       are marked bad are skipped.  If a page cannot be read because an
       uncorrectable data error is found, the command stops with an error.

    nand read.oob addr ofs|partition size
       Read `size' bytes from the out-of-band data area corresponding to
       `ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
       data for one 512-byte page or 2 256-byte pages. There is no check
       for bad blocks or ECC errors.

    nand write addr ofs|partition size
       Write `size' bytes from `addr' to `ofs' in NAND flash.  Blocks that
       are marked bad are skipped.  If a page cannot be read because an
       uncorrectable data error is found, the command stops with an error.

       As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
       as long as the image is short enough to fit even after skipping the
       bad blocks.  Compact images, such as those produced by mkfs.jffs2
       should work well, but loading an image copied from another flash is
       going to be trouble if there are any bad blocks.

    nand write.trimffs addr ofs|partition size
       Enabled by the CONFIG_CMD_NAND_TRIMFFS macro. This command will write to
       the NAND flash in a manner identical to the 'nand write' command
       described above -- with the additional check that all pages at the end
       of eraseblocks which contain only 0xff data will not be written to the
       NAND flash. This behaviour is required when flashing UBI images
       containing UBIFS volumes as per the UBI FAQ[1].

       [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo

    nand write.oob addr ofs|partition size
       Write `size' bytes from `addr' to the out-of-band data area
       corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
       of data for one 512-byte page or 2 256-byte pages. There is no check
       for bad blocks.

    nand read.raw addr ofs|partition [count]
    nand write.raw addr ofs|partition [count]
       Read or write one or more pages at "ofs" in NAND flash, from or to
       "addr" in memory.  This is a raw access, so ECC is avoided and the
       OOB area is transferred as well.  If count is absent, it is assumed
       to be one page.  As with .yaffs2 accesses, the data is formatted as
       a packed sequence of "data, oob, data, oob, ..." -- no alignment of
       individual pages is maintained.

 Configuration Options:

    CONFIG_SYS_NAND_U_BOOT_OFFS
 	NAND Offset from where SPL will read u-boot image. This is the starting
 	address of u-boot MTD partition in NAND.

    CONFIG_CMD_NAND
       Enables NAND support and commands.

    CONFIG_CMD_NAND_TORTURE
       Enables the torture command (see description of this command below).

    CONFIG_SYS_NAND_MAX_CHIPS
       The maximum number of NAND chips per device to be supported.

    CONFIG_SYS_NAND_SELF_INIT
       Traditionally, glue code in drivers/mtd/nand/raw/nand.c has driven
       the initialization process -- it provides the mtd and nand
       structs, calls a board init function for a specific device,
       calls nand_scan(), and registers with mtd.

       This arrangement does not provide drivers with the flexibility to
       run code between nand_scan_ident() and nand_scan_tail(), or other
       deviations from the "normal" flow.

       If a board defines CONFIG_SYS_NAND_SELF_INIT, drivers/mtd/nand/raw/nand.c
       will make one call to board_nand_init(), with no arguments.  That
       function is responsible for calling a driver init function for
       each NAND device on the board, that performs all initialization
       tasks except setting mtd->name, and registering with the rest of
       U-Boot.  Those last tasks are accomplished by calling  nand_register()
       on the new mtd device.

       Example of new init to be added to the end of an existing driver
       init:

 	/* chip is struct nand_chip, and is now provided by the driver. */
 	mtd = nand_to_mtd(&chip);

 	/*
 	 * Fill in appropriate values if this driver uses these fields,
 	 * or uses the standard read_byte/write_buf/etc. functions from
 	 * nand_base.c that use these fields.
 	 */
 	chip.IO_ADDR_R = ...;
 	chip.IO_ADDR_W = ...;

 	if (nand_scan_ident(mtd, CFG_SYS_MAX_NAND_CHIPS, NULL))
 		error out

 	/*
 	 * Insert here any code you wish to run after the chip has been
 	 * identified, but before any other I/O is done.
 	 */

 	if (nand_scan_tail(mtd))
 		error out

 	/*
 	 * devnum is the device number to be used in nand commands
 	 * and in mtd->name.  Must be less than CONFIG_SYS_MAX_NAND_DEVICE.
 	 */
 	if (nand_register(devnum, mtd))
 		error out

       In addition to providing more flexibility to the driver, it reduces
       the difference between a U-Boot driver and its Linux counterpart.
       nand_init() is now reduced to calling board_nand_init() once, and
       printing a size summary.  This should also make it easier to
       transition to delayed NAND initialization.

       Please convert your driver even if you don't need the extra
       flexibility, so that one day we can eliminate the old mechanism.


 Platform specific options
 =========================
    CONFIG_NAND_OMAP_GPMC
 	Enables omap_gpmc.c driver for OMAPx and AMxxxx platforms.
 	GPMC controller is used for parallel NAND flash devices, and can
 	do ECC calculation (not ECC error detection) for HAM1, BCH4, BCH8
 	and BCH16 ECC algorithms.

    CONFIG_NAND_OMAP_ELM
 	Enables omap_elm.c driver for OMAPx and AMxxxx platforms.
 	ELM controller is used for ECC error detection (not ECC calculation)
 	of BCH4, BCH8 and BCH16 ECC algorithms.
 	Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
 	thus such SoC platforms need to depend on software library for ECC error
 	detection. However ECC calculation on such plaforms would still be
 	done by GPMC controller.

    CONFIG_SPL_NAND_AM33XX_BCH
 	Enables SPL-NAND driver (am335x_spl_bch.c) which supports ELM based
         hardware ECC correction. This is useful for platforms which have ELM
 	hardware engine and use NAND boot mode.
 	Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
 	so those platforms should use CONFIG_SPL_NAND_SIMPLE for enabling
         SPL-NAND driver with software ECC correction support.

     CONFIG_NAND_OMAP_GPMC_PREFETCH
 	On OMAP platforms that use the GPMC controller
 	(CONFIG_NAND_OMAP_GPMC_PREFETCH), this options enables the code that
 	uses the prefetch mode to speed up read operations.

 NOTE:
 =====

 The Disk On Chip driver is currently broken and has been for some time.
 There is a driver in drivers/mtd/nand/raw, taken from Linux, that works with
 the current NAND system but has not yet been adapted to the u-boot
 environment.

 Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006

 JFFS2 related commands:

   implement "nand erase clean" and old "nand erase"
   using both the new code which is able to skip bad blocks
   "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.

 Miscellaneous and testing commands:
   "markbad [offset]"
   create an artificial bad block (for testing bad block handling)

   "scrub [offset length]"
   like "erase" but don't skip bad block. Instead erase them.
   DANGEROUS!!! Factory set bad blocks will be lost. Use only
   to remove artificial bad blocks created with the "markbad" command.

   "torture offset [size]"
   Torture block to determine if it is still reliable.
   Enabled by the CONFIG_CMD_NAND_TORTURE configuration option.
   This command returns 0 if the block is still reliable, else 1.
   If the block is detected as unreliable, it is up to the user to decide to
   mark this block as bad.
   The analyzed block is put through 3 erase / write cycles (or less if the block
   is detected as unreliable earlier).
   This command can be used in scripts, e.g. together with the markbad command to
   automate retries and handling of possibly newly detected bad blocks if the
   nand write command fails.
   It can also be used manually by users having seen some NAND errors in logs to
   search the root cause of these errors.
   The underlying nand_torture() function is also useful for code willing to
   automate actions following a nand->write() error. This would e.g. be required
   in order to program or update safely firmware to NAND, especially for the UBI
   part of such firmware.
   Optionally, a second parameter size can be given to test multiple blocks with
   one call. If size is not a multiple of the NAND's erase size, then the block
   that contains offset + size will be tested in full. If used with size, this
   command returns 0 if all tested blocks have been found reliable, else 1.


 NAND locking command (for chips with active LOCKPRE pin)

   "nand lock"
   set NAND chip to lock state (all pages locked)

   "nand lock tight"
   set NAND chip to lock tight state (software can't change locking anymore)

   "nand lock status"
   displays current locking status of all pages

   "nand unlock [offset] [size]"
   unlock consecutive area (can be called multiple times for different areas)

   "nand unlock.allexcept [offset] [size]"
   unlock all except specified consecutive area

 I have tested the code with board containing 128MiB NAND large page chips
 and 32MiB small page chips.
	# SPDX-License-Identifier: GPL-2.0+
	NAND FLASH commands and notes

	See NOTE below!!!

	# (C) Copyright 2003
	# Dave Ellis, SIXNET, dge@sixnetio.com
	#

	Commands:

	nand bad
	Print a list of all of the bad blocks in the current device.

	nand device
	Print information about the current NAND device.

	nand device num
	Make device `num' the current device and print information about it.

	nand erase off\|partition size
	nand erase clean [off\|partition size]
	Erase `size' bytes starting at offset `off'. Alternatively partition
	name can be specified, in this case size will be eventually limited
	to not exceed partition size (this behaviour applies also to read
	and write commands). Only complete erase blocks can be erased.

	If `erase' is specified without an offset or size, the entire flash
	is erased. If `erase' is specified with partition but without an
	size, the entire partition is erased.

	If `clean' is specified, a JFFS2-style clean marker is written to
	each block after it is erased.

	This command will not erase blocks that are marked bad. There is
	a debug option in cmd_nand.c to allow bad blocks to be erased.
	Please read the warning there before using it, as blocks marked
	bad by the manufacturer must _NEVER_ be erased.

	nand info
	Print information about all of the NAND devices found.

	nand read addr ofs\|partition size
	Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that
	are marked bad are skipped. If a page cannot be read because an
	uncorrectable data error is found, the command stops with an error.

	nand read.oob addr ofs\|partition size
	Read `size' bytes from the out-of-band data area corresponding to
	`ofs' in NAND flash to `addr'. This is limited to the 16 bytes of
	data for one 512-byte page or 2 256-byte pages. There is no check
	for bad blocks or ECC errors.

	nand write addr ofs\|partition size
	Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that
	are marked bad are skipped. If a page cannot be read because an
	uncorrectable data error is found, the command stops with an error.

	As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
	as long as the image is short enough to fit even after skipping the
	bad blocks. Compact images, such as those produced by mkfs.jffs2
	should work well, but loading an image copied from another flash is
	going to be trouble if there are any bad blocks.

	nand write.trimffs addr ofs\|partition size
	Enabled by the CONFIG_CMD_NAND_TRIMFFS macro. This command will write to
	the NAND flash in a manner identical to the 'nand write' command
	described above -- with the additional check that all pages at the end
	of eraseblocks which contain only 0xff data will not be written to the
	NAND flash. This behaviour is required when flashing UBI images
	containing UBIFS volumes as per the UBI FAQ[1].

	[1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo

	nand write.oob addr ofs\|partition size
	Write `size' bytes from `addr' to the out-of-band data area
	corresponding to `ofs' in NAND flash. This is limited to the 16 bytes
	of data for one 512-byte page or 2 256-byte pages. There is no check
	for bad blocks.

	nand read.raw addr ofs\|partition [count]
	nand write.raw addr ofs\|partition [count]
	Read or write one or more pages at "ofs" in NAND flash, from or to
	"addr" in memory. This is a raw access, so ECC is avoided and the
	OOB area is transferred as well. If count is absent, it is assumed
	to be one page. As with .yaffs2 accesses, the data is formatted as
	a packed sequence of "data, oob, data, oob, ..." -- no alignment of
	individual pages is maintained.

	Configuration Options:

	CONFIG_SYS_NAND_U_BOOT_OFFS
	NAND Offset from where SPL will read u-boot image. This is the starting
	address of u-boot MTD partition in NAND.

	CONFIG_CMD_NAND
	Enables NAND support and commands.

	CONFIG_CMD_NAND_TORTURE
	Enables the torture command (see description of this command below).

	CONFIG_SYS_NAND_MAX_CHIPS
	The maximum number of NAND chips per device to be supported.

	CONFIG_SYS_NAND_SELF_INIT
	Traditionally, glue code in drivers/mtd/nand/raw/nand.c has driven
	the initialization process -- it provides the mtd and nand
	structs, calls a board init function for a specific device,
	calls nand_scan(), and registers with mtd.

	This arrangement does not provide drivers with the flexibility to
	run code between nand_scan_ident() and nand_scan_tail(), or other
	deviations from the "normal" flow.

	If a board defines CONFIG_SYS_NAND_SELF_INIT, drivers/mtd/nand/raw/nand.c
	will make one call to board_nand_init(), with no arguments. That
	function is responsible for calling a driver init function for
	each NAND device on the board, that performs all initialization
	tasks except setting mtd->name, and registering with the rest of
	U-Boot. Those last tasks are accomplished by calling nand_register()
	on the new mtd device.

	Example of new init to be added to the end of an existing driver
	init:

	/* chip is struct nand_chip, and is now provided by the driver. */
	mtd = nand_to_mtd(&chip);

	/*
	* Fill in appropriate values if this driver uses these fields,
	* or uses the standard read_byte/write_buf/etc. functions from
	* nand_base.c that use these fields.
	*/
	chip.IO_ADDR_R = ...;
	chip.IO_ADDR_W = ...;

	if (nand_scan_ident(mtd, CFG_SYS_MAX_NAND_CHIPS, NULL))
	error out

	/*
	* Insert here any code you wish to run after the chip has been
	* identified, but before any other I/O is done.
	*/

	if (nand_scan_tail(mtd))
	error out

	/*
	* devnum is the device number to be used in nand commands
	* and in mtd->name. Must be less than CONFIG_SYS_MAX_NAND_DEVICE.
	*/
	if (nand_register(devnum, mtd))
	error out

	In addition to providing more flexibility to the driver, it reduces
	the difference between a U-Boot driver and its Linux counterpart.
	nand_init() is now reduced to calling board_nand_init() once, and
	printing a size summary. This should also make it easier to
	transition to delayed NAND initialization.

	Please convert your driver even if you don't need the extra
	flexibility, so that one day we can eliminate the old mechanism.


	Platform specific options
	=========================
	CONFIG_NAND_OMAP_GPMC
	Enables omap_gpmc.c driver for OMAPx and AMxxxx platforms.
	GPMC controller is used for parallel NAND flash devices, and can
	do ECC calculation (not ECC error detection) for HAM1, BCH4, BCH8
	and BCH16 ECC algorithms.

	CONFIG_NAND_OMAP_ELM
	Enables omap_elm.c driver for OMAPx and AMxxxx platforms.
	ELM controller is used for ECC error detection (not ECC calculation)
	of BCH4, BCH8 and BCH16 ECC algorithms.
	Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
	thus such SoC platforms need to depend on software library for ECC error
	detection. However ECC calculation on such plaforms would still be
	done by GPMC controller.

	CONFIG_SPL_NAND_AM33XX_BCH
	Enables SPL-NAND driver (am335x_spl_bch.c) which supports ELM based
	hardware ECC correction. This is useful for platforms which have ELM
	hardware engine and use NAND boot mode.
	Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
	so those platforms should use CONFIG_SPL_NAND_SIMPLE for enabling
	SPL-NAND driver with software ECC correction support.

	CONFIG_NAND_OMAP_GPMC_PREFETCH
	On OMAP platforms that use the GPMC controller
	(CONFIG_NAND_OMAP_GPMC_PREFETCH), this options enables the code that
	uses the prefetch mode to speed up read operations.

	NOTE:
	=====

	The Disk On Chip driver is currently broken and has been for some time.
	There is a driver in drivers/mtd/nand/raw, taken from Linux, that works with
	the current NAND system but has not yet been adapted to the u-boot
	environment.

	Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006

	JFFS2 related commands:

	implement "nand erase clean" and old "nand erase"
	using both the new code which is able to skip bad blocks
	"nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.

	Miscellaneous and testing commands:
	"markbad [offset]"
	create an artificial bad block (for testing bad block handling)

	"scrub [offset length]"
	like "erase" but don't skip bad block. Instead erase them.
	DANGEROUS!!! Factory set bad blocks will be lost. Use only
	to remove artificial bad blocks created with the "markbad" command.

	"torture offset [size]"
	Torture block to determine if it is still reliable.
	Enabled by the CONFIG_CMD_NAND_TORTURE configuration option.
	This command returns 0 if the block is still reliable, else 1.
	If the block is detected as unreliable, it is up to the user to decide to
	mark this block as bad.
	The analyzed block is put through 3 erase / write cycles (or less if the block
	is detected as unreliable earlier).
	This command can be used in scripts, e.g. together with the markbad command to
	automate retries and handling of possibly newly detected bad blocks if the
	nand write command fails.
	It can also be used manually by users having seen some NAND errors in logs to
	search the root cause of these errors.
	The underlying nand_torture() function is also useful for code willing to
	automate actions following a nand->write() error. This would e.g. be required
	in order to program or update safely firmware to NAND, especially for the UBI
	part of such firmware.
	Optionally, a second parameter size can be given to test multiple blocks with
	one call. If size is not a multiple of the NAND's erase size, then the block
	that contains offset + size will be tested in full. If used with size, this
	command returns 0 if all tested blocks have been found reliable, else 1.


	NAND locking command (for chips with active LOCKPRE pin)

	"nand lock"
	set NAND chip to lock state (all pages locked)

	"nand lock tight"
	set NAND chip to lock tight state (software can't change locking anymore)

	"nand lock status"
	displays current locking status of all pages

	"nand unlock [offset] [size]"
	unlock consecutive area (can be called multiple times for different areas)

	"nand unlock.allexcept [offset] [size]"
	unlock all except specified consecutive area

	I have tested the code with board containing 128MiB NAND large page chips
	and 32MiB small page chips.