xref: /linux/Documentation/ABI/testing/sysfs-class-mtd (revision a9b672e82bca47bf2b37ee869b8095000cf3ca88)

What:		/sys/class/mtd/
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		The mtd/ class subdirectory belongs to the MTD subsystem
		(MTD core).

What:		/sys/class/mtd/mtdX/
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		The /sys/class/mtd/mtd{0,1,2,3,...} directories correspond
		to each /dev/mtdX character device.  These may represent
		physical/simulated flash devices, partitions on a flash
		device, or concatenated flash devices.  They exist regardless
		of whether CONFIG_MTD_CHAR is actually enabled.

What:		/sys/class/mtd/mtdXro/
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		These directories provide the corresponding read-only device
		nodes for /sys/class/mtd/mtdX/ .  They are only created
		(for the benefit of udev) if CONFIG_MTD_CHAR is enabled.

What:		/sys/class/mtd/mtdX/dev
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		Major and minor numbers of the character device corresponding
		to this MTD device (in <major>:<minor> format).  This is the
		read-write device so <minor> will be even.

What:		/sys/class/mtd/mtdXro/dev
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		Major and minor numbers of the character device corresponding
		to the read-only variant of thie MTD device (in
		<major>:<minor> format).  In this case <minor> will be odd.

What:		/sys/class/mtd/mtdX/erasesize
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		"Major" erase size for the device.  If numeraseregions is
		zero, this is the eraseblock size for the entire device.
		Otherwise, the MEMGETREGIONCOUNT/MEMGETREGIONINFO ioctls
		can be used to determine the actual eraseblock layout.

What:		/sys/class/mtd/mtdX/flags
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		A hexadecimal value representing the device flags, ORed
		together:

		0x0400: MTD_WRITEABLE - device is writable
		0x0800: MTD_BIT_WRITEABLE - single bits can be flipped
		0x1000: MTD_NO_ERASE - no erase necessary
		0x2000: MTD_POWERUP_LOCK - always locked after reset

What:		/sys/class/mtd/mtdX/name
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		A human-readable ASCII name for the device or partition.
		This will match the name in /proc/mtd .

What:		/sys/class/mtd/mtdX/numeraseregions
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		For devices that have variable eraseblock sizes, this
		provides the total number of erase regions.  Otherwise,
		it will read back as zero.

What:		/sys/class/mtd/mtdX/oobsize
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		Number of OOB bytes per page.

What:		/sys/class/mtd/mtdX/size
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		Total size of the device/partition, in bytes.

What:		/sys/class/mtd/mtdX/type
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		One of the following ASCII strings, representing the device
		type:

		absent, ram, rom, nor, nand, dataflash, ubi, unknown

What:		/sys/class/mtd/mtdX/writesize
Date:		April 2009
KernelVersion:	2.6.29
Contact:	linux-mtd@lists.infradead.org
Description:
		Minimal writable flash unit size.  This will always be
		a positive integer.

		In the case of NOR flash it is 1 (even though individual
		bits can be cleared).

		In the case of NAND flash it is one NAND page (or a
		half page, or a quarter page).

		In the case of ECC NOR, it is the ECC block size.

What:		/sys/class/mtd/mtdX/ecc_strength
Date:		April 2012
KernelVersion:	3.4
Contact:	linux-mtd@lists.infradead.org
Description:
		Maximum number of bit errors that the device is capable of
		correcting within each region covering an ecc step.  This will
		always be a non-negative integer.  Note that some devices will
		have multiple ecc steps within each writesize region.

		In the case of devices lacking any ECC capability, it is 0.