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+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.
+
+What: /sys/class/mtd/mtdX/bitflip_threshold
+Date: April 2012
+KernelVersion: 3.4
+Contact: linux-mtd@lists.infradead.org
+Description:
+ This allows the user to examine and adjust the criteria by which
+ mtd returns -EUCLEAN from mtd_read() and mtd_read_oob(). If the
+ maximum number of bit errors that were corrected on any single
+ region comprising an ecc step (as reported by the driver) equals
+ or exceeds this value, -EUCLEAN is returned. Otherwise, absent
+ an error, 0 is returned. Higher layers (e.g., UBI) use this
+ return code as an indication that an erase block may be
+ degrading and should be scrutinized as a candidate for being
+ marked as bad.
+
+ The initial value may be specified by the flash device driver.
+ If not, then the default value is ecc_strength.
+
+ The introduction of this feature brings a subtle change to the
+ meaning of the -EUCLEAN return code. Previously, it was
+ interpreted to mean simply "one or more bit errors were
+ corrected". Its new interpretation can be phrased as "a
+ dangerously high number of bit errors were corrected on one or
+ more regions comprising an ecc step". The precise definition of
+ "dangerously high" can be adjusted by the user with
+ bitflip_threshold. Users are discouraged from doing this,
+ however, unless they know what they are doing and have intimate
+ knowledge of the properties of their device. Broadly speaking,
+ bitflip_threshold should be low enough to detect genuine erase
+ block degradation, but high enough to avoid the consequences of
+ a persistent return value of -EUCLEAN on devices where sticky
+ bitflips occur. Note that if bitflip_threshold exceeds
+ ecc_strength, -EUCLEAN is never returned by the read operations.
+ Conversely, if bitflip_threshold is zero, -EUCLEAN is always
+ returned, absent a hard error.
+
+ This is generally applicable only to NAND flash devices with ECC
+ capability. It is ignored on devices lacking ECC capability;
+ i.e., devices for which ecc_strength is zero.