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NAND(4)                FreeBSD Kernel Interfaces Manual                NAND(4)

     nand - NAND Flash framework

     device nand

     The FreeBSD nand framework consists of a set of interfaces that aim to
     provide an extensible, object oriented environement for NAND controllers
     and NAND Flash memory chips from various hardware vendors, and to allow
     for uniform and flexible management of the NAND devices. It comprises of
     the following major components:

     +o   NAND Flash controller (NFC) interface.

         Defines methods which allow to send commands as well as send/receive
         data between the controller and a NAND chip. Back-end drivers for
         specific NAND controllers plug into this interface and implement low-
         level routines for a given NAND controller.

         This layer implements basic functionality of a NAND Flash controller.
         It allows to send command and address to chip, drive CS (chip select
         line), as well as read/write to the selected NAND chip. This layer is
         independent of NAND chip devices actually connected to the

     +o   NAND chip interface.

         Provides basic operations like read page, program page, erase block.
         Currently three generic classes of drivers are available, which
         provide support for the following chips:

         +o   large page

         +o   small page

         +o   ONFI-compliant

         This layer implements basic operations to be performed on a NAND
         chip, like read, program, erase, get status etc. Since these
         operations use specific commands (depending on the vendor), each chip
         has potentially its own implementation of the commands set.

         The framework is extensible so it is also possible to create a custom
         command set for a non standard chip support.

     +o   NANDbus.

         This layer is responsible for enumerating NAND chips in the system
         and establishing the hierarchy between chips and their supervising

         Its main purpose is detecting type of NAND chips connected to a given
         chip select (CS line). It also allows manages locking access to the
         NAND controller. NANDbus passes requests from an active chip to the
         chip controller.

     +o   NAND character / GEOM device.

         For each NAND chip found in a system a character and GEOM devices are
         created which allows to read / write directly to a device, as well as
         perform other specific operations (like via ioctl).

         There are two GEOM devices created for each NAND chip:

         +o   raw device

         +o   normal device

         Raw device allows to bypass ECC checking when reading/writing to it,
         while normal device always uses ECC algorithm to validate the read

         NAND character devices will be created for each NAND chip detected
         while probing the NAND controller.

     libnandfs(3), gnand(4), nandsim(4), nandfs(5), makefs(8),
     mount_nandfs(8), nandfs(8), nandsim(8), nandtool(8), newfs_nandfs(8),

     Open NAND Flash Interface Working Group (ONFI).

     The nand framework support first appeared in FreeBSD 10.0.

     The nand framework was designed and developed by Grzegorz Bernacki.  This
     manual page was written by Rafal Jaworowski.

FreeBSD 11.0-PRERELEASE          March 8, 2012         FreeBSD 11.0-PRERELEASE


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