NAME

       nand — NAND Flash framework

SYNOPSIS

       device nand

DESCRIPTION

       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:

       •   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 controller.

       •   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:

           •   large page

           •   small page

           •   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.

       •   NANDbus.

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

           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.

       •   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:

           •   raw device

           •   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 data.

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

SEE ALSO

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

STANDARDS

       Open NAND Flash Interface Working Group (ONFI).

HISTORY

       The nand framework support first appeared in FreeBSD 10.0.

AUTHORS

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

Debian                                            March 8, 2012                                          NAND(4)