freebsd-skq/share/man/man4/nand.4

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.Dd March 8, 2012
.Dt NAND 4
.Os
.Sh NAME
.Nm nand
.Nd NAND Flash framework
.Sh SYNOPSIS
.Cd "device nand"
.Sh DESCRIPTION
The
.Fx
.Nm
framework consists of a set of interfaces that aim to provide an extensible,
object oriented environment 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:
.Bl -bullet
.It
NAND Flash controller (NFC) interface.
.Pp
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.
.Pp
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.
.It
NAND chip interface.
.Pp
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:
.Bl -bullet
.It
large page
.It
small page
.It
ONFI-compliant
.El
.Pp
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.
.Pp
The framework is extensible so it is also possible to create a custom command
set for a non standard chip support.
.It
NANDbus.
.Pp
This layer is responsible for enumerating NAND chips in the system and
establishing the hierarchy between chips and their supervising controllers.
.Pp
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.
.It
NAND character / GEOM device.
.Pp
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).
.Pp
There are two GEOM devices created for each NAND chip:
.Bl -bullet
.It
raw device
.It
normal device
.El
.Pp
Raw device allows to bypass ECC checking when reading/writing to it, while
normal device always uses ECC algorithm to validate the read data.
.Pp
NAND character devices will be created for each NAND chip detected while
probing the NAND controller.
.El
.Sh SEE ALSO
.Xr libnandfs 3 ,
.Xr gnand 4 ,
.Xr nandsim 4 ,
.Xr nandfs 5 ,
.Xr makefs 8 ,
.Xr mount_nandfs 8 ,
.Xr nandfs 8 ,
.Xr nandsim 8 ,
.Xr nandtool 8 ,
.Xr newfs_nandfs 8 ,
.Xr umount_nandfs 8
.Sh STANDARDS
Open NAND Flash Interface Working Group
.Pq Vt ONFI .
.Sh HISTORY
The
.Nm
framework support first appeared in
.Fx 10.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
framework was designed and developed by
.An Grzegorz Bernacki .
This manual page was written by
.An Rafal Jaworowski .