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AT45D(4)		 BSD Kernel Interfaces Manual		      AT45D(4)

NAME
     at45d -- driver for DataFlash(tm) non-volatile storage devices

SYNOPSIS
     To	compile	this driver into the kernel, place the following line in your
     kernel configuration file:

	   device at45d

     Alternatively, to load the	driver as a module at boot time, place the
     following line in loader.conf(5):

	   at45d_load="YES"

DESCRIPTION
     The at45d driver provides support for the family of non-volatile storage
     devices known collectively	as DataFlash(tm).  DataFlash chips typically
     have part numbers beginning with AT45DB.  The at45d driver	supports only
     the SPI bus versions of each AT45DB device, indicated by the last digit
     of	the part number	being 1	or 2.

     The at45d driver uses opcode 0x9f to read the manufacturer	and device ID
     data to determine whether the device is supported.	 The device ID is
     looked up using a table of	data within the	driver which describes the at-
     tributes of each supported	device,	such as	block size, sector size, and
     device capacity.  When a supported	device is found, the at45d driver cre-
     ates a disk device	and makes it accessible	at /dev/flash/at45d?.  The new
     disk device is then tasted	by the available geom(4) modules as with any
     disk device.

HARDWARE
     The at45d driver provides support for the following devices:

     +o	 AT45DB011B
     +o	 AT45DB021B
     +o	 AT45DB041x
     +o	 AT45DB081B
     +o	 AT45DB161x
     +o	 AT45DB321x
     +o	 AT45DB321x
     +o	 AT45DB641E
     +o	 AT45DB642x

FDT CONFIGURATION
     On	an fdt(4) based	system,	the at45d device is defined as a slave device
     subnode of	the SPI	bus controller node.  All properties documented	in the
     spibus.txt	bindings document can be used with the at45d device.  The most
     commonly-used ones	are documented below.

     The following properties are required in the at45d	device subnode:

     compatible
	     Must be the string	"atmel,at45".

     reg     Chip select address of device.

     spi-max-frequency
	     The maximum bus frequency to use when communicating with this
	     slave device.  Actual bus speed may be lower, depending on	the
	     capabilities of the SPI bus controller hardware.

     The following properties are optional for the at45d device	subnode:

     freebsd,sectorsize
	     The sector	size of	the disk created for this storage device.  It
	     must be a multiple	of the device's	page size.  The	default	is the
	     device page size.

     spi-cpha
	     Empty property indicating the slave device	requires shifted clock
	     phase (CPHA) mode.

     spi-cpol
	     Empty property indicating the slave device	requires inverse clock
	     polarity (CPOL) mode.

     spi-cs-high
	     Empty property indicating the slave device	requires chip select
	     active high.

HINTS CONFIGURATION
     On	a device.hints(5) based	system,	such as	MIPS, these values are config-
     urable for	at45d:

     hint.at45d.%d.at
	     The spibus	the at45d instance is attached to.

     hint.at45d.%d.clock
	     The maximum bus frequency to use when communicating with this de-
	     vice.  Actual bus speed may be lower, depending on	the capabili-
	     ties of the SPI bus controller hardware.

     hint.at45d.%d.cs
	     The chip-select number to assert when performing I/O for this de-
	     vice.  Set	the high bit (1	<< 31) to invert the logic level of
	     the chip select line.

     hint.at45d.%d.mode
	     The SPI mode (0-3)	to use when communicating with this device.

     hint.at45d.%d.sectorsize
	     The sector	size of	the disk created for this storage device.  It
	     must be a multiple	of the device's	page size.  The	default	is the
	     device page size.

FILES
     /dev/flash/at45d?	Provides read/write access to the storage device.

     /dev/flash/spi?	An alias for the /dev/at45d? device, for backwards
			compatibility with older versions of the driver.

SEE ALSO
     fdt(4), geom(4)

HISTORY
     The at45d driver first appeared in	FreeBSD	6.0.

BSD				 March 2, 2019				   BSD

NAME | SYNOPSIS | DESCRIPTION | HARDWARE | FDT CONFIGURATION | HINTS CONFIGURATION | FILES | SEE ALSO | HISTORY

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