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 attributes of each supported device, such as block size, sector size, and device  capacity.   When  a
       supported  device  is  found,  the  at45d  driver  creates  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:

       •   AT45DB011B
       •   AT45DB021B
       •   AT45DB041x
       •   AT45DB081B
       •   AT45DB161x
       •   AT45DB321x
       •   AT45DB321x
       •   AT45DB641E
       •   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 configurable 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 device.  Actual bus  speed  may  be
               lower, depending on the capabilities of the SPI bus controller hardware.

       hint.at45d.%d.cs
               The chip-select number to assert when performing I/O for this device.  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.

Debian                                            March 2, 2019                                         AT45D(4)