AT45D(4)               FreeBSD 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
     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.

FreeBSD 13.1-RELEASE-p6          March 2, 2019         FreeBSD 13.1-RELEASE-p6