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.