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atmel,at25 (on spi bus)

Vendor: Atmel Corporation

Description

SPI EEPROMs compatible with Atmel's AT25 family

There are multiple vendors manufacturing SPI EEPROMs compatible with the programming model of the
Atmel AT25.

Examples of compatible EEPROM families:
- Microchip AT25xxx
- ST M95xxx

Each of these can be represented by a set of common parameters (EEPROM size, page size, address
width, and timeout) available from the datasheet of the specific EEPROM. The compatible string for
these can list the specific EEPROM vendor and model along with the vendor EEPROM family as long as
the least-specific compatible entry is "atmel,at25".

Example devicetree node describing a ST M95256 EEPROM on the spi0 bus:

  &spi0 {
    status = "okay";

    eeprom@1 {
      compatible = "st,m95256", "st,m95xxx", "atmel,at25";
      reg = <0x1>;
      size = <DT_SIZE_K(32)>;
      pagesize = <64>;
      address-width = <16>;
      spi-max-frequency = <DT_FREQ_M(20)>;
      timeout = <5>;
    };
 };

Properties

Properties not inherited from the base binding file.

Name

Type

Details

size

int

 
Total EEPROM size in bytes

This property is required.

read-only

boolean

 
Disable writes to the EEPROM

pagesize

int

 
EEPROM page size in bytes

This property is required.

address-width

int

 
EEPROM address width in bits

This property is required.

timeout

int

 
EEPROM write cycle timeout in milliseconds

This property is required.

wp-gpios

phandle-array

 
GPIO to which the write-protect pin of the chip is connected.

The device will interpret this signal as active-low.

supply-gpios

phandle-array

 
GPIO specifier that controls power to the device.

This property should be provided when the device has a dedicated
switch that controls power to the device.  The supply state is
entirely the responsibility of the device driver.

Contrast with vin-supply.

vin-supply

phandle

 
Reference to the regulator that controls power to the device.
The referenced devicetree node must have a regulator compatible.

This property should be provided when device power is supplied
by a shared regulator.  The supply state is dependent on the
request status of all devices fed by the regulator.

Contrast with supply-gpios.  If both properties are provided
then the regulator must be requested before the supply GPIOS is
set to an active state, and the supply GPIOS must be set to an
inactive state before releasing the regulator.

spi-max-frequency

int

 
Maximum clock frequency of device's SPI interface in Hz

This property is required.

duplex

int

 
Duplex mode, full or half. By default it's always full duplex thus 0
as this is, by far, the most common mode.
Use the macros not the actual enum value, here is the concordance
list (see dt-bindings/spi/spi.h)
  0    SPI_FULL_DUPLEX
  2048 SPI_HALF_DUPLEX

Legal values: 0, 2048

frame-format

int

 
Motorola or TI frame format. By default it's always Motorola's,
thus 0 as this is, by far, the most common format.
Use the macros not the actual enum value, here is the concordance
list (see dt-bindings/spi/spi.h)
  0     SPI_FRAME_FORMAT_MOTOROLA
  32768 SPI_FRAME_FORMAT_TI

Legal values: 0, 32768

spi-cpol

boolean

 
SPI clock polarity which indicates the clock idle state.
If it is used, the clock idle state is logic high; otherwise, low.

spi-cpha

boolean

 
SPI clock phase that indicates on which edge data is sampled.
If it is used, data is sampled on the second edge; otherwise, on the first edge.

spi-hold-cs

boolean

 
In some cases, it is necessary for the master to manage SPI chip select
under software control, so that multiple spi transactions can be performed
without releasing it. A typical use case is variable length SPI packets
where the first spi transaction reads the length and the second spi transaction
reads length bytes.