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
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
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Total EEPROM size in bytes
This property is required. |
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EEPROM page size in bytes
This property is required. |
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EEPROM address width in bits
This property is required. |
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EEPROM write cycle timeout in milliseconds
This property is required. |
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GPIO to which the write-protect pin of the chip is connected.
The device will interpret this signal as active-low.
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Disable writes to the EEPROM
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Maximum clock frequency of device's SPI interface in Hz
This property is required. |
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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: |
|
|
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: |
|
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SPI clock polarity which indicates the clock idle state.
If it is used, the clock idle state is logic high; otherwise, low.
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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.
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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.
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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.
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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.
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Deprecated node specific properties
Deprecated properties not inherited from the base binding file.
(None)
Base properties
Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “atmel,at25” compatible.
Name |
Type |
Details |
|---|---|---|
|
|
indicates the operational status of a device
Legal values: See Important properties for more information. |
|
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compatible strings
This property is required. See Important properties for more information. |
|
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register space
This property is required. See Important properties for more information. |
|
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name of each register space
|
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interrupts for device
See Important properties for more information. |
|
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extended interrupt specifier for device
|
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name of each interrupt
|
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phandle to interrupt controller node
|
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Human readable string describing the device (used as device_get_binding() argument)
See Important properties for more information. This property is deprecated. |
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Clock gate information
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name of each clock
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number of address cells in reg property
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number of size cells in reg property
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DMA channels specifiers
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Provided names of DMA channel specifiers
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IO channels specifiers
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Provided names of IO channel specifiers
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mailbox / IPM channels specifiers
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Provided names of mailbox / IPM channel specifiers
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Power domain specifiers
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Provided names of power domain specifiers
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Number of cells in power-domains property
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Do not initialize device automatically on boot. Device should be manually
initialized using device_init().
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Property to identify that a device can be used as wake up source.
When this property is provided a specific flag is set into the
device that tells the system that the device is capable of
wake up the system.
Wake up capable devices are disabled (interruptions will not wake up
the system) by default but they can be enabled at runtime if necessary.
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Automatically configure the device for runtime power management after the
init function runs.
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List of power states that will disable this device power.
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