atmel,sam-i2c-twim
Vendor: Atmel Corporation
Note
An implementation of a driver matching this compatible is available in drivers/i2c/i2c_sam4l_twim.c.
Description
These nodes are “i2c” bus nodes.
Atmel SAM4L Family I2C (TWIM) node
The Atmel Two-wire Master Interface (TWIM) interconnects components on a
unique two-wire bus, made up of one clock line and one data line with speeds
of up to 3.4 Mbit/s, based on a byte-oriented transfer format. The TWIM is
always a bus master and can transfer sequential or single bytes. Multiple
master capability is supported. Arbitration of the bus is performed
internally and relinquishes the bus automatically if the bus arbitration is
lost.
When using speeds above standard mode, user may need adjust clock and data
lines slew and strength parameters. In general, slew 0 and minimal strength
is enough for short buses and light loads. As a reference, the below
is the lowest power configuration:
std-clk-slew-lim = <0>;
std-clk-strength-low = "0.5";
std-data-slew-lim = <0>;
std-data-strength-low = "0.5";
hs-clk-slew-lim = <0>;
hs-clk-strength-high = "0.5";
hs-clk-strength-low = "0.5";
hs-data-slew-lim = <0>;
hs-data-strength-low = "0.5";
For best performances, user can tune the slope curves using an osciloscope.
The tuning should be performed by groups defined <mode>-<line>. The prefix
std-<line> configures fast/fast-plus mode speeds and hs-<line> selects the
high speed mode. The tune should be performed for both clock and data lines
on both speed modes.
Properties
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
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Slew limit of the TWCK output buffer. This should be adjusted with
std-clk-strength-low to fine tune the TWCK slope.
This property is required. Legal values: |
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Pull-down drive strength of the TWCK output buffer in fast/fast plus
mode. This should be adjusted to provide proper TWCK line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
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Slew limit of the TWD output buffer. This should be adjusted with
std-data-strength-low to fine tune the TWD slope.
This property is required. Legal values: |
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Pull-down drive strength of the TWD output buffer in fast/fast plus
mode. This should be adjusted to provide proper TWD line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
|
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Slew limit of the TWCK output buffer in high speed mode. This
should be adjusted with both hs-clk-strength-high and
hs-clk-strength-low to fine tune the TWCK slope.
This property is required. Legal values: |
|
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Pull-up drive strength of the TWCK output buffer in high speed
mode. This should be adjusted to provide proper TWCK line rise time.
The value represents the port output current in mA when signal on
high level.
This property is required. Legal values: |
|
|
Pull-down drive strength of the TWCK output buffer in high speed
mode. This should be adjusted to provide proper TWCK line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
|
|
Slew limit of the TWD output buffer in high speed mode. This
should be adjusted with hs-data-strength-low to fine tune the TWD
slope.
This property is required. Legal values: |
|
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Pull-down drive strength of the TWD output buffer in high speed
mode. This should be adjusted to provide proper TWD line fall time.
The value represents the port output current in mA when signal on
low level.
Legal values: |
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3-bit code to be prefixed with 0b00001 to form a unique
8-bit HS-mode master code (0000 1XXX)
This property is required. Legal values: |
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Initial clock frequency in Hz
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Size of the submission queue for blocking requests
Default value: |
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Size of the completion queue for blocking requests
Default value: |
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Pin configuration/s for the first state. Content is specific to the
selected pin controller driver implementation.
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Pin configuration/s for the second state. See pinctrl-0.
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Pin configuration/s for the third state. See pinctrl-0.
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Pin configuration/s for the fourth state. See pinctrl-0.
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Pin configuration/s for the fifth state. See pinctrl-0.
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Names for the provided states. The number of names needs to match the
number of states.
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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,sam-i2c-twim” compatible.
Name |
Type |
Details |
|---|---|---|
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Information used to address the device. The value is specific to
the device (i.e. is different depending on the compatible
property).
The "reg" property is typically a sequence of (address, length) pairs.
Each pair is called a "register block". Values are
conventionally written in hex.
For details, see "2.3.6 reg" in Devicetree Specification v0.4.
This property is required. See Important properties for more information. |
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Information about interrupts generated by the device, encoded as an array
of one or more interrupt specifiers. The format of the data in this property
varies by where the device appears in the interrupt tree. Devices with the same
"interrupt-parent" will use the same format in their interrupts properties.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
This property is required. See Important properties for more information. |
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Information about the device's clock providers. In general, this property
should follow conventions established in the dt-schema binding:
https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml
This property is required. |
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This property encodes the number of <u32> cells used by address fields
in "reg" properties in this node's children.
For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.
This property is required. Constant value: |
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This property encodes the number of <u32> cells used by size fields in
"reg" properties in this node's children.
For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.
This property is required. |
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Indicates the operational status of the hardware or other
resource that the node represents. In particular:
- "okay" means the resource is operational and, for example,
can be used by device drivers
- "disabled" means the resource is not operational and the system
should treat it as if it is not present
For details, see "2.3.4 status" in Devicetree Specification v0.4.
Legal values: See Important properties for more information. |
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This property is a list of strings that essentially define what
type of hardware or other resource this devicetree node
represents. Each device driver checks for specific compatible
property values to find the devicetree nodes that represent
resources that the driver should manage.
The recommended format is "vendor,device", The "vendor" part is
an abbreviated name of the vendor. The "device" is usually from
the datasheet.
The compatible property can have multiple values, ordered from
most- to least-specific. Having additional values is useful when the
device is a specific instance of a more general family, to allow the
system to match the most specific driver available.
For details, see "2.3.1 compatible" in Devicetree Specification v0.4.
This property is required. See Important properties for more information. |
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Optional names given to each register block in the "reg" property.
For example:
/ {
soc {
#address-cells = <1>;
#size-cells = <1>;
uart@1000 {
reg = <0x1000 0x2000>, <0x3000 0x4000>;
reg-names = "foo", "bar";
};
};
};
The uart@1000 node has two register blocks:
- one with base address 0x1000, size 0x2000, and name "foo"
- another with base address 0x3000, size 0x4000, and name "bar"
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Extended interrupt specifier for device, used as an alternative to
the "interrupts" property.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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Optional names given to each interrupt generated by a device.
The interrupts themselves are defined in either "interrupts" or
"interrupts-extended" properties.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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If present, this refers to the node which handles interrupts generated
by this device.
For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.
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Human readable string describing the device. Use of this property is
deprecated except as needed on a case-by-case basis.
For details, see "4.1.2 Miscellaneous Properties" in Devicetree
Specification v0.4.
See Important properties for more information. |
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Optional names given to each clock provider in the "clocks" property.
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DMA channel specifiers relevant to the device.
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Optional names given to the DMA channel specifiers in the "dmas" property.
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IO channel specifiers relevant to the device.
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Optional names given to the IO channel specifiers in the "io-channels" property.
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Mailbox / IPM channel specifiers relevant to the device.
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Optional names given to the mbox specifiers in the "mboxes" property.
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Power domain specifiers relevant to the device.
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Optional names given to the power domain specifiers in the "power-domains" property.
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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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