arm,axi-timing-adapter
Description
The timing adapter is an AXI-to-AXI bridge for providing well-defined
memory timing to allow performance evaluation of an AXI master. The
bridge works by delaying the responses from the memory or, when
enabled, clock-gating the DUT to simulate faster access times as
observed from the DUT, according to run-time configurable parameters
that can be set in the timing adapter. Parameters include read and
write response latencies, number of outstanding transactions, and a
model of interfering traffic.
- Common tuning parameters (most users will adjust these):
- maxr, maxw, maxrw
- rlatency, wlatency
- pulse-on, pulse-off
- bwcap
- Other parameters are available for completeness or specialized use
(e.g. mode, performance counters, histograms). They are typically
left at defaults.
- Performance counter: When measuring from outside the NPU, the
performance counter can be used to count DUT clock-off cycles.
See timing_adapter_perfctrl_settings in the official driver:
https://gitlab.arm.com/artificial-intelligence/ethos-u/
ethos-u-core-platform/-/blob/main/drivers/timing_adapter/
include/timing_adapter.h
Properties
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
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Optional TA block version (informational).
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6-bit. Maximum number of pending read operations allowed.
0 is inferred as infinite. [Common tuning parameter]
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6-bit. Maximum number of pending write operations allowed.
0 is inferred as infinite. [Common tuning parameter]
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6-bit. Maximum number of pending read and write operations combined.
0 is inferred as infinite. [Common tuning parameter]
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12-bit. Minimum latency, in cycles, for a read operation.
This is the duration between ARVALID and RVALID signals.
[Common tuning parameter]
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12-bit. Minimum latency, in cycles, for a write operation.
This is the duration between WVALID and WLAST, with BVALID being deasserted.
[Common tuning parameter]
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Number of cycles where addresses are let through
in a pulse window (0-65535). [Common tuning parameter]
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Number of cycles where addresses are blocked
in a pulse window (0-65535). [Common tuning parameter]
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16-bit. Maximum number of bus words transferred per pulse cycle. A pulse cycle is defined by pulse-on and pulse-off. 0 is inferred as infinite. A bus word is 64 bits on Ethos-U55, and 128 bits on Ethos-U65/U85. [Common tuning parameter]
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6-bit event selector for the performance counter.
Commonly used to count DUT clock-on/off cycles when profiling from
outside the NPU. See the official driver's timing_adapter_perfctrl_settings
for enumerated values.
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32-bit performance counter preload/reset value.
Optional preload before measurement; read back after the run when
perfctrl is configured (e.g. to count DUT clock-off cycles).
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Timing adapter operation mode (bits 0-11).
On FVP only bit 0 is implemented; other bits are ignored/reserved.
Bit 0 controls dynamic clocking:
0 = static clocking (no dynamic adjustment).
1 = dynamic clocking enabled to avoid underrun (recommended).
Bit 1: 1 = enable random AR reordering (0 = default).
Bit 2: 1 = enable random R reordering (0 = default).
Bit 3: 1 = enable random B reordering (0 = default).
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Histogram bin selector (0-15).
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Histogram bin value (32-bit).
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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 “arm,axi-timing-adapter” compatible.
Name |
Type |
Details |
|---|---|---|
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TA base address
This property is required. See Important properties for more information. |
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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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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.
See Important properties for more information. |
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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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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
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Optional names given to each clock provider in the "clocks" property.
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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.
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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.
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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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HW spinlock id relevant to the device.
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Optional names given to the hwlock specifiers in the "hwlocks" 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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