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742ca2307f
This change makes AMU auxiliary counters configurable on a per-core
basis, controlled by `ENABLE_AMU_AUXILIARY_COUNTERS`.
Auxiliary counters can be described via the `HW_CONFIG` device tree if
the `ENABLE_AMU_FCONF` build option is enabled, or the platform must
otherwise implement the `plat_amu_topology` function.
A new phandle property for `cpu` nodes (`amu`) has been introduced to
the `HW_CONFIG` specification to allow CPUs to describe the view of
their own AMU:
```
cpu0: cpu@0 {
...
amu = <&cpu0_amu>;
};
```
Multiple cores may share an `amu` handle if they implement the
same set of auxiliary counters.
AMU counters are described for one or more AMUs through the use of a new
`amus` node:
```
amus {
cpu0_amu: amu-0 {
#address-cells = <1>;
#size-cells = <0>;
counter@0 {
reg = <0>;
enable-at-el3;
};
counter@n {
reg = <n>;
...
};
};
};
```
This structure describes the **auxiliary** (group 1) AMU counters.
Architected counters have architecturally-defined behaviour, and as
such do not require DTB entries.
These `counter` nodes support two properties:
- The `reg` property represents the counter register index.
- The presence of the `enable-at-el3` property determines whether
the firmware should enable the counter prior to exiting EL3.
Change-Id: Ie43aee010518c5725a3b338a4899b0857caf4c28
Signed-off-by: Chris Kay <chris.kay@arm.com>
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1.2 KiB
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32 lines
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Activity Monitors
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=================
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FEAT_AMUv1 of the Armv8-A architecture introduces the Activity Monitors
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extension. This extension describes the architecture for the Activity Monitor
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Unit (|AMU|), an optional non-invasive component for monitoring core events
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through a set of 64-bit counters.
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When the ``ENABLE_AMU=1`` build option is provided, Trusted Firmware-A sets up
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the |AMU| prior to its exit from EL3, and will save and restore architected
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|AMU| counters as necessary upon suspend and resume.
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Auxiliary counters
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------------------
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FEAT_AMUv1 describes a set of implementation-defined auxiliary counters (also
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known as group 1 counters), controlled by the ``ENABLE_AMU_AUXILIARY_COUNTERS``
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build option.
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As a security precaution, Trusted Firmware-A does not enable these by default.
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Instead, platforms may configure their auxiliary counters through one of two
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possible mechanisms:
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- |FCONF|, controlled by the ``ENABLE_AMU_FCONF`` build option.
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- A platform implementation of the ``plat_amu_topology`` function (the default).
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See :ref:`Activity Monitor Unit (AMU) Bindings` for documentation on the |FCONF|
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device tree bindings.
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--------------
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*Copyright (c) 2021, Arm Limited. All rights reserved.*
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