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    SubjectRe: [PATCH V2 06/11] dts: bindings: Document device tree bindings for ETE
    On Wed, Jan 13, 2021 at 09:48:13AM +0530, Anshuman Khandual wrote:
    > From: Suzuki K Poulose <suzuki.poulose@arm.com>
    >
    > Document the device tree bindings for Embedded Trace Extensions.
    > ETE can be connected to legacy coresight components and thus
    > could optionally contain a connection graph as described by
    > the CoreSight bindings.
    >
    > Cc: devicetree@vger.kernel.org
    > Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    > Cc: Mike Leach <mike.leach@linaro.org>
    > Cc: Rob Herring <robh@kernel.org>
    > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
    > ---
    > Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++
    > 1 file changed, 71 insertions(+)
    > create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml
    >
    > diff --git a/Documentation/devicetree/bindings/arm/ete.yaml b/Documentation/devicetree/bindings/arm/ete.yaml
    > new file mode 100644
    > index 0000000..00e6a77
    > --- /dev/null
    > +++ b/Documentation/devicetree/bindings/arm/ete.yaml
    > @@ -0,0 +1,71 @@
    > +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
    > +# Copyright 2021, Arm Ltd
    > +%YAML 1.2
    > +---
    > +$id: "http://devicetree.org/schemas/arm/ete.yaml#"
    > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
    > +
    > +title: ARM Embedded Trace Extensions
    > +
    > +maintainers:
    > + - Suzuki K Poulose <suzuki.poulose@arm.com>
    > + - Mathieu Poirier <mathieu.poirier@linaro.org>
    > +
    > +description: |
    > + Arm Embedded Trace Extension(ETE) is a per CPU trace component that
    > + allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
    > + architecture and has extended support for future architecture changes.
    > + The trace generated by the ETE could be stored via legacy CoreSight
    > + components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
    > + Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
    > + legacy CoreSight components, a node must be listed per instance, along
    > + with any optional connection graph as per the coresight bindings.
    > + See bindings/arm/coresight.txt.
    > +
    > +properties:
    > + $nodename:
    > + pattern: "^ete([0-9a-f]+)$"
    > + compatible:
    > + items:
    > + - const: arm,embedded-trace-extension
    > +
    > + cpu:

    We use 'cpus' in a couple of other places, let's do that here for
    consistency.

    > + description: |
    > + Handle to the cpu this ETE is bound to.
    > + $ref: /schemas/types.yaml#/definitions/phandle
    > +
    > + out-ports:
    > + description: |
    > + Out put connections from the ETE to legacy CoreSight trace bus.

    Output

    > + $ref: /schemas/graph.yaml#/properties/ports

    You have to define what each 'port' is if there can be more than 1. If
    there's only ever 1 then you just need 'port' though maybe all the
    coresight bindings require 'out-ports'. And the port nodes need a $ref
    to '/schemas/graph.yaml#/properties/port'.

    > +
    > +required:
    > + - compatible
    > + - cpu
    > +
    > +additionalProperties: false
    > +
    > +examples:
    > +
    > +# An ETE node without legacy CoreSight connections
    > + - |
    > + ete0 {
    > + compatible = "arm,embedded-trace-extension";
    > + cpu = <&cpu_0>;
    > + };
    > +# An ETE node with legacy CoreSight connections
    > + - |
    > + ete1 {
    > + compatible = "arm,embedded-trace-extension";
    > + cpu = <&cpu_1>;
    > +
    > + out-ports { /* legacy coresight connection */
    > + port {
    > + ete1_out_port: endpoint {
    > + remote-endpoint = <&funnel_in_port0>;
    > + };
    > + };
    > + };
    > + };
    > +
    > +...
    > --
    > 2.7.4
    >

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