Re: [PATCH V2 06/11] dts: bindings: Document device tree bindings for ETE
From: Rob Herring <robh@kernel.org>
Date: 2021-01-25 19:46:41
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On Wed, Jan 13, 2021 at 09:48:13AM +0530, Anshuman Khandual wrote:
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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 <redacted> Cc: Rob Herring <robh@kernel.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Anshuman Khandual <redacted> --- Documentation/devicetree/bindings/arm/ete.yaml | 71 ++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/ete.yamldiff --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>;
+ };
+ };
+ };
+ };
+
+...
--
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