On Mon, Mar 22, 2021 at 10:53 AM Suzuki K Poulose
[off-list ref] wrote:

Hi Rob

On 06/03/2021 21:06, Rob Herring wrote:

quoted

On Thu, Feb 25, 2021 at 07:35:39PM +0000, Suzuki K Poulose wrote:

quoted

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>
---
Changes:
  - Fix out-ports defintion
---
  .../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 000000000000..35a42d92bf97
--- /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:
+    description: |
+      Handle to the cpu this ETE is bound to.
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+  out-ports:
+    description: |
+      Output connections from the ETE to legacy CoreSight trace bus.
+    $ref: /schemas/graph.yaml#/properties/port

s/port/ports/

Ok.

quoted

And then you need:

        properties:
          port:
            description: what this port is
            $ref: /schemas/graph.yaml#/properties/port

Isn't this already covered by the definition of ports ? There are no
fixed connections for ETE. It is optional and could be connected to
any legacy CoreSight component. i.e, a "ports" object can have port
objects inside.

'properties/ports' only defines that you have 'port' nodes within it.

Given we have defined out-ports as an object "confirming to the ports"
do we need to describe the individual port nodes ?

Yes, you have to define what the 'port' nodes are. A port is a data
stream and you should know what your hardware has. What the data
stream is connected to is outside the scope of the binding.

Rob