dt-bindings: arm: Add support for Coresight dummy trace

This patch add support for Coresight dummy source and dummy sink trace.

Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230602084149.40031-3-quic_hazha@quicinc.com

Author: Hao Zhang

Documentation/devicetree/bindings/arm/arm,coresight-dummy-sink.yaml

@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/arm,coresight-dummy-sink.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ARM Coresight Dummy sink component
+
+description: |
+  CoreSight components are compliant with the ARM CoreSight architecture
+  specification and can be connected in various topologies to suit a particular
+  SoCs tracing needs. These trace components can generally be classified as
+  sinks, links and sources. Trace data produced by one or more sources flows
+  through the intermediate links connecting the source to the currently selected
+  sink.
+
+  The Coresight dummy sink component is for the specific coresight sink devices
+  kernel don't have permission to access or configure, e.g., CoreSight EUD on
+  Qualcomm platforms. It is a mini-USB hub implemented to support the USB-based
+  debug and trace capabilities. For this device, a dummy driver is needed to
+  register it as Coresight sink device in kernel side, so that path can be
+  created in the driver. Then the trace flow would be transferred to EUD via
+  coresight link of AP processor. It provides Coresight API for operations on
+  dummy source devices, such as enabling and disabling them. It also provides
+  the Coresight dummy source paths for debugging.
+
+  The primary use case of the coresight dummy sink is to build path in kernel
+  side for dummy sink component.
+
+maintainers:
+  - Mike Leach <mike.leach@linaro.org>
+  - Suzuki K Poulose <suzuki.poulose@arm.com>
+  - James Clark <james.clark@arm.com>
+  - Mao Jinlong <quic_jinlmao@quicinc.com>
+  - Hao Zhang <quic_hazha@quicinc.com>
+
+properties:
+  compatible:
+    enum:
+      - arm,coresight-dummy-sink
+
+  in-ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port:
+        description: Input connection from the Coresight Trace bus to
+          dummy sink, such as Embedded USB debugger(EUD).
+
+        $ref: /schemas/graph.yaml#/properties/port
+
+required:
+  - compatible
+  - in-ports
+
+additionalProperties: false
+
+examples:
+  # Minimum dummy sink definition. Dummy sink connect to coresight replicator.
+  - |
+    sink {
+      compatible = "arm,coresight-dummy-sink";
+
+      in-ports {
+        port {
+          eud_in_replicator_swao: endpoint {
+            remote-endpoint = <&replicator_swao_out_eud>;
+          };
+        };
+      };
+    };
+
+...

Documentation/devicetree/bindings/arm/arm,coresight-dummy-source.yaml

@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/arm,coresight-dummy-source.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ARM Coresight Dummy source component
+
+description: |
+  CoreSight components are compliant with the ARM CoreSight architecture
+  specification and can be connected in various topologies to suit a particular
+  SoCs tracing needs. These trace components can generally be classified as
+  sinks, links and sources. Trace data produced by one or more sources flows
+  through the intermediate links connecting the source to the currently selected
+  sink.
+
+  The Coresight dummy source component is for the specific coresight source
+  devices kernel don't have permission to access or configure. For some SOCs,
+  there would be Coresight source trace components on sub-processor which
+  are conneted to AP processor via debug bus. For these devices, a dummy driver
+  is needed to register them as Coresight source devices, so that paths can be
+  created in the driver. It provides Coresight API for operations on dummy
+  source devices, such as enabling and disabling them. It also provides the
+  Coresight dummy source paths for debugging.
+
+  The primary use case of the coresight dummy source is to build path in kernel
+  side for dummy source component.
+
+maintainers:
+  - Mike Leach <mike.leach@linaro.org>
+  - Suzuki K Poulose <suzuki.poulose@arm.com>
+  - James Clark <james.clark@arm.com>
+  - Mao Jinlong <quic_jinlmao@quicinc.com>
+  - Hao Zhang <quic_hazha@quicinc.com>
+
+properties:
+  compatible:
+    enum:
+      - arm,coresight-dummy-source
+
+  out-ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port:
+        description: Output connection from the source to Coresight
+          Trace bus.
+        $ref: /schemas/graph.yaml#/properties/port
+
+required:
+  - compatible
+  - out-ports
+
+additionalProperties: false
+
+examples:
+  # Minimum dummy source definition. Dummy source connect to coresight funnel.
+  - |
+    source {
+      compatible = "arm,coresight-dummy-source";
+
+      out-ports {
+        port {
+          dummy_riscv_out_funnel_swao: endpoint {
+            remote-endpoint = <&funnel_swao_in_dummy_riscv>;
+          };
+        };
+      };
+    };
+
+...