dt-bindings: arm: Add remote etm dt-binding

Remote ETM(Embedded Trace Macrocell) is to capture information of
the executed processor instructions of remote processors like modem.
Add new coresight-remote-etm.yaml file describing the bindings
required to define coresight remote etm in the device trees.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
Link: https://lore.kernel.org/r/20231210072633.4243-2-quic_jinlmao@quicinc.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/qcom,coresight-remote-etm.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/qcom,coresight-remote-etm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Coresight Remote ETM(Embedded Trace Macrocell)
+
+maintainers:
+  - Jinlong Mao <quic_jinlmao@quicinc.com>
+  - Tao Zhang <quic_taozha@quicinc.com>
+
+description:
+  Support for ETM trace collection on remote processor using coresight
+  framework. Enabling this will allow turning on ETM tracing on remote
+  processor like modem processor via sysfs and collecting the trace
+  via coresight TMC sinks.
+
+properties:
+  compatible:
+    const: qcom,coresight-remote-etm
+
+  out-ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+    additionalProperties: false
+
+    properties:
+      port:
+        description: Output connection to the CoreSight Trace bus.
+        $ref: /schemas/graph.yaml#/properties/port
+
+required:
+  - compatible
+  - out-ports
+
+additionalProperties: false
+
+examples:
+  - |
+    etm {
+        compatible = "qcom,coresight-remote-etm";
+
+        out-ports {
+            port {
+                modem_etm0_out_funnel_modem: endpoint {
+                    remote-endpoint = <&funnel_modem_in_modem_etm0>;
+                };
+            };
+        };
+    };
+...