[PATCH v2 3/3] Documentation: trace: Add documentation for Coresight Dummy Trace

[Hao Zhang]

Add documentation for Coresight Dummy Trace under trace/coresight.

Signed-off-by: Hao Zhang <quic_hazha at quicinc.com>
---
 .../trace/coresight/coresight-dummy.rst       | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 Documentation/trace/coresight/coresight-dummy.rst

diff --git a/Documentation/trace/coresight/coresight-dummy.rst b/Documentation/trace/coresight/coresight-dummy.rst
new file mode 100644
index 000000000000..819cabab8623
--- /dev/null
+++ b/Documentation/trace/coresight/coresight-dummy.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Coresight Dummy Trace Module
+=============================
+
+    :Author:   Hao Zhang <quic_hazha at quicinc.com>
+    :Date:     March 2023
+
+Introduction
+---------------------------
+
+Coresight Dummy Trace Module is for the specific devices that HLOS don't
+have permission to access or configure. Such as Coresight sink EUD, some
+TPDMs etc. So there need driver to register dummy devices as Coresight
+devices. Provide Coresight API for dummy device operations, such as
+enabling and disabling dummy devices. Build the Coresight path for dummy
+sink or dummy source for debugging.
+
+Sysfs files and directories
+---------------------------
+
+Root: ``/sys/bus/coresight/devices/dummy<N>``
+
+----
+
+:File:            ``enable_source`` (RW)
+:Notes:
+    - > 0 : enable the datasets of dummy source.
+
+    - = 0 : disable the datasets of dummy source.
+
+:Syntax:
+    ``echo 1 > enable_source``
+
+----
+
+:File:            ``enable_sink`` (RW)
+:Notes:
+    - > 0 : enable the datasets of dummy sink.
+
+    - = 0 : disable the datasets of dummy sink.
+
+:Syntax:
+    ``echo 1 > enable_sink``
+
+----
+
+Config details
+---------------------------
+
+There are two types of nodes, dummy sink and dummy source. The nodes
+should be observed at the coresight path
+"/sys/bus/coresight/devices".
+e.g.
+/sys/bus/coresight/devices # ls -l | grep dummy
+dummy0 -> ../../../devices/platform/soc at 0/soc at 0:dummy_source/dummy0
+dummy1 -> ../../../devices/platform/soc at 0/soc at 0:dummy_sink/dummy1
-- 
2.17.1