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authorHao Zhang <quic_hazha@quicinc.com>2023-06-02 16:41:49 +0800
committerSuzuki K Poulose <suzuki.poulose@arm.com>2023-06-15 08:50:23 +0100
commit3b79104f80036231a40ba5d15c3e329985029a0f (patch)
tree054a8127fc981778c7bf8293e2992688157ece78 /Documentation/trace
parent5911ff4559e45532c1f67257c5731b5e13f5e7a3 (diff)
Documentation: trace: Add documentation for Coresight Dummy Trace
Add documentation for Coresight Dummy Trace under trace/coresight. Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Hao Zhang <quic_hazha@quicinc.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Link: https://lore.kernel.org/r/20230602084149.40031-4-quic_hazha@quicinc.com
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+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Coresight Dummy Trace Module
+=============================
+
+ :Author: Hao Zhang <quic_hazha@quicinc.com>
+ :Date: June 2023
+
+Introduction
+------------
+
+The Coresight dummy trace module is for the specific devices that kernel don't
+have permission to access or configure, e.g., CoreSight TPDMs on Qualcomm
+platforms. For these devices, a dummy driver is needed to register them as
+Coresight devices. The module may also be used to define components that may
+not have any programming interfaces, so that paths can be created in the driver.
+It provides Coresight API for operations on dummy devices, such as enabling and
+disabling them. It also provides the Coresight dummy sink/source paths for
+debugging.
+
+Config details
+--------------
+
+There are two types of nodes, dummy sink and dummy source. These nodes
+are available at ``/sys/bus/coresight/devices``.
+
+Example output::
+
+ $ ls -l /sys/bus/coresight/devices | grep dummy
+ dummy_sink0 -> ../../../devices/platform/soc@0/soc@0:sink/dummy_sink0
+ dummy_source0 -> ../../../devices/platform/soc@0/soc@0:source/dummy_source0