1.. SPDX-License-Identifier: GPL-2.0
2
3=============================
4Coresight Dummy Trace Module
5=============================
6
7    :Author:   Hao Zhang <quic_hazha@quicinc.com>
8    :Date:     June 2023
9
10Introduction
11------------
12
13The Coresight dummy trace module is for the specific devices that kernel don't
14have permission to access or configure, e.g., CoreSight TPDMs on Qualcomm
15platforms. For these devices, a dummy driver is needed to register them as
16Coresight devices. The module may also be used to define components that may
17not have any programming interfaces, so that paths can be created in the driver.
18It provides Coresight API for operations on dummy devices, such as enabling and
19disabling them. It also provides the Coresight dummy sink/source paths for
20debugging.
21
22Config details
23--------------
24
25There are two types of nodes, dummy sink and dummy source. These nodes
26are available at ``/sys/bus/coresight/devices``.
27
28Example output::
29
30    $ ls -l /sys/bus/coresight/devices | grep dummy
31    dummy_sink0 -> ../../../devices/platform/soc@0/soc@0:sink/dummy_sink0
32    dummy_source0 -> ../../../devices/platform/soc@0/soc@0:source/dummy_source0
33