1*3b79104fSHao Zhang.. SPDX-License-Identifier: GPL-2.0
2*3b79104fSHao Zhang
3*3b79104fSHao Zhang=============================
4*3b79104fSHao ZhangCoresight Dummy Trace Module
5*3b79104fSHao Zhang=============================
6*3b79104fSHao Zhang
7*3b79104fSHao Zhang    :Author:   Hao Zhang <quic_hazha@quicinc.com>
8*3b79104fSHao Zhang    :Date:     June 2023
9*3b79104fSHao Zhang
10*3b79104fSHao ZhangIntroduction
11*3b79104fSHao Zhang------------
12*3b79104fSHao Zhang
13*3b79104fSHao ZhangThe Coresight dummy trace module is for the specific devices that kernel don't
14*3b79104fSHao Zhanghave permission to access or configure, e.g., CoreSight TPDMs on Qualcomm
15*3b79104fSHao Zhangplatforms. For these devices, a dummy driver is needed to register them as
16*3b79104fSHao ZhangCoresight devices. The module may also be used to define components that may
17*3b79104fSHao Zhangnot have any programming interfaces, so that paths can be created in the driver.
18*3b79104fSHao ZhangIt provides Coresight API for operations on dummy devices, such as enabling and
19*3b79104fSHao Zhangdisabling them. It also provides the Coresight dummy sink/source paths for
20*3b79104fSHao Zhangdebugging.
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22*3b79104fSHao ZhangConfig details
23*3b79104fSHao Zhang--------------
24*3b79104fSHao Zhang
25*3b79104fSHao ZhangThere are two types of nodes, dummy sink and dummy source. These nodes
26*3b79104fSHao Zhangare available at ``/sys/bus/coresight/devices``.
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28*3b79104fSHao ZhangExample output::
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30*3b79104fSHao Zhang    $ ls -l /sys/bus/coresight/devices | grep dummy
31*3b79104fSHao Zhang    dummy_sink0 -> ../../../devices/platform/soc@0/soc@0:sink/dummy_sink0
32*3b79104fSHao Zhang    dummy_source0 -> ../../../devices/platform/soc@0/soc@0:source/dummy_source0
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