Commit 3b79104f authored by Hao Zhang's avatar Hao Zhang Committed by Suzuki K Poulose
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Documentation: trace: Add documentation for Coresight Dummy Trace 



Add documentation for Coresight Dummy Trace under trace/coresight.

Reviewed-by: default avatarBagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: default avatarHao Zhang <quic_hazha@quicinc.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230602084149.40031-4-quic_hazha@quicinc.com
parent 5911ff45

Documentation/trace/coresight/coresight-dummy.rst

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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