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. 21*3b79104fSHao Zhang 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``. 27*3b79104fSHao Zhang 28*3b79104fSHao ZhangExample output:: 29*3b79104fSHao Zhang 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 33