On Tue, Feb 11, 2020 at 10:58:08AM +0000, Mike Leach wrote: > Update the CoreSight documents to describe the new connections directory > and the links between CoreSight devices in this directory. > > Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx> > --- > .../trace/coresight/coresight-ect.rst | 5 +- > Documentation/trace/coresight/coresight.rst | 85 +++++++++++++++++++ > 2 files changed, 89 insertions(+), 1 deletion(-) > Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> > diff --git a/Documentation/trace/coresight/coresight-ect.rst b/Documentation/trace/coresight/coresight-ect.rst > index 067cee91c857..3539af895832 100644 > --- a/Documentation/trace/coresight/coresight-ect.rst > +++ b/Documentation/trace/coresight/coresight-ect.rst > @@ -71,7 +71,7 @@ capable of generating or using trigger signals.:: > > >$ ls /sys/bus/coresight/devices/etm0/cti_cpu0 > channels ctmid enable nr_trigger_cons mgmt power regs subsystem > - triggers0 triggers1 uevent > + connections triggers0 triggers1 uevent > > *Key file items are:-* > * ``enable``: enables/disables the CTI. > @@ -84,6 +84,9 @@ capable of generating or using trigger signals.:: > * ``channels``: Contains the channel API - CTI main programming interface. > * ``regs``: Gives access to the raw programmable CTI regs. > * ``mgmt``: the standard CoreSight management registers. > + * ``connections``: Links to connected *CoreSight* devices. The number of > + links can be 0 to ``nr_trigger_cons``. Actual number given by ``nr_links`` > + in this directory. > > > triggers<N> directories > diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst > index 108600ee1e12..0b73acb44efa 100644 > --- a/Documentation/trace/coresight/coresight.rst > +++ b/Documentation/trace/coresight/coresight.rst > @@ -241,6 +241,91 @@ to the newer scheme, to give a confirmation that what you see on your > system is not unexpected. One must use the "names" as they appear on > the system under specified locations. > > +Topology Representation > +----------------------- > + > +Each CoreSight component has a ``connections`` directory which will contain > +links to other CoreSight components. This allows the user to explore the trace > +topology and for larger systems, determine the most appropriate sink for a > +given source. The connection information can also be used to establish > +which CTI devices are connected to a given component. This directory contains a > +``nr_links`` attribute detailing the number of links in the directory. > + > +For an ETM source, in this case ``etm0`` on a Juno platform, a typical > +arrangement will be:: > + > + linaro-developer:~# ls - l /sys/bus/coresight/devices/etm0/connections > + <file details> cti_cpu0 -> ../../../23020000.cti/cti_cpu0 > + <file details> nr_links > + <file details> out:0 -> ../../../230c0000.funnel/funnel2 > + > +Following the out port to ``funnel2``:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel2/connections > + <file details> in:0 -> ../../../23040000.etm/etm0 > + <file details> in:1 -> ../../../23140000.etm/etm3 > + <file details> in:2 -> ../../../23240000.etm/etm4 > + <file details> in:3 -> ../../../23340000.etm/etm5 > + <file details> nr_links > + <file details> out:0 -> ../../../20040000.funnel/funnel0 > + > +And again to ``funnel0``:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel0/connections > + <file details> in:0 -> ../../../220c0000.funnel/funnel1 > + <file details> in:1 -> ../../../230c0000.funnel/funnel2 > + <file details> nr_links > + <file details> out:0 -> ../../../20010000.etf/tmc_etf0 > + > +Finding the first sink ``tmc_etf0``. This can be used to collect data > +as a sink, or as a link to propagate further along the chain:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/tmc_etf0/connections > + <file details> cti_sys0 -> ../../../20020000.cti/cti_sys0 > + <file details> in:0 -> ../../../20040000.funnel/funnel0 > + <file details> nr_links > + <file details> out:0 -> ../../../20150000.funnel/funnel4 > + > +via ``funnel4``:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel4/connections > + <file details> in:0 -> ../../../20010000.etf/tmc_etf0 > + <file details> in:1 -> ../../../20140000.etf/tmc_etf1 > + <file details> nr_links > + <file details> out:0 -> ../../../20120000.replicator/replicator0 > + > +and a ``replicator0``:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/replicator0/connections > + <file details> in:0 -> ../../../20150000.funnel/funnel4 > + <file details> nr_links > + <file details> out:0 -> ../../../20030000.tpiu/tpiu0 > + <file details> out:1 -> ../../../20070000.etr/tmc_etr0 > + > +Arriving at the final sink in the chain, ``tmc_etr0``:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/tmc_etr0/connections > + <file details> cti_sys0 -> ../../../20020000.cti/cti_sys0 > + <file details> in:0 -> ../../../20120000.replicator/replicator0 > + <file details> nr_links > + > +As described below, when using sysfs it is sufficient to enable a sink and > +a source for successful trace. The framework will correctly enable all > +intermediate links as required. > + > +Note: ``cti_sys0`` appears in two of the connections lists above. > +CTIs can connect to multiple devices and are arranged in a star topology > +via the CTM. See (:doc:`coresight-ect`) [#fourth]_ for further details. > +Looking at this device we see 4 connections:: > + > + linaro-developer:~# ls -l /sys/bus/coresight/devices/cti_sys0/connections > + <file details> nr_links > + <file details> stm0 -> ../../../20100000.stm/stm0 > + <file details> tmc_etf0 -> ../../../20010000.etf/tmc_etf0 > + <file details> tmc_etr0 -> ../../../20070000.etr/tmc_etr0 > + <file details> tpiu0 -> ../../../20030000.tpiu/tpiu0 > + > + > How to use the tracer modules > ----------------------------- > > -- > 2.17.1 >
