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Thu, 27 Feb 2020 07:14:32 -0800 (PST) From: Mike Leach To: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, linux-doc@vger.kernel.org Subject: [PATCH v5 6/6] coresight: docs: Add information about the topology representations Date: Thu, 27 Feb 2020 15:14:16 +0000 Message-Id: <20200227151416.14271-7-mike.leach@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200227151416.14271-1-mike.leach@linaro.org> References: <20200227151416.14271-1-mike.leach@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200227_071436_634868_6B9DF351 X-CRM114-Status: GOOD ( 15.76 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:333 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mike Leach , mathieu.poirier@linaro.org, suzuki.poulose@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Update the CoreSight documents to describe the new connections directory and the links between CoreSight devices in this directory. Signed-off-by: Mike Leach Reviewed-by: Mathieu Poirier --- .../trace/coresight/coresight-ect.rst | 5 +- Documentation/trace/coresight/coresight.rst | 85 +++++++++++++++++++ 2 files changed, 89 insertions(+), 1 deletion(-) 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 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 + cti_cpu0 -> ../../../23020000.cti/cti_cpu0 + nr_links + out:0 -> ../../../230c0000.funnel/funnel2 + +Following the out port to ``funnel2``:: + + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel2/connections + in:0 -> ../../../23040000.etm/etm0 + in:1 -> ../../../23140000.etm/etm3 + in:2 -> ../../../23240000.etm/etm4 + in:3 -> ../../../23340000.etm/etm5 + nr_links + out:0 -> ../../../20040000.funnel/funnel0 + +And again to ``funnel0``:: + + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel0/connections + in:0 -> ../../../220c0000.funnel/funnel1 + in:1 -> ../../../230c0000.funnel/funnel2 + nr_links + 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 + cti_sys0 -> ../../../20020000.cti/cti_sys0 + in:0 -> ../../../20040000.funnel/funnel0 + nr_links + out:0 -> ../../../20150000.funnel/funnel4 + +via ``funnel4``:: + + linaro-developer:~# ls -l /sys/bus/coresight/devices/funnel4/connections + in:0 -> ../../../20010000.etf/tmc_etf0 + in:1 -> ../../../20140000.etf/tmc_etf1 + nr_links + out:0 -> ../../../20120000.replicator/replicator0 + +and a ``replicator0``:: + + linaro-developer:~# ls -l /sys/bus/coresight/devices/replicator0/connections + in:0 -> ../../../20150000.funnel/funnel4 + nr_links + out:0 -> ../../../20030000.tpiu/tpiu0 + 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 + cti_sys0 -> ../../../20020000.cti/cti_sys0 + in:0 -> ../../../20120000.replicator/replicator0 + 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 + nr_links + stm0 -> ../../../20100000.stm/stm0 + tmc_etf0 -> ../../../20010000.etf/tmc_etf0 + tmc_etr0 -> ../../../20070000.etr/tmc_etr0 + tpiu0 -> ../../../20030000.tpiu/tpiu0 + + How to use the tracer modules -----------------------------