Messages in this thread | | | Date | Mon, 6 Sep 2021 11:34:46 -0600 | From | Mathieu Poirier <> | Subject | Re: [PATCH 1/2] Documentation: tracing: Documentation for ultrasoc SMB drivers |
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On Mon, Jul 19, 2021 at 07:17:36PM +0800, Qi Liu wrote: > Ultrasoc trace module is a system level solution for tracing, and SMB > is the component in trace module to store trace message. This patch > brings in a documentation for ultrasoc SMB driver and simple introduces > how to use ultrasoc SMB by sysfs interface and perf interface. > > Signed-off-by: Qi Liu <liuqi115@huawei.com> > --- > .../trace/coresight/ultrasoc-trace.rst | 193 ++++++++++++++++++ > 1 file changed, 193 insertions(+) > create mode 100644 Documentation/trace/coresight/ultrasoc-trace.rst > > diff --git a/Documentation/trace/coresight/ultrasoc-trace.rst b/Documentation/trace/coresight/ultrasoc-trace.rst > new file mode 100644 > index 000000000000..dee133e27bf3 > --- /dev/null > +++ b/Documentation/trace/coresight/ultrasoc-trace.rst > @@ -0,0 +1,193 @@ > +======================================================= > +Siemens Embedded Analytics - HW Assisted Tracing on SoC > +======================================================= > + :Author: Jonathan Zhou <Jonathan.zhouwen@huawei.com> > + Qi Liu <liuqi115@huawei.com> > + :Date: July 8th, 2021 > + > +Introduction > +------------ > + > +This document is concerned with the Siemens Embedded Analytics Framework, > +using for tracing of multiple type SoC. As this module is developed by > +Ultrasoc technology, which is acquired by Siemens, we still use "Ultrasoc" > +to name document and structures. > + > +System Memory Buffer is an important component in this Analytics Framework, > +it provides a way to buffer and store messages in system memory. It provides > +a capability to store messages received on its input message interface to an > +area of system memory. > + > +A typical Siemens trace system would look like the following diagram: > + @@@@@@@@@@@@@ > + @ CPU @ > + @@@@@@@@@@@@@ > + ############# > + # Coresight # > + # ETM # > + ####### > + ### > + # > + | > + * > + ******************************* > + *** AMBA Advanced Trace Bus (ATB) *** > + ***************^*************** > + =============== | > + === FUNNEL ==<--- | > + ======= > + | > + * > + @@@@@@@ > + @ TRC @ > + @@@@@ > + @@@ > + @ > + | > + * > + ************************************** ******************* > + ************************ Message BUS *************************** > + ******************^************************^**************** > + | | > + @@@@@@@@@@@@@@@@@@ | @@@@@@@@@@@@ > + @ Message Engine @ | @ JTAG COM @ > + @@@@@@@@@@@@@@@@@@ | @@@@@@@@@@ > + | |---> @@@@@@@@ > + | @@@@@@ > + @@@@@@@ | > + @ SMB @ JTAG > + @@@@@ > + @@@ > + @ > + | > + | > + * > + *************************************************************** > + **************************** AMBA AXI **************************** > + ***************************************************************** > + > +Acronyms > +--------------------------- > + > +Acronyms: > + > +SMB: System Memory Buffer > +TRC: Trace receiver > + > +Framework and implementation > +------------------------------ > + > +SMB is implemented as platform device, each SCCL has one SMB device. > + > +As TRC receives data from coresight ETM device, SMB can use the following API > +to register into coresight framework as a sink device: > +.. c:function:: struct coresight_device *coresight_register(struct coresight_desc *desc); > +.. c:function:: void coresight_unregister(struct coresight_device *csdev); > + > +Then users can get trace data by this path: ETM->funnel->SMB. > +More information about coresight framework can be found in > +Documention/trace/coresight/coresight.rst. > + > +If everything goes well, the relationship of Embedded Analytics devices will be > +described under the sysfs:: > + > + $# ls /sys/bus/platform/devices/ > + <HID.smb>:00 > + $# ls /sys/bus/coresight/devices/ > + etm0 etm14 etm2 etm25 etm30 etm8 funnel4 > + etm1 etm15 etm20 etm26 etm31 etm9 funnel5 > + etm10 etm16 etm21 etm27 etm4 funnel0 funnel6 > + etm11 etm17 etm22 etm28 etm5 funnel1 funnel7 > + etm12 etm18 etm23 etm29 etm6 funnel2 sink_smb0 > + etm13 etm19 etm24 etm3 etm7 funnel3 > + $# ls -l /sys/bus/coresight/devices/funnel0/connections/ > + <file details> in:0 -> ../../../../system/cpu/cpu0/ARMHC500:00/etm0 > + <file details> in:1 -> ../../../../system/cpu/cpu1/ARMHC500:01/etm1 > + <file details> in:2 -> ../../../../system/cpu/cpu2/ARMHC500:02/etm2 > + <file details> in:3 -> ../../../../system/cpu/cpu3/ARMHC500:03/etm3 > + <file details> nr_links > + <file details> out:0 -> ../../../HISI0391:00/HISI03A1:00/sink_smb0 > + $# ls -l /sys/bus/coresight/devices/sink_smb0/connections/ > + <file details> in:101 -> ../../../../ARMHC9FE:05/funnel5 > + <file details> in:114 -> ../../../../ARMHC9FE:07/funnel7 > + <file details> in:121 -> ../../../../ARMHC9FE:03/funnel3 > + <file details> in:39 -> ../../../../ARMHC9FE:00/funnel0 > + <file details> in:51 -> ../../../../ARMHC9FE:04/funnel4 > + <file details> in:61 -> ../../../../ARMHC9FE:06/funnel6 > + <file details> in:68 -> ../../../../ARMHC9FE:02/funnel2 > + <file details> in:89 -> ../../../../ARMHC9FE:01/funnel1 > + <file details> nr_links > + > +How to use the Embedded Analytics trace module > +----------------------------------------------- > + > +There are two ways to use the Embedded Analytics trace module: > + > +1. interacting directly with the devices using the sysFS interface. > +2. using the perf cmd line tools. > + > +1) Using the sysFS interface: > + > +Before trace collection can start, a coresight sink needs to be identified. > +There is no limit on the amount of sinks (nor sources) that can be enabled at > +any given moment. As a generic operation, all device pertaining to the sink > +class will have an "active" entry in sysfs:: > + > + $# ls /sys/bus/coresight/devices/ > + etm0 etm14 etm2 etm25 etm30 etm8 funnel4 > + etm1 etm15 etm20 etm26 etm31 etm9 funnel5 > + etm10 etm16 etm21 etm27 etm4 funnel0 funnel6 > + etm11 etm17 etm22 etm28 etm5 funnel1 funnel7 > + etm12 etm18 etm23 etm29 etm6 funnel2 sink_smb0 > + etm13 etm19 etm24 etm3 etm7 funnel3 > + $# ls /sys/bus/coresight/devices/sink_smb0 > + connections enable_sink firmware_node power subsystem uevent > + $# echo 1 > /sys/bus/coresight/devices/sink_smb0/enable_sink > + $# cat /sys/bus/coresight/devices/sink_smb0/enable_sink > + 1 > + > +When start trace collection, etm devices corresponding to the enabled sink > +should be selected:: > + > + $# echo 1 > /sys/bus/coresight/devices/etm0/enable_source > + $# cat /sys/bus/coresight/devices/etm0/enable_source > + 1 > + $# cat /sys/bus/platform/devices/<HID.smb>:00/com_status > + com-type : DOWN-ONLY > + service status : stopped > + interrupt status : 0x00000003 > + write point : 0x5437f400 <----- The write pointer is moving > + > +Trace collection is stopped the same way:: > + > + $# echo 0 > /sys/bus/coresight/devices/etm0/enable_source > + $# echo 0 > /sys/bus/coresight/devices/sink_smb0/enable_sink > + > +The content of the SMB buffer can be harvested directly from /dev:: > + > + $# dd if=/dev/sink_smb0 of=~/cstrace.bin > + 5233+0 records in > + 5233+0 records out > + 2679296 bytes (2.7 MB) copied, 0.0131708 s, 203 MB/s > + > + root:/sys/bus/coresight/devices# > + > +The file cstrace.bin can be decompressed using "ptm2human". > + > +2) Using perf framework: > + > +As SMB device has been registered with coresight framework, perf tool can be > +used to control Embedded Analytics trace collection, and the method is similar > +to using perf to do coresight trace collection. > + > +The only thing to note is, list of cpus should be correspond to the specified > +sink device. > + > +Example usage of perf:: > + > + $# ./perf list pmu > + cs_etm// [Kernel PMU event] > + $# ./perf record -e cs_etm/@sink_smb0/ -C 0 --per-thread sleep 2s > + [ perf record: Woken up 2 times to write data ] > + [ perf record: Captured and wrote 0.288 MB perf.data ] > + $# ./perf report
This IP block works like any other sink device and as such I don't really see a need for this documentation - especially since it is mostly conveying the same information already present in coresight.rst.
Thanks, Mathieu
> -- > 2.17.1 >
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