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Message-ID: <0aac4467-3abc-026c-4989-22b87bc80dc7@huawei.com>
Date: Thu, 24 Jun 2021 20:43:52 +0800
From: "liuqi (BA)" <liuqi115@...wei.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>,
Linuxarm <linuxarm@...wei.com>
CC: <alexander.shishkin@...ux.intel.com>, <suzuki.poulose@....com>,
<jonathan.zhouwen@...wei.com>, <f.fangjian@...wei.com>,
<linux-kernel@...r.kernel.org>, <coresight@...ts.linaro.org>
Subject: Re: [RFC PATCH 1/4] Documentation: tracing: Documentation for
ultrasoc framework and drivers
Hi Mathieu,
Thanks for reviewing this patch.
On 2021/6/24 6:51, Mathieu Poirier wrote:
> Hi,
>
> On Tue, Jun 15, 2021 at 05:34:41PM +0800, Qi Liu wrote:
>> Ultrasoc trace module is a system level solution for both core tracing
>> and SoC tracing. This patch brings in a documentation for ultrasoc
>> framework and drivers. It simply introduces function of ultrasoc, a
>> typical Ultrasoc system, and a driver framework for ultrasoc.
>>
>> Signed-off-by: Jonathan Zhou <jonathan.zhouwen@...wei.com>
>> Signed-off-by: Qi Liu <liuqi115@...wei.com>
>> ---
>> Documentation/trace/ultrasoc-trace.rst | 209 +++++++++++++++++++++++++++++++++
>> 1 file changed, 209 insertions(+)
>> create mode 100644 Documentation/trace/ultrasoc-trace.rst
>>
>> diff --git a/Documentation/trace/ultrasoc-trace.rst b/Documentation/trace/ultrasoc-trace.rst
>> new file mode 100644
>> index 0000000..36d2df2
>> --- /dev/null
>> +++ b/Documentation/trace/ultrasoc-trace.rst
>> @@ -0,0 +1,209 @@
>> +=======================================================
>> +Siemens Embedded Analytics - HW Assisted Tracing on SoC
>> +=======================================================
>> + :Author: Jonathan Zhou <Jonathan.zhouwen@...wei.com>
>> + Qi Liu <liuqi115@...wei.com>
>> + :Date: January 16th, 2021
>> +
>> +Introduction
>> +------------
>> +
>> +The Siemens Embedded Analytics Framework is system level solution for tracing
>> +of multiple type SoC, this document is concerned with trace module. This module
>> +has two main components: AXI Bus Communicator and System Memory Buffer.
>> +
>> +The AXI Communicator has upstream and downstream channels, the upstream channel
>> +is used to transmit user configuration, and downstream channel to carry response
>> +and trace data to the users.
>> +
>> +The System Memory Buffer 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 @ | @ AXI COM @ JTAG
>> + @@@@@ |--> @@@@@@@@@
>> + @@@--| @@@@@@@
>> + @ | @@@@@
>> + | |
>> + | |
>> + * *
>> + ***************************************************************
>> + **************************** AMBA AXI ****************************
>> + *****************************************************************
>> +
>> +Acronyms
>> +---------------------------
>> +
>> +Acronyms:
>> +
>> +AXI-COM: AXI Communicator
>> +SMB: System Memory Buffer
>> +TRC: Trace receiver
>> +
>> +Framework and implementation
>> +------------------------------
>> +
>> +Siemens Embedded Analytics Framework is implemented as a platform device. The
>> +platform device provides a global point to configure the Embedded Analytics
>> +subsystem, and also provides a ``struct ultrasoc_com`` to manage AXI-COM and
>> +SMB.
>> +
>> +AXI-COM and SMB are implemented as platform devices, each SCCL has one AXI-COM
>> +device and one SMB device. AXI-COM and SMB can use the following API to register
>> +into Embedded Analytics framework:
>> +.. c:function:: struct ultrasoc_com *ultrasoc_register_com(struct device *root_dev, struct ultrasoc_com_descp *com_descp)
>> +.. c:function:: void ultrasoc_unregister_com(struct ultrasoc_com *com);
>> +
>> +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->System Memory.
>> +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.Embedded Analytics>:00 <HID.axi-com>:00 <HID.smb>:00
>> + $# ls /sys/bus/platform/devices/<HID.Embedded Analytics>:00
>> + com_mux firmware_node power <HID.axi-com>:00
>> + driver message subsystem <HID.smb>:00
>> + driver_override modalias uevent
>> + $# 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::
>
> I haven't looked at the rest of the patchset but unless you have changed that,
> only one sink will be selected by the framework when operating from sysfs.
> Regardless of the number of sinks that were enabled, the framework will pick the
> first one it finds.
>
Yes, framework only choose the first sink device if there are several
sinks. I'll change the description in document in next version, thanks.
>> +
>> + $# 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/@...k_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
>
> After reading all this and without looking at the rest of the patchset it seems
> to me this work should go under drivers/hwtracing/coresight/.
>
So how about drivers/hwtracing/coresight/ultrasoc?
> There is a lot of code to review and as such it will take me a fair amount of
> time to go through it all. Comments will be scattered over several days (weeks)
> - I will set you know when I am done.
>
> Thanks,
> Mathieu
Ok, thanks for revewing this patchset
Qi
>
>> --
>> 2.7.4
>>
> .
>
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