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Subject: Re: [PATCH v12 2/2] Documentation: Add document for UltraSoc SMB
 drivers
To:     Yicong Yang <yangyicong@huawei.com>, <mathieu.poirier@linaro.org>,
        <suzuki.poulose@arm.com>, <mike.leach@linaro.org>,
        <leo.yan@linaro.org>, <jonathan.cameron@huawei.com>,
        <john.garry@huawei.com>
References: <20221109135008.9485-1-hejunhao3@huawei.com>
 <20221109135008.9485-3-hejunhao3@huawei.com>
 <13e37836-b21c-662b-89b5-518fb091c612@huawei.com>
CC:     <yangyicong@hisilicon.com>, <coresight@lists.linaro.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <lpieralisi@kernel.org>,
        <linuxarm@huawei.com>, <liuqi115@huawei.com>,
        <f.fangjian@huawei.com>, <prime.zeng@hisilicon.com>
From:   hejunhao <hejunhao3@huawei.com>
Message-ID: <fedb61ff-13b5-ab5d-a394-d013b2bc0a6e@huawei.com>
Date:   Sat, 12 Nov 2022 18:06:24 +0800
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Hi Yicong.


On 2022/11/10 20:08, Yicong Yang wrote:
> On 2022/11/9 21:50, Junhao He wrote:
>> From: Qi Liu <liuqi115@huawei.com>
>>
>> This patch bring in documentation for UltraSoc SMB drivers.
>> It simply describes the device, sysfs interface and the
>> firmware bindings.
>>
>> Signed-off-by: Qi Liu <liuqi115@huawei.com>
>> Signed-off-by: Junhao He <hejunhao3@huawei.com>
>> ---
>>   .../sysfs-bus-coresight-devices-ultra_smb     | 31 +++++++
>>   .../trace/coresight/ultrasoc-smb.rst          | 80 +++++++++++++++++++
>>   2 files changed, 111 insertions(+)
>>   create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-ultra_smb
>>   create mode 100644 Documentation/trace/coresight/ultrasoc-smb.rst
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-ultra_smb b/Documentation/ABI/testing/sysfs-bus-coresight-devices-ultra_smb
>> new file mode 100644
>> index 000000000000..deaefd508105
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-ultra_smb
>> @@ -0,0 +1,31 @@
>> +What:		/sys/bus/coresight/devices/ultra_smb<N>/enable_sink
>> +Date:		November 2022
>> +KernelVersion:	6.2
>> +Contact:	Junhao He <hejunhao3@huawei.com>
>> +Description:	(RW) Add/remove a SMB device from a trace path. There can be
>> +		multiple sources for a single SMB device.
>> +
>> +What:		/sys/bus/coresight/devices/ultra_smb<N>/mgmt/buf_size
>> +Date:		November 2022
>> +KernelVersion:	6.2
>> +Contact:	Junhao He <hejunhao3@huawei.com>
>> +Description:	(Read) Shows the buffer size of each UltraSoc SMB device.
>> +
>> +What:		/sys/bus/coresight/devices/ultra_smb<N>/mgmt/buf_status
>> +Date:		November 2022
>> +KernelVersion:	6.2
>> +Contact:	Junhao He <hejunhao3@huawei.com>
>> +Description:	(Read) Shows the value held by UltraSoc SMB status register.
>> +		BIT(0) is zero means buffer is empty.
>> +
>> +What:		/sys/bus/coresight/devices/ultra_smb<N>/mgmt/read_pos
>> +Date:		November 2022
>> +KernelVersion:	6.2
>> +Contact:	Junhao He <hejunhao3@huawei.com>
>> +Description:	(Read) Shows the value held by UltraSoc SMB Read Pointer register.
>> +
>> +What:		/sys/bus/coresight/devices/ultra_smb<N>/mgmt/write_pos
>> +Date:		November 2022
>> +KernelVersion:	6.2
>> +Contact:	Junhao He <hejunhao3@huawei.com>
>> +Description:	(Read) Shows the value held by UltraSoc SMB Write Pointer register.
>> diff --git a/Documentation/trace/coresight/ultrasoc-smb.rst b/Documentation/trace/coresight/ultrasoc-smb.rst
>> new file mode 100644
>> index 000000000000..6d28ef0f6c88
>> --- /dev/null
>> +++ b/Documentation/trace/coresight/ultrasoc-smb.rst
>> @@ -0,0 +1,80 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +======================================
>> +UltraSoc - HW Assisted Tracing on SoC
>> +======================================
>> +   :Author:   Qi Liu <liuqi115@huawei.com>
>> +   :Date:     March 2022
>> +
>> +Introduction
>> +------------
>> +
>> +UltraSoc SMB is a per SCCL(Super CPU Cluster) hardware, and it provides a
>> +way to buffer and store CPU trace messages in a region of shared system
>> +memory. SMB is plugged as a coresight sink device and the corresponding
>> +trace generators (ETM) are plugged in as source devices.
>> +
>> +Sysfs files and directories
>> +---------------------------
>> +
>> +The SMB devices appear on the existing coresight bus alongside the other
>> +coresight devices::
>> +
>> +	$# ls /sys/bus/coresight/devices/
>> +	ultra_smb0   ultra_smb1   ultra_smb2   ultra_smb3
>> +
>> +The ``ultra_smb<N>`` named SMB associated with SCCL.::
>> +
>> +	$# ls /sys/bus/coresight/devices/ultra_smb0
>> +	enable_sink   mgmt
>> +	$# ls /sys/bus/coresight/devices/ultra_smb0/mgmt
>> +	buf_size  buf_status  read_pos  write_pos
>> +
>> +*Key file items are:-*
>> +   * ``read_pos``: Shows the value held by UltraSoc SMB Read Pointer register.
>> +   * ``write_pos``: Shows the value held by UltraSoc SMB Write Pointer register.
>> +   * ``buf_status``: Shows the value held by UltraSoc SMB status register.
>> +		     BIT(0) is zero means buffer is empty.
>> +   * ``buf_size``: Shows the buffer size of each UltraSoc SMB device.
>> +
>> +Firmware Bindings
>> +---------------------------
>> +
>> +SMB device is only supported with ACPI, and ACPI binding of SMB device
>> +describes SMB device indentifier, resource information and graph structure.
>> +
>> +SMB is identified by ACPI HID "HISI03A1", resource of device is declared using
>> +the _CRS method. Each SMB must present two base address, the first one is the
>> +configuration base address of SMB device, the second one is the base address of
>> +shared system memory.
>> +
>> +examples::
>> +
>> +    Device(USMB) {                                               \
>> +      Name(_HID, "HISI03A1")                                     \
>> +      Name(_CRS, ResourceTemplate() {                            \
>> +          MEM_RESRC(0x95100000, 0x951FFFFF, 0x100000)            \
>> +          MEM_RESRC(0x50000000, 0x53FFFFFF, 0x4000000)           \
> I cannot find MEM_RESRC in ACPI Spec 6.4, any references? If it's a self defined macro just expand it here.
>
> btw, you need to cc linux-doc@vger.kernel.org.
>
> Thanks.
"MEM_RESERVE" is a macro. will update the doc and add cc.
Thanks for the comments!

>> +      })                                                         \
>> +      Name(_DSD, Package() {                                     \
>> +        ToUUID("ab02a46b-74c7-45a2-bd68-f7d344ef2153"),          \
>> +	/* Use CoreSight Graph ACPI bindings to describe connections topology */
>> +        Package() {                                              \
>> +          0,                                                     \
>> +          1,                                                     \
>> +          Package() {                                            \
>> +            1,                                                   \
>> +            ToUUID("3ecbc8b6-1d0e-4fb3-8107-e627f805c6cd"),      \
>> +            8,                                                   \
>> +            Package() {0x8, 0, \_SB.S00.SL11.CL28.F008, 0},       \
>> +            Package() {0x9, 0, \_SB.S00.SL11.CL29.F009, 0},       \
>> +            Package() {0xa, 0, \_SB.S00.SL11.CL2A.F010, 0},       \
>> +            Package() {0xb, 0, \_SB.S00.SL11.CL2B.F011, 0},       \
>> +            Package() {0xc, 0, \_SB.S00.SL11.CL2C.F012, 0},       \
>> +            Package() {0xd, 0, \_SB.S00.SL11.CL2D.F013, 0},       \
>> +            Package() {0xe, 0, \_SB.S00.SL11.CL2E.F014, 0},       \
>> +            Package() {0xf, 0, \_SB.S00.SL11.CL2F.F015, 0},       \
>> +          }                                                      \
>> +        }                                                        \
>> +      })                                                         \
>> +    }
>>
> .
>
Best regards,
Junhao.