[13/14] docs: hwmon: Document PECI drivers

Commit Message

Winiarska, Iwona July 12, 2021, 10:04 p.m. UTC

From: Jae Hyun Yoo <[e-mail]>

Add documentation for peci-cputemp driver that provides DTS thermal
readings for CPU packages and CPU cores and peci-dimmtemp driver that
provides DTS thermal readings for DIMMs.

Signed-off-by: Jae Hyun Yoo <[e-mail]>
Co-developed-by: Iwona Winiarska <[e-mail]>
Signed-off-by: Iwona Winiarska <[e-mail]>
Reviewed-by: Pierre-Louis Bossart <[e-mail]>
---
 Documentation/hwmon/index.rst         |  2 +
 Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
 Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
 MAINTAINERS                           |  2 +
 4 files changed, 155 insertions(+)
 create mode 100644 Documentation/hwmon/peci-cputemp.rst
 create mode 100644 Documentation/hwmon/peci-dimmtemp.rst

Comments

Zev Weiss July 27, 2021, 10:58 p.m. UTC | #1

On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
>From: Jae Hyun Yoo <[e-mail]>
>
>Add documentation for peci-cputemp driver that provides DTS thermal
>readings for CPU packages and CPU cores and peci-dimmtemp driver that
>provides DTS thermal readings for DIMMs.
>
>Signed-off-by: Jae Hyun Yoo <[e-mail]>
>Co-developed-by: Iwona Winiarska <[e-mail]>
>Signed-off-by: Iwona Winiarska <[e-mail]>
>Reviewed-by: Pierre-Louis Bossart <[e-mail]>
>---
> Documentation/hwmon/index.rst         |  2 +
> Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
> Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
> MAINTAINERS                           |  2 +
> 4 files changed, 155 insertions(+)
> create mode 100644 Documentation/hwmon/peci-cputemp.rst
> create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
>
>diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
>index bc01601ea81a..cc76b5b3f791 100644
>--- a/Documentation/hwmon/index.rst
>+++ b/Documentation/hwmon/index.rst
>@@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
>    pcf8591
>    pim4328
>    pm6764tr
>+   peci-cputemp
>+   peci-dimmtemp
>    pmbus
>    powr1220
>    pxe1610
>diff --git a/Documentation/hwmon/peci-cputemp.rst b/Documentation/hwmon/peci-cputemp.rst
>new file mode 100644
>index 000000000000..d3a218ba810a
>--- /dev/null
>+++ b/Documentation/hwmon/peci-cputemp.rst
>@@ -0,0 +1,93 @@
>+.. SPDX-License-Identifier: GPL-2.0-only
>+
>+Kernel driver peci-cputemp
>+==========================
>+
>+Supported chips:
>+	One of Intel server CPUs listed below which is connected to a PECI bus.
>+		* Intel Xeon E5/E7 v3 server processors
>+			Intel Xeon E5-14xx v3 family
>+			Intel Xeon E5-24xx v3 family
>+			Intel Xeon E5-16xx v3 family
>+			Intel Xeon E5-26xx v3 family
>+			Intel Xeon E5-46xx v3 family
>+			Intel Xeon E7-48xx v3 family
>+			Intel Xeon E7-88xx v3 family
>+		* Intel Xeon E5/E7 v4 server processors
>+			Intel Xeon E5-16xx v4 family
>+			Intel Xeon E5-26xx v4 family
>+			Intel Xeon E5-46xx v4 family
>+			Intel Xeon E7-48xx v4 family
>+			Intel Xeon E7-88xx v4 family
>+		* Intel Xeon Scalable server processors
>+			Intel Xeon D family
>+			Intel Xeon Bronze family
>+			Intel Xeon Silver family
>+			Intel Xeon Gold family
>+			Intel Xeon Platinum family
>+
>+	Datasheet: Available from http://www.intel.com/design/literature.htm
>+
>+Author: Jae Hyun Yoo <[e-mail]>
>+
>+Description
>+-----------
>+
>+This driver implements a generic PECI hwmon feature which provides Digital
>+Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that are
>+accessible via the processor PECI interface.
>+
>+All temperature values are given in millidegree Celsius and will be measurable
>+only when the target CPU is powered on.
>+
>+Sysfs interface
>+-------------------
>+
>+======================= =======================================================
>+temp1_label		"Die"
>+temp1_input		Provides current die temperature of the CPU package.
>+temp1_max		Provides thermal control temperature of the CPU package
>+			which is also known as Tcontrol.
>+temp1_crit		Provides shutdown temperature of the CPU package which
>+			is also known as the maximum processor junction
>+			temperature, Tjmax or Tprochot.
>+temp1_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
>+			the CPU package.
>+
>+temp2_label		"DTS"
>+temp2_input		Provides current DTS temperature of the CPU package.

Would this be a good place to note the slightly counter-intuitive nature
of DTS readings?  i.e. add something along the lines of "The DTS sensor
produces a delta relative to Tjmax, so negative values are normal and
values approaching zero are hot."  (In my experience people who aren't
already familiar with it tend to think something's wrong when a CPU
temperature reading shows -50C.)

>+temp2_max		Provides thermal control temperature of the CPU package
>+			which is also known as Tcontrol.
>+temp2_crit		Provides shutdown temperature of the CPU package which
>+			is also known as the maximum processor junction
>+			temperature, Tjmax or Tprochot.
>+temp2_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
>+			the CPU package.
>+
>+temp3_label		"Tcontrol"
>+temp3_input		Provides current Tcontrol temperature of the CPU
>+			package which is also known as Fan Temperature target.
>+			Indicates the relative value from thermal monitor trip
>+			temperature at which fans should be engaged.
>+temp3_crit		Provides Tcontrol critical value of the CPU package
>+			which is same to Tjmax.
>+
>+temp4_label		"Tthrottle"
>+temp4_input		Provides current Tthrottle temperature of the CPU
>+			package. Used for throttling temperature. If this value
>+			is allowed and lower than Tjmax - the throttle will
>+			occur and reported at lower than Tjmax.
>+
>+temp5_label		"Tjmax"
>+temp5_input		Provides the maximum junction temperature, Tjmax of the
>+			CPU package.
>+
>+temp[6-N]_label		Provides string "Core X", where X is resolved core
>+			number.
>+temp[6-N]_input		Provides current temperature of each core.
>+temp[6-N]_max		Provides thermal control temperature of the core.
>+temp[6-N]_crit		Provides shutdown temperature of the core.
>+temp[6-N]_crit_hyst	Provides the hysteresis value from Tcontrol to Tjmax of
>+			the core.

I only see *_label and *_input for the per-core temperature sensors, no
*_max, *_crit, or *_crit_hyst.

>+
>+======================= =======================================================
>diff --git a/Documentation/hwmon/peci-dimmtemp.rst b/Documentation/hwmon/peci-dimmtemp.rst
>new file mode 100644
>index 000000000000..1778d9317e43
>--- /dev/null
>+++ b/Documentation/hwmon/peci-dimmtemp.rst
>@@ -0,0 +1,58 @@
>+.. SPDX-License-Identifier: GPL-2.0
>+
>+Kernel driver peci-dimmtemp
>+===========================
>+
>+Supported chips:
>+	One of Intel server CPUs listed below which is connected to a PECI bus.
>+		* Intel Xeon E5/E7 v3 server processors
>+			Intel Xeon E5-14xx v3 family
>+			Intel Xeon E5-24xx v3 family
>+			Intel Xeon E5-16xx v3 family
>+			Intel Xeon E5-26xx v3 family
>+			Intel Xeon E5-46xx v3 family
>+			Intel Xeon E7-48xx v3 family
>+			Intel Xeon E7-88xx v3 family
>+		* Intel Xeon E5/E7 v4 server processors
>+			Intel Xeon E5-16xx v4 family
>+			Intel Xeon E5-26xx v4 family
>+			Intel Xeon E5-46xx v4 family
>+			Intel Xeon E7-48xx v4 family
>+			Intel Xeon E7-88xx v4 family
>+		* Intel Xeon Scalable server processors
>+			Intel Xeon D family
>+			Intel Xeon Bronze family
>+			Intel Xeon Silver family
>+			Intel Xeon Gold family
>+			Intel Xeon Platinum family
>+
>+	Datasheet: Available from http://www.intel.com/design/literature.htm
>+
>+Author: Jae Hyun Yoo <[e-mail]>
>+
>+Description
>+-----------
>+
>+This driver implements a generic PECI hwmon feature which provides Digital
>+Thermal Sensor (DTS) thermal readings of DIMM components that are accessible
>+via the processor PECI interface.

I had thought "DTS" referred to a fairly specific sensor in the CPU; is
the same term also used for DIMM temp sensors or is the mention of it
here a copy/paste error?

>+
>+All temperature values are given in millidegree Celsius and will be measurable
>+only when the target CPU is powered on.
>+
>+Sysfs interface
>+-------------------
>+
>+======================= =======================================================
>+
>+temp[N]_label		Provides string "DIMM CI", where C is DIMM channel and
>+			I is DIMM index of the populated DIMM.
>+temp[N]_input		Provides current temperature of the populated DIMM.
>+temp[N]_max		Provides thermal control temperature of the DIMM.
>+temp[N]_crit		Provides shutdown temperature of the DIMM.
>+
>+======================= =======================================================
>+
>+Note:
>+	DIMM temperature attributes will appear when the client CPU's BIOS
>+	completes memory training and testing.
>diff --git a/MAINTAINERS b/MAINTAINERS
>index 35ba9e3646bd..d16da127bbdc 100644
>--- a/MAINTAINERS
>+++ b/MAINTAINERS
>@@ -14509,6 +14509,8 @@ M:	Iwona Winiarska <[e-mail]>
> R:	Jae Hyun Yoo <[e-mail]>
> L:	[e-mail]
> S:	Supported
>+F:	Documentation/hwmon/peci-cputemp.rst
>+F:	Documentation/hwmon/peci-dimmtemp.rst
> F:	drivers/hwmon/peci/
>
> PECI SUBSYSTEM
>-- 
>2.31.1
>

Guenter Roeck July 28, 2021, 12:49 a.m. UTC | #2

On 7/27/21 3:58 PM, Zev Weiss wrote:
> On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
>> From: Jae Hyun Yoo <[e-mail]>
>>
>> Add documentation for peci-cputemp driver that provides DTS thermal
>> readings for CPU packages and CPU cores and peci-dimmtemp driver that
>> provides DTS thermal readings for DIMMs.
>>
>> Signed-off-by: Jae Hyun Yoo <[e-mail]>
>> Co-developed-by: Iwona Winiarska <[e-mail]>
>> Signed-off-by: Iwona Winiarska <[e-mail]>
>> Reviewed-by: Pierre-Louis Bossart <[e-mail]>
>> ---
>> Documentation/hwmon/index.rst         |  2 +
>> Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
>> Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
>> MAINTAINERS                           |  2 +
>> 4 files changed, 155 insertions(+)
>> create mode 100644 Documentation/hwmon/peci-cputemp.rst
>> create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
>>
>> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
>> index bc01601ea81a..cc76b5b3f791 100644
>> --- a/Documentation/hwmon/index.rst
>> +++ b/Documentation/hwmon/index.rst
>> @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
>>     pcf8591
>>     pim4328
>>     pm6764tr
>> +   peci-cputemp
>> +   peci-dimmtemp
>>     pmbus
>>     powr1220
>>     pxe1610
>> diff --git a/Documentation/hwmon/peci-cputemp.rst b/Documentation/hwmon/peci-cputemp.rst
>> new file mode 100644
>> index 000000000000..d3a218ba810a
>> --- /dev/null
>> +++ b/Documentation/hwmon/peci-cputemp.rst
>> @@ -0,0 +1,93 @@
>> +.. SPDX-License-Identifier: GPL-2.0-only
>> +
>> +Kernel driver peci-cputemp
>> +==========================
>> +
>> +Supported chips:
>> +	One of Intel server CPUs listed below which is connected to a PECI bus.
>> +		* Intel Xeon E5/E7 v3 server processors
>> +			Intel Xeon E5-14xx v3 family
>> +			Intel Xeon E5-24xx v3 family
>> +			Intel Xeon E5-16xx v3 family
>> +			Intel Xeon E5-26xx v3 family
>> +			Intel Xeon E5-46xx v3 family
>> +			Intel Xeon E7-48xx v3 family
>> +			Intel Xeon E7-88xx v3 family
>> +		* Intel Xeon E5/E7 v4 server processors
>> +			Intel Xeon E5-16xx v4 family
>> +			Intel Xeon E5-26xx v4 family
>> +			Intel Xeon E5-46xx v4 family
>> +			Intel Xeon E7-48xx v4 family
>> +			Intel Xeon E7-88xx v4 family
>> +		* Intel Xeon Scalable server processors
>> +			Intel Xeon D family
>> +			Intel Xeon Bronze family
>> +			Intel Xeon Silver family
>> +			Intel Xeon Gold family
>> +			Intel Xeon Platinum family
>> +
>> +	Datasheet: Available from http://www.intel.com/design/literature.htm
>> +
>> +Author: Jae Hyun Yoo <[e-mail]>
>> +
>> +Description
>> +-----------
>> +
>> +This driver implements a generic PECI hwmon feature which provides Digital
>> +Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that are
>> +accessible via the processor PECI interface.
>> +
>> +All temperature values are given in millidegree Celsius and will be measurable
>> +only when the target CPU is powered on.
>> +
>> +Sysfs interface
>> +-------------------
>> +
>> +======================= =======================================================
>> +temp1_label		"Die"
>> +temp1_input		Provides current die temperature of the CPU package.
>> +temp1_max		Provides thermal control temperature of the CPU package
>> +			which is also known as Tcontrol.
>> +temp1_crit		Provides shutdown temperature of the CPU package which
>> +			is also known as the maximum processor junction
>> +			temperature, Tjmax or Tprochot.
>> +temp1_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
>> +			the CPU package.
>> +
>> +temp2_label		"DTS"
>> +temp2_input		Provides current DTS temperature of the CPU package.
> 
> Would this be a good place to note the slightly counter-intuitive nature
> of DTS readings?  i.e. add something along the lines of "The DTS sensor
> produces a delta relative to Tjmax, so negative values are normal and
> values approaching zero are hot."  (In my experience people who aren't
> already familiar with it tend to think something's wrong when a CPU
> temperature reading shows -50C.)
> 

All attributes shall follow the ABI, and the driver must translate reported
values to degrees C. If those sensors do not follow the ABI and report something
else, I won't accept the driver.

Guenter

>> +temp2_max		Provides thermal control temperature of the CPU package
>> +			which is also known as Tcontrol.
>> +temp2_crit		Provides shutdown temperature of the CPU package which
>> +			is also known as the maximum processor junction
>> +			temperature, Tjmax or Tprochot.
>> +temp2_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
>> +			the CPU package.
>> +
>> +temp3_label		"Tcontrol"
>> +temp3_input		Provides current Tcontrol temperature of the CPU
>> +			package which is also known as Fan Temperature target.
>> +			Indicates the relative value from thermal monitor trip
>> +			temperature at which fans should be engaged.
>> +temp3_crit		Provides Tcontrol critical value of the CPU package
>> +			which is same to Tjmax.
>> +
>> +temp4_label		"Tthrottle"
>> +temp4_input		Provides current Tthrottle temperature of the CPU
>> +			package. Used for throttling temperature. If this value
>> +			is allowed and lower than Tjmax - the throttle will
>> +			occur and reported at lower than Tjmax.
>> +
>> +temp5_label		"Tjmax"
>> +temp5_input		Provides the maximum junction temperature, Tjmax of the
>> +			CPU package.
>> +
>> +temp[6-N]_label		Provides string "Core X", where X is resolved core
>> +			number.
>> +temp[6-N]_input		Provides current temperature of each core.
>> +temp[6-N]_max		Provides thermal control temperature of the core.
>> +temp[6-N]_crit		Provides shutdown temperature of the core.
>> +temp[6-N]_crit_hyst	Provides the hysteresis value from Tcontrol to Tjmax of
>> +			the core.
> 
> I only see *_label and *_input for the per-core temperature sensors, no
> *_max, *_crit, or *_crit_hyst.
> 
>> +
>> +======================= =======================================================
>> diff --git a/Documentation/hwmon/peci-dimmtemp.rst b/Documentation/hwmon/peci-dimmtemp.rst
>> new file mode 100644
>> index 000000000000..1778d9317e43
>> --- /dev/null
>> +++ b/Documentation/hwmon/peci-dimmtemp.rst
>> @@ -0,0 +1,58 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +Kernel driver peci-dimmtemp
>> +===========================
>> +
>> +Supported chips:
>> +	One of Intel server CPUs listed below which is connected to a PECI bus.
>> +		* Intel Xeon E5/E7 v3 server processors
>> +			Intel Xeon E5-14xx v3 family
>> +			Intel Xeon E5-24xx v3 family
>> +			Intel Xeon E5-16xx v3 family
>> +			Intel Xeon E5-26xx v3 family
>> +			Intel Xeon E5-46xx v3 family
>> +			Intel Xeon E7-48xx v3 family
>> +			Intel Xeon E7-88xx v3 family
>> +		* Intel Xeon E5/E7 v4 server processors
>> +			Intel Xeon E5-16xx v4 family
>> +			Intel Xeon E5-26xx v4 family
>> +			Intel Xeon E5-46xx v4 family
>> +			Intel Xeon E7-48xx v4 family
>> +			Intel Xeon E7-88xx v4 family
>> +		* Intel Xeon Scalable server processors
>> +			Intel Xeon D family
>> +			Intel Xeon Bronze family
>> +			Intel Xeon Silver family
>> +			Intel Xeon Gold family
>> +			Intel Xeon Platinum family
>> +
>> +	Datasheet: Available from http://www.intel.com/design/literature.htm
>> +
>> +Author: Jae Hyun Yoo <[e-mail]>
>> +
>> +Description
>> +-----------
>> +
>> +This driver implements a generic PECI hwmon feature which provides Digital
>> +Thermal Sensor (DTS) thermal readings of DIMM components that are accessible
>> +via the processor PECI interface.
> 
> I had thought "DTS" referred to a fairly specific sensor in the CPU; is
> the same term also used for DIMM temp sensors or is the mention of it
> here a copy/paste error?
> 
>> +
>> +All temperature values are given in millidegree Celsius and will be measurable
>> +only when the target CPU is powered on.
>> +
>> +Sysfs interface
>> +-------------------
>> +
>> +======================= =======================================================
>> +
>> +temp[N]_label		Provides string "DIMM CI", where C is DIMM channel and
>> +			I is DIMM index of the populated DIMM.
>> +temp[N]_input		Provides current temperature of the populated DIMM.
>> +temp[N]_max		Provides thermal control temperature of the DIMM.
>> +temp[N]_crit		Provides shutdown temperature of the DIMM.
>> +
>> +======================= =======================================================
>> +
>> +Note:
>> +	DIMM temperature attributes will appear when the client CPU's BIOS
>> +	completes memory training and testing.
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 35ba9e3646bd..d16da127bbdc 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -14509,6 +14509,8 @@ M:	Iwona Winiarska <[e-mail]>
>> R:	Jae Hyun Yoo <[e-mail]>
>> L:	[e-mail]
>> S:	Supported
>> +F:	Documentation/hwmon/peci-cputemp.rst
>> +F:	Documentation/hwmon/peci-dimmtemp.rst
>> F:	drivers/hwmon/peci/
>>
>> PECI SUBSYSTEM
>> -- 
>> 2.31.1
>>
>

Winiarska, Iwona Aug. 2, 2021, 11:37 a.m. UTC | #3

On Tue, 2021-07-27 at 22:58 +0000, Zev Weiss wrote:
> On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
> > From: Jae Hyun Yoo <[e-mail]>
> > 
> > Add documentation for peci-cputemp driver that provides DTS thermal
> > readings for CPU packages and CPU cores and peci-dimmtemp driver that
> > provides DTS thermal readings for DIMMs.
> > 
> > Signed-off-by: Jae Hyun Yoo <[e-mail]>
> > Co-developed-by: Iwona Winiarska <[e-mail]>
> > Signed-off-by: Iwona Winiarska <[e-mail]>
> > Reviewed-by: Pierre-Louis Bossart <[e-mail]>
> > ---
> > Documentation/hwmon/index.rst         |  2 +
> > Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
> > Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
> > MAINTAINERS                           |  2 +
> > 4 files changed, 155 insertions(+)
> > create mode 100644 Documentation/hwmon/peci-cputemp.rst
> > create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
> > 
> > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> > index bc01601ea81a..cc76b5b3f791 100644
> > --- a/Documentation/hwmon/index.rst
> > +++ b/Documentation/hwmon/index.rst
> > @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
> >    pcf8591
> >    pim4328
> >    pm6764tr
> > +   peci-cputemp
> > +   peci-dimmtemp
> >    pmbus
> >    powr1220
> >    pxe1610
> > diff --git a/Documentation/hwmon/peci-cputemp.rst
> > b/Documentation/hwmon/peci-cputemp.rst
> > new file mode 100644
> > index 000000000000..d3a218ba810a
> > --- /dev/null
> > +++ b/Documentation/hwmon/peci-cputemp.rst
> > @@ -0,0 +1,93 @@
> > +.. SPDX-License-Identifier: GPL-2.0-only
> > +
> > +Kernel driver peci-cputemp
> > +==========================
> > +
> > +Supported chips:
> > +       One of Intel server CPUs listed below which is connected to a PECI
> > bus.
> > +               * Intel Xeon E5/E7 v3 server processors
> > +                       Intel Xeon E5-14xx v3 family
> > +                       Intel Xeon E5-24xx v3 family
> > +                       Intel Xeon E5-16xx v3 family
> > +                       Intel Xeon E5-26xx v3 family
> > +                       Intel Xeon E5-46xx v3 family
> > +                       Intel Xeon E7-48xx v3 family
> > +                       Intel Xeon E7-88xx v3 family
> > +               * Intel Xeon E5/E7 v4 server processors
> > +                       Intel Xeon E5-16xx v4 family
> > +                       Intel Xeon E5-26xx v4 family
> > +                       Intel Xeon E5-46xx v4 family
> > +                       Intel Xeon E7-48xx v4 family
> > +                       Intel Xeon E7-88xx v4 family
> > +               * Intel Xeon Scalable server processors
> > +                       Intel Xeon D family
> > +                       Intel Xeon Bronze family
> > +                       Intel Xeon Silver family
> > +                       Intel Xeon Gold family
> > +                       Intel Xeon Platinum family
> > +
> > +       Datasheet: Available from http://www.intel.com/design/literature.htm
> > +
> > +Author: Jae Hyun Yoo <[e-mail]>
> > +
> > +Description
> > +-----------
> > +
> > +This driver implements a generic PECI hwmon feature which provides Digital
> > +Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that
> > are
> > +accessible via the processor PECI interface.
> > +
> > +All temperature values are given in millidegree Celsius and will be
> > measurable
> > +only when the target CPU is powered on.
> > +
> > +Sysfs interface
> > +-------------------
> > +
> > +=======================
> > =======================================================
> > +temp1_label            "Die"
> > +temp1_input            Provides current die temperature of the CPU package.
> > +temp1_max              Provides thermal control temperature of the CPU
> > package
> > +                       which is also known as Tcontrol.
> > +temp1_crit             Provides shutdown temperature of the CPU package
> > which
> > +                       is also known as the maximum processor junction
> > +                       temperature, Tjmax or Tprochot.
> > +temp1_crit_hyst                Provides the hysteresis value from Tcontrol
> > to Tjmax of
> > +                       the CPU package.
> > +
> > +temp2_label            "DTS"
> > +temp2_input            Provides current DTS temperature of the CPU package.
> 
> Would this be a good place to note the slightly counter-intuitive nature
> of DTS readings?  i.e. add something along the lines of "The DTS sensor
> produces a delta relative to Tjmax, so negative values are normal and
> values approaching zero are hot."  (In my experience people who aren't
> already familiar with it tend to think something's wrong when a CPU
> temperature reading shows -50C.)

I believe that what you're referring to is a result of "GetTemp", and we're
using it to calculate "Die" sensor values (temp1).
The sensor value is absolute - we don't expose "raw" thermal sensor value
(delta) anywhere.

DTS sensor is exposing temperature value scaled to fit DTS 2.0 thermal profile: 
https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-thermal-guide.html
(section 5.2.3.2)

Similar to "Die" sensor - it's also exposed in absolute form.

I'll try to change description to avoid confusion.

> 
> > +temp2_max              Provides thermal control temperature of the CPU
> > package
> > +                       which is also known as Tcontrol.
> > +temp2_crit             Provides shutdown temperature of the CPU package which
> > +                       is also known as the maximum processor junction
> > +                       temperature, Tjmax or Tprochot.
> > +temp2_crit_hyst                Provides the hysteresis value from Tcontrol to
> > Tjmax of
> > +                       the CPU package.
> > +
> > +temp3_label            "Tcontrol"
> > +temp3_input            Provides current Tcontrol temperature of the CPU
> > +                       package which is also known as Fan Temperature target.
> > +                       Indicates the relative value from thermal monitor trip
> > +                       temperature at which fans should be engaged.
> > +temp3_crit             Provides Tcontrol critical value of the CPU package
> > +                       which is same to Tjmax.
> > +
> > +temp4_label            "Tthrottle"
> > +temp4_input            Provides current Tthrottle temperature of the CPU
> > +                       package. Used for throttling temperature. If this
> > value
> > +                       is allowed and lower than Tjmax - the throttle will
> > +                       occur and reported at lower than Tjmax.
> > +
> > +temp5_label            "Tjmax"
> > +temp5_input            Provides the maximum junction temperature, Tjmax of
> > the
> > +                       CPU package.
> > +
> > +temp[6-N]_label                Provides string "Core X", where X is resolved
> > core
> > +                       number.
> > +temp[6-N]_input                Provides current temperature of each core.
> > +temp[6-N]_max          Provides thermal control temperature of the core.
> > +temp[6-N]_crit         Provides shutdown temperature of the core.
> > +temp[6-N]_crit_hyst    Provides the hysteresis value from Tcontrol to Tjmax
> > of
> > +                       the core.
> 
> I only see *_label and *_input for the per-core temperature sensors, no
> *_max, *_crit, or *_crit_hyst.

You're right - this should be removed from documentation.

> 
> > +
> > +=======================
> > =======================================================
> > diff --git a/Documentation/hwmon/peci-dimmtemp.rst b/Documentation/hwmon/peci-
> > dimmtemp.rst
> > new file mode 100644
> > index 000000000000..1778d9317e43
> > --- /dev/null
> > +++ b/Documentation/hwmon/peci-dimmtemp.rst
> > @@ -0,0 +1,58 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +Kernel driver peci-dimmtemp
> > +===========================
> > +
> > +Supported chips:
> > +       One of Intel server CPUs listed below which is connected to a PECI
> > bus.
> > +               * Intel Xeon E5/E7 v3 server processors
> > +                       Intel Xeon E5-14xx v3 family
> > +                       Intel Xeon E5-24xx v3 family
> > +                       Intel Xeon E5-16xx v3 family
> > +                       Intel Xeon E5-26xx v3 family
> > +                       Intel Xeon E5-46xx v3 family
> > +                       Intel Xeon E7-48xx v3 family
> > +                       Intel Xeon E7-88xx v3 family
> > +               * Intel Xeon E5/E7 v4 server processors
> > +                       Intel Xeon E5-16xx v4 family
> > +                       Intel Xeon E5-26xx v4 family
> > +                       Intel Xeon E5-46xx v4 family
> > +                       Intel Xeon E7-48xx v4 family
> > +                       Intel Xeon E7-88xx v4 family
> > +               * Intel Xeon Scalable server processors
> > +                       Intel Xeon D family
> > +                       Intel Xeon Bronze family
> > +                       Intel Xeon Silver family
> > +                       Intel Xeon Gold family
> > +                       Intel Xeon Platinum family
> > +
> > +       Datasheet: Available from http://www.intel.com/design/literature.htm
> > +
> > +Author: Jae Hyun Yoo <[e-mail]>
> > +
> > +Description
> > +-----------
> > +
> > +This driver implements a generic PECI hwmon feature which provides Digital
> > +Thermal Sensor (DTS) thermal readings of DIMM components that are accessible
> > +via the processor PECI interface.
> 
> I had thought "DTS" referred to a fairly specific sensor in the CPU; is
> the same term also used for DIMM temp sensors or is the mention of it
> here a copy/paste error?

Yeah - it should be "Temperature Sensor on DIMM".

Thanks
-Iwona

> 
> > +
> > +All temperature values are given in millidegree Celsius and will be
> > measurable
> > +only when the target CPU is powered on.
> > +
> > +Sysfs interface
> > +-------------------
> > +
> > +=======================
> > =======================================================
> > +
> > +temp[N]_label          Provides string "DIMM CI", where C is DIMM channel and
> > +                       I is DIMM index of the populated DIMM.
> > +temp[N]_input          Provides current temperature of the populated DIMM.
> > +temp[N]_max            Provides thermal control temperature of the DIMM.
> > +temp[N]_crit           Provides shutdown temperature of the DIMM.
> > +
> > +=======================
> > =======================================================
> > +
> > +Note:
> > +       DIMM temperature attributes will appear when the client CPU's BIOS
> > +       completes memory training and testing.
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 35ba9e3646bd..d16da127bbdc 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -14509,6 +14509,8 @@ M:      Iwona Winiarska <[e-mail]>
> > R:      Jae Hyun Yoo <[e-mail]>
> > L:      [e-mail]
> > S:      Supported
> > +F:     Documentation/hwmon/peci-cputemp.rst
> > +F:     Documentation/hwmon/peci-dimmtemp.rst
> > F:      drivers/hwmon/peci/
> > 
> > PECI SUBSYSTEM
> > -- 
> > 2.31.1

Winiarska, Iwona Aug. 2, 2021, 11:39 a.m. UTC | #4

On Tue, 2021-07-27 at 17:49 -0700, Guenter Roeck wrote:
> On 7/27/21 3:58 PM, Zev Weiss wrote:
> > On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
> > > From: Jae Hyun Yoo <[e-mail]>
> > > 
> > > Add documentation for peci-cputemp driver that provides DTS thermal
> > > readings for CPU packages and CPU cores and peci-dimmtemp driver that
> > > provides DTS thermal readings for DIMMs.
> > > 
> > > Signed-off-by: Jae Hyun Yoo <[e-mail]>
> > > Co-developed-by: Iwona Winiarska <[e-mail]>
> > > Signed-off-by: Iwona Winiarska <[e-mail]>
> > > Reviewed-by: Pierre-Louis Bossart <[e-mail]>
> > > ---
> > > Documentation/hwmon/index.rst         |  2 +
> > > Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
> > > Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
> > > MAINTAINERS                           |  2 +
> > > 4 files changed, 155 insertions(+)
> > > create mode 100644 Documentation/hwmon/peci-cputemp.rst
> > > create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
> > > 
> > > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> > > index bc01601ea81a..cc76b5b3f791 100644
> > > --- a/Documentation/hwmon/index.rst
> > > +++ b/Documentation/hwmon/index.rst
> > > @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
> > >     pcf8591
> > >     pim4328
> > >     pm6764tr
> > > +   peci-cputemp
> > > +   peci-dimmtemp
> > >     pmbus
> > >     powr1220
> > >     pxe1610
> > > diff --git a/Documentation/hwmon/peci-cputemp.rst
> > > b/Documentation/hwmon/peci-cputemp.rst
> > > new file mode 100644
> > > index 000000000000..d3a218ba810a
> > > --- /dev/null
> > > +++ b/Documentation/hwmon/peci-cputemp.rst
> > > @@ -0,0 +1,93 @@
> > > +.. SPDX-License-Identifier: GPL-2.0-only
> > > +
> > > +Kernel driver peci-cputemp
> > > +==========================
> > > +
> > > +Supported chips:
> > > +       One of Intel server CPUs listed below which is connected to a PECI
> > > bus.
> > > +               * Intel Xeon E5/E7 v3 server processors
> > > +                       Intel Xeon E5-14xx v3 family
> > > +                       Intel Xeon E5-24xx v3 family
> > > +                       Intel Xeon E5-16xx v3 family
> > > +                       Intel Xeon E5-26xx v3 family
> > > +                       Intel Xeon E5-46xx v3 family
> > > +                       Intel Xeon E7-48xx v3 family
> > > +                       Intel Xeon E7-88xx v3 family
> > > +               * Intel Xeon E5/E7 v4 server processors
> > > +                       Intel Xeon E5-16xx v4 family
> > > +                       Intel Xeon E5-26xx v4 family
> > > +                       Intel Xeon E5-46xx v4 family
> > > +                       Intel Xeon E7-48xx v4 family
> > > +                       Intel Xeon E7-88xx v4 family
> > > +               * Intel Xeon Scalable server processors
> > > +                       Intel Xeon D family
> > > +                       Intel Xeon Bronze family
> > > +                       Intel Xeon Silver family
> > > +                       Intel Xeon Gold family
> > > +                       Intel Xeon Platinum family
> > > +
> > > +       Datasheet: Available from http://www.intel.com/design/literature.htm
> > > +
> > > +Author: Jae Hyun Yoo <[e-mail]>
> > > +
> > > +Description
> > > +-----------
> > > +
> > > +This driver implements a generic PECI hwmon feature which provides Digital
> > > +Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that
> > > are
> > > +accessible via the processor PECI interface.
> > > +
> > > +All temperature values are given in millidegree Celsius and will be
> > > measurable
> > > +only when the target CPU is powered on.
> > > +
> > > +Sysfs interface
> > > +-------------------
> > > +
> > > +=======================
> > > =======================================================
> > > +temp1_label            "Die"
> > > +temp1_input            Provides current die temperature of the CPU package.
> > > +temp1_max              Provides thermal control temperature of the CPU
> > > package
> > > +                       which is also known as Tcontrol.
> > > +temp1_crit             Provides shutdown temperature of the CPU package
> > > which
> > > +                       is also known as the maximum processor junction
> > > +                       temperature, Tjmax or Tprochot.
> > > +temp1_crit_hyst                Provides the hysteresis value from Tcontrol
> > > to Tjmax of
> > > +                       the CPU package.
> > > +
> > > +temp2_label            "DTS"
> > > +temp2_input            Provides current DTS temperature of the CPU package.
> > 
> > Would this be a good place to note the slightly counter-intuitive nature
> > of DTS readings?  i.e. add something along the lines of "The DTS sensor
> > produces a delta relative to Tjmax, so negative values are normal and
> > values approaching zero are hot."  (In my experience people who aren't
> > already familiar with it tend to think something's wrong when a CPU
> > temperature reading shows -50C.)
> > 
> 
> All attributes shall follow the ABI, and the driver must translate reported
> values to degrees C. If those sensors do not follow the ABI and report something
> else, I won't accept the driver.
> 
> Guenter

Sure, I believe all attributes already follow the ABI and the reported values
are in millidegree Celsius.

Thanks
-Iwona
>

Zev Weiss Aug. 4, 2021, 5:52 p.m. UTC | #5

On Mon, Aug 02, 2021 at 06:37:30AM CDT, Winiarska, Iwona wrote:
>On Tue, 2021-07-27 at 22:58 +0000, Zev Weiss wrote:
>> On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
>> > From: Jae Hyun Yoo <[e-mail]>
>> >
>> > Add documentation for peci-cputemp driver that provides DTS thermal
>> > readings for CPU packages and CPU cores and peci-dimmtemp driver that
>> > provides DTS thermal readings for DIMMs.
>> >
>> > Signed-off-by: Jae Hyun Yoo <[e-mail]>
>> > Co-developed-by: Iwona Winiarska <[e-mail]>
>> > Signed-off-by: Iwona Winiarska <[e-mail]>
>> > Reviewed-by: Pierre-Louis Bossart <[e-mail]>
>> > ---
>> > Documentation/hwmon/index.rst         |  2 +
>> > Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
>> > Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
>> > MAINTAINERS                           |  2 +
>> > 4 files changed, 155 insertions(+)
>> > create mode 100644 Documentation/hwmon/peci-cputemp.rst
>> > create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
>> >
>> > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
>> > index bc01601ea81a..cc76b5b3f791 100644
>> > --- a/Documentation/hwmon/index.rst
>> > +++ b/Documentation/hwmon/index.rst
>> > @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
>> >    pcf8591
>> >    pim4328
>> >    pm6764tr
>> > +   peci-cputemp
>> > +   peci-dimmtemp
>> >    pmbus
>> >    powr1220
>> >    pxe1610
>> > diff --git a/Documentation/hwmon/peci-cputemp.rst
>> > b/Documentation/hwmon/peci-cputemp.rst
>> > new file mode 100644
>> > index 000000000000..d3a218ba810a
>> > --- /dev/null
>> > +++ b/Documentation/hwmon/peci-cputemp.rst
>> > @@ -0,0 +1,93 @@
>> > +.. SPDX-License-Identifier: GPL-2.0-only
>> > +
>> > +Kernel driver peci-cputemp
>> > +==========================
>> > +
>> > +Supported chips:
>> > +       One of Intel server CPUs listed below which is connected to a PECI
>> > bus.
>> > +               * Intel Xeon E5/E7 v3 server processors
>> > +                       Intel Xeon E5-14xx v3 family
>> > +                       Intel Xeon E5-24xx v3 family
>> > +                       Intel Xeon E5-16xx v3 family
>> > +                       Intel Xeon E5-26xx v3 family
>> > +                       Intel Xeon E5-46xx v3 family
>> > +                       Intel Xeon E7-48xx v3 family
>> > +                       Intel Xeon E7-88xx v3 family
>> > +               * Intel Xeon E5/E7 v4 server processors
>> > +                       Intel Xeon E5-16xx v4 family
>> > +                       Intel Xeon E5-26xx v4 family
>> > +                       Intel Xeon E5-46xx v4 family
>> > +                       Intel Xeon E7-48xx v4 family
>> > +                       Intel Xeon E7-88xx v4 family
>> > +               * Intel Xeon Scalable server processors
>> > +                       Intel Xeon D family
>> > +                       Intel Xeon Bronze family
>> > +                       Intel Xeon Silver family
>> > +                       Intel Xeon Gold family
>> > +                       Intel Xeon Platinum family
>> > +
>> > +       Datasheet: Available from http://www.intel.com/design/literature.htm
>> > +
>> > +Author: Jae Hyun Yoo <[e-mail]>
>> > +
>> > +Description
>> > +-----------
>> > +
>> > +This driver implements a generic PECI hwmon feature which provides Digital
>> > +Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that
>> > are
>> > +accessible via the processor PECI interface.
>> > +
>> > +All temperature values are given in millidegree Celsius and will be
>> > measurable
>> > +only when the target CPU is powered on.
>> > +
>> > +Sysfs interface
>> > +-------------------
>> > +
>> > +=======================
>> > =======================================================
>> > +temp1_label            "Die"
>> > +temp1_input            Provides current die temperature of the CPU package.
>> > +temp1_max              Provides thermal control temperature of the CPU
>> > package
>> > +                       which is also known as Tcontrol.
>> > +temp1_crit             Provides shutdown temperature of the CPU package
>> > which
>> > +                       is also known as the maximum processor junction
>> > +                       temperature, Tjmax or Tprochot.
>> > +temp1_crit_hyst                Provides the hysteresis value from Tcontrol
>> > to Tjmax of
>> > +                       the CPU package.
>> > +
>> > +temp2_label            "DTS"
>> > +temp2_input            Provides current DTS temperature of the CPU package.
>>
>> Would this be a good place to note the slightly counter-intuitive nature
>> of DTS readings?  i.e. add something along the lines of "The DTS sensor
>> produces a delta relative to Tjmax, so negative values are normal and
>> values approaching zero are hot."  (In my experience people who aren't
>> already familiar with it tend to think something's wrong when a CPU
>> temperature reading shows -50C.)
>
>I believe that what you're referring to is a result of "GetTemp", and we're
>using it to calculate "Die" sensor values (temp1).
>The sensor value is absolute - we don't expose "raw" thermal sensor value
>(delta) anywhere.
>
>DTS sensor is exposing temperature value scaled to fit DTS 2.0 thermal profile:
>https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-thermal-guide.html
>(section 5.2.3.2)
>
>Similar to "Die" sensor - it's also exposed in absolute form.
>
>I'll try to change description to avoid confusion.
>

When I tested the patch series by applying it to my OpenBMC kernel, the
temp2_input sysfs file produced negative numbers (as has been the case
with previous iterations of the PECI patchset).  Is that expected?  From
what Guenter has said it sounds like that's going to need to change so
that the temperature readings are all in "normal" millidegrees C
(that is, relative to the freezing point of water).


Zev

Guenter Roeck Aug. 4, 2021, 6:05 p.m. UTC | #6

On 8/4/21 10:52 AM, Zev Weiss wrote:
> On Mon, Aug 02, 2021 at 06:37:30AM CDT, Winiarska, Iwona wrote:
>> On Tue, 2021-07-27 at 22:58 +0000, Zev Weiss wrote:
>>> On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
>>>> From: Jae Hyun Yoo <[e-mail]>
>>>>
>>>> Add documentation for peci-cputemp driver that provides DTS thermal
>>>> readings for CPU packages and CPU cores and peci-dimmtemp driver that
>>>> provides DTS thermal readings for DIMMs.
>>>>
>>>> Signed-off-by: Jae Hyun Yoo <[e-mail]>
>>>> Co-developed-by: Iwona Winiarska <[e-mail]>
>>>> Signed-off-by: Iwona Winiarska <[e-mail]>
>>>> Reviewed-by: Pierre-Louis Bossart <[e-mail]>
>>>> ---
>>>> Documentation/hwmon/index.rst         |  2 +
>>>> Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
>>>> Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
>>>> MAINTAINERS                           |  2 +
>>>> 4 files changed, 155 insertions(+)
>>>> create mode 100644 Documentation/hwmon/peci-cputemp.rst
>>>> create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
>>>>
>>>> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
>>>> index bc01601ea81a..cc76b5b3f791 100644
>>>> --- a/Documentation/hwmon/index.rst
>>>> +++ b/Documentation/hwmon/index.rst
>>>> @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
>>>>     pcf8591
>>>>     pim4328
>>>>     pm6764tr
>>>> +   peci-cputemp
>>>> +   peci-dimmtemp
>>>>     pmbus
>>>>     powr1220
>>>>     pxe1610
>>>> diff --git a/Documentation/hwmon/peci-cputemp.rst
>>>> b/Documentation/hwmon/peci-cputemp.rst
>>>> new file mode 100644
>>>> index 000000000000..d3a218ba810a
>>>> --- /dev/null
>>>> +++ b/Documentation/hwmon/peci-cputemp.rst
>>>> @@ -0,0 +1,93 @@
>>>> +.. SPDX-License-Identifier: GPL-2.0-only
>>>> +
>>>> +Kernel driver peci-cputemp
>>>> +==========================
>>>> +
>>>> +Supported chips:
>>>> +       One of Intel server CPUs listed below which is connected to a PECI
>>>> bus.
>>>> +               * Intel Xeon E5/E7 v3 server processors
>>>> +                       Intel Xeon E5-14xx v3 family
>>>> +                       Intel Xeon E5-24xx v3 family
>>>> +                       Intel Xeon E5-16xx v3 family
>>>> +                       Intel Xeon E5-26xx v3 family
>>>> +                       Intel Xeon E5-46xx v3 family
>>>> +                       Intel Xeon E7-48xx v3 family
>>>> +                       Intel Xeon E7-88xx v3 family
>>>> +               * Intel Xeon E5/E7 v4 server processors
>>>> +                       Intel Xeon E5-16xx v4 family
>>>> +                       Intel Xeon E5-26xx v4 family
>>>> +                       Intel Xeon E5-46xx v4 family
>>>> +                       Intel Xeon E7-48xx v4 family
>>>> +                       Intel Xeon E7-88xx v4 family
>>>> +               * Intel Xeon Scalable server processors
>>>> +                       Intel Xeon D family
>>>> +                       Intel Xeon Bronze family
>>>> +                       Intel Xeon Silver family
>>>> +                       Intel Xeon Gold family
>>>> +                       Intel Xeon Platinum family
>>>> +
>>>> +       Datasheet: Available from http://www.intel.com/design/literature.htm
>>>> +
>>>> +Author: Jae Hyun Yoo <[e-mail]>
>>>> +
>>>> +Description
>>>> +-----------
>>>> +
>>>> +This driver implements a generic PECI hwmon feature which provides Digital
>>>> +Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that
>>>> are
>>>> +accessible via the processor PECI interface.
>>>> +
>>>> +All temperature values are given in millidegree Celsius and will be
>>>> measurable
>>>> +only when the target CPU is powered on.
>>>> +
>>>> +Sysfs interface
>>>> +-------------------
>>>> +
>>>> +=======================
>>>> =======================================================
>>>> +temp1_label            "Die"
>>>> +temp1_input            Provides current die temperature of the CPU package.
>>>> +temp1_max              Provides thermal control temperature of the CPU
>>>> package
>>>> +                       which is also known as Tcontrol.
>>>> +temp1_crit             Provides shutdown temperature of the CPU package
>>>> which
>>>> +                       is also known as the maximum processor junction
>>>> +                       temperature, Tjmax or Tprochot.
>>>> +temp1_crit_hyst                Provides the hysteresis value from Tcontrol
>>>> to Tjmax of
>>>> +                       the CPU package.
>>>> +
>>>> +temp2_label            "DTS"
>>>> +temp2_input            Provides current DTS temperature of the CPU package.
>>>
>>> Would this be a good place to note the slightly counter-intuitive nature
>>> of DTS readings?  i.e. add something along the lines of "The DTS sensor
>>> produces a delta relative to Tjmax, so negative values are normal and
>>> values approaching zero are hot."  (In my experience people who aren't
>>> already familiar with it tend to think something's wrong when a CPU
>>> temperature reading shows -50C.)
>>
>> I believe that what you're referring to is a result of "GetTemp", and we're
>> using it to calculate "Die" sensor values (temp1).
>> The sensor value is absolute - we don't expose "raw" thermal sensor value
>> (delta) anywhere.
>>
>> DTS sensor is exposing temperature value scaled to fit DTS 2.0 thermal profile:
>> https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-thermal-guide.html
>> (section 5.2.3.2)
>>
>> Similar to "Die" sensor - it's also exposed in absolute form.
>>
>> I'll try to change description to avoid confusion.
>>
> 
> When I tested the patch series by applying it to my OpenBMC kernel, the
> temp2_input sysfs file produced negative numbers (as has been the case
> with previous iterations of the PECI patchset).  Is that expected?  From
> what Guenter has said it sounds like that's going to need to change so
> that the temperature readings are all in "normal" millidegrees C
> (that is, relative to the freezing point of water).
> 

Correct, the temperature is expected to be reported in millidegrees C
per hwmon ABI. Everything else is unacceptable. That makes me wonder what
"raw" and "absolute" means. Negative numbers suggest that, whatever is
reported today, it is not millidegrees C.

Guenter

Winiarska, Iwona Aug. 5, 2021, 9:42 p.m. UTC | #7

On Wed, 2021-08-04 at 11:05 -0700, Guenter Roeck wrote:
> On 8/4/21 10:52 AM, Zev Weiss wrote:
> > On Mon, Aug 02, 2021 at 06:37:30AM CDT, Winiarska, Iwona wrote:
> > > On Tue, 2021-07-27 at 22:58 +0000, Zev Weiss wrote:
> > > > On Mon, Jul 12, 2021 at 05:04:46PM CDT, Iwona Winiarska wrote:
> > > > > From: Jae Hyun Yoo <[e-mail]>
> > > > > 
> > > > > Add documentation for peci-cputemp driver that provides DTS thermal
> > > > > readings for CPU packages and CPU cores and peci-dimmtemp driver that
> > > > > provides DTS thermal readings for DIMMs.
> > > > > 
> > > > > Signed-off-by: Jae Hyun Yoo <[e-mail]>
> > > > > Co-developed-by: Iwona Winiarska <[e-mail]>
> > > > > Signed-off-by: Iwona Winiarska <[e-mail]>
> > > > > Reviewed-by: Pierre-Louis Bossart
> > > > > <[e-mail]>
> > > > > ---
> > > > > Documentation/hwmon/index.rst         |  2 +
> > > > > Documentation/hwmon/peci-cputemp.rst  | 93 +++++++++++++++++++++++++++
> > > > > Documentation/hwmon/peci-dimmtemp.rst | 58 +++++++++++++++++
> > > > > MAINTAINERS                           |  2 +
> > > > > 4 files changed, 155 insertions(+)
> > > > > create mode 100644 Documentation/hwmon/peci-cputemp.rst
> > > > > create mode 100644 Documentation/hwmon/peci-dimmtemp.rst
> > > > > 
> > > > > diff --git a/Documentation/hwmon/index.rst
> > > > > b/Documentation/hwmon/index.rst
> > > > > index bc01601ea81a..cc76b5b3f791 100644
> > > > > --- a/Documentation/hwmon/index.rst
> > > > > +++ b/Documentation/hwmon/index.rst
> > > > > @@ -154,6 +154,8 @@ Hardware Monitoring Kernel Drivers
> > > > >     pcf8591
> > > > >     pim4328
> > > > >     pm6764tr
> > > > > +   peci-cputemp
> > > > > +   peci-dimmtemp
> > > > >     pmbus
> > > > >     powr1220
> > > > >     pxe1610
> > > > > diff --git a/Documentation/hwmon/peci-cputemp.rst
> > > > > b/Documentation/hwmon/peci-cputemp.rst
> > > > > new file mode 100644
> > > > > index 000000000000..d3a218ba810a
> > > > > --- /dev/null
> > > > > +++ b/Documentation/hwmon/peci-cputemp.rst
> > > > > @@ -0,0 +1,93 @@
> > > > > +.. SPDX-License-Identifier: GPL-2.0-only
> > > > > +
> > > > > +Kernel driver peci-cputemp
> > > > > +==========================
> > > > > +
> > > > > +Supported chips:
> > > > > +       One of Intel server CPUs listed below which is connected to a
> > > > > PECI
> > > > > bus.
> > > > > +               * Intel Xeon E5/E7 v3 server processors
> > > > > +                       Intel Xeon E5-14xx v3 family
> > > > > +                       Intel Xeon E5-24xx v3 family
> > > > > +                       Intel Xeon E5-16xx v3 family
> > > > > +                       Intel Xeon E5-26xx v3 family
> > > > > +                       Intel Xeon E5-46xx v3 family
> > > > > +                       Intel Xeon E7-48xx v3 family
> > > > > +                       Intel Xeon E7-88xx v3 family
> > > > > +               * Intel Xeon E5/E7 v4 server processors
> > > > > +                       Intel Xeon E5-16xx v4 family
> > > > > +                       Intel Xeon E5-26xx v4 family
> > > > > +                       Intel Xeon E5-46xx v4 family
> > > > > +                       Intel Xeon E7-48xx v4 family
> > > > > +                       Intel Xeon E7-88xx v4 family
> > > > > +               * Intel Xeon Scalable server processors
> > > > > +                       Intel Xeon D family
> > > > > +                       Intel Xeon Bronze family
> > > > > +                       Intel Xeon Silver family
> > > > > +                       Intel Xeon Gold family
> > > > > +                       Intel Xeon Platinum family
> > > > > +
> > > > > +       Datasheet: Available from
> > > > > http://www.intel.com/design/literature.htm
> > > > > +
> > > > > +Author: Jae Hyun Yoo <[e-mail]>
> > > > > +
> > > > > +Description
> > > > > +-----------
> > > > > +
> > > > > +This driver implements a generic PECI hwmon feature which provides
> > > > > Digital
> > > > > +Thermal Sensor (DTS) thermal readings of the CPU package and CPU
> > > > > cores that
> > > > > are
> > > > > +accessible via the processor PECI interface.
> > > > > +
> > > > > +All temperature values are given in millidegree Celsius and will be
> > > > > measurable
> > > > > +only when the target CPU is powered on.
> > > > > +
> > > > > +Sysfs interface
> > > > > +-------------------
> > > > > +
> > > > > +=======================
> > > > > =======================================================
> > > > > +temp1_label            "Die"
> > > > > +temp1_input            Provides current die temperature of the CPU
> > > > > package.
> > > > > +temp1_max              Provides thermal control temperature of the
> > > > > CPU
> > > > > package
> > > > > +                       which is also known as Tcontrol.
> > > > > +temp1_crit             Provides shutdown temperature of the CPU
> > > > > package
> > > > > which
> > > > > +                       is also known as the maximum processor
> > > > > junction
> > > > > +                       temperature, Tjmax or Tprochot.
> > > > > +temp1_crit_hyst                Provides the hysteresis value from
> > > > > Tcontrol
> > > > > to Tjmax of
> > > > > +                       the CPU package.
> > > > > +
> > > > > +temp2_label            "DTS"
> > > > > +temp2_input            Provides current DTS temperature of the CPU
> > > > > package.
> > > > 
> > > > Would this be a good place to note the slightly counter-intuitive nature
> > > > of DTS readings?  i.e. add something along the lines of "The DTS sensor
> > > > produces a delta relative to Tjmax, so negative values are normal and
> > > > values approaching zero are hot."  (In my experience people who aren't
> > > > already familiar with it tend to think something's wrong when a CPU
> > > > temperature reading shows -50C.)
> > > 
> > > I believe that what you're referring to is a result of "GetTemp", and
> > > we're
> > > using it to calculate "Die" sensor values (temp1).
> > > The sensor value is absolute - we don't expose "raw" thermal sensor value
> > > (delta) anywhere.
> > > 
> > > DTS sensor is exposing temperature value scaled to fit DTS 2.0 thermal
> > > profile:
> > > https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-thermal-guide.html
> > > (section 5.2.3.2)
> > > 
> > > Similar to "Die" sensor - it's also exposed in absolute form.
> > > 
> > > I'll try to change description to avoid confusion.
> > > 
> > 
> > When I tested the patch series by applying it to my OpenBMC kernel, the
> > temp2_input sysfs file produced negative numbers (as has been the case
> > with previous iterations of the PECI patchset).  Is that expected?  From
> > what Guenter has said it sounds like that's going to need to change so
> > that the temperature readings are all in "normal" millidegrees C
> > (that is, relative to the freezing point of water).
> > 
> 
> Correct, the temperature is expected to be reported in millidegrees C
> per hwmon ABI. Everything else is unacceptable. That makes me wonder what
> "raw" and "absolute" means. Negative numbers suggest that, whatever is
> reported today, it is not millidegrees C.

Let's say we have two values: "base" and "delta". Both are in milidegrees C.
"absolute" means that the sensor value exposed to userspace is calculated as:
base - delta (or base + delta, depending on sensor).
"relative" would mean that we expose "delta" to userspace as sensor value.

For peci-cputemp (and dimmtemp) we're exposing sensors in "absolute" form.

I contacted Zev and we found that the platform he uses has a different format
for the "raw" value ("delta" in the example above) of this particular sensor
(S8.8 instead of S10.6), which means that we're subtracting significantly larger
number than we should, resulting in sensor going into negative.

On the platform I'm using for development purpose, sampling Die and DTS values
returned:
Die 26344
DTS 26329

The platform that Zev used is currently not supported by peci-cpu, however, I
went through the specs, and it looks like some of the older supported platforms
are also using S8.8.
I'll fix this in v3.

Thanks
-Iwona

> 
> Guenter

Patch

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index bc01601ea81a..cc76b5b3f791 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -154,6 +154,8 @@  Hardware Monitoring Kernel Drivers
    pcf8591
    pim4328
    pm6764tr
+   peci-cputemp
+   peci-dimmtemp
    pmbus
    powr1220
    pxe1610
diff --git a/Documentation/hwmon/peci-cputemp.rst b/Documentation/hwmon/peci-cputemp.rst
new file mode 100644
index 000000000000..d3a218ba810a
--- /dev/null
+++ b/Documentation/hwmon/peci-cputemp.rst
@@ -0,0 +1,93 @@ 
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver peci-cputemp
+==========================
+
+Supported chips:
+	One of Intel server CPUs listed below which is connected to a PECI bus.
+		* Intel Xeon E5/E7 v3 server processors
+			Intel Xeon E5-14xx v3 family
+			Intel Xeon E5-24xx v3 family
+			Intel Xeon E5-16xx v3 family
+			Intel Xeon E5-26xx v3 family
+			Intel Xeon E5-46xx v3 family
+			Intel Xeon E7-48xx v3 family
+			Intel Xeon E7-88xx v3 family
+		* Intel Xeon E5/E7 v4 server processors
+			Intel Xeon E5-16xx v4 family
+			Intel Xeon E5-26xx v4 family
+			Intel Xeon E5-46xx v4 family
+			Intel Xeon E7-48xx v4 family
+			Intel Xeon E7-88xx v4 family
+		* Intel Xeon Scalable server processors
+			Intel Xeon D family
+			Intel Xeon Bronze family
+			Intel Xeon Silver family
+			Intel Xeon Gold family
+			Intel Xeon Platinum family
+
+	Datasheet: Available from http://www.intel.com/design/literature.htm
+
+Author: Jae Hyun Yoo <[e-mail]>
+
+Description
+-----------
+
+This driver implements a generic PECI hwmon feature which provides Digital
+Thermal Sensor (DTS) thermal readings of the CPU package and CPU cores that are
+accessible via the processor PECI interface.
+
+All temperature values are given in millidegree Celsius and will be measurable
+only when the target CPU is powered on.
+
+Sysfs interface
+-------------------
+
+======================= =======================================================
+temp1_label		"Die"
+temp1_input		Provides current die temperature of the CPU package.
+temp1_max		Provides thermal control temperature of the CPU package
+			which is also known as Tcontrol.
+temp1_crit		Provides shutdown temperature of the CPU package which
+			is also known as the maximum processor junction
+			temperature, Tjmax or Tprochot.
+temp1_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
+			the CPU package.
+
+temp2_label		"DTS"
+temp2_input		Provides current DTS temperature of the CPU package.
+temp2_max		Provides thermal control temperature of the CPU package
+			which is also known as Tcontrol.
+temp2_crit		Provides shutdown temperature of the CPU package which
+			is also known as the maximum processor junction
+			temperature, Tjmax or Tprochot.
+temp2_crit_hyst		Provides the hysteresis value from Tcontrol to Tjmax of
+			the CPU package.
+
+temp3_label		"Tcontrol"
+temp3_input		Provides current Tcontrol temperature of the CPU
+			package which is also known as Fan Temperature target.
+			Indicates the relative value from thermal monitor trip
+			temperature at which fans should be engaged.
+temp3_crit		Provides Tcontrol critical value of the CPU package
+			which is same to Tjmax.
+
+temp4_label		"Tthrottle"
+temp4_input		Provides current Tthrottle temperature of the CPU
+			package. Used for throttling temperature. If this value
+			is allowed and lower than Tjmax - the throttle will
+			occur and reported at lower than Tjmax.
+
+temp5_label		"Tjmax"
+temp5_input		Provides the maximum junction temperature, Tjmax of the
+			CPU package.
+
+temp[6-N]_label		Provides string "Core X", where X is resolved core
+			number.
+temp[6-N]_input		Provides current temperature of each core.
+temp[6-N]_max		Provides thermal control temperature of the core.
+temp[6-N]_crit		Provides shutdown temperature of the core.
+temp[6-N]_crit_hyst	Provides the hysteresis value from Tcontrol to Tjmax of
+			the core.
+
+======================= =======================================================
diff --git a/Documentation/hwmon/peci-dimmtemp.rst b/Documentation/hwmon/peci-dimmtemp.rst
new file mode 100644
index 000000000000..1778d9317e43
--- /dev/null
+++ b/Documentation/hwmon/peci-dimmtemp.rst
@@ -0,0 +1,58 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver peci-dimmtemp
+===========================
+
+Supported chips:
+	One of Intel server CPUs listed below which is connected to a PECI bus.
+		* Intel Xeon E5/E7 v3 server processors
+			Intel Xeon E5-14xx v3 family
+			Intel Xeon E5-24xx v3 family
+			Intel Xeon E5-16xx v3 family
+			Intel Xeon E5-26xx v3 family
+			Intel Xeon E5-46xx v3 family
+			Intel Xeon E7-48xx v3 family
+			Intel Xeon E7-88xx v3 family
+		* Intel Xeon E5/E7 v4 server processors
+			Intel Xeon E5-16xx v4 family
+			Intel Xeon E5-26xx v4 family
+			Intel Xeon E5-46xx v4 family
+			Intel Xeon E7-48xx v4 family
+			Intel Xeon E7-88xx v4 family
+		* Intel Xeon Scalable server processors
+			Intel Xeon D family
+			Intel Xeon Bronze family
+			Intel Xeon Silver family
+			Intel Xeon Gold family
+			Intel Xeon Platinum family
+
+	Datasheet: Available from http://www.intel.com/design/literature.htm
+
+Author: Jae Hyun Yoo <[e-mail]>
+
+Description
+-----------
+
+This driver implements a generic PECI hwmon feature which provides Digital
+Thermal Sensor (DTS) thermal readings of DIMM components that are accessible
+via the processor PECI interface.
+
+All temperature values are given in millidegree Celsius and will be measurable
+only when the target CPU is powered on.
+
+Sysfs interface
+-------------------
+
+======================= =======================================================
+
+temp[N]_label		Provides string "DIMM CI", where C is DIMM channel and
+			I is DIMM index of the populated DIMM.
+temp[N]_input		Provides current temperature of the populated DIMM.
+temp[N]_max		Provides thermal control temperature of the DIMM.
+temp[N]_crit		Provides shutdown temperature of the DIMM.
+
+======================= =======================================================
+
+Note:
+	DIMM temperature attributes will appear when the client CPU's BIOS
+	completes memory training and testing.
diff --git a/MAINTAINERS b/MAINTAINERS
index 35ba9e3646bd..d16da127bbdc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14509,6 +14509,8 @@  M:	Iwona Winiarska <[e-mail]>
 R:	Jae Hyun Yoo <[e-mail]>
 L:	[e-mail]
 S:	Supported
+F:	Documentation/hwmon/peci-cputemp.rst
+F:	Documentation/hwmon/peci-dimmtemp.rst
 F:	drivers/hwmon/peci/
 
 PECI SUBSYSTEM