docs: hwmon: Document PECI drivers

Add documentation for peci-cputemp driver that provides DTS thermal
readings for CPU packages and CPU cores, and peci-dimmtemp driver that
provides Temperature Sensor on DIMM readings.

Co-developed-by: Iwona Winiarska <iwona.winiarska@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
Link: https://lore.kernel.org/r/20220208153639.255278-13-iwona.winiarska@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 90 insertions, 0 deletions

diff --git a/Documentation/hwmon/peci-cputemp.rst b/Documentation/hwmon/peci-cputemp.rst
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+.. 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 <jae.hyun.yoo@linux.intel.com>
+
+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 temperature of the CPU package scaled
+			to match DTS thermal profile.
+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.
+
+======================= =======================================================