[PATCH v5 03/10] Documentation: hwmon: Add OCC documentation

From: Eddie James
Date: Thu Aug 30 2018 - 17:33:39 EST

Document the hwmon interface for the OCC.

Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxxxxxxx>
Documentation/hwmon/occ | 112 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
create mode 100644 Documentation/hwmon/occ

diff --git a/Documentation/hwmon/occ b/Documentation/hwmon/occ
new file mode 100644
index 0000000..adc2fa4
--- /dev/null
+++ b/Documentation/hwmon/occ
@@ -0,0 +1,112 @@
+Kernel driver occ-hwmon
+Supported chips:
+ * POWER8
+ * POWER9
+Author: Eddie James <eajames@xxxxxxxxxxxxxxxxxx>
+This driver supports hardware monitoring for the On-Chip Controller (OCC)
+embedded on POWER processors. The OCC is a device that collects and aggregates
+sensor data from the processor and the system. The OCC can provide the raw
+sensor data as well as perform thermal and power management on the system.
+The P8 version of this driver is a client driver of I2C. It may be probed
+manually if an "ibm,p8-occ-hwmon" compatible device is found under the
+appropriate I2C bus node in the device-tree.
+The P9 version of this driver is a client driver of the FSI-based OCC driver.
+It will be probed automatically by the FSI-based OCC driver.
+Sysfs entries
+The following attributes are supported. All attributes are read-only unless
+The OCC sensor ID is an integer that represents the unique identififer of the
+sensor with respect to the OCC. For example, a temperature sensor for the 3rd
+DIMM slot in the system may have a sensor ID of 7. This mapping is unavailable
+to the device driver, which must therefore export the sensor ID as-is.
+Some entries are only present with certain OCC sensor versions or only on
+certain OCCs in the system. The version number is not exported to the user
+but can be inferred.
+temp[1-n]_label OCC sensor ID.
+[with temperature sensor version 1]
+ temp[1-n]_input Measured temperature of the component in millidegrees
+ Celsius.
+[with temperature sensor version >= 2]
+ temp[1-n]_type The FRU (Field Replaceable Unit) type
+ (represented by an integer) for the component
+ that this sensor measures.
+ temp[1-n]_fault Temperature sensor fault boolean; 1 to indicate
+ that a fault is present or 0 to indicate that
+ no fault is present.
+ [with type == 3 (FRU type is VRM)]
+ temp[1-n]_alarm VRM temperature alarm boolean; 1 to indicate
+ alarm, 0 to indicate no alarm
+ [else]
+ temp[1-n]_input Measured temperature of the component in
+ millidegrees Celsius.
+freq[1-n]_label OCC sensor ID.
+freq[1-n]_input Measured frequency of the component in MHz.
+power[1-n]_input Latest measured power reading of the component in
+ microwatts.
+power[1-n]_average Average power of the component in microwatts.
+power[1-n]_average_interval The amount of time over which the power average
+ was taken in microseconds.
+[with power sensor version < 2]
+ power[1-n]_label OCC sensor ID.
+[with power sensor version >= 2]
+ power[1-n]_label OCC sensor ID + function ID + channel in the form
+ of a string, delimited by underscores, i.e. "0_15_1".
+ Both the function ID and channel are integers that
+ further identify the power sensor.
+[with power sensor version 0xa0]
+ power[1-n]_label OCC sensor ID + sensor type in the form of a string,
+ delimited by an underscore, i.e. "0_system". Sensor
+ type will be one of "system", "proc", "vdd" or "vdn".
+ For this sensor version, OCC sensor ID will be the same
+ for all power sensors.
+[present only on "master" OCC; represents the whole system power; only one of
+ this type of power sensor will be present]
+ power[1-n]_label "system"
+ power[1-n]_input Latest system output power in microwatts.
+ power[1-n]_cap Current system power cap in microwatts.
+ power[1-n]_cap_not_redundant System power cap in microwatts when
+ there is not redundant power.
+ power[1-n]_cap_max Maximum power cap that the OCC can enforce in
+ microwatts.
+ power[1-n]_cap_min Minimum power cap that the OCC can enforce in
+ microwatts.
+ power[1-n]_cap_user The power cap set by the user, in microwatts.
+ This attribute will return 0 if no user power
+ cap has been set. This attribute is read-write,
+ but writing any precision below watts will be
+ ignored, i.e. requesting a power cap of
+ 500900000 microwatts will result in a power cap
+ request of 500 watts.
+ [with caps sensor version > 1]
+ power[1-n]_cap_user_source Indicates how the user power cap was
+ set. This is an integer that maps to
+ system or firmware components that can
+ set the user power cap.
+The following "extn" sensors are exported as a way for the OCC to provide data
+that doesn't fit anywhere else. The meaning of these sensors is entirely
+dependent on their data, and cannot be statically defined.
+extn[1-n]_label ASCII ID or OCC sensor ID.
+extn[1-n]_flags This is one byte hexadecimal value. Bit 7 indicates the
+ type of the label attribute; 1 for sensor ID, 0 for
+ ASCII ID. Other bits are reserved.
+extn[1-n]_input 6 bytes of hexadecimal data, with a meaning defined by
+ the sensor ID.