docs/designs/psu-monitoring.md

1 # Power Supply Monitoring Application
7 Created: 2019-06-17
11 This is a proposal to provide a set of enhancements to the current OpenBMC power
13 may consist of a number of configuration variations including different power
15 different power supplies is needed in order to initialize the power supplies,
22 The OpenBMC project currently has a [witherspoon-pfault-analysis][1] repository
23 that contains a power supply monitor application and a power sequencer monitor
24 application. The current power supply application is lacking things desired for
28 a single power supply application that can communicate with one or more
29 [PMBus][2] power supplies and provide the enterprise features currently lacking
31 power supply.
38 1. The power supply application must detect, isolate, and report individual
39    input power and power FRU faults, during boot and at runtime only.
40 2. The power supply application must determine power supply presence,
42 3. The power supply application must report power supply failures to IPMI and
44 4. The power supply application must report power supply present/missing changes
47    moved from the `phosphor-dbus-monitor` to this application, depending on if
50 5. The power supply application must ensure proper power supply configuration
52 6. The power supply application must collect and report power supply VPD (unless
55 7. The power supply application must allow power supply hot-plug and concurrent
57 8. The power supply application should create and update average and maximum
58    power consumption metric interfaces for telemetry data.
59 9. The power supply application must be able to detect how many power supplies
60    are present in the system, what type of power supply is present (maximum
61    output power such as 900W, 1400W, 2200W, etc.), and what type of input power
63 10. The application must be able to recognize if the power supplies present
68     power supplies experiencing some other faulted condition (no input power,
70 12. The application would periodically communicate with the power supplies via
72     only known to be created and updated by the [ibm-cffps][4] device driver).
73     Certain device driver updates may be necessary to support some power
74     supplies or power supply features. Any power supply that communicates using
83 The proposal is to create a single new power supply application in the OpenBMC
84 [phosphor-power][6] repository. The application would be written in C++17.
86 Upon startup, the power supply application would be passed a parameter
88 file. This file would contain information such as the D-Bus object name(s),
89 possible power supply types, possible system types that the various power
90 supplies are valid to be used in, I2C/PMBus file location data, read retries,
93 The power supply application would then detect which system type it is running
94 on, which supplies are present, if the power supply is ready for reading VPD
100 When the system is powered on, the power supplies should start outputting power
102 monitor the supplies and communicate any changes such as removal of input
103 voltage, removal of a power supply, insertion of a power supply, and take any
106 The proposed power supply application would not control any fans internal to the
107 power supply, that function would be left to other userspace application(s).
111 The current implementation of multiple instances of a power supply monitor was
112 considered, essentially similar to the [psu-monitor][5] from the
113 [witherspoon-pfault-analysis][1] repository. This design was avoided due to:
115 - Complexity of the various valid and invalid configuration combinations.
116 - Power line disturbance communication.
117 - Timing/serialization concerns with power supply communication.
130 the one application per power supply.
136 - Configuration not listed as valid results in appropriate behavior.
137 - Application detects and logs faults for power supply faults including input
140 - Power supply VPD data reported for present power supplies.
141 - Power supply removal and insertion, on a system supporting concurrent
142   maintenance, does not result in power loss to powered on system.
143 - System operates through power supply faults and power line disturbances as
149 [1]: https://github.com/openbmc/witherspoon-pfault-analysis
152 …https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/yaml/xyz/openbmc_project/Control/R…
154   https://github.com/openbmc/linux/blob/dev-5.3/drivers/hwmon/pmbus/ibm-cffps.c
156   https://github.com/openbmc/witherspoon-pfault-analysis/tree/master/power-supply
157 [6]: https://github.com/openbmc/phosphor-power/