1## Overview
2
3The `phosphor-regulators` application configures and monitors voltage
4regulators.  The application is controlled by a JSON configuration file.
5
6The application does not control how voltage regulators are enabled or how to
7monitor their Power Good (pgood) status.  Those operations are typically
8performed by power sequencer hardware and related firmware.
9
10
11## Configuring Voltage Regulators
12
13The configuration of voltage regulators can be modified.  Configuration changes
14usually override hardware default settings.
15
16The most common configuration change is setting the output voltage for a
17regulator rail.  Other examples include modifying pgood thresholds and
18overcurrent settings.
19
20The configuration changes are applied early in the boot process before
21regulators are enabled.
22
23
24## Monitoring Voltage Regulators
25
26Two types of regulator monitoring are supported:
27* Sensor monitoring
28* Phase fault monitoring
29
30### Sensor Monitoring
31
32The sensor values for a voltage rail are read, such as voltage output, current
33output, and temperature.  Sensor values are measured, actual values rather than
34target values.
35
36Sensors are read once per second.  The sensor values are stored on D-Bus on the
37BMC, making them available to external interfaces like Redfish.
38
39### Phase Fault Monitoring
40
41Some voltage regulators contain redundant phases.  If a redundant phase fails,
42the regulator can continue functioning normally.  However redundancy has been
43lost, and the regulator may fail if another phase fails.
44
45Voltage regulators can be monitored for redundant phase faults.  If a fault is
46detected, an error is logged on the BMC.
47
48
49## JSON Configuration File
50
51The JSON configuration file defines the following:
52* Voltage regulators in the system.
53* Operations to perform on those regulators, such as configuration or sensor
54  monitoring.
55
56Configuration files are stored in the `config_files` directory.
57
58See the [configuration file documentation](docs/config_file/README.md) for
59information on the file format, validation tool, and installation directories.
60