phosphor-power-supply/docs/MultiChassis.md

1 # Multi-Chassis Support for phosphor-psu-monitor
5 Currently, **phosphor-psu-monitor** operates on a **single chassis**.
7 - It gets the PSUs device access information (such as PSU I2CBus and I2CAddress)
9 - The phosphor-psu-monitor uses a **fixed object path**, appended with the PSU
11 - Example of current PSU path:
17 ## Goal: Support Multi-Chassis PSUs
19 To support **multi-chassis**, the **phosphor-psu-monitor** requires the
22 - Define Chassis class
23 - Modify the **PSUManager** class to instantiate one **Chassis class** per
25 - Find all PSUs associated with each chassis.
26 - Update the PSUs status on DBus with appropriate path i.e.
36 - Chassis class constructor take parameters D-Bus connection object, chassis
38 - Vector of powerSupply instances
39 - Functions to get and add PSUs
40 - Function to get chassis status
44 - Add method to retrieve a list of chassis objects from the **inventory
46   for D-BUS events to track chassis PGOOD Status.
47 - Retrieve the PSU configurations from **entity manager**
48 - Find all PSUs associated with chassis from **inventory manager** (using
49   **[getSubTree](https://github.com/openbmc/phosphor-power/blob/master/utility.hpp)**)
50   and add them to vector in the chassis object. **getSubTree** is a function
51   interacts with the D-Bus object mapper to retrieve all objects under a
56 - The PSUManager object loops over all **chassis** that are present and have
57   standby power. The **phosphor-psu-monitor** app monitors all PSUs associated
59   - Monitor Presence
60   - Create appropriate journal entries
61   - Create PELs for faults if the chassis is powered on
65 - Update/publish **PSU sensors, presence and VPD information** on D-Bus.
66 - Ensure properties **reflect multi-chassis** support.
68 Note: The phosphor-psu-monitor logic should remain the same when adding support
69 for multi chassis.
73 - TBD
77 - Ensure any **error** references the **correct PSU inventory path**, e.g.,
78   - `/xyz/openbmc_project/inventory/system/chassis0/powersupply0`
79   - `/xyz/openbmc_project/inventory/system/chassis1/powersupply3`
83 - Update journal messages to reflect **appropriate chassis**.
85 ---
89 **phosphor-psu-monitor** must be enhanced to dynamically:
91 - Discover chassis, and maintain state of each chassis and react accordingly.
92 - Monitor PSUs across all chassis
93 - Update DBus and error logs accordingly.