[spec] Initial PLDM draft (#37)

Initial middleware/pldm.md draft. This document is still WIP but it is
being open sourced to request feedback from the community.

Signed-off-by: Miguel Osorio <[email protected]>

Author: moidx

docs/src/specification/middleware/pldm.md

@@ -0,0 +1,69 @@
+## PLDM
+
+PLDM OpenPRoT devices will support Platform Level Data Model as a responder for
+FW updates and platform monitoring. This means that OpenPRoT will respond to
+Type 0, Type 2 and Type 5 as listed in Table 1\.
+
+## PLDM Base Specifications for Supported Types {#pldm-base-specifications-for-supported-types}
+
+### Type 0 - Base Specification
+
+*   Purpose: Base Specification and Initialization
+*   Version: 1.2.0
+*   [Platform Level Data Model (PLDM) Base Specification](https://www.dmtf.org/sites/default/files/standards/documents/DSP0240_1.2.0.pdf)
+
+All responders shall implement the four (4) *spec mandatory* PLDM commands:
+
+*   `GetTID`
+*   `GetPLDMVersion`
+*   `GetPLDMTypes`
+*   `GetPLDMCommands`
+
+All responders shall implement the following *optional* commands
+
+*   `SetTID`
+
+### Type 2 - Platform Monitoring and Control
+
+*   Purpose: Platform Monitoring and Control
+*   Version: 1.3.0
+*   [Platform Level Data Model (PLDM) for Platform Monitoring and Control
+    Specification](https://www.dmtf.org/sites/default/files/standards/documents/DSP0248_1.3.0.pdf)
+
+OpenPRoT will support PLDM Monitoring and Control by providing a PDR, Platform
+Descriptor Record, repository to a prospective PDLM Manageability Access Point
+Discovery Agent’s primary PDR. These PDRs will be defined via Json files and
+included into OpenPRoT at build time. OpenPRoT will not support any dynamic
+adjustments to the PDR repository. These PDRs should be limited to security
+features and as such, will only support PLDM sensors and not effectors. PLDM
+Monitoring PDRs
+
+*   Terminus Locator PDR
+*   Numeric Sensor PDR
+
+### Type 5 - Firmware Update
+
+*   Purpose: Firmware Update
+*   Version: 1.3.0
+*   [Platform Level Data Model (PLDM) for Firmware Update Specification](https://www.dmtf.org/sites/default/files/standards/documents/DSP0267_1.3.0.pdf)
+
+Required Inventory Commands:
+
+*   `QueryDeviceIdentifiers`
+*   `GetFirmwareParameters`
+
+Required Update Commands:
+
+*   `RequestFirmwareUpdate`
+*   `PassComponentTable`
+*   `UpdateComponent`
+*   `TransferComplete`
+*   `VerifyComplete`
+*   `ApplyComplete`
+*   `ActivateFirmware`
+*   `GetStatus`
+
+All responders shall implement the following optional commands
+
+*   `GetPackageData`
+*   `GetPackageMetaData`