[williampMSFT]

This provides an implementation of the HID protocol relay handler for the time-alarm service based on the current draft of the HID time-alarm device spec.

To support this, it also introduces some support functions/macros for packing/unpacking HID reports.

The draft spec is subject to change, and in particular currently has some limitations around wake policy and expired timers that are being litigated and will almost certainly change in some capacity.

The actual waking is supposed to be done out-of-band (since a time-alarm device is responsible for powering on the device when it's powered off and the HID transport itself is therefore also powered off), but we don't have a power service implemented yet so that's out of scope for this change.

[williampMSFT]

Tested in conjunction with OpenDevicePartnership/odp-windows-drivers#13

[Copilot]

Copilot review overview

🟡 Changes recommended

Time-zone null handling and report-count metadata are incorrect, and the MCTP reorganization breaks existing public paths.

Review effort: Balanced
Findings: 1 · 3

Open (4)

• Report count capacity is too small for four report IDs · New
• Unknown ACPI time zone uses invalid HID sentinel · New
• Out-of-range HID null values become fabricated time zones · New
• Moving MCTP APIs breaks existing crate-root paths · New

What changed in this PR

Adds HID protocol support for the time-alarm service while retaining MCTP relay functionality.

Changes:

• Adds HID descriptors, report serialization, and relay handling.
• Introduces reusable bit-level HID report utilities.
• Adds an RT685 HID example and reorganizes MCTP exports.

File	Description
time-alarm-service-relay/​src/​mctp/​serialization.rs	Houses MCTP message serialization.
time-alarm-service-relay/​src/​mctp/​mod.rs	Houses the MCTP relay handler.
time-alarm-service-relay/​src/​lib.rs	Exposes HID and MCTP modules.
time-alarm-service-relay/​src/​hid/​SystemWakeTimerAndRtc.wara	Defines the HID report descriptor source.
time-alarm-service-relay/​src/​hid/​serialization.rs	Implements HID report encoding and descriptor data.
time-alarm-service-relay/​src/​hid/​mod.rs	Implements the time-alarm HID device adapter.
time-alarm-service-relay/​Cargo.toml	Adds HID-related dependency and feature wiring.
examples/​rt685s-evk/​src/​bin/​time_alarm_mctp.rs	Updates the MCTP handler path.
examples/​rt685s-evk/​src/​bin/​time_alarm_hid.rs	Adds an RT685 HID-over-I²C example.
examples/​rt685s-evk/​Cargo.lock	Records the example dependency update.
embedded-service/​src/​relay/​hid/​reports.rs	Adds generic bit-level HID report utilities.
embedded-service/​src/​relay/​hid/​mod.rs	Exports the report utilities and macro.
Cargo.lock	Records the workspace dependency update.

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[Copilot]

Copilot review overview

🔵 Needs a closer look

The failed time report emits date values outside the logical ranges declared by its HID descriptor.

Review effort: Balanced
Findings: None

Resolved since last review (4)

• Report count capacity is too small for four report IDs
• Moving MCTP APIs breaks existing crate-root paths
• Out-of-range HID null values become fabricated time zones
• Unknown ACPI time zone uses invalid HID sentinel

Previously missed (1)

In code that hasn't changed since last review

Use valid placeholder date values when clock read fails

time-alarm-service-relay/​src/​hid/​serialization.rs:182

Default::default() emits year/month/day as zero, but these input fields are declared with logical ranges 1900–9999, 1–12, and 1–31 and are not marked NullState. Thus a failed clock read sends a report that violates its own HID descriptor. Use in-range placeholder date values while current_state carries Failed.

[felipebalbi]

Would be nice to see tests for src/hid/*