time-alarm-service-messages: Make discriminants pub

[kurtjd]

If we want to deserialize a time-alarm response, we need to know the discriminant:

embedded-services/time-alarm-service-messages/src/lib.rs

Line 292 in 16c4364

fn deserialize(discriminant: u16, buffer: &[u8]) -> Result<Self, MessageSerializationError> {

However, we can't call the trait method discriminant() yet since we don't have a constructed AcpiTimeAlarmResponse. So, make the Discriminant enums public so we can use that to pass a value into deserialize for the response type we are expecting.

This is needed for ec-test-app, e.g.:

impl RtcSource for Serial {
    fn get_capabilities(&self) -> Result<TimeAlarmDeviceCapabilities> {
        let request = AcpiTimeAlarmRequest::GetCapabilities;
        let response = self.send(
            Destination::TimeAlarm,
            request,
            // Need to pass in the expected discriminant to deserialize (which send() calls)
            // If not pub, then we would need to hardcode values here
            AcpiTimeAlarmResponseDiscriminant::Capabilities.into(),
        )?;

        if let AcpiTimeAlarmResponse::Capabilities(capabilities) = response {
            Ok(capabilities)
        } else {
            Err(eyre!("GET_CAPABILITIES received wrong response"))
        }
    }
}

[williampMSFT]

The discriminant should come from the MCTP packet header, no? I think I might be missing something

[kurtjd]

The discriminant should come from the MCTP packet header, no? I think I might be missing something

Yep, playing around with it the discriminant is found within the ODP response header as we discussed offline. So closing this as not necessary. Thanks!

[williampMSFT]

The discriminant should come from the MCTP packet header, no? I think I might be missing something

Yep, playing around with it the discriminant is found within the ODP response header as we discussed offline. So closing this as not necessary. Thanks!

sounds good, filed #715 on myself to clean up some of the header generation macros so they're easier to use from the host side; for now you can probably just manually grab it from the header like you mentioned