srvgrp-request-forward.adoc

Service Group - REQUEST_FORWARD (SERVICEGROUP_ID: 0x000C)

The REQUEST_FORWARD service group allows application processors to retrieve and process RPMI request messages which are forwarded by platform microcontroller from some other RPMI client. This service group also allows an SBI implementation to forward RPMI request messages from one system-level partition (or domain) to another using the SBI MPXY extension cite:[SBI].

The platform microcontroller (or SBI implementation) should maintain a first-in first-out queue of forwarded RPMI request messages. The first (or oldest) forwarded RPMI request message in the queue is referred to as the current forwarded RPMI request message. The RPMI services defined by the REQUEST_FORWARD service group allow application processors to retrieve and process one forwarded RPMI request message at a time.

The Request Forward Services below lists the services defined by the REQUEST_FORWARD service group:

Table 1. Request Forward Services

Service ID	Service Name	Request Type
0x01	REQFWD_ENABLE_NOTIFICATION	NORMAL_REQUEST
0x02	REQFWD_RETRIEVE_CURRENT_MESSAGE	NORMAL_REQUEST
0x03	REQFWD_COMPLETE_CURRENT_MESSAGE	NORMAL_REQUEST

Notifications

The Request Forward Notification Events below lists the notification events defined by the REQUEST_FORWARD service group.

Table 2. Request Forward Notification Events

Event ID	Name	Event Data	Description
0x01	REQFWD_NEW_MESSAGE	An array of N bytes representing the first N bytes of the current forwarded RPMI request message. The value N is specified by the EVENT_DATALEN field of the RPMI notification event as shown in [table_notification_message_format].	This RPMI notification event represents the arrival of a new forwarded RPMI request message when there were no other pending forwarded RPMI request message in the queue.

Service: REQFWD_ENABLE_NOTIFICATION (SERVICE_ID: 0x01)

This service allows the application processor to subscribe to REQUEST_FORWARD service group notifications. The platform may optionally support notifications for events that may occur. The platform microcontroller can send these notification messages to the application processor if they are implemented and the application processor has subscribed to them. The supported events are described in Notifications.

Table 3. Request Data

Word	Name	Type	Description
0	EVENT_ID	uint32	The event to be subscribed for notification.
1	REQ_STATE	uint32	Requested event notification state Change or query the current state of EVENT_ID notification. 0: Disable 1: Enable 2: Return current state. Any other values of REQ_STATE field other than the defined ones are reserved for future use.

Table 4. Response Data

Word	Name	Type	Description
0	STATUS	int32	Return error code Error Code Description RPMI_SUCCESS Event is subscribed successfully. RPMI_ERR_INVALID_PARAM EVENT_ID or REQ_STATE is invalid. RPMI_ERR_NOT_SUPPORTED Notification is not supported. Other errors [table_error_codes]
1	CURRENT_STATE	uint32	Current EVENT_ID notification state 0: Notification is disabled 1: Notification is enabled. In case of REQ_STATE = 0 or 1, the CURRENT_STATE will return the requested state. In case of an error, the value of CURRENT_STATE is unspecified.

Service: REQFWD_RETRIEVE_CURRENT_MESSAGE (SERVICE_ID: 0x02)

This service allows application processors to retrieve the current forwarded RPMI request message. The current message may be the oldest forwarded RPMI request message in the platform microcontroller (or SBI implementation) queue.

Table 5. Request Data

Word	Name	Type	Description
0	START_INDEX	uint32	Starting index of first byte of the current forwarded RPMI request message. Use 0 for the first call, subsequent calls will use the next index of the remaining bytes.

Table 6. Response Data

Word	Name	Type	Description
0	STATUS	int32	Return error code Error Code Description RPMI_SUCCESS Service completed successfully. RPMI_ERR_INVALID_PARAM START_INDEX is invalid. RPMI_ERR_NO_DATA No forwarded RPMI request message available. Other errors [table_error_codes]
1	REMAINING	uint32	Remaining number of bytes in the current forwarded RPMI request message.
2	RETURNED	uint32	Number of bytes N of the current forwarded RPMI request message returned in this request.
3	REQUEST_MESSAGE[N]	uint8	An array of N bytes representing a part of the current forwarded RPMI request message at byte offset specified by START_INDEX.

Service: REQFWD_COMPLETE_CURRENT_MESSAGE (SERVICE_ID: 0x03)

This service allows the application processors to inform the platform microcontroller (or SBI implementation) that:

• The processing of the current forwarded RPMI request message has completed and RPMI response message must be sent to the original source of RPMI request message.

• The current forwarded RPMI request message must now point to the next forwarded RPMI request message if available.

Table 7. Request Data

Word	Name	Type	Description
0	RESPONSE_DATA[N]	uint8	An array of bytes representing the RPMI message data to be send as response data for the current forwarded RPMI request message. The N represents the total number of bytes in the response data which can be inferred by the platform microcontroller (or SBI implementation) from the overall size of the REQFWD_COMPLETE_CURRENT_MESSAGE service message.

Table 8. Response Data

Word	Name	Type	Description
0	STATUS	int32	Return error code Error Code Description RPMI_SUCCESS Service completed successfully. RPMI_ERR_NO_DATA No forwarded RPMI request message available. Other errors [table_error_codes]