protocol: Provide abstraction over event notification

How this works will be transport-dependent. Move the event notification
helpers into the protocol abstraction and call-back through the
registered flush handler as necessary.

Change-Id: I29e3a9a9785b92de46a2b2750257fb7f8480a184
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/protocol.h b/protocol.h
index 5cdc2eb..f2b8e6f 100644
--- a/protocol.h
+++ b/protocol.h
@@ -120,6 +120,14 @@
 
 int protocol_negotiate_version(struct mbox_context *context, uint8_t requested);
 
+#define EVENT_SUPPRESS		false
+#define EVENT_TRIGGER		true
+
+int protocol_events_set(struct mbox_context *context, uint8_t bmc_event,
+			bool write_back);
+int protocol_events_clear(struct mbox_context *context, uint8_t bmc_event,
+			  bool write_back);
+
 /* Protocol v1 */
 int protocol_v1_reset(struct mbox_context *context);
 int protocol_v1_get_info(struct mbox_context *context,