/'
 ' Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
 '
 ' SPDX-License-Identifier: BSD-3-Clause
 '/

@startuml

autonumber "<b>[#]</b>"
participant "SDEI client" as EL2
participant EL3
participant "Secure Partition" as SP

activate EL2
EL2->EL3: **SDEI_EVENT_REGISTER**(ev, handler, ...)
EL3->EL2: success
EL2->EL3: **SDEI_EVENT_ENABLE**(ev)
EL3->EL2: success
EL2->EL3: **SDEI_PE_UNMASK**()
EL3->EL2: 1

... <<Business as usual>> ...

EL3<--]: **CRITICAL EVENT**
activate EL3 #red
note over EL3: Critical event triage
EL3->SP: dispatch
activate SP #salmon
note over SP: Critical event handling
SP->EL3: done
deactivate SP
EL3-->EL3: sdei_dispatch_event(ev)
note over EL3: Prepare SDEI dispatch
EL3->EL2: dispatch
activate EL2 #salmon
note over EL2: SDEI handler
EL2->EL3: **SDEI_EVENT_COMPLETE()**
deactivate EL2
note over EL3: Complete SDEI dispatch
EL3->EL2: resumes preempted execution
deactivate EL3

... <<Normal execution resumes>> ...

@enduml