@startuml
skinparam ParticipantPadding 10
skinparam BoxPadding 10
box RSS
participant RSS_BL1_1
participant RSS_BL1_2
participant RSS_BL2
participant RSS_S
endbox
box SCP
participant SCP_BL1
endbox
box AP
participant AP_BL1
participant AP_BL2
participant AP_BL31
endbox

== RSS Boot phase ==
-> RSS_BL1_1: Reset
Rnote over RSS_BL1_1: ROM code, XIP
Rnote over RSS_BL1_2: OTP code, XIP
Rnote over RSS_BL2, AP_BL31: Stored in flash, loaded and executed in RAM
activate RSS_BL1_1 #Green
RSS_BL1_1 -->> RSS_BL1_2: Validate, measure
Rnote over RSS_BL1_1: BL1_2 measurement\n\ saved to a shared buffer
RSS_BL1_1 -> RSS_BL1_2: Pass execution
deactivate RSS_BL1_1
activate RSS_BL1_2 #Green
RSS_BL1_2 -->> RSS_BL2: Validate, measure, load
Rnote over RSS_BL1_2: RSS_BL2 measurement\n\ saved to a shared buffer
RSS_BL1_2 -> RSS_BL2: Pass execution
deactivate RSS_BL1_2
activate RSS_BL2 #Green
RSS_BL2 -->> RSS_S: Validate, measure, load
RSS_BL2 -->> SCP_BL1: Validate, measure, load
Rnote over RSS_BL2: RSS_S and SCP_BL1\n\ measurements saved\n\ to a shared buffer
RSS_BL2 -> SCP_BL1: Release from reset
activate SCP_BL1 #Green
Rnote over RSS_BL2, SCP_BL1: MHU init between RSS and SCP
Rnote over SCP_BL1: Configure memory
Rnote over RSS_BL2: Waits for SCP
SCP_BL1 --> RSS_BL2: Done
RSS_BL2 -->> AP_BL1: Validate, measure, load
Rnote over RSS_BL2: AP_BL1 measurement\n\ saved to a shared buffer
RSS_BL2 -> AP_BL1: Release from reset
activate AP_BL1 #Green
RSS_BL2 -> RSS_S: Pass execution
deactivate RSS_BL2
activate RSS_S #Green
Rnote over RSS_S: Measurements read from\n\ shared buffer and saved by\n\
Measured Boot service to\n\ measurement slots.

== RSS Runtime / AP Boot phase ==
Rnote over RSS_S, AP_BL1: MHU init between RSS and AP
Rnote over AP_BL1: Measure and load:\n\ FW_CONFIG\n\ TB_FW_CONFIG
AP_BL1 -> RSS_S: Extend measurement
Rnote over RSS_S: Measured Boot:\n\ store measurement
AP_BL1 -->> AP_BL2: Validate, measure,load
AP_BL1 -> RSS_S: Extend measurement
Rnote over RSS_S: Measured Boot:\n\ store measurement
AP_BL1 -> AP_BL2: Pass execution
deactivate AP_BL1
activate AP_BL2 #Green
Rnote over AP_BL2: Measure and load:\n\ HW_CONFIG
AP_BL2 -> RSS_S: Extend measurement
Rnote over RSS_S: Measured Boot:\n\ store measurement
AP_BL2 -->> AP_BL31: Validate, measure,load
Rnote over AP_BL2: Measure and load:\n\ BL31
AP_BL2 -> RSS_S: Extend measurement
Rnote over RSS_S: Measured Boot:\n\ store measurement
Rnote over AP_BL2: Measure and load:\n\ RMM
AP_BL2 -> RSS_S: Extend measurement
Rnote over RSS_S: Measured Boot:\n\ store measurement
AP_BL2 -> AP_BL31: Pass execution
deactivate AP_BL2
activate AP_BL31 #Green
== RSS / AP Runtime ==
@enduml