2020-10-22 Meeting notes
Date
Oct 22, 2020
Attendees
@Vincent Guittot
@Former user (Deleted)
@Souvik Chakravarty
@Former user (Deleted)
@Bill Fletcher
@Lionel Debieve (Deactivated)
Summary
How to handle interrupt and more generally speaking asynchronous event in SCMI server in OP-TEE ?
OP-TEE interrupt handling and OP-TEE thread context can't interact directly: interrupt can't start or wake up a thread context. Thread contexts are only executed based on a non secure world invocation
The proposal is to let linux to handle the HW interrupt and send a proprietary scmi message using OEM/ODM range
message content from linux to SCP firmware will be as simple as the irq number. A module in SCP firmware will then put an event for the targeted module (like i2c, sensor) to handle the event
Studied and started to work on this on fvp. Wanted to use sensor scmi notification for the PoC
SCMI sensor notification in SCP firmware should be available in few weeks
Letting Linux to handle interrupt and forward the asynchronous event to SCMI server is acceptable only for none critical event that can't impact the integrity of the system (unlike reaching max Tj ). In the latter case OP-TEE must catch the critical event and act accordingly (like resetting or powering down the system). So we could have to share the interrupt between secure and non secure. OP-TEE will check if the interrupt is raised because of a critical event and linux will take care of non critical events
forwarding the HW interrupt from optee to non secure might not be possible
using one SPI for secure world to trigger non secure interrupt
Ruchika : add an action to look if SWG can do something about enabling interaction between interrupt and thread context
new scmi patchset on linux
1st patchset about clean up and supporting OEM protocol
vincent to review them next week
2nd patchset voltage regulator
etienne reviewed and tested it
Round table
Souvik : About SCMI specification v3
End Of October: comment acceptance closed
Release of scmi v3 targeted for end of november
Etienne : how to move forward on merging SCP code into OP-TEE ?
we need to define an Execution Environment Interface which is architecture independent on which OP-TEE interface can be attached. And also other execution environnement
Is optee compatible with some posix interface ? No
Need to look at other "OS" like
zephyr or TFA SEL0 to define a generic i/f
running in a secure partition. Sidenote: 1st step will be to use optee to handle SEL0 before moving on hafnium
Starting comparison about which interfaces from different Execution environment
Optee: Etienne
zephyr: Souvik
SEL0 TFA: Ruchika to point some documents. Interface should be same as FFA