Hi Yann,
You are right, the RSE comms is basically a custom RPC protocol between the application processor and RSE which is coupled with MHUs (acting as the data link layer). The RSE comms sounds like it’s specific to this platform component (RSE) but the protocol itself could be extended to other platforms as well I believe. The platform dependency here is the MHU, how the data is transferred.
Your approach could work, adding an extra data layer between the abstract MHU communication (include/drivers/arm/mhu.h) and the RSE comms protocol – hiding the platform specifics of the data transfer. However, setting PLAT_MHU_VERSION to 0 would be misleading to some extent I think. I would rather introduce a new build option for clarity.
What others think?
Regards, David
From: Olivier Deprez Olivier.Deprez@arm.com Date: Monday, 23 September 2024 at 14:14 To: tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org, Yann Gautier yann.gautier@foss.st.com Cc: Tamas Ban Tamas.Ban@arm.com, Raef Coles Raef.Coles@arm.com, David Vincze David.Vincze@arm.com, Manish Badarkhe Manish.Badarkhe@arm.com Subject: Re: [TF-A] PSA calls with RSE comms and MHU +few stakeholders in Cc
________________________________ From: Yann Gautier via TF-A tf-a@lists.trustedfirmware.org Sent: 23 September 2024 11:28 To: tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org Subject: [TF-A] PSA calls with RSE comms and MHU
Hello,
I would like to use PSA calls for an application on STM32MP2 platform. I've seen the psa_call() API that I could use, in drivers/arm/rse/rse_comms.c.
The problem is that it is based on MHU mailbox, which I don't have on STM32MP2. So I was planning plan to disentangle RSE comms and MHU, having a new file in the same directory to manage MHU. This code should then be under a flag, I could re-use PLAT_MHU_VERSION. Setting it to 0, would mean no MHU.
AFAICT TF-M uses that split with a dedicated file: rse_comms_hal.c: Abstracts MHU message sending and receiving. (see https://tf-m-user-guide.trustedfirmware.org/platform/arm/rse/rse_comms.html).
Do you think this approach sounds right?
Thanks, Yann -- TF-A mailing list -- tf-a@lists.trustedfirmware.org To unsubscribe send an email to tf-a-leave@lists.trustedfirmware.org