Hi all,

When TF-M RPC callbacks were introduced to support multi-core mailbox handling, typically only a single mailbox interrupt source was available on a multi-core system. Therefore, in the initial design, RPC callback handle_req(void) doesn't pass any information of mailbox interrupt source to platform mailbox drivers.

Recently, some platforms, such as RSE based ones, consists of multiple mailbox interrupt sources. I notice that those platforms fetch and parse mailbox messages in their mailbox IRQ handlers. It can take quite a long time in IRQ handlers and doesn't get full benefits from Second-Level Interrupt Handling. Due to the limitation of RPC callback handle_req(void), those platforms are unable to move mailbox message handling to threaded NS Agent Mailbox SP context.

I'd propose to add a new RPC callback handle_req_irq_src(irq_src) to pass mailbox interrupt source information to platform drivers. With this information, platform drivers can identify the source and select the corresponding handler to fetch, parse and dispatch mailbox messages in NS Agent Mailbox SP context, instead of in IRQ handlers.

If platform owners are all satisfied with this new RPC callback, I also wonder if it can replace the existing handle_req() in future, assumed no backward compatible issues are raised.

Please can you review the patches: https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/34317/1? Any comment is welcome. Thank you.

Best regards, David Hu