Hi Thomas & Jason, I'm dealing with an interesting situation which I'm wondering if Linux already support for. Basically, in some TI SoCs we have what's referred to as Programmable Real-Time Unit SubSystem (PRUSS). That's essentially a really simple, low latency, single cycle architecture which is pretty darn good for bit banging peripherals (ETH, SPI, I2C, UART, etc). It's very predicatable because every instruction takes 5ns and interrupts don't cause exceptions, they just get registered. Anyway, the interesting part is that PRUSS has 64 events (on current incarnations at least) and PRUSS has 10 physical IRQ lines to the ARM land. Each of these 64 events can be routed to any of these 10 IRQ lines. This might not be very useful on UP (AM335x & AM437x) other than the fact that soft-IP drivers running on Linux would need to guarantee they are the ones who should handle the IRQ. However, on SMP (AM57xx) we could have real tangible benefits by means of IRQ affinity, etc. So, the question is, what is there in IRQ subsystem today for routable IRQ support ? If a Diagram helps here's a simple one. Note that I'm not showing details on the PRUSS side, but that side can also map events pretty much any way it wants. .--------------------. .--------------------. | HOST CPU | | PRUSS | |--------------------| |--------------------| | | | | | irq0 |<-.----------|evt0 | | | | | | | irq1 | | .-------|evt1 | | | | | | | | irq2 | '----------|evt2 | | | | | | | irq3 | | | | | | | | | | irq4 | | | . | | | | | | | irq5 | | | . | | | | | | | irq6 | | | . | | | | | | | irq7 |<----' | | | | | | | irq8 | | | | | | | | irq9 |<------------|evtN | '--------------------' '--------------------' Given this setup, what I want to do, is let soft-IP drivers running on linux rely on standard *request_*irq() calls and DTS descrition. But I'm still considering how/if we should describe the routing itself or just go round-robin (i.o.w. irq0 -> evt0, irq1 -> evt1, ..., irq9 -> evt9, irq0 -> evt10, ...). Thoughts ? -- balbi
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