runtime/rp2: handle RP2350 shared FIFO IRQ for GC (#5482)

* runtime/rp2: handle RP2350 shared FIFO IRQ for GC

---------

Co-authored-by: rdon <you@example.com>

src/runtime/runtime_rp2040.go

@@ -4,9 +4,39 @@ package runtime
 
 import (
 	"device/rp"
+	"runtime/interrupt"
 )
 
 const (
 	sioIrqFifoProc0 = rp.IRQ_SIO_IRQ_PROC0
 	sioIrqFifoProc1 = rp.IRQ_SIO_IRQ_PROC1
 )
+
+// On RP2040, each core has its own SIO FIFO IRQ. Core0 enables
+// IRQ_SIO_IRQ_PROC0 and Core1 enables IRQ_SIO_IRQ_PROC1, so each handler can
+// use a fixed core ID.
+func enableSIOFifoInterruptCore0() {
+	intr := interrupt.New(sioIrqFifoProc0, handleSIOFifoInterruptCore0)
+	intr.Enable()
+	intr.SetPriority(0xff)
+}
+
+func enableSIOFifoInterruptCore1() {
+	intr := interrupt.New(sioIrqFifoProc1, handleSIOFifoInterruptCore1)
+	intr.Enable()
+	intr.SetPriority(0xff)
+}
+
+func handleSIOFifoInterruptCore0(intr interrupt.Interrupt) {
+	switch rp.SIO.FIFO_RD.Get() {
+	case 1:
+		gcInterruptHandler(0)
+	}
+}
+
+func handleSIOFifoInterruptCore1(intr interrupt.Interrupt) {
+	switch rp.SIO.FIFO_RD.Get() {
+	case 1:
+		gcInterruptHandler(1)
+	}
+}