machine/rp2040: add interrupt API

src/machine/machine_rp2040_sync.go

@@ -0,0 +1,73 @@
+//go:build rp2040
+// +build rp2040
+
+package machine
+
+import (
+	"device/rp"
+)
+
+// machine_rp2040_sync.go contains interrupt and
+// lock primitives similar to those found in Pico SDK's
+// irq.c
+
+const (
+	// Number of spin locks available
+	_NUMSPINLOCKS = 32
+	// Number of interrupt handlers available
+	_NUMIRQ               = 32
+	_PICO_SPINLOCK_ID_IRQ = 9
+	_NUMBANK0_GPIOS       = 30
+)
+
+// Clears interrupt flag on a pin
+func (p Pin) acknowledgeInterrupt(change PinChange) {
+	ioBank0.intR[p>>3].Set(p.ioIntBit(change))
+}
+
+// Basic interrupt setting via ioBANK0 for GPIO interrupts.
+func (p Pin) setInterrupt(change PinChange, enabled bool) {
+	// Separate mask/force/status per-core, so check which core called, and
+	// set the relevant IRQ controls.
+	switch CurrentCore() {
+	case 0:
+		p.ctrlSetInterrupt(change, enabled, &ioBank0.proc0IRQctrl)
+	case 1:
+		p.ctrlSetInterrupt(change, enabled, &ioBank0.proc1IRQctrl)
+	}
+}
+
+// ctrlSetInterrupt acknowledges any pending interrupt and enables or disables
+// the interrupt for a given IRQ control bank (IOBANK, DormantIRQ, QSPI).
+//
+// pico-sdk calls this the _gpio_set_irq_enabled, not to be confused with
+// gpio_set_irq_enabled (no leading underscore).
+func (p Pin) ctrlSetInterrupt(change PinChange, enabled bool, base *irqCtrl) {
+	p.acknowledgeInterrupt(change)
+	enReg := &base.intE[p>>3]
+	if enabled {
+		enReg.SetBits(p.ioIntBit(change))
+	} else {
+		enReg.ClearBits(p.ioIntBit(change))
+	}
+}
+
+// Enable or disable a specific interrupt on the executing core.
+// num is the interrupt number which must be in [0,31].
+func irqSet(num uint32, enabled bool) {
+	if num >= _NUMIRQ {
+		return
+	}
+	irqSetMask(1<<num, enabled)
+}
+
+func irqSetMask(mask uint32, enabled bool) {
+	if enabled {
+		// Clear pending before enable
+		// (if IRQ is actually asserted, it will immediately re-pend)
+		rp.PPB.NVIC_ICPR.Set(mask)
+		rp.PPB.NVIC_ISER.Set(mask)
+	} else {
+		rp.PPB.NVIC_ICER.Set(mask)
+	}
+}