WIP: interrupt API

src/runtime/interrupt/interrupt.go

@@ -0,0 +1,25 @@
+// Package interrupt provides access to hardware interrupts. It provides a way
+// to define interrupts and to enable/disable them.
+package interrupt
+
+// Interrupt provides direct access to hardware interrupts. You can configure
+// this interrupt through this interface.
+//
+// Do not use the zero value of an Interrupt object. Instead, call New to obtain
+// an interrupt handle.
+type Interrupt struct {
+	// Make this number unexported so it cannot be set directly. This provides
+	// some encapsulation.
+	num int
+}
+
+// New is a compiler intrinsic that creates a new Interrupt object. You may call
+// it only once, and must pass constant parameters to it. That means that the
+// interrupt ID must be a Go constant and that the handler must be a simple
+// function: closures are not supported.
+func New(id int, handler func(Interrupt)) Interrupt
+
+// Register is used to declare an interrupt. You should not normally call this
+// function: it is only for telling the compiler about the mapping between an
+// interrupt number and the interrupt handler name.
+func Register(id int, handlerName string) int

src/runtime/interrupt/interrupt_cortexm.go

@@ -0,0 +1,23 @@
+// +build cortexm
+
+package interrupt
+
+import (
+	"device/arm"
+)
+
+// Enable enables this interrupt. Right after calling this function, the
+// interrupt may be invoked if it was already pending.
+func (irq Interrupt) Enable() {
+	arm.EnableIRQ(uint32(irq.num))
+}
+
+// SetPriority sets the interrupt priority for this interrupt. A lower number
+// means a higher priority. Additionally, most hardware doesn't implement all
+// priority bits (only the uppoer bits).
+//
+// Examples: 0xff (lowest priority), 0xc0 (low priority), 0x00 (highest possible
+// priority).
+func (irq Interrupt) SetPriority(priority uint8) {
+	arm.SetPriority(uint32(irq.num), uint32(priority))
+}

src/runtime/runtime_atsamd21.go

@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/sam"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 	"unsafe"
 )
@@ -214,8 +215,14 @@ func initRTC() {
 	sam.RTC_MODE0.CTRL.SetBits(sam.RTC_MODE0_CTRL_ENABLE)
 	waitForSync()
 
-	arm.SetPriority(sam.IRQ_RTC, 0xc0)
-	arm.EnableIRQ(sam.IRQ_RTC)
+	intr := interrupt.New(sam.IRQ_RTC, func(intr interrupt.Interrupt) {
+		// disable IRQ for CMP0 compare
+		sam.RTC_MODE0.INTFLAG.Set(sam.RTC_MODE0_INTENSET_CMP0)
+
+		timerWakeup.Set(1)
+	})
+	intr.SetPriority(0xc0)
+	intr.Enable()
 }
 
 func waitForSync() {
@@ -286,14 +293,6 @@ func timerSleep(ticks uint32) {
 	}
 }
 
-//go:export RTC_IRQHandler
-func handleRTC() {
-	// disable IRQ for CMP0 compare
-	sam.RTC_MODE0.INTFLAG.Set(sam.RTC_MODE0_INTENSET_CMP0)
-
-	timerWakeup.Set(1)
-}
-
 func initUSBClock() {
 	// Turn on clock for USB
 	sam.PM.APBBMASK.SetBits(sam.PM_APBBMASK_USB_)

src/runtime/runtime_nrf.go

@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/nrf"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 )
 
@@ -43,8 +44,13 @@ func initLFCLK() {
 
 func initRTC() {
 	nrf.RTC1.TASKS_START.Set(1)
-	arm.SetPriority(nrf.IRQ_RTC1, 0xc0) // low priority
-	arm.EnableIRQ(nrf.IRQ_RTC1)
+	intr := interrupt.New(nrf.IRQ_RTC1, func(intr interrupt.Interrupt) {
+		nrf.RTC1.INTENCLR.Set(nrf.RTC_INTENSET_COMPARE0)
+		nrf.RTC1.EVENTS_COMPARE[0].Set(0)
+		rtc_wakeup.Set(1)
+	})
+	intr.SetPriority(0xc0) // low priority
+	intr.Enable()
 }
 
 func putchar(c byte) {
@@ -96,10 +102,3 @@ func rtc_sleep(ticks uint32) {
 		arm.Asm("wfi")
 	}
 }
-
-//go:export RTC1_IRQHandler
-func handleRTC1() {
-	nrf.RTC1.INTENCLR.Set(nrf.RTC_INTENSET_COMPARE0)
-	nrf.RTC1.EVENTS_COMPARE[0].Set(0)
-	rtc_wakeup.Set(1)
-}