fcd88356db
In the early days of TinyGo, the idea of `postinit` was to enable interrupts only after initializers have run. Which kind of makes sense... except that `time.Sleep` is allowed in init code and `time.Sleep` requires interrupts to be enabled. Therefore, interrupts must be enabled while initializers are being run. This commit simply moves the enabling of interrupts to a point right before running package initializers. It also removes `runtime.postinit`, which is not necessary anymore (and was only used on AVR).
135 строки
3,5 КиБ
Go
135 строки
3,5 КиБ
Go
// +build nrf
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package runtime
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import (
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"device/arm"
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"device/nrf"
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"machine"
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"runtime/interrupt"
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"runtime/volatile"
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)
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type timeUnit int64
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//go:linkname systemInit SystemInit
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func systemInit()
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//export Reset_Handler
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func main() {
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if nrf.FPUPresent {
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arm.SCB.CPACR.Set(0) // disable FPU if it is enabled
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}
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systemInit()
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preinit()
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run()
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exit(0)
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}
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func init() {
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machine.Serial.Configure(machine.UARTConfig{})
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initLFCLK()
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initRTC()
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}
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func initLFCLK() {
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if machine.HasLowFrequencyCrystal {
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nrf.CLOCK.LFCLKSRC.Set(nrf.CLOCK_LFCLKSTAT_SRC_Xtal)
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}
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nrf.CLOCK.TASKS_LFCLKSTART.Set(1)
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for nrf.CLOCK.EVENTS_LFCLKSTARTED.Get() == 0 {
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}
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nrf.CLOCK.EVENTS_LFCLKSTARTED.Set(0)
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}
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func initRTC() {
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nrf.RTC1.TASKS_START.Set(1)
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intr := interrupt.New(nrf.IRQ_RTC1, func(intr interrupt.Interrupt) {
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if nrf.RTC1.EVENTS_COMPARE[0].Get() != 0 {
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nrf.RTC1.EVENTS_COMPARE[0].Set(0)
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nrf.RTC1.INTENCLR.Set(nrf.RTC_INTENSET_COMPARE0)
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nrf.RTC1.EVENTS_COMPARE[0].Set(0)
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rtc_wakeup.Set(1)
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}
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if nrf.RTC1.EVENTS_OVRFLW.Get() != 0 {
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nrf.RTC1.EVENTS_OVRFLW.Set(0)
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rtcOverflows.Set(rtcOverflows.Get() + 1)
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}
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})
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nrf.RTC1.INTENSET.Set(nrf.RTC_INTENSET_OVRFLW)
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intr.SetPriority(0xc0) // low priority
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intr.Enable()
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}
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func putchar(c byte) {
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machine.Serial.WriteByte(c)
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}
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func sleepTicks(d timeUnit) {
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for d != 0 {
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ticks := uint32(d) & 0x7fffff // 23 bits (to be on the safe side)
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rtc_sleep(ticks)
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d -= timeUnit(ticks)
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}
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}
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var rtcOverflows volatile.Register32 // number of times the RTC wrapped around
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// ticksToNanoseconds converts RTC ticks (at 32768Hz) to nanoseconds.
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func ticksToNanoseconds(ticks timeUnit) int64 {
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// The following calculation is actually the following, but with both sides
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// reduced to reduce the risk of overflow:
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// ticks * 1e9 / 32768
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return int64(ticks) * 1953125 / 64
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}
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// nanosecondsToTicks converts nanoseconds to RTC ticks (running at 32768Hz).
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func nanosecondsToTicks(ns int64) timeUnit {
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// The following calculation is actually the following, but with both sides
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// reduced to reduce the risk of overflow:
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// ns * 32768 / 1e9
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return timeUnit(ns * 64 / 1953125)
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}
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// Monotonically increasing numer of ticks since start.
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func ticks() timeUnit {
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// For some ways of capturing the time atomically, see this thread:
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// https://www.eevblog.com/forum/microcontrollers/correct-timing-by-timer-overflow-count/msg749617/#msg749617
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// Here, instead of re-reading the counter register if an overflow has been
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// detected, we simply try again because that results in (slightly) smaller
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// code and is perhaps easier to prove correct.
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for {
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mask := interrupt.Disable()
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counter := uint32(nrf.RTC1.COUNTER.Get())
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overflows := rtcOverflows.Get()
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hasOverflow := nrf.RTC1.EVENTS_OVRFLW.Get() != 0
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interrupt.Restore(mask)
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if hasOverflow {
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// There was an overflow. Try again.
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continue
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}
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// The counter is 24 bits in size, so the number of overflows form the
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// upper 32 bits (together 56 bits, which covers 71493 years at
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// 32768kHz: I'd argue good enough for most purposes).
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return timeUnit(overflows)<<24 + timeUnit(counter)
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}
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}
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var rtc_wakeup volatile.Register8
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func rtc_sleep(ticks uint32) {
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nrf.RTC1.INTENSET.Set(nrf.RTC_INTENSET_COMPARE0)
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rtc_wakeup.Set(0)
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if ticks == 1 {
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// Race condition (even in hardware) at ticks == 1.
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// TODO: fix this in a better way by detecting it, like the manual
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// describes.
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ticks = 2
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}
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nrf.RTC1.CC[0].Set((nrf.RTC1.COUNTER.Get() + ticks) & 0x00ffffff)
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for rtc_wakeup.Get() == 0 {
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waitForEvents()
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}
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}
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