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Fix race condition in RTC alarm by using AtomicBool flag

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1-rafael-1 2025-09-15 21:57:41 +02:00
parent ac32f43c3d
commit dd10e372d2
1 changed files with 14 additions and 6 deletions
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20
embassy-rp/src/rtc/mod.rs
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@ -2,7 +2,7 @@
mod filter;
use core::future::poll_fn;
use core::sync::atomic::{compiler_fence, Ordering};
use core::sync::atomic::{compiler_fence, AtomicBool, Ordering};
use core::task::Poll;
use embassy_hal_internal::{Peri, PeripheralType};
@ -21,6 +21,8 @@ use crate::interrupt::{self, InterruptExt};
// Static waker for the interrupt handler
static WAKER: AtomicWaker = AtomicWaker::new();
// Static flag to indicate if an alarm has occurred
static ALARM_OCCURRED: AtomicBool = AtomicBool::new(false);
/// A reference to the real time clock of the system
pub struct Rtc<'d, T: Instance> {
@ -257,10 +259,15 @@ impl<'d, T: Instance> Rtc<'d, T> {
poll_fn(|cx| {
WAKER.register(cx.waker());
// Check hardware interrupt status directly
if self.inner.regs().ints().read().rtc() {
// Clear the interrupt status and disable the alarm
self.inner.regs().ints().write(|w| w.set_rtc(true));
// Atomically check and clear the alarm occurred flag to prevent race conditions
if critical_section::with(|_| {
let occurred = ALARM_OCCURRED.load(Ordering::SeqCst);
if occurred {
ALARM_OCCURRED.store(false, Ordering::SeqCst);
}
occurred
}) {
// Clear the interrupt and disable the alarm
self.clear_interrupt();
compiler_fence(Ordering::SeqCst);
@ -284,7 +291,8 @@ impl crate::interrupt::typelevel::Handler<crate::interrupt::typelevel::RTC_IRQ>
let rtc = crate::pac::RTC;
rtc.irq_setup_0().modify(|w| w.set_match_ena(false));
// Wake the waker - interrupt status will be checked directly by polling future
// Set the alarm occurred flag and wake the waker
ALARM_OCCURRED.store(true, Ordering::SeqCst);
WAKER.wake();
}
}