Add Clock trait

embassy-nrf/src/rtc.rs

@@ -2,6 +2,8 @@ use core::cell::Cell;
 use core::ops::Deref;
 use core::sync::atomic::{AtomicU32, Ordering};
 
+use embassy::time::Clock;
+
 use crate::interrupt;
 use crate::interrupt::{CriticalSection, Mutex};
 use crate::pac::{rtc0, Interrupt, RTC0, RTC1};
@@ -100,12 +102,6 @@ impl<T: Instance> RTC<T> {
         interrupt::enable(T::INTERRUPT);
     }
 
-    pub fn now(&self) -> u64 {
-        let counter = self.rtc.counter.read().bits();
-        let period = self.period.load(Ordering::Relaxed);
-        calc_now(period, counter)
-    }
-
     fn on_interrupt(&self) {
         if self.rtc.events_ovrflw.read().bits() == 1 {
             self.rtc.events_ovrflw.write(|w| w);
@@ -203,6 +199,14 @@ impl<T: Instance> RTC<T> {
     }
 }
 
+impl<T: Instance> embassy::time::Clock for RTC<T> {
+    fn now(&self) -> u64 {
+        let counter = self.rtc.counter.read().bits();
+        let period = self.period.load(Ordering::Relaxed);
+        calc_now(period, counter)
+    }
+}
+
 pub struct Alarm<T: Instance> {
     n: usize,
     rtc: &'static RTC<T>,

embassy/src/time.rs

@@ -7,21 +7,17 @@ use core::ptr;
 use core::sync::atomic::{AtomicPtr, Ordering};
 use core::task::{Context, Poll};
 
+use crate::util::*;
 use fi::LocalTimer;
 use futures_intrusive::timer as fi;
+static mut CLOCK: Option<&'static dyn Clock> = None;
 
-static mut CLOCK: fn() -> u64 = clock_not_set;
-
-fn clock_not_set() -> u64 {
-    panic!("No clock set. You must call embassy::time::set_clock() before trying to use the clock")
-}
-
-pub unsafe fn set_clock(clock: fn() -> u64) {
-    CLOCK = clock;
+pub unsafe fn set_clock(clock: &'static dyn Clock) {
+    CLOCK = Some(clock);
 }
 
 fn now() -> u64 {
-    unsafe { CLOCK() }
+    unsafe { CLOCK.dexpect(defmt::intern!("No clock set")).now() }
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
@@ -270,6 +266,19 @@ impl Future for Timer {
         unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().inner) }.poll(cx)
     }
 }
+/// Monotonic clock
+pub trait Clock {
+    /// Return the current timestamp in ticks.
+    /// This is guaranteed to be monotonic, i.e. a call to now() will always return
+    /// a greater or equal value than earler calls.
+    fn now(&self) -> u64;
+}
+
+impl<T: Clock + ?Sized> Clock for &T {
+    fn now(&self) -> u64 {
+        T::now(self)
+    }
+}
 
 /// Trait to register a callback at a given timestamp.
 pub trait Alarm {
@@ -289,3 +298,15 @@ pub trait Alarm {
     /// If no alarm was set, this is a noop.
     fn clear(&self);
 }
+
+impl<T: Alarm + ?Sized> Alarm for &T {
+    fn set_callback(&self, callback: fn()) {
+        T::set_callback(self, callback);
+    }
+    fn set(&self, timestamp: u64) {
+        T::set(self, timestamp);
+    }
+    fn clear(&self) {
+        T::clear(self)
+    }
+}

embassy/src/util/mod.rs

@@ -11,7 +11,7 @@ pub use waker_store::*;
 mod drop_bomb;
 pub use drop_bomb::*;
 
-use defmt::{warn, error};
+use defmt::{debug, error, info, intern, trace, warn};
 
 pub trait Dewrap<T> {
     /// dewrap = defmt unwrap

examples/src/bin/rtc_async.rs

@@ -9,7 +9,7 @@ use example_common::*;
 use core::mem::MaybeUninit;
 use cortex_m_rt::entry;
 use embassy::executor::{task, Executor, WfeModel};
-use embassy::time::{Duration, Instant, Timer};
+use embassy::time::{Clock, Duration, Timer};
 use embassy_nrf::pac;
 use embassy_nrf::rtc;
 use nrf52840_hal::clocks;
@@ -51,7 +51,7 @@ fn main() -> ! {
     };
 
     rtc.start();
-    unsafe { embassy::time::set_clock(|| RTC.as_ptr().as_ref().unwrap().now()) };
+    unsafe { embassy::time::set_clock(rtc) };
 
     let executor: &'static _ = unsafe {
         let ptr = EXECUTOR.as_mut_ptr();

examples/src/bin/rtc_raw.rs

@@ -8,7 +8,7 @@ use example_common::*;
 
 use core::mem::MaybeUninit;
 use cortex_m_rt::entry;
-use embassy::time::Alarm;
+use embassy::time::{Alarm, Clock};
 use embassy_nrf::rtc;
 use nrf52840_hal::clocks;