Merge pull request #382 from fnafnio/typestate_nrf_timer

Typestate nrf timer

4 files changed, 103 insertions, 49 deletions

diff --git a/embassy-nrf/src/buffered_uarte.rs b/embassy-nrf/src/buffered_uarte.rs
index 048c36d39..90ce49582 100644
--- a/embassy-nrf/src/buffered_uarte.rs
+++ b/embassy-nrf/src/buffered_uarte.rs
@@ -15,9 +15,8 @@ use crate::gpio::sealed::Pin as _;
 use crate::gpio::{OptionalPin as GpioOptionalPin, Pin as GpioPin};
 use crate::pac;
 use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
-use crate::timer::Frequency;
 use crate::timer::Instance as TimerInstance;
-use crate::timer::Timer;
+use crate::timer::{Frequency, Timer};
 use crate::uarte::{Config, Instance as UarteInstance};
 
 // Re-export SVD variants to allow user to directly set values
@@ -85,7 +84,7 @@ impl<'d, U: UarteInstance, T: TimerInstance> BufferedUarte<'d, U, T> {
 
         let r = U::regs();
 
-        let mut timer = Timer::new_irqless(timer);
+        let mut timer = Timer::new(timer);
 
         rxd.conf().write(|w| w.input().connect().drive().h0h1());
         r.psel.rxd.write(|w| unsafe { w.bits(rxd.psel_bits()) });
diff --git a/embassy-nrf/src/timer.rs b/embassy-nrf/src/timer.rs
index eab9a1416..638fd8229 100644
--- a/embassy-nrf/src/timer.rs
+++ b/embassy-nrf/src/timer.rs
@@ -27,6 +27,8 @@ pub(crate) mod sealed {
         fn waker(n: usize) -> &'static AtomicWaker;
     }
     pub trait ExtendedInstance {}
+
+    pub trait TimerType {}
 }
 
 pub trait Instance: Unborrow<Target = Self> + sealed::Instance + 'static + Send {
@@ -84,12 +86,23 @@ pub enum Frequency {
 ///
 /// It has either 4 or 6 Capture/Compare registers, which can be used to capture the current state of the counter
 /// or trigger an event when the counter reaches a certain value.
-pub struct Timer<'d, T: Instance> {
-    phantom: PhantomData<&'d mut T>,
+
+pub trait TimerType: sealed::TimerType {}
+
+pub enum Awaitable {}
+pub enum NotAwaitable {}
+
+impl sealed::TimerType for Awaitable {}
+impl sealed::TimerType for NotAwaitable {}
+impl TimerType for Awaitable {}
+impl TimerType for NotAwaitable {}
+
+pub struct Timer<'d, T: Instance, I: TimerType = NotAwaitable> {
+    phantom: PhantomData<(&'d mut T, I)>,
 }
 
-impl<'d, T: Instance> Timer<'d, T> {
-    pub fn new(
+impl<'d, T: Instance> Timer<'d, T, Awaitable> {
+    pub fn new_awaitable(
         timer: impl Unborrow<Target = T> + 'd,
         irq: impl Unborrow<Target = T::Interrupt> + 'd,
     ) -> Self {
@@ -101,11 +114,22 @@ impl<'d, T: Instance> Timer<'d, T> {
 
         Self::new_irqless(timer)
     }
+}
+impl<'d, T: Instance> Timer<'d, T, NotAwaitable> {
+    /// Create a `Timer` without an interrupt, meaning `Cc::wait` won't work.
+    ///
+    /// This can be useful for triggering tasks via PPI
+    /// `Uarte` uses this internally.
+    pub fn new(timer: impl Unborrow<Target = T> + 'd) -> Self {
+        Self::new_irqless(timer)
+    }
+}
 
+impl<'d, T: Instance, I: TimerType> Timer<'d, T, I> {
     /// Create a `Timer` without an interrupt, meaning `Cc::wait` won't work.
     ///
-    /// This is used by `Uarte` internally.
-    pub(crate) fn new_irqless(_timer: impl Unborrow<Target = T> + 'd) -> Self {
+    /// This is used by the public constructors.
+    fn new_irqless(_timer: impl Unborrow<Target = T> + 'd) -> Self {
         let regs = T::regs();
 
         let mut this = Self {
@@ -208,7 +232,7 @@ impl<'d, T: Instance> Timer<'d, T> {
     ///
     /// # Panics
     /// Panics if `n` >= the number of CC registers this timer has (4 for a normal timer, 6 for an extended timer).
-    pub fn cc(&mut self, n: usize) -> Cc<T> {
+    pub fn cc(&mut self, n: usize) -> Cc<T, I> {
         if n >= T::CCS {
             panic!(
                 "Cannot get CC register {} of timer with {} CC registers.",
@@ -230,12 +254,48 @@ impl<'d, T: Instance> Timer<'d, T> {
 ///
 /// The timer will fire the register's COMPARE event when its counter reaches the value stored in the register.
 /// When the register's CAPTURE task is triggered, the timer will store the current value of its counter in the register
-pub struct Cc<'a, T: Instance> {
+pub struct Cc<'a, T: Instance, I: TimerType = NotAwaitable> {
     n: usize,
-    phantom: PhantomData<&'a mut T>,
+    phantom: PhantomData<(&'a mut T, I)>,
+}
+
+impl<'a, T: Instance> Cc<'a, T, Awaitable> {
+    /// Wait until the timer's counter reaches the value stored in this register.
+    ///
+    /// This requires a mutable reference so that this task's waker cannot be overwritten by a second call to `wait`.
+    pub async fn wait(&mut self) {
+        let regs = T::regs();
+
+        // Enable the interrupt for this CC's COMPARE event.
+        regs.intenset
+            .modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
+
+        // Disable the interrupt if the future is dropped.
+        let on_drop = OnDrop::new(|| {
+            regs.intenclr
+                .modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
+        });
+
+        poll_fn(|cx| {
+            T::waker(self.n).register(cx.waker());
+
+            if regs.events_compare[self.n].read().bits() != 0 {
+                // Reset the register for next time
+                regs.events_compare[self.n].reset();
+                Poll::Ready(())
+            } else {
+                Poll::Pending
+            }
+        })
+        .await;
+
+        // The interrupt was already disabled in the interrupt handler, so there's no need to disable it again.
+        on_drop.defuse();
+    }
 }
+impl<'a, T: Instance> Cc<'a, T, NotAwaitable> {}
 
-impl<'a, T: Instance> Cc<'a, T> {
+impl<'a, T: Instance, I: TimerType> Cc<'a, T, I> {
     /// Get the current value stored in the register.
     pub fn read(&self) -> u32 {
         T::regs().cc[self.n].read().cc().bits()
@@ -304,37 +364,4 @@ impl<'a, T: Instance> Cc<'a, T> {
             .shorts
             .modify(|r, w| unsafe { w.bits(r.bits() & !(1 << (8 + self.n))) })
     }
-
-    /// Wait until the timer's counter reaches the value stored in this register.
-    ///
-    /// This requires a mutable reference so that this task's waker cannot be overwritten by a second call to `wait`.
-    pub async fn wait(&mut self) {
-        let regs = T::regs();
-
-        // Enable the interrupt for this CC's COMPARE event.
-        regs.intenset
-            .modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
-
-        // Disable the interrupt if the future is dropped.
-        let on_drop = OnDrop::new(|| {
-            regs.intenclr
-                .modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
-        });
-
-        poll_fn(|cx| {
-            T::waker(self.n).register(cx.waker());
-
-            if regs.events_compare[self.n].read().bits() != 0 {
-                // Reset the register for next time
-                regs.events_compare[self.n].reset();
-                Poll::Ready(())
-            } else {
-                Poll::Pending
-            }
-        })
-        .await;
-
-        // The interrupt was already disabled in the interrupt handler, so there's no need to disable it again.
-        on_drop.defuse();
-    }
 }
diff --git a/embassy-nrf/src/uarte.rs b/embassy-nrf/src/uarte.rs
index b2b298661..a6909be68 100644
--- a/embassy-nrf/src/uarte.rs
+++ b/embassy-nrf/src/uarte.rs
@@ -18,9 +18,8 @@ use crate::gpio::{self, OptionalPin as GpioOptionalPin, Pin as GpioPin};
 use crate::interrupt::Interrupt;
 use crate::pac;
 use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
-use crate::timer::Frequency;
 use crate::timer::Instance as TimerInstance;
-use crate::timer::Timer;
+use crate::timer::{Frequency, Timer};
 
 // Re-export SVD variants to allow user to directly set values.
 pub use pac::uarte0::{baudrate::BAUDRATE_A as Baudrate, config::PARITY_A as Parity};
@@ -318,7 +317,7 @@ impl<'d, U: Instance, T: TimerInstance> UarteWithIdle<'d, U, T> {
     ) -> Self {
         let baudrate = config.baudrate;
         let uarte = Uarte::new(uarte, irq, rxd, txd, cts, rts, config);
-        let mut timer = Timer::new_irqless(timer);
+        let mut timer = Timer::new(timer);
 
         unborrow!(ppi_ch1, ppi_ch2);
 
diff --git a/examples/nrf/src/bin/awaitable_timer.rs b/examples/nrf/src/bin/awaitable_timer.rs
new file mode 100644
index 000000000..289a33c71
--- /dev/null
+++ b/examples/nrf/src/bin/awaitable_timer.rs
@@ -0,0 +1,29 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use embassy_nrf::interrupt;
+use embassy_nrf::timer::Timer;
+use embassy_nrf::Peripherals;
+use example_common::info;
+
+use embassy::executor::Spawner;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    let mut t = Timer::new_awaitable(p.TIMER0, interrupt::take!(TIMER0));
+    // default frequency is 1MHz, so this triggers every second
+    t.cc(0).write(1_000_000);
+    // clear the timer value on cc[0] compare match
+    t.cc(0).short_compare_clear();
+    t.start();
+
+    loop {
+        // wait for compare match
+        t.cc(0).wait().await;
+        info!("hardware timer tick");
+    }
+}