embassy-nrf: add gpiote::InputChannel::wait_for_high/low()

Also catch GPIOTE events directly when wait() is called, even before
polling the future.

5 files changed, 77 insertions, 18 deletions

diff --git a/embassy-nrf/CHANGELOG.md b/embassy-nrf/CHANGELOG.md
index a0668c495..98f40f9a9 100644
--- a/embassy-nrf/CHANGELOG.md
+++ b/embassy-nrf/CHANGELOG.md
@@ -22,6 +22,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - bugfix: Do not write to UICR from non-secure code on nrf53
 - bugfix: Add delay to uart init anomaly fix
 - changed: `BufferedUarte::read_ready` now uses the same definition for 'empty' so following read calls will not block when true is returned
+- added: add `gpiote::InputChannel::wait_for_high()` and `wait_for_low()` to wait for specific signal level
+- changed: `gpiote::InputChannel::wait()` now takes a mutable reference to `self` to avoid interference from concurrent calls
+- changed: `gpiote::InputChannel::wait()` now ensures events are seen as soon as the function is called, even if the future is not polled
 
 ## 0.8.0 - 2025-09-30
 
diff --git a/embassy-nrf/src/gpiote.rs b/embassy-nrf/src/gpiote.rs
index 91944d8cd..d4f6668f3 100644
--- a/embassy-nrf/src/gpiote.rs
+++ b/embassy-nrf/src/gpiote.rs
@@ -349,16 +349,73 @@ impl<'d> InputChannel<'d> {
     }
 
     /// Asynchronously wait for an event in this channel.
-    pub async fn wait(&self) {
-        let g = self.ch.regs();
-        let num = self.ch.number();
-        let waker = self.ch.waker();
+    ///
+    /// It is possible to call this function and await the returned future later.
+    /// If an even occurs in the mean time, the future will immediately report ready.
+    pub fn wait(&mut self) -> impl Future<Output = ()> {
+        // NOTE: This is `-> impl Future` and not an `async fn` on purpose.
+        // Otherwise, events will only be detected starting at the first poll of the returned future.
+        Self::wait_internal(&mut self.ch)
+    }
+
+    /// Asynchronously wait for the pin to become high.
+    ///
+    /// The channel must be configured with [`InputChannelPolarity::LoToHi`] or [`InputChannelPolarity::Toggle`].
+    /// If the channel is not configured to detect rising edges, it is unspecified when the returned future completes.
+    ///
+    /// It is possible to call this function and await the returned future later.
+    /// If an even occurs in the mean time, the future will immediately report ready.
+    pub fn wait_for_high(&mut self) -> impl Future<Output = ()> {
+        // NOTE: This is `-> impl Future` and not an `async fn` on purpose.
+        // Otherwise, events will only be detected starting at the first poll of the returned future.
+
+        // Subscribe to the event before checking the pin level.
+        let wait = Self::wait_internal(&mut self.ch);
+        let pin = &self.pin;
+        async move {
+            if pin.is_high() {
+                return;
+            }
+            wait.await;
+        }
+    }
+
+    /// Asynchronously wait for the pin to become low.
+    ///
+    /// The channel must be configured with [`InputChannelPolarity::HiToLo`] or [`InputChannelPolarity::Toggle`].
+    /// If the channel is not configured to detect falling edges, it is unspecified when the returned future completes.
+    ///
+    /// It is possible to call this function and await the returned future later.
+    /// If an even occurs in the mean time, the future will immediately report ready.
+    pub fn wait_for_low(&mut self) -> impl Future<Output = ()> {
+        // NOTE: This is `-> impl Future` and not an `async fn` on purpose.
+        // Otherwise, events will only be detected starting at the first poll of the returned future.
+
+        // Subscribe to the event before checking the pin level.
+        let wait = Self::wait_internal(&mut self.ch);
+        let pin = &self.pin;
+        async move {
+            if pin.is_low() {
+                return;
+            }
+            wait.await;
+        }
+    }
+
+    /// Internal implementation for `wait()` and friends.
+    fn wait_internal(channel: &mut Peri<'_, AnyChannel>) -> impl Future<Output = ()> {
+        // NOTE: This is `-> impl Future` and not an `async fn` on purpose.
+        // Otherwise, events will only be detected starting at the first poll of the returned future.
+
+        let g = channel.regs();
+        let num = channel.number();
+        let waker = channel.waker();
 
         // Enable interrupt
         g.events_in(num).write_value(0);
         g.intenset(INTNUM).write(|w| w.0 = 1 << num);
 
-        poll_fn(|cx| {
+        poll_fn(move |cx| {
             CHANNEL_WAKERS[waker].register(cx.waker());
 
             if g.events_in(num).read() != 0 {
@@ -367,7 +424,6 @@ impl<'d> InputChannel<'d> {
                 Poll::Pending
             }
         })
-        .await;
     }
 
     /// Get the associated input pin.
diff --git a/examples/nrf52840/src/bin/gpiote_channel.rs b/examples/nrf52840/src/bin/gpiote_channel.rs
index c7ddc1d8d..e358779b2 100644
--- a/examples/nrf52840/src/bin/gpiote_channel.rs
+++ b/examples/nrf52840/src/bin/gpiote_channel.rs
@@ -12,10 +12,10 @@ async fn main(_spawner: Spawner) {
     let p = embassy_nrf::init(Default::default());
     info!("Starting!");
 
-    let ch1 = InputChannel::new(p.GPIOTE_CH0, p.P0_11, Pull::Up, InputChannelPolarity::HiToLo);
-    let ch2 = InputChannel::new(p.GPIOTE_CH1, p.P0_12, Pull::Up, InputChannelPolarity::LoToHi);
-    let ch3 = InputChannel::new(p.GPIOTE_CH2, p.P0_24, Pull::Up, InputChannelPolarity::Toggle);
-    let ch4 = InputChannel::new(p.GPIOTE_CH3, p.P0_25, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch1 = InputChannel::new(p.GPIOTE_CH0, p.P0_11, Pull::Up, InputChannelPolarity::HiToLo);
+    let mut ch2 = InputChannel::new(p.GPIOTE_CH1, p.P0_12, Pull::Up, InputChannelPolarity::LoToHi);
+    let mut ch3 = InputChannel::new(p.GPIOTE_CH2, p.P0_24, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch4 = InputChannel::new(p.GPIOTE_CH3, p.P0_25, Pull::Up, InputChannelPolarity::Toggle);
 
     let button1 = async {
         loop {
diff --git a/examples/nrf5340/src/bin/gpiote_channel.rs b/examples/nrf5340/src/bin/gpiote_channel.rs
index a085310ce..41ee732c3 100644
--- a/examples/nrf5340/src/bin/gpiote_channel.rs
+++ b/examples/nrf5340/src/bin/gpiote_channel.rs
@@ -12,10 +12,10 @@ async fn main(_spawner: Spawner) {
     let p = embassy_nrf::init(Default::default());
     info!("Starting!");
 
-    let ch1 = InputChannel::new(p.GPIOTE_CH0, p.P0_23, Pull::Up, InputChannelPolarity::HiToLo);
-    let ch2 = InputChannel::new(p.GPIOTE_CH1, p.P0_24, Pull::Up, InputChannelPolarity::LoToHi);
-    let ch3 = InputChannel::new(p.GPIOTE_CH2, p.P0_08, Pull::Up, InputChannelPolarity::Toggle);
-    let ch4 = InputChannel::new(p.GPIOTE_CH3, p.P0_09, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch1 = InputChannel::new(p.GPIOTE_CH0, p.P0_23, Pull::Up, InputChannelPolarity::HiToLo);
+    let mut ch2 = InputChannel::new(p.GPIOTE_CH1, p.P0_24, Pull::Up, InputChannelPolarity::LoToHi);
+    let mut ch3 = InputChannel::new(p.GPIOTE_CH2, p.P0_08, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch4 = InputChannel::new(p.GPIOTE_CH3, p.P0_09, Pull::Up, InputChannelPolarity::Toggle);
 
     let button1 = async {
         loop {
diff --git a/examples/nrf54l15/src/bin/gpiote_channel.rs b/examples/nrf54l15/src/bin/gpiote_channel.rs
index 6333250ba..cac8823f8 100644
--- a/examples/nrf54l15/src/bin/gpiote_channel.rs
+++ b/examples/nrf54l15/src/bin/gpiote_channel.rs
@@ -12,10 +12,10 @@ async fn main(_spawner: Spawner) {
     let p = embassy_nrf::init(Default::default());
     info!("Starting!");
 
-    let ch1 = InputChannel::new(p.GPIOTE20_CH0, p.P1_13, Pull::Up, InputChannelPolarity::HiToLo);
-    let ch2 = InputChannel::new(p.GPIOTE20_CH1, p.P1_09, Pull::Up, InputChannelPolarity::LoToHi);
-    let ch3 = InputChannel::new(p.GPIOTE20_CH2, p.P1_08, Pull::Up, InputChannelPolarity::Toggle);
-    let ch4 = InputChannel::new(p.GPIOTE30_CH0, p.P0_04, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch1 = InputChannel::new(p.GPIOTE20_CH0, p.P1_13, Pull::Up, InputChannelPolarity::HiToLo);
+    let mut ch2 = InputChannel::new(p.GPIOTE20_CH1, p.P1_09, Pull::Up, InputChannelPolarity::LoToHi);
+    let mut ch3 = InputChannel::new(p.GPIOTE20_CH2, p.P1_08, Pull::Up, InputChannelPolarity::Toggle);
+    let mut ch4 = InputChannel::new(p.GPIOTE30_CH0, p.P0_04, Pull::Up, InputChannelPolarity::Toggle);
 
     let button1 = async {
         loop {