stm32/timer: Support one pulse mode

Currently does not support output pins so it really is only useful to
create delayed interrupts based on external signals.

3 files changed, 415 insertions, 0 deletions

diff --git a/embassy-stm32/src/timer/low_level.rs b/embassy-stm32/src/timer/low_level.rs
index 5b0c95109..524c64c14 100644
--- a/embassy-stm32/src/timer/low_level.rs
+++ b/embassy-stm32/src/timer/low_level.rs
@@ -425,6 +425,36 @@ impl<'d, T: GeneralInstance1Channel> Timer<'d, T> {
             TimerBits::Bits32 => self.regs_gp32_unchecked().arr().read(),
         }
     }
+
+    /// Set the max compare value.
+    ///
+    /// An update event is generated to load the new value. The update event is
+    /// generated such that it will not cause an interrupt or DMA request.
+    pub fn set_max_compare_value(&self, ticks: u32) {
+        match T::BITS {
+            TimerBits::Bits16 => {
+                let arr = unwrap!(u16::try_from(ticks));
+
+                let regs = self.regs_1ch();
+                regs.arr().write(|r| r.set_arr(arr));
+
+                regs.cr1().modify(|r| r.set_urs(vals::Urs::COUNTER_ONLY));
+                regs.egr().write(|r| r.set_ug(true));
+                regs.cr1().modify(|r| r.set_urs(vals::Urs::ANY_EVENT));
+            }
+            #[cfg(not(stm32l0))]
+            TimerBits::Bits32 => {
+                let arr = ticks;
+
+                let regs = self.regs_gp32_unchecked();
+                regs.arr().write_value(arr);
+
+                regs.cr1().modify(|r| r.set_urs(vals::Urs::COUNTER_ONLY));
+                regs.egr().write(|r| r.set_ug(true));
+                regs.cr1().modify(|r| r.set_urs(vals::Urs::ANY_EVENT));
+            }
+        }
+    }
 }
 
 impl<'d, T: GeneralInstance2Channel> Timer<'d, T> {
diff --git a/embassy-stm32/src/timer/mod.rs b/embassy-stm32/src/timer/mod.rs
index 645556e8c..4a5aa5e00 100644
--- a/embassy-stm32/src/timer/mod.rs
+++ b/embassy-stm32/src/timer/mod.rs
@@ -9,6 +9,7 @@ use embassy_sync::waitqueue::AtomicWaker;
 pub mod complementary_pwm;
 pub mod input_capture;
 pub mod low_level;
+pub mod one_pulse;
 pub mod pwm_input;
 pub mod qei;
 pub mod simple_pwm;
diff --git a/embassy-stm32/src/timer/one_pulse.rs b/embassy-stm32/src/timer/one_pulse.rs
new file mode 100644
index 000000000..43ba3dedf
--- /dev/null
+++ b/embassy-stm32/src/timer/one_pulse.rs
@@ -0,0 +1,384 @@
+//! One pulse mode driver.
+
+use core::future::Future;
+use core::marker::PhantomData;
+use core::mem::ManuallyDrop;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+use super::low_level::{
+    CountingMode, FilterValue, InputCaptureMode, InputTISelection, SlaveMode, Timer, TriggerSource,
+};
+use super::{
+    CaptureCompareInterruptHandler, Channel, Channel1Pin, Channel2Pin, ExternalTriggerPin, GeneralInstance4Channel,
+};
+pub use super::{Ch1, Ch2};
+use crate::gpio::{AfType, AnyPin, Pull};
+use crate::interrupt::typelevel::{Binding, Interrupt};
+use crate::pac::timer::vals::Etp;
+use crate::time::Hertz;
+use crate::{into_ref, Peripheral, PeripheralRef};
+
+/// External input marker type.
+pub enum Ext {}
+
+/// External trigger pin trigger polarity.
+#[derive(Clone, Copy)]
+pub enum ExternalTriggerPolarity {
+    /// Rising edge only.
+    Rising,
+    /// Falling edge only.
+    Falling,
+}
+
+impl From<ExternalTriggerPolarity> for Etp {
+    fn from(mode: ExternalTriggerPolarity) -> Self {
+        match mode {
+            ExternalTriggerPolarity::Rising => 0.into(),
+            ExternalTriggerPolarity::Falling => 1.into(),
+        }
+    }
+}
+
+/// Trigger pin wrapper.
+///
+/// This wraps a pin to make it usable as a timer trigger.
+pub struct TriggerPin<'d, T, C> {
+    _pin: PeripheralRef<'d, AnyPin>,
+    phantom: PhantomData<(T, C)>,
+}
+
+macro_rules! channel_impl {
+    ($new_chx:ident, $channel:ident, $pin_trait:ident) => {
+        impl<'d, T: GeneralInstance4Channel> TriggerPin<'d, T, $channel> {
+            #[doc = concat!("Create a new ", stringify!($channel), " trigger pin instance.")]
+            pub fn $new_chx(pin: impl Peripheral<P = impl $pin_trait<T>> + 'd, pull: Pull) -> Self {
+                into_ref!(pin);
+                pin.set_as_af(pin.af_num(), AfType::input(pull));
+                TriggerPin {
+                    _pin: pin.map_into(),
+                    phantom: PhantomData,
+                }
+            }
+        }
+    };
+}
+
+channel_impl!(new_ch1, Ch1, Channel1Pin);
+channel_impl!(new_ch2, Ch2, Channel2Pin);
+channel_impl!(new_ext, Ext, ExternalTriggerPin);
+
+/// One pulse driver.
+///
+/// Generates a pulse after a trigger and some configurable delay.
+pub struct OnePulse<'d, T: GeneralInstance4Channel> {
+    inner: Timer<'d, T>,
+}
+
+impl<'d, T: GeneralInstance4Channel> OnePulse<'d, T> {
+    /// Create a new one pulse driver.
+    ///
+    /// The pulse is triggered by a channel 1 input pin on both rising and
+    /// falling edges. Channel 1 will unusable as an output.
+    pub fn new_ch1_edge_detect(
+        tim: impl Peripheral<P = T> + 'd,
+        _pin: TriggerPin<'d, T, Ch1>,
+        _irq: impl Binding<T::CaptureCompareInterrupt, CaptureCompareInterruptHandler<T>> + 'd,
+        freq: Hertz,
+        pulse_end: u32,
+        counting_mode: CountingMode,
+    ) -> Self {
+        let mut this = Self { inner: Timer::new(tim) };
+
+        this.inner.set_trigger_source(TriggerSource::TI1F_ED);
+        this.inner
+            .set_input_ti_selection(Channel::Ch1, InputTISelection::Normal);
+        this.inner
+            .set_input_capture_filter(Channel::Ch1, FilterValue::NO_FILTER);
+        this.new_inner(freq, pulse_end, counting_mode);
+
+        this
+    }
+
+    /// Create a new one pulse driver.
+    ///
+    /// The pulse is triggered by a channel 1 input pin. Channel 1 will unusable
+    /// as an output.
+    pub fn new_ch1(
+        tim: impl Peripheral<P = T> + 'd,
+        _pin: TriggerPin<'d, T, Ch1>,
+        _irq: impl Binding<T::CaptureCompareInterrupt, CaptureCompareInterruptHandler<T>> + 'd,
+        freq: Hertz,
+        pulse_end: u32,
+        counting_mode: CountingMode,
+        capture_mode: InputCaptureMode,
+    ) -> Self {
+        let mut this = Self { inner: Timer::new(tim) };
+
+        this.inner.set_trigger_source(TriggerSource::TI1FP1);
+        this.inner
+            .set_input_ti_selection(Channel::Ch1, InputTISelection::Normal);
+        this.inner
+            .set_input_capture_filter(Channel::Ch1, FilterValue::NO_FILTER);
+        this.inner.set_input_capture_mode(Channel::Ch1, capture_mode);
+        this.new_inner(freq, pulse_end, counting_mode);
+
+        this
+    }
+
+    /// Create a new one pulse driver.
+    ///
+    /// The pulse is triggered by a channel 2 input pin. Channel 2 will unusable
+    /// as an output.
+    pub fn new_ch2(
+        tim: impl Peripheral<P = T> + 'd,
+        _pin: TriggerPin<'d, T, Ch1>,
+        _irq: impl Binding<T::CaptureCompareInterrupt, CaptureCompareInterruptHandler<T>> + 'd,
+        freq: Hertz,
+        pulse_end: u32,
+        counting_mode: CountingMode,
+        capture_mode: InputCaptureMode,
+    ) -> Self {
+        let mut this = Self { inner: Timer::new(tim) };
+
+        this.inner.set_trigger_source(TriggerSource::TI2FP2);
+        this.inner
+            .set_input_ti_selection(Channel::Ch2, InputTISelection::Normal);
+        this.inner
+            .set_input_capture_filter(Channel::Ch2, FilterValue::NO_FILTER);
+        this.inner.set_input_capture_mode(Channel::Ch2, capture_mode);
+        this.new_inner(freq, pulse_end, counting_mode);
+
+        this
+    }
+
+    /// Create a new one pulse driver.
+    ///
+    /// The pulse is triggered by a external trigger input pin.
+    pub fn new_ext(
+        tim: impl Peripheral<P = T> + 'd,
+        _pin: TriggerPin<'d, T, Ext>,
+        _irq: impl Binding<T::CaptureCompareInterrupt, CaptureCompareInterruptHandler<T>> + 'd,
+        freq: Hertz,
+        pulse_end: u32,
+        counting_mode: CountingMode,
+        polarity: ExternalTriggerPolarity,
+    ) -> Self {
+        let mut this = Self { inner: Timer::new(tim) };
+
+        this.inner.regs_gp16().smcr().modify(|r| {
+            r.set_etp(polarity.into());
+            // No pre-scaling
+            r.set_etps(0.into());
+            // No filtering
+            r.set_etf(FilterValue::NO_FILTER);
+        });
+        this.inner.set_trigger_source(TriggerSource::ETRF);
+        this.new_inner(freq, pulse_end, counting_mode);
+
+        this
+    }
+
+    fn new_inner(&mut self, freq: Hertz, pulse_end: u32, counting_mode: CountingMode) {
+        self.inner.set_counting_mode(counting_mode);
+        self.inner.set_tick_freq(freq);
+        self.inner.set_max_compare_value(pulse_end);
+        self.inner.regs_core().cr1().modify(|r| r.set_opm(true));
+        // Required for advanced timers, see GeneralInstance4Channel for details
+        self.inner.enable_outputs();
+        self.inner.set_slave_mode(SlaveMode::TRIGGER_MODE);
+
+        T::CaptureCompareInterrupt::unpend();
+        unsafe { T::CaptureCompareInterrupt::enable() };
+    }
+
+    /// Get the end of the pulse in ticks from the trigger.
+    pub fn pulse_end(&self) -> u32 {
+        let max = self.inner.get_max_compare_value();
+        assert!(max < u32::MAX);
+        max + 1
+    }
+
+    /// Set the end of the pulse in ticks from the trigger.
+    pub fn set_pulse_end(&mut self, ticks: u32) {
+        self.inner.set_max_compare_value(ticks)
+    }
+
+    /// Reset the timer on each trigger
+    #[cfg(not(stm32l0))]
+    pub fn set_reset_on_trigger(&mut self, reset: bool) {
+        let slave_mode = if reset {
+            SlaveMode::COMBINED_RESET_TRIGGER
+        } else {
+            SlaveMode::TRIGGER_MODE
+        };
+        self.inner.set_slave_mode(slave_mode);
+    }
+
+    /// Get a single channel
+    ///
+    /// If you need to use multiple channels, use [`Self::split`].
+    pub fn channel(&mut self, channel: Channel) -> OnePulseChannel<'_, T> {
+        OnePulseChannel {
+            inner: unsafe { self.inner.clone_unchecked() },
+            channel,
+        }
+    }
+
+    /// Channel 1
+    ///
+    /// This is just a convenience wrapper around [`Self::channel`].
+    ///
+    /// If you need to use multiple channels, use [`Self::split`].
+    pub fn ch1(&mut self) -> OnePulseChannel<'_, T> {
+        self.channel(Channel::Ch1)
+    }
+
+    /// Channel 2
+    ///
+    /// This is just a convenience wrapper around [`Self::channel`].
+    ///
+    /// If you need to use multiple channels, use [`Self::split`].
+    pub fn ch2(&mut self) -> OnePulseChannel<'_, T> {
+        self.channel(Channel::Ch2)
+    }
+
+    /// Channel 3
+    ///
+    /// This is just a convenience wrapper around [`Self::channel`].
+    ///
+    /// If you need to use multiple channels, use [`Self::split`].
+    pub fn ch3(&mut self) -> OnePulseChannel<'_, T> {
+        self.channel(Channel::Ch3)
+    }
+
+    /// Channel 4
+    ///
+    /// This is just a convenience wrapper around [`Self::channel`].
+    ///
+    /// If you need to use multiple channels, use [`Self::split`].
+    pub fn ch4(&mut self) -> OnePulseChannel<'_, T> {
+        self.channel(Channel::Ch4)
+    }
+
+    /// Splits a [`OnePulse`] into four output channels.
+    // TODO: I hate the name "split"
+    pub fn split(self) -> OnePulseChannels<'static, T>
+    where
+        // must be static because the timer will never be dropped/disabled
+        'd: 'static,
+    {
+        // without this, the timer would be disabled at the end of this function
+        let timer = ManuallyDrop::new(self.inner);
+
+        let ch = |channel| OnePulseChannel {
+            inner: unsafe { timer.clone_unchecked() },
+            channel,
+        };
+
+        OnePulseChannels {
+            ch1: ch(Channel::Ch1),
+            ch2: ch(Channel::Ch2),
+            ch3: ch(Channel::Ch3),
+            ch4: ch(Channel::Ch4),
+        }
+    }
+}
+
+/// A group of four [`OnePulseChannel`]s, obtained from [`OnePulse::split`].
+pub struct OnePulseChannels<'d, T: GeneralInstance4Channel> {
+    /// Channel 1
+    pub ch1: OnePulseChannel<'d, T>,
+    /// Channel 2
+    pub ch2: OnePulseChannel<'d, T>,
+    /// Channel 3
+    pub ch3: OnePulseChannel<'d, T>,
+    /// Channel 4
+    pub ch4: OnePulseChannel<'d, T>,
+}
+
+/// A single channel of a one pulse-configured timer, obtained from
+/// [`OnePulse::split`],[`OnePulse::channel`], [`OnePulse::ch1`], etc.
+///
+/// It is not possible to change the pulse end tick because the end tick
+/// configuration is shared with all four channels.
+pub struct OnePulseChannel<'d, T: GeneralInstance4Channel> {
+    inner: ManuallyDrop<Timer<'d, T>>,
+    channel: Channel,
+}
+
+impl<'d, T: GeneralInstance4Channel> OnePulseChannel<'d, T> {
+    /// Get the end of the pulse in ticks from the trigger.
+    pub fn pulse_end(&self) -> u32 {
+        let max = self.inner.get_max_compare_value();
+        assert!(max < u32::MAX);
+        max + 1
+    }
+
+    /// Get the width of the pulse in ticks.
+    pub fn pulse_width(&mut self) -> u32 {
+        self.pulse_end().saturating_sub(self.pulse_delay())
+    }
+
+    /// Get the start of the pulse in ticks from the trigger.
+    pub fn pulse_delay(&mut self) -> u32 {
+        self.inner.get_compare_value(self.channel)
+    }
+
+    /// Set the start of the pulse in ticks from the trigger.
+    pub fn set_pulse_delay(&mut self, delay: u32) {
+        assert!(delay <= self.pulse_end());
+        self.inner.set_compare_value(self.channel, delay);
+    }
+
+    /// Set the pulse width in ticks.
+    pub fn set_pulse_width(&mut self, width: u32) {
+        assert!(width <= self.pulse_end());
+        self.set_pulse_delay(self.pulse_end() - width);
+    }
+
+    /// Waits until the trigger and following delay has passed.
+    pub async fn wait_for_pulse_start(&mut self) {
+        self.inner.enable_input_interrupt(self.channel, true);
+
+        OnePulseFuture::<T> {
+            channel: self.channel,
+            phantom: PhantomData,
+        }
+        .await
+    }
+}
+
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+struct OnePulseFuture<T: GeneralInstance4Channel> {
+    channel: Channel,
+    phantom: PhantomData<T>,
+}
+
+impl<'d, T: GeneralInstance4Channel> Drop for OnePulseFuture<T> {
+    fn drop(&mut self) {
+        critical_section::with(|_| {
+            let regs = unsafe { crate::pac::timer::TimGp16::from_ptr(T::regs()) };
+
+            // disable interrupt enable
+            regs.dier().modify(|w| w.set_ccie(self.channel.index(), false));
+        });
+    }
+}
+
+impl<'d, T: GeneralInstance4Channel> Future for OnePulseFuture<T> {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        T::state().cc_waker[self.channel.index()].register(cx.waker());
+
+        let regs = unsafe { crate::pac::timer::TimGp16::from_ptr(T::regs()) };
+
+        let dier = regs.dier().read();
+        if !dier.ccie(self.channel.index()) {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+}