Merge #694

694: RTIC 2 r=AfoHT a=korken89



Co-authored-by: Emil Fresk <emil.fresk@gmail.com>
Co-authored-by: Per Lindgren <per.lindgren@ltu.se>

1 files changed, 163 insertions, 0 deletions

diff --git a/rtic-monotonics/src/systick.rs b/rtic-monotonics/src/systick.rs
new file mode 100644
index 0000000..691d7c7
--- /dev/null
+++ b/rtic-monotonics/src/systick.rs
@@ -0,0 +1,163 @@
+//! ...
+
+use super::Monotonic;
+pub use super::{TimeoutError, TimerQueue};
+use atomic_polyfill::{AtomicU32, Ordering};
+use core::future::Future;
+use cortex_m::peripheral::SYST;
+pub use fugit::ExtU32;
+
+// Features should be additive, here systick-100hz gets picked if both
+// `systick-100hz` and `systick-10khz` are enabled.
+
+cfg_if::cfg_if! {
+    if #[cfg(feature = "systick-100hz")]
+    {
+        const TIMER_HZ: u32 = 100;
+    } else if #[cfg(feature = "systick-10khz")]
+    {
+        const TIMER_HZ: u32 = 10_000;
+    } else {
+        // Default case is 1 kHz
+        const TIMER_HZ: u32 = 1_000;
+    }
+}
+
+/// Systick implementing `rtic_monotonic::Monotonic` which runs at 1 kHz, 100Hz or 10 kHz.
+pub struct Systick;
+
+impl Systick {
+    /// Start a `Monotonic` based on SysTick.
+    ///
+    /// The `sysclk` parameter is the speed at which SysTick runs at. This value should come from
+    /// the clock generation function of the used HAL.
+    ///
+    /// Notice that the actual rate of the timer is a best approximation based on the given
+    /// `sysclk` and `TIMER_HZ`.
+    ///
+    /// Note: Give the return value to `TimerQueue::initialize()` to initialize the timer queue.
+    pub fn start(mut systick: cortex_m::peripheral::SYST, sysclk: u32) {
+        // + TIMER_HZ / 2 provides round to nearest instead of round to 0.
+        // - 1 as the counter range is inclusive [0, reload]
+        let reload = (sysclk + TIMER_HZ / 2) / TIMER_HZ - 1;
+
+        assert!(reload <= 0x00ff_ffff);
+        assert!(reload > 0);
+
+        systick.disable_counter();
+        systick.set_clock_source(cortex_m::peripheral::syst::SystClkSource::Core);
+        systick.set_reload(reload);
+        systick.enable_interrupt();
+        systick.enable_counter();
+
+        SYSTICK_TIMER_QUEUE.initialize(Systick {});
+    }
+
+    fn systick() -> SYST {
+        unsafe { core::mem::transmute::<(), SYST>(()) }
+    }
+}
+
+static SYSTICK_CNT: AtomicU32 = AtomicU32::new(0);
+static SYSTICK_TIMER_QUEUE: TimerQueue<Systick> = TimerQueue::new();
+
+// Forward timerqueue interface
+impl Systick {
+    /// Used to access the underlying timer queue
+    #[doc(hidden)]
+    pub fn __tq() -> &'static TimerQueue<Systick> {
+        &SYSTICK_TIMER_QUEUE
+    }
+
+    /// Timeout at a specific time.
+    pub async fn timeout_at<F: Future>(
+        instant: <Self as Monotonic>::Instant,
+        future: F,
+    ) -> Result<F::Output, TimeoutError> {
+        SYSTICK_TIMER_QUEUE.timeout_at(instant, future).await
+    }
+
+    /// Timeout after a specific duration.
+    #[inline]
+    pub async fn timeout_after<F: Future>(
+        duration: <Self as Monotonic>::Duration,
+        future: F,
+    ) -> Result<F::Output, TimeoutError> {
+        SYSTICK_TIMER_QUEUE.timeout_after(duration, future).await
+    }
+
+    /// Delay for some duration of time.
+    #[inline]
+    pub async fn delay(duration: <Self as Monotonic>::Duration) {
+        SYSTICK_TIMER_QUEUE.delay(duration).await;
+    }
+
+    /// Delay to some specific time instant.
+    pub async fn delay_until(instant: <Self as Monotonic>::Instant) {
+        SYSTICK_TIMER_QUEUE.delay_until(instant).await;
+    }
+}
+
+impl Monotonic for Systick {
+    type Instant = fugit::TimerInstantU32<TIMER_HZ>;
+    type Duration = fugit::TimerDurationU32<TIMER_HZ>;
+
+    const ZERO: Self::Instant = Self::Instant::from_ticks(0);
+
+    fn now() -> Self::Instant {
+        if Self::systick().has_wrapped() {
+            SYSTICK_CNT.fetch_add(1, Ordering::AcqRel);
+        }
+
+        Self::Instant::from_ticks(SYSTICK_CNT.load(Ordering::Relaxed))
+    }
+
+    fn set_compare(_: Self::Instant) {
+        // No need to do something here, we get interrupts anyway.
+    }
+
+    fn clear_compare_flag() {
+        // NOOP with SysTick interrupt
+    }
+
+    fn pend_interrupt() {
+        cortex_m::peripheral::SCB::set_pendst();
+    }
+
+    fn on_interrupt() {
+        if Self::systick().has_wrapped() {
+            SYSTICK_CNT.fetch_add(1, Ordering::AcqRel);
+        }
+    }
+
+    fn enable_timer() {}
+
+    fn disable_timer() {}
+}
+
+#[cfg(feature = "embedded-hal-async")]
+impl embedded_hal_async::delay::DelayUs for Systick {
+    type Error = core::convert::Infallible;
+
+    async fn delay_us(&mut self, us: u32) -> Result<(), Self::Error> {
+        SYSTICK_TIMER_QUEUE.delay(us.micros()).await;
+        Ok(())
+    }
+
+    async fn delay_ms(&mut self, ms: u32) -> Result<(), Self::Error> {
+        SYSTICK_TIMER_QUEUE.delay(ms.millis()).await;
+        Ok(())
+    }
+}
+
+/// Register the Systick interrupt for the monotonic.
+#[macro_export]
+macro_rules! make_systick_handler {
+    () => {
+        #[no_mangle]
+        #[allow(non_snake_case)]
+        unsafe extern "C" fn SysTick() {
+            rtic_monotonics::systick::Systick::__tq().on_monotonic_interrupt();
+        }
+    };
+}