Add per-core EXTI support

* Generate a core index put into the PAC for the peripherals to use as
  index into registers.
* Add EXTI v2 which uses CORE_INDEX to index exti registers

3 files changed, 230 insertions, 5 deletions

diff --git a/embassy-stm32/src/exti/v2.rs b/embassy-stm32/src/exti/v2.rs
index 8b1378917..2e62331fe 100644
--- a/embassy-stm32/src/exti/v2.rs
+++ b/embassy-stm32/src/exti/v2.rs
@@ -1 +1,184 @@
+use core::convert::Infallible;
+use core::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use embassy::traits::gpio::{WaitForAnyEdge, WaitForFallingEdge, WaitForRisingEdge};
+use embassy::util::{AtomicWaker, Unborrow};
+use embedded_hal::digital::v2::InputPin;
+use pac::exti::{regs, vals};
 
+use crate::gpio::{AnyPin, Input, Pin as GpioPin};
+use crate::pac;
+use crate::pac::CORE_INDEX;
+use crate::pac::{EXTI, SYSCFG};
+
+const EXTI_COUNT: usize = 16;
+const NEW_AW: AtomicWaker = AtomicWaker::new();
+static EXTI_WAKERS: [AtomicWaker; EXTI_COUNT] = [NEW_AW; EXTI_COUNT];
+
+pub unsafe fn on_irq() {
+    let bits = EXTI.pr(0).read().0;
+
+    // Mask all the channels that fired.
+    EXTI.cpu(CORE_INDEX)
+        .imr(CORE_INDEX)
+        .modify(|w| w.0 &= !bits);
+
+    // Wake the tasks
+    for pin in BitIter(bits) {
+        EXTI_WAKERS[pin as usize].wake();
+    }
+
+    // Clear pending
+    EXTI.pr(0).write_value(regs::Pr(bits));
+}
+
+struct BitIter(u32);
+
+impl Iterator for BitIter {
+    type Item = u32;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.0.trailing_zeros() {
+            32 => None,
+            b => {
+                self.0 &= !(1 << b);
+                Some(b)
+            }
+        }
+    }
+}
+
+/// EXTI input driver
+pub struct ExtiInput<'d, T: GpioPin> {
+    pin: Input<'d, T>,
+}
+
+impl<'d, T: GpioPin> Unpin for ExtiInput<'d, T> {}
+
+impl<'d, T: GpioPin> ExtiInput<'d, T> {
+    pub fn new(pin: Input<'d, T>, _ch: impl Unborrow<Target = T::ExtiChannel> + 'd) -> Self {
+        Self { pin }
+    }
+}
+
+impl<'d, T: GpioPin> InputPin for ExtiInput<'d, T> {
+    type Error = Infallible;
+
+    fn is_high(&self) -> Result<bool, Self::Error> {
+        self.pin.is_high()
+    }
+
+    fn is_low(&self) -> Result<bool, Self::Error> {
+        self.pin.is_low()
+    }
+}
+
+impl<'d, T: GpioPin> WaitForRisingEdge for ExtiInput<'d, T> {
+    type Future<'a> = ExtiInputFuture<'a>;
+
+    fn wait_for_rising_edge<'a>(&'a mut self) -> Self::Future<'a> {
+        ExtiInputFuture::new(
+            self.pin.pin.pin(),
+            self.pin.pin.port(),
+            vals::Rt::ENABLED,
+            vals::Ft::DISABLED,
+        )
+    }
+}
+
+impl<'d, T: GpioPin> WaitForFallingEdge for ExtiInput<'d, T> {
+    type Future<'a> = ExtiInputFuture<'a>;
+
+    fn wait_for_falling_edge<'a>(&'a mut self) -> Self::Future<'a> {
+        ExtiInputFuture::new(
+            self.pin.pin.pin(),
+            self.pin.pin.port(),
+            vals::Rt::DISABLED,
+            vals::Ft::ENABLED,
+        )
+    }
+}
+
+impl<'d, T: GpioPin> WaitForAnyEdge for ExtiInput<'d, T> {
+    type Future<'a> = ExtiInputFuture<'a>;
+
+    fn wait_for_any_edge<'a>(&'a mut self) -> Self::Future<'a> {
+        ExtiInputFuture::new(
+            self.pin.pin.pin(),
+            self.pin.pin.port(),
+            vals::Rt::ENABLED,
+            vals::Ft::ENABLED,
+        )
+    }
+}
+
+pub struct ExtiInputFuture<'a> {
+    pin: u8,
+    phantom: PhantomData<&'a mut AnyPin>,
+}
+
+impl<'a> ExtiInputFuture<'a> {
+    fn new(pin: u8, port: u8, rising: vals::Rt, falling: vals::Ft) -> Self {
+        cortex_m::interrupt::free(|_| unsafe {
+            let pin = pin as usize;
+            SYSCFG.exticr(pin / 4).modify(|w| w.set_exti(pin % 4, port));
+            EXTI.rtsr(CORE_INDEX).modify(|w| w.set_rt(pin, rising));
+            EXTI.ftsr(CORE_INDEX).modify(|w| w.set_ft(pin, falling));
+            EXTI.pr(CORE_INDEX).write(|w| w.set_pif(pin, true)); // clear pending bit
+            EXTI.cpu(CORE_INDEX)
+                .imr(CORE_INDEX)
+                .modify(|w| w.set_im(pin, vals::Mr::UNMASKED));
+        });
+
+        Self {
+            pin,
+            phantom: PhantomData,
+        }
+    }
+}
+
+impl<'a> Drop for ExtiInputFuture<'a> {
+    fn drop(&mut self) {
+        cortex_m::interrupt::free(|_| unsafe {
+            let pin = self.pin as _;
+            EXTI.cpu(CORE_INDEX)
+                .imr(CORE_INDEX)
+                .modify(|w| w.set_im(pin, vals::Mr::MASKED));
+        });
+    }
+}
+
+impl<'a> Future for ExtiInputFuture<'a> {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        EXTI_WAKERS[self.pin as usize].register(cx.waker());
+
+        if unsafe {
+            EXTI.cpu(CORE_INDEX)
+                .imr(CORE_INDEX)
+                .read()
+                .im(self.pin as _)
+                == vals::Mr::MASKED
+        } {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+}
+
+use crate::interrupt;
+
+macro_rules! impl_irq {
+    ($e:ident) => {
+        #[interrupt]
+        unsafe fn $e() {
+            on_irq()
+        }
+    };
+}
+
+foreach_exti_irq!(impl_irq);
diff --git a/examples/stm32wl55/src/bin/button_exti.rs b/examples/stm32wl55/src/bin/button_exti.rs
new file mode 100644
index 000000000..2f6e55115
--- /dev/null
+++ b/examples/stm32wl55/src/bin/button_exti.rs
@@ -0,0 +1,34 @@
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use embassy::executor::Spawner;
+use embassy_stm32::dbgmcu::Dbgmcu;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::gpio::{Input, Pull};
+use embassy_stm32::Peripherals;
+use embassy_traits::gpio::{WaitForFallingEdge, WaitForRisingEdge};
+use example_common::*;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    info!("Hello World!");
+
+    unsafe { Dbgmcu::enable_all() };
+
+    let button = Input::new(p.PA0, Pull::Up);
+    let mut button = ExtiInput::new(button, p.EXTI0);
+
+    info!("Press the USER button...");
+
+    loop {
+        button.wait_for_falling_edge().await;
+        info!("Pressed!");
+        button.wait_for_rising_edge().await;
+        info!("Released!");
+    }
+}
diff --git a/stm32-metapac-gen/src/lib.rs b/stm32-metapac-gen/src/lib.rs
index ae401bb67..b1980d84e 100644
--- a/stm32-metapac-gen/src/lib.rs
+++ b/stm32-metapac-gen/src/lib.rs
@@ -231,21 +231,23 @@ pub fn gen(options: Options) {
         let chip: Chip = serde_yaml::from_slice(&chip).unwrap();
 
         println!("looking for core {:?}", core_name);
-        let core: Option<&Core> = if let Some(core_name) = core_name {
+        let core: Option<(&Core, usize)> = if let Some(core_name) = core_name {
             let core_name = core_name.to_ascii_lowercase();
             let mut c = None;
-            for core in chip.cores.iter() {
+            let mut idx = 0;
+            for (i, core) in chip.cores.iter().enumerate() {
                 if core.name == core_name {
                     c = Some(core);
+                    idx = i;
                     break;
                 }
             }
-            c
+            c.map(|c| (c, idx))
         } else {
-            Some(&chip.cores[0])
+            Some((&chip.cores[0], 0))
         };
 
-        let core = core.unwrap();
+        let (core, core_index) = core.unwrap();
         let core_name = &core.name;
 
         let mut ir = ir::IR::new();
@@ -584,6 +586,12 @@ pub fn gen(options: Options) {
             )
             .unwrap();
         }
+        write!(
+            &mut extra,
+            "pub const CORE_INDEX: usize = {};\n",
+            core_index
+        )
+        .unwrap();
 
         // Cleanups!
         transform::sort::Sort {}.run(&mut ir).unwrap();