Make interrupt module more standard.

- Move typelevel interrupts to a special-purpose mod: `embassy_xx::interrupt::typelevel`.
- Reexport the PAC interrupt enum in `embassy_xx::interrupt`.

This has a few advantages:
- The `embassy_xx::interrupt` module is now more "standard".
  - It works with `cortex-m` functions for manipulating interrupts, for example.
  - It works with RTIC.
- the interrupt enum allows holding value that can be "any interrupt at runtime", this can't be done with typelevel irqs.
- When "const-generics on enums" is stable, we can remove the typelevel interrupts without disruptive changes to `embassy_xx::interrupt`.

embassy-stm32/src/usart/buffered.rs

@@ -2,18 +2,18 @@ use core::future::poll_fn;
 use core::slice;
 use core::task::Poll;
 
-use embassy_cortex_m::interrupt::Interrupt;
 use embassy_hal_common::atomic_ring_buffer::RingBuffer;
 use embassy_sync::waitqueue::AtomicWaker;
 
 use super::*;
+use crate::interrupt::typelevel::Interrupt;
 
 /// Interrupt handler.
 pub struct InterruptHandler<T: BasicInstance> {
     _phantom: PhantomData<T>,
 }
 
-impl<T: BasicInstance> interrupt::Handler<T::Interrupt> for InterruptHandler<T> {
+impl<T: BasicInstance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandler<T> {
     unsafe fn on_interrupt() {
         let r = T::regs();
         let state = T::buffered_state();
@@ -115,7 +115,7 @@ pub struct BufferedUartRx<'d, T: BasicInstance> {
 impl<'d, T: BasicInstance> BufferedUart<'d, T> {
     pub fn new(
         peri: impl Peripheral<P = T> + 'd,
-        _irq: impl interrupt::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
         rx: impl Peripheral<P = impl RxPin<T>> + 'd,
         tx: impl Peripheral<P = impl TxPin<T>> + 'd,
         tx_buffer: &'d mut [u8],
@@ -130,7 +130,7 @@ impl<'d, T: BasicInstance> BufferedUart<'d, T> {
 
     pub fn new_with_rtscts(
         peri: impl Peripheral<P = T> + 'd,
-        _irq: impl interrupt::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
         rx: impl Peripheral<P = impl RxPin<T>> + 'd,
         tx: impl Peripheral<P = impl TxPin<T>> + 'd,
         rts: impl Peripheral<P = impl RtsPin<T>> + 'd,
@@ -159,7 +159,7 @@ impl<'d, T: BasicInstance> BufferedUart<'d, T> {
     #[cfg(not(any(usart_v1, usart_v2)))]
     pub fn new_with_de(
         peri: impl Peripheral<P = T> + 'd,
-        _irq: impl interrupt::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
         rx: impl Peripheral<P = impl RxPin<T>> + 'd,
         tx: impl Peripheral<P = impl TxPin<T>> + 'd,
         de: impl Peripheral<P = impl DePin<T>> + 'd,