This provides a helper function with an async implementation, that
will only return (or error) when it was able to read that many bytes,
sleeping until ready.
Additionally, corrected the documentation for Ringbuffer functions to use
"elements" instead of "bytes" as the types were already generic over the
word/element size.
- 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`.
- Move Interrupt and InterruptExecutor from `embassy` to `embassy-cortex-m`.
- Move Unborrow from `embassy` to `embassy-hal-common` (nothing in `embassy` requires it anymore)
- Move PeripheralMutex from `embassy-hal-common` to `embassy-cortex-m`.
Previously, every dma interrupt handler called the same `on_irq`
function which had to check the state of every dma channel.
Now, each dma interrupt handler only calls an `on_irq` method for its
corresponding channel or channels.
These files end up containing chip-specific info, so they deduplicate
really badly when building docs for all 1200 chips.
The doc generator removes files starting with `_`.
