Merge #1404

1404: feat(stm32): Add DMA based, ring-buffer based rx uart, v3 r=Dirbaio a=rmja

This PR replaces #1150. Comparing to that PR, this one has the following changes:

* The implementation now aligns with the new stm32 dma module, thanks `@Dirbaio!`
* Calls to `read()` now returns on either 1) idle line, or 2) ring buffer is at most half full. This is different from the previous pr, which would return a lot of 1 byte reads. Thank you `@chemicstry` for making me realize that it was actually not what I wanted. This is accomplished using half-transfer completed and full-transfer completed interrupts. Both seems to be supported on both dma and bdma.

The implementation still have the issue mentioned here: https://github.com/embassy-rs/embassy/pull/1150#discussion_r1094627035

Regarding the todos here: https://github.com/embassy-rs/embassy/pull/1150#issuecomment-1513905925. I have removed the exposure of ndtr from `dma::RingBuffer` to the uart so that the uart now simply calls `ringbuf::reload_position()` to align the position within the ring buffer to that of the actual running dma controller. BDMA and GPDMA is not implemented. I do not have any chips with those dma controllers, so maybe someone else should to this so that it can be tested.

The `saturate_serial` test utility inside `tests/utils` has an `--idles` switch which can be used to saturate the uart from a pc, but with random idles.

Because embassy-stm32 now can have tests, we should probably run them in ci. I do this locally to test the DmaRingBuffer:  `cargo test --no-default-features --features stm32f429ig`.

cc `@chemicstry` `@Dirbaio` 


Co-authored-by: Rasmus Melchior Jacobsen <[email protected]>
Co-authored-by: Dario Nieuwenhuis <[email protected]>

1 files changed, 0 insertions, 11 deletions

diff --git a/tests/stm32/src/example_common.rs b/tests/stm32/src/example_common.rs
index c47ed75c4..a4f8668c7 100644
--- a/tests/stm32/src/example_common.rs
+++ b/tests/stm32/src/example_common.rs
@@ -1,22 +1,11 @@
 #![macro_use]
 
-use core::sync::atomic::{AtomicUsize, Ordering};
-
 pub use defmt::*;
 #[allow(unused)]
 use embassy_stm32::time::Hertz;
 use embassy_stm32::Config;
 use {defmt_rtt as _, panic_probe as _};
 
-defmt::timestamp! {"{=u64}", {
-        static COUNT: AtomicUsize = AtomicUsize::new(0);
-        // NOTE(no-CAS) `timestamps` runs with interrupts disabled
-        let n = COUNT.load(Ordering::Relaxed);
-        COUNT.store(n + 1, Ordering::Relaxed);
-        n as u64
-    }
-}
-
 pub fn config() -> Config {
     #[allow(unused_mut)]
     let mut config = Config::default();