UART DMA improvements and refactoring

CHANGELOG.md

@@ -67,7 +67,25 @@
 
 ### Changed
 
 - The MSRV was bumped to 1.59 ([#340])
+### Changed
+
+- serial: The DMA functions `write_all` and `read_exact` now returns
+  the wrapper structs `SerialDmaTx` and `SerialDmaRx` instead of the direct
+  DMA transfer struct. These allow checking the USART ISR events
+  with `is_event_triggered` as well.
+
+### Fixed
+
+- serial: The previous DMA `write_all` implementation did use the DMA transfer completion
+  event to check for transfer completion, but MCU datasheet specifies that the TC
+  flag of the USART peripheral should be checked for transfer completion to avoid
+  corruption of the last transfer. This is now done by the new `SerialDmaTx` wrapper.
+
+## Added
+
+- serial: Public `is_event_triggered` method which allows to check for events
+  given an event and a USART reference.
 
 ## [v0.9.1] - 2022-09-07
 

src/dma.rs

@@ -172,6 +172,11 @@ impl<B, C: Channel, T: Target> Transfer<B, C, T> {
 
         self.stop()
     }
+
+    pub(crate) fn target(&self) -> &T {
+        let inner = crate::unwrap!(self.inner.as_ref());
+        &inner.target
+    }
 }
 
 impl<B, C: Channel, T: Target> Drop for Transfer<B, C, T> {