UART embedded-io fixes

Author: robamu

va108xx-hal/CHANGELOG.md

@@ -8,6 +8,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [unreleased]
 
+## [v0.11.1] 2025-03-10
+
+## Fixed
+
+- Fix `embedded_io` UART implementation to implement the documented contract properly.
+  The implementation will now block until at least one byte is available or can be written, unless
+  the send or receive buffer is empty.
+
 ## [v0.11.0] 2025-03-07
 
 ## Changed
@@ -253,6 +261,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - README with basic instructions how to set up own binary crate
 
 [unreleased]: https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/compare/va108xx-hal-v0.11.0...HEAD
+[v0.11.1]: https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/compare/va108xx-hal-v0.11.0...va108xx-hal-v0.11.1
 [v0.11.0]: https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/compare/va108xx-hal-v0.10.0...va108xx-hal-v0.11.0
 [v0.10.0]: https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/compare/va108xx-hal-v0.9.0...va108xx-hal-v0.10.0
 [v0.9.0]: https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/compare/va108xx-hal-v0.8.0...va108xx-hal-v0.9.0

va108xx-hal/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "va108xx-hal"
-version = "0.11.0"
+version = "0.11.1"
 authors = ["Robin Mueller <[email protected]>"]
 edition = "2021"
 description = "HAL for the Vorago VA108xx family of microcontrollers"

va108xx-hal/src/uart/mod.rs

@@ -892,7 +892,15 @@ impl<Uart: Instance> embedded_hal_nb::serial::Read<u8> for Rx<Uart> {
 
 impl<Uart: Instance> embedded_io::Read for Rx<Uart> {
     fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        if buf.is_empty() {
+            return Ok(0);
+        }
         let mut read = 0;
+        loop {
+            if self.0.rxstatus().read().rdavl().bit_is_set() {
+                break;
+            }
+        }
         for byte in buf.iter_mut() {
             match <Self as embedded_hal_nb::serial::Read<u8>>::read(self) {
                 Ok(w) => {
@@ -1058,6 +1066,14 @@ impl<Uart: Instance> embedded_hal_nb::serial::Write<u8> for Tx<Uart> {
 
 impl<Uart: Instance> embedded_io::Write for Tx<Uart> {
     fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        if buf.is_empty() {
+            return Ok(0);
+        }
+        loop {
+            if self.0.txstatus().read().wrrdy().bit_is_set() {
+                break;
+            }
+        }
         let mut written = 0;
         for byte in buf.iter() {
             match <Self as embedded_hal_nb::serial::Write<u8>>::write(self, *byte) {
@@ -1066,7 +1082,7 @@ impl<Uart: Instance> embedded_io::Write for Tx<Uart> {
             }
         }
 
-        Ok(buf.len())
+        Ok(written)
     }
 
     fn flush(&mut self) -> Result<(), Self::Error> {