Merge #545

545: Add adapter for implementing async traits for blocking types r=lulf a=lulf

This allows writing drivers relying on async traits, while still
functioning with implementations that already implement the embedded-hal
traits.

Co-authored-by: Ulf Lilleengen <lulf@redhat.com>

embassy-stm32/Cargo.toml

@@ -27,6 +27,7 @@ atomic-polyfill = "0.1.5"
 stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", features = ["rt"] }
 vcell = { version = "0.1.3", optional = true }
 bxcan = "0.6.2"
+nb = "1.0.0"
 
 seq-macro = "0.2.2"
 

embassy-stm32/src/usart/mod.rs

@@ -192,8 +192,35 @@ impl<'d, T: Instance, TxDma, RxDma> Uart<'d, T, TxDma, RxDma> {
     }
 }
 
-impl<'d, T: Instance, RxDma> embedded_hal::blocking::serial::Write<u8>
-    for Uart<'d, T, NoDma, RxDma>
+impl<'d, T: Instance, TxDma, RxDma> embedded_hal::serial::Read<u8> for Uart<'d, T, TxDma, RxDma> {
+    type Error = Error;
+    fn read(&mut self) -> Result<u8, nb::Error<Self::Error>> {
+        let r = self.inner.regs();
+        unsafe {
+            let sr = sr(r).read();
+            if sr.pe() {
+                rdr(r).read_volatile();
+                Err(nb::Error::Other(Error::Parity))
+            } else if sr.fe() {
+                rdr(r).read_volatile();
+                Err(nb::Error::Other(Error::Framing))
+            } else if sr.ne() {
+                rdr(r).read_volatile();
+                Err(nb::Error::Other(Error::Noise))
+            } else if sr.ore() {
+                rdr(r).read_volatile();
+                Err(nb::Error::Other(Error::Overrun))
+            } else if sr.rxne() {
+                Ok(rdr(r).read_volatile())
+            } else {
+                Err(nb::Error::WouldBlock)
+            }
+        }
+    }
+}
+
+impl<'d, T: Instance, TxDma, RxDma> embedded_hal::blocking::serial::Write<u8>
+    for Uart<'d, T, TxDma, RxDma>
 {
     type Error = Error;
     fn bwrite_all(&mut self, buffer: &[u8]) -> Result<(), Self::Error> {