Merge #1487

1487: rp: Implement embedded_hal::serial::Write for Uart/UartTx r=Dirbaio a=Alpha-3

Uart/UartTx currently implements `embedded_hal_02::serial::Read<u8>` and `embedded_hal_02::blocking::serial::Write<u8>` but not `embedded_hal_02::serial::Write<u8>`.

This implements the missing `embedded_hal_02::serial::Write<u8>` to allow use of Uart with crates that expect this interface, such as [defmt_serial](https://docs.rs/defmt-serial/latest/defmt_serial/).

Co-authored-by: Alpha3__0 <Alpha3.0gmail.com>

embassy-rp/src/uart/mod.rs

@@ -755,6 +755,32 @@ mod eh02 {
         }
     }
 
+    impl<'d, T: Instance, M: Mode> embedded_hal_02::serial::Write<u8> for UartTx<'d, T, M> {
+        type Error = Error;
+
+        fn write(&mut self, word: u8) -> Result<(), nb::Error<Self::Error>> {
+            let r = T::regs();
+            unsafe {
+                if r.uartfr().read().txff() {
+                    return Err(nb::Error::WouldBlock);
+                }
+
+                r.uartdr().write(|w| w.set_data(word));
+            }
+            Ok(())
+        }
+
+        fn flush(&mut self) -> Result<(), nb::Error<Self::Error>> {
+            let r = T::regs();
+            unsafe {
+                if !r.uartfr().read().txfe() {
+                    return Err(nb::Error::WouldBlock);
+                }
+            }
+            Ok(())
+        }
+    }
+
     impl<'d, T: Instance, M: Mode> embedded_hal_02::blocking::serial::Write<u8> for UartTx<'d, T, M> {
         type Error = Error;
 
@@ -775,6 +801,18 @@ mod eh02 {
         }
     }
 
+    impl<'d, T: Instance, M: Mode> embedded_hal_02::serial::Write<u8> for Uart<'d, T, M> {
+        type Error = Error;
+
+        fn write(&mut self, word: u8) -> Result<(), nb::Error<Self::Error>> {
+            embedded_hal_02::serial::Write::write(&mut self.tx, word)
+        }
+
+        fn flush(&mut self) -> Result<(), nb::Error<Self::Error>> {
+            embedded_hal_02::serial::Write::flush(&mut self.tx)
+        }
+    }
+
     impl<'d, T: Instance, M: Mode> embedded_hal_02::blocking::serial::Write<u8> for Uart<'d, T, M> {
         type Error = Error;