feat : Add async-io feature and embedded-io-async dependency

Added the async-io feature to Cargo.toml, enabling async support for UART and other modules.
Added embedded-io-async as an optional dependency, activated by the async-io feature.
Updated code to use feature gating for async implementations.

Author: rusty1968

Cargo.lock

@@ -21,6 +21,7 @@ test-rsa = []
 test-ecdsa = []
 test-hmac = []
 test-hash = []
+async-io = ["embedded-io-async"]
 
 [dependencies]
 ast1060-pac = { git = "https://github.com/rusty1968/ast1060-pac.git", features = ["rt"] }
@@ -35,3 +36,7 @@ cortex-m = { version = "0.7.5" }
 cortex-m-rt = { version = "0.6.5", features = ["device"] }
 panic-halt = "1.0.0"
 
+[dependencies.embedded-io-async]
+version = "0.6"
+optional = true
+

Cargo.toml

@@ -9,4 +9,7 @@ pub mod rsa;
 pub mod syscon;
 pub mod tests;
 pub mod uart;
+#[cfg(feature = "async-io")]
+pub mod uart_async;
+
 pub mod watchdog;

src/lib.rs

@@ -137,10 +137,16 @@ impl UartController<'_> {
         // Additional configurations can be added here
     }
 
+    /// Returns true if the Transmitter Holding Register (THR) is empty.
+    #[must_use]
+    pub fn is_thr_empty(&self) -> bool {
+        self.uart.uartlsr().read().thre().bit_is_set()
+    }
+
     /// Sends a byte using the FIFO.
     pub fn send_byte_fifo(&mut self, data: u8) {
         // Wait until the Transmitter Holding Register (THR) is empty
-        while self.uart.uartlsr().read().thre().bit_is_clear() {}
+        while !self.is_thr_empty() {}
 
         // Write the byte to the Transmit Holding Register (THR)
         self.uart
@@ -166,6 +172,25 @@ impl UartController<'_> {
 }
 
 impl<'a> UartController<'a> {
+    /// Reads a byte from the UART receiver buffer register (UARTRBR).
+    #[must_use]
+    pub fn read_rbr(&self) -> u8 {
+        self.uart.uartrbr().read().uartrbr().bits()
+    }
+
+    /// Returns true if data is available in the UART receiver buffer (DR bit is set).
+    #[must_use]
+    pub fn is_data_ready(&self) -> bool {
+        self.uart.uartlsr().read().dr().bit_is_set()
+    }
+
+    /// Writes a byte to the UART transmit holding register (THR).
+    pub fn write_thr(&mut self, byte: u8) {
+        self.uart
+            .uartthr()
+            .write(|w| unsafe { w.bits(u32::from(byte)) });
+    }
+
     // Wait until the Transmitter Holding Register (THR) is empty
     pub fn new(uart: Uart, delay: &'a mut dyn DelayNs) -> Self {
         Self { uart, delay }

src/uart.rs

@@ -0,0 +1,55 @@
+// Licensed under the Apache-2.0 license
+
+use ast1060_pac::Uart;
+
+use crate::uart::UartController;
+
+use core::future::poll_fn;
+use core::task::{Context, Poll};
+use embedded_io_async::{Read, Write};
+
+/// Async implementation of embedded_io_async::Read for UartController.
+///
+/// Reads bytes asynchronously from the UART receiver buffer.
+/// Waits until data is available before reading each byte.
+impl embedded_io_async::Read for UartController<'_> {
+    async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        let mut count = 0;
+        for byte in buf.iter_mut() {
+            poll_fn(|cx| {
+                if self.is_data_ready() {
+                    *byte = self.read_rbr();
+                    Poll::Ready(Ok(()))
+                } else {
+                    cx.waker().wake_by_ref();
+                    Poll::Pending
+                }
+            })
+            .await?;
+            count += 1;
+        }
+        Ok(count)
+    }
+}
+
+/// Async implementation of embedded_io_async::Write for UartController.
+///
+/// Writes bytes asynchronously to the UART transmit holding register.
+/// Waits until the transmitter is ready before sending each byte.
+impl embedded_io_async::Write for UartController<'_> {
+    async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        for &byte in buf {
+            poll_fn(|cx| {
+                if self.is_thr_empty() {
+                    self.write_thr(byte);
+                    Poll::Ready(Ok(()))
+                } else {
+                    cx.waker().wake_by_ref();
+                    Poll::Pending
+                }
+            })
+            .await?;
+        }
+        Ok(buf.len())
+    }
+}