From f3fba80a713b632bee7190db8105065864518028 Mon Sep 17 00:00:00 2001
From: Nic0w <nico.broquet@gmail.com>
Date: Mon, 26 Apr 2021 22:05:37 +0200
Subject: [PATCH] Implement embedded_hal::serial traits for the UART.

---
 rp2040-hal/src/lib.rs    |  1 +
 rp2040-hal/src/serial.rs | 50 ++++++++++++++++++++++++++++++++++++++++
 rp2040-hal/src/uart.rs   | 16 +++++++++----
 3 files changed, 63 insertions(+), 4 deletions(-)
 create mode 100644 rp2040-hal/src/serial.rs

diff --git a/rp2040-hal/src/lib.rs b/rp2040-hal/src/lib.rs
index e8d96e2..00be8ba 100644
--- a/rp2040-hal/src/lib.rs
+++ b/rp2040-hal/src/lib.rs
@@ -23,4 +23,5 @@ pub mod ssi;
 pub mod timer;
 pub mod uart;
 pub mod usb;
+pub mod serial;
 pub mod watchdog;
diff --git a/rp2040-hal/src/serial.rs b/rp2040-hal/src/serial.rs
new file mode 100644
index 0000000..c7a3a2e
--- /dev/null
+++ b/rp2040-hal/src/serial.rs
@@ -0,0 +1,50 @@
+//! Implementation for the embedded_hal::serial traits for the UART.
+// See [embedded-hal](https://docs.rs/embedded-hal/0.2.4/embedded_hal/serial/index.html) for more details
+
+use core::convert::Infallible;
+
+use crate::uart::{
+    UARTPeripheral,
+    UARTDevice,
+    Enabled
+};
+
+use embedded_hal::serial::{
+    Read,
+    Write
+};
+
+use nb::Error::WouldBlock;
+
+impl<D: UARTDevice> Read<u8> for UARTPeripheral<Enabled, D> {
+    type Error = Infallible;
+
+    fn read(&mut self) -> nb::Result<u8, Self::Error> {
+
+        let byte: &mut [u8] = &mut [0; 1];
+
+        if let Err(_) = self.read_raw(byte) {
+            Err(WouldBlock)
+        }
+        else {
+            Ok(byte[0])
+        }
+    }
+}
+
+impl<D: UARTDevice> Write<u8> for UARTPeripheral<Enabled, D> {
+    type Error = Infallible;
+
+    fn write(&mut self, word: u8) -> nb::Result<(), Self::Error> {
+        if let Err(_) = self.write_raw(&[word]) {
+            Err(WouldBlock)
+        }
+        else {
+            Ok(())
+        }
+    }
+
+    fn flush(&mut self) -> nb::Result<(), Self::Error> {
+        self.transmit_flushed()
+    }
+}
diff --git a/rp2040-hal/src/uart.rs b/rp2040-hal/src/uart.rs
index a51c4d2..8860c4f 100644
--- a/rp2040-hal/src/uart.rs
+++ b/rp2040-hal/src/uart.rs
@@ -203,6 +203,14 @@ impl<D: UARTDevice> UARTPeripheral<Enabled, D> {
         self.transition(Disabled)
     }
 
+    pub(crate) fn transmit_flushed(&self) -> nb::Result<(), Infallible> {
+
+        if self.device.uartfr.read().txfe().bit_is_set() {
+            Ok(())
+        }
+        else { Err(WouldBlock) }
+    }
+
     fn uart_is_writable(&self) -> bool {
         self.device.uartfr.read().txff().bit_is_clear()
     }
@@ -216,7 +224,7 @@ impl<D: UARTDevice> UARTPeripheral<Enabled, D> {
     /// - 0 bytes were written, a WouldBlock Error is returned
     /// - some bytes were written, it is deemed to be a success
     /// Upon success, the number of written bytes is returned.
-    pub fn write<'d>(&self, data: &'d [u8]) -> nb::Result<&'d [u8], Infallible> {
+    pub fn write_raw <'d>(&self, data: &'d [u8]) -> nb::Result<&'d [u8], Infallible> {
 
         let mut bytes_written = 0;
 
@@ -246,7 +254,7 @@ impl<D: UARTDevice> UARTPeripheral<Enabled, D> {
     /// - 0 bytes were read, a WouldBlock Error is returned
     /// - some bytes were read, it is deemed to be a success
     /// Upon success, the number of read bytes is returned.
-    pub fn read<'b>(&self, buffer: &'b mut [u8]) -> nb::Result<&'b mut [u8], Infallible> {
+    pub fn read_raw<'b>(&self, buffer: &'b mut [u8]) -> nb::Result<&'b mut [u8], Infallible> {
 
         let mut bytes_read = 0;
 
@@ -277,7 +285,7 @@ impl<D: UARTDevice> UARTPeripheral<Enabled, D> {
         let mut temp = data;
 
         while !temp.is_empty() {
-            temp = match self.write(temp) {
+            temp = match self.write_raw(temp) {
                 Ok(remaining) => remaining,
                 Err(WouldBlock) => continue,
                 Err(_) => unreachable!()
@@ -291,7 +299,7 @@ impl<D: UARTDevice> UARTPeripheral<Enabled, D> {
         let mut offset = 0;
 
         while offset != buffer.len() {
-            offset += match self.read(&mut buffer[offset..]) {
+            offset += match self.read_raw(&mut buffer[offset..]) {
                 Ok(remaining) => { remaining.len() },
                 Err(WouldBlock) => continue,
                 Err(_) => unreachable!()