Remove the single byte read/write inherent functions (#2915)

* SPI: remove read/write_byte functions

* UART: make read/write_byte functions private

* changelog

* migration guide

* fix ieee802154_sniffer example

* review comments and cleanup

* use variable name buf instead of buff

* add pub fn read_bytes

* migration guide update

* another migration guide update

* improve docs of read/write_bytes

esp-hal/CHANGELOG.md

@@ -131,6 +131,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `DmaTxBuf::{compute_chunk_size, compute_descriptor_count, new_with_block_size}` (#2543)
 
 - The `prelude` module has been removed (#2845)
+- SPI: Removed `pub fn read_byte` and `pub fn write_byte` (#2915)
 
 - Removed all peripheral instance type parameters and `new_typed` constructors (#2907)
 
@@ -200,6 +201,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Many peripherals are now disabled by default and also get disabled when the driver is dropped (#2544)
 
 - Config: Crate prefixes and configuration keys are now separated by `_CONFIG_` (#2848)
+- UART: `read_byte` and `write_byte` made private. (#2915)
 
 ### Fixed
 

esp-hal/MIGRATING-0.22.md

@@ -429,6 +429,18 @@ e.g.
 +     .with_tx(peripherals.GPIO2);
 ```
 
+`write_byte` and `read_byte` have been removed.
+
+e.g.
+
+```dif
+- while let nb::Result::Ok(_c) = serial.read_byte() {
+-     cnt += 1;
+- }
++ let mut buff = [0u8; 64];
++ let cnt = serial.read_bytes(&mut buff);
+```
+
 ## Spi `with_miso` has been split
 
 Previously, `with_miso` set up the provided pin as an input and output, which was necessary for half duplex.
@@ -466,6 +478,15 @@ The Address and Command enums have similarly had their variants changed from e.g
 + Command::_1Bit
 ```
 
+`write_byte` and `read_byte` were removed and `write_bytes` and `read_bytes` can be used as replacement.
+
+e.g.
+
+```rust
+let mut byte = [0u8; 1];
+spi.read_bytes(&mut byte);
+```
+
 ## GPIO Changes
 
 The GPIO drive strength variants are renamed from e.g. `I5mA` to `_5mA`.

esp-hal/src/spi/master.rs

@@ -505,21 +505,8 @@ where
         }
     }
 
-    /// Read a byte from SPI.
-    ///
-    /// Sends out a stuffing byte for every byte to read. This function doesn't
-    /// perform flushing. If you want to read the response to something you
-    /// have written before, consider using [`Self::transfer`] instead.
-    pub fn read_byte(&mut self) -> nb::Result<u8, Error> {
-        self.driver().read_byte()
-    }
-
-    /// Write a byte to SPI.
-    pub fn write_byte(&mut self, word: u8) -> nb::Result<(), Error> {
-        self.driver().write_byte(word)
-    }
-
-    /// Write bytes to SPI.
+    /// Write bytes to SPI. After writing, flush is called to ensure all data
+    /// has been transmitted.
     pub fn write_bytes(&mut self, words: &[u8]) -> Result<(), Error> {
         self.driver().write_bytes(words)?;
         self.driver().flush()?;
@@ -527,7 +514,13 @@ where
         Ok(())
     }
 
-    /// Sends `words` to the slave. Returns the `words` received from the slave
+    /// Read bytes from SPI. The provided slice is filled with data received
+    /// from the slave.
+    pub fn read_bytes(&mut self, words: &mut [u8]) -> Result<(), Error> {
+        self.driver().read_bytes(words)
+    }
+
+    /// Sends `words` to the slave. Returns the `words` received from the slave.
     pub fn transfer<'w>(&mut self, words: &'w mut [u8]) -> Result<&'w [u8], Error> {
         self.driver().transfer(words)
     }
@@ -2153,11 +2146,14 @@ mod ehal1 {
         Dm: DriverMode,
     {
         fn read(&mut self) -> nb::Result<u8, Self::Error> {
-            self.driver().read_byte()
+            let mut buffer = [0u8; 1];
+            self.driver().read_bytes(&mut buffer)?;
+            Ok(buffer[0])
         }
 
         fn write(&mut self, word: u8) -> nb::Result<(), Self::Error> {
-            self.driver().write_byte(word)
+            self.driver().write_bytes(&[word])?;
+            Ok(())
         }
     }
 
@@ -2926,30 +2922,6 @@ impl Driver {
         });
     }
 
-    fn read_byte(&self) -> nb::Result<u8, Error> {
-        if self.busy() {
-            return Err(nb::Error::WouldBlock);
-        }
-
-        let reg_block = self.register_block();
-        Ok(u32::try_into(reg_block.w(0).read().bits()).unwrap_or_default())
-    }
-
-    fn write_byte(&self, word: u8) -> nb::Result<(), Error> {
-        if self.busy() {
-            return Err(nb::Error::WouldBlock);
-        }
-
-        self.configure_datalen(0, 1);
-
-        let reg_block = self.register_block();
-        reg_block.w(0).write(|w| w.buf().set(word.into()));
-
-        self.start_operation();
-
-        Ok(())
-    }
-
     #[cfg_attr(place_spi_driver_in_ram, ram)]
     fn fill_fifo(&self, chunk: &[u8]) {
         // TODO: replace with `array_chunks` and `from_le_bytes`

esp-hal/src/uart.rs

@@ -80,7 +80,8 @@
 //!
 //! // Each component can be used individually to interact with the UART:
 //! tx.write_bytes(&[42u8]).expect("write error!");
-//! let byte = rx.read_byte().expect("read error!");
+//! let mut byte = [0u8; 1];
+//! rx.read_bytes(&mut byte);
 //! # }
 //! ```
 //! 
@@ -197,10 +198,8 @@
 //!         let mut serial = SERIAL.borrow_ref_mut(cs);
 //!         let serial = serial.as_mut().unwrap();
 //!
-//!         let mut cnt = 0;
-//!         while let nb::Result::Ok(_c) = serial.read_byte() {
-//!             cnt += 1;
-//!         }
+//!         let mut buf = [0u8; 64];
+//!         let cnt = serial.read_bytes(&mut buf);
 //!         writeln!(serial, "Read {} bytes", cnt).ok();
 //!
 //!         let pending_interrupts = serial.interrupts();
@@ -826,8 +825,8 @@ where
         self.uart.info().apply_config(config)
     }
 
-    /// Read a byte from the UART
-    pub fn read_byte(&mut self) -> nb::Result<u8, Error> {
+    // Read a byte from the UART
+    fn read_byte(&mut self) -> nb::Result<u8, Error> {
         cfg_if::cfg_if! {
             if #[cfg(esp32s2)] {
                 // On the ESP32-S2 we need to use PeriBus2 to read the FIFO:
@@ -1134,8 +1133,8 @@ where
         sync_regs(register_block);
     }
 
-    /// Write a byte out over the UART
-    pub fn write_byte(&mut self, word: u8) -> nb::Result<(), Error> {
+    // Write a byte out over the UART
+    fn write_byte(&mut self, word: u8) -> nb::Result<(), Error> {
         self.tx.write_byte(word)
     }
 
@@ -1144,8 +1143,8 @@ where
         self.tx.flush()
     }
 
-    /// Read a byte from the UART
-    pub fn read_byte(&mut self) -> nb::Result<u8, Error> {
+    // Read a byte from the UART
+    fn read_byte(&mut self) -> nb::Result<u8, Error> {
         self.rx.read_byte()
     }
 

examples/src/bin/ieee802154_sniffer.rs

@@ -39,12 +39,14 @@ fn main() -> ! {
     let mut cnt = 0;
     let mut read = [0u8; 2];
     loop {
-        let c = nb::block!(uart0.read_byte()).unwrap();
-        if c == b'r' {
+        let mut buf = [0u8; 1];
+        while uart0.read_bytes(&mut buf) == 0 {}
+
+        if buf[0] == b'r' {
             continue;
         }
 
-        read[cnt] = c;
+        read[cnt] = buf[0];
         cnt += 1;
 
         if cnt >= 2 {
@@ -74,10 +76,9 @@ fn main() -> ! {
             println!("@RAW {:02x?}", &frame.data);
         }
 
-        if let nb::Result::Ok(c) = uart0.read_byte() {
-            if c == b'r' {
-                software_reset();
-            }
+        let mut buf = [0u8; 1];
+        if uart0.read_bytes(&mut buf) > 0 && buf[0] == b'r' {
+            software_reset();
         }
     }
 }

hil-test/tests/uart_regression.rs

@@ -14,7 +14,6 @@ mod tests {
         uart::{self, UartRx, UartTx},
     };
     use hil_test as _;
-    use nb::block;
 
     #[test]
     fn test_that_creating_tx_does_not_cause_a_pulse() {
@@ -27,7 +26,8 @@ mod tests {
             .with_rx(rx);
 
         // start reception
-        _ = rx.read_byte(); // this will just return WouldBlock
+        let mut buf = [0u8; 1];
+        _ = rx.read_bytes(&mut buf); // this will just return WouldBlock
 
         unsafe { tx.set_output_high(false, esp_hal::Internal::conjure()) };
 
@@ -38,8 +38,8 @@ mod tests {
 
         tx.flush().unwrap();
         tx.write_bytes(&[0x42]).unwrap();
-        let read = block!(rx.read_byte());
+        while rx.read_bytes(&mut buf) == 0 {}
 
-        assert_eq!(read, Ok(0x42));
+        assert_eq!(buf[0], 0x42);
     }
 }

hil-test/tests/uart_tx_rx.rs

@@ -11,7 +11,6 @@ use esp_hal::{
     Blocking,
 };
 use hil_test as _;
-use nb::block;
 
 struct Context {
     rx: UartRx<'static, Blocking>,
@@ -45,9 +44,10 @@ mod tests {
 
         ctx.tx.flush().unwrap();
         ctx.tx.write_bytes(&byte).unwrap();
-        let read = block!(ctx.rx.read_byte());
+        let mut buf = [0u8; 1];
+        while ctx.rx.read_bytes(&mut buf) == 0 {}
 
-        assert_eq!(read, Ok(0x42));
+        assert_eq!(buf[0], 0x42);
     }
 
     #[test]