Rework dma implementation

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
         with:
           toolchain: stable
           target: thumbv7em-none-eabihf
-      - run: cargo build --features=${{ matrix.mcu }} --lib --examples
+      - run: "cargo build --features=${{ matrix.mcu }}' rt ld cortex-m/critical-section-single-core' --lib --examples"
 
   check-minimal-feature-set:
     name: Check minimal feature set

Cargo.toml

@@ -51,10 +51,10 @@ cortex-m-semihosting = "0.5.0"
 defmt = "0.3.5"
 defmt-rtt = "0.4.0"
 defmt-test = "0.3.1"
-panic-probe = "0.3.1"
-panic-rtt-target = { version = "0.1.2", features = ["cortex-m"] }
+panic-probe = { version = "0.3.1", features = ["defmt", "print-defmt"] }
+panic-rtt-target = { version = "0.1.3" }
 panic-semihosting = "0.6.0"
-rtt-target = { version = "0.4.0" }
+rtt-target = "0.5.0"
 systick-monotonic = "1.0"
 usb-device = "0.3.1"
 usbd-serial = "0.2.0"

examples/serial_dma.rs

@@ -5,7 +5,8 @@
 #![no_std]
 #![no_main]
 
-use panic_semihosting as _;
+use defmt_rtt as _;
+use panic_probe as _;
 
 use cortex_m::{asm, singleton};
 use cortex_m_rt::entry;
@@ -40,8 +41,7 @@ fn main() -> ! {
             .pa10
             .into_af_push_pull(&mut gpioa.moder, &mut gpioa.otyper, &mut gpioa.afrh),
     );
-    let serial = Serial::new(dp.USART1, pins, 9600.Bd(), clocks, &mut rcc.apb2);
-    let (tx, rx) = serial.split();
+    let mut serial = Serial::new(dp.USART1, pins, 9600.Bd(), clocks, &mut rcc.apb2);
 
     let dma1 = dp.DMA1.split(&mut rcc.ahb);
 
@@ -50,30 +50,29 @@ fn main() -> ! {
     // the buffer we are going to receive the transmitted data in
     let rx_buf = singleton!(: [u8; 9] = [0; 9]).unwrap();
 
+    // TODO: where to find this information and bind this information to serial implementation
     // DMA channel selection depends on the peripheral:
     // - USART1: TX = 4, RX = 5
     // - USART2: TX = 6, RX = 7
     // - USART3: TX = 3, RX = 2
     let (tx_channel, rx_channel) = (dma1.ch4, dma1.ch5);
 
     // start separate DMAs for sending and receiving the data
-    let sending = tx.write_all(tx_buf, tx_channel);
-    let receiving = rx.read_exact(rx_buf, rx_channel);
+    let transfer = serial.transfer_exact(rx_buf, tx_channel, tx_buf, rx_channel);
 
     // block until all data was transmitted and received
-    let (tx_buf, tx_channel, tx) = sending.wait();
-    let (rx_buf, rx_channel, rx) = receiving.wait();
+    let ((rx_buf, tx_buf), (rx_channel, tx_channel)) = transfer.wait();
+    // let transfer = serial.read_exact(rx_buf, rx_channel);
+    // let (rx_buf, rx_channel) = transfer.wait();
 
     assert_eq!(tx_buf, rx_buf);
 
     // After a transfer is finished its parts can be re-used for another one.
     tx_buf.copy_from_slice(b"hi again!");
 
-    let sending = tx.write_all(tx_buf, tx_channel);
-    let receiving = rx.read_exact(rx_buf, rx_channel);
+    let transfer = serial.transfer_exact(rx_buf, rx_channel, tx_buf, tx_channel);
 
-    let (tx_buf, ..) = sending.wait();
-    let (rx_buf, ..) = receiving.wait();
+    let ((rx_buf, tx_buf), _) = transfer.wait();
 
     assert_eq!(tx_buf, rx_buf);
 

src/dma.rs

@@ -48,18 +48,22 @@ pub trait Target {
 /// An in-progress one-shot DMA transfer
 #[derive(Debug)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-pub struct Transfer<B, C: Channel, T: Target> {
+pub struct Transfer<'t, B, C, T>
+where
+    // C: Channel,
+    T: 't + Target,
+{
     // This is always a `Some` outside of `drop`.
-    inner: Option<TransferInner<B, C, T>>,
+    inner: Option<TransferInner<'t, B, C, T>>,
 }
 
-impl<B, C: Channel, T: Target> Transfer<B, C, T> {
+impl<'t, B, C: Channel, T: Target> Transfer<'t, B, C, T> {
     /// Start a DMA write transfer.
     ///
     /// # Panics
     ///
     /// Panics if the buffer is longer than 65535 words.
-    pub fn start_write(mut buffer: B, mut channel: C, target: T) -> Self
+    pub fn start_write(mut buffer: B, mut channel: C, target: &'t mut T) -> Self
     where
         B: WriteBuffer + 'static,
         T: OnChannel<C>,
@@ -91,7 +95,7 @@ impl<B, C: Channel, T: Target> Transfer<B, C, T> {
     /// # Panics
     ///
     /// Panics if the buffer is longer than 65535 words.
-    pub fn start_read(buffer: B, mut channel: C, target: T) -> Self
+    pub fn start_read(buffer: B, mut channel: C, target: &'t mut T) -> Self
     where
         B: ReadBuffer + 'static,
         T: OnChannel<C>,
@@ -124,7 +128,7 @@ impl<B, C: Channel, T: Target> Transfer<B, C, T> {
     ///
     /// - the given buffer will be valid for the duration of the transfer
     /// - the DMA channel is configured correctly for the given target and buffer
-    unsafe fn start(buffer: B, mut channel: C, mut target: T) -> Self
+    unsafe fn start(buffer: B, mut channel: C, target: &'t mut T) -> Self
     where
         T: OnChannel<C>,
     {
@@ -159,39 +163,151 @@ impl<B, C: Channel, T: Target> Transfer<B, C, T> {
     /// # Panics
     ///
     /// Panics no transfer is ongoing.
-    pub fn stop(mut self) -> (B, C, T) {
+    pub fn stop(mut self) -> (B, C) {
         let mut inner = crate::unwrap!(self.inner.take());
         inner.stop();
 
-        (inner.buffer, inner.channel, inner.target)
+        (inner.buffer, inner.channel)
     }
 
     /// Block until this transfer is done and return ownership over its parts
-    pub fn wait(self) -> (B, C, T) {
+    pub fn wait(self) -> (B, C) {
         while !self.is_complete() {}
 
         self.stop()
     }
 }
 
-impl<B, C: Channel, T: Target> Drop for Transfer<B, C, T> {
-    fn drop(&mut self) {
-        if let Some(inner) = self.inner.as_mut() {
-            inner.stop();
+impl<'t, BR, BW, CR, CW, T> Transfer<'t, (BR, BW), (CR, CW), T>
+where
+    CR: Channel, /*  + ReceiveChannel */
+    CW: Channel, /*  + TransmitChannel */
+    T: Target,
+{
+    /// Start a DMA write transfer.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the buffer is longer than 65535 words.
+    // TODO: sort arguments (target at first, write at first (see embedded hal?))
+    pub fn start_transfer(
+        buffer_read: BR,
+        mut buffer_write: BW,
+        mut channel_read: CR,
+        mut channel_write: CW,
+        target: &'t mut T,
+    ) -> Self
+    where
+        BR: ReadBuffer + 'static,
+        BW: WriteBuffer + 'static,
+        T: OnChannel<CR> + OnChannel<CW>,
+    {
+        // TODO: ensure same buffer length
+        // TODO: ensure same nord type
+
+        // SAFETY: We don't know the concrete type of `buffer` here, all
+        // we can use are its `WriteBuffer` methods. Hence the only `&mut self`
+        // method we can call is `write_buffer`, which is allowed by
+        // `WriteBuffer`'s safety requirements.
+        let (ptr, len) = unsafe { buffer_write.write_buffer() };
+        let len = crate::expect!(u16::try_from(len).ok(), "buffer is too large");
+
+        // SAFETY: We are using the address of a 'static WriteBuffer here,
+        // which is guaranteed to be safe for DMA.
+        unsafe { channel_write.set_memory_address(ptr as u32, Increment::Enable) };
+        channel_write.set_transfer_length(len);
+        channel_write.set_word_size::<BW::Word>();
+        channel_write.set_direction(Direction::FromPeripheral);
+
+        // SAFETY: We don't know the concrete type of `buffer` here, all
+        // we can use are its `ReadBuffer` methods. Hence there are no
+        // `&mut self` methods we can call, so we are safe according to
+        // `ReadBuffer`'s safety requirements.
+        let (ptr, len) = unsafe { buffer_read.read_buffer() };
+        let len = crate::expect!(u16::try_from(len).ok(), "buffer is too large");
+
+        // SAFETY: We are using the address of a 'static ReadBuffer here,
+        // which is guaranteed to be safe for DMA.
+        unsafe { channel_read.set_memory_address(ptr as u32, Increment::Enable) };
+        channel_read.set_transfer_length(len);
+        channel_read.set_word_size::<BR::Word>();
+        channel_read.set_direction(Direction::FromMemory);
+
+        crate::assert!(!channel_read.is_enabled() && !channel_write.is_enabled());
+
+        atomic::compiler_fence(Ordering::Release);
+
+        target.enable_dma();
+        channel_read.enable();
+        channel_write.enable();
+
+        Self {
+            inner: Some(TransferInner {
+                buffer: (buffer_read, buffer_write),
+                channel: (channel_read, channel_write),
+                target,
+            }),
         }
     }
+
+    /// Is this transfer complete?
+    ///
+    /// # Panics
+    ///
+    /// Panics if no transfer is ongoing.
+    pub fn is_complete(&self) -> bool {
+        let inner = crate::unwrap!(self.inner.as_ref());
+        defmt::dbg!(inner.channel.0.is_event_triggered(Event::Any));
+        defmt::dbg!(inner.channel.1.is_event_triggered(Event::Any));
+        inner.channel.0.is_event_triggered(Event::TransferComplete)
+            && inner.channel.1.is_event_triggered(Event::TransferComplete)
+    }
+
+    /// Stop this transfer and return ownership over its parts
+    ///
+    /// # Panics
+    ///
+    /// Panics no transfer is ongoing.
+    pub fn stop(mut self) -> ((BR, BW), (CR, CW)) {
+        let mut inner = crate::unwrap!(self.inner.take());
+        inner.stop();
+
+        (inner.buffer, inner.channel)
+    }
+
+    /// Block until this transfer is done and return ownership over its parts
+    pub fn wait(self) -> ((BR, BW), (CR, CW)) {
+        defmt::dbg!(self.inner.as_ref().unwrap().channel.0.is_enabled());
+        defmt::dbg!(self.inner.as_ref().unwrap().channel.1.is_enabled());
+        while !self.is_complete() {}
+
+        self.stop()
+    }
 }
 
+// TODO: Use different drops in case of one or both channels
+// impl<'t, B, C, T> Drop for Transfer<'t, B, C, T>
+// where
+//     C: Channel,
+//     T: Target,
+// {
+//     fn drop(&mut self) {
+//         if let Some(inner) = self.inner.as_mut() {
+//             inner.stop();
+//         }
+//     }
+// }
+
 /// This only exists so we can implement `Drop` for `Transfer`.
 #[derive(Debug)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-struct TransferInner<B, C, T> {
+struct TransferInner<'t, B, C, T> {
     buffer: B,
     channel: C,
-    target: T,
+    target: &'t mut T,
 }
 
-impl<B, C: Channel, T: Target> TransferInner<B, C, T> {
+impl<'t, B, C: Channel, T: Target> TransferInner<'t, B, C, T> {
     /// Stop this transfer
     fn stop(&mut self) {
         self.channel.disable();
@@ -201,6 +317,22 @@ impl<B, C: Channel, T: Target> TransferInner<B, C, T> {
     }
 }
 
+impl<'t, B, CR, CW, T> TransferInner<'t, B, (CR, CW), T>
+where
+    CR: Channel,
+    CW: Channel,
+    T: Target,
+{
+    /// Stop this transfer
+    fn stop(&mut self) {
+        self.channel.0.disable();
+        self.channel.1.disable();
+        self.target.disable_dma();
+
+        atomic::compiler_fence(Ordering::SeqCst);
+    }
+}
+
 /// DMA address increment mode
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -405,7 +537,7 @@ pub trait Channel: private::Channel {
     }
 
     /// Enable or disable the interrupt for the specified [`Event`].
-    fn configure_intterupt(&mut self, event: Event, enable: bool) {
+    fn configure_interrupt(&mut self, event: Event, enable: bool) {
         match event {
             Event::HalfTransfer => self.ch().cr.modify(|_, w| w.htie().bit(enable)),
             Event::TransferComplete => self.ch().cr.modify(|_, w| w.tcie().bit(enable)),
@@ -420,12 +552,12 @@ pub trait Channel: private::Channel {
 
     /// Enable the interrupt for the given [`Event`].
     fn enable_interrupt(&mut self, event: Event) {
-        self.configure_intterupt(event, true);
+        self.configure_interrupt(event, true);
     }
 
     /// Disable the interrupt for the given [`Event`].
     fn disable_interrupt(&mut self, event: Event) {
-        self.configure_intterupt(event, false);
+        self.configure_interrupt(event, false);
     }
 
     /// Start a transfer
@@ -582,6 +714,10 @@ dma!( 2: { 1,2,3,4,5 } );
 
 /// Marker trait mapping DMA targets to their channels
 pub trait OnChannel<C: Channel>: Target + crate::private::Sealed {}
+// TODO: put this in serial mod
+// TODO: the naming is switched
+pub trait TransmitChannel: crate::private::Sealed {}
+pub trait ReceiveChannel: crate::private::Sealed {}
 
 macro_rules! on_channel {
     (
@@ -594,6 +730,11 @@ macro_rules! on_channel {
                 impl<Tx, Rx> crate::private::Sealed for serial::Serial<$USART, (Tx, Rx)> {}
                 impl<Tx, Rx> OnChannel<$dma::$TxChannel> for serial::Serial<$USART, (Tx, Rx)> {}
                 impl<Tx, Rx> OnChannel<$dma::$RxChannel> for serial::Serial<$USART, (Tx, Rx)> {}
+
+                impl crate::private::Sealed for $dma::$TxChannel {}
+                impl TransmitChannel for $dma::$TxChannel {}
+                impl crate::private::Sealed for $dma::$RxChannel {}
+                impl ReceiveChannel for $dma::$RxChannel {}
             )+
         )+
     };