3 files changed, 279 insertions, 86 deletions

diff --git a/embassy-stm32/src/i2s.rs b/embassy-stm32/src/i2s.rs
index 094de2461..f11371f98 100644
--- a/embassy-stm32/src/i2s.rs
+++ b/embassy-stm32/src/i2s.rs
@@ -1,12 +1,13 @@
 //! Inter-IC Sound (I2S)
 
+use embassy_futures::join::join;
 use embassy_hal_internal::into_ref;
+use stm32_metapac::spi::vals;
 
-use crate::dma::ChannelAndRequest;
+use crate::dma::{ringbuffer, ChannelAndRequest, ReadableRingBuffer, TransferOptions, WritableRingBuffer};
 use crate::gpio::{AfType, AnyPin, OutputType, SealedPin, Speed};
 use crate::mode::Async;
-use crate::pac::spi::vals;
-use crate::spi::{Config as SpiConfig, *};
+use crate::spi::{Config as SpiConfig, RegsExt as _, *};
 use crate::time::Hertz;
 use crate::{Peripheral, PeripheralRef};
 
@@ -19,6 +20,19 @@ pub enum Mode {
     Slave,
 }
 
+/// I2S function
+#[derive(Copy, Clone)]
+#[allow(dead_code)]
+enum Function {
+    /// Transmit audio data
+    Transmit,
+    /// Receive audio data
+    Receive,
+    #[cfg(spi_v3)]
+    /// Transmit and Receive audio data
+    FullDuplex,
+}
+
 /// I2C standard
 #[derive(Copy, Clone)]
 pub enum Standard {
@@ -34,6 +48,30 @@ pub enum Standard {
     PcmShortSync,
 }
 
+/// SAI error
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Error {
+    /// `write` called on a SAI in receive mode.
+    NotATransmitter,
+    /// `read` called on a SAI in transmit mode.
+    NotAReceiver,
+    /// Overrun
+    Overrun,
+}
+
+impl From<ringbuffer::Error> for Error {
+    fn from(#[allow(unused)] err: ringbuffer::Error) -> Self {
+        #[cfg(feature = "defmt")]
+        {
+            if err == ringbuffer::Error::DmaUnsynced {
+                defmt::error!("Ringbuffer broken invariants detected!");
+            }
+        }
+        Self::Overrun
+    }
+}
+
 impl Standard {
     #[cfg(any(spi_v1, spi_v3, spi_f1))]
     const fn i2sstd(&self) -> vals::I2sstd {
@@ -142,31 +180,62 @@ impl Default for Config {
     }
 }
 
+/// I2S driver writer. Useful for moving write functionality across tasks.
+pub struct Writer<'s, 'd, W: Word>(&'s mut WritableRingBuffer<'d, W>);
+
+impl<'s, 'd, W: Word> Writer<'s, 'd, W> {
+    /// Write data to the I2S ringbuffer.
+    /// This appends the data to the buffer and returns immediately. The data will be transmitted in the background.
+    /// If thfre’s no space in the buffer, this waits until there is.
+    pub async fn write(&mut self, data: &[W]) -> Result<(), Error> {
+        self.0.write_exact(data).await?;
+        Ok(())
+    }
+
+    /// Reset the ring buffer to its initial state.
+    /// Can be used to recover from overrun.
+    /// The ringbuffer will always auto-reset on Overrun in any case.
+    pub fn reset(&mut self) {
+        self.0.clear();
+    }
+}
+
+/// I2S driver reader. Useful for moving read functionality across tasks.
+pub struct Reader<'s, 'd, W: Word>(&'s mut ReadableRingBuffer<'d, W>);
+
+impl<'s, 'd, W: Word> Reader<'s, 'd, W> {
+    /// Read data from the I2S ringbuffer.
+    /// SAI is always receiving data in the background. This function pops already-received data from the buffer.
+    /// If there’s less than data.len() data in the buffer, this waits until there is.
+    pub async fn read(&mut self, data: &mut [W]) -> Result<(), Error> {
+        self.0.read_exact(data).await?;
+        Ok(())
+    }
+
+    /// Reset the ring buffer to its initial state.
+    /// Can be used to prevent overrun.
+    /// The ringbuffer will always auto-reset on Overrun in any case.
+    pub fn reset(&mut self) {
+        self.0.clear();
+    }
+}
+
 /// I2S driver.
-pub struct I2S<'d> {
-    _peri: Spi<'d, Async>,
+pub struct I2S<'d, W: Word> {
+    #[allow(dead_code)]
+    mode: Mode,
+    spi: Spi<'d, Async>,
     txsd: Option<PeripheralRef<'d, AnyPin>>,
     rxsd: Option<PeripheralRef<'d, AnyPin>>,
     ws: Option<PeripheralRef<'d, AnyPin>>,
     ck: Option<PeripheralRef<'d, AnyPin>>,
     mck: Option<PeripheralRef<'d, AnyPin>>,
+    tx_ring_buffer: Option<WritableRingBuffer<'d, W>>,
+    rx_ring_buffer: Option<ReadableRingBuffer<'d, W>>,
 }
 
-/// I2S function
-#[derive(Copy, Clone)]
-#[allow(dead_code)]
-enum Function {
-    /// Transmit audio data
-    Transmit,
-    /// Receive audio data
-    Receive,
-    #[cfg(spi_v3)]
-    /// Transmit and Receive audio data
-    FullDuplex,
-}
-
-impl<'d> I2S<'d> {
-    /// Create a transmitter driver
+impl<'d, W: Word> I2S<'d, W> {
+    /// Create a transmitter driver.
     pub fn new_txonly<T: Instance>(
         peri: impl Peripheral<P = T> + 'd,
         sd: impl Peripheral<P = impl MosiPin<T>> + 'd,
@@ -174,18 +243,18 @@ impl<'d> I2S<'d> {
         ck: impl Peripheral<P = impl CkPin<T>> + 'd,
         mck: impl Peripheral<P = impl MckPin<T>> + 'd,
         txdma: impl Peripheral<P = impl TxDma<T>> + 'd,
+        txdma_buf: &'d mut [W],
         freq: Hertz,
         config: Config,
     ) -> Self {
-        into_ref!(sd);
         Self::new_inner(
             peri,
             new_pin!(sd, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
             None,
             ws,
             ck,
-            mck,
-            new_dma!(txdma),
+            new_pin!(mck, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
+            new_dma!(txdma).map(|d| (d, txdma_buf)),
             None,
             freq,
             config,
@@ -193,42 +262,61 @@ impl<'d> I2S<'d> {
         )
     }
 
-    /// Create a receiver driver
+    /// Create a transmitter driver without a master clock pin.
+    pub fn new_txonly_nomck<T: Instance>(
+        peri: impl Peripheral<P = T> + 'd,
+        sd: impl Peripheral<P = impl MosiPin<T>> + 'd,
+        ws: impl Peripheral<P = impl WsPin<T>> + 'd,
+        ck: impl Peripheral<P = impl CkPin<T>> + 'd,
+        txdma: impl Peripheral<P = impl TxDma<T>> + 'd,
+        txdma_buf: &'d mut [W],
+        freq: Hertz,
+        config: Config,
+    ) -> Self {
+        Self::new_inner(
+            peri,
+            new_pin!(sd, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
+            None,
+            ws,
+            ck,
+            None,
+            new_dma!(txdma).map(|d| (d, txdma_buf)),
+            None,
+            freq,
+            config,
+            Function::Transmit,
+        )
+    }
+
+    /// Create a receiver driver.
     pub fn new_rxonly<T: Instance>(
         peri: impl Peripheral<P = T> + 'd,
         sd: impl Peripheral<P = impl MisoPin<T>> + 'd,
         ws: impl Peripheral<P = impl WsPin<T>> + 'd,
         ck: impl Peripheral<P = impl CkPin<T>> + 'd,
         mck: impl Peripheral<P = impl MckPin<T>> + 'd,
-        #[cfg(not(spi_v3))] txdma: impl Peripheral<P = impl TxDma<T>> + 'd,
         rxdma: impl Peripheral<P = impl RxDma<T>> + 'd,
+        rxdma_buf: &'d mut [W],
         freq: Hertz,
         config: Config,
     ) -> Self {
-        into_ref!(sd);
         Self::new_inner(
             peri,
             None,
             new_pin!(sd, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
             ws,
             ck,
-            mck,
-            #[cfg(not(spi_v3))]
-            new_dma!(txdma),
-            #[cfg(spi_v3)]
+            new_pin!(mck, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
             None,
-            new_dma!(rxdma),
+            new_dma!(rxdma).map(|d| (d, rxdma_buf)),
             freq,
             config,
-            #[cfg(not(spi_v3))]
-            Function::Transmit,
-            #[cfg(spi_v3)]
             Function::Receive,
         )
     }
 
     #[cfg(spi_v3)]
-    /// Create a full duplex transmitter driver
+    /// Create a full duplex driver.
     pub fn new_full_duplex<T: Instance>(
         peri: impl Peripheral<P = T> + 'd,
         txsd: impl Peripheral<P = impl MosiPin<T>> + 'd,
@@ -237,44 +325,144 @@ impl<'d> I2S<'d> {
         ck: impl Peripheral<P = impl CkPin<T>> + 'd,
         mck: impl Peripheral<P = impl MckPin<T>> + 'd,
         txdma: impl Peripheral<P = impl TxDma<T>> + 'd,
+        txdma_buf: &'d mut [W],
         rxdma: impl Peripheral<P = impl RxDma<T>> + 'd,
+        rxdma_buf: &'d mut [W],
         freq: Hertz,
         config: Config,
     ) -> Self {
-        into_ref!(txsd, rxsd);
         Self::new_inner(
             peri,
             new_pin!(txsd, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
             new_pin!(rxsd, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
             ws,
             ck,
-            mck,
-            new_dma!(txdma),
-            new_dma!(rxdma),
+            new_pin!(mck, AfType::output(OutputType::PushPull, Speed::VeryHigh)),
+            new_dma!(txdma).map(|d| (d, txdma_buf)),
+            new_dma!(rxdma).map(|d| (d, rxdma_buf)),
             freq,
             config,
             Function::FullDuplex,
         )
     }
 
-    /// Write audio data.
-    pub async fn read<W: Word>(&mut self, data: &mut [W]) -> Result<(), Error> {
-        self._peri.read(data).await
+    /// Start I2S driver.
+    pub fn start(&mut self) {
+        self.spi.info.regs.cr1().modify(|w| {
+            w.set_spe(false);
+        });
+        self.spi.set_word_size(W::CONFIG);
+        if let Some(tx_ring_buffer) = &mut self.tx_ring_buffer {
+            tx_ring_buffer.start();
+
+            set_txdmaen(self.spi.info.regs, true);
+        }
+        if let Some(rx_ring_buffer) = &mut self.rx_ring_buffer {
+            rx_ring_buffer.start();
+            // SPIv3 clears rxfifo on SPE=0
+            #[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
+            flush_rx_fifo(self.spi.info.regs);
+
+            set_rxdmaen(self.spi.info.regs, true);
+        }
+        self.spi.info.regs.cr1().modify(|w| {
+            w.set_spe(true);
+        });
+        #[cfg(any(spi_v3, spi_v4, spi_v5))]
+        self.spi.info.regs.cr1().modify(|w| {
+            w.set_cstart(true);
+        });
+    }
+
+    /// Reset the ring buffer to its initial state.
+    /// Can be used to recover from overrun.
+    pub fn clear(&mut self) {
+        if let Some(rx_ring_buffer) = &mut self.rx_ring_buffer {
+            rx_ring_buffer.clear();
+        }
+        if let Some(tx_ring_buffer) = &mut self.tx_ring_buffer {
+            tx_ring_buffer.clear();
+        }
+    }
+
+    /// Stop I2S driver.
+    pub async fn stop(&mut self) {
+        let regs = self.spi.info.regs;
+
+        let tx_f = async {
+            if let Some(tx_ring_buffer) = &mut self.tx_ring_buffer {
+                tx_ring_buffer.stop().await;
+
+                set_txdmaen(regs, false);
+            }
+        };
+
+        let rx_f = async {
+            if let Some(rx_ring_buffer) = &mut self.rx_ring_buffer {
+                rx_ring_buffer.stop().await;
+
+                set_rxdmaen(regs, false);
+            }
+        };
+
+        join(rx_f, tx_f).await;
+
+        #[cfg(any(spi_v3, spi_v4, spi_v5))]
+        {
+            if let Mode::Master = self.mode {
+                regs.cr1().modify(|w| {
+                    w.set_csusp(true);
+                });
+
+                while regs.cr1().read().cstart() {}
+            }
+        }
+
+        regs.cr1().modify(|w| {
+            w.set_spe(false);
+        });
+
+        self.clear();
+    }
+
+    /// Split the driver into a Reader/Writer pair.
+    /// Useful for splitting the reader/writer functionality across tasks or
+    /// for calling the read/write methods in parallel.
+    pub fn split<'s>(&'s mut self) -> Result<(Reader<'s, 'd, W>, Writer<'s, 'd, W>), Error> {
+        match (&mut self.rx_ring_buffer, &mut self.tx_ring_buffer) {
+            (None, _) => Err(Error::NotAReceiver),
+            (_, None) => Err(Error::NotATransmitter),
+            (Some(rx_ring), Some(tx_ring)) => Ok((Reader(rx_ring), Writer(tx_ring))),
+        }
     }
 
-    /// Write audio data.
-    pub async fn write<W: Word>(&mut self, data: &[W]) -> Result<(), Error> {
-        self._peri.write(data).await
+    /// Read data from the I2S ringbuffer.
+    /// SAI is always receiving data in the background. This function pops already-received data from the buffer.
+    /// If there’s less than data.len() data in the buffer, this waits until there is.
+    pub async fn read(&mut self, data: &mut [W]) -> Result<(), Error> {
+        match &mut self.rx_ring_buffer {
+            Some(ring) => Reader(ring).read(data).await,
+            _ => Err(Error::NotAReceiver),
+        }
     }
 
-    /// Transfer audio data.
-    pub async fn transfer<W: Word>(&mut self, read: &mut [W], write: &[W]) -> Result<(), Error> {
-        self._peri.transfer(read, write).await
+    /// Write data to the I2S ringbuffer.
+    /// This appends the data to the buffer and returns immediately. The data will be transmitted in the background.
+    /// If thfre’s no space in the buffer, this waits until there is.
+    pub async fn write(&mut self, data: &[W]) -> Result<(), Error> {
+        match &mut self.tx_ring_buffer {
+            Some(ring) => Writer(ring).write(data).await,
+            _ => Err(Error::NotATransmitter),
+        }
     }
 
-    /// Transfer audio data in place.
-    pub async fn transfer_in_place<W: Word>(&mut self, data: &mut [W]) -> Result<(), Error> {
-        self._peri.transfer_in_place(data).await
+    /// Write data directly to the raw I2S ringbuffer.
+    /// This can be used to fill the buffer before starting the DMA transfer.
+    pub async fn write_immediate(&mut self, data: &mut [W]) -> Result<(usize, usize), Error> {
+        match &mut self.tx_ring_buffer {
+            Some(ring) => Ok(ring.write_immediate(data)?),
+            _ => return Err(Error::NotATransmitter),
+        }
     }
 
     fn new_inner<T: Instance>(
@@ -283,23 +471,23 @@ impl<'d> I2S<'d> {
         rxsd: Option<PeripheralRef<'d, AnyPin>>,
         ws: impl Peripheral<P = impl WsPin<T>> + 'd,
         ck: impl Peripheral<P = impl CkPin<T>> + 'd,
-        mck: impl Peripheral<P = impl MckPin<T>> + 'd,
-        txdma: Option<ChannelAndRequest<'d>>,
-        rxdma: Option<ChannelAndRequest<'d>>,
+        mck: Option<PeripheralRef<'d, AnyPin>>,
+        txdma: Option<(ChannelAndRequest<'d>, &'d mut [W])>,
+        rxdma: Option<(ChannelAndRequest<'d>, &'d mut [W])>,
         freq: Hertz,
         config: Config,
         function: Function,
     ) -> Self {
-        into_ref!(ws, ck, mck);
+        into_ref!(ws, ck);
 
         ws.set_as_af(ws.af_num(), AfType::output(OutputType::PushPull, Speed::VeryHigh));
         ck.set_as_af(ck.af_num(), AfType::output(OutputType::PushPull, Speed::VeryHigh));
-        mck.set_as_af(mck.af_num(), AfType::output(OutputType::PushPull, Speed::VeryHigh));
 
-        let mut spi_cfg = SpiConfig::default();
-        spi_cfg.frequency = freq;
-
-        let spi = Spi::new_internal(peri, txdma, rxdma, spi_cfg);
+        let spi = Spi::new_internal(peri, None, None, {
+            let mut config = SpiConfig::default();
+            config.frequency = freq;
+            config
+        });
 
         let regs = T::info().regs;
 
@@ -390,22 +578,29 @@ impl<'d> I2S<'d> {
                 w.set_i2se(true);
             });
 
-            #[cfg(spi_v3)]
-            regs.cr1().modify(|w| w.set_spe(true));
-        }
-
-        Self {
-            _peri: spi,
-            txsd: txsd.map(|w| w.map_into()),
-            rxsd: rxsd.map(|w| w.map_into()),
-            ws: Some(ws.map_into()),
-            ck: Some(ck.map_into()),
-            mck: Some(mck.map_into()),
+            let mut opts = TransferOptions::default();
+            opts.half_transfer_ir = true;
+
+            Self {
+                mode: config.mode,
+                spi,
+                txsd: txsd.map(|w| w.map_into()),
+                rxsd: rxsd.map(|w| w.map_into()),
+                ws: Some(ws.map_into()),
+                ck: Some(ck.map_into()),
+                mck: mck.map(|w| w.map_into()),
+                tx_ring_buffer: txdma.map(|(ch, buf)| unsafe {
+                    WritableRingBuffer::new(ch.channel, ch.request, regs.tx_ptr(), buf, opts)
+                }),
+                rx_ring_buffer: rxdma.map(|(ch, buf)| unsafe {
+                    ReadableRingBuffer::new(ch.channel, ch.request, regs.rx_ptr(), buf, opts)
+                }),
+            }
         }
     }
 }
 
-impl<'d> Drop for I2S<'d> {
+impl<'d, W: Word> Drop for I2S<'d, W> {
     fn drop(&mut self) {
         self.txsd.as_ref().map(|x| x.set_as_disconnected());
         self.rxsd.as_ref().map(|x| x.set_as_disconnected());
diff --git a/embassy-stm32/src/spi/mod.rs b/embassy-stm32/src/spi/mod.rs
index d034c028e..a65b0cc64 100644
--- a/embassy-stm32/src/spi/mod.rs
+++ b/embassy-stm32/src/spi/mod.rs
@@ -311,8 +311,7 @@ impl<'d, M: PeriMode> Spi<'d, M> {
         }
     }
 
-    /// Set SPI word size. Disables SPI if needed, you have to enable it back yourself.
-    fn set_word_size(&mut self, word_size: word_impl::Config) {
+    pub(crate) fn set_word_size(&mut self, word_size: word_impl::Config) {
         if self.current_word_size == word_size {
             return;
         }
@@ -895,7 +894,7 @@ fn compute_frequency(kernel_clock: Hertz, br: Br) -> Hertz {
     kernel_clock / div
 }
 
-trait RegsExt {
+pub(crate) trait RegsExt {
     fn tx_ptr<W>(&self) -> *mut W;
     fn rx_ptr<W>(&self) -> *mut W;
 }
@@ -983,7 +982,7 @@ fn spin_until_rx_ready(regs: Regs) -> Result<(), Error> {
     }
 }
 
-fn flush_rx_fifo(regs: Regs) {
+pub(crate) fn flush_rx_fifo(regs: Regs) {
     #[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
     while regs.sr().read().rxne() {
         #[cfg(not(spi_v2))]
@@ -997,7 +996,7 @@ fn flush_rx_fifo(regs: Regs) {
     }
 }
 
-fn set_txdmaen(regs: Regs, val: bool) {
+pub(crate) fn set_txdmaen(regs: Regs, val: bool) {
     #[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
     regs.cr2().modify(|reg| {
         reg.set_txdmaen(val);
@@ -1008,7 +1007,7 @@ fn set_txdmaen(regs: Regs, val: bool) {
     });
 }
 
-fn set_rxdmaen(regs: Regs, val: bool) {
+pub(crate) fn set_rxdmaen(regs: Regs, val: bool) {
     #[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
     regs.cr2().modify(|reg| {
         reg.set_rxdmaen(val);
@@ -1169,7 +1168,7 @@ impl<'d, W: Word> embedded_hal_async::spi::SpiBus<W> for Spi<'d, Async> {
     }
 }
 
-trait SealedWord {
+pub(crate) trait SealedWord {
     const CONFIG: word_impl::Config;
 }
 
diff --git a/examples/stm32f4/src/bin/i2s_dma.rs b/examples/stm32f4/src/bin/i2s_dma.rs
index 27b165f1b..68392847b 100644
--- a/examples/stm32f4/src/bin/i2s_dma.rs
+++ b/examples/stm32f4/src/bin/i2s_dma.rs
@@ -1,13 +1,10 @@
 #![no_std]
 #![no_main]
 
-use core::fmt::Write;
-
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_stm32::i2s::{Config, I2S};
 use embassy_stm32::time::Hertz;
-use heapless::String;
 use {defmt_rtt as _, panic_probe as _};
 
 #[embassy_executor::main]
@@ -15,6 +12,8 @@ async fn main(_spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
     info!("Hello World!");
 
+    let mut dma_buffer = [0x00_u16; 128];
+
     let mut i2s = I2S::new_txonly(
         p.SPI2,
         p.PC3,  // sd
@@ -22,13 +21,13 @@ async fn main(_spawner: Spawner) {
         p.PB10, // ck
         p.PC6,  // mck
         p.DMA1_CH4,
+        &mut dma_buffer,
         Hertz(1_000_000),
         Config::default(),
     );
 
-    for n in 0u32.. {
-        let mut write: String<128> = String::new();
-        core::write!(&mut write, "Hello DMA World {}!\r\n", n).unwrap();
-        i2s.write(&mut write.as_bytes()).await.ok();
+    for i in 0_u16.. {
+        i2s.write(&mut [i * 2; 64]).await.ok();
+        i2s.write(&mut [i * 2 + 1; 64]).await.ok();
     }
 }