feat: add SPDIFRX driver

3 files changed, 350 insertions, 0 deletions

diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index 71bfb3747..348d48b9b 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -1220,6 +1220,17 @@ fn main() {
                     impl_dac_pin!( #peri, #pin_name, #ch);
                     })
                 }
+
+                if regs.kind == "spdifrx" {
+                    let peri = format_ident!("{}", p.name);
+                    let pin_name = format_ident!("{}", pin.pin);
+                    let af = pin.af.unwrap_or(0);
+                    let sel: u8 = pin.signal.strip_prefix("IN").unwrap().parse().unwrap();
+
+                    g.extend(quote! {
+                    impl_spdifrx_pin!( #peri, #pin_name, #af, #sel);
+                    })
+                }
             }
         }
     }
@@ -1244,6 +1255,7 @@ fn main() {
         (("sai", "B"), quote!(crate::sai::Dma<B>)),
         (("spi", "RX"), quote!(crate::spi::RxDma)),
         (("spi", "TX"), quote!(crate::spi::TxDma)),
+        (("spdifrx", "RX"), quote!(crate::spdifrx::Dma)),
         (("i2c", "RX"), quote!(crate::i2c::RxDma)),
         (("i2c", "TX"), quote!(crate::i2c::TxDma)),
         (("dcmi", "DCMI"), quote!(crate::dcmi::FrameDma)),
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 286a18da2..e189351d1 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -107,6 +107,8 @@ pub mod rtc;
 pub mod sai;
 #[cfg(sdmmc)]
 pub mod sdmmc;
+#[cfg(spdifrx)]
+pub mod spdifrx;
 #[cfg(spi)]
 pub mod spi;
 #[cfg(tsc)]
diff --git a/embassy-stm32/src/spdifrx/mod.rs b/embassy-stm32/src/spdifrx/mod.rs
new file mode 100644
index 000000000..bfc8bff29
--- /dev/null
+++ b/embassy-stm32/src/spdifrx/mod.rs
@@ -0,0 +1,336 @@
+//! S/PDIF receiver
+#![macro_use]
+#![cfg_attr(gpdma, allow(unused))]
+
+use core::marker::PhantomData;
+
+use embassy_hal_internal::{into_ref, PeripheralRef};
+use embassy_sync::waitqueue::AtomicWaker;
+
+use crate::dma::ringbuffer::Error as RingbufferError;
+pub use crate::dma::word;
+#[cfg(not(gpdma))]
+use crate::dma::ReadableRingBuffer;
+use crate::dma::{Channel, TransferOptions};
+use crate::gpio::{AfType, AnyPin, Pull, SealedPin as _};
+use crate::interrupt::typelevel::Interrupt;
+use crate::pac::spdifrx::Spdifrx as Regs;
+use crate::rcc::{RccInfo, SealedRccPeripheral};
+use crate::{interrupt, peripherals, Peripheral};
+
+/// Possible S/PDIF preamble types.
+#[allow(dead_code)]
+#[repr(u8)]
+enum PreambleType {
+    Unused = 0x00,
+    /// The preamble changes to preamble “B” once every 192 frames to identify the start of the block structure used to
+    /// organize the channel status and user information.
+    B = 0x01,
+    /// The first sub-frame (left or “A” channel in stereophonic operation and primary channel in monophonic operation)
+    /// normally starts with preamble “M”
+    M = 0x02,
+    /// The second sub-frame (right or “B” channel in stereophonic operation and secondary channel in monophonic
+    /// operation) always starts with preamble “W”.
+    W = 0x03,
+}
+
+macro_rules! new_spdifrx_pin {
+    ($name:ident, $af_type:expr) => {{
+        let pin = $name.into_ref();
+        let input_sel = pin.input_sel();
+        pin.set_as_af(pin.af_num(), $af_type);
+        (Some(pin.map_into()), input_sel)
+    }};
+}
+
+macro_rules! impl_spdifrx_pin {
+    ($inst:ident, $pin:ident, $af:expr, $sel:expr) => {
+        impl crate::spdifrx::InPin<peripherals::$inst> for crate::peripherals::$pin {
+            fn af_num(&self) -> u8 {
+                $af
+            }
+            fn input_sel(&self) -> u8 {
+                $sel
+            }
+        }
+    };
+}
+
+/// Ring-buffered SPDIFRX driver.
+///
+/// Data is read by DMAs and stored in a ring buffer.
+#[cfg(not(gpdma))]
+pub struct Spdifrx<'d, T: Instance> {
+    _peri: PeripheralRef<'d, T>,
+    spdifrx_in: Option<PeripheralRef<'d, AnyPin>>,
+    data_ring_buffer: ReadableRingBuffer<'d, u32>,
+}
+
+/// Gives the address of the data register.
+fn dr_address(r: Regs) -> *mut u32 {
+    #[cfg(spdifrx_v1)]
+    let address = r.dr().as_ptr() as _;
+    #[cfg(spdifrx_h7)]
+    let address = r.fmt0_dr().as_ptr() as _; // All fmtx_dr() implementations have the same address.
+
+    return address;
+}
+
+/// Gives the address of the channel status register.
+#[allow(unused)]
+fn csr_address(r: Regs) -> *mut u32 {
+    r.csr().as_ptr() as _
+}
+
+/// Select the channel for capturing control information.
+pub enum ControlChannelSelection {
+    /// Capture control info from channel A.
+    A,
+    /// Capture control info from channel B.
+    B,
+}
+
+/// Configuration options for the SPDIFRX driver.
+pub struct Config {
+    /// Select the channel for capturing control information.
+    pub control_channel_selection: ControlChannelSelection,
+}
+
+/// S/PDIF errors.
+#[derive(Debug)]
+pub enum Error {
+    /// DMA overrun error.
+    RingbufferError(RingbufferError),
+    /// Left/right channel synchronization error.
+    ChannelSyncError,
+}
+
+impl From<RingbufferError> for Error {
+    fn from(error: RingbufferError) -> Self {
+        Self::RingbufferError(error)
+    }
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            control_channel_selection: ControlChannelSelection::A,
+        }
+    }
+}
+
+#[cfg(not(gpdma))]
+impl<'d, T: Instance> Spdifrx<'d, T> {
+    fn dma_opts() -> TransferOptions {
+        TransferOptions {
+            half_transfer_ir: true,
+            // new_write() and new_read() always use circular mode
+            ..Default::default()
+        }
+    }
+
+    /// Create a new `Spdifrx` instance.
+    pub fn new(
+        peri: impl Peripheral<P = T> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::GlobalInterrupt, GlobalInterruptHandler<T>> + 'd,
+        config: Config,
+        spdifrx_in: impl Peripheral<P = impl InPin<T>> + 'd,
+        data_dma: impl Peripheral<P = impl Channel + Dma<T>> + 'd,
+        data_dma_buf: &'d mut [u32],
+    ) -> Self {
+        let (spdifrx_in, input_sel) = new_spdifrx_pin!(spdifrx_in, AfType::input(Pull::None));
+        Self::setup(config, input_sel);
+
+        into_ref!(peri, data_dma);
+
+        let regs = T::info().regs;
+        let dr_request = data_dma.request();
+        let dr_ring_buffer =
+            unsafe { ReadableRingBuffer::new(data_dma, dr_request, dr_address(regs), data_dma_buf, Self::dma_opts()) };
+
+        Self {
+            _peri: peri,
+            spdifrx_in,
+            data_ring_buffer: dr_ring_buffer,
+        }
+    }
+
+    fn setup(config: Config, input_sel: u8) {
+        T::info().rcc.enable_and_reset();
+        T::GlobalInterrupt::unpend();
+        unsafe { T::GlobalInterrupt::enable() };
+
+        let regs = T::info().regs;
+
+        regs.imr().write(|imr| {
+            imr.set_ifeie(true); // Enables interrupts for TERR, SERR, FERR.
+            imr.set_syncdie(true); // Enables SYNCD interrupt.
+        });
+
+        regs.cr().write(|cr| {
+            cr.set_spdifen(0x00); // Disable SPDIF receiver synchronization.
+            cr.set_rxdmaen(true); // Use RX DMA for data. Enabled on `read`.
+            cr.set_cbdmaen(false); // Do not capture channel info.
+            cr.set_rxsteo(true); // Operate in stereo mode.
+            cr.set_drfmt(0x01); // Data is left-aligned (MSB).
+
+            // Disable all status fields in the data register.
+            // Status can be obtained directly with the status register DMA.
+            cr.set_pmsk(false); // Write parity bit to the data register. FIXME: Add parity check.
+            cr.set_vmsk(false); // Write validity to the data register.
+            cr.set_cumsk(true); // Do not write C and U bits to the data register.
+            cr.set_ptmsk(false); // Write preamble bits to the data register.
+
+            cr.set_chsel(match config.control_channel_selection {
+                ControlChannelSelection::A => false,
+                ControlChannelSelection::B => true,
+            }); // Select channel status source.
+
+            cr.set_nbtr(0x02); // 16 attempts are allowed.
+            cr.set_wfa(true); // Wait for activity before going to synchronization phase.
+            cr.set_insel(input_sel); // Input pin selection.
+
+            #[cfg(stm32h7)]
+            cr.set_cksen(true); // Generate a symbol clock.
+
+            #[cfg(stm32h7)]
+            cr.set_cksbkpen(false); // Do not generate a backup symbol clock.
+        });
+    }
+
+    /// Start the SPDIFRX driver.
+    pub fn start(&mut self) {
+        self.data_ring_buffer.start();
+
+        T::info().regs.cr().modify(|cr| {
+            cr.set_spdifen(0x03); // Enable S/PDIF receiver.
+        });
+    }
+
+    /// Read from the SPDIFRX data ring buffer.
+    ///
+    /// SPDIFRX 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 [u32]) -> Result<(), Error> {
+        self.data_ring_buffer.read_exact(data).await?;
+
+        let first_preamble = (data[0] >> 4) & 0b11_u32;
+        if (first_preamble as u8) == (PreambleType::W as u8) {
+            trace!("S/PDIF left/right mismatch");
+
+            // Resynchronize until the first sample is for the left channel.
+            self.data_ring_buffer.clear();
+            return Err(Error::ChannelSyncError);
+        };
+
+        for sample in data.as_mut() {
+            if (*sample & (0x0002_u32)) == 0x0001 {
+                // Discard invalid samples, setting them to mute level.
+                *sample = 0;
+            } else {
+                // Discard status information in the lowest byte.
+                *sample &= 0xFFFFFF00;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(not(gpdma))]
+impl<'d, T: Instance> Drop for Spdifrx<'d, T> {
+    fn drop(&mut self) {
+        T::info().regs.cr().modify(|cr| cr.set_spdifen(0x00));
+        self.spdifrx_in.as_ref().map(|x| x.set_as_disconnected());
+    }
+}
+
+struct State {
+    #[allow(unused)]
+    waker: AtomicWaker,
+}
+
+impl State {
+    const fn new() -> Self {
+        Self {
+            waker: AtomicWaker::new(),
+        }
+    }
+}
+
+struct Info {
+    regs: crate::pac::spdifrx::Spdifrx,
+    rcc: RccInfo,
+}
+
+peri_trait!(
+    irqs: [GlobalInterrupt],
+);
+
+/// SPIDFRX pin trait
+pub trait InPin<T: Instance>: crate::gpio::Pin {
+    /// Get the GPIO AF number needed to use this pin.
+    fn af_num(&self) -> u8;
+    /// Get the SPIDFRX INSEL number needed to use this pin.
+    fn input_sel(&self) -> u8;
+}
+
+dma_trait!(Dma, Instance);
+
+/// Global interrupt handler.
+pub struct GlobalInterruptHandler<T: Instance> {
+    _phantom: PhantomData<T>,
+}
+
+impl<T: Instance> interrupt::typelevel::Handler<T::GlobalInterrupt> for GlobalInterruptHandler<T> {
+    unsafe fn on_interrupt() {
+        T::state().waker.wake();
+
+        let regs = T::info().regs;
+        let sr = regs.sr().read();
+
+        if sr.serr() || sr.terr() || sr.ferr() {
+            trace!("SPDIFRX error, resync");
+
+            // Clear errors by disabling SPDIFRX, then reenable.
+            regs.cr().modify(|cr| cr.set_spdifen(0x00));
+            regs.cr().modify(|cr| cr.set_spdifen(0x03));
+        } else if sr.syncd() {
+            // Synchronization was successful.
+            trace!("SPDIFRX sync success");
+        }
+
+        // Clear interrupt flags.
+        regs.ifcr().write(|ifcr| {
+            ifcr.set_perrcf(true); // Clears parity error flag.
+            ifcr.set_ovrcf(true); // Clears overrun error flag.
+            ifcr.set_sbdcf(true); // Clears synchronization block detected flag.
+            ifcr.set_syncdcf(true); // Clears SYNCD from SR (was read above).
+        });
+    }
+}
+
+foreach_peripheral!(
+    (spdifrx, $inst:ident) => {
+        #[allow(private_interfaces)]
+        impl SealedInstance for peripherals::$inst {
+            fn info() -> &'static Info {
+                static INFO: Info = Info{
+                    regs: crate::pac::$inst,
+                    rcc: crate::peripherals::$inst::RCC_INFO,
+                };
+                &INFO
+            }
+            fn state() -> &'static State {
+                static STATE: State = State::new();
+                &STATE
+            }
+        }
+
+        impl Instance for peripherals::$inst {
+            type GlobalInterrupt = crate::_generated::peripheral_interrupts::$inst::GLOBAL;
+        }
+    };
+);