stm32/dma: add double buffered mode for DMA, update DCMI.

2 files changed, 182 insertions, 14 deletions

diff --git a/embassy-stm32/src/dcmi.rs b/embassy-stm32/src/dcmi.rs
index 0b34553cf..c19be86c6 100644
--- a/embassy-stm32/src/dcmi.rs
+++ b/embassy-stm32/src/dcmi.rs
@@ -434,9 +434,13 @@ where
         result
     }
 
+    #[cfg(not(dma))]
     async fn capture_giant(&mut self, _buffer: &mut [u32]) -> Result<(), Error> {
-        todo!()
-        /*
+        panic!("capturing to buffers larger than 0xffff is only supported on DMA for now, not on BDMA or GPDMA.");
+    }
+
+    #[cfg(dma)]
+    async fn capture_giant(&mut self, buffer: &mut [u32]) -> Result<(), Error> {
         use crate::dma::TransferOptions;
 
         let data_len = buffer.len();
@@ -460,16 +464,24 @@ where
         let r = self.inner.regs();
         let src = r.dr().ptr() as *mut u32;
 
-        unsafe {
-            channel.start_double_buffered_read(request, src, m0ar, m1ar, chunk_size, TransferOptions::default());
-        }
+        let mut transfer = unsafe {
+            crate::dma::DoubleBuffered::new_read(
+                &mut self.dma,
+                request,
+                src,
+                m0ar,
+                m1ar,
+                chunk_size,
+                TransferOptions::default(),
+            )
+        };
 
         let mut last_chunk_set_for_transfer = false;
         let mut buffer0_last_accessible = false;
         let dma_result = poll_fn(|cx| {
-            channel.set_waker(cx.waker());
+            transfer.set_waker(cx.waker());
 
-            let buffer0_currently_accessible = unsafe { channel.is_buffer0_accessible() };
+            let buffer0_currently_accessible = transfer.is_buffer0_accessible();
 
             // check if the accessible buffer changed since last poll
             if buffer0_last_accessible == buffer0_currently_accessible {
@@ -480,21 +492,21 @@ where
             if remaining_chunks != 0 {
                 if remaining_chunks % 2 == 0 && buffer0_currently_accessible {
                     m0ar = unsafe { m0ar.add(2 * chunk_size) };
-                    unsafe { channel.set_buffer0(m0ar) }
+                    unsafe { transfer.set_buffer0(m0ar) }
                     remaining_chunks -= 1;
                 } else if !buffer0_currently_accessible {
                     m1ar = unsafe { m1ar.add(2 * chunk_size) };
-                    unsafe { channel.set_buffer1(m1ar) };
+                    unsafe { transfer.set_buffer1(m1ar) };
                     remaining_chunks -= 1;
                 }
             } else {
                 if buffer0_currently_accessible {
-                    unsafe { channel.set_buffer0(buffer.as_mut_ptr()) }
+                    unsafe { transfer.set_buffer0(buffer.as_mut_ptr()) }
                 } else {
-                    unsafe { channel.set_buffer1(buffer.as_mut_ptr()) }
+                    unsafe { transfer.set_buffer1(buffer.as_mut_ptr()) }
                 }
                 if last_chunk_set_for_transfer {
-                    channel.request_stop();
+                    transfer.request_stop();
                     return Poll::Ready(());
                 }
                 last_chunk_set_for_transfer = true;
@@ -542,7 +554,6 @@ where
         unsafe { Self::toggle(false) };
 
         result
-        */
     }
 }
 
diff --git a/embassy-stm32/src/dma/dma.rs b/embassy-stm32/src/dma/dma.rs
index 9052aa110..62c092241 100644
--- a/embassy-stm32/src/dma/dma.rs
+++ b/embassy-stm32/src/dma/dma.rs
@@ -1,7 +1,8 @@
 use core::future::Future;
+use core::marker::PhantomData;
 use core::pin::Pin;
 use core::sync::atomic::{fence, Ordering};
-use core::task::{Context, Poll};
+use core::task::{Context, Poll, Waker};
 
 use embassy_cortex_m::interrupt::Priority;
 use embassy_hal_common::{into_ref, Peripheral, PeripheralRef};
@@ -440,3 +441,159 @@ impl<'a, C: Channel> Future for Transfer<'a, C> {
         }
     }
 }
+
+// ==================================
+
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct DoubleBuffered<'a, C: Channel, W: Word> {
+    channel: PeripheralRef<'a, C>,
+    _phantom: PhantomData<W>,
+}
+
+impl<'a, C: Channel, W: Word> DoubleBuffered<'a, C, W> {
+    pub unsafe fn new_read(
+        channel: impl Peripheral<P = C> + 'a,
+        _request: Request,
+        peri_addr: *mut W,
+        buf0: *mut W,
+        buf1: *mut W,
+        len: usize,
+        options: TransferOptions,
+    ) -> Self {
+        into_ref!(channel);
+        assert!(len > 0 && len <= 0xFFFF);
+
+        let dir = Dir::PeripheralToMemory;
+        let data_size = W::bits();
+
+        let channel_number = channel.num();
+        let dma = channel.regs();
+
+        // "Preceding reads and writes cannot be moved past subsequent writes."
+        fence(Ordering::SeqCst);
+
+        let mut this = Self {
+            channel,
+            _phantom: PhantomData,
+        };
+        this.clear_irqs();
+
+        #[cfg(dmamux)]
+        super::dmamux::configure_dmamux(&mut *this.channel, _request);
+
+        let ch = dma.st(channel_number);
+        ch.par().write_value(peri_addr as u32);
+        ch.m0ar().write_value(buf0 as u32);
+        ch.m1ar().write_value(buf1 as u32);
+        ch.ndtr().write_value(regs::Ndtr(len as _));
+        ch.fcr().write(|w| {
+            if let Some(fth) = options.fifo_threshold {
+                // FIFO mode
+                w.set_dmdis(vals::Dmdis::DISABLED);
+                w.set_fth(fth.into());
+            } else {
+                // Direct mode
+                w.set_dmdis(vals::Dmdis::ENABLED);
+            }
+        });
+        ch.cr().write(|w| {
+            w.set_dir(dir.into());
+            w.set_msize(data_size.into());
+            w.set_psize(data_size.into());
+            w.set_pl(vals::Pl::VERYHIGH);
+            w.set_minc(vals::Inc::INCREMENTED);
+            w.set_pinc(vals::Inc::FIXED);
+            w.set_teie(true);
+            w.set_tcie(true);
+            #[cfg(dma_v1)]
+            w.set_trbuff(true);
+
+            #[cfg(dma_v2)]
+            w.set_chsel(_request);
+
+            w.set_pburst(options.pburst.into());
+            w.set_mburst(options.mburst.into());
+            w.set_pfctrl(options.flow_ctrl.into());
+
+            w.set_en(true);
+        });
+
+        this
+    }
+
+    fn clear_irqs(&mut self) {
+        let channel_number = self.channel.num();
+        let dma = self.channel.regs();
+        let isrn = channel_number / 4;
+        let isrbit = channel_number % 4;
+
+        unsafe {
+            dma.ifcr(isrn).write(|w| {
+                w.set_tcif(isrbit, true);
+                w.set_teif(isrbit, true);
+            })
+        }
+    }
+
+    pub unsafe fn set_buffer0(&mut self, buffer: *mut W) {
+        let ch = self.channel.regs().st(self.channel.num());
+        ch.m0ar().write_value(buffer as _);
+    }
+
+    pub unsafe fn set_buffer1(&mut self, buffer: *mut W) {
+        let ch = self.channel.regs().st(self.channel.num());
+        ch.m1ar().write_value(buffer as _);
+    }
+
+    pub fn is_buffer0_accessible(&mut self) -> bool {
+        let ch = self.channel.regs().st(self.channel.num());
+        unsafe { ch.cr().read() }.ct() == vals::Ct::MEMORY1
+    }
+
+    pub fn set_waker(&mut self, waker: &Waker) {
+        STATE.ch_wakers[self.channel.index()].register(waker);
+    }
+
+    pub fn request_stop(&mut self) {
+        let ch = self.channel.regs().st(self.channel.num());
+
+        // Disable the channel. Keep the IEs enabled so the irqs still fire.
+        unsafe {
+            ch.cr().write(|w| {
+                w.set_teie(true);
+                w.set_tcie(true);
+            })
+        }
+    }
+
+    pub fn is_running(&mut self) -> bool {
+        let ch = self.channel.regs().st(self.channel.num());
+        unsafe { ch.cr().read() }.en()
+    }
+
+    /// Gets the total remaining transfers for the channel
+    /// Note: this will be zero for transfers that completed without cancellation.
+    pub fn get_remaining_transfers(&self) -> u16 {
+        let ch = self.channel.regs().st(self.channel.num());
+        unsafe { ch.ndtr().read() }.ndt()
+    }
+
+    pub fn blocking_wait(mut self) {
+        while self.is_running() {}
+
+        // "Subsequent reads and writes cannot be moved ahead of preceding reads."
+        fence(Ordering::SeqCst);
+
+        core::mem::forget(self);
+    }
+}
+
+impl<'a, C: Channel, W: Word> Drop for DoubleBuffered<'a, C, W> {
+    fn drop(&mut self) {
+        self.request_stop();
+        while self.is_running() {}
+
+        // "Subsequent reads and writes cannot be moved ahead of preceding reads."
+        fence(Ordering::SeqCst);
+    }
+}