Preliminary DMA support for RP2040

embassy-rp/src/dma.rs

@@ -1,39 +1,71 @@
+use core::pin::Pin;
 use core::sync::atomic::{compiler_fence, Ordering};
+use core::task::{Context, Poll};
 
-use embassy_hal_common::impl_peripheral;
+use embassy_hal_common::{impl_peripheral, into_ref, Peripheral, PeripheralRef};
+use futures::Future;
 
 use crate::pac::dma::vals;
 use crate::{pac, peripherals};
 
-pub struct Dma<T: Channel> {
-    _inner: T,
+pub fn copy<'a, C: Channel, W: Word>(ch: impl Peripheral<P = C> + 'a, from: &[W], to: &mut [W]) -> Transfer<'a, C> {
+    assert!(from.len() == to.len());
+
+    into_ref!(ch);
+
+    unsafe {
+        let p = ch.regs();
+
+        p.read_addr().write_value(from.as_ptr() as u32);
+        p.write_addr().write_value(to.as_mut_ptr() as u32);
+        p.trans_count().write_value(from.len() as u32);
+
+        compiler_fence(Ordering::SeqCst);
+
+        p.ctrl_trig().write(|w| {
+            w.set_data_size(W::size());
+            w.set_incr_read(true);
+            w.set_incr_write(true);
+            w.set_chain_to(ch.number());
+            w.set_en(true);
+        });
+
+        // FIXME:
+        while p.ctrl_trig().read().busy() {}
+
+        compiler_fence(Ordering::SeqCst);
+    }
+    Transfer::new(ch)
 }
 
-impl<T: Channel> Dma<T> {
-    pub fn copy(inner: T, from: &[u32], to: &mut [u32]) {
-        assert!(from.len() == to.len());
+pub(crate) struct Transfer<'a, C: Channel> {
+    channel: PeripheralRef<'a, C>,
+}
 
-        unsafe {
-            let p = inner.regs();
+impl<'a, C: Channel> Transfer<'a, C> {
+    pub(crate) fn new(channel: impl Peripheral<P = C> + 'a) -> Self {
+        into_ref!(channel);
+        Self { channel }
+    }
+}
 
-            p.read_addr().write_value(from.as_ptr() as u32);
-            p.write_addr().write_value(to.as_mut_ptr() as u32);
-            p.trans_count().write_value(from.len() as u32);
+impl<'a, C: Channel> Drop for Transfer<'a, C> {
+    fn drop(&mut self) {
+        // self.channel.request_stop();
+        // while self.channel.is_running() {}
+    }
+}
 
-            compiler_fence(Ordering::SeqCst);
-
-            p.ctrl_trig().write(|w| {
-                w.set_data_size(vals::DataSize::SIZE_WORD);
-                w.set_incr_read(true);
-                w.set_incr_write(true);
-                w.set_chain_to(inner.number());
-                w.set_en(true);
-            });
-
-            while p.ctrl_trig().read().busy() {}
-
-            compiler_fence(Ordering::SeqCst);
-        }
+impl<'a, C: Channel> Unpin for Transfer<'a, C> {}
+impl<'a, C: Channel> Future for Transfer<'a, C> {
+    type Output = ();
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        // self.channel.set_waker(cx.waker());
+        // if self.channel.is_running() {
+        //     Poll::Pending
+        // } else {
+            Poll::Ready(())
+        // }
     }
 }
 
@@ -42,38 +74,77 @@ pub struct NoDma;
 impl_peripheral!(NoDma);
 
 mod sealed {
-    use super::*;
+    pub trait Channel {}
 
-    pub trait Channel {
-        fn number(&self) -> u8;
+    pub trait Word {}
+}
 
-        fn regs(&self) -> pac::dma::Channel {
-            pac::DMA.ch(self.number() as _)
+pub trait Channel: Peripheral<P = Self> + sealed::Channel + Into<AnyChannel> + Sized + 'static {
+    fn number(&self) -> u8;
+
+    fn regs(&self) -> pac::dma::Channel {
+        pac::DMA.ch(self.number() as _)
+    }
+
+    fn degrade(self) -> AnyChannel {
+        AnyChannel {
+            number: self.number(),
         }
     }
 }
 
-pub trait Channel: sealed::Channel {}
+pub trait Word: sealed::Word {
+    fn size() -> vals::DataSize;
+}
+
+impl sealed::Word for u8 {}
+impl Word for u8 {
+    fn size() -> vals::DataSize {
+        vals::DataSize::SIZE_BYTE
+    }
+}
+
+impl sealed::Word for u16 {}
+impl Word for u16 {
+    fn size() -> vals::DataSize {
+        vals::DataSize::SIZE_HALFWORD
+    }
+}
+
+impl sealed::Word for u32 {}
+impl Word for u32 {
+    fn size() -> vals::DataSize {
+        vals::DataSize::SIZE_WORD
+    }
+}
 
 pub struct AnyChannel {
     number: u8,
 }
 
-impl Channel for AnyChannel {}
-impl sealed::Channel for AnyChannel {
+impl_peripheral!(AnyChannel);
+
+impl sealed::Channel for AnyChannel {}
+impl Channel for AnyChannel {
     fn number(&self) -> u8 {
         self.number
     }
 }
 
 macro_rules! channel {
-    ($type:ident, $num:expr) => {
-        impl Channel for peripherals::$type {}
-        impl sealed::Channel for peripherals::$type {
+    ($name:ident, $num:expr) => {
+        impl sealed::Channel for peripherals::$name {}
+        impl Channel for peripherals::$name {
             fn number(&self) -> u8 {
                 $num
             }
         }
+
+        impl From<peripherals::$name> for crate::dma::AnyChannel {
+            fn from(val: peripherals::$name) -> Self {
+                crate::dma::Channel::degrade(val)
+            }
+        }
     };
 }