From 043f0ea5088e02f509b3e1f013192c44c7854540 Mon Sep 17 00:00:00 2001
From: Bob McWhirter <bmcwhirt@redhat.com>
Date: Fri, 2 Jul 2021 09:54:31 -0400
Subject: [PATCH] Checkpoint DMAMUX channel setup.

---
 embassy-stm32/src/dmamux/mod.rs   | 187 ++++++++++++++++++++++++++++++
 embassy-stm32/src/lib.rs          |   2 +
 embassy-stm32/src/usart/v3.rs     |   2 +-
 examples/stm32l4/src/bin/usart.rs |   4 -
 4 files changed, 190 insertions(+), 5 deletions(-)
 create mode 100644 embassy-stm32/src/dmamux/mod.rs

diff --git a/embassy-stm32/src/dmamux/mod.rs b/embassy-stm32/src/dmamux/mod.rs
new file mode 100644
index 00000000..4939d26a
--- /dev/null
+++ b/embassy-stm32/src/dmamux/mod.rs
@@ -0,0 +1,187 @@
+#![macro_use]
+
+use crate::pac::dma_channels;
+use crate::pac::dma_requests;
+use crate::pac::peripherals;
+use crate::peripherals;
+
+use core::future::Future;
+
+use crate::dma::{ReadDma, WriteDma};
+
+#[allow(unused)]
+pub(crate) async unsafe fn transfer_p2m(
+    ch: &mut impl Channel,
+    ch_func: u8,
+    src: *const u8,
+    dst: &mut [u8],
+) {
+    unimplemented!()
+}
+
+#[allow(unused)]
+pub(crate) async unsafe fn transfer_m2p(
+    ch: &mut impl Channel,
+    ch_func: u8,
+    src: &[u8],
+    dst: *mut u8,
+) {
+    unimplemented!()
+}
+
+pub(crate) mod sealed {
+    use super::*;
+
+    pub trait DmaMux {}
+
+    pub trait Channel {
+        fn dmamux_ch_num(&self) -> u8;
+    }
+
+    pub trait PeripheralChannel<PERI, OP>: Channel {
+        fn request(&self) -> u8;
+    }
+}
+
+pub trait DmaMux: sealed::DmaMux {}
+pub trait Channel: sealed::Channel {}
+pub trait PeripheralChannel<PERI, OP>: sealed::Channel {}
+
+pub struct P2M;
+pub struct M2P;
+
+macro_rules! impl_dma_channel {
+    ($channel_peri:ident, $dmamux_peri:ident, $channel_num:expr, $dma_num:expr) => {
+        impl Channel for peripherals::$channel_peri {}
+        impl sealed::Channel for peripherals::$channel_peri {
+            fn dmamux_ch_num(&self) -> u8 {
+                ($dma_num * 8) + $channel_num
+            }
+        }
+
+        impl<T> WriteDma<T> for peripherals::$channel_peri
+        where
+            Self: sealed::PeripheralChannel<T, M2P>,
+            T: 'static,
+        {
+            type WriteDmaFuture<'a> = impl Future<Output = ()>;
+
+            fn transfer<'a>(&'a mut self, buf: &'a [u8], dst: *mut u8) -> Self::WriteDmaFuture<'a>
+            where
+                T: 'a,
+            {
+                let request = sealed::PeripheralChannel::<T, M2P>::request(self);
+                unsafe { transfer_m2p(self, request, buf, dst) }
+            }
+        }
+
+        impl<T> ReadDma<T> for peripherals::$channel_peri
+        where
+            Self: sealed::PeripheralChannel<T, P2M>,
+            T: 'static,
+        {
+            type ReadDmaFuture<'a> = impl Future<Output = ()>;
+
+            fn transfer<'a>(
+                &'a mut self,
+                src: *const u8,
+                buf: &'a mut [u8],
+            ) -> Self::ReadDmaFuture<'a>
+            where
+                T: 'a,
+            {
+                let request = sealed::PeripheralChannel::<T, P2M>::request(self);
+                unsafe { transfer_p2m(self, request, src, buf) }
+            }
+        }
+    };
+}
+
+peripherals! {
+    (bdma, DMA1) => {
+        //impl_dma!(DMA1, 0);
+        dma_channels! {
+            ($channel_peri:ident, DMA1, $channel_num:expr) => {
+                impl_dma_channel!($channel_peri, DMAMUX1, $channel_num, 0);
+            };
+        }
+    };
+    (bdma, DMA2) => {
+        //impl_dma!(DMA2, 1);
+        dma_channels! {
+            ($channel_peri:ident, DMA2, $channel_num:expr) => {
+                impl_dma_channel!($channel_peri, DMAMUX1, $channel_num, 1);
+            };
+        }
+    };
+}
+
+macro_rules! impl_usart_dma_requests {
+    ($channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+        dma_requests! {
+            (usart, $peri:ident, RX, $request:expr) => {
+                impl usart::RxDma<peripherals::$peri> for peripherals::$channel_peri { }
+                impl usart::sealed::RxDma<peripherals::$peri> for peripherals::$channel_peri { }
+
+                impl sealed::PeripheralChannel<peripherals::$peri, P2M> for peripherals::$channel_peri {
+                    fn request(&self) -> u8 {
+                        $request
+                    }
+                }
+
+                impl PeripheralChannel<peripherals::$peri, P2M> for peripherals::$channel_peri { }
+
+            };
+
+            (usart, $peri:ident, TX, $request:expr) => {
+                impl usart::TxDma<peripherals::$peri> for peripherals::$channel_peri { }
+                impl usart::sealed::TxDma<peripherals::$peri> for peripherals::$channel_peri { }
+
+                impl sealed::PeripheralChannel<peripherals::$peri, M2P> for peripherals::$channel_peri {
+                    fn request(&self) -> u8 {
+                        $request
+                    }
+                }
+
+                impl PeripheralChannel<peripherals::$peri, M2P> for peripherals::$channel_peri { }
+
+            };
+
+            (uart, $peri:ident, TX, $request:expr) => {
+                impl usart::RxDma<peripherals::$peri> for peripherals::$channel_peri { }
+                impl usart::sealed::RxDma<peripherals::$peri> for peripherals::$channel_peri { }
+
+                impl sealed::PeripheralChannel<peripherals::$peri, P2M> for peripherals::$channel_peri {
+                    fn request(&self) -> u8 {
+                        $request
+                    }
+                }
+
+                impl PeripheralChannel<peripherals::$peri, P2M> for peripherals::$channel_peri { }
+            };
+
+            (uart, $peri:ident, RX, $request:expr) => {
+                impl usart::TxDma<peripherals::$peri> for peripherals::$channel_peri { }
+                impl usart::sealed::TxDma<peripherals::$peri> for peripherals::$channel_peri { }
+
+                impl sealed::PeripheralChannel<peripherals::$peri, M2P> for peripherals::$channel_peri {
+                    fn request(&self) -> u8 {
+                        $request
+                    }
+                }
+
+                impl PeripheralChannel<peripherals::$peri, M2P> for peripherals::$channel_peri { }
+            };
+        }
+
+    };
+}
+
+#[cfg(usart)]
+use crate::usart;
+
+dma_channels! {
+    ($channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+        impl_usart_dma_requests!($channel_peri, $dma_peri, $channel_num);
+    };
+}
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 35a8d3ba..67962fdd 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -30,6 +30,8 @@ pub mod clock;
 pub mod dac;
 #[cfg(any(dma, dmamux))]
 pub mod dma;
+#[cfg(dmamux)]
+pub mod dmamux;
 #[cfg(all(eth, feature = "net"))]
 pub mod eth;
 #[cfg(exti)]
diff --git a/embassy-stm32/src/usart/v3.rs b/embassy-stm32/src/usart/v3.rs
index 1e905144..0071c597 100644
--- a/embassy-stm32/src/usart/v3.rs
+++ b/embassy-stm32/src/usart/v3.rs
@@ -57,7 +57,7 @@ impl<'d, T: Instance> Uart<'d, T> {
         }
     }
 
-    #[cfg(dma)]
+    #[cfg(any(dma, dmamux))]
     pub async fn write_dma(&mut self, ch: &mut impl TxDma<T>, buffer: &[u8]) -> Result<(), Error> {
         unsafe {
             self.inner.regs().cr3().modify(|reg| {
diff --git a/examples/stm32l4/src/bin/usart.rs b/examples/stm32l4/src/bin/usart.rs
index 5b6d9eaa..0b14eeb5 100644
--- a/examples/stm32l4/src/bin/usart.rs
+++ b/examples/stm32l4/src/bin/usart.rs
@@ -82,10 +82,6 @@ fn main() -> ! {
         w.syscfgen().set_bit();
         w
     });
-    //pp.RCC.apb1enr.modify(|_, w| {
-    //w.usart3en().enabled();
-    //w
-    //});
 
     unsafe { embassy::time::set_clock(&ZeroClock) };