11 files changed, 244 insertions, 255 deletions

diff --git a/embassy-stm32/src/bdma/mod.rs b/embassy-stm32/src/bdma/mod.rs
index 1a49f4e1d..ae7e9d238 100644
--- a/embassy-stm32/src/bdma/mod.rs
+++ b/embassy-stm32/src/bdma/mod.rs
@@ -6,25 +6,3 @@ mod _version;
 
 #[allow(unused)]
 pub use _version::*;
-
-use core::future::Future;
-
-pub trait WriteDma<T> {
-    type WriteDmaFuture<'a>: Future<Output = ()> + 'a
-    where
-        Self: 'a;
-
-    fn transfer<'a>(&'a mut self, buf: &'a [u8], dst: *mut u8) -> Self::WriteDmaFuture<'a>
-    where
-        T: 'a;
-}
-
-pub trait ReadDma<T> {
-    type ReadDmaFuture<'a>: Future<Output = ()> + 'a
-    where
-        Self: 'a;
-
-    fn transfer<'a>(&'a mut self, src: *const u8, buf: &'a mut [u8]) -> Self::ReadDmaFuture<'a>
-    where
-        T: 'a;
-}
diff --git a/embassy-stm32/src/bdma/v1.rs b/embassy-stm32/src/bdma/v1.rs
index f81a08768..fd3bf699c 100644
--- a/embassy-stm32/src/bdma/v1.rs
+++ b/embassy-stm32/src/bdma/v1.rs
@@ -6,10 +6,11 @@ use embassy::interrupt::{Interrupt, InterruptExt};
 use embassy::util::{AtomicWaker, OnDrop};
 use futures::future::poll_fn;
 
-use super::{ReadDma, WriteDma};
+use crate::dma_traits::{ReadDma, WriteDma};
 use crate::interrupt;
 use crate::pac;
 use crate::pac::bdma::vals;
+use crate::rcc::sealed::RccPeripheral;
 
 const CH_COUNT: usize = pac::peripheral_count!(DMA) * 8;
 const CH_STATUS_NONE: u8 = 0;
@@ -57,6 +58,9 @@ pub(crate) async unsafe fn transfer_p2m(
         while regs.cr().read().en() {}
     });
 
+    #[cfg(dmamux)]
+    crate::dmamux::configure_channel(1, 2);
+
     regs.par().write_value(src as u32);
     regs.mar().write_value(dst.as_mut_ptr() as u32);
     regs.ndtr().write(|w| w.set_ndt(dst.len() as u16));
@@ -88,6 +92,9 @@ pub(crate) async unsafe fn transfer_m2p(
     state_number: usize,
     src: &[u8],
     dst: *mut u8,
+    #[cfg(dmamux)] dmamux_regs: &'static pac::dmamux::Dmamux,
+    #[cfg(dmamux)] dmamux_ch_num: u8,
+    #[cfg(dmamux)] request: u8,
 ) {
     // ndtr is max 16 bits.
     assert!(src.len() <= 0xFFFF);
@@ -105,6 +112,9 @@ pub(crate) async unsafe fn transfer_m2p(
         while regs.cr().read().en() {}
     });
 
+    #[cfg(dmamux)]
+    crate::dmamux::configure_dmamux(dmamux_regs, dmamux_ch_num, request);
+
     regs.par().write_value(dst as u32);
     regs.mar().write_value(src.as_ptr() as u32);
     regs.ndtr().write(|w| w.set_ndt(src.len() as u16));
@@ -161,9 +171,10 @@ pub(crate) unsafe fn init() {
     }
     pac::peripherals! {
         (bdma, DMA1) => {
-            critical_section::with(|_| {
-                pac::RCC.ahbenr().modify(|w| w.set_dmaen(true));
-            });
+            //critical_section::with(|_| {
+                //pac::RCC.ahbenr().modify(|w| w.set_dmaen(true));
+            //});
+            crate::peripherals::DMA1::enable();
         };
     }
 }
@@ -220,8 +231,10 @@ macro_rules! impl_dma_channel {
             }
         }
 
+        #[cfg(not(dmamux))]
         impl<T> WriteDma<T> for crate::peripherals::$channel_peri
         where
+            Self: crate::dmamux::sealed::PeripheralChannel<T, crate::dmamux::M2P>,
             T: 'static,
         {
             type WriteDmaFuture<'a> = impl Future<Output = ()>;
@@ -234,10 +247,47 @@ macro_rules! impl_dma_channel {
 
                 let state_num = self.state_num();
                 let regs = self.regs();
+
                 unsafe { transfer_m2p(regs, state_num, buf, dst) }
             }
         }
 
+        #[cfg(dmamux)]
+        impl<T> WriteDma<T> for crate::peripherals::$channel_peri
+        where
+            Self: crate::dmamux::sealed::PeripheralChannel<T, crate::dmamux::M2P>,
+            T: 'static,
+        {
+            type WriteDmaFuture<'a> = impl Future<Output = ()>;
+
+            fn transfer<'a>(&'a mut self, buf: &'a [u8], dst: *mut u8) -> Self::WriteDmaFuture<'a>
+            where
+                T: 'a,
+            {
+                use sealed::Channel as _Channel;
+
+                let state_num = self.state_num();
+                let regs = self.regs();
+
+                use crate::dmamux::sealed::Channel as _MuxChannel;
+                use crate::dmamux::sealed::PeripheralChannel;
+                let dmamux_regs = self.dmamux_regs();
+                let dmamux_ch_num = self.dma_ch_num();
+                let request = PeripheralChannel::<T, crate::dmamux::M2P>::request(self);
+                unsafe {
+                    transfer_m2p(
+                        regs,
+                        state_num,
+                        buf,
+                        dst,
+                        dmamux_regs,
+                        dmamux_ch_num,
+                        request,
+                    )
+                }
+            }
+        }
+
         impl<T> ReadDma<T> for crate::peripherals::$channel_peri
         where
             T: 'static,
@@ -292,6 +342,8 @@ pac::interrupts! {
 
 #[cfg(usart)]
 use crate::usart;
+
+#[cfg(not(dmamux))]
 pac::peripheral_dma_channels! {
     ($peri:ident, usart, $kind:ident, RX, $channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
         impl usart::RxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
@@ -302,4 +354,34 @@ pac::peripheral_dma_channels! {
         impl usart::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
         impl usart::sealed::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
     };
+
+    ($peri:ident, uart, $kind:ident, RX, $channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+        impl usart::RxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+        impl usart::sealed::RxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+    };
+
+    ($peri:ident, uart, $kind:ident, TX, $channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+        impl usart::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+        impl usart::sealed::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+    };
+}
+
+#[cfg(dmamux)]
+pac::peripherals! {
+    (usart, $peri:ident) => {
+        pac::dma_channels! {
+            ($channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+                impl usart::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+                impl usart::sealed::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+            };
+        }
+    };
+    (uart, $peri:ident) => {
+        pac::dma_channels! {
+            ($channel_peri:ident, $dma_peri:ident, $channel_num:expr) => {
+                impl usart::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+                impl usart::sealed::TxDma<crate::peripherals::$peri> for crate::peripherals::$channel_peri { }
+            };
+        }
+    };
 }
diff --git a/embassy-stm32/src/dma/mod.rs b/embassy-stm32/src/dma/mod.rs
index 466cfa033..ed080cd16 100644
--- a/embassy-stm32/src/dma/mod.rs
+++ b/embassy-stm32/src/dma/mod.rs
@@ -1,6 +1,5 @@
 #![macro_use]
 
-#[cfg(dma)]
 #[cfg_attr(dma_v1, path = "v1.rs")]
 #[cfg_attr(dma_v2, path = "v2.rs")]
 mod _version;
@@ -8,25 +7,3 @@ mod _version;
 #[cfg(dma)]
 #[allow(unused)]
 pub use _version::*;
-
-use core::future::Future;
-
-pub trait WriteDma<T> {
-    type WriteDmaFuture<'a>: Future<Output = ()> + 'a
-    where
-        Self: 'a;
-
-    fn transfer<'a>(&'a mut self, buf: &'a [u8], dst: *mut u8) -> Self::WriteDmaFuture<'a>
-    where
-        T: 'a;
-}
-
-pub trait ReadDma<T> {
-    type ReadDmaFuture<'a>: Future<Output = ()> + 'a
-    where
-        Self: 'a;
-
-    fn transfer<'a>(&'a mut self, src: *const u8, buf: &'a mut [u8]) -> Self::ReadDmaFuture<'a>
-    where
-        T: 'a;
-}
diff --git a/embassy-stm32/src/dma/v2.rs b/embassy-stm32/src/dma/v2.rs
index e7cd24710..5080776fb 100644
--- a/embassy-stm32/src/dma/v2.rs
+++ b/embassy-stm32/src/dma/v2.rs
@@ -1,5 +1,6 @@
 use core::task::Poll;
 
+use crate::dma_traits::{ReadDma, WriteDma};
 use atomic_polyfill::{AtomicU8, Ordering};
 use embassy::interrupt::{Interrupt, InterruptExt};
 use embassy::util::AtomicWaker;
diff --git a/embassy-stm32/src/dma_traits.rs b/embassy-stm32/src/dma_traits.rs
new file mode 100644
index 000000000..8f1a9f40e
--- /dev/null
+++ b/embassy-stm32/src/dma_traits.rs
@@ -0,0 +1,21 @@
+use core::future::Future;
+
+pub trait WriteDma<T> {
+    type WriteDmaFuture<'a>: Future<Output = ()> + 'a
+    where
+        Self: 'a;
+
+    fn transfer<'a>(&'a mut self, buf: &'a [u8], dst: *mut u8) -> Self::WriteDmaFuture<'a>
+    where
+        T: 'a;
+}
+
+pub trait ReadDma<T> {
+    type ReadDmaFuture<'a>: Future<Output = ()> + 'a
+    where
+        Self: 'a;
+
+    fn transfer<'a>(&'a mut self, src: *const u8, buf: &'a mut [u8]) -> Self::ReadDmaFuture<'a>
+    where
+        T: 'a;
+}
diff --git a/embassy-stm32/src/dmamux/mod.rs b/embassy-stm32/src/dmamux/mod.rs
index b4d5b9831..745906cdd 100644
--- a/embassy-stm32/src/dmamux/mod.rs
+++ b/embassy-stm32/src/dmamux/mod.rs
@@ -20,41 +20,11 @@ use crate::peripherals;
 
 use core::future::Future;
 
-use crate::dma::{ReadDma, WriteDma};
+use crate::dma_traits::{ReadDma, WriteDma};
 
-const CH_COUNT: usize = peripheral_count!(DMA) * 8;
-const CH_STATUS_NONE: u8 = 0;
-const CH_STATUS_COMPLETED: u8 = 1;
-const CH_STATUS_ERROR: u8 = 2;
-
-struct State {
-    ch_wakers: [AtomicWaker; CH_COUNT],
-    ch_status: [AtomicU8; CH_COUNT],
-}
-
-impl State {
-    const fn new() -> Self {
-        const AW: AtomicWaker = AtomicWaker::new();
-        const AU: AtomicU8 = AtomicU8::new(CH_STATUS_NONE);
-        Self {
-            ch_wakers: [AW; CH_COUNT],
-            ch_status: [AU; CH_COUNT],
-        }
-    }
-}
-
-static STATE: State = State::new();
-
-#[allow(unused)]
-pub(crate) async unsafe fn transfer_p2m(
-    ch: &mut impl Channel,
-    ch_func: u8,
-    src: *const u8,
-    dst: &mut [u8],
-) {
-    unimplemented!()
-}
+pub(crate) fn configure_channel(ch_num: u8, request_num: u8) {}
 
+/*
 #[allow(unused)]
 pub(crate) async unsafe fn transfer_m2p(
     ch: &mut impl Channel,
@@ -128,22 +98,36 @@ pub(crate) async unsafe fn transfer_m2p(
     // TODO handle error
     assert!(res == CH_STATUS_COMPLETED);
 }
+ */
+
+pub(crate) unsafe fn configure_dmamux(
+    dmamux_regs: &pac::dmamux::Dmamux,
+    dmamux_ch_num: u8,
+    request: u8,
+) {
+    let ch_mux_regs = dmamux_regs.ccr(dmamux_ch_num as _);
+    ch_mux_regs.write(|reg| {
+        // one request?
+        reg.set_nbreq(0);
+        reg.set_dmareq_id(request);
+    });
+
+    ch_mux_regs.modify(|reg| {
+        reg.set_ege(true);
+        //reg.set_se(true);
+        //reg.set_soie(true);
+    });
+}
 
 pub(crate) mod sealed {
     use super::*;
 
-    pub trait Bdma {
-        fn regs() -> &'static pac::bdma::Dma;
-        fn num() -> u8;
-    }
-
     pub trait DmaMux {
         fn regs() -> &'static pac::dmamux::Dmamux;
     }
 
     pub trait Channel {
         fn num(&self) -> usize;
-        fn regs(&self) -> pac::bdma::Ch;
         fn dma_regs() -> &'static pac::bdma::Dma;
         fn dma_ch_num(&self) -> u8;
 
@@ -156,7 +140,6 @@ pub(crate) mod sealed {
     }
 }
 
-pub trait Bdma: sealed::Bdma {}
 pub trait DmaMux: sealed::DmaMux {}
 pub trait Channel: sealed::Channel {}
 pub trait PeripheralChannel<PERI, OP>: sealed::Channel {}
@@ -172,10 +155,6 @@ macro_rules! impl_dma_channel {
                 ($dma_num * 8) + $channel_num
             }
 
-            fn regs(&self) -> pac::bdma::Ch {
-                Self::dma_regs().ch(self.dma_ch_num() as _)
-            }
-
             fn dma_regs() -> &'static pac::bdma::Dma {
                 &crate::pac::$dma_peri
             }
@@ -192,42 +171,6 @@ macro_rules! impl_dma_channel {
                 ($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) }
-            }
-        }
     };
 }
 
@@ -242,25 +185,8 @@ macro_rules! impl_dmamux {
     };
 }
 
-macro_rules! impl_bdma {
-    ($peri:ident, $dma_num:expr) => {
-        impl sealed::Bdma for peripherals::$peri {
-            fn num() -> u8 {
-                $dma_num
-            }
-
-            fn regs() -> &'static pac::bdma::Dma {
-                &pac::$peri
-            }
-        }
-
-        impl Bdma for peripherals::$peri {}
-    };
-}
-
 peripherals! {
     (bdma, DMA1) => {
-        impl_bdma!(DMA1, 0);
         dma_channels! {
             ($channel_peri:ident, DMA1, $channel_num:expr) => {
                 impl_dma_channel!($channel_peri, DMAMUX1, $channel_num, DMA1, 0);
@@ -268,7 +194,6 @@ peripherals! {
         }
     };
     (bdma, DMA2) => {
-        impl_bdma!(DMA2, 1);
         dma_channels! {
             ($channel_peri:ident, DMA2, $channel_num:expr) => {
                 impl_dma_channel!($channel_peri, DMAMUX1, $channel_num, DMA2, 1);
@@ -285,9 +210,6 @@ macro_rules! impl_usart_dma_requests {
         dma_requests! {
             // TODO: DRY this up.
             (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
@@ -299,9 +221,6 @@ macro_rules! impl_usart_dma_requests {
             };
 
             (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
@@ -313,9 +232,6 @@ macro_rules! impl_usart_dma_requests {
             };
 
             (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
@@ -326,9 +242,6 @@ macro_rules! impl_usart_dma_requests {
             };
 
             (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
@@ -351,86 +264,5 @@ dma_channels! {
     };
 }
 
-unsafe fn on_irq() {
-    defmt::info!("irq fire");
-    peripherals! {
-        //(bdma, $dma:ident) => {
-        (bdma, DMA1) => {
-            defmt::info!("---> dma DMA1");
-            //for isrn in 0..2 {
-                //let isr = pac::$dma.isr(isrn).read();
-                let isr = pac::DMA1.isr().read();
-                pac::DMA1.ifcr().write_value(isr);
-                let dman = <peripherals::DMA1 as sealed::Bdma>::num() as usize;
-
-                for chn in 0..8 {
-                    let n = dman * 8 + chn;
-                    defmt::info!("n={}", n);
-                    if isr.teif(chn) {
-                        defmt::info!("transfer error");
-                        STATE.ch_status[n].store(CH_STATUS_ERROR, Ordering::Release);
-                        STATE.ch_wakers[n].wake();
-                    } else if isr.tcif(chn) {
-                        defmt::info!("transfer complete");
-                        STATE.ch_status[n].store(CH_STATUS_COMPLETED, Ordering::Release);
-                        STATE.ch_wakers[n].wake();
-                    } else if isr.htif(chn) {
-                        defmt::info!("half transfer");
-                    } else if isr.gif(chn) {
-                        defmt::info!("half transfer");
-                    }
-                }
-            //}
-        };
-
-        (bdma, DMA2) => {
-            defmt::info!("---> dma DMA2");
-            //for isrn in 0..2 {
-                //let isr = pac::$dma.isr(isrn).read();
-                let isr = pac::DMA2.isr().read();
-                pac::DMA2.ifcr().write_value(isr);
-                let dman = <peripherals::DMA2 as sealed::Bdma>::num() as usize;
-
-                for chn in 0..8 {
-                    let n = dman * 8 + chn;
-                    defmt::info!("n={}", n);
-                    if isr.teif(chn) {
-                        defmt::info!("transfer error");
-                        STATE.ch_status[n].store(CH_STATUS_ERROR, Ordering::Release);
-                        STATE.ch_wakers[n].wake();
-                    } else if isr.tcif(chn) {
-                        defmt::info!("transfer complete");
-                        STATE.ch_status[n].store(CH_STATUS_COMPLETED, Ordering::Release);
-                        STATE.ch_wakers[n].wake();
-                    } else if isr.htif(chn) {
-                        defmt::info!("half transfer");
-                    } else if isr.gif(chn) {
-                        defmt::info!("half transfer");
-                    }
-                }
-            //}
-        };
-
-    }
-    defmt::info!("irq fire complete");
-}
-
 /// safety: must be called only once
-pub(crate) unsafe fn init() {
-    interrupts! {
-        (DMA, $irq:ident) => {
-            defmt::info!("enable irq {}", stringify!($irq));
-            interrupt::$irq::steal().enable();
-        };
-    }
-}
-
-interrupts! {
-    (DMA, $irq:ident) => {
-        #[crate::interrupt]
-        unsafe fn $irq () {
-            defmt::info!("irq firing {}", stringify!($irq));
-            on_irq()
-        }
-    };
-}
+pub(crate) unsafe fn init() {}
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index f750c9899..4b2826ae8 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -20,6 +20,9 @@ pub mod gpio;
 pub mod rcc;
 
 // Sometimes-present hardware
+#[cfg(any(dma, bdma, dmamux))]
+pub mod dma_traits;
+
 #[cfg(adc)]
 pub mod adc;
 #[cfg(bdma)]
@@ -28,7 +31,7 @@ pub mod bdma;
 pub mod clock;
 #[cfg(dac)]
 pub mod dac;
-#[cfg(any(dma, dmamux))]
+#[cfg(dma)]
 pub mod dma;
 #[cfg(dmamux)]
 pub mod dmamux;
diff --git a/embassy-stm32/src/usart/mod.rs b/embassy-stm32/src/usart/mod.rs
index 2bab4016f..ddaed5bb9 100644
--- a/embassy-stm32/src/usart/mod.rs
+++ b/embassy-stm32/src/usart/mod.rs
@@ -73,11 +73,8 @@ pub enum Error {
 pub(crate) mod sealed {
     use super::*;
 
-    #[cfg(any(dma, dmamux))]
-    use crate::dma::WriteDma;
-
-    #[cfg(bdma)]
-    use crate::bdma::WriteDma;
+    #[cfg(any(dma, bdma, dmamux))]
+    use crate::dma_traits::WriteDma;
 
     pub trait Instance {
         fn regs(&self) -> crate::pac::usart::Usart;
diff --git a/examples/stm32l4/src/bin/usart_dma.rs b/examples/stm32l4/src/bin/usart_dma.rs
new file mode 100644
index 000000000..cc630e0df
--- /dev/null
+++ b/examples/stm32l4/src/bin/usart_dma.rs
@@ -0,0 +1,96 @@
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use core::fmt::Write;
+use cortex_m_rt::entry;
+use embassy::executor::Executor;
+use embassy::time::Clock;
+use embassy::util::Forever;
+use embassy_stm32::usart::{Config, Uart};
+use example_common::*;
+use heapless::String;
+use stm32l4::stm32l4x5 as pac;
+
+#[embassy::task]
+async fn main_task() {
+    let mut p = embassy_stm32::init(Default::default());
+
+    let config = Config::default();
+    let mut usart = Uart::new(p.UART4, p.PA1, p.PA0, config);
+
+    for n in 0u32.. {
+        let mut s: String<128> = String::new();
+        core::write!(&mut s, "Hello DMA World {}!\r\n", n).unwrap();
+
+        usart
+            .write_dma(&mut p.DMA1_3, s.as_bytes())
+            .await
+            .unwrap();
+        info!("wrote DMA");
+    }
+}
+
+struct ZeroClock;
+
+impl Clock for ZeroClock {
+    fn now(&self) -> u64 {
+        0
+    }
+}
+
+static EXECUTOR: Forever<Executor> = Forever::new();
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World!");
+
+    let pp = pac::Peripherals::take().unwrap();
+
+    pp.DBGMCU.cr.modify(|_, w| {
+        w.dbg_sleep().set_bit();
+        w.dbg_standby().set_bit();
+        w.dbg_stop().set_bit()
+    });
+
+    pp.RCC.ahb1enr.modify(|_, w| {
+        unsafe {
+            w.bits( 0x07 );
+        }
+        w
+        //w.dmamuxen().set_bit();
+        //w.dma1en().set_bit();
+        //w.dma2en().set_bit();
+        //w
+    });
+
+    pp.RCC.ahb2enr.modify(|_, w| {
+        w.gpioaen().set_bit();
+        w.gpioben().set_bit();
+        w.gpiocen().set_bit();
+        w.gpioden().set_bit();
+        w.gpioeen().set_bit();
+        w.gpiofen().set_bit();
+        w
+    });
+
+    pp.RCC.apb2enr.modify(|_, w| {
+        w.syscfgen().set_bit();
+        w
+    });
+
+
+    unsafe { embassy::time::set_clock(&ZeroClock) };
+
+    let executor = EXECUTOR.put(Executor::new());
+
+    executor.run(|spawner| {
+        unwrap!(spawner.spawn(main_task()));
+    })
+}
diff --git a/stm32-data b/stm32-data
-Subproject 409ed5502c254e462f3e31b0ea5ddee95f818a7
+Subproject a2167373ee8fd0e75dce003bfdbadda8b32ff77
diff --git a/stm32-metapac-gen/src/lib.rs b/stm32-metapac-gen/src/lib.rs
index 978f70b92..3f6a03fcc 100644
--- a/stm32-metapac-gen/src/lib.rs
+++ b/stm32-metapac-gen/src/lib.rs
@@ -421,14 +421,16 @@ pub fn gen(options: Options) {
                                     clock.to_ascii_lowercase()
                                 };
 
-                                peripheral_rcc_table.push(vec![
-                                    name.clone(),
-                                    clock,
-                                    enable_reg.to_ascii_lowercase(),
-                                    reset_reg.to_ascii_lowercase(),
-                                    format!("set_{}", enable_field.to_ascii_lowercase()),
-                                    format!("set_{}", reset_field.to_ascii_lowercase()),
-                                ]);
+                                if !name.starts_with("GPIO") {
+                                    peripheral_rcc_table.push(vec![
+                                        name.clone(),
+                                        clock,
+                                        enable_reg.to_ascii_lowercase(),
+                                        reset_reg.to_ascii_lowercase(),
+                                        format!("set_{}", enable_field.to_ascii_lowercase()),
+                                        format!("set_{}", reset_field.to_ascii_lowercase()),
+                                    ]);
+                                }
                             }
                             (None, Some(_)) => {
                                 print!("Unable to find enable register for {}", name)