Added the missing DMA implementations for USART3

Author: rudib

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
 - `Into<serial::Config>` for `Bps` [#387]
+- Added the missing DMA implementations for USART3 [#373]
 - `count_down` constructor for `Timer` -> `CountDownTimer` without start [#382]
 - Implementation of RTIC Monotonic for TIM2 & TIM5 under `rtic` feature [#380] [#390]
 - `IoPin` for `Output<OpenDrain>> <-> Input<Floating>>` [#374]
@@ -18,6 +19,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   with `internal_pull_up` [#399]
 
 [#390]: https://github.com/stm32-rs/stm32f4xx-hal/pull/390
+[#373]: https://github.com/stm32-rs/stm32f4xx-hal/pull/373
 [#382]: https://github.com/stm32-rs/stm32f4xx-hal/pull/382
 [#380]: https://github.com/stm32-rs/stm32f4xx-hal/pull/380
 [#374]: https://github.com/stm32-rs/stm32f4xx-hal/pull/374

src/dma/traits.rs

@@ -754,8 +754,11 @@ dma_map!(
     (Stream7<DMA2>, 7, DMAR<pac::TIM8>, MemoryToPeripheral), //TIM8_COM/TRIG
     (Stream7<DMA2>, 7, DMAR<pac::TIM8>, PeripheralToMemory), //TIM8_COM/TRIG
     (Stream1<DMA1>, 4, pac::USART3, PeripheralToMemory),     //USART3_RX
+    (Stream1<DMA1>, 4, serial::Rx<pac::USART3>, PeripheralToMemory), //USART3_RX
     (Stream3<DMA1>, 4, pac::USART3, MemoryToPeripheral),     //USART3_TX
+    (Stream3<DMA1>, 4, serial::Tx<pac::USART3>, MemoryToPeripheral), //USART3_TX
     (Stream4<DMA1>, 7, pac::USART3, MemoryToPeripheral),     //USART3_TX:DMA_CHANNEL_7
+    (Stream4<DMA1>, 7, serial::Tx<pac::USART3>, MemoryToPeripheral), //USART3_TX:DMA_CHANNEL_7
 );
 
 #[cfg(any(