Add dma fn read_available and uart-dma-rx example (#116)

* Add dma fn read_available and uart-dma-rx example

* Remove debug code

* Enable circular buffer

* Rename uart-dma example

* DMA: Add some useful methods for checking for trasfer errors

examples/uart-dma-rx.rs

@@ -0,0 +1,94 @@
+#![deny(warnings)]
+#![deny(unsafe_code)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt as rt;
+
+use hal::dma::{config::DmaConfig, stream::DMAExt, TransferExt};
+use hal::prelude::*;
+use hal::pwr::PwrExt;
+use hal::serial::*;
+use hal::{rcc, stm32};
+use stm32g4xx_hal as hal;
+
+use cortex_m_rt::entry;
+use utils::logger::info;
+
+#[macro_use]
+mod utils;
+
+#[entry]
+fn main() -> ! {
+    utils::logger::init();
+
+    info!("Initializing...");
+
+    let dp = stm32::Peripherals::take().expect("cannot take peripherals");
+
+    let rcc = dp.RCC.constrain();
+    let pwr = dp.PWR.constrain().freeze();
+    let mut rcc = rcc.freeze(rcc::Config::hsi(), pwr);
+
+    let streams = dp.DMA1.split(&rcc);
+    let config = DmaConfig::default()
+        .transfer_complete_interrupt(false)
+        .circular_buffer(true)
+        .memory_increment(true);
+
+    info!("Init UART");
+    //let gpioa = dp.GPIOA.split(&mut rcc);
+    //let tx = gpioa.pa2.into_alternate();
+    //let rx = gpioa.pa3.into_alternate();
+    let gpioc = dp.GPIOC.split(&mut rcc);
+    let tx = gpioc.pc10.into_alternate();
+    let rx = gpioc.pc11.into_alternate();
+
+    let usart = dp
+        //.USART2
+        .USART3
+        .usart(
+            tx,
+            rx,
+            FullConfig::default()
+                .baudrate(115200.bps())
+                .receiver_timeout_us(1000), // Timeout after 1ms
+            &mut rcc,
+        )
+        .unwrap();
+
+    //let mut led = gpioa.pa5.into_push_pull_output();
+
+    info!("Start reading");
+
+    let rx_buffer = cortex_m::singleton!(: [u8; 256] = [0; 256]).unwrap();
+
+    let (_tx, rx) = usart.split();
+
+    let mut transfer = streams.0.into_circ_peripheral_to_memory_transfer(
+        rx.enable_dma(),
+        &mut rx_buffer[..],
+        config,
+    );
+
+    transfer.start(|_rx| {});
+    loop {
+        while !transfer.timeout_lapsed() {}
+        transfer.clear_timeout();
+
+        let mut data = [0; 256];
+        loop {
+            let data = transfer.read_available(&mut data);
+            if data.is_empty() {
+                break;
+            }
+            if let Ok(data) = core::str::from_utf8(&*data) {
+                info!("Received: '{}'", data);
+            } else {
+                info!("Received: {:?}", data);
+            }
+            info!("Sup");
+        }
+        //led.toggle().unwrap();
+    }
+}

src/dma/stream.rs

@@ -250,6 +250,13 @@ macro_rules! dma_stream {
                     dma.isr.read().$tcisr().bit_is_set()
                 }
 
+                #[inline(always)]
+                fn get_transfer_error_flag() -> bool {
+                    //NOTE(unsafe) Atomic read with no side effects
+                    let dma = unsafe { &*I::ptr() };
+                    dma.isr.read().$teisr().bit_is_set()
+                }
+
                 #[inline(always)]
                 unsafe fn enable(&mut self) {
                     //NOTE(unsafe) We only access the registers that belongs to the StreamX

src/dma/traits.rs

@@ -47,6 +47,9 @@ pub trait Stream: Sealed {
     /// Get transfer complete flag.
     fn get_transfer_complete_flag() -> bool;
 
+    /// Get transfer error flag.
+    fn get_transfer_error_flag() -> bool;
+
     /// Enable the DMA stream.
     ///
     /// # Safety

src/dma/transfer.rs

@@ -265,6 +265,11 @@ where
         STREAM::get_transfer_complete_flag()
     }
 
+    #[inline(always)]
+    pub fn get_transfer_error_flag(&self) -> bool {
+        STREAM::get_transfer_error_flag()
+    }
+
     /// Clear half transfer interrupt (htif) for the DMA stream.
     #[inline(always)]
     pub fn clear_half_transfer_interrupt(&mut self) {
@@ -378,6 +383,19 @@ where
         read
     }
 
+    pub fn read_available<'a>(
+        &mut self,
+        data: &'a mut [<PERIPHERAL as TargetAddress<PeripheralToMemory>>::MemSize],
+    ) -> &'a mut [<PERIPHERAL as TargetAddress<PeripheralToMemory>>::MemSize] {
+        let blen = unsafe { self.transfer.buf.static_write_buffer().1 };
+        let available = self.elements_available();
+        let len = data.len().min(available).min(blen - 1);
+        let result = &mut data[0..len];
+        self.read_exact(result);
+
+        result
+    }
+
     /// Starts the transfer, the closure will be executed right after enabling
     /// the stream.
     pub fn start<F>(&mut self, f: F)
@@ -424,6 +442,11 @@ where
         self.transfer.get_transfer_complete_flag()
     }
 
+    #[inline(always)]
+    pub fn get_transfer_error_flag(&self) -> bool {
+        self.transfer.get_transfer_error_flag()
+    }
+
     /// Clear half transfer interrupt (htif) for the DMA stream.
     #[inline(always)]
     pub fn clear_half_transfer_interrupt(&mut self) {
@@ -487,6 +510,27 @@ impl_adc_overrun!(ADC3,);
 ))]
 impl_adc_overrun!(ADC4, ADC5,);
 
+macro_rules! impl_serial_timeout {
+    ($($uart:ident, )*) => {$(
+        impl<STREAM, BUF, Pin> CircTransfer<STREAM, crate::serial::Rx<crate::stm32::$uart, Pin, crate::serial::DMA>, BUF>
+        where
+            STREAM: Stream,
+            /*BUF: StaticWriteBuffer + Deref*/ {
+            pub fn timeout_lapsed(&self) -> bool {
+                self.transfer.peripheral.timeout_lapsed()
+            }
+
+            pub fn clear_timeout(&mut self) {
+                self.transfer.peripheral.clear_timeout();
+            }
+        }
+    )*};
+}
+
+impl_serial_timeout!(USART1, USART2, USART3, UART4,);
+#[cfg(not(any(feature = "stm32g431", feature = "stm32g441")))]
+impl_serial_timeout!(UART5,);
+
 pub trait TransferExt<STREAM>
 where
     STREAM: traits::Stream,