stm32: fix refcounts for usart, spi, and i2c

embassy-stm32/src/i2c/v1.rs

@@ -339,6 +339,12 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
     }
 }
 
+impl<'d, T: Instance, TXDMA, RXDMA> Drop for I2c<'d, T, TXDMA, RXDMA> {
+    fn drop(&mut self) {
+        T::disable();
+    }
+}
+
 impl<'d, T: Instance> embedded_hal_02::blocking::i2c::Read for I2c<'d, T> {
     type Error = Error;
 

embassy-stm32/src/i2c/v2.rs

@@ -838,6 +838,12 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
     }
 }
 
+impl<'d, T: Instance, TXDMA, RXDMA> Drop for I2c<'d, T, TXDMA, RXDMA> {
+    fn drop(&mut self) {
+        T::disable();
+    }
+}
+
 mod eh02 {
     use super::*;
 

embassy-stm32/src/spi/mod.rs

@@ -646,6 +646,8 @@ impl<'d, T: Instance, Tx, Rx> Drop for Spi<'d, T, Tx, Rx> {
         self.sck.as_ref().map(|x| x.set_as_disconnected());
         self.mosi.as_ref().map(|x| x.set_as_disconnected());
         self.miso.as_ref().map(|x| x.set_as_disconnected());
+
+        T::disable();
     }
 }
 

embassy-stm32/src/usart/buffered.rs

@@ -124,6 +124,8 @@ impl<'d, T: BasicInstance> BufferedUart<'d, T> {
         rx_buffer: &'d mut [u8],
         config: Config,
     ) -> BufferedUart<'d, T> {
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 
@@ -143,6 +145,8 @@ impl<'d, T: BasicInstance> BufferedUart<'d, T> {
     ) -> BufferedUart<'d, T> {
         into_ref!(cts, rts);
 
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 
@@ -169,6 +173,8 @@ impl<'d, T: BasicInstance> BufferedUart<'d, T> {
     ) -> BufferedUart<'d, T> {
         into_ref!(de);
 
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 
@@ -382,6 +388,8 @@ impl<'d, T: BasicInstance> Drop for BufferedUartRx<'d, T> {
                 T::Interrupt::disable();
             }
         }
+
+        T::disable();
     }
 }
 
@@ -397,6 +405,8 @@ impl<'d, T: BasicInstance> Drop for BufferedUartTx<'d, T> {
                 T::Interrupt::disable();
             }
         }
+
+        T::disable();
     }
 }
 

embassy-stm32/src/usart/mod.rs

@@ -618,6 +618,18 @@ impl<'d, T: BasicInstance, RxDma> UartRx<'d, T, RxDma> {
     }
 }
 
+impl<'d, T: BasicInstance, TxDma> Drop for UartTx<'d, T, TxDma> {
+    fn drop(&mut self) {
+        T::disable();
+    }
+}
+
+impl<'d, T: BasicInstance, TxDma> Drop for UartRx<'d, T, TxDma> {
+    fn drop(&mut self) {
+        T::disable();
+    }
+}
+
 impl<'d, T: BasicInstance, TxDma, RxDma> Uart<'d, T, TxDma, RxDma> {
     pub fn new(
         peri: impl Peripheral<P = T> + 'd,
@@ -628,6 +640,8 @@ impl<'d, T: BasicInstance, TxDma, RxDma> Uart<'d, T, TxDma, RxDma> {
         rx_dma: impl Peripheral<P = RxDma> + 'd,
         config: Config,
     ) -> Self {
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 
@@ -647,6 +661,8 @@ impl<'d, T: BasicInstance, TxDma, RxDma> Uart<'d, T, TxDma, RxDma> {
     ) -> Self {
         into_ref!(cts, rts);
 
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 
@@ -672,6 +688,8 @@ impl<'d, T: BasicInstance, TxDma, RxDma> Uart<'d, T, TxDma, RxDma> {
     ) -> Self {
         into_ref!(de);
 
+        // UartRx and UartTx have one refcount ea.
+        T::enable();
         T::enable();
         T::reset();
 

embassy-stm32/src/usart/ringbuffered.rs

@@ -1,4 +1,5 @@
 use core::future::poll_fn;
+use core::mem;
 use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::Poll;
 
@@ -24,12 +25,16 @@ impl<'d, T: BasicInstance, RxDma: super::RxDma<T>> UartRx<'d, T, RxDma> {
         let request = self.rx_dma.request();
         let opts = Default::default();
 
-        let ring_buf = unsafe { ReadableRingBuffer::new_read(self.rx_dma, request, rdr(T::regs()), dma_buf, opts) };
+        // Safety: we forget the struct before this function returns.
+        let rx_dma = unsafe { self.rx_dma.clone_unchecked() };
+        let _peri = unsafe { self._peri.clone_unchecked() };
 
-        RingBufferedUartRx {
-            _peri: self._peri,
-            ring_buf,
-        }
+        let ring_buf = unsafe { ReadableRingBuffer::new_read(rx_dma, request, rdr(T::regs()), dma_buf, opts) };
+
+        // Don't disable the clock
+        mem::forget(self);
+
+        RingBufferedUartRx { _peri, ring_buf }
     }
 }
 
@@ -186,6 +191,8 @@ impl<'d, T: BasicInstance, RxDma: super::RxDma<T>> RingBufferedUartRx<'d, T, RxD
 impl<T: BasicInstance, RxDma: super::RxDma<T>> Drop for RingBufferedUartRx<'_, T, RxDma> {
     fn drop(&mut self) {
         self.teardown_uart();
+
+        T::disable();
     }
 }
 /// Return an error result if the Sr register has errors