Merge #1191

1191: stm32 gpio implement degrade to AnyPin r=Dirbaio a=JoshMcguigan

This PR implements a `degrade` method on the STM32 GPIO structs `Flex`/`Input`/`Output`/`OutputOpenDrain`. This allows, for example, transforming some `Input<T>` to an `Input<AnyPin>`.

Co-authored-by: Josh Mcguigan <joshmcg88@gmail.com>

embassy-stm32/src/gpio.rs

@@ -28,6 +28,21 @@ impl<'d, T: Pin> Flex<'d, T> {
         Self { pin }
     }
 
+    #[inline]
+    pub fn degrade(mut self) -> Flex<'d, AnyPin> {
+        // Safety: We are about to drop the other copy of this pin, so
+        // this clone is safe.
+        let pin = unsafe { self.pin.clone_unchecked() };
+
+        // We don't want to run the destructor here, because that would
+        // deconfigure the pin.
+        core::mem::forget(self);
+
+        Flex {
+            pin: pin.map_into::<AnyPin>(),
+        }
+    }
+
     /// Put the pin into input mode.
     #[inline]
     pub fn set_as_input(&mut self, pull: Pull) {
@@ -286,6 +301,13 @@ impl<'d, T: Pin> Input<'d, T> {
         Self { pin }
     }
 
+    #[inline]
+    pub fn degrade(self) -> Input<'d, AnyPin> {
+        Input {
+            pin: self.pin.degrade(),
+        }
+    }
+
     #[inline]
     pub fn is_high(&self) -> bool {
         self.pin.is_high()
@@ -345,6 +367,13 @@ impl<'d, T: Pin> Output<'d, T> {
         Self { pin }
     }
 
+    #[inline]
+    pub fn degrade(self) -> Output<'d, AnyPin> {
+        Output {
+            pin: self.pin.degrade(),
+        }
+    }
+
     /// Set the output as high.
     #[inline]
     pub fn set_high(&mut self) {
@@ -407,6 +436,13 @@ impl<'d, T: Pin> OutputOpenDrain<'d, T> {
         Self { pin }
     }
 
+    #[inline]
+    pub fn degrade(self) -> Output<'d, AnyPin> {
+        Output {
+            pin: self.pin.degrade(),
+        }
+    }
+
     #[inline]
     pub fn is_high(&self) -> bool {
         !self.pin.is_low()