Implement InputPin for Output<OpenDrain> pins

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Implement `InputPin` for `Output<OpenDrain>` pins ([#114](https://github.com/stm32-rs/stm32f3xx-hal/pull/114))
+
 ### Fixed
 
 - `PLL` was calculated wrong for devices, which do not divide `HSI` ([#67](https://github.com/stm32-rs/stm32f3xx-hal/pull/67))
@@ -28,7 +32,7 @@ let clocks = rcc
     .use_hse(32.mhz())
     .sysclk(72.mhz())
 ```
-  This is possible through utilizing the divider, which can devide the
+  This is possible through utilizing the divider, which can divide the
   external oscillator clock on most devices. Some devices have even the
   possibility to divide the internal oscillator clock.
 

src/gpio.rs

@@ -206,6 +206,31 @@ macro_rules! gpio {
             }
         }
 
+        #[cfg(feature = "unproven")]
+        impl InputPin for PXx<Output<OpenDrain>> {
+            type Error = Infallible;
+
+            fn is_high(&self) -> Result<bool, Self::Error> {
+                Ok(!self.is_low()?)
+            }
+
+             fn is_low(&self) -> Result<bool, Self::Error> {
+                // NOTE(unsafe) atomic read with no side effects
+                Ok(unsafe {
+                    match &self.gpio {
+                        $(
+                            #[cfg(all(any(
+                                $(feature = $device,)+
+                            ), not(any(
+                                $(feature = $device_except,)*
+                            ))))]
+                            Gpio::$GPIOX => (*$GPIOX::ptr()).idr.read().bits() & (1 << self.i) == 0,
+                        )+
+                    }
+                })
+            }
+        }
+
         #[cfg(feature = "unproven")]
         impl <MODE> StatefulOutputPin for PXx<Output<MODE>> {
             fn is_set_high(&self) -> Result<bool, Self::Error> {
@@ -412,6 +437,20 @@ macro_rules! gpio {
                     }
                 }
 
+                #[cfg(feature = "unproven")]
+                impl InputPin for $PXx<Output<OpenDrain>> {
+                    type Error = Infallible;
+
+                    fn is_high(&self) -> Result<bool, Self::Error> {
+                        Ok(!self.is_low()?)
+                    }
+
+                     fn is_low(&self) -> Result<bool, Self::Error> {
+                        // NOTE(unsafe) atomic read with no side effects
+                        Ok(unsafe { (*$GPIOX::ptr()).idr.read().bits() & (1 << self.i) == 0 })
+                    }
+                }
+
                 #[cfg(feature = "unproven")]
                 impl<MODE> StatefulOutputPin for $PXx<Output<MODE>> {
                     fn is_set_high(&self) -> Result<bool, Self::Error> {
@@ -598,6 +637,20 @@ macro_rules! gpio {
                         }
                     }
 
+                    #[cfg(feature = "unproven")]
+                    impl InputPin for $PXi<Output<OpenDrain>> {
+                        type Error = Infallible;
+
+                        fn is_high(&self) -> Result<bool, Self::Error> {
+                            Ok(!self.is_low()?)
+                        }
+
+                         fn is_low(&self) -> Result<bool, Self::Error> {
+                            // NOTE(unsafe) atomic read with no side effects
+                            Ok(unsafe { (*$GPIOX::ptr()).idr.read().$idri().is_low()})
+                        }
+                    }
+
                     #[cfg(feature = "unproven")]
                     impl<MODE> StatefulOutputPin for $PXi<Output<MODE>> {
                         fn is_set_high(&self) -> Result<bool, Self::Error> {