Constrain Flex conversions

esp-hal/MIGRATING-0.21.md

@@ -192,3 +192,6 @@ The previous signal function have been replaced by `split`. This change affects
 -let output_signal = gpioN.into_peripheral_output();
 +let (input_signal, output_signal) = gpioN.split();
 ```
+
+`into_peripheral_output`, `split` (for output pins only) and `peripheral_input` have been added to
+the GPIO drivers (`Input`, `Output`, `OutputOpenDrain` and `Flex`) instead.

esp-hal/src/gpio/mod.rs

@@ -1526,14 +1526,6 @@ where
         Self { pin }
     }
 
-    /// Split the pin into an input and output signal.
-    ///
-    /// Peripheral signals allow connecting peripherals together without using
-    /// external hardware.
-    pub fn split(self) -> (interconnect::InputSignal, interconnect::OutputSignal) {
-        self.pin.degrade_pin(private::Internal).split()
-    }
-
     /// Returns a peripheral [input][interconnect::InputSignal] connected to
     /// this pin.
     ///
@@ -1542,16 +1534,6 @@ where
     pub fn peripheral_input(&self) -> interconnect::InputSignal {
         self.pin.degrade_pin(private::Internal).split().0
     }
-
-    /// Turns the pin object into a peripheral
-    /// [output][interconnect::OutputSignal].
-    ///
-    /// The output signal can be passed to peripherals in place of an output
-    /// pin.
-    #[inline]
-    pub fn into_peripheral_output(self) -> interconnect::OutputSignal {
-        self.split().1
-    }
 }
 
 impl<P> Flex<'_, P>
@@ -1701,17 +1683,30 @@ where
     pub fn set_drive_strength(&mut self, strength: DriveStrength) {
         self.pin.set_drive_strength(strength, private::Internal);
     }
-}
 
-impl<P> Flex<'_, P>
-where
-    P: InputPin + OutputPin,
-{
     /// Set the GPIO to open-drain mode.
     pub fn set_as_open_drain(&mut self, pull: Pull) {
         self.pin.set_to_open_drain_output(private::Internal);
         self.pin.pull_direction(pull, private::Internal);
     }
+
+    /// Split the pin into an input and output signal.
+    ///
+    /// Peripheral signals allow connecting peripherals together without using
+    /// external hardware.
+    pub fn split(self) -> (interconnect::InputSignal, interconnect::OutputSignal) {
+        self.pin.degrade_pin(private::Internal).split()
+    }
+
+    /// Turns the pin object into a peripheral
+    /// [output][interconnect::OutputSignal].
+    ///
+    /// The output signal can be passed to peripherals in place of an output
+    /// pin.
+    #[inline]
+    pub fn into_peripheral_output(self) -> interconnect::OutputSignal {
+        self.split().1
+    }
 }
 
 pub(crate) mod internal {