Simplify PinGuard and reduce its size

esp-hal/src/gpio/interconnect.rs

@@ -393,13 +393,6 @@ impl Signal<'_> {
         }
     }
 
-    fn connect_with_guard(self, signal: crate::gpio::OutputSignal) -> PinGuard {
-        match self {
-            Signal::Pin(pin) => PinGuard::new(pin, signal),
-            Signal::Level(_) => PinGuard::new_unconnected(signal),
-        }
-    }
-
     fn connect_to_peripheral_input(
         &self,
         signal: gpio::InputSignal,
@@ -864,7 +857,10 @@ impl<'d> OutputSignal<'d> {
     #[instability::unstable]
     pub(crate) fn connect_with_guard(self, signal: crate::gpio::OutputSignal) -> PinGuard {
         signal.connect_to(&self);
-        self.pin.connect_with_guard(signal)
+        match self.pin {
+            Signal::Pin(pin) => PinGuard::new(pin),
+            Signal::Level(_) => PinGuard::new_unconnected(),
+        }
     }
 
     delegate::delegate! {

esp-hal/src/gpio/mod.rs

@@ -64,6 +64,7 @@ crate::unstable_module! {
     #[cfg(all(soc_has_rtc_io, not(esp32)))]
     pub mod rtc_io;
 }
+use interconnect::PeripheralOutput;
 
 mod asynch;
 mod embedded_hal_impls;
@@ -99,24 +100,19 @@ pub(crate) static GPIO_LOCK: RawMutex = RawMutex::new();
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub(crate) struct PinGuard {
     pin: u8,
-    signal: OutputSignal,
 }
 
 impl crate::private::Sealed for PinGuard {}
 
 impl PinGuard {
-    pub(crate) fn new(pin: AnyPin<'_>, signal: OutputSignal) -> Self {
-        Self {
-            pin: pin.number(),
-            signal,
-        }
+    // This must only be used with a pin currently configured for output, and the PinGuard must be
+    // dropped before the pin can be reconfigured (e.g. for input).
+    fn new(pin: AnyPin<'_>) -> Self {
+        Self { pin: pin.number() }
     }
 
-    pub(crate) fn new_unconnected(signal: OutputSignal) -> Self {
-        Self {
-            pin: u8::MAX,
-            signal,
-        }
+    pub(crate) fn new_unconnected() -> Self {
+        Self { pin: u8::MAX }
     }
 
     #[allow(unused)]
@@ -133,7 +129,7 @@ impl Drop for PinGuard {
     fn drop(&mut self) {
         if self.pin != u8::MAX {
             let pin = unsafe { AnyPin::steal(self.pin) };
-            self.signal.disconnect_from(&pin);
+            pin.disconnect_from_peripheral_output();
         }
     }
 }

esp-hal/src/i2c/master/mod.rs

@@ -715,8 +715,8 @@ impl<'d> I2c<'d, Blocking> {
     pub fn new(i2c: impl Instance + 'd, config: Config) -> Result<Self, ConfigError> {
         let guard = PeripheralGuard::new(i2c.info().peripheral);
 
-        let sda_pin = PinGuard::new_unconnected(i2c.info().sda_output);
-        let scl_pin = PinGuard::new_unconnected(i2c.info().scl_output);
+        let sda_pin = PinGuard::new_unconnected();
+        let scl_pin = PinGuard::new_unconnected();
 
         let mut i2c = I2c {
             i2c: i2c.degrade(),

esp-hal/src/spi/master.rs

@@ -616,16 +616,16 @@ struct SpiPinGuard {
     cs_pin: PinGuard,
     sio0_pin: PinGuard,
     sio1_pin: PinGuard,
-    sio2_pin: Option<PinGuard>,
-    sio3_pin: Option<PinGuard>,
+    sio2_pin: PinGuard,
+    sio3_pin: PinGuard,
     #[cfg(spi_master_has_octal)]
-    sio4_pin: Option<PinGuard>,
+    sio4_pin: PinGuard,
     #[cfg(spi_master_has_octal)]
-    sio5_pin: Option<PinGuard>,
+    sio5_pin: PinGuard,
     #[cfg(spi_master_has_octal)]
-    sio6_pin: Option<PinGuard>,
+    sio6_pin: PinGuard,
     #[cfg(spi_master_has_octal)]
-    sio7_pin: Option<PinGuard>,
+    sio7_pin: PinGuard,
 }
 
 /// Configuration errors.
@@ -710,20 +710,20 @@ impl<'d> Spi<'d, Blocking> {
             _mode: PhantomData,
             guard,
             pins: SpiPinGuard {
-                sclk_pin: PinGuard::new_unconnected(spi.info().sclk),
-                cs_pin: PinGuard::new_unconnected(spi.info().cs(0)),
-                sio0_pin: PinGuard::new_unconnected(spi.info().sio_output(0)),
-                sio1_pin: PinGuard::new_unconnected(spi.info().sio_output(1)),
-                sio2_pin: spi.info().opt_sio_output(2).map(PinGuard::new_unconnected),
-                sio3_pin: spi.info().opt_sio_output(3).map(PinGuard::new_unconnected),
+                sclk_pin: PinGuard::new_unconnected(),
+                cs_pin: PinGuard::new_unconnected(),
+                sio0_pin: PinGuard::new_unconnected(),
+                sio1_pin: PinGuard::new_unconnected(),
+                sio2_pin: PinGuard::new_unconnected(),
+                sio3_pin: PinGuard::new_unconnected(),
                 #[cfg(spi_master_has_octal)]
-                sio4_pin: spi.info().opt_sio_output(4).map(PinGuard::new_unconnected),
+                sio4_pin: PinGuard::new_unconnected(),
                 #[cfg(spi_master_has_octal)]
-                sio5_pin: spi.info().opt_sio_output(5).map(PinGuard::new_unconnected),
+                sio5_pin: PinGuard::new_unconnected(),
                 #[cfg(spi_master_has_octal)]
-                sio6_pin: spi.info().opt_sio_output(6).map(PinGuard::new_unconnected),
+                sio6_pin: PinGuard::new_unconnected(),
                 #[cfg(spi_master_has_octal)]
-                sio7_pin: spi.info().opt_sio_output(7).map(PinGuard::new_unconnected),
+                sio7_pin: PinGuard::new_unconnected(),
             },
             spi: spi.degrade(),
         };
@@ -922,7 +922,7 @@ macro_rules! def_with_sio_pin {
         #[doc = concat!(" to the SIO", stringify!($n), " output and input signals.")]
         #[instability::unstable]
         pub fn $fn(mut self, sio: impl PeripheralOutput<'d>) -> Self {
-            self.pins.$field = Some(self.connect_sio_pin(sio.into(), $n));
+            self.pins.$field = self.connect_sio_pin(sio.into(), $n);
 
             self
         }

esp-hal/src/uart/mod.rs

@@ -469,8 +469,8 @@ where
 
         let mem_guard = create_mem_guard(unsafe { self.uart.clone_unchecked() });
 
-        let rts_pin = PinGuard::new_unconnected(self.uart.info().rts_signal);
-        let tx_pin = PinGuard::new_unconnected(self.uart.info().tx_signal);
+        let rts_pin = PinGuard::new_unconnected();
+        let tx_pin = PinGuard::new_unconnected();
 
         let mut serial = Uart {
             rx: UartRx {