[WIP] Sketch out an API for managing interrupts

src/common.rs

@@ -60,6 +60,29 @@ pub trait PortDriverPullUp: PortDriver {
     fn set_pull_up(&mut self, mask: u32, enable: bool) -> Result<(), Self::Error>;
 }
 
+pub trait PortDriverIrqChange: PortDriver {
+    /// Read which pins changed state since the last interrupt request.
+    ///
+    /// This method should reset the pin-change state such that a consecutive call does not report
+    /// the same pins again.
+    fn fetch_interrupt_changed(&mut self) -> Result<u32, Self::Error>;
+}
+
+
+pub trait PortDriverIrqState: PortDriver {
+    /// Read the state of pins at the last interrupt request.
+    ///
+    /// This method should reset the pin-change state such that a consecutive call does not report
+    /// the same pins again.
+    ///
+    /// The return value is a tuple of
+    ///
+    /// 1. The mask of pins that changed state (must be the same value that would have been
+    ///    reported by fetch_interrupt_changed())
+    /// 2. For the changed pins, the individual state that was latched at change time.
+    fn fetch_interrupt_state(&mut self) -> Result<(u32, u32), Self::Error>;
+}
+
 /// Pin Modes
 pub mod mode {
     /// Trait for pin-modes which can be used to set a logic level.

src/lib.rs

@@ -69,6 +69,8 @@ pub use bus::I2cBus;
 pub use common::mode;
 pub use multi::read_multiple;
 pub use multi::write_multiple;
+pub use multi::fetch_pin_change;
+pub use multi::fetch_interrupt_state;
 pub use mutex::PortMutex;
 pub use pin::Pin;
 
@@ -80,6 +82,8 @@ pub(crate) use common::PortDriverPolarity;
 pub(crate) use common::PortDriverPullDown;
 pub(crate) use common::PortDriverPullUp;
 pub(crate) use common::PortDriverTotemPole;
+pub(crate) use common::PortDriverIrqChange;
+pub(crate) use common::PortDriverIrqState;
 
 pub use dev::max7321::Max7321;
 pub use dev::mcp23x17::Mcp23x17;

src/multi.rs

@@ -113,6 +113,48 @@ where
     Ok(ret)
 }
 
+pub fn fetch_pin_change<PD, MUTEX, MODE: crate::mode::HasInput, const N: usize>(
+    pins: [&crate::Pin<'_, MODE, MUTEX>; N],
+) -> Result<[bool; N], PD::Error>
+where
+    PD: crate::PortDriver + crate::PortDriverIrqChange,
+    MUTEX: crate::PortMutex<Port = PD>,
+{
+    let port_driver = pins[0].port_driver();
+    let mask_in = port_driver.lock(|drv| drv.fetch_interrupt_changed())?;
+
+    let mut ret = [false; N];
+    for (pin, state) in pins.iter().zip(ret.iter_mut()) {
+        assert!(core::ptr::eq(pin.port_driver(), port_driver));
+        *state = mask_in & pin.pin_mask() != 0;
+    }
+
+    Ok(ret)
+}
+
+pub fn fetch_interrupt_state<PD, MUTEX, MODE: crate::mode::HasInput, const N: usize>(
+    pins: [&crate::Pin<'_, MODE, MUTEX>; N],
+) -> Result<[Option<bool>; N], PD::Error>
+where
+    PD: crate::PortDriver + crate::PortDriverIrqState,
+    MUTEX: crate::PortMutex<Port = PD>,
+{
+    let port_driver = pins[0].port_driver();
+    let (mask_changed, mask_state) = port_driver.lock(|drv| drv.fetch_interrupt_state())?;
+
+    let mut ret = [None; N];
+    for (pin, state) in pins.iter().zip(ret.iter_mut()) {
+        assert!(core::ptr::eq(pin.port_driver(), port_driver));
+        *state = if mask_changed & pin.pin_mask() != 0 {
+            Some(mask_state & pin.pin_mask() != 0)
+        } else {
+            None
+        };
+    }
+
+    Ok(ret)
+}
+
 #[cfg(test)]
 mod tests {
     use embedded_hal_mock::eh1::i2c as mock_i2c;