feat(kernel): add Port::is_interrupt_line_pending, InterruptLine::is_pending

Author: yvt

src/constance/src/kernel.rs

@@ -315,6 +315,13 @@ pub unsafe trait Port: KernelCfg1 {
     unsafe fn clear_interrupt_line(_line: InterruptNum) -> Result<(), ClearInterruptLineError> {
         Err(ClearInterruptLineError::NotSupported)
     }
+
+    /// Read the pending flag of the specified interrupt line.
+    unsafe fn is_interrupt_line_pending(
+        _line: InterruptNum,
+    ) -> Result<bool, QueryInterruptLineError> {
+        Err(QueryInterruptLineError::NotSupported)
+    }
 }
 
 /// Methods intended to be called by a port.

src/constance/src/kernel/error.rs

@@ -389,3 +389,16 @@ define_error! {
         BadObjectState,
     }
 }
+
+define_error! {
+    /// Error type for [`InterruptLine::is_pending`].
+    ///
+    /// [`InterruptLine::is_pending`]: super::InterruptLine::is_pending
+    pub enum QueryInterruptLineError: BadParamError {
+        /// Reading a pending flag is not supported by the port.
+        NotSupported,
+        /// Reading the pending flag of the specified interrupt line is not
+        /// supported.
+        BadParam,
+    }
+}

src/constance/src/kernel/interrupt.rs

@@ -2,7 +2,7 @@ use core::{fmt, hash, marker::PhantomData};
 
 use super::{
     utils, ClearInterruptLineError, EnableInterruptLineError, Kernel, PendInterruptLineError, Port,
-    SetInterruptLinePriorityError,
+    QueryInterruptLineError, SetInterruptLinePriorityError,
 };
 use crate::utils::Init;
 
@@ -128,6 +128,12 @@ impl<System: Kernel> InterruptLine<System> {
         unsafe { System::clear_interrupt_line(self.0) }
     }
 
+    /// Read the pending flag of the interrupt line.
+    pub fn is_pending(self) -> Result<bool, QueryInterruptLineError> {
+        // Safety: We are the kernel, so it's okay to call `Port`'s methods
+        unsafe { System::is_interrupt_line_pending(self.0) }
+    }
+
     // TODO: port-specific attributes
 }