add Trigger trait

This is a simple interface which models an object that can generate
a single event. Each attempt to trigger the event may return an error,
which is defined by an associated type.

Signed-off-by: Alexandru Agache <[email protected]>

src/interrupt/mod.rs

@@ -0,0 +1,13 @@
+// Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+
+use std::result::Result;
+
+/// Abstraction for a simple, push-button like interrupt mechanism.
+pub trait Trigger {
+    /// Underlying type for the potential error conditions returned by `Self::trigger`.
+    type E;
+
+    /// Trigger an event.
+    fn trigger(&self) -> Result<(), Self::E>;
+}

src/lib.rs

@@ -6,6 +6,7 @@
 use std::cmp::{Ord, Ordering, PartialOrd};
 
 pub mod device_manager;
+pub mod interrupt;
 pub mod resources;
 
 // IO Size.