api: initial gpio apis for review

src/lib.rs

@@ -1,3 +1,71 @@
-#[test]
-fn it_works() {
+// Copyright 2015, Paul Osborne <[email protected]>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/license/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option.  This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Generic Interface for GPIOs Across Many Systems
+//!
+//! This crate provides a set of core traits and related types
+//! for accessing GPIOs across a variety of systems.  The goal
+//! is that devices may be written depending on these traits
+//! and consequently be portable to various systems.
+
+#![crate_type = "lib"]
+#![crate_name = "gpio"]
+
+// until core is stabilized, we need some hacks to support
+// both nightly and stable
+#![cfg_attr(nightly, feature(no_std))]
+#![cfg_attr(nightly, no_std)]
+
+#[cfg(any(not(nightly), test))]
+#[macro_use] extern crate std as core;
+
+/// Indication that an error occurred with a GPIO operation
+#[derive(Copy, Clone)]
+pub enum Error {
+    /// The GPIO was configured as an input but an output action was attempted
+    IllegalOperationOnInput,
+    /// The GPIO was configured as an output but an input action was attempted
+    IllegalOperationOnOutput,
+    /// Some other error occurred
+    Other(&'static str),
+}
+
+/// GPIO Result
+pub type Result<T> = core::result::Result<T, Error>;
+
+/// The direction of a GPIO Pin
+#[derive(Copy, Clone)]
+pub enum Direction {
+    /// The pin is an input
+    In,
+    /// The pin is an output
+    Out,
+}
+
+/// The logic level of a GPIO Pin
+#[derive(Copy, Clone, PartialEq)]
+pub enum Level {
+    /// Logic low
+    Low,
+    /// Logic high
+    High,
+}
+
+/// Generic trait providing access to a single GPIO
+pub trait Gpio {
+    /// Get the currently configured direciton of this GPIO
+    fn get_direction(&self) -> Result<Direction>;
+    /// Set the pin to be an input
+    fn set_input(&mut self) -> Result<()>;
+    /// Set the pin to be an output with the provided level
+    fn set_output(&mut self, value: Level) -> Result<()>;
+    /// Get the current level of this GPIO (input only)
+    fn get_level(&self) -> Result<Level>;
+    /// Set the current level of this GPIO (output only)
+    fn set_level(&mut self, value: Level) -> Result<()>;
 }