Add chardev Pin module

The Pin export depends on feature flag with default being
sysfs, "gpio_cdev" will export cdev Pin.

Author: almusil

Cargo.toml

@@ -8,6 +8,10 @@ name = "linux-embedded-hal"
 repository = "https://github.com/japaric/linux-embedded-hal"
 version = "0.3.0"
 
+[features]
+default = []
+gpio_cdev = []
+
 [dependencies]
 embedded-hal = { version = "0.2.3", features = ["unproven"] }
 i2cdev = "0.4.3"
@@ -16,6 +20,7 @@ sysfs_gpio = "0.5"
 serial-unix = "0.4.0"
 serial-core = "0.4.0"
 nb = "0.1.1"
+gpio-cdev = "0.2"
 
 [dev-dependencies]
 openpty = "0.1.0"

src/cdev_pin.rs

@@ -0,0 +1,58 @@
+use core::ops;
+
+/// Newtype around [`gpio_cdev::LineHandle`] that implements the `embedded-hal` traits
+///
+/// [`gpio_cdev::LineHandle`]: https://docs.rs/gpio-cdev/0.2.0/gpio_cdev/struct.LineHandle.html
+pub struct Pin(pub gpio_cdev::LineHandle, bool);
+
+impl Pin {
+    /// See [`gpio_cdev::Line::request`][0] for details.
+    ///
+    /// [0]: https://docs.rs/gpio-cdev/0.2.0/gpio_cdev/struct.Line.html#method.request
+    pub fn new(handle: gpio_cdev::LineHandle) -> Result<Pin, gpio_cdev::errors::Error> {
+        let info = handle.line().info()?;
+        Ok(Pin(handle, info.is_active_low()))
+    }
+}
+
+impl hal::digital::v2::OutputPin for Pin {
+    type Error = gpio_cdev::errors::Error;
+
+    fn set_low(&mut self) -> Result<(), Self::Error> {
+        self.0.set_value(0)
+    }
+
+    fn set_high(&mut self) -> Result<(), Self::Error> {
+        self.0.set_value(1)
+    }
+}
+
+impl hal::digital::v2::InputPin for Pin {
+    type Error = gpio_cdev::errors::Error;
+
+    fn is_high(&self) -> Result<bool, Self::Error> {
+        if !self.1 {
+            self.0.get_value().map(|val| val != 0)
+        } else {
+            self.0.get_value().map(|val| val == 0)
+        }
+    }
+
+    fn is_low(&self) -> Result<bool, Self::Error> {
+        self.is_high().map(|val| !val)
+    }
+}
+
+impl ops::Deref for Pin {
+    type Target = gpio_cdev::LineHandle;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl ops::DerefMut for Pin {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}

src/lib.rs

@@ -13,7 +13,9 @@
 #![deny(missing_docs)]
 
 extern crate cast;
+extern crate core;
 extern crate embedded_hal as hal;
+pub extern crate gpio_cdev;
 pub extern crate i2cdev;
 pub extern crate nb;
 pub extern crate serial_core;
@@ -33,10 +35,15 @@ use spidev::SpidevTransfer;
 
 mod serial;
 
+/// Cdev Pin wrapper module
+pub mod cdev_pin;
 /// Sysfs Pin wrapper module
 pub mod sysfs_pin;
 
+#[cfg(feature = "gpio_cdev")]
+pub use cdev_pin::Pin;
 pub use serial::Serial;
+#[cfg(not(feature = "gpio_cdev"))]
 pub use sysfs_pin::Pin;
 
 /// Empty struct that provides delay functionality on top of `thread::sleep`