Add CdevPin module

The CdevPin export can be enabled with feature flag "gpio_cdev".

Author: almusil

Cargo.toml

@@ -11,9 +11,11 @@ version = "0.3.0"
 [features]
 default = []
 gpio_sysfs = ["sysfs_gpio"]
+gpio_cdev = ["gpio-cdev"]
 
 [dependencies]
 embedded-hal = { version = "0.2.3", features = ["unproven"] }
+gpio-cdev = { version = "0.2", optional = true }
 sysfs_gpio = { version = "0.5", optional = true }
 
 i2cdev = "0.4.3"

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 CdevPin(pub gpio_cdev::LineHandle, bool);
+
+impl CdevPin {
+    /// 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<Self, gpio_cdev::errors::Error> {
+        let info = handle.line().info()?;
+        Ok(CdevPin(handle, info.is_active_low()))
+    }
+}
+
+impl hal::digital::v2::OutputPin for CdevPin {
+    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 CdevPin {
+    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 CdevPin {
+    type Target = gpio_cdev::LineHandle;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl ops::DerefMut for CdevPin {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}

src/lib.rs

@@ -13,7 +13,10 @@
 #![deny(missing_docs)]
 
 extern crate cast;
+extern crate core;
 extern crate embedded_hal as hal;
+#[cfg(feature = "gpio_cdev")]
+pub extern crate gpio_cdev;
 pub extern crate i2cdev;
 pub extern crate nb;
 pub extern crate serial_core;
@@ -34,10 +37,15 @@ use spidev::SpidevTransfer;
 
 mod serial;
 
+#[cfg(feature = "gpio_cdev")]
+/// Cdev Pin wrapper module
+mod cdev_pin;
 #[cfg(feature = "gpio_sysfs")]
 /// Sysfs Pin wrapper module
 mod sysfs_pin;
 
+#[cfg(feature = "gpio_cdev")]
+pub use cdev_pin::CdevPin;
 pub use serial::Serial;
 #[cfg(feature = "gpio_sysfs")]
 pub use sysfs_pin::SysfsPin;