Add GPIO cdev feature

This feature adds possibility to use newer gpio cdev
instead of deprecated gpio sysfs. At the same time maintains
backward compatibility as default feature set is still using sysfs.

Author: almusil

Cargo.toml

@@ -8,14 +8,20 @@ name = "linux-embedded-hal"
 repository = "https://github.com/japaric/linux-embedded-hal"
 version = "0.3.0"
 
+[features]
+default = ["sysfs_gpio"]
+
+gpio_cdev = ["gpio-cdev"]
+
 [dependencies]
 embedded-hal = { version = "0.2.3", features = ["unproven"] }
 i2cdev = "0.4.3"
 spidev = "0.4"
-sysfs_gpio = "0.5"
 serial-unix = "0.4.0"
 serial-core = "0.4.0"
 nb = "0.1.1"
+sysfs_gpio = { version = "0.5", optional = true }
+gpio-cdev = { version="0.2", optional = true }
 
 [dev-dependencies]
 openpty = "0.1.0"

src/lib.rs

@@ -14,11 +14,14 @@
 
 extern crate cast;
 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;
 pub extern crate serial_unix;
 pub extern crate spidev;
+#[cfg(not(feature = "gpio_cdev"))]
 pub extern crate sysfs_gpio;
 
 use std::io::{self, Write};
@@ -92,11 +95,30 @@ impl hal::blocking::delay::DelayMs<u64> for Delay {
     }
 }
 
+/// 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
+#[cfg(feature = "gpio_cdev")]
+pub struct Pin(pub gpio_cdev::LineHandle, pub bool);
+
+#[cfg(feature = "gpio_cdev")]
+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()))
+    }
+}
+
 /// Newtype around [`sysfs_gpio::Pin`] that implements the `embedded-hal` traits
 ///
 /// [`sysfs_gpio::Pin`]: https://docs.rs/sysfs_gpio/0.5.1/sysfs_gpio/struct.Pin.html
+#[cfg(not(feature = "gpio_cdev"))]
 pub struct Pin(pub sysfs_gpio::Pin);
 
+#[cfg(not(feature = "gpio_cdev"))]
 impl Pin {
     /// See [`sysfs_gpio::Pin::new`][0] for details.
     ///
@@ -117,6 +139,9 @@ impl Pin {
 }
 
 impl hal::digital::v2::OutputPin for Pin {
+    #[cfg(feature = "gpio_cdev")]
+    type Error = gpio_cdev::errors::Error;
+    #[cfg(not(feature = "gpio_cdev"))]
     type Error = sysfs_gpio::Error;
 
     fn set_low(&mut self) -> Result<(), Self::Error> {
@@ -129,8 +154,20 @@ impl hal::digital::v2::OutputPin for Pin {
 }
 
 impl hal::digital::v2::InputPin for Pin {
+    #[cfg(feature = "gpio_cdev")]
+    type Error = gpio_cdev::errors::Error;
+    #[cfg(not(feature = "gpio_cdev"))]
     type Error = sysfs_gpio::Error;
 
+    #[cfg(feature = "gpio_cdev")]
+    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)
+        }
+    }
+    #[cfg(not(feature = "gpio_cdev"))]
     fn is_high(&self) -> Result<bool, Self::Error> {
         if !self.0.get_active_low()? {
             self.0.get_value().map(|val| val != 0)
@@ -145,6 +182,9 @@ impl hal::digital::v2::InputPin for Pin {
 }
 
 impl ops::Deref for Pin {
+    #[cfg(feature = "gpio_cdev")]
+    type Target = gpio_cdev::LineHandle;
+    #[cfg(not(feature = "gpio_cdev"))]
     type Target = sysfs_gpio::Pin;
 
     fn deref(&self) -> &Self::Target {