Add support for character device GPIO

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
 - Added serial::Read/Write implementation.
+- Added feature flag for Chardev GPIO
 
 ### Fixed
 
@@ -23,6 +24,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Use embedded-hal::digital::v2 traits.
 - Updated to i2cdev 0.4.3 (necessary for trasactional write-read).
 - Updated to spidev 0.4
+- Added feature flag for Sysfs GPIO
 
 ## [v0.2.2] - 2018-12-21
 

Cargo.toml

@@ -8,11 +8,18 @@ name = "linux-embedded-hal"
 repository = "https://github.com/japaric/linux-embedded-hal"
 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"
 spidev = "0.4"
-sysfs_gpio = "0.5"
 serial-unix = "0.4.0"
 serial-core = "0.4.0"
 nb = "0.1.1"

README.md

@@ -8,6 +8,20 @@ This project is developed and maintained by the [Embedded Linux team][team].
 
 ## [Documentation](https://docs.rs/linux-embedded-hal)
 
+## GPIO character device
+
+Since Linux kernel v4.4 the use of sysfs GPIO was deprecated and replaced by the character device GPIO.
+See [gpio-cdev documentation](https://github.com/rust-embedded/gpio-cdev#sysfs-gpio-vs-gpio-character-device) for details.
+
+This crate includes feature flag `gpio_cdev` that exposes `CdevPin` as wrapper around `LineHandle` from [gpio-cdev](https://crates.io/crates/gpio-cdev).
+To enable it update your Cargo.toml. Please note that in order to prevent `LineHandle` fd from closing you should
+assign to a variable, see [cdev issue](https://github.com/rust-embedded/gpio-cdev/issues/29) for more details.  
+```
+linux-embedded-hal = { version = "0.3", features = ["gpio_cdev"] }
+``` 
+
+`SysfsPin` can be still used with feature flag `gpio_sysfs`.
+
 ## License
 
 Licensed under either of

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

@@ -13,13 +13,17 @@
 #![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;
+pub extern crate serial_unix;
 pub extern crate spidev;
+#[cfg(feature = "gpio_sysfs")]
 pub extern crate sysfs_gpio;
-pub extern crate serial_unix;
-pub extern crate serial_core;
-pub extern crate nb;
 
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
@@ -33,7 +37,18 @@ 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;
 
 /// Empty struct that provides delay functionality on top of `thread::sleep`
 pub struct Delay;
@@ -92,72 +107,6 @@ impl hal::blocking::delay::DelayMs<u64> for Delay {
     }
 }
 
-/// 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
-pub struct Pin(pub sysfs_gpio::Pin);
-
-impl Pin {
-    /// See [`sysfs_gpio::Pin::new`][0] for details.
-    ///
-    /// [0]: https://docs.rs/sysfs_gpio/0.5.1/sysfs_gpio/struct.Pin.html#method.new
-    pub fn new(pin_num: u64) -> Pin {
-        Pin(sysfs_gpio::Pin::new(pin_num))
-    }
-
-    /// See [`sysfs_gpio::Pin::from_path`][0] for details.
-    ///
-    /// [0]: https://docs.rs/sysfs_gpio/0.5.1/sysfs_gpio/struct.Pin.html#method.from_path
-    pub fn from_path<P>(path: P) -> sysfs_gpio::Result<Pin>
-    where
-        P: AsRef<Path>,
-    {
-        sysfs_gpio::Pin::from_path(path).map(Pin)
-    }
-}
-
-impl hal::digital::v2::OutputPin for Pin {
-    type Error = sysfs_gpio::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 = sysfs_gpio::Error;
-
-    fn is_high(&self) -> Result<bool, Self::Error> {
-        if !self.0.get_active_low()? {
-            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 = sysfs_gpio::Pin;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl ops::DerefMut for Pin {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
-    }
-}
-
 /// Newtype around [`i2cdev::linux::LinuxI2CDevice`] that implements the `embedded-hal` traits
 ///
 /// [`i2cdev::linux::LinuxI2CDevice`]: https://docs.rs/i2cdev/0.3.1/i2cdev/linux/struct.LinuxI2CDevice.html
@@ -220,10 +169,7 @@ impl hal::blocking::i2c::WriteRead for I2cdev {
         buffer: &mut [u8],
     ) -> Result<(), Self::Error> {
         self.set_address(address)?;
-        let mut messages = [
-            LinuxI2CMessage::write(bytes),
-            LinuxI2CMessage::read(buffer),
-        ];
+        let mut messages = [LinuxI2CMessage::write(bytes), LinuxI2CMessage::read(buffer)];
         self.inner.transfer(&mut messages).map(drop)
     }
 }

src/sysfs_pin.rs

@@ -0,0 +1,68 @@
+use std::ops;
+use std::path::Path;
+
+/// 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
+pub struct SysfsPin(pub sysfs_gpio::Pin);
+
+impl SysfsPin {
+    /// See [`sysfs_gpio::Pin::new`][0] for details.
+    ///
+    /// [0]: https://docs.rs/sysfs_gpio/0.5.1/sysfs_gpio/struct.Pin.html#method.new
+    pub fn new(pin_num: u64) -> Self {
+        SysfsPin(sysfs_gpio::Pin::new(pin_num))
+    }
+
+    /// See [`sysfs_gpio::Pin::from_path`][0] for details.
+    ///
+    /// [0]: https://docs.rs/sysfs_gpio/0.5.1/sysfs_gpio/struct.Pin.html#method.from_path
+    pub fn from_path<P>(path: P) -> sysfs_gpio::Result<Self>
+    where
+        P: AsRef<Path>,
+    {
+        sysfs_gpio::Pin::from_path(path).map(SysfsPin)
+    }
+}
+
+impl hal::digital::v2::OutputPin for SysfsPin {
+    type Error = sysfs_gpio::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 SysfsPin {
+    type Error = sysfs_gpio::Error;
+
+    fn is_high(&self) -> Result<bool, Self::Error> {
+        if !self.0.get_active_low()? {
+            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 SysfsPin {
+    type Target = sysfs_gpio::Pin;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl ops::DerefMut for SysfsPin {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}