# libgpiod in Rust

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Rust crate for interfacing with Linux GPIO character devices.

It provides an interface to the Linux GPIO using the chardev module.
This interface involves calling [ioctl](https://man7.org/linux/man-pages/man2/ioctl.2.html) funcions which are unsafe and require some unintuitive variable mapping.
To ease this process, this crate provides a [Chip] struct which encapsulates the interface in safe Rust functions.
The functionality provided here is highly inspired by [libgpiod](https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/).

Since all functionality is dependent on Linux function calls, this crate only compiles for Linux systems.

## ABI compatibility

Both ABI v1 (linux >= 4.0) and v2 (linux >= v5.10) supported but edge detection implemented for v2 only.
Deprecated sysfs-based API (linux < 4.0) currently is not supported at all.

## Crates

- [gpiod-core](https://crates.io/crates/gpiod-core) - core abstractions and low level interface (not for end users)
- **[gpiod](https://crates.io/crates/gpiod)** - sync interface which supports synchronous operation only
- [tokio-gpiod](https://crates.io/crates/tokio-gpiod) - async interface for [tokio](https://tokio.rs/) fans
- [async-gpiod](https://crates.io/crates/async-gpiod) - async interface to use with non-tokio async runtimes

## Usage examples

Input values:

```rust,no_run
use gpiod::{Chip, Options, Masked, AsValuesMut};

fn main() -> std::io::Result<()> {
    let chip = Chip::new(0)?; // open chip

    let opts = Options::input([27, 3, 11]) // configure lines offsets
        .consumer("my-inputs"); // optionally set consumer string

    let inputs = chip.request_lines(opts)?;

    // get all three values
    let values = inputs.get_values([false; 3])?;

    println!("values: {:?}", values);

    // get second value only
    let values = inputs.get_values([None, Some(false), None])?;

    println!("values: {:?}", values);

    // get values via bits
    let values = inputs.get_values(0u8)?;

    println!("values: {:#b}", values);

    // get only second value via bits
    let values = inputs.get_values(Masked::<u8>::default().with(1, Some(false)))?;

    println!("values: {:#b}", values);

    Ok(())
}
```

Output values:

```rust,no_run
use gpiod::{Chip, Options, Masked, AsValuesMut};

fn main() -> std::io::Result<()> {
    let chip = Chip::new("gpiochip0")?; // open chip

    let opts = Options::output([9, 21]) // configure lines offsets
        .values([false, true]) // optionally set initial values
        .consumer("my-outputs"); // optionally set consumer string

    let outputs = chip.request_lines(opts)?;

    // set all two values
    outputs.set_values([true, false])?;

    // set second value only
    outputs.set_values([None, Some(false)])?;

    // set values from bits
    outputs.set_values(0b01u8)?;

    // set only second value from bits
    outputs.set_values(Masked::<u8>::default().with(1, Some(true)))?;

    Ok(())
}
```

Monitor values:

```rust,no_run
use gpiod::{Chip, Options, EdgeDetect};

fn main() -> std::io::Result<()> {
    let chip = Chip::new("gpiochip0")?; // open chip

    let opts = Options::input([4, 7]) // configure lines offsets
        .edge(EdgeDetect::Both) // configure edges to detect
        .consumer("my-inputs"); // optionally set consumer string

    let mut inputs = chip.request_lines(opts)?;

    loop {
        let event = inputs.read_event()?;

        println!("event: {:?}", event);
    }

    Ok(())
}
```