bindings: rust: examples: add dedicated examples

Add rust equivalents of the core examples.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Erik Schilling <erik.schilling@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

bindings/rust/libgpiod/examples/get_line_value.rs

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+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+//
+// Minimal example of reading a single line.
+
+use libgpiod::line;
+
+fn main() -> libgpiod::Result<()> {
+    // example configuration - customize to suit your situation
+    let chip_path = "/dev/gpiochip0";
+    let line_offset = 5;
+
+    let mut lsettings = line::Settings::new()?;
+    lsettings.set_direction(line::Direction::Input)?;
+
+    let mut lconfig = line::Config::new()?;
+    lconfig.add_line_settings(&[line_offset], lsettings)?;
+
+    let mut rconfig = libgpiod::request::Config::new()?;
+    rconfig.set_consumer("get-line-value")?;
+
+    let chip = libgpiod::chip::Chip::open(&chip_path)?;
+    let request = chip.request_lines(Some(&rconfig), &lconfig)?;
+
+    let value = request.value(line_offset)?;
+    println!("{:?}", value);
+    Ok(())
+}

bindings/rust/libgpiod/examples/toggle_line_value.rs

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+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+//
+// Minimal example of toggling a single line.
+
+use libgpiod::line;
+use std::time::Duration;
+
+fn toggle_value(value: line::Value) -> line::Value {
+    match value {
+        line::Value::Active => line::Value::InActive,
+        line::Value::InActive => line::Value::Active,
+    }
+}
+
+fn main() -> libgpiod::Result<()> {
+    // example configuration - customize to suit your situation
+    let chip_path = "/dev/gpiochip0";
+    let line_offset = 5;
+
+    let mut value = line::Value::Active;
+
+    let mut settings = line::Settings::new()?;
+    settings
+        .set_direction(line::Direction::Output)?
+        .set_output_value(value)?;
+
+    let mut lconfig = line::Config::new()?;
+    lconfig.add_line_settings(&[line_offset], settings)?;
+
+    let mut rconfig = libgpiod::request::Config::new()?;
+    rconfig.set_consumer("toggle-line-value")?;
+
+    let chip = libgpiod::chip::Chip::open(&chip_path)?;
+    let mut req = chip.request_lines(Some(&rconfig), &lconfig)?;
+
+    loop {
+        println!("{:?}", value);
+        std::thread::sleep(Duration::from_secs(1));
+        value = toggle_value(value);
+        req.set_value(line_offset, value)?;
+    }
+}

bindings/rust/libgpiod/examples/watch_line_value.rs

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+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+//
+// Minimal example of watching for edges on a single line.
+
+use libgpiod::line;
+use std::time::Duration;
+
+fn main() -> libgpiod::Result<()> {
+    // example configuration - customize to suit your situation
+    let chip_path = "/dev/gpiochip0";
+    let line_offset = 5;
+
+    let mut lsettings = line::Settings::new()?;
+    // assume a button connecting the pin to ground,
+    // so pull it up and provide some debounce.
+    lsettings
+        .set_edge_detection(Some(line::Edge::Both))?
+        .set_bias(Some(line::Bias::PullUp))?
+        .set_debounce_period(Duration::from_millis(10));
+
+    let mut lconfig = line::Config::new()?;
+    lconfig.add_line_settings(&[line_offset], lsettings)?;
+
+    let mut rconfig = libgpiod::request::Config::new()?;
+    rconfig.set_consumer("watch-line-value")?;
+
+    let chip = libgpiod::chip::Chip::open(&chip_path)?;
+    let request = chip.request_lines(Some(&rconfig), &lconfig)?;
+
+    // a larger buffer is an optimisation for reading bursts of events from the
+    // kernel, but that is not necessary in this case, so 1 is fine.
+    let mut buffer = libgpiod::request::Buffer::new(1)?;
+    loop {
+        // blocks until at least one event is available
+        let events = request.read_edge_events(&mut buffer)?;
+        for event in events {
+            let event = event?;
+            println!(
+                "line: {}, type: {}, event #{}",
+                event.line_offset(),
+                match event.event_type()? {
+                    line::EdgeKind::Rising => "Rising ",
+                    line::EdgeKind::Falling => "Falling",
+                },
+                event.line_seqno()
+            );
+        }
+    }
+}