Add impl of SectionInterface for Linux GPIO

sprinklers_linux/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "sprinklers_linux"
+version = "0.1.0"
+authors = ["Alex Mikhalev <alexmikhalevalex@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+sprinklers_core = { path = "../sprinklers_core" }
+gpio-cdev = "0.4.0"
+tracing = "0.1.21"
+serde = { version = "1.0.116", features = ["derive"] }
+eyre = "0.6.0"

sprinklers_linux/src/lib.rs

@@ -0,0 +1,75 @@
+use sprinklers_core::section_interface::{SecId, SectionInterface};
+
+use eyre::WrapErr;
+use gpio_cdev::{LineHandle, LineRequestFlags};
+use serde::{Deserialize, Serialize};
+use tracing::{error, trace, warn};
+
+pub struct LinuxGpio {
+    lines: Vec<LineHandle>,
+}
+
+impl SectionInterface for LinuxGpio {
+    fn num_sections(&self) -> SecId {
+        self.lines.len() as SecId
+    }
+
+    fn set_section_state(&self, id: SecId, running: bool) {
+        if let Some(line) = &self.lines.get(id as usize) {
+            trace!(
+                line = line.line().offset(),
+                id,
+                running,
+                "setting state of line"
+            );
+            if let Err(err) = line.set_value(running as u8) {
+                error!("error setting GPIO line value: {}", err);
+            }
+        } else {
+            warn!("set_section_state: invalid section id: {}", id);
+        }
+    }
+
+    fn get_section_state(&self, id: SecId) -> bool {
+        if let Some(line) = &self.lines.get(id as usize) {
+            match line.get_value() {
+                Ok(active) => active != 0,
+                Err(err) => {
+                    error!("error getting GPIO line value: {}", err);
+                    false
+                }
+            }
+        } else {
+            warn!("get_section_state: invalid section id: {}", id);
+            false
+        }
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct LinuxGpioConfig {
+    chip_path: String,
+    line_offsets: Vec<u32>,
+}
+
+impl LinuxGpioConfig {
+    pub fn build(self) -> eyre::Result<LinuxGpio> {
+        let mut chip =
+            gpio_cdev::Chip::new(self.chip_path).wrap_err("could not create gpio_cdev Chip")?;
+        let lines: Result<Vec<_>, eyre::Report> = self
+            .line_offsets
+            .into_iter()
+            .map(|line_offset| {
+                let line = chip
+                    .get_line(line_offset)
+                    .wrap_err("could not get line for chip")?;
+                let line_handle = line
+                    .request(LineRequestFlags::OUTPUT, 0, "sprinklers_rs")
+                    .wrap_err("could not request line access")?;
+                Ok(line_handle)
+            })
+            .collect();
+        let lines = lines?;
+        Ok(LinuxGpio { lines })
+    }
+}