Add battery

src/app.rs

@@ -32,7 +32,7 @@ use crate::helpers::{load_json, load_toml, save_toml, IsHidden};
 use crate::settings::{ButtonScheme, Settings, SETTINGS_PATH, RotationLock};
 use crate::frontlight::{Frontlight, StandardFrontlight, NaturalFrontlight, PremixedFrontlight, FakeFrontlight};
 use crate::lightsensor::{LightSensor, KoboLightSensor};
-use crate::battery::{Battery, FakeBattery};
+use crate::battery::{Battery, RemarkableBattery};
 use crate::geom::{Rectangle, Edge};
 use crate::view::home::Home;
 use crate::view::reader::Reader;
@@ -243,7 +243,7 @@ fn build_context(fb: Box<dyn Framebuffer>) -> Result<Context, Error> {
 
     let fonts = Fonts::load().context("Can't load fonts.")?;
 
-    let battery = Box::new(FakeBattery::new()) as Box<dyn Battery>;
+    let battery = Box::new(RemarkableBattery::new().context("Can't create battery.")?) as Box<dyn Battery>;
 
     let lightsensor = if CURRENT_DEVICE.has_lightsensor() {
         Box::new(KoboLightSensor::new().context("Can't create light sensor.")?) as Box<dyn LightSensor>

src/battery/mod.rs

@@ -1,10 +1,12 @@
 mod kobo;
 mod fake;
+mod remarkable;
 
 use anyhow::Error;
 
 pub use self::kobo::KoboBattery;
 pub use self::fake::FakeBattery;
+pub use self::remarkable::RemarkableBattery;
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum Status {

src/battery/remarkable.rs

@@ -0,0 +1,47 @@
+use std::io::{Read, Seek, SeekFrom};
+use std::fs::File;
+use std::path::Path;
+use super::{Battery, Status};
+use anyhow::{Error, format_err};
+
+const BATTERY_INTERFACE: &str = "/sys/class/power_supply/bq27441-0";
+
+const BATTERY_CAPACITY: &str = "capacity";
+const BATTERY_STATUS: &str = "status";
+
+// TODO: health, technology, time_to_full_now, time_to_empty_now
+pub struct RemarkableBattery {
+    capacity: File,
+    status: File,
+}
+
+impl RemarkableBattery {
+    pub fn new() -> Result<RemarkableBattery, Error> {
+        let base = Path::new(BATTERY_INTERFACE);
+        let capacity = File::open(base.join(BATTERY_CAPACITY))?;
+        let status = File::open(base.join(BATTERY_STATUS))?;
+        Ok(RemarkableBattery { capacity, status })
+    }
+}
+
+impl Battery for RemarkableBattery {
+    fn capacity(&mut self) -> Result<f32, Error> {
+        let mut buf = String::new();
+        self.capacity.seek(SeekFrom::Start(0))?;
+        self.capacity.read_to_string(&mut buf)?;
+        Ok(buf.trim_end().parse::<f32>().unwrap_or(0.0))
+    }
+
+    fn status(&mut self) -> Result<Status, Error> {
+        let mut buf = String::new();
+        self.status.seek(SeekFrom::Start(0))?;
+        self.status.read_to_string(&mut buf)?;
+        match buf.trim_end() {
+            "Discharging" => Ok(Status::Discharging),
+            "Charging" => Ok(Status::Charging),
+            "Not charging" | "Full" => Ok(Status::Charged),
+            _ => Err(format_err!("Unknown battery status.")),
+
+        }
+    }
+}