Merge pull request #28 from hnez/backlight

backlight: dim the backlight when in screensaver mode

openapi.yaml

@@ -41,6 +41,30 @@ paths:
               schema:
                 $ref: '#/components/schemas/Alerts'
 
+  /v1/tac/display/backlight/brightness:
+    get:
+      summary: Get the current backlight brightness (between 0.0, and 1.0)
+      tags: [User Interface]
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                type: number
+    put:
+      summary: Set the current backlight brightness (between 0.0 and 1.0)
+      tags: [User Interface]
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: number
+      responses:
+        '204':
+          description: The display brightness was set sucessfully
+        '400':
+          description: The value could not be parsed as a number
+
   /v1/tac/display/buttons:
     put:
       summary: Simulate a button press/release on the device

src/backlight.rs

@@ -0,0 +1,67 @@
+// This file is part of tacd, the LXA TAC system daemon
+// Copyright (C) 2023 Pengutronix e.K.
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+use anyhow::Result;
+use async_std::prelude::*;
+use async_std::sync::Arc;
+use async_std::task::spawn;
+use log::warn;
+
+mod demo_mode;
+
+#[cfg(feature = "demo_mode")]
+use demo_mode::{Backlight as SysBacklight, Brightness, SysClass};
+
+#[cfg(not(feature = "demo_mode"))]
+use sysfs_class::{Backlight as SysBacklight, Brightness, SysClass};
+
+use crate::broker::{BrokerBuilder, Topic};
+
+pub struct Backlight {
+    pub brightness: Arc<Topic<f32>>,
+}
+
+impl Backlight {
+    pub fn new(bb: &mut BrokerBuilder) -> Result<Self> {
+        let brightness = bb.topic_rw("/v1/tac/display/backlight/brightness", Some(1.0));
+
+        let (mut rx, _) = brightness.clone().subscribe_unbounded();
+
+        let backlight = SysBacklight::new("backlight")?;
+        let max_brightness = backlight.max_brightness()?;
+
+        spawn(async move {
+            while let Some(fraction) = rx.next().await {
+                let brightness = (max_brightness as f32) * fraction;
+                let mut brightness = brightness.clamp(0.0, max_brightness as f32) as u64;
+
+                // A brightness of 0 turns the backlight off completely.
+                // If the user selects something low but not zero they likely
+                // want a dim glow, not completely off.
+                if fraction > 0.01 && brightness == 0 {
+                    brightness = 1;
+                }
+
+                if let Err(e) = backlight.set_brightness(brightness) {
+                    warn!("Failed to set LED pattern: {}", e);
+                }
+            }
+        });
+
+        Ok(Self { brightness })
+    }
+}

src/backlight/demo_mode.rs

@@ -0,0 +1,90 @@
+// This file is part of tacd, the LXA TAC system daemon
+// Copyright (C) 2023 Pengutronix e.K.
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+use std::io::{Error, ErrorKind, Result};
+use std::path::{Path, PathBuf};
+use std::str::{from_utf8, FromStr};
+
+use sysfs_class::{set_trait_method, trait_method};
+
+pub trait SysClass: Sized {
+    fn class() -> &'static str;
+    unsafe fn from_path_unchecked(path: PathBuf) -> Self;
+    fn path(&self) -> &Path;
+
+    fn new(id: &str) -> Result<Self> {
+        let inst = unsafe { Self::from_path_unchecked(id.into()) };
+        Ok(inst)
+    }
+
+    fn read_file<P: AsRef<Path>>(&self, name: P) -> Result<String> {
+        let path = self.path().join(name);
+        let path = path.to_str().unwrap();
+
+        if path == "backlight/max_brightness" {
+            Ok("8".to_string())
+        } else {
+            Err(Error::new(ErrorKind::NotFound, format!("{path} not found")))
+        }
+    }
+
+    fn parse_file<F: FromStr, P: AsRef<Path>>(&self, name: P) -> Result<F> {
+        self.read_file(name)?
+            .parse()
+            .map_err(|_| Error::new(ErrorKind::InvalidData, "too bad"))
+    }
+
+    fn write_file<P: AsRef<Path>, S: AsRef<[u8]>>(&self, name: P, data: S) -> Result<()> {
+        let path = self.path().join(name);
+        let path = path.to_str().unwrap();
+        let data = from_utf8(data.as_ref()).unwrap();
+
+        log::info!("Backlight: Write {} to {}", data, path);
+
+        Ok(())
+    }
+}
+
+pub trait Brightness {
+    fn brightness(&self) -> Result<u64>;
+    fn max_brightness(&self) -> Result<u64>;
+    fn set_brightness(&self, val: u64) -> Result<()>;
+}
+
+pub struct Backlight {
+    path: PathBuf,
+}
+
+impl SysClass for Backlight {
+    fn class() -> &'static str {
+        "backlight"
+    }
+
+    unsafe fn from_path_unchecked(path: PathBuf) -> Self {
+        Self { path }
+    }
+
+    fn path(&self) -> &Path {
+        &self.path
+    }
+}
+
+impl Brightness for Backlight {
+    trait_method!(brightness parse_file u64);
+    trait_method!(max_brightness parse_file u64);
+    set_trait_method!("brightness", set_brightness u64);
+}

src/main.rs

@@ -18,6 +18,7 @@
 use futures::{select, FutureExt};
 
 mod adc;
+mod backlight;
 mod broker;
 mod dbus;
 mod digital_io;
@@ -36,6 +37,7 @@ mod usb_hub;
 mod watchdog;
 
 use adc::Adc;
+use backlight::Backlight;
 use broker::BrokerBuilder;
 use dbus::DbusSession;
 use digital_io::DigitalIo;
@@ -64,6 +66,7 @@ async fn main() -> Result<(), std::io::Error> {
     let mut bb = BrokerBuilder::new();
 
     // Expose hardware on the TAC via the broker framework.
+    let backlight = Backlight::new(&mut bb).unwrap();
     let led = Led::new(&mut bb);
     let adc = Adc::new(&mut bb).await.unwrap();
     let dut_pwr = DutPwrThread::new(
@@ -117,6 +120,7 @@ async fn main() -> Result<(), std::io::Error> {
     let ui = {
         let resources = UiResources {
             adc,
+            backlight,
             dig_io,
             dut_pwr,
             iobus,

src/ui.rs

@@ -39,6 +39,7 @@ use screens::{splash, ActivatableScreen, AlertScreen, NormalScreen, Screen};
 
 pub struct UiResources {
     pub adc: crate::adc::Adc,
+    pub backlight: crate::backlight::Backlight,
     pub dig_io: crate::digital_io::DigitalIo,
     pub dut_pwr: crate::dut_power::DutPwrThread,
     pub iobus: crate::iobus::IoBus,

src/ui/screens/screensaver.rs

@@ -119,6 +119,7 @@ struct Active {
     widgets: WidgetContainer,
     locator: Arc<Topic<bool>>,
     alerts: Arc<Topic<AlertList>>,
+    brightness: Arc<Topic<f32>>,
 }
 
 impl ActivatableScreen for ScreenSaverScreen {
@@ -159,11 +160,16 @@ impl ActivatableScreen for ScreenSaverScreen {
 
         let locator = ui.locator.clone();
         let alerts = ui.alerts.clone();
+        let brightness = ui.res.backlight.brightness.clone();
+
+        // Dim to 10% brightness in screensaver mode
+        brightness.set(0.1);
 
         let active = Active {
             widgets,
             locator,
             alerts,
+            brightness,
         };
 
         Box::new(active)
@@ -177,6 +183,8 @@ impl ActiveScreen for Active {
     }
 
     async fn deactivate(mut self: Box<Self>) -> Display {
+        // Restore full backlight brightness
+        self.brightness.set(1.0);
         self.widgets.destroy().await
     }