Read stylus battery level

Tested on Linux with USI stylus.
Hardcoded to our firmware with report ID. Guaranteed won't work on other
systems.
I assume it will work on Windows with USI.
It won't work with MPP styluses.

Signed-off-by: Daniel Schaefer <dhs@frame.work>

Author: JohnAZoidberg

EXAMPLES.md

@@ -138,3 +138,10 @@ ALS:   76 Lux
   APU:          42 C
   Fan Speed:       0 RPM
 ```
+
+## Stylus (Framework 12)
+
+```
+> sudo framework_tool --stylus-battery
+Stylus Battery Strength: 77%
+```

framework_lib/src/commandline/clap_std.rs

@@ -184,6 +184,11 @@ struct ClapCli {
     #[arg(long)]
     touchscreen_enable: Option<bool>,
 
+    /// Check stylus battery level (USI 2.0 stylus only)
+    #[clap(value_enum)]
+    #[arg(long)]
+    stylus_battery: bool,
+
     /// Get EC console, choose whether recent or to follow the output
     #[clap(value_enum)]
     #[arg(long)]
@@ -360,6 +365,7 @@ pub fn parse(args: &[String]) -> Cli {
         rgbkbd: args.rgbkbd,
         tablet_mode: args.tablet_mode,
         touchscreen_enable: args.touchscreen_enable,
+        stylus_battery: args.stylus_battery,
         console: args.console,
         reboot_ec: args.reboot_ec,
         hash: args.hash.map(|x| x.into_os_string().into_string().unwrap()),

framework_lib/src/commandline/mod.rs

@@ -181,6 +181,7 @@ pub struct Cli {
     pub rgbkbd: Vec<u64>,
     pub tablet_mode: Option<TabletModeArg>,
     pub touchscreen_enable: Option<bool>,
+    pub stylus_battery: bool,
     pub console: Option<ConsoleArg>,
     pub reboot_ec: Option<RebootEcArg>,
     pub hash: Option<String>,
@@ -333,6 +334,18 @@ fn active_mode(mode: &FwMode, reference: FwMode) -> &'static str {
     }
 }
 
+#[cfg(feature = "hidapi")]
+fn print_stylus_battery_level() {
+    loop {
+        if let Some(level) = touchscreen::get_battery_level() {
+            println!("Stylus Battery Strength: {}%", level);
+            return;
+        } else {
+            debug!("Stylus Battery Strength: Unknown");
+        }
+    }
+}
+
 fn print_versions(ec: &CrosEc) {
     println!("UEFI BIOS");
     if let Some(smbios) = get_smbios() {
@@ -811,6 +824,11 @@ pub fn run_with_args(args: &Cli, _allupdate: bool) -> i32 {
         if touchscreen::enable_touch(*_enable).is_none() {
             error!("Failed to enable/disable touch");
         }
+    } else if args.stylus_battery {
+        #[cfg(feature = "hidapi")]
+        print_stylus_battery_level();
+        #[cfg(not(feature = "hidapi"))]
+        error!("Not build with hidapi feature");
     } else if let Some(console_arg) = &args.console {
         match console_arg {
             ConsoleArg::Follow => {

framework_lib/src/commandline/uefi.rs

@@ -94,6 +94,7 @@ pub fn parse(args: &[String]) -> Cli {
         rgbkbd: vec![],
         tablet_mode: None,
         touchscreen_enable: None,
+        stylus_battery: false,
         console: None,
         reboot_ec: None,
         hash: None,

framework_lib/src/touchscreen.rs

@@ -110,6 +110,35 @@ impl TouchScreen for HidapiTouchScreen {
         Some(buf[msg_len..msg_len + read_len].to_vec())
     }
 
+    fn get_battery_status(&self) -> Option<u8> {
+        let mut msg = [0u8; 0x40];
+        msg[0] = 0x0D;
+        self.device.read(&mut msg).ok()?;
+        // println!("  Tip Switch        {}%", msg[12]);
+        // println!("  Barrell Switch:   {}%", msg[12]);
+        // println!("  Eraser:           {}%", msg[12]);
+        // println!("  Invert:           {}%", msg[12]);
+        // println!("  In Range:         {}%", msg[12]);
+        // println!("  2nd Barrel Switch:{}%", msg[12]);
+        // println!("  X                 {}%", msg[12]);
+        // println!("  Y                 {}%", msg[12]);
+        // println!("  Tip Pressure:     {}%", msg[12]);
+        // println!("  X Tilt:           {}%", msg[12]);
+        // println!("  Y Tilt:           {}%", msg[12]);
+        debug!("  Battery Strength: {}%", msg[12]);
+        debug!(
+            "  Barrel Pressure:  {}",
+            u16::from_le_bytes([msg[13], msg[14]])
+        );
+        debug!("  Transducer Index: {}", msg[15]);
+
+        if msg[12] == 0 {
+            None
+        } else {
+            Some(msg[12])
+        }
+    }
+
     fn get_stylus_fw(&self) -> Option<()> {
         let mut msg = [0u8; 0x40];
         msg[0] = REPORT_ID_USI_VER;
@@ -190,6 +219,18 @@ pub trait TouchScreen {
     }
 
     fn get_stylus_fw(&self) -> Option<()>;
+    fn get_battery_status(&self) -> Option<u8>;
+}
+
+pub fn get_battery_level() -> Option<u8> {
+    for skip in 0..5 {
+        if let Some(device) = HidapiTouchScreen::open_device(0x000D, skip) {
+            if let Some(level) = device.get_battery_status() {
+                return Some(level);
+            }
+        }
+    }
+    None
 }
 
 pub fn print_fw_ver() -> Option<()> {