sysutils: add serial console program

kernel/libk/src/vfs/terminal.rs

@@ -64,6 +64,20 @@ pub trait TerminalOutput: Sync + Send {
         }
         Ok(written)
     }
+
+    fn baud_rate(&self) -> u32 {
+        115200
+    }
+    fn set_baud_rate(&self, baud: u32) -> Result<(), Error> {
+        if baud == 115200 {
+            Ok(())
+        } else {
+            log::warn!(
+                "[this] TerminalOutput impl does not support baud rate changes (want {baud})"
+            );
+            Err(Error::NotImplemented)
+        }
+    }
 }
 
 struct InputBuffer {
@@ -72,7 +86,8 @@ struct InputBuffer {
 }
 
 impl<O: TerminalOutput> Terminal<O> {
-    pub fn from_parts(config: TerminalOptions, input: TerminalInput, output: O) -> Self {
+    pub fn from_parts(mut config: TerminalOptions, input: TerminalInput, output: O) -> Self {
+        config.baud_rate = output.baud_rate();
         Self {
             input,
             output,
@@ -212,7 +227,15 @@ impl<O: TerminalOutput> Terminal<O> {
             TerminalRequestVariant::SetTerminalOptions => {
                 let options = device::SetTerminalOptions::load_request(input)?;
                 self.input.flush();
-                *self.config.write() = options;
+                let need_baud_change = {
+                    let mut cfg = self.config.write();
+                    let need_baud_change = cfg.baud_rate != options.baud_rate;
+                    *cfg = options;
+                    need_baud_change
+                };
+                if need_baud_change {
+                    self.output.set_baud_rate(options.baud_rate)?;
+                }
                 device::SetTerminalOptions::store_response(&(), buffer)
             }
             TerminalRequestVariant::GetTerminalOptions => {

kernel/src/arch/x86/peripherals/serial.rs

@@ -17,8 +17,11 @@ use libk_util::sync::IrqSafeSpinlock;
 struct Regs {
     dr: IoPort<u8>,
     lsr: IoPort<u8>,
+    lcr: IoPort<u8>,
     ier: IoPort<u8>,
     isr: IoPort<u8>,
+
+    baud_rate: u32,
 }
 
 struct PortInner {
@@ -78,6 +81,30 @@ impl TerminalOutput for PortInner {
         }
         Ok(bytes.len())
     }
+
+    fn baud_rate(&self) -> u32 {
+        self.regs.lock().baud_rate
+    }
+
+    fn set_baud_rate(&self, baud: u32) -> Result<(), Error> {
+        if baud > 115200 {
+            log::warn!("Tried to set baud rate for COM port beyond 115200: {baud}");
+            return Err(Error::InvalidArgument);
+        }
+
+        let div = 115200 / baud;
+
+        let mut regs = self.regs.lock();
+
+        regs.lcr.write(regs.lcr.read() | (1 << 7));
+        regs.dr.write(div as u8);
+        regs.ier.write((div >> 8) as u8);
+        regs.lcr.write(regs.lcr.read() & !(1 << 7));
+
+        regs.baud_rate = baud;
+
+        Ok(())
+    }
 }
 
 impl DebugSink for Port {
@@ -114,6 +141,8 @@ impl Device for Port {
     }
 
     unsafe fn init(self: Arc<Self>, _cx: DeviceInitContext) -> Result<(), Error> {
+        self.terminal.output().set_baud_rate(115200)?;
+
         DEVICE_REGISTRY
             .serial_terminal
             .register(self.terminal.clone(), Some(self.clone()))
@@ -149,6 +178,9 @@ impl Port {
                 lsr: IoPort::new(base + 5),
                 ier: IoPort::new(base + 1),
                 isr: IoPort::new(base + 2),
+                lcr: IoPort::new(base + 3),
+
+                baud_rate: 0,
             }),
         };
         let terminal = Terminal::from_parts(TerminalOptions::const_default(), input, output);