feat: Add serial logging (#3)

Reviewed-on: #3

kernel/src/logger/logger.rs

@@ -11,6 +11,7 @@ static LOGGER: OnceCell<LockedLogger> = OnceCell::uninit();
 /// A logger instance protected by a spinlock.
 struct LockedLogger {
     framebuffer: Option<Spinlock<framebuffer::FrameBufferWriter>>,
+    serial: Option<Spinlock<serial::SerialPort>>
 }
 
 impl LockedLogger {
@@ -20,9 +21,11 @@ impl LockedLogger {
         info: FrameBufferInfo,
     ) -> Self {
         let framebuffer = Some(Spinlock::new(framebuffer::FrameBufferWriter::new(framebuffer, info)));
+        let serial = Some(Spinlock::new(unsafe { serial::SerialPort::init() }));
 
         LockedLogger {
             framebuffer,
+            serial
         }
     }
 
@@ -34,6 +37,10 @@ impl LockedLogger {
         if let Some(framebuffer) = &self.framebuffer {
             unsafe { framebuffer.force_unlock() };
         }
+
+        if let Some(serial) = &self.serial {
+            unsafe { serial.force_unlock() };
+        }
     }
 }
 
@@ -47,6 +54,11 @@ impl log::Log for LockedLogger {
             let mut framebuffer = framebuffer.lock();
             writeln!(framebuffer, "{:5}: {}", record.level(), record.args()).unwrap();
         }
+
+        if let Some(serial) = &self.serial {
+            let mut serial = serial.lock();
+            writeln!(serial, "{:5}: {}", record.level(), record.args()).unwrap();
+        }
     }
 
     fn flush(&self) {}

kernel/src/logger/mod.rs

@@ -1,4 +1,5 @@
 pub mod logger;
 mod framebuffer;
+mod serial;
 
 pub use logger::*;

kernel/src/logger/serial.rs

@@ -0,0 +1,28 @@
+use core::fmt;
+
+pub struct SerialPort {
+    port: uart_16550::SerialPort,
+}
+
+impl SerialPort {
+    /// # Safety
+    ///
+    /// unsafe because this function must only be called once
+    pub unsafe fn init() -> Self {
+        let mut port = unsafe { uart_16550::SerialPort::new(0x3F8) };
+        port.init();
+        Self { port }
+    }
+}
+
+impl fmt::Write for SerialPort {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for char in s.bytes() {
+            match char {
+                b'\n' => self.port.write_str("\r\n").unwrap(),
+                byte => self.port.send(byte),
+            }
+        }
+        Ok(())
+    }
+}

kernel/src/main.rs

@@ -23,6 +23,8 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
     logger::init_logger(buffer, info);
 
     log::info!("Hello World from KERNEL");
+
+    // Endless loop as the kernel must stay running
     loop {}
 }