x86: make com-port usable as a serial console

kernel/src/arch/i686/mod.rs

@@ -5,6 +5,7 @@ use abi::error::Error;
 use alloc::sync::Arc;
 use boot::multiboot::MultibootInfo;
 use device_api::{
+    device::Device,
     interrupt::{IpiDeliveryTarget, IpiMessage, Irq},
     ResetDevice,
 };
@@ -159,14 +160,9 @@ impl I686 {
         phys::init_from_iter(multiboot_info.memory_map_iter(), |_, _, _| Ok(()))?;
 
         debug::init();
+        devfs::init();
 
-        let com1_3 = Arc::new(ComPort::new(
-            0x3F8,
-            0x3E8,
-            Irq::External(ISA_IRQ_OFFSET + 4),
-        ));
-
-        debug::add_sink(com1_3.port_a().clone(), LogLevel::Debug);
+        let com1_3 = ComPort::setup(0x3F8, 0x3E8, Irq::External(ISA_IRQ_OFFSET + 4))?;
 
         unsafe { init_gdt() };
         unsafe { exception::init_exceptions() };
@@ -190,7 +186,6 @@ impl I686 {
         Cpu::init_local(Some(0), cpu_data);
 
         runtime::init_task_queue();
-        devfs::init();
 
         // Register the PCI drivers
         //  TODO make this implicit init
@@ -243,6 +238,9 @@ impl I686 {
         if let Err(error) = Rtc::setup() {
             log::error!("RTC init error: {error:?}");
         }
+        if let Err(error) = unsafe { com1_3.port_a().clone().init_irq() } {
+            log::error!("COM port IRQ init error: {error:?}");
+        }
 
         // Setup text framebuffer
         // TODO check if video mode is set from boot info

kernel/src/arch/x86/intrinsics.rs

@@ -16,6 +16,10 @@ pub trait IoPortAccess<T> {
     fn read(&self) -> T;
     /// Writes a value to the port
     fn write(&self, value: T);
+
+    fn modify<F: FnOnce(T) -> T>(&self, f: F) {
+        self.write(f(self.read()));
+    }
 }
 
 impl<T> IoPort<T> {

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

@@ -1,21 +1,35 @@
 //! Driver for x86 COM ports
-use abi::error::Error;
+use abi::{error::Error, io::TerminalOptions};
 use alloc::sync::Arc;
-use device_api::{device::Device, interrupt::Irq, serial::SerialDevice};
-use libk::debug::DebugSink;
+use device_api::{
+    device::Device,
+    interrupt::{InterruptHandler, Irq},
+};
+use libk::{
+    debug::{DebugSink, LogLevel},
+    device::{external_interrupt_controller, manager::DEVICE_REGISTRY},
+    vfs::{Terminal, TerminalInput, TerminalOutput},
+};
 use libk_util::sync::IrqSafeSpinlock;
 
 use crate::arch::x86::intrinsics::{IoPort, IoPortAccess};
 
 // Single port
-struct Inner {
+struct Regs {
     dr: IoPort<u8>,
     lsr: IoPort<u8>,
+    ier: IoPort<u8>,
+    isr: IoPort<u8>,
+}
+
+struct PortInner {
+    regs: IrqSafeSpinlock<Regs>,
 }
 
 /// Single port of the COM port pair
 pub struct Port {
-    inner: IrqSafeSpinlock<Inner>,
+    terminal: Arc<Terminal<PortInner>>,
+    irq: Irq,
 }
 
 /// COM port pair
@@ -23,28 +37,9 @@ pub struct Port {
 pub struct ComPort {
     port_a: Arc<Port>,
     port_b: Arc<Port>,
-    irq: Irq,
 }
 
-impl DebugSink for Port {
-    fn putc(&self, c: u8) -> Result<(), Error> {
-        self.send_byte(c)
-    }
-
-    fn puts(&self, s: &str) -> Result<(), Error> {
-        let mut inner = self.inner.lock();
-        for b in s.bytes() {
-            inner.write(b)?;
-        }
-        Ok(())
-    }
-
-    fn supports_control_sequences(&self) -> bool {
-        true
-    }
-}
-
-impl Inner {
+impl Regs {
     fn write(&mut self, byte: u8) -> Result<(), Error> {
         while self.lsr.read() & Port::LSR_THRE == 0 {
             core::hint::spin_loop();
@@ -55,48 +50,144 @@ impl Inner {
     }
 }
 
-impl SerialDevice for Port {
-    fn send_byte(&self, byte: u8) -> Result<(), Error> {
-        let mut inner = self.inner.lock();
-        inner.write(byte)
+impl PortInner {
+    fn handle_irq(&self) -> Option<u8> {
+        let (status, value) = {
+            let inner = self.regs.lock();
+            let status = inner.isr.read();
+            let value = inner.dr.read();
+            (status, value)
+        };
+
+        if status & Port::ISR_IRQ_MASK != 0 {
+            Some(value)
+        } else {
+            None
+        }
+    }
 }
 
-    fn is_terminal(&self) -> bool {
+impl TerminalOutput for PortInner {
+    fn write(&self, byte: u8) -> Result<(), Error> {
+        self.regs.lock().write(byte)
+    }
+
+    fn write_multiple(&self, bytes: &[u8]) -> Result<usize, Error> {
+        let mut regs = self.regs.lock();
+        for &b in bytes {
+            regs.write(b)?;
+        }
+        Ok(bytes.len())
+    }
+}
+
+impl DebugSink for Port {
+    fn putc(&self, c: u8) -> Result<(), Error> {
+        self.terminal.putc_to_output(c).ok();
+        Ok(())
+    }
+
+    fn puts(&self, s: &str) -> Result<(), Error> {
+        self.terminal.write_to_output(s.as_bytes()).ok();
+        Ok(())
+    }
+
+    fn supports_control_sequences(&self) -> bool {
+        true
+    }
+}
+
+// impl SerialDevice for Port {
+//     fn send_byte(&self, byte: u8) -> Result<(), Error> {
+//         let mut inner = self.inner.lock();
+//         inner.write(byte)
+//     }
+//
+//     fn is_terminal(&self) -> bool {
+//         false
+//     }
+// }
+
+impl InterruptHandler for Port {
+    fn handle_irq(self: Arc<Self>, _vector: Option<usize>) -> bool {
+        let inner = self.terminal.output();
+        if let Some(byte) = inner.handle_irq() {
+            self.terminal.write_to_input(byte);
+            true
+        } else {
             false
         }
     }
 
+    fn display_name(&self) -> &str {
+        "x86 COM port IRQ"
+    }
+}
+
 impl Device for Port {
     fn display_name(&self) -> &'static str {
         "COM port"
     }
 
     unsafe fn init(self: Arc<Self>) -> Result<(), Error> {
+        DEVICE_REGISTRY
+            .serial_terminal
+            .register(self.terminal.clone(), Some((self.clone(), LogLevel::Debug)))
+            .ok();
+        Ok(())
+    }
+
+    unsafe fn init_irq(self: Arc<Self>) -> Result<(), Error> {
+        let intc = external_interrupt_controller()?;
+
+        // TODO check that the same IRQ is not bound already for another port
+        intc.register_irq(self.irq, Default::default(), self.clone())?;
+        intc.enable_irq(self.irq)?;
+
+        let regs = self.terminal.output().regs.lock();
+
+        regs.ier.modify(|v| v | Self::IER_RXDA);
+
         Ok(())
     }
 }
 
 impl Port {
     const LSR_THRE: u8 = 1 << 5;
+    const IER_RXDA: u8 = 1 << 0;
+    const ISR_IRQ_MASK: u8 = 3 << 1;
 
-    const fn new(base: u16) -> Self {
-        Self {
-            inner: IrqSafeSpinlock::new(Inner {
+    fn new(base: u16, irq: Irq) -> Result<Self, Error> {
+        let input = TerminalInput::with_capacity(64)?;
+        let output = PortInner {
+            regs: IrqSafeSpinlock::new(Regs {
                 dr: IoPort::new(base),
                 lsr: IoPort::new(base + 5),
+                ier: IoPort::new(base + 1),
+                isr: IoPort::new(base + 2),
             }),
-        }
+        };
+        let terminal = Terminal::from_parts(TerminalOptions::const_default(), input, output);
+        Ok(Self {
+            terminal: Arc::new(terminal),
+            irq,
+        })
     }
 }
 
 impl ComPort {
     /// Constructs a COM port pair
-    pub fn new(port_a: u16, port_b: u16, irq: Irq) -> Self {
-        Self {
-            port_a: Arc::new(Port::new(port_a)),
-            port_b: Arc::new(Port::new(port_b)),
-            irq,
+    fn new(port_a: u16, port_b: u16, irq: Irq) -> Result<Self, Error> {
+        Ok(Self {
+            port_a: Arc::new(Port::new(port_a, irq)?),
+            port_b: Arc::new(Port::new(port_b, irq)?),
+        })
     }
+
+    pub fn setup(port_a: u16, port_b: u16, irq: Irq) -> Result<Arc<Self>, Error> {
+        let this = Arc::new(Self::new(port_a, port_b, irq)?);
+        unsafe { this.port_a().clone().init() }?;
+        Ok(this)
     }
 
     /// Returns a reference to the A port of this COM pair

kernel/src/arch/x86_64/mod.rs

@@ -6,7 +6,7 @@ use abi::error::Error;
 use acpi::{AcpiAllocator, AcpiHandlerImpl};
 use alloc::{boxed::Box, sync::Arc};
 use apic::{ioapic::IoApic, local::LocalApic};
-use device_api::interrupt::Irq;
+use device_api::{device::Device, interrupt::Irq};
 use git_version::git_version;
 use kernel_arch_x86::{
     cpuid::{self, CpuFeatures, EcxFeatures, EdxFeatures},
@@ -336,13 +336,7 @@ impl X86_64 {
 
             debug::init();
 
-            let com1_3 = Arc::new(ComPort::new(
-                0x3F8,
-                0x3E8,
-                Irq::External(ISA_IRQ_OFFSET + 4),
-            ));
-
-            debug::add_sink(com1_3.port_a().clone(), LogLevel::Debug);
+            let com1_3 = ComPort::setup(0x3F8, 0x3E8, Irq::External(ISA_IRQ_OFFSET + 4))?;
             // TODO register platform devices
 
             DEVICE_REGISTRY.display.set_callback(|device, node| {
@@ -391,6 +385,9 @@ impl X86_64 {
             if let Err(error) = Rtc::setup() {
                 log::error!("RTC init error: {error:?}");
             }
+            if let Err(error) = unsafe { com1_3.port_a().clone().init_irq() } {
+                log::error!("COM port IRQ init error: {error:?}");
+            }
 
             PciBusManager::setup_bus_devices()?;
         }

userspace/arch/i686/inittab

@@ -2,3 +2,4 @@ init:1:wait:/sbin/rc default
 logd:1:once:/sbin/logd
 
 user:1:once:/sbin/login /dev/tty0
+user:1:once:/sbin/login /dev/ttyS0

userspace/arch/x86_64/inittab

@@ -1,2 +1,4 @@
 init:1:wait:/sbin/rc default
 logd:1:once:/sbin/logd
+
+user:1:once:/sbin/login /dev/ttyS0