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use core::fmt;
use crate::LineStsFlags;
/// A x86 I/O port-mapped UART.
#[cfg_attr(docsrs, doc(cfg(any(target_arch = "x86", target_arch = "x86_64"))))]
#[derive(Debug)]
pub struct SerialPort(u16 /* base port */);
impl SerialPort {
/// Base port.
fn port_base(&self) -> u16 {
self.0
}
/// Data port.
///
/// Read and write.
fn port_data(&self) -> u16 {
self.port_base()
}
/// Interrupt enable port.
///
/// Write only.
fn port_int_en(&self) -> u16 {
self.port_base() + 1
}
/// Fifo control port.
///
/// Write only.
fn port_fifo_ctrl(&self) -> u16 {
self.port_base() + 2
}
/// Line control port.
///
/// Write only.
fn port_line_ctrl(&self) -> u16 {
self.port_base() + 3
}
/// Modem control port.
///
/// Write only.
fn port_modem_ctrl(&self) -> u16 {
self.port_base() + 4
}
/// Line status port.
///
/// Read only.
fn port_line_sts(&self) -> u16 {
self.port_base() + 5
}
/// Creates a new serial port interface on the given I/O base port.
///
/// This function is unsafe because the caller must ensure that the given base address
/// really points to a serial port device and that the caller has the necessary rights
/// to perform the I/O operation.
pub const unsafe fn new(base: u16) -> Self {
Self(base)
}
/// Initializes the serial port.
///
/// The default configuration of [38400/8-N-1](https://en.wikipedia.org/wiki/8-N-1) is used.
pub fn init(&mut self) {
unsafe {
// Disable interrupts
x86::io::outb(self.port_int_en(), 0x00);
// Enable DLAB
x86::io::outb(self.port_line_ctrl(), 0x80);
// Set maximum speed to 38400 bps by configuring DLL and DLM
x86::io::outb(self.port_data(), 0x03);
x86::io::outb(self.port_int_en(), 0x00);
// Disable DLAB and set data word length to 8 bits
x86::io::outb(self.port_line_ctrl(), 0x03);
// Enable FIFO, clear TX/RX queues and
// set interrupt watermark at 14 bytes
x86::io::outb(self.port_fifo_ctrl(), 0xc7);
// Mark data terminal ready, signal request to send
// and enable auxilliary output #2 (used as interrupt line for CPU)
x86::io::outb(self.port_modem_ctrl(), 0x0b);
// Enable interrupts
x86::io::outb(self.port_int_en(), 0x01);
}
}
fn line_sts(&mut self) -> LineStsFlags {
unsafe { LineStsFlags::from_bits_truncate(x86::io::inb(self.port_line_sts())) }
}
/// Sends a byte on the serial port.
pub fn send(&mut self, data: u8) {
unsafe {
match data {
8 | 0x7F => {
wait_for!(self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY));
x86::io::outb(self.port_data(), 8);
wait_for!(self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY));
x86::io::outb(self.port_data(), b' ');
wait_for!(self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY));
x86::io::outb(self.port_data(), 8);
}
_ => {
wait_for!(self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY));
x86::io::outb(self.port_data(), data);
}
}
}
}
/// Sends a raw byte on the serial port, intended for binary data.
pub fn send_raw(&mut self, data: u8) {
unsafe {
wait_for!(self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY));
x86::io::outb(self.port_data(), data);
}
}
/// Receives a byte on the serial port.
pub fn receive(&mut self) -> u8 {
unsafe {
wait_for!(self.line_sts().contains(LineStsFlags::INPUT_FULL));
x86::io::inb(self.port_data())
}
}
}
impl fmt::Write for SerialPort {
fn write_str(&mut self, s: &str) -> fmt::Result {
for byte in s.bytes() {
self.send(byte);
}
Ok(())
}
}