aarch64: implement I/O by serial port

kernel/src/arch/aarch64/board/raspi3/mod.rs

@@ -2,8 +2,12 @@
 
 extern crate bcm2837;
 
+pub mod serial;
+
 pub fn init() {
-    // TODO
-    bcm2837::gpio::Gpio::new(14).set_gpio_pd(0);
-    bcm2837::gpio::Gpio::new(15).set_gpio_pd(0);
+    assert_has_not_been_called!("board::init must be called only once");
+
+    serial::SERIAL_PORT.lock().init();
+
+    println!("Hello Raspberry Pi!");
 }

kernel/src/arch/aarch64/board/raspi3/serial.rs

@@ -0,0 +1,73 @@
+use super::bcm2837::mini_uart::MiniUart;
+
+use core::fmt;
+use spin::Mutex;
+
+/// Struct to get a global SerialPort interface
+pub struct SerialPort {
+    mu: Option<MiniUart>,
+}
+
+pub trait SerialRead {
+    fn receive(&mut self) -> u8;
+}
+
+impl SerialPort {
+    /// Creates a new instance of `SerialPort`.
+    const fn new() -> SerialPort {
+        SerialPort { mu: None }
+    }
+
+    /// Init a newly created SerialPort, can only be called once.
+    pub fn init(&mut self) {
+        assert_has_not_been_called!("SerialPort::init must be called only once");
+        self.mu = Some(MiniUart::new());
+    }
+
+    /// Writes the byte `byte` to the UART device.
+    pub fn write_byte(&mut self, byte: u8) {
+        match &mut self.mu {
+            Some(mu) => mu.write_byte(byte),
+            None => panic!("SerialPort is not initialized"),
+        }
+    }
+
+    /// Reads a byte from the UART device, blocking until a byte is available.
+    pub fn read_byte(&mut self) -> u8 {
+        match &mut self.mu {
+            Some(mu) => return mu.read_byte(),
+            None => panic!("SerialPort is not initialized"),
+        }
+    }
+}
+
+impl SerialRead for SerialPort {
+    fn receive(&mut self) -> u8 {
+        self.read_byte()
+    }
+}
+
+impl fmt::Write for SerialPort {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for byte in s.bytes() {
+            match byte {
+                // Backspace
+                b'\x7f' => {
+                    self.write_byte(b'\x08');
+                    self.write_byte(b' ');
+                    self.write_byte(b'\x08');
+                }
+                // Return
+                b'\n' => {
+                    self.write_byte(b'\r');
+                    self.write_byte(b'\n');
+                }
+                // Others
+                _ => self.write_byte(byte),
+            }
+        }
+        Ok(())
+    }
+}
+
+pub static SERIAL_PORT: Mutex<SerialPort> = Mutex::new(SerialPort::new());

kernel/src/arch/aarch64/boot/boot.S

@@ -55,6 +55,15 @@ switch_to_el1:
     movk    x0, #0x8000, lsl #16
     msr     hcr_el2, x0
 
+
+    # don't trap accessing SVE registers (ref: D10.2.30)
+    msr     cptr_el2, xzr
+
+    # enable floating point and SVE (SIMD) (bits 20, 21) (ref: D10.2.29)
+    mrs     x0, cpacr_el1
+    orr     x0, x0, #(0x3 << 20)
+    msr     cpacr_el1, x0
+
     # Set SCTLR to known state (RES1: 11, 20, 22, 23, 28, 29) (ref: D10.2.100)
     mov     x0, #0x0800
     movk    x0, #0x30d0, lsl #16

kernel/src/arch/aarch64/io.rs

@@ -1,13 +1,12 @@
 //! Serial driver for aarch64.
 
-use core::fmt::{Arguments};
+use core::fmt::{Arguments, Write};
+use super::board::serial::{SerialRead, SERIAL_PORT};
 
-/// TODO
 pub fn getchar() -> char {
-    unimplemented!()
+    SERIAL_PORT.lock().receive() as char
 }
 
-/// TODO
-pub fn putfmt(fmt: Arguments<'_>) {
-    unimplemented!()
+pub fn putfmt(fmt: Arguments) {
+    SERIAL_PORT.lock().write_fmt(fmt).unwrap()
 }

kernel/src/arch/aarch64/mod.rs

@@ -13,21 +13,33 @@ pub mod board;
 /// The entry point of kernel
 #[no_mangle] // don't mangle the name of this function
 pub extern "C" fn rust_main() -> ! {
-    // Init board.
+    // Init board to enable serial port.
     board::init();
 
-    println!("Hello ARM64!");
-
     // First init log mod, so that we can print log info.
-    // ::logging::init();
-    // Init trap handling.
-    // interrupt::init();
-    // Init physical memory management and heap.
-    // memory::init();
-    // Now heap is available
-    // timer::init();
+    ::logging::init();
+
+    loop {
+        print!(">> ");
+        loop {
+            let c = io::getchar();
+            match c {
+                '\u{7f}' => {
+                    print!("\u{7f}");
+                }
+                ' '...'\u{7e}' => {
+                    print!("{}", c);
+                }
+                '\n' | '\r' => {
+                    print!("\n");
+                    break;
+                }
+                _ => {}
+            }
+        }
+    }
 
-    ::kmain();
+    // ::kmain();
 }
 
 global_asm!(include_str!("boot/boot.S"));