aarch64: implement IRQ & system timer, but don't work in qemu

crate/bcm2837/src/interrupt.rs

@@ -0,0 +1,61 @@
+use super::IO_BASE;
+use volatile::{ReadOnly, Volatile};
+
+const INT_BASE: usize = IO_BASE + 0xB000 + 0x200;
+
+/// Allowed interrupts (ref: peripherals 7.5, page 113)
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub enum Interrupt {
+    Timer1 = 1,
+    Timer3 = 3,
+    Usb = 9,
+    Aux = 29,
+    Gpio0 = 49,
+    Gpio1 = 50,
+    Gpio2 = 51,
+    Gpio3 = 52,
+    Uart = 57,
+}
+
+/// Interrupts registers starting from `INT_BASE` (ref: peripherals 7.5, page 112)
+#[repr(C)]
+#[allow(non_snake_case)]
+struct Registers {
+    IRQBasicPending: ReadOnly<u32>,
+    IRQPending: [ReadOnly<u32>; 2],
+    FIQControl: Volatile<u32>,
+    EnableIRQ: [Volatile<u32>; 2],
+    EnableBasicIRQ: Volatile<u32>,
+    DisableIRQ: [Volatile<u32>; 2],
+    DisableBasicIRQ: Volatile<u32>,
+}
+
+/// An interrupt controller. Used to enable and disable interrupts as well as to
+/// check if an interrupt is pending.
+pub struct Controller {
+    registers: &'static mut Registers,
+}
+
+impl Controller {
+    /// Returns a new handle to the interrupt controller.
+    pub fn new() -> Controller {
+        Controller {
+            registers: unsafe { &mut *(INT_BASE as *mut Registers) },
+        }
+    }
+
+    /// Enables the interrupt `int`.
+    pub fn enable(&mut self, int: Interrupt) {
+        self.registers.EnableIRQ[int as usize / 32].write(1 << (int as usize) % 32);
+    }
+
+    /// Disables the interrupt `int`.
+    pub fn disable(&mut self, int: Interrupt) {
+        self.registers.DisableIRQ[int as usize / 32].write(1 << (int as usize) % 32);
+    }
+
+    /// Returns `true` if `int` is pending. Otherwise, returns `false`.
+    pub fn is_pending(&self, int: Interrupt) -> bool {
+        self.registers.IRQPending[int as usize / 32].read() & (1 << (int as usize) % 32) != 0
+    }
+}

crate/bcm2837/src/lib.rs

@@ -6,6 +6,8 @@ extern crate volatile;
 mod asm;
 
 pub mod gpio;
+pub mod timer;
 pub mod mini_uart;
+pub mod interrupt;
 
 pub const IO_BASE: usize = 0x3F000000;

crate/bcm2837/src/timer.rs

@@ -0,0 +1,68 @@
+use super::IO_BASE;
+use volatile::{ReadOnly, Volatile};
+
+/// The base address for the ARM system timer registers.
+const TIMER_REG_BASE: usize = IO_BASE + 0x3000;
+
+/// System timer registers (ref: peripherals 12.1, page 172)
+#[repr(C)]
+#[allow(non_snake_case)]
+struct Registers {
+    CS: Volatile<u32>,
+    CLO: ReadOnly<u32>,
+    CHI: ReadOnly<u32>,
+    COMPARE: [Volatile<u32>; 4],
+}
+
+#[repr(u8)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+pub enum SystemTimer {
+    Timer0 = 0,
+    Timer1 = 1,
+    Timer2 = 2,
+    Timer3 = 3,
+}
+
+/// The Raspberry Pi ARM system timer.
+pub struct Timer {
+    registers: &'static mut Registers,
+}
+
+impl Timer {
+    /// Returns a new instance of `Timer`.
+    pub fn new() -> Timer {
+        Timer {
+            registers: unsafe { &mut *(TIMER_REG_BASE as *mut Registers) },
+        }
+    }
+
+    /// Reads the system timer's counter and returns the 64-bit counter value.
+    /// The returned value is the number of elapsed microseconds.
+    pub fn read(&self) -> u64 {
+        let low = self.registers.CLO.read();
+        let high = self.registers.CHI.read();
+        ((high as u64) << 32) | (low as u64)
+    }
+
+    /// Sets up a match in timer 1 to occur `us` microseconds from now. If
+    /// interrupts for timer 1 are enabled and IRQs are unmasked, then a timer
+    /// interrupt will be issued in `us` microseconds.
+    pub fn tick_in(&mut self, st: SystemTimer, us: u32) {
+        let current_low = self.registers.CLO.read();
+        let compare = current_low.wrapping_add(us);
+        self.registers.COMPARE[st as usize].write(compare);
+        self.registers.CS.write(1 << (st as usize)); // unmask
+    }
+}
+
+/// Returns the current time in microseconds.
+pub fn current_time() -> u64 {
+    Timer::new().read()
+}
+
+/// Sets up a match in timer 1 to occur `us` microseconds from now. If
+/// interrupts for timer 1 are enabled and IRQs are unmasked, then a timer
+/// interrupt will be issued in `us` microseconds.
+pub fn tick_in(st: SystemTimer, us: u32) {
+    Timer::new().tick_in(st, us)
+}

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

@@ -0,0 +1,10 @@
+use super::bcm2837::interrupt::{Controller, Interrupt};
+
+pub fn handle_irq() {
+    let controller = Controller::new();
+    if controller.is_pending(Interrupt::Timer1) {
+        println!("Timer tick...");
+        super::timer::set_next();
+        // ::trap::timer();
+    }
+}

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

@@ -2,6 +2,8 @@
 
 extern crate bcm2837;
 
+pub mod irq;
+pub mod timer;
 pub mod serial;
 
 pub fn init() {

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

@@ -0,0 +1,16 @@
+use super::bcm2837::timer;
+use super::bcm2837::interrupt::{Controller, Interrupt};
+
+pub fn init() {
+    Controller::new().enable(Interrupt::Timer1);
+    set_next();
+}
+
+pub fn get_cycle() -> u64 {
+    timer::current_time()
+}
+
+pub fn set_next() {
+    // 1000 ms
+    timer::tick_in(timer::SystemTimer::Timer1, 1000 * 1000);
+}

kernel/src/arch/aarch64/interrupt/handler.rs

@@ -1,5 +1,6 @@
 //! Trap handler
 
+use arch::board::irq::handle_irq;
 use super::context::TrapFrame;
 use super::syndrome::Syndrome;
 
@@ -48,9 +49,7 @@ pub extern "C" fn rust_trap(info: Info, esr: u32, tf: &mut TrapFrame) {
                 _ => ::trap::error(tf),
             }
         }
-        Kind::Irq => {
-            // TODO
-        }
+        Kind::Irq => handle_irq(),
         _ => ::trap::error(tf),
     }
     ::trap::before_return();

kernel/src/arch/aarch64/interrupt/mod.rs

@@ -20,13 +20,13 @@ pub fn init() {
 /// Enable the interrupt.
 #[inline(always)]
 pub unsafe fn enable() {
-    // TODO
+    asm!("msr daifclr, #2");
 }
 
 /// Disable the interrupt.
 #[inline(always)]
 pub unsafe fn disable() {
-    // TODO
+    asm!("msr daifset, #2");
 }
 
 /// Disable the interrupt and store the status.

kernel/src/arch/aarch64/mod.rs

@@ -9,6 +9,8 @@ pub mod interrupt;
 #[path = "board/raspi3/mod.rs"]
 pub mod board;
 
+pub use self::board::timer;
+
 /// TODO
 /// The entry point of kernel
 #[no_mangle] // don't mangle the name of this function
@@ -20,6 +22,9 @@ pub extern "C" fn rust_main() -> ! {
     // FIXME
     // ::logging::init();
     interrupt::init();
+    timer::init();
+
+    unsafe { interrupt::enable(); }
 
     super::fs::show_logo();
 
@@ -39,6 +44,9 @@ pub extern "C" fn rust_main() -> ! {
                     println!("svc 666");
                     asm!("svc 666");
                 },
+                't' => unsafe {
+                    println!("{}", timer::get_cycle());
+                },
                 ' '...'\u{7e}' => {
                     print!("{}", c);
                 }