From a10a7cafa10eb873680b30f7fb201ae4ac131c2b Mon Sep 17 00:00:00 2001
From: Yuhao Zhou <miskcoo@gmail.com>
Date: Fri, 5 Apr 2019 21:18:24 +0800
Subject: [PATCH] Add interrupt dispatcher.

---
 kernel/src/arch/mipsel/context.rs   |  4 +-
 kernel/src/arch/mipsel/cpu.rs       | 18 ++-----
 kernel/src/arch/mipsel/interrupt.rs | 73 ++++++++++++++++-------------
 3 files changed, 47 insertions(+), 48 deletions(-)

diff --git a/kernel/src/arch/mipsel/context.rs b/kernel/src/arch/mipsel/context.rs
index 09514c4..c968874 100644
--- a/kernel/src/arch/mipsel/context.rs
+++ b/kernel/src/arch/mipsel/context.rs
@@ -92,9 +92,9 @@ impl Debug for TrapFrame {
     fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
         f.debug_struct("TrapFrame")
             .field("status", &self.status.bits)
-            .field("epc", &self.epc.bits)
+            .field("epc", &self.epc)
             .field("cause", &self.cause.bits)
-            .field("vaddr", &self.vaddr.bits)
+            .field("vaddr", &self.vaddr)
             .finish()
     }
 }
diff --git a/kernel/src/arch/mipsel/cpu.rs b/kernel/src/arch/mipsel/cpu.rs
index dea1df9..ea27d1f 100644
--- a/kernel/src/arch/mipsel/cpu.rs
+++ b/kernel/src/arch/mipsel/cpu.rs
@@ -1,20 +1,11 @@
+use mips::registers::cp0;
 use crate::consts::MAX_CPU_NUM;
 use core::ptr::{read_volatile, write_volatile};
 
 static mut STARTED: [bool; MAX_CPU_NUM] = [false; MAX_CPU_NUM];
 
-pub unsafe fn set_cpu_id(cpu_id: usize) {
-    asm!("mv gp, $0" : : "r"(cpu_id));
-}
-
 pub fn id() -> usize {
-    let cpu_id;
-    unsafe { asm!("mv $0, gp" : "=r"(cpu_id)); }
-    cpu_id
-}
-
-pub fn send_ipi(cpu_id: usize) {
-    super::sbi::send_ipi(1 << cpu_id);
+    (cp0::ebase::read_u32() as usize) & 0x3ff
 }
 
 pub unsafe fn has_started(cpu_id: usize) -> bool {
@@ -30,9 +21,10 @@ pub unsafe fn start_others(hart_mask: usize) {
 }
 
 pub fn halt() {
-    unsafe { riscv::asm::wfi() }
+    /* nothing to do */
 }
 
 pub unsafe fn exit_in_qemu(error_code: u8) -> ! {
-    super::sbi::shutdown()
+    /* nothing to do */
+    loop {}
 }
diff --git a/kernel/src/arch/mipsel/interrupt.rs b/kernel/src/arch/mipsel/interrupt.rs
index 12fda2e..22f23ce 100644
--- a/kernel/src/arch/mipsel/interrupt.rs
+++ b/kernel/src/arch/mipsel/interrupt.rs
@@ -9,24 +9,23 @@ mod context;
 
 /// Initialize interrupt
 pub fn init() {
-    // TODO
- //   extern {
- //       fn trap_entry();
- //   }
- //   unsafe {
- //       // Set sscratch register to 0, indicating to exception vector that we are
- //       // presently executing in the kernel
- //       sscratch::write(0);
- //       // Set the exception vector address
- //       stvec::write(trap_entry as usize, stvec::TrapMode::Direct);
- //       // Enable IPI
- //       sie::set_ssoft();
- //       // Enable external interrupt
- //       if super::cpu::id() == super::BOOT_HART_ID {
- //           sie::set_sext();
- //       }
- //   }
- //   info!("interrupt: init end");
+    extern {
+        fn trap_entry();
+    }
+    unsafe {
+        // Set the exception vector address
+        cp0::ebase::write_u32(trap_entry as u32);
+
+        let mut status = cp0::status::read();
+        // Enable IPI
+        status.enable_soft_int0();
+        status.enable_soft_int1();
+        // Enable clock interrupt
+        status.enable_hard_int5();
+
+        cp0::status::write(status);
+    }
+    info!("interrupt: init end");
 }
 
 /// Enable interrupt
@@ -56,22 +55,30 @@ pub unsafe fn restore(flags: usize) {
 /// This function is called from `trap.asm`.
 #[no_mangle]
 pub extern fn rust_trap(tf: &mut TrapFrame) {
-    // TODO
-    use self::scause::{Trap, Interrupt as I, Exception as E};
-    // trace!("Interrupt @ CPU{}: {:?} ", super::cpu::id(), tf.scause.cause());
-    match tf.scause.cause() {
-        Trap::Interrupt(I::SupervisorExternal) => external(),
-        Trap::Interrupt(I::SupervisorSoft) => ipi(),
-        Trap::Interrupt(I::SupervisorTimer) => timer(),
-        Trap::Exception(E::UserEnvCall) => syscall(tf),
-        Trap::Exception(E::LoadPageFault) => page_fault(tf),
-        Trap::Exception(E::StorePageFault) => page_fault(tf),
-        Trap::Exception(E::InstructionPageFault) => page_fault(tf),
+    use cp0::cause::{Exception as E};
+    trace!("Interrupt @ CPU{}: {:?} ", 0, tf.cause.cause());
+    match tf.cause.cause() {
+        E::Interrupt => interrupt_dispatcher(),
+        E::Syscall => syscall(tf),
+        E::TLBModification => page_fault(tf),
+        E::TLBLoadMiss => page_fault(tf),
+        E::TLBStoreMiss => page_fault(tf),
         _ => crate::trap::error(tf),
     }
     trace!("Interrupt end");
 }
 
+fn interrupt_dispatcher(tf: &mut TrapFrame) {
+    let pint = tf.cause.pending_interrupt();
+    if (pint & 0b10000_00) != 0 {
+        timer();
+    } else if (pint & 0xb01111_00) != 0 {
+        external();
+    } else {
+        ipi();
+    }
+}
+
 fn external() {
     // TODO
     // true means handled, false otherwise
@@ -104,7 +111,7 @@ fn try_process_drivers() -> bool {
 }
 
 fn ipi() {
-    // TODO
+    /* do nothing */
     debug!("IPI");
 //    super::sbi::clear_ipi();
 }
@@ -115,14 +122,14 @@ fn timer() {
 }
 
 fn syscall(tf: &mut TrapFrame) {
-    tf.sepc += 4;   // Must before syscall, because of fork.
+    tf.epc += 4;   // Must before syscall, because of fork.
     let ret = crate::syscall::syscall(tf.t0, [tf.t0, tf.t1, tf.t2, tf.t3, tf.s0, tf.s1], tf);
     tf.v0 = ret as usize;
 }
 
 fn page_fault(tf: &mut TrapFrame) {
-    // TODO
-    let addr = tf.stval;
+    // TODO: set access/dirty bit
+    let addr = tf.vaddr;
     trace!("\nEXCEPTION: Page Fault @ {:#x}", addr);
 
     if !crate::memory::handle_page_fault(addr) {