Switch to uart2 on malta to get interrupts (not working)

Signed-off-by: Harry Chen <i@harrychen.xyz>

kernel/Makefile

@@ -134,7 +134,13 @@ qemu_opts += \
 	-kernel $(kernel_img)
 
 else ifeq ($(arch), mipsel)
-ifeq ($(board), $(filter $(board), malta mipssim))
+ifeq ($(board), malta)
+qemu_opts += \
+	-machine $(board) \
+	-serial null -serial null -serial mon:stdio \
+	-kernel $(kernel_img)
+endif
+ifeq ($(board), mipssim)
 qemu_opts += \
 	-machine $(board) \
 	-serial mon:stdio \

kernel/src/arch/mipsel/board/malta/mod.rs

@@ -1,5 +1,6 @@
 use once::*;
 use alloc::string::String;
+use mips::registers::cp0;
 
 #[path = "../../../../drivers/serial/16550_reg.rs"]
 pub mod serial;
@@ -12,7 +13,14 @@ pub mod consts;
 /// Initialize serial port first
 pub fn init_serial_early() {
     assert_has_not_been_called!("board::init must be called only once");
-    serial::init(0xb80003f8);
+    // initialize serial driver
+    serial::init(0xbf000900);
+    // Enable serial interrupt
+    unsafe {
+        let mut status = cp0::status::read();
+        status.enable_hard_int2();
+        cp0::status::write(status);
+    }
     println!("Hello QEMU Malta!");
 }
 

kernel/src/arch/mipsel/interrupt.rs

@@ -75,7 +75,7 @@ pub extern fn rust_trap(tf: &mut TrapFrame) {
 
 fn interrupt_dispatcher(tf: &mut TrapFrame) {
     let pint = tf.cause.pending_interrupt();
-    trace!("  Interrupt {:?} ", tf.cause.pending_interrupt());
+    trace!("  Interrupt {:08b} ", pint);
     if (pint & 0b100_000_00) != 0 {
         timer();
     } else if (pint & 0b011_111_00) != 0 {
@@ -86,7 +86,6 @@ fn interrupt_dispatcher(tf: &mut TrapFrame) {
 }
 
 fn external() {
-    // TODO
     // true means handled, false otherwise
     let handlers = [try_process_serial, try_process_drivers];
     for handler in handlers.iter() {
@@ -99,6 +98,7 @@ fn external() {
 fn try_process_serial() -> bool {
     match super::io::getchar_option() {
         Some(ch) => {
+            trace!("Get char {} from serial", ch);
             crate::trap::serial(ch);
             true
         }