Implement first basic interrupt handler

src/main.rs

@@ -2,20 +2,33 @@
 #![no_std]
 #![feature(asm_experimental_arch)]
 
-use core::{arch::asm, panic::PanicInfo};
+use core::{
+    arch::{asm, global_asm},
+    panic::PanicInfo,
+};
 
-use gpio::{gpio_get_state, gpio_high, gpio_low, gpio_pull_up, set_gpio_state};
+use gpio::{
+    gpio_enable_low_detect, gpio_get_state, gpio_high, gpio_low, gpio_pull_up, set_gpio_state,
+};
+use interrupt::enable_iqr_source;
 use timer::{delay_nops, sleep};
 use uart::print;
 
 mod gpio;
+mod interrupt;
 mod timer;
 mod uart;
 
+global_asm!(include_str!("vector.S"));
+
+extern "C" {
+    fn el2_to_el1();
+}
+
 #[panic_handler]
 fn panic(_panic: &PanicInfo) -> ! {
     loop {
-        uart::print("Panic");
+        uart::print("Panic\r\n");
     }
 }
 
@@ -23,13 +36,17 @@ fn panic(_panic: &PanicInfo) -> ! {
 #[link_section = ".text._start"]
 pub unsafe extern "C" fn _start() {
     // Set the stack pointer
-    asm!("ldr x0, =0x8004000", "mov sp, x0");
-    main();
+    asm!(
+        "ldr x0, =0x8008000",
+        "mov sp, x0",
+        "b main",
+        options(noreturn)
+    );
 }
 
 #[no_mangle]
-extern "C" fn main() {
-    uart::configure_uart();
+pub extern "C" fn main() -> ! {
+    uart::uart_init();
     // Set ACT Led to Outout
     let _ = set_gpio_state(21, gpio::GPIOState::Output);
 
@@ -37,16 +54,32 @@ extern "C" fn main() {
     let _ = set_gpio_state(14, gpio::GPIOState::Alternative0);
     let _ = set_gpio_state(15, gpio::GPIOState::Alternative0);
 
-    // Set GPIO 21 to Input
-    let _ = set_gpio_state(21, gpio::GPIOState::Input);
-    gpio_pull_up(21);
+    print_current_el_str();
 
     // Delay so clock speed can stabilize
     delay_nops(50000);
     uart::print("Hello World!\r\n");
 
+    unsafe {
+        el2_to_el1();
+    }
+
+    loop {}
+}
+
+#[no_mangle]
+pub extern "C" fn kernel_main() -> ! {
+    let el = get_current_el();
+    print_current_el_str();
+
     sleep(500_000);
 
+    // Set GPIO 21 to Input
+    enable_iqr_source(49); //21 is on the first GPIO bank
+    let _ = set_gpio_state(21, gpio::GPIOState::Input);
+    gpio_pull_up(21);
+    gpio_enable_low_detect(21, true);
+
     loop {
         let _ = gpio_high(29);
 
@@ -67,3 +100,29 @@ fn print_gpio_state() {
     print(s);
     print("\r\n");
 }
+
+pub fn get_current_el() -> u64 {
+    let el: u64;
+    unsafe {
+        asm!(
+            "mrs {el}, CurrentEL",
+            el = out(reg) el,
+            options(nomem, nostack, preserves_flags)
+        );
+    }
+    el >> 2
+}
+
+fn print_current_el_str() {
+    let el = get_current_el();
+    let el_str = match el {
+        0b11 => "Level 3",
+        0b10 => "Level 2",
+        0b01 => "Level 1",
+        0b00 => "Level 0",
+        _ => "Unknown EL",
+    };
+
+    print(el_str);
+    print("\r\n");
+}