Readme and cleanup

README.md

@@ -0,0 +1,5 @@
+# NovaOS
+
+NovaOS is a expository project where I build a kernel from scratch for a Raspberry PI 3 B+.
+
+[Technical write-up](https://blog.leafnova.net/projects/pi3_kernel/)

src/gpio.rs

@@ -1,9 +1,9 @@
 use core::ptr::{read_volatile, write_volatile};
+use core::result::Result;
+use core::result::Result::Err;
+use core::result::Result::Ok;
 
-use crate::{
+use crate::timer::delay_nops;
-    timer::delay_nops,
-    uart::{self},
-};
 
 const GPFSEL_BASE: u32 = 0x3F20_0000;
 const GPSET_BASE: u32 = 0x3F20_001C;

src/interrupt.rs

@@ -1,7 +1,4 @@
-use core::{
+use core::ptr::{read_volatile, write_volatile};
-    arch::asm,
-    ptr::{read_volatile, write_volatile},
-};
 
 use crate::uart::print;
 

src/lib.rs

@@ -0,0 +1,6 @@
+#![no_std]
+
+pub mod gpio;
+pub mod interrupt;
+pub mod timer;
+pub mod uart;

src/main.rs

@@ -7,17 +7,15 @@ use core::{
     panic::PanicInfo,
 };
 
-use gpio::{
+use nova::{
-    gpio_enable_low_detect, gpio_get_state, gpio_high, gpio_low, gpio_pull_up, set_gpio_state,
+    gpio::{
+        gpio_enable_low_detect, gpio_get_state, gpio_high, gpio_low, gpio_pull_up, set_gpio_state,
+        GPIOState,
+    },
+    interrupt::enable_iqr_source,
+    timer::{delay_nops, sleep},
+    uart::{print, uart_init},
 };
-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"));
 
@@ -28,7 +26,7 @@ extern "C" {
 #[panic_handler]
 fn panic(_panic: &PanicInfo) -> ! {
     loop {
-        uart::print("Panic\r\n");
+        print("Panic\r\n");
     }
 }
 
@@ -46,19 +44,19 @@ pub unsafe extern "C" fn _start() {
 
 #[no_mangle]
 pub extern "C" fn main() -> ! {
-    uart::uart_init();
+    uart_init();
     // Set ACT Led to Outout
-    let _ = set_gpio_state(21, gpio::GPIOState::Output);
+    let _ = set_gpio_state(21, GPIOState::Output);
 
     // Set GPIO Pins to UART
-    let _ = set_gpio_state(14, gpio::GPIOState::Alternative0);
+    let _ = set_gpio_state(14, GPIOState::Alternative0);
-    let _ = set_gpio_state(15, gpio::GPIOState::Alternative0);
+    let _ = set_gpio_state(15, GPIOState::Alternative0);
 
     print_current_el_str();
 
     // Delay so clock speed can stabilize
     delay_nops(50000);
-    uart::print("Hello World!\r\n");
+    print("Hello World!\r\n");
 
     unsafe {
         el2_to_el1();
@@ -69,14 +67,13 @@ pub extern "C" fn main() -> ! {
 
 #[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);
+    let _ = set_gpio_state(21, GPIOState::Input);
     gpio_pull_up(21);
     gpio_enable_low_detect(21, true);
 

src/vector.S

@@ -16,6 +16,8 @@ vector_table:
 
     ventry .
     ventry irq_handler     // IRQ(Interrupt Request) 0x280
+    ventry .
+    ventry .
 
 
 .align 4
@@ -25,26 +27,23 @@ el2_to_el1:
 
     mov x0, #(1 << 31)
     msr HCR_EL2, x0
-    isb
 
-    // Set SPSR_EL2: return to EL1h (EL1, using SP_EL1)
+    // Set SPSR_EL2: return to EL1h
     mov x0, #(0b0101)
     msr SPSR_EL2, x0
-    isb
 
     // Set return address to ELR_EL2
     ldr x0, =kernel_main
     msr ELR_EL2, x0
-    isb
 
     // Set SP_EL1 to stack base
     ldr x0, =__stack_end
     msr SP_EL1, x0
-    isb
 
     // Set VBAR_EL1 to vector table
     adr x0, vector_table
     msr VBAR_EL1, x0
+
     isb
 
     // Return to EL1