error handling

src/lib.rs

@@ -35,3 +35,8 @@ pub fn mmio_read(address: u32) -> u32 {
 pub fn mmio_write(address: u32, data: u32) {
     unsafe { write_volatile(address as *mut u32, data) }
 }
+
+#[derive(Debug)]
+pub enum NovaError {
+    Mailbox,
+}

src/mailbox.rs

@@ -1,4 +1,4 @@
-use crate::{mmio_read, mmio_write, print};
+use crate::{mmio_read, mmio_write, NovaError};
 
 const MBOX_BASE: u32 = 0x3F00_0000 + 0xB880;
 
@@ -27,7 +27,9 @@ macro_rules! max {
 macro_rules! mailbox_command {
     ($name:ident, $tag:expr, $request_len:expr,$response_len:expr) => {
         /// More information at: https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
-        pub fn $name(request_data: [u32; $request_len / 4]) -> [u32; $response_len / 4] {
+        pub fn $name(
+            request_data: [u32; $request_len / 4],
+        ) -> Result<[u32; $response_len / 4], NovaError> {
             let mut mailbox =
                 [0u32; (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) / 4];
             mailbox[0] = (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) as u32; // Total length in Bytes
@@ -35,8 +37,8 @@ macro_rules! mailbox_command {
             mailbox[2] = $tag; // Command Tag
             mailbox[3] = max!($request_len, $response_len) as u32; // Max value buffer size
             mailbox[4] = $request_len;
-            mailbox[5..(5 + ($request_len / 4))].copy_from_slice(&request_data);
 
+            mailbox[5..(5 + ($request_len / 4))].copy_from_slice(&request_data);
             mailbox[(5 + ($request_len / 4))..].fill(0);
 
             let addr = core::ptr::addr_of!(mailbox[0]) as u32;
@@ -46,17 +48,17 @@ macro_rules! mailbox_command {
             let _ = read_mailbox(8);
 
             if mailbox[1] == 0 {
-                println!("Mailbox Command Failed!");
+                return Err(NovaError::Mailbox);
             }
 
             let mut out = [0u32; $response_len / 4]; // TODO: Can this be improved?
             out.copy_from_slice(&mailbox[5..(5 + $response_len / 4)]);
-            out
+            Ok(out)
         }
     };
 }
 
-mailbox_command!(read_soc_temp, 0x00030006, 4, 8);
+mailbox_command!(mb_read_soc_temp, 0x00030006, 4, 8);
 
 pub fn read_mailbox(channel: u32) -> u32 {
     // Wait until mailbox is not empty

src/main.rs

@@ -11,7 +11,7 @@ use core::{
 use nova::{
     framebuffer::{print_display_resolution, FrameBuffer, BLUE, GREEN, ORANGE, RED, YELLOW},
     irq_interrupt::enable_irq_source,
-    mailbox::read_soc_temp,
+    mailbox::mb_read_soc_temp,
     math::polar_to_cartesian,
     peripherals::{
         gpio::{
@@ -72,12 +72,13 @@ pub extern "C" fn main() -> ! {
         el2_to_el1();
     }
 
+    #[allow(clippy::empty_loop)]
     loop {}
 }
 
 unsafe fn zero_bss() {
-    let mut bss: *mut u32 = &raw mut __bss_start as *mut u32;
-    while bss < &raw mut __bss_end as *mut u32 {
+    let mut bss: *mut u32 = &raw mut __bss_start;
+    while bss < &raw mut __bss_end {
         write_volatile(bss, 0);
         bss = bss.add(1);
     }
@@ -123,7 +124,7 @@ pub extern "C" fn kernel_main() -> ! {
     fb.draw_function(cos, 100, 105, BLUE);
 
     loop {
-        let temp = read_soc_temp([0]);
+        let temp = mb_read_soc_temp([0]).unwrap();
         println!("{} °C", temp[1] / 1000);
 
         blink_gpio(SpecificGpio::OnboardLed as u8, 500);

src/peripherals/gpio.rs

@@ -77,7 +77,7 @@ pub fn gpio_get_state(gpio: u8) -> u8 {
     let register_addr = GPLEV_BASE + (register_index as u32 * 4);
 
     let state = mmio_read(register_addr);
-    return ((state >> register_offset) & 0b1) as u8;
+    ((state >> register_offset) & 0b1) as u8
 }
 
 /// Pull GPIO up

src/peripherals/uart.rs

@@ -20,7 +20,7 @@ const UART0_CR: u32 = 0x3F20_1030;
 const UART0_CR_UARTEN: u32 = 1 << 0;
 const UART0_CR_TXE: u32 = 1 << 8;
 
-const UART0_LCRH: u32 = 0x3F20_102c;
+const UART0_LCRH: u32 = 0x3F20_102C;
 const UART0_LCRH_FEN: u32 = 1 << 4;
 
 pub struct Uart;

src/timer.rs

@@ -3,7 +3,7 @@ use crate::mmio_read;
 const TIMER_CLO: u32 = 0x3F00_3004;
 
 fn read_clo() -> u32 {
-    return mmio_read(TIMER_CLO);
+    mmio_read(TIMER_CLO)
 }
 
 /// Sleep for `us` microseconds