style: fix clippy warnings

kernel/src/arch/aarch64/exception.rs

@@ -72,6 +72,7 @@ extern "C" fn __aa64_exc_sync_handler(exc: &mut ExceptionFrame) {
 
     debugln!("Unhandled exception at ELR={:#018x}", exc.elr);
 
+    #[allow(clippy::single_match)]
     match err_code {
         EC_DATA_ABORT_ELX => {
             debugln!("Data Abort:");

kernel/src/arch/aarch64/irq/gic/mod.rs

@@ -20,7 +20,7 @@ pub const MAX_IRQ: usize = 300;
 #[derive(Copy, Clone)]
 pub struct IrqNumber(usize);
 
-/// ARM Generic Interrupt Controller
+/// ARM Generic Interrupt Controller, version 2
 pub struct Gic {
     gicc: Gicc,
     gicd: Gicd,
@@ -34,7 +34,7 @@ impl IrqNumber {
         self.0
     }
 
-    ///
+    /// Checks and wraps an IRQ number
     #[inline(always)]
     pub const fn new(v: usize) -> Self {
         assert!(v < MAX_IRQ);
@@ -98,7 +98,11 @@ impl IntController for Gic {
 }
 
 impl Gic {
+    /// Constructs an instance of GICv2.
     ///
+    /// # Safety
+    ///
+    /// Does not perform `gicd_base` and `gicc_base` validation.
     pub const unsafe fn new(gicd_base: usize, gicc_base: usize) -> Self {
         Self {
             gicc: Gicc::new(gicc_base),

kernel/src/arch/aarch64/mach_orangepi3/gpio.rs

@@ -86,7 +86,7 @@ impl GpioDevice for Gpio {
         Ok(())
     }
 
-    unsafe fn get_pin_config(&self, _pin: u32) -> Result<PinConfig, Errno> {
+    fn get_pin_config(&self, _pin: u32) -> Result<PinConfig, Errno> {
         todo!()
     }
 

kernel/src/arch/aarch64/mach_orangepi3/mod.rs

@@ -51,7 +51,7 @@ pub fn local_timer() -> &'static impl TimestampSource {
     &LOCAL_TIMER
 }
 
-///
+/// Returns CPU's interrupt controller device
 #[inline]
 pub fn intc() -> &'static impl IntController<IrqNumber = IrqNumber> {
     &GIC

kernel/src/arch/aarch64/mach_qemu/mod.rs

@@ -41,7 +41,7 @@ pub fn local_timer() -> &'static impl TimestampSource {
     &LOCAL_TIMER
 }
 
-///
+/// Returns CPU's interrupt controller device
 #[inline]
 pub fn intc() -> &'static impl IntController<IrqNumber = IrqNumber> {
     &GIC

kernel/src/arch/aarch64/mod.rs

@@ -22,6 +22,10 @@ cfg_if! {
 }
 
 /// Masks IRQs and returns previous IRQ mask state
+///
+/// # Safety
+///
+/// Unsafe: disables IRQ handling temporarily
 #[inline(always)]
 pub unsafe fn irq_mask_save() -> u64 {
     let state = DAIF.get();
@@ -30,6 +34,11 @@ pub unsafe fn irq_mask_save() -> u64 {
 }
 
 /// Restores IRQ mask state
+///
+/// # Safety
+///
+/// Unsafe: modifies interrupt behavior. Must only be used in
+/// conjunction with [irq_mask_save]
 #[inline(always)]
 pub unsafe fn irq_restore(state: u64) {
     DAIF.set(state);

kernel/src/dev/gpio.rs

@@ -41,9 +41,13 @@ pub struct PinConfig {
 /// Generic GPIO controller interface
 pub trait GpioDevice: Device {
     /// Initializes configuration for given pin
+    ///
+    /// # Safety
+    ///
+    /// Unsafe: changes physical pin configuration
     unsafe fn set_pin_config(&self, pin: u32, cfg: &PinConfig) -> Result<(), Errno>;
     /// Returns current configuration of given pin
-    unsafe fn get_pin_config(&self, pin: u32) -> Result<PinConfig, Errno>;
+    fn get_pin_config(&self, pin: u32) -> Result<PinConfig, Errno>;
 
     /// Sets `pin` to HIGH state
     fn set_pin(&self, pin: u32);

kernel/src/dev/irq.rs

@@ -35,7 +35,11 @@ pub trait IntSource: Device {
 }
 
 impl<'q> IrqContext<'q> {
+    /// Constructs an IRQ context token
     ///
+    /// # Safety
+    ///
+    /// Only allowed to be constructed in top-level IRQ handlers
     #[inline(always)]
     pub unsafe fn new() -> Self {
         Self { _0: PhantomData }