Add flipperzero::furi::kernel module

This module exposes most of the `furi_kernel_*` APIs.

Centralizing these lets us remove a number of `unsafe` calls peppered
across the codebase and allows things like providing optimized versions.

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ### Added
 
 - `flipperzero::dialogs::DialogFileBrowserOptions`
+- `flipperzero::furi::kernel` module exposing most `furi_kernel_*` APIs
 
 ### Changed
 

crates/flipperzero/src/furi/kernel.rs

@@ -0,0 +1,90 @@
+//! Furi Kernel primitives.
+
+use flipperzero_sys as sys;
+use ufmt::derive::uDebug;
+
+use crate::furi;
+
+/// Check if CPU is in IRQ; or kernel running and IRQ is masked.
+pub fn is_irq_or_masked() -> bool {
+    unsafe { sys::furi_kernel_is_irq_or_masked() }
+}
+
+/// Check if kernel is running.
+pub fn is_running() -> bool {
+    unsafe { sys::furi_kernel_is_running() }
+}
+
+/// Kernel lock state.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, uDebug)]
+pub enum LockState {
+    /// normal scheduling
+    Unlocked = 0,
+    /// scheduling paused
+    Locked = 1,
+}
+
+impl From<i32> for LockState {
+    fn from(value: i32) -> Self {
+        match value {
+            0 => LockState::Unlocked,
+            // Assume any non-zero value is `Locked``.
+            // This can be modified if new lock states are added in the future.
+            _ => LockState::Locked,
+        }
+    }
+}
+
+impl From<LockState> for i32 {
+    fn from(value: LockState) -> Self {
+        value as i32
+    }
+}
+
+/// Lock kernel, pause process scheduling.
+///
+/// <div class="warning">This should never be called in an interrupt request context.</div>
+///
+/// Returns previous lock state.
+pub fn lock() -> furi::Result<LockState> {
+    let status = sys::furi::Status::from(unsafe { sys::furi_kernel_lock() });
+
+    status.err_or_else(|status| status.0.into())
+}
+
+/// Unlock kernel, resume process scheduling.
+///
+/// <div class="warning">This should never be called in an interrupt request context.</div>
+///
+/// Returns previous lock state.
+pub fn unlock() -> furi::Result<LockState> {
+    let status = sys::furi::Status::from(unsafe { sys::furi_kernel_unlock() });
+
+    status.err_or_else(|status| status.0.into())
+}
+
+/// Restore kernel lock state.
+///
+/// <div class="warning">This should never be called in an interrupt request context.</div>
+///
+/// Returns previous lock state.
+pub fn restore_lock(state: LockState) -> furi::Result<LockState> {
+    let status = sys::furi::Status::from(unsafe { sys::furi_kernel_restore_lock(state.into()) });
+
+    status.err_or_else(|status| status.0.into())
+}
+
+/// Return kernel tick frequency in hertz.
+#[inline]
+pub fn get_tick_frequency() -> u32 {
+    unsafe { sys::furi_kernel_get_tick_frequency() }
+}
+
+/// Return current kernel tick value.
+///
+/// The duration of a tick depends on kernel configuration.
+/// The value can be discovered with [`get_tick_frequency`].
+#[inline]
+pub fn get_tick() -> u32 {
+    unsafe { sys::furi_get_tick() }
+}

crates/flipperzero/src/furi/mod.rs

@@ -1,6 +1,7 @@
 //! Furi API.
 
 pub mod io;
+pub mod kernel;
 pub mod log;
 pub mod message_queue;
 pub mod rng;

crates/flipperzero/src/furi/time.rs

@@ -2,9 +2,10 @@ use core::cmp::Ordering;
 use core::iter::Sum;
 use core::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
 
-use flipperzero_sys as sys;
 use ufmt::derive::uDebug;
 
+use crate::furi;
+
 /// Maximum number of ticks a [`Duration`] can contain to be usable with [`Instant`].
 const MAX_INTERVAL_DURATION_TICKS: u32 = u32::MAX / 2;
 
@@ -16,7 +17,7 @@ const MILLIS_PER_SEC: u32 = 1_000;
 
 /// Converts the given number of nanoseconds to ticks.
 fn ns_to_ticks(nanos: u64) -> u64 {
-    let rate = unsafe { sys::furi_kernel_get_tick_frequency() };
+    let rate = furi::kernel::get_tick_frequency();
     if rate == MILLIS_PER_SEC {
         // This can be up to around 2^45 ticks.
         nanos / NANOS_PER_MILLI
@@ -31,7 +32,7 @@ fn ns_to_ticks(nanos: u64) -> u64 {
 ///
 /// The upper 2 bits of the return value will always be zero.
 fn ticks_to_ns(ticks: u32) -> u64 {
-    let rate = unsafe { sys::furi_kernel_get_tick_frequency() };
+    let rate = furi::kernel::get_tick_frequency();
     if rate == MILLIS_PER_SEC {
         // This can be up to around 2^52 nanoseconds.
         (ticks as u64) * NANOS_PER_MILLI
@@ -49,7 +50,7 @@ impl Instant {
     /// Returns an instant corresponding to "now".
     #[must_use]
     pub fn now() -> Instant {
-        Instant(unsafe { sys::furi_get_tick() })
+        Instant(furi::kernel::get_tick())
     }
 
     /// Returns the amount of time elapsed from another instant to this one.