Add setting of priority to interrupts

rtic-monotonics/Cargo.toml

@@ -48,14 +48,14 @@ systick-100hz = []
 systick-10khz = []
 
 # Timer peripheral on the RP2040
-rp2040 = ["dep:rp2040-pac"]
+rp2040 = ["dep:cortex-m", "dep:rp2040-pac"]
 
 # nRF Timers and RTC
-nrf52810 = ["dep:nrf52810-pac", "dep:critical-section"]
-nrf52811 = ["dep:nrf52811-pac", "dep:critical-section"]
-nrf52832 = ["dep:nrf52832-pac", "dep:critical-section"]
-nrf52833 = ["dep:nrf52833-pac", "dep:critical-section"]
-nrf52840 = ["dep:nrf52840-pac", "dep:critical-section"]
-nrf5340-app = ["dep:nrf5340-app-pac", "dep:critical-section"]
-nrf5340-net = ["dep:nrf5340-net-pac", "dep:critical-section"]
-nrf9160 = ["dep:nrf9160-pac", "dep:critical-section"]
+nrf52810 = ["dep:cortex-m", "dep:nrf52810-pac", "dep:critical-section"]
+nrf52811 = ["dep:cortex-m", "dep:nrf52811-pac", "dep:critical-section"]
+nrf52832 = ["dep:cortex-m", "dep:nrf52832-pac", "dep:critical-section"]
+nrf52833 = ["dep:cortex-m", "dep:nrf52833-pac", "dep:critical-section"]
+nrf52840 = ["dep:cortex-m", "dep:nrf52840-pac", "dep:critical-section"]
+nrf5340-app = ["dep:cortex-m", "dep:nrf5340-app-pac", "dep:critical-section"]
+nrf5340-net = ["dep:cortex-m", "dep:nrf5340-net-pac", "dep:critical-section"]
+nrf9160 = ["dep:cortex-m", "dep:nrf9160-pac", "dep:critical-section"]

rtic-monotonics/src/lib.rs

@@ -26,6 +26,42 @@ pub mod rp2040;
 ))]
 pub mod nrf;
 
+#[allow(dead_code)]
+pub(crate) const fn cortex_logical2hw(logical: u8, nvic_prio_bits: u8) -> u8 {
+    ((1 << nvic_prio_bits) - logical) << (8 - nvic_prio_bits)
+}
+
+#[cfg(any(
+    feature = "rp2040",
+    feature = "nrf52810",
+    feature = "nrf52811",
+    feature = "nrf52832",
+    feature = "nrf52833",
+    feature = "nrf52840",
+    feature = "nrf5340-app",
+    feature = "nrf5340-net",
+    feature = "nrf9160",
+))]
+pub(crate) unsafe fn set_monotonic_prio(
+    prio_bits: u8,
+    interrupt: impl cortex_m::interrupt::InterruptNumber,
+) {
+    extern "C" {
+        static RTIC_ASYNC_MAX_LOGICAL_PRIO: u8;
+    }
+
+    let max_prio = RTIC_ASYNC_MAX_LOGICAL_PRIO.max(1).min(1 << prio_bits);
+
+    let hw_prio = crate::cortex_logical2hw(max_prio, prio_bits);
+
+    // We take ownership of the entire IRQ and all settings to it, we only change settings
+    // for the IRQ we control.
+    // This will also compile-error in case the NVIC changes in size.
+    let mut nvic: cortex_m::peripheral::NVIC = core::mem::transmute(());
+
+    nvic.set_priority(interrupt, hw_prio);
+}
+
 /// This marker is implemented on an interrupt token to enforce that the right tokens
 /// are given to the correct monotonic implementation.
 ///

rtic-monotonics/src/nrf/rtc.rs

@@ -5,19 +5,22 @@
 //! ```
 //! use rtic_monotonics::nrf::rtc::*;
 //!
-//! # async fn usage() {
+//! fn init() {
+//!     # // This is normally provided by the selected PAC
 //!     # let rtc = unsafe { core::mem::transmute(()) };
 //!     // Generate the required token
 //!     let token = rtic_monotonics::create_nrf_rtc0_monotonic_token!();
 //!
 //!     // Start the monotonic
 //!     Rtc0::start(rtc, token);
+//! }
 //!
+//! async fn usage() {
 //!     loop {
 //!          // Use the monotonic
 //!          Rtc0::delay(100.millis()).await;
 //!     }
-//! # }
+//! }
 //! ```
 
 #[cfg(feature = "nrf52810")]
@@ -106,7 +109,13 @@ macro_rules! make_rtc {
 
                 $tq.initialize(Self {});
 
-                unsafe { pac::NVIC::unmask(Interrupt::$rtc) };
+                // SAFETY: We take full ownership of the peripheral and interrupt vector,
+                // plus we are not using any external shared resources so we won't impact
+                // basepri/source masking based critical sections.
+                unsafe {
+                    crate::set_monotonic_prio(pac::NVIC_PRIO_BITS, Interrupt::$rtc);
+                    pac::NVIC::unmask(Interrupt::$rtc);
+                }
             }
 
             /// Used to access the underlying timer queue

rtic-monotonics/src/nrf/timer.rs

@@ -5,19 +5,22 @@
 //! ```
 //! use rtic_monotonics::nrf::timer::*;
 //!
-//! # async fn usage() {
+//! fn init() {
+//!     # // This is normally provided by the selected PAC
 //!     # let timer = unsafe { core::mem::transmute(()) };
 //!     // Generate the required token
 //!     let token = rtic_monotonics::create_nrf_timer0_monotonic_token!();
 //!
 //!     // Start the monotonic
 //!     Timer0::start(timer, token);
+//! }
 //!
+//! async fn usage() {
 //!     loop {
 //!          // Use the monotonic
 //!          Timer0::delay(100.millis()).await;
 //!     }
-//! # }
+//! }
 //! ```
 
 use super::super::Monotonic;
@@ -135,7 +138,13 @@ macro_rules! make_timer {
                 timer.events_compare[0].write(|w| w);
                 timer.events_compare[1].write(|w| w);
 
-                unsafe { pac::NVIC::unmask(Interrupt::$timer) };
+                // SAFETY: We take full ownership of the peripheral and interrupt vector,
+                // plus we are not using any external shared resources so we won't impact
+                // basepri/source masking based critical sections.
+                unsafe {
+                    crate::set_monotonic_prio(pac::NVIC_PRIO_BITS, Interrupt::$timer);
+                    pac::NVIC::unmask(Interrupt::$timer);
+                }
             }
 
             /// Used to access the underlying timer queue

rtic-monotonics/src/rp2040.rs

@@ -5,7 +5,8 @@
 //! ```
 //! use rtic_monotonics::rp2040::*;
 //!
-//! # async fn usage() {
+//! fn init() {
+//!     # // This is normally provided by the selected PAC
 //!     # let timer = unsafe { core::mem::transmute(()) };
 //!     # let mut resets = unsafe { core::mem::transmute(()) };
 //!     // Generate the required token
@@ -13,12 +14,14 @@
 //!
 //!     // Start the monotonic
 //!     Timer::start(timer, &mut resets, token);
+//! }
 //!
+//! async fn usage() {
 //!     loop {
 //!          // Use the monotonic
 //!          Timer::delay(100.millis()).await;
 //!     }
-//! # }
+//! }
 //! ```
 
 use super::Monotonic;
@@ -43,7 +46,10 @@ impl Timer {
 
         TIMER_QUEUE.initialize(Self {});
 
-        unsafe { NVIC::unmask(Interrupt::TIMER_IRQ_0) };
+        unsafe {
+            crate::set_monotonic_prio(rp2040_pac::NVIC_PRIO_BITS, Interrupt::TIMER_IRQ_0);
+            NVIC::unmask(Interrupt::TIMER_IRQ_0);
+        }
     }
 
     fn timer() -> &'static timer::RegisterBlock {

rtic-monotonics/src/systick.rs

@@ -6,19 +6,22 @@
 //! ```
 //! use rtic_monotonics::systick::*;
 //!
-//! # async fn usage() {
+//! fn init() {
+//!     # // This is normally provided by the selected PAC
 //!     # let systick = unsafe { core::mem::transmute(()) };
 //!     // Generate the required token
 //!     let systick_token = rtic_monotonics::create_systick_token!();
 //!
 //!     // Start the monotonic
 //!     Systick::start(systick, 12_000_000, systick_token);
+//! }
 //!
+//! async fn usage() {
 //!     loop {
 //!          // Use the monotonic
 //!          Systick::delay(100.millis()).await;
 //!     }
-//! # }
+//! }
 //! ```
 
 use super::Monotonic;