icache: Add ICACHE management (#22)

Add management functions for the ICACHE instruction cache peripheral.

Author: astapleton

src/icache.rs

@@ -0,0 +1,238 @@
+//! Instruction Cache management
+//!
+//! To enable the ICACHE in the default N-way set associative mode:
+//!
+//! ```
+//! let dp = ...;            // Device peripherals
+//! let mut icache = dp.ICACHE.enable();
+//! ```
+//!
+//! To enable the ICACHE in a specific mode (e.g. Direct-mapped):
+//!
+//! ```
+//! let dp = ...;            // Device peripherals
+//! let mut icache = dp.ICACHE.enable_direct_mapped();
+//! ```
+//!
+//! To invalidate the cache, use the ICache::invalidate() method:
+//!
+//! ```
+//! icache.invalidate();
+//! ```
+//!
+//! Performance monitoring of the cache is possible using the cache hit and
+//! miss counters:
+//!
+//! ```
+//! icache.enable_hit_counter();
+//! icache.enable_miss_counter();
+//!
+//! // do something
+//!
+//! let hit_count = icache.hit_count();
+//! let miss_count = icache.miss_count();
+//! ```
+//!
+//! Using interrupts to trigger cache invalidation and determine when it is
+//! complete:
+//!
+//! ```
+//! icache.start_invalidation();
+//!
+//! // In interrupt context
+//! if icache.check_event(Event::CacheInvalidationFinished) {
+//!     icache.clear_irq(Event::CacheInvalidationFinished)
+//! }
+//! ```
+//!
+
+use crate::stm32::ICACHE;
+
+pub enum Event {
+    CacheError,
+    CacheInvalidationFinished,
+}
+
+pub trait ICacheExt: Sized {
+    /// Enable in N-way set associative mode (default)
+    fn enable_n_way(self) -> ICache;
+
+    /// Enable in direct mapped mode
+    fn enable_direct_mapped(self) -> ICache;
+
+    /// Enable in default mode (N-way set associative)
+    fn enable(self) -> ICache {
+        self.enable_n_way()
+    }
+}
+
+impl ICacheExt for ICACHE {
+    fn enable_n_way(self) -> ICache {
+        ICache::new(self).enable_n_way()
+    }
+
+    fn enable_direct_mapped(self) -> ICache {
+        ICache::new(self).enable_direct_mapped()
+    }
+}
+
+pub struct ICache {
+    icache: ICACHE,
+}
+
+impl ICache {
+    fn new(icache: ICACHE) -> Self {
+        Self { icache }
+    }
+
+    fn wait_for_busy_complete(&self) {
+        while self.icache.sr().read().busyf().bit_is_set() {}
+    }
+
+    /// Enable the ICACHE in N-way associative mode
+    fn enable_n_way(self) -> Self {
+        // Wait for any ongoing cache invalidation operation to complete
+        self.wait_for_busy_complete();
+
+        self.icache
+            .cr()
+            .write(|w| w.waysel().set_bit().en().set_bit());
+
+        self
+    }
+
+    /// Enable the ICACHE in 1-way associative mode (direct mapping)
+    fn enable_direct_mapped(self) -> Self {
+        // Wait for any ongoing cache invalidation operation to complete
+        self.wait_for_busy_complete();
+
+        self.icache
+            .cr()
+            .write(|w| w.waysel().clear_bit().en().set_bit());
+
+        self
+    }
+
+    /// Disable the ICACHE
+    pub fn disable(mut self) -> ICACHE {
+        // Restore cache mode to default (N-way associative)
+        self.icache
+            .cr()
+            .write(|w| w.waysel().set_bit().en().clear_bit());
+
+        // Disable interrupts
+        self.icache
+            .ier()
+            .modify(|_, w| w.errie().clear_bit().bsyendie().clear_bit());
+
+        self.invalidate();
+
+        cortex_m::asm::dsb();
+        cortex_m::asm::isb();
+
+        self.free()
+    }
+
+    /// Invalidate the ICACHE. This will block while the cache is being
+    /// invalidated
+    pub fn invalidate(&mut self) {
+        self.start_cache_invalidation();
+
+        self.wait_for_busy_complete();
+
+        cortex_m::asm::dsb();
+        cortex_m::asm::isb();
+    }
+
+    /// Start cache invalidation
+    pub fn start_cache_invalidation(&mut self) {
+        self.icache.cr().modify(|_, w| w.cacheinv().set_bit());
+    }
+
+    /// Enable interrupts for the given event
+    pub fn listen(&mut self, event: Event) {
+        self.icache.ier().modify(|_, w| match event {
+            Event::CacheError => w.errie().set_bit(),
+            Event::CacheInvalidationFinished => w.bsyendie().set_bit(),
+        });
+    }
+
+    /// Disable interrupts for the given event
+    pub fn unlisten(&mut self, event: Event) {
+        self.icache.ier().modify(|_, w| match event {
+            Event::CacheError => w.errie().clear_bit(),
+            Event::CacheInvalidationFinished => w.bsyendie().clear_bit(),
+        });
+    }
+
+    /// Clear the IRQ for the given event
+    pub fn clear_irq(&mut self, event: Event) {
+        self.icache.fcr().write(|w| match event {
+            Event::CacheError => w.cerrf().set_bit(),
+            Event::CacheInvalidationFinished => w.cbsyendf().set_bit(),
+        });
+    }
+
+    /// Check whether an interrupt event has occurred. Returns true if it has.
+    /// Clear the event IRQ by calling `clear_event`
+    pub fn check_event(&mut self, event: Event) -> bool {
+        let sr = self.icache.sr().read();
+        match event {
+            Event::CacheError => sr.errf().bit_is_set(),
+            Event::CacheInvalidationFinished => sr.bsyendf().bit_is_set(),
+        }
+    }
+
+    /// Enable the cache hit counter. The number of hits can be queried with ICache::hit_counter()
+    pub fn start_hit_counter(&mut self) {
+        // Enable and reset the cache hit counter
+        self.icache
+            .cr()
+            .modify(|_, w| w.hitmrst().set_bit().hitmen().set_bit());
+    }
+
+    /// Get the current value of the hit counter
+    pub fn hit_count(&self) -> u32 {
+        self.icache.hmonr().read().hitmon().bits()
+    }
+
+    /// Reset the hit counter
+    pub fn reset_hit_counter(&mut self) {
+        self.icache.cr().modify(|_, w| w.hitmrst().set_bit());
+    }
+
+    /// Disable the hit counter. The hit counter is disabled when the peripheral
+    /// is disabled
+    pub fn stop_hit_counter(&mut self) {
+        self.icache.cr().modify(|_, w| w.hitmen().clear_bit());
+    }
+
+    /// Enable the cache miss counter
+    pub fn start_miss_counter(&mut self) {
+        // Enable and reset the miss counter
+        self.icache
+            .cr()
+            .modify(|_, w| w.missmrst().set_bit().missmen().set_bit());
+    }
+
+    /// Get the current value of the miss counter
+    pub fn miss_count(&self) -> u16 {
+        self.icache.mmonr().read().missmon().bits()
+    }
+
+    /// Reset the miss counter
+    pub fn reset_miss_counter(&mut self) {
+        self.icache.cr().modify(|_, w| w.missmrst().set_bit());
+    }
+
+    /// Disable the miss counter. The miss counter is disabled when the ICACHE
+    /// is disabled
+    pub fn stop_miss_counter(&mut self) {
+        self.icache.cr().modify(|_, w| w.missmen().clear_bit());
+    }
+
+    // Deconstruct and return ICACHE
+    pub fn free(self) -> ICACHE {
+        self.icache
+    }
+}

src/lib.rs

@@ -52,6 +52,9 @@ pub mod rcc;
 #[cfg(feature = "device-selected")]
 pub mod gpio;
 
+#[cfg(feature = "device-selected")]
+pub mod icache;
+
 /// Get the name of the type without the module prefix(es)
 fn stripped_type_name<T>() -> &'static str {
     let s = core::any::type_name::<T>();

src/prelude.rs

@@ -1,6 +1,7 @@
 //! Prelude
 
 pub use crate::gpio::GpioExt as _stm32h5xx_hal_gpio_GpioExt;
+pub use crate::icache::ICacheExt as _stm32h5xx_hal_delay_ICacheExt;
 pub use crate::pwr::PwrExt as _stm32h5xx_hal_pwr_PwrExt;
 pub use crate::rcc::RccExt as _stm32h5xx_hal_rcc_RccExt;