Add icache_enabled and dcache_enabled methods to SCB

1 files changed, 40 insertions, 13 deletions

diff --git a/src/peripheral/mod.rs b/src/peripheral/mod.rs
index 2dcfa30..b85f699 100644
--- a/src/peripheral/mod.rs
+++ b/src/peripheral/mod.rs
@@ -541,15 +541,17 @@ impl Scb {
 
 #[cfg(armv7m)]
 impl Scb {
-    /// Enables I-Cache
+    /// Enables I-Cache if currently disabled
     #[inline]
     pub fn enable_icache(&self) {
+        // Don't do anything if ICache is already enabled
+        if self.icache_enabled() {
+            return;
+        }
+
         // All of CBP is write-only so no data races are possible
         let cbp = unsafe { &mut *CBP.get() };
 
-        ::asm::dsb();
-        ::asm::isb();
-
         // Invalidate I-Cache
         cbp.iciallu();
 
@@ -560,15 +562,17 @@ impl Scb {
         ::asm::isb();
     }
 
-    /// Disables I-Cache
+    /// Disables I-Cache if currently enabled
     #[inline]
     pub fn disable_icache(&self) {
+        // Don't do anything if ICache is already disabled
+        if !self.icache_enabled() {
+            return;
+        }
+
         // All of CBP is write-only so no data races are possible
         let cbp = unsafe { &mut *CBP.get() };
 
-        ::asm::dsb();
-        ::asm::isb();
-
         // Disable I-Cache
         unsafe { self.ccr.modify(|r| r & !SCB_CCR_IC_MASK) };
 
@@ -579,15 +583,20 @@ impl Scb {
         ::asm::isb();
     }
 
+    /// Returns whether the I-Cache is currently enabled
+    #[inline]
+    pub fn icache_enabled(&self) -> bool {
+        ::asm::dsb();
+        ::asm::isb();
+        self.ccr.read() & SCB_CCR_IC_MASK == SCB_CCR_IC_MASK
+    }
+
     /// Invalidates I-Cache
     #[inline]
     pub fn invalidate_icache(&self) {
         // All of CBP is write-only so no data races are possible
         let cbp = unsafe { &mut *CBP.get() };
 
-        ::asm::dsb();
-        ::asm::isb();
-
         // Invalidate I-Cache
         cbp.iciallu();
 
@@ -595,9 +604,14 @@ impl Scb {
         ::asm::isb();
     }
 
-    /// Enables D-cache
+    /// Enables D-cache if currently disabled
     #[inline]
     pub fn enable_dcache(&self, cpuid: &Cpuid) {
+        // Don't do anything if DCache is already enabled
+        if self.dcache_enabled() {
+            return;
+        }
+
         // Invalidate anything currently in the DCache
         self.invalidate_dcache(cpuid);
 
@@ -608,9 +622,14 @@ impl Scb {
         ::asm::isb();
     }
 
-    /// Disables D-cache
+    /// Disables D-cache if currently enabled
     #[inline]
     pub fn disable_dcache(&self, cpuid: &Cpuid) {
+        // Don't do anything if DCache is already disabled
+        if !self.dcache_enabled() {
+            return;
+        }
+
         // Turn off the DCache
         unsafe { self.ccr.modify(|r| r & !SCB_CCR_DC_MASK) };
 
@@ -618,6 +637,14 @@ impl Scb {
         self.clean_invalidate_dcache(cpuid);
     }
 
+    /// Returns whether the D-Cache is currently enabled
+    #[inline]
+    pub fn dcache_enabled(&self) -> bool {
+        ::asm::dsb();
+        ::asm::isb();
+        self.ccr.read() & SCB_CCR_DC_MASK == SCB_CCR_DC_MASK
+    }
+
     /// Invalidates D-cache
     ///
     /// Note that calling this while the dcache is enabled will probably wipe out your