Fixes for DWT on Cortex-M0

Author: korken89

src/peripheral/dwt.rs

@@ -10,25 +10,41 @@ pub struct RegisterBlock {
     /// Control
     pub ctrl: RW<u32>,
     /// Cycle Count
+    #[cfg(not(armv6m))]
     pub cyccnt: RW<u32>,
     /// CPI Count
+    #[cfg(not(armv6m))]
     pub cpicnt: RW<u32>,
     /// Exception Overhead Count
+    #[cfg(not(armv6m))]
     pub exccnt: RW<u32>,
     /// Sleep Count
+    #[cfg(not(armv6m))]
     pub sleepcnt: RW<u32>,
     /// LSU Count
+    #[cfg(not(armv6m))]
     pub lsucnt: RW<u32>,
     /// Folded-instruction Count
+    #[cfg(not(armv6m))]
     pub foldcnt: RW<u32>,
+    /// Cortex-M0(+) does not have  these parts
+    #[cfg(armv6m)]
+    reserved: [u32; 6],
     /// Program Counter Sample
     pub pcsr: RO<u32>,
     /// Comparators
+    #[cfg(armv6m)]
+    pub c: [Comparator; 2],
+    #[cfg(not(armv6m))]
+    /// Comparators
     pub c: [Comparator; 16],
+    #[cfg(not(armv6m))]
     reserved: [u32; 932],
     /// Lock Access
+    #[cfg(not(armv6m))]
     pub lar: WO<u32>,
     /// Lock Status
+    #[cfg(not(armv6m))]
     pub lsr: RO<u32>,
 }
 
@@ -46,11 +62,13 @@ pub struct Comparator {
 
 impl DWT {
     /// Enables the cycle counter
+    #[cfg(not(armv6m))]
     pub fn enable_cycle_counter(&mut self) {
         unsafe { self.ctrl.modify(|r| r | 1) }
     }
 
     /// Returns the current clock cycle count
+    #[cfg(not(armv6m))]
     pub fn get_cycle_count() -> u32 {
         // NOTE(unsafe) atomic read with no side effects
         unsafe { (*Self::ptr()).cyccnt.read() }