arch/arm-cortex-m0/include/lock.h

   1 #ifndef _ARCH_LOCK_H_
   2 #define _ARCH_LOCK_H_
   3
   4 #include <types.h>
   5
   6 struct lock {
   7         u32 primask;
   8 };
   9
  10 #define LOCK_INIT (struct lock) {}
  11
  12 static inline void lock_init(struct lock *lock)
  13 {
  14 }
  15
  16 // source:
  17 // http://embeddedfreak.wordpress.com/2009/08/14/cortex-m3-global-interruptexception-control/
  18 //
  19 // confirm this is correct by printing primask before after
  20
  21 // note arm architecture v7m rm... setting PRIMASK raises priority to 0
  22
  23 static inline void lock(struct lock *lock)
  24 {
  25         u32 tmp;
  26         asm volatile (
  27                 "mrs    %0, PRIMASK\n\t"
  28                 "cpsid  i\n\t"
  29                 : "=r" (tmp) );
  30         lock->primask = tmp;
  31 }
  32
  33 static inline void unlock(struct lock *lock)
  34 {
  35         asm volatile (
  36                 "msr    PRIMASK, %0\n\t"
  37                 : : "r" (lock->primask) );
  38 }
  39
  40 #endif