Kernel/arch/arm7/include/lock.h

   1 /*
   2  * Acess2
   3  * ARM7 Architecture
   4  *
   5  * lock.h - Hardware level spinlocks
   6  */
   7 #ifndef _LOCK_H_
   8 #define _LOCK_H_
   9
  10 // === CODE ===
  11 struct sShortSpinlock {
  12          int    Lock;
  13 };
  14
  15 // --- Spinlocks ---
  16 static inline int IS_LOCKED(struct sShortSpinlock *Lock)
  17 {
  18         return !!Lock->Lock;
  19 }
  20
  21 static inline int CPU_HAS_LOCK(struct sShortSpinlock *Lock)
  22 {
  23         // TODO: Handle multiple CPUs
  24         return !!Lock->Lock;
  25 }
  26
  27 static inline int SHORTLOCK(struct sShortSpinlock *Lock)
  28 {
  29         #if 0
  30         while( __sync_lock_test_and_set( &Lock->Lock, 1 ) == 1 );
  31         #elif 0
  32         while( Lock->Lock )     ;
  33         Lock->Lock = 1;
  34         #elif 1
  35          int    v = 1;
  36         while( v )
  37         {
  38                 __asm__ __volatile__ ("swp [%0], %1" : "=r" (v) : "r" (&lock));
  39         }
  40         #elif 0
  41         // Shamelessly copied from linux (/arch/arm/include/asm/spinlock.h) until I can fix stuff
  42         Uint    tmp;
  43         __asm__ __volatile__ (
  44         "1:     ldrex   %0, [%1]\n"
  45         "       teq     %0, #0\n"
  46         "       strexeq %0, %2, [%1]\n" // Magic? TODO: Look up
  47         "       teqeq   %0, #0\n"
  48         "       bne     1b"
  49                 : "=&r" (tmp)   // Temp
  50                 : "r" (&Lock->Lock), "r" (1)
  51                 : "cc"  // Condition codes clobbered
  52                 );
  53         #endif
  54         return 1;
  55 }
  56
  57 static inline void SHORTREL(struct sShortSpinlock *Lock)
  58 {
  59         Lock->Lock = 0;
  60 }
  61
  62 #endif
  63