include/asm-ppc/semaphore-helper.h

   1 #ifdef __KERNEL__
   2 #ifndef _PPC_SEMAPHORE_HELPER_H
   3 #define _PPC_SEMAPHORE_HELPER_H
   4
   5 /*
   6  * SMP- and interrupt-safe semaphores..
   7  *
   8  * (C) Copyright 1996 Linus Torvalds
   9  * Adapted for PowerPC by Gary Thomas and Paul Mackerras
  10  */
  11
  12 #include <asm/atomic.h>
  13
  14 /*
  15  * These two (wake_one_more and waking_non_zero) _must_ execute
  16  * atomically wrt each other.
  17  *
  18  * This is trivially done with load with reservation and
  19  * store conditional on the ppc.
  20  */
  21
  22 static inline void wake_one_more(struct semaphore * sem)
  23 {
  24         atomic_inc(&sem->waking);
  25 }
  26
  27 static inline int waking_non_zero(struct semaphore *sem)
  28 {
  29         int ret, tmp;
  30
  31         /* Atomic decrement sem->waking iff it is > 0 */
  32         __asm__ __volatile__(
  33                 "1:     lwarx %1,0,%2\n"        /* tmp = sem->waking */
  34                 "       cmpwi 0,%1,0\n"         /* test tmp */
  35                 "       addic %1,%1,-1\n"       /* --tmp */
  36                 "       ble- 2f\n"              /* exit if tmp was <= 0 */
  37                 "       stwcx. %1,0,%2\n"       /* update sem->waking */
  38                 "       bne- 1b\n"              /* try again if update failed*/
  39                 "       li %0,1\n"              /* ret = 1 */
  40                 "2:"
  41                 : "=r" (ret), "=&r" (tmp)
  42                 : "r" (&sem->waking), "0" (0)
  43                 : "cr0", "memory");
  44
  45         return ret;
  46 }
  47 /*
  48  * waking_non_zero_interruptible:
  49  *      1       got the lock
  50  *      0       go to sleep
  51  *      -EINTR  interrupted
  52  */
  53 static inline int waking_non_zero_interruptible(struct semaphore *sem,
  54                                                 struct task_struct *tsk)
  55 {
  56         int ret, tmp;
  57
  58         /* Atomic decrement sem->waking iff it is > 0 */
  59         __asm__ __volatile__(
  60                 "1:     lwarx %1,0,%2\n"        /* tmp = sem->waking */
  61                 "       cmpwi 0,%1,0\n"         /* test tmp */
  62                 "       addic %1,%1,-1\n"       /* --tmp */
  63                 "       ble- 2f\n"              /* exit if tmp was <= 0 */
  64                 "       stwcx. %1,0,%2\n"       /* update sem->waking */
  65                 "       bne- 1b\n"              /* try again if update failed*/
  66                 "       li %0,1\n"              /* ret = 1 */
  67                 "2:"
  68                 : "=r" (ret), "=&r" (tmp)
  69                 : "r" (&sem->waking), "0" (0)
  70                 : "cr0", "memory");
  71
  72         if (ret == 0 && signal_pending(tsk)) {
  73                 atomic_inc(&sem->count);
  74                 ret = -EINTR;
  75         }
  76         return ret;
  77 }
  78
  79 /*
  80  * waking_non_zero_trylock:
  81  *      1       failed to lock
  82  *      0       got the lock
  83  */
  84 static inline int waking_non_zero_trylock(struct semaphore *sem)
  85 {
  86         int ret, tmp;
  87
  88         /* Atomic decrement sem->waking iff it is > 0 */
  89         __asm__ __volatile__(
  90                 "1:     lwarx %1,0,%2\n"        /* tmp = sem->waking */
  91                 "       cmpwi 0,%1,0\n"         /* test tmp */
  92                 "       addic %1,%1,-1\n"       /* --tmp */
  93                 "       ble- 2f\n"              /* exit if tmp was <= 0 */
  94                 "       stwcx. %1,0,%2\n"       /* update sem->waking */
  95                 "       bne- 1b\n"              /* try again if update failed*/
  96                 "       li %0,0\n"              /* ret = 0 */
  97                 "2:"
  98                 : "=r" (ret), "=&r" (tmp)
  99                 : "r" (&sem->waking), "0" (1)
 100                 : "cr0", "memory");
 101
 102         if (ret)
 103                 atomic_inc(&sem->count);
 104
 105         return ret;
 106 }
 107
 108 #endif /* _PPC_SEMAPHORE_HELPER_H */
 109 #endif /* __KERNEL__ */