include/asm-s390/spinlock.h

   1 /*
   2  *  include/asm-s390/spinlock.h
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   7  *
   8  *  Derived from "include/asm-i386/spinlock.h"
   9  */
  10
  11 #ifndef __ASM_SPINLOCK_H
  12 #define __ASM_SPINLOCK_H
  13
  14 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
  15
  16 static inline int
  17 _raw_compare_and_swap(volatile unsigned int *lock,
  18                       unsigned int old, unsigned int new)
  19 {
  20         asm volatile(
  21                 "       cs      %0,%3,%1"
  22                 : "=d" (old), "=Q" (*lock)
  23                 : "0" (old), "d" (new), "Q" (*lock)
  24                 : "cc", "memory" );
  25         return old;
  26 }
  27
  28 #else /* __GNUC__ */
  29
  30 static inline int
  31 _raw_compare_and_swap(volatile unsigned int *lock,
  32                       unsigned int old, unsigned int new)
  33 {
  34         asm volatile(
  35                 "       cs      %0,%3,0(%4)"
  36                 : "=d" (old), "=m" (*lock)
  37                 : "0" (old), "d" (new), "a" (lock), "m" (*lock)
  38                 : "cc", "memory" );
  39         return old;
  40 }
  41
  42 #endif /* __GNUC__ */
  43
  44 /*
  45  * Simple spin lock operations.  There are two variants, one clears IRQ's
  46  * on the local processor, one does not.
  47  *
  48  * We make no fairness assumptions. They have a cost.
  49  *
  50  * (the type definitions are in asm/spinlock_types.h)
  51  */
  52
  53 #define __raw_spin_is_locked(x) ((x)->lock != 0)
  54 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
  55 #define __raw_spin_unlock_wait(lock) \
  56         do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
  57
  58 extern void _raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc);
  59 extern int _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc);
  60
  61 static inline void __raw_spin_lock(raw_spinlock_t *lp)
  62 {
  63         unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
  64
  65         if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0))
  66                 _raw_spin_lock_wait(lp, pc);
  67 }
  68
  69 static inline int __raw_spin_trylock(raw_spinlock_t *lp)
  70 {
  71         unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
  72
  73         if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0))
  74                 return 1;
  75         return _raw_spin_trylock_retry(lp, pc);
  76 }
  77
  78 static inline void __raw_spin_unlock(raw_spinlock_t *lp)
  79 {
  80         _raw_compare_and_swap(&lp->lock, lp->lock, 0);
  81 }
  82
  83 /*
  84  * Read-write spinlocks, allowing multiple readers
  85  * but only one writer.
  86  *
  87  * NOTE! it is quite common to have readers in interrupts
  88  * but no interrupt writers. For those circumstances we
  89  * can "mix" irq-safe locks - any writer needs to get a
  90  * irq-safe write-lock, but readers can get non-irqsafe
  91  * read-locks.
  92  */
  93
  94 /**
  95  * read_can_lock - would read_trylock() succeed?
  96  * @lock: the rwlock in question.
  97  */
  98 #define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
  99
 100 /**
 101  * write_can_lock - would write_trylock() succeed?
 102  * @lock: the rwlock in question.
 103  */
 104 #define __raw_write_can_lock(x) ((x)->lock == 0)
 105
 106 extern void _raw_read_lock_wait(raw_rwlock_t *lp);
 107 extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
 108 extern void _raw_write_lock_wait(raw_rwlock_t *lp);
 109 extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
 110
 111 static inline void __raw_read_lock(raw_rwlock_t *rw)
 112 {
 113         unsigned int old;
 114         old = rw->lock & 0x7fffffffU;
 115         if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
 116                 _raw_read_lock_wait(rw);
 117 }
 118
 119 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 120 {
 121         unsigned int old, cmp;
 122
 123         old = rw->lock;
 124         do {
 125                 cmp = old;
 126                 old = _raw_compare_and_swap(&rw->lock, old, old - 1);
 127         } while (cmp != old);
 128 }
 129
 130 static inline void __raw_write_lock(raw_rwlock_t *rw)
 131 {
 132         if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
 133                 _raw_write_lock_wait(rw);
 134 }
 135
 136 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 137 {
 138         _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
 139 }
 140
 141 static inline int __raw_read_trylock(raw_rwlock_t *rw)
 142 {
 143         unsigned int old;
 144         old = rw->lock & 0x7fffffffU;
 145         if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
 146                 return 1;
 147         return _raw_read_trylock_retry(rw);
 148 }
 149
 150 static inline int __raw_write_trylock(raw_rwlock_t *rw)
 151 {
 152         if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
 153                 return 1;
 154         return _raw_write_trylock_retry(rw);
 155 }
 156
 157 #endif /* __ASM_SPINLOCK_H */