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 #include <linux/smp.h>
  15
  16 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
  17
  18 static inline int
  19 _raw_compare_and_swap(volatile unsigned int *lock,
  20                       unsigned int old, unsigned int new)
  21 {
  22         asm volatile(
  23                 "       cs      %0,%3,%1"
  24                 : "=d" (old), "=Q" (*lock)
  25                 : "0" (old), "d" (new), "Q" (*lock)
  26                 : "cc", "memory" );
  27         return old;
  28 }
  29
  30 #else /* __GNUC__ */
  31
  32 static inline int
  33 _raw_compare_and_swap(volatile unsigned int *lock,
  34                       unsigned int old, unsigned int new)
  35 {
  36         asm volatile(
  37                 "       cs      %0,%3,0(%4)"
  38                 : "=d" (old), "=m" (*lock)
  39                 : "0" (old), "d" (new), "a" (lock), "m" (*lock)
  40                 : "cc", "memory" );
  41         return old;
  42 }
  43
  44 #endif /* __GNUC__ */
  45
  46 /*
  47  * Simple spin lock operations.  There are two variants, one clears IRQ's
  48  * on the local processor, one does not.
  49  *
  50  * We make no fairness assumptions. They have a cost.
  51  *
  52  * (the type definitions are in asm/spinlock_types.h)
  53  */
  54
  55 #define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
  56 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
  57 #define __raw_spin_unlock_wait(lock) \
  58         do { while (__raw_spin_is_locked(lock)) \
  59                  _raw_spin_relax(lock); } while (0)
  60
  61 extern void _raw_spin_lock_wait(raw_spinlock_t *);
  62 extern int _raw_spin_trylock_retry(raw_spinlock_t *);
  63 extern void _raw_spin_relax(raw_spinlock_t *lock);
  64
  65 static inline void __raw_spin_lock(raw_spinlock_t *lp)
  66 {
  67         int old;
  68
  69         old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
  70         if (likely(old == 0))
  71                 return;
  72         _raw_spin_lock_wait(lp);
  73 }
  74
  75 static inline int __raw_spin_trylock(raw_spinlock_t *lp)
  76 {
  77         int old;
  78
  79         old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
  80         if (likely(old == 0))
  81                 return 1;
  82         return _raw_spin_trylock_retry(lp);
  83 }
  84
  85 static inline void __raw_spin_unlock(raw_spinlock_t *lp)
  86 {
  87         _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
  88 }
  89
  90 /*
  91  * Read-write spinlocks, allowing multiple readers
  92  * but only one writer.
  93  *
  94  * NOTE! it is quite common to have readers in interrupts
  95  * but no interrupt writers. For those circumstances we
  96  * can "mix" irq-safe locks - any writer needs to get a
  97  * irq-safe write-lock, but readers can get non-irqsafe
  98  * read-locks.
  99  */
 100
 101 /**
 102  * read_can_lock - would read_trylock() succeed?
 103  * @lock: the rwlock in question.
 104  */
 105 #define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
 106
 107 /**
 108  * write_can_lock - would write_trylock() succeed?
 109  * @lock: the rwlock in question.
 110  */
 111 #define __raw_write_can_lock(x) ((x)->lock == 0)
 112
 113 extern void _raw_read_lock_wait(raw_rwlock_t *lp);
 114 extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
 115 extern void _raw_write_lock_wait(raw_rwlock_t *lp);
 116 extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
 117
 118 static inline void __raw_read_lock(raw_rwlock_t *rw)
 119 {
 120         unsigned int old;
 121         old = rw->lock & 0x7fffffffU;
 122         if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
 123                 _raw_read_lock_wait(rw);
 124 }
 125
 126 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 127 {
 128         unsigned int old, cmp;
 129
 130         old = rw->lock;
 131         do {
 132                 cmp = old;
 133                 old = _raw_compare_and_swap(&rw->lock, old, old - 1);
 134         } while (cmp != old);
 135 }
 136
 137 static inline void __raw_write_lock(raw_rwlock_t *rw)
 138 {
 139         if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
 140                 _raw_write_lock_wait(rw);
 141 }
 142
 143 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 144 {
 145         _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
 146 }
 147
 148 static inline int __raw_read_trylock(raw_rwlock_t *rw)
 149 {
 150         unsigned int old;
 151         old = rw->lock & 0x7fffffffU;
 152         if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
 153                 return 1;
 154         return _raw_read_trylock_retry(rw);
 155 }
 156
 157 static inline int __raw_write_trylock(raw_rwlock_t *rw)
 158 {
 159         if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
 160                 return 1;
 161         return _raw_write_trylock_retry(rw);
 162 }
 163
 164 #define _raw_read_relax(lock)   cpu_relax()
 165 #define _raw_write_relax(lock)  cpu_relax()
 166
 167 #endif /* __ASM_SPINLOCK_H */