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   1 /*
   2  * atomic32.c: 32-bit atomic_t implementation
   3  *
   4  * Copyright (C) 2004 Keith M Wesolowski
   5  * Copyright (C) 2007 Kyle McMartin
   6  *
   7  * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
   8  */
   9
  10 #include <asm/atomic.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/module.h>
  13
  14 #ifdef CONFIG_SMP
  15 #define ATOMIC_HASH_SIZE        4
  16 #define ATOMIC_HASH(a)  (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])
  17
  18 spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
  19         [0 ... (ATOMIC_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED
  20 };
  21
  22 #else /* SMP */
  23
  24 static DEFINE_SPINLOCK(dummy);
  25 #define ATOMIC_HASH_SIZE        1
  26 #define ATOMIC_HASH(a)          (&dummy)
  27
  28 #endif /* SMP */
  29
  30 int __atomic_add_return(int i, atomic_t *v)
  31 {
  32         int ret;
  33         unsigned long flags;
  34         spin_lock_irqsave(ATOMIC_HASH(v), flags);
  35
  36         ret = (v->counter += i);
  37
  38         spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
  39         return ret;
  40 }
  41 EXPORT_SYMBOL(__atomic_add_return);
  42
  43 int atomic_cmpxchg(atomic_t *v, int old, int new)
  44 {
  45         int ret;
  46         unsigned long flags;
  47
  48         spin_lock_irqsave(ATOMIC_HASH(v), flags);
  49         ret = v->counter;
  50         if (likely(ret == old))
  51                 v->counter = new;
  52
  53         spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
  54         return ret;
  55 }
  56 EXPORT_SYMBOL(atomic_cmpxchg);
  57
  58 int atomic_add_unless(atomic_t *v, int a, int u)
  59 {
  60         int ret;
  61         unsigned long flags;
  62
  63         spin_lock_irqsave(ATOMIC_HASH(v), flags);
  64         ret = v->counter;
  65         if (ret != u)
  66                 v->counter += a;
  67         spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
  68         return ret != u;
  69 }
  70 EXPORT_SYMBOL(atomic_add_unless);
  71
  72 /* Atomic operations are already serializing */
  73 void atomic_set(atomic_t *v, int i)
  74 {
  75         unsigned long flags;
  76
  77         spin_lock_irqsave(ATOMIC_HASH(v), flags);
  78         v->counter = i;
  79         spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
  80 }
  81 EXPORT_SYMBOL(atomic_set);
  82
  83 unsigned long ___set_bit(unsigned long *addr, unsigned long mask)
  84 {
  85         unsigned long old, flags;
  86
  87         spin_lock_irqsave(ATOMIC_HASH(addr), flags);
  88         old = *addr;
  89         *addr = old | mask;
  90         spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
  91
  92         return old & mask;
  93 }
  94 EXPORT_SYMBOL(___set_bit);
  95
  96 unsigned long ___clear_bit(unsigned long *addr, unsigned long mask)
  97 {
  98         unsigned long old, flags;
  99
 100         spin_lock_irqsave(ATOMIC_HASH(addr), flags);
 101         old = *addr;
 102         *addr = old & ~mask;
 103         spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
 104
 105         return old & mask;
 106 }
 107 EXPORT_SYMBOL(___clear_bit);
 108
 109 unsigned long ___change_bit(unsigned long *addr, unsigned long mask)
 110 {
 111         unsigned long old, flags;
 112
 113         spin_lock_irqsave(ATOMIC_HASH(addr), flags);
 114         old = *addr;
 115         *addr = old ^ mask;
 116         spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
 117
 118         return old & mask;
 119 }
 120 EXPORT_SYMBOL(___change_bit);
 121
 122 unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
 123 {
 124         unsigned long flags;
 125         u32 prev;
 126
 127         spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
 128         if ((prev = *ptr) == old)
 129                 *ptr = new;
 130         spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
 131
 132         return (unsigned long)prev;
 133 }
 134 EXPORT_SYMBOL(__cmpxchg_u32);