-/*
- * Generic implementation of 64-bit atomics using spinlocks,
- * useful on processors that don't have 64-bit atomic instructions.
- *
- * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-#include <linux/types.h>
-#include <linux/cache.h>
-#include <linux/spinlock.h>
-#include <linux/atomic.h>
-
-#ifdef ATOMIC64_SPINLOCK
-
-/*
- * We use a hashed array of spinlocks to provide exclusive access
- * to each atomic64_t variable. Since this is expected to used on
- * systems with small numbers of CPUs (<= 4 or so), we use a
- * relatively small array of 16 spinlocks to avoid wasting too much
- * memory on the spinlock array.
- */
-#define NR_LOCKS 16
-
-/*
- * Ensure each lock is in a separate cacheline.
- */
-static union {
- raw_spinlock_t lock;
- char pad[L1_CACHE_BYTES];
-} atomic64_lock[NR_LOCKS] ____cacheline_aligned_in_smp = {
- [0 ... (NR_LOCKS - 1)] = {
- .lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock),
- },
-};
-
-static inline raw_spinlock_t *lock_addr(const atomic64_t *v)
-{
- unsigned long addr = (unsigned long) v;
-
- addr >>= L1_CACHE_SHIFT;
- addr ^= (addr >> 8) ^ (addr >> 16);
- return &atomic64_lock[addr & (NR_LOCKS - 1)].lock;
-}
-
-long long atomic64_read(const atomic64_t *v)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
- long long val;
-
- raw_spin_lock_irqsave(lock, flags);
- val = v->counter;
- raw_spin_unlock_irqrestore(lock, flags);
- return val;
-}
-
-void atomic64_set(atomic64_t *v, long long i)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
-
- raw_spin_lock_irqsave(lock, flags);
- v->counter = i;
- raw_spin_unlock_irqrestore(lock, flags);
-}
-
-#define ATOMIC64_OP(op, c_op) \
-void atomic64_##op(long long a, atomic64_t *v) \
-{ \
- unsigned long flags; \
- raw_spinlock_t *lock = lock_addr(v); \
- \
- raw_spin_lock_irqsave(lock, flags); \
- v->counter c_op a; \
- raw_spin_unlock_irqrestore(lock, flags); \
-}
-
-#define ATOMIC64_OP_RETURN(op, c_op) \
-long long atomic64_##op##_return(long long a, atomic64_t *v) \
-{ \
- unsigned long flags; \
- raw_spinlock_t *lock = lock_addr(v); \
- long long val; \
- \
- raw_spin_lock_irqsave(lock, flags); \
- val = (v->counter c_op a); \
- raw_spin_unlock_irqrestore(lock, flags); \
- return val; \
-}
-
-#define ATOMIC64_FETCH_OP(op, c_op) \
-long long atomic64_fetch_##op(long long a, atomic64_t *v) \
-{ \
- unsigned long flags; \
- raw_spinlock_t *lock = lock_addr(v); \
- long long val; \
- \
- raw_spin_lock_irqsave(lock, flags); \
- val = v->counter; \
- v->counter c_op a; \
- raw_spin_unlock_irqrestore(lock, flags); \
- return val; \
-}
-
-#define ATOMIC64_OPS(op, c_op) \
- ATOMIC64_OP(op, c_op) \
- ATOMIC64_OP_RETURN(op, c_op) \
- ATOMIC64_FETCH_OP(op, c_op)
-
-ATOMIC64_OPS(add, +=)
-ATOMIC64_OPS(sub, -=)
-
-#undef ATOMIC64_OPS
-#define ATOMIC64_OPS(op, c_op) \
- ATOMIC64_OP(op, c_op) \
- ATOMIC64_OP_RETURN(op, c_op) \
- ATOMIC64_FETCH_OP(op, c_op)
-
-ATOMIC64_OPS(and, &=)
-ATOMIC64_OPS(or, |=)
-ATOMIC64_OPS(xor, ^=)
-
-#undef ATOMIC64_OPS
-#undef ATOMIC64_FETCH_OP
-#undef ATOMIC64_OP_RETURN
-#undef ATOMIC64_OP
-
-long long atomic64_dec_if_positive(atomic64_t *v)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
- long long val;
-
- raw_spin_lock_irqsave(lock, flags);
- val = v->counter - 1;
- if (val >= 0)
- v->counter = val;
- raw_spin_unlock_irqrestore(lock, flags);
- return val;
-}
-
-long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
- long long val;
-
- raw_spin_lock_irqsave(lock, flags);
- val = v->counter;
- if (val == o)
- v->counter = n;
- raw_spin_unlock_irqrestore(lock, flags);
- return val;
-}
-
-long long atomic64_xchg(atomic64_t *v, long long new)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
- long long val;
-
- raw_spin_lock_irqsave(lock, flags);
- val = v->counter;
- v->counter = new;
- raw_spin_unlock_irqrestore(lock, flags);
- return val;
-}
-
-int atomic64_add_unless(atomic64_t *v, long long a, long long u)
-{
- unsigned long flags;
- raw_spinlock_t *lock = lock_addr(v);
- int ret = 0;
-
- raw_spin_lock_irqsave(lock, flags);
- if (v->counter != u) {
- v->counter += a;
- ret = 1;
- }
- raw_spin_unlock_irqrestore(lock, flags);
- return ret;
-}
-
-#endif