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-rw-r--r--include/asm-arm/atomic.h31
1 files changed, 31 insertions, 0 deletions
diff --git a/include/asm-arm/atomic.h b/include/asm-arm/atomic.h
index 2885972b085..8ab1689ef56 100644
--- a/include/asm-arm/atomic.h
+++ b/include/asm-arm/atomic.h
@@ -80,6 +80,23 @@ static inline int atomic_sub_return(int i, atomic_t *v)
return result;
}
+static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
+{
+ u32 oldval, res;
+
+ do {
+ __asm__ __volatile__("@ atomic_cmpxchg\n"
+ "ldrex %1, [%2]\n"
+ "teq %1, %3\n"
+ "strexeq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (&ptr->counter), "Ir" (old), "r" (new)
+ : "cc");
+ } while (res);
+
+ return oldval;
+}
+
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long tmp, tmp2;
@@ -131,6 +148,20 @@ static inline int atomic_sub_return(int i, atomic_t *v)
return val;
}
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+ int ret;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ ret = v->counter;
+ if (likely(ret == old))
+ v->counter = new;
+ local_irq_restore(flags);
+
+ return ret;
+}
+
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long flags;