diff options
Diffstat (limited to 'include/asm-arm')
| -rw-r--r-- | include/asm-arm/atomic.h | 31 |
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; |