1 files changed, 44 insertions, 0 deletions

diff --git a/include/asm-arm/atomic.h b/include/asm-arm/atomic.h
index 2885972b0855..d586f65c8228 100644
--- a/include/asm-arm/atomic.h
+++ b/include/asm-arm/atomic.h
@@ -12,6 +12,7 @@
 #define __ASM_ARM_ATOMIC_H
 
 #include <linux/config.h>
+#include <linux/compiler.h>
 
 typedef struct { volatile int counter; } atomic_t;
 
@@ -80,6 +81,24 @@ 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)
+{
+        unsigned long oldval, res;
+
+        do {
+                __asm__ __volatile__("@ atomic_cmpxchg\n"
+                "ldrex  %1, [%2]\n"
+                "mov    %0, #0\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 +150,20 @@ 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;
@@ -142,6 +175,17 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 
 #endif /* __LINUX_ARM_ARCH__ */
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+        int c, old;
+
+        c = atomic_read(v);
+        while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
+                c = old;
+        return c != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_add(i, v)        (void) atomic_add_return(i, v)
 #define atomic_inc(v)           (void) atomic_add_return(1, v)
 #define atomic_sub(i, v)        (void) atomic_sub_return(i, v)