ARM64: Add support for some of atomic64 operations

These functions are needed in UBI/UBIFS on ZynqMP platform (ARM64).

Signed-off-by: Adam Oleksy <adam.oleksy@nokia.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>

arch/arm/include/asm/atomic.h

@@ -21,6 +21,11 @@
 #endif
 
 typedef struct { volatile int counter; } atomic_t;
+#if BITS_PER_LONG == 32
+typedef struct { volatile long long counter; } atomic64_t;
+#else /* BIT_PER_LONG == 32 */
+typedef struct { volatile long counter; } atomic64_t;
+#endif
 
 #define ATOMIC_INIT(i)	{ (i) }
 
@@ -28,7 +33,9 @@ typedef struct { volatile int counter; } atomic_t;
 #include <asm/proc-armv/system.h>
 
 #define atomic_read(v)	((v)->counter)
-#define atomic_set(v,i)	(((v)->counter) = (i))
+#define atomic_set(v, i)	(((v)->counter) = (i))
+#define atomic64_read(v)	atomic_read(v)
+#define atomic64_set(v, i)	atomic_set(v, i)
 
 static inline void atomic_add(int i, volatile atomic_t *v)
 {
@@ -101,6 +108,65 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 	local_irq_restore(flags);
 }
 
+#if BITS_PER_LONG == 32
+
+static inline void atomic64_add(long long i, volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter += i;
+	local_irq_restore(flags);
+}
+
+static inline void atomic64_sub(long long i, volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter -= i;
+	local_irq_restore(flags);
+}
+
+#else /* BIT_PER_LONG == 32 */
+
+static inline void atomic64_add(long i, volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter += i;
+	local_irq_restore(flags);
+}
+
+static inline void atomic64_sub(long i, volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter -= i;
+	local_irq_restore(flags);
+}
+#endif
+
+static inline void atomic64_inc(volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter += 1;
+	local_irq_restore(flags);
+}
+
+static inline void atomic64_dec(volatile atomic64_t *v)
+{
+	unsigned long flags = 0;
+
+	local_irq_save(flags);
+	v->counter -= 1;
+	local_irq_restore(flags);
+}
+
 /* Atomic operations are already serializing on ARM */
 #define smp_mb__before_atomic_dec()	barrier()
 #define smp_mb__after_atomic_dec()	barrier()