sparc32: Add cmpxchg64().

This fixes the build with i40e driver enabled.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/cmpxchg_32.h b/arch/sparc/include/asm/cmpxchg_32.h
index 83ffb83..a0101a5 100644
--- a/arch/sparc/include/asm/cmpxchg_32.h
+++ b/arch/sparc/include/asm/cmpxchg_32.h
@@ -62,6 +62,9 @@
 			(unsigned long)_n_, sizeof(*(ptr)));		\
 })
 
+u64 __cmpxchg_u64(u64 *ptr, u64 old, u64 new);
+#define cmpxchg64(ptr, old, new)	__cmpxchg_u64(ptr, old, new)
+
 #include <asm-generic/cmpxchg-local.h>
 
 /*
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index 2c37332..ddacb5a 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -172,6 +172,20 @@
 }
 EXPORT_SYMBOL(__cmpxchg_u32);
 
+u64 __cmpxchg_u64(u64 *ptr, u64 old, u64 new)
+{
+	unsigned long flags;
+	u64 prev;
+
+	spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
+	if ((prev = *ptr) == old)
+		*ptr = new;
+	spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
+
+	return prev;
+}
+EXPORT_SYMBOL(__cmpxchg_u64);
+
 unsigned long __xchg_u32(volatile u32 *ptr, u32 new)
 {
 	unsigned long flags;