[ARM] Add prefetch support for ARMv5.

include/asm-arm/processor.h

@@ -74,6 +74,29 @@ unsigned long get_wchan(struct task_struct *p);
  */
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
+/*
+ * Prefetching support - only ARMv5.
+ */
+#if __LINUX_ARM_ARCH__ >= 5
+
+#define ARCH_HAS_PREFETCH
+#define prefetch(ptr)				\
+	({					\
+		__asm__ __volatile__(		\
+		"pld\t%0"			\
+		:				\
+		: "o" (*(char *)(ptr))		\
+		: "cc");			\
+	})
+
+#define ARCH_HAS_PREFETCHW
+#define prefetchw(ptr)	prefetch(ptr)
+
+#define ARCH_HAS_SPINLOCK_PREFETCH
+#define spin_lock_prefetch(x) do { } while (0)
+
+#endif
+
 #endif
 
 #endif /* __ASM_ARM_PROCESSOR_H */