1 files changed, 69 insertions, 0 deletions

diff --git a/include/linux/prefetch.h b/include/linux/prefetch.h
new file mode 100644
index 000000000000..fc86f274147f
--- /dev/null
+++ b/include/linux/prefetch.h
@@ -0,0 +1,69 @@
+/*
+ *  Generic cache management functions. Everything is arch-specific,  
+ *  but this header exists to make sure the defines/functions can be
+ *  used in a generic way.
+ *
+ *  2000-11-13  Arjan van de Ven   <arjan@fenrus.demon.nl>
+ *
+ */
+
+#ifndef _LINUX_PREFETCH_H
+#define _LINUX_PREFETCH_H
+
+#include <linux/types.h>
+#include <asm/processor.h>
+#include <asm/cache.h>
+
+/*
+        prefetch(x) attempts to pre-emptively get the memory pointed to
+        by address "x" into the CPU L1 cache. 
+        prefetch(x) should not cause any kind of exception, prefetch(0) is
+        specifically ok.
+
+        prefetch() should be defined by the architecture, if not, the 
+        #define below provides a no-op define.  
+        
+        There are 3 prefetch() macros:
+        
+        prefetch(x)     - prefetches the cacheline at "x" for read
+        prefetchw(x)    - prefetches the cacheline at "x" for write
+        spin_lock_prefetch(x) - prefectches the spinlock *x for taking
+        
+        there is also PREFETCH_STRIDE which is the architecure-prefered 
+        "lookahead" size for prefetching streamed operations.
+        
+*/
+
+/*
+ *      These cannot be do{}while(0) macros. See the mental gymnastics in
+ *      the loop macro.
+ */
+ 
+#ifndef ARCH_HAS_PREFETCH
+static inline void prefetch(const void *x) {;}
+#endif
+
+#ifndef ARCH_HAS_PREFETCHW
+static inline void prefetchw(const void *x) {;}
+#endif
+
+#ifndef ARCH_HAS_SPINLOCK_PREFETCH
+#define spin_lock_prefetch(x) prefetchw(x)
+#endif
+
+#ifndef PREFETCH_STRIDE
+#define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
+#endif
+
+static inline void prefetch_range(void *addr, size_t len)
+{
+#ifdef ARCH_HAS_PREFETCH
+        char *cp;
+        char *end = addr + len;
+
+        for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
+                prefetch(cp);
+#endif
+}
+
+#endif