--- /dev/null
+/*
+ * 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 _LWK_PREFETCH_H
+#define _LWK_PREFETCH_H
+
+#include <lwk/types.h>
+#include <arch/processor.h>
+#include <arch/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
