1 files changed, 61 insertions, 0 deletions
diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h
new file mode 100644
index 000000000..65e4468ac
--- /dev/null
+++ b/include/asm-generic/getorder.h
@@ -0,0 +1,61 @@
+#ifndef __ASM_GENERIC_GETORDER_H
+#define __ASM_GENERIC_GETORDER_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/compiler.h>
+#include <linux/log2.h>
+
+/*
+ * Runtime evaluation of get_order()
+ */
+static inline __attribute_const__
+int __get_order(unsigned long size)
+{
+	int order;
+
+	size--;
+	size >>= PAGE_SHIFT;
+#if BITS_PER_LONG == 32
+	order = fls(size);
+#else
+	order = fls64(size);
+#endif
+	return order;
+}
+
+/**
+ * get_order - Determine the allocation order of a memory size
+ * @size: The size for which to get the order
+ *
+ * Determine the allocation order of a particular sized block of memory.  This
+ * is on a logarithmic scale, where:
+ *
+ *	0 -> 2^0 * PAGE_SIZE and below
+ *	1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
+ *	2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
+ *	3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
+ *	4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
+ *	...
+ *
+ * The order returned is used to find the smallest allocation granule required
+ * to hold an object of the specified size.
+ *
+ * The result is undefined if the size is 0.
+ *
+ * This function may be used to initialise variables with compile time
+ * evaluations of constants.
+ */
+#define get_order(n)						\
+(								\
+	__builtin_constant_p(n) ? (				\
+		((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT :	\
+		(((n) < (1UL << PAGE_SHIFT)) ? 0 :		\
+		 ilog2((n) - 1) - PAGE_SHIFT + 1)		\
+	) :							\
+	__get_order(n)						\
+)
+
+#endif	/* __ASSEMBLY__ */
+
+#endif	/* __ASM_GENERIC_GETORDER_H */