[PATCH] Fix timeout overflow with jiffies

[linux-2.6-omap-h63xx.git] / include / linux / log2.h

diff --git a/include/linux/log2.h b/include/linux/log2.h
index 3979c60325ffabb9df953ac02bb8e24986608dc2..99922bedfcc90acaef644369aee3d5e126b7d46d 100644 (file)
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -43,6 +43,26 @@ int __ilog2_u64(u64 n)
 }
 #endif
 
+/*
+ *  Determine whether some value is a power of two, where zero is
+ * *not* considered a power of two.
+ */
+
+static inline __attribute__((const))
+bool is_power_of_2(unsigned long n)
+{
+       return (n != 0 && ((n & (n - 1)) == 0));
+}
+
+/*
+ * round up to nearest power of two
+ */
+static inline __attribute__((const))
+unsigned long __roundup_pow_of_two(unsigned long n)
+{
+       return 1UL << fls_long(n - 1);
+}
+
 /**
  * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value
  * @n - parameter
@@ -128,4 +148,21 @@ int __ilog2_u64(u64 n)
        __ilog2_u64(n)                          \
  )
 
+/**
+ * roundup_pow_of_two - round the given value up to nearest power of two
+ * @n - parameter
+ *
+ * round the given balue up to the nearest power of two
+ * - the result is undefined when n == 0
+ * - this can be used to initialise global variables from constant data
+ */
+#define roundup_pow_of_two(n)                  \
+(                                              \
+       __builtin_constant_p(n) ? (             \
+               (n == 1) ? 0 :                  \
+               (1UL << (ilog2((n) - 1) + 1))   \
+                                  ) :          \
+       __roundup_pow_of_two(n)                 \
+ )
+
 #endif /* _LINUX_LOG2_H */