[U-Boot] [PATCH v3 1/2] bitops: Add support for order_base_2()

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam at freescale.com>

Add support for the order_base_2() macro (and its dependencies)
from the Linux kernel.

This is useful for the SPI NOR unlock function.

Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
Changes since v2:
- None.
Changes since v1:
- None.

 arch/arm/include/asm/bitops.h | 56 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/arch/arm/include/asm/bitops.h b/arch/arm/include/asm/bitops.h
index 9b78043..b9b6d21 100644
--- a/arch/arm/include/asm/bitops.h
+++ b/arch/arm/include/asm/bitops.h
@@ -108,6 +108,62 @@ static inline int __ilog2(unsigned int x)
 	return generic_fls(x) - 1;
 }
 
+static inline int fls64(__u64 x)
+{
+	if (x == 0)
+		return 0;
+	return generic_fls(x) + 1;
+}
+
+static inline unsigned fls_long(unsigned long l)
+{
+	if (sizeof(l) == 4)
+		return generic_fls(l);
+	return fls64(l);
+}
+
+/*
+ * 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);
+}
+
+/**
+ * roundup_pow_of_two - round the given value up to nearest power of two
+ * @n - parameter
+ *
+ * round the given value 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) ? 1 :			\
+		(1UL << (__ilog2((n) - 1) + 1))	\
+				   ) :		\
+	__roundup_pow_of_two(n)			\
+)
+
+/**
+ * order_base_2 - calculate the (rounded up) base 2 order of the argument
+ * @n: parameter
+ *
+ * The first few values calculated by this routine:
+ *  ob2(0) = 0
+ *  ob2(1) = 0
+ *  ob2(2) = 1
+ *  ob2(3) = 2
+ *  ob2(4) = 2
+ *  ob2(5) = 3
+ *  ... and so on.
+ */
+
+#define order_base_2(n) __ilog2(roundup_pow_of_two(n))
+
 /*
  * ffz = Find First Zero in word. Undefined if no zero exists,
  * so code should check against ~0UL first..
-- 
1.9.1