introduce lower_32_bits() macro

The file kernel.h contains the upper_32_bits macro.  This patch adds the
other part, the lower_32_bits macro.  Its first use will be in the driver
for AMD IOMMU.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index fdbbf72ca2ebfbe096171a7b96dbaf539f7fbcbe..aaa998f65c7af93e8a0e715e5bef0ca5ef067ece 100644 (file)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -75,6 +75,12 @@ extern const char linux_proc_banner[];
  */
 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 
+/**
+ * lower_32_bits - return bits 0-31 of a number
+ * @n: the number we're accessing
+ */
+#define lower_32_bits(n) ((u32)(n))
+
 #define        KERN_EMERG      "<0>"   /* system is unusable                   */
 #define        KERN_ALERT      "<1>"   /* action must be taken immediately     */
 #define        KERN_CRIT       "<2>"   /* critical conditions                  */