1 files changed, 30 insertions, 1 deletions

diff --git a/include/asm-arm/bitops.h b/include/asm-arm/bitops.h
index d02de721ecc1..eaecd553e856 100644
--- a/include/asm-arm/bitops.h
+++ b/include/asm-arm/bitops.h
@@ -344,13 +344,42 @@ static inline unsigned long __ffs(unsigned long word)
 
 #else
 
+static inline int constant_fls(int x)
+{
+        int r = 32;
+
+        if (!x)
+                return 0;
+        if (!(x & 0xffff0000u)) {
+                x <<= 16;
+                r -= 16;
+        }
+        if (!(x & 0xff000000u)) {
+                x <<= 8;
+                r -= 8;
+        }
+        if (!(x & 0xf0000000u)) {
+                x <<= 4;
+                r -= 4;
+        }
+        if (!(x & 0xc0000000u)) {
+                x <<= 2;
+                r -= 2;
+        }
+        if (!(x & 0x80000000u)) {
+                x <<= 1;
+                r -= 1;
+        }
+        return r;
+}
+
 /*
  * On ARMv5 and above those functions can be implemented around
  * the clz instruction for much better code efficiency.
  */
 
 #define fls(x) \
-        ( __builtin_constant_p(x) ? generic_fls(x) : \
+        ( __builtin_constant_p(x) ? constant_fls(x) : \
           ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) )
 #define fls64(x)   generic_fls64(x)
 #define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); })