[ARM] 4982/1: [AT91] Drop old-style UART initialization (Part 1)

[linux-2.6-omap-h63xx.git] / include / asm-arm / byteorder.h

diff --git a/include/asm-arm/byteorder.h b/include/asm-arm/byteorder.h
index 741f5bc5d016ea5888eb95290d909fc2c027a32f..e6f7fcdc73b0299524b1e3b6a6b83eb9f360424f 100644 (file)
--- a/include/asm-arm/byteorder.h
+++ b/include/asm-arm/byteorder.h
@@ -22,7 +22,18 @@ static inline __attribute_const__ __u32 ___arch__swab32(__u32 x)
 {
        __u32 t;
 
-       t = x ^ ((x << 16) | (x >> 16));        /* eor r1,r0,r0,ror #16  */
+#ifndef __thumb__
+       if (!__builtin_constant_p(x)) {
+               /*
+                * The compiler needs a bit of a hint here to always do the
+                * right thing and not screw it up to different degrees
+                * depending on the gcc version.
+                */
+               asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
+       } else
+#endif
+               t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
+
        x = (x << 24) | (x >> 8);               /* mov r0,r0,ror #8      */
        t &= ~0x00FF0000;                       /* bic r1,r1,#0x00FF0000 */
        x ^= (t >> 8);                          /* eor r0,r0,r1,lsr #8   */