[MIPS] IP28: switch to "normal" mode after PROM no longer needed

SGI-IP28 is running in so called slow mode, when kernel is started
from the PROM. PROM calls must be done in slow mode otherwise the
PROM will issue an error. To get better memory performance we now
switch to normal mode, when the PROM is no longer needed.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/asm-mips/barrier.h b/include/asm-mips/barrier.h
index 9d8cfbb5e796..8e9ac313ca3b 100644
--- a/include/asm-mips/barrier.h
+++ b/include/asm-mips/barrier.h
@@ -92,11 +92,25 @@
 #define fast_wmb()      __sync()
 #define fast_rmb()      __sync()
 #define fast_mb()       __sync()
+#ifdef CONFIG_SGI_IP28
+#define fast_iob()                              \
+        __asm__ __volatile__(                   \
+                ".set   push\n\t"               \
+                ".set   noreorder\n\t"          \
+                "lw     $0,%0\n\t"              \
+                "sync\n\t"                      \
+                "lw     $0,%0\n\t"              \
+                ".set   pop"                    \
+                : /* no output */               \
+                : "m" (*(int *)CKSEG1ADDR(0x1fa00004)) \
+                : "memory")
+#else
 #define fast_iob()                              \
         do {                                    \
                 __sync();                       \
                 __fast_iob();                   \
         } while (0)
+#endif
 
 #ifdef CONFIG_CPU_HAS_WB