[MIPS] IP28 support

Add support for SGI IP28 machines (Indigo 2 with R10k CPUs)
This work is mainly based on Peter Fuersts work.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/dma.h b/include/asm-mips/dma.h
index d6a6c21..1353c81 100644
--- a/include/asm-mips/dma.h
+++ b/include/asm-mips/dma.h
@@ -84,10 +84,9 @@
  * Deskstations or Acer PICA but not the much more versatile DMA logic used
  * for the local devices on Acer PICA or Magnums.
  */
-#ifdef CONFIG_SGI_IP22
-/* Horrible hack to have a correct DMA window on IP22 */
-#include <asm/sgi/mc.h>
-#define MAX_DMA_ADDRESS		(PAGE_OFFSET + SGIMC_SEG0_BADDR + 0x01000000)
+#if defined(CONFIG_SGI_IP22) || defined(CONFIG_SGI_IP28)
+/* don't care; ISA bus master won't work, ISA slave DMA supports 32bit addr */
+#define MAX_DMA_ADDRESS		PAGE_OFFSET
 #else
 #define MAX_DMA_ADDRESS		(PAGE_OFFSET + 0x01000000)
 #endif