diff --git a/arch/mips/include/asm/addrspace.h b/arch/mips/include/asm/addrspace.h
index c5b04e752e9762f4920d3b305356d9778216ee65..4856adc8906ef3a7c337fe1a14c7e08af426e29e 100644
--- a/arch/mips/include/asm/addrspace.h
+++ b/arch/mips/include/asm/addrspace.h
@@ -126,8 +126,7 @@
 #define PHYS_TO_XKSEG_UNCACHED(p)	PHYS_TO_XKPHYS(K_CALG_UNCACHED, (p))
 #define PHYS_TO_XKSEG_CACHED(p)		PHYS_TO_XKPHYS(K_CALG_COH_SHAREABLE, (p))
 #define XKPHYS_TO_PHYS(p)		((p) & TO_PHYS_MASK)
-#define PHYS_TO_XKPHYS(cm, a)		(_CONST64_(0x8000000000000000) | \
-					 (_CONST64_(cm) << 59) | (a))
+#define PHYS_TO_XKPHYS(cm, a)		(XKPHYS | (_ACAST64_(cm) << 59) | (a))
 
 /*
  * The ultimate limited of the 64-bit MIPS architecture:  2 bits for selecting
diff --git a/arch/mips/include/asm/mach-generic/spaces.h b/arch/mips/include/asm/mach-generic/spaces.h
index afc96ecb90042358685be12d3b2e0f8ab21964ce..952b0fdfda0e637849315f534043137f10972414 100644
--- a/arch/mips/include/asm/mach-generic/spaces.h
+++ b/arch/mips/include/asm/mach-generic/spaces.h
@@ -12,6 +12,8 @@
 
 #include <linux/const.h>
 
+#include <asm/mipsregs.h>
+
 /*
  * This gives the physical RAM offset.
  */
@@ -52,11 +54,7 @@
 #ifdef CONFIG_64BIT
 
 #ifndef CAC_BASE
-#ifdef CONFIG_DMA_NONCOHERENT
-#define CAC_BASE		_AC(0x9800000000000000, UL)
-#else
-#define CAC_BASE		_AC(0xa800000000000000, UL)
-#endif
+#define CAC_BASE	PHYS_TO_XKPHYS(read_c0_config() & CONF_CM_CMASK, 0)
 #endif
 
 #ifndef IO_BASE
diff --git a/arch/mips/include/asm/mach-ip27/spaces.h b/arch/mips/include/asm/mach-ip27/spaces.h
index b18802a0b17e94dca9a85cc6a8a3c761dfb9f60e..4775a1136a5b45eea2359b74bfe530320e95d9df 100644
--- a/arch/mips/include/asm/mach-ip27/spaces.h
+++ b/arch/mips/include/asm/mach-ip27/spaces.h
@@ -19,6 +19,7 @@
 #define IO_BASE			0x9200000000000000
 #define MSPEC_BASE		0x9400000000000000
 #define UNCAC_BASE		0x9600000000000000
+#define CAC_BASE		0xa800000000000000
 
 #define TO_MSPEC(x)		(MSPEC_BASE | ((x) & TO_PHYS_MASK))
 #define TO_HSPEC(x)		(HSPEC_BASE | ((x) & TO_PHYS_MASK))