MIPS: Join the coherent domain when a CM is present

MIPS Linux expects the bootloader to leave the boot CPU a member of the
coherent domain when running on a system with a CM, and we will need to
do so if we wish to make use of IOCUs to have cache-coherent DMA in
U-Boot (and on some systems there is no choice in that matter). When a
CM is present, join the coherent domain after completing cache
initialisation.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
diff --git a/arch/mips/include/asm/cm.h b/arch/mips/include/asm/cm.h
index 62ecef2..b9ab0c6 100644
--- a/arch/mips/include/asm/cm.h
+++ b/arch/mips/include/asm/cm.h
@@ -19,6 +19,7 @@
 #define GCR_L2_TAG_STATE_UPPER		0x060c
 #define GCR_L2_DATA			0x0610
 #define GCR_L2_DATA_UPPER		0x0614
+#define GCR_Cx_COHERENCE		0x2008
 
 /* GCR_REV CM versions */
 #define GCR_REV_CM3			0x0800
@@ -32,6 +33,10 @@
 #define GCR_L2_CONFIG_SETSZ_BITS	4
 #define GCR_L2_CONFIG_BYPASS		(1 << 20)
 
+/* GCR_Cx_COHERENCE */
+#define GCR_Cx_COHERENCE_DOM_EN		(0xff << 0)
+#define GCR_Cx_COHERENCE_EN		(0x1 << 0)
+
 #ifndef __ASSEMBLY__
 
 #include <asm/io.h>