drm/radeon/kms: add R4XX mc register access helper.

Atombios will use the mc register access helper and R4XX hw have a
bigger mc range than R3XX so add R4XX specific mc register access
helper.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r420.c b/drivers/gpu/drm/radeon/r420.c
index 97426a6..96303f0 100644
--- a/drivers/gpu/drm/radeon/r420.c
+++ b/drivers/gpu/drm/radeon/r420.c
@@ -29,6 +29,7 @@
 #include "drmP.h"
 #include "radeon_reg.h"
 #include "radeon.h"
+#include "r420d.h"
 
 /* r420,r423,rv410 depends on : */
 void r100_pci_gart_disable(struct radeon_device *rdev);
@@ -232,3 +233,19 @@
 	return 0;
 #endif
 }
+
+u32 r420_mc_rreg(struct radeon_device *rdev, u32 reg)
+{
+	u32 r;
+
+	WREG32(R_0001F8_MC_IND_INDEX, S_0001F8_MC_IND_ADDR(reg));
+	r = RREG32(R_0001FC_MC_IND_DATA);
+	return r;
+}
+
+void r420_mc_wreg(struct radeon_device *rdev, u32 reg, u32 v)
+{
+	WREG32(R_0001F8_MC_IND_INDEX, S_0001F8_MC_IND_ADDR(reg) |
+		S_0001F8_MC_IND_WR_EN(1));
+	WREG32(R_0001FC_MC_IND_DATA, v);
+}