drm/i915: Set up fence registers on sandybridge.

Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index eff8d85..1232229 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -235,6 +235,9 @@
 #define   I965_FENCE_REG_VALID		(1<<0)
 #define   I965_FENCE_MAX_PITCH_VAL	0x0400
 
+#define FENCE_REG_SANDYBRIDGE_0		0x100000
+#define   SANDYBRIDGE_FENCE_PITCH_SHIFT	32
+
 /*
  * Instruction and interrupt control regs
  */