drm/i915: Add non claimed mmio checking for vlv/chv

Imre mentioned that chv might also have capability to
track unclaimed mmio accesses. Ville added that
both chv and vlv has this capability and he had already
made this way back [1]. Mimic what Ville's patch does
but adapt on top of less frequent mmio accesses by
omitting checking always on reg writes.

This patch is untested as of now.

v2: overflow handling and posting omitted (Ville)

References: [1] http://lists.freedesktop.org/archives/intel-gfx/2013-May/027599.html
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450201542-22918-1-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -1711,6 +1711,11 @@ enum skl_disp_power_wells {
 #define FPGA_DBG		_MMIO(0x42300)
 #define   FPGA_DBG_RM_NOCLAIM	(1<<31)
 
+#define CLAIM_ER		_MMIO(VLV_DISPLAY_BASE + 0x2028)
+#define   CLAIM_ER_CLR		(1 << 31)
+#define   CLAIM_ER_OVERFLOW	(1 << 16)
+#define   CLAIM_ER_CTR_MASK	0xffff
+
 #define DERRMR		_MMIO(0x44050)
 /* Note that HBLANK events are reserved on bdw+ */
 #define   DERRMR_PIPEA_SCANLINE		(1<<0)

drivers/gpu/drm/i915/intel_uncore.c

@@ -328,13 +328,10 @@ static void intel_uncore_ellc_detect(struct drm_device *dev)
 }
 
 static bool
-check_for_unclaimed_mmio(struct drm_i915_private *dev_priv)
+fpga_check_for_unclaimed_mmio(struct drm_i915_private *dev_priv)
 {
 	u32 dbg;
 
-	if (!HAS_FPGA_DBG_UNCLAIMED(dev_priv))
-		return false;
-
 	dbg = __raw_i915_read32(dev_priv, FPGA_DBG);
 	if (likely(!(dbg & FPGA_DBG_RM_NOCLAIM)))
 		return false;
@@ -344,6 +341,32 @@ check_for_unclaimed_mmio(struct drm_i915_private *dev_priv)
 	return true;
 }
 
+static bool
+vlv_check_for_unclaimed_mmio(struct drm_i915_private *dev_priv)
+{
+	u32 cer;
+
+	cer = __raw_i915_read32(dev_priv, CLAIM_ER);
+	if (likely(!(cer & (CLAIM_ER_OVERFLOW | CLAIM_ER_CTR_MASK))))
+		return false;
+
+	__raw_i915_write32(dev_priv, CLAIM_ER, CLAIM_ER_CLR);
+
+	return true;
+}
+
+static bool
+check_for_unclaimed_mmio(struct drm_i915_private *dev_priv)
+{
+	if (HAS_FPGA_DBG_UNCLAIMED(dev_priv))
+		return fpga_check_for_unclaimed_mmio(dev_priv);
+
+	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
+		return vlv_check_for_unclaimed_mmio(dev_priv);
+
+	return false;
+}
+
 static void __intel_uncore_early_sanitize(struct drm_device *dev,
 					  bool restore_forcewake)
 {