drm/i915/chv: calculate rc6 residency correctly

The register to read cz count is different from vlv. Also
the counts returned from CCK_CTL1 for BSW are (ticks in 30ns - 1).
czcount_30ns of value 1 is a special case for 320Mhz.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80703Suggested-by: Deepak S <deepak.s@linux.intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Tested-by: Guo Jinxian <jinxianx.guo@intel.com>
Reviewed-by: Deepak S <deepak.s@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -2281,7 +2281,7 @@ enum punit_power_well {
 /* Same as Haswell, but 72064 bytes now. */
 #define GEN8_CXT_TOTAL_SIZE		(18 * PAGE_SIZE)
 
-
+#define CHV_CLK_CTL1			0x101100
 #define VLV_CLK_CTL2			0x101104
 #define   CLK_CTL2_CZCOUNT_30NS_SHIFT	28
 

drivers/gpu/drm/i915/i915_sysfs.c

@@ -47,22 +47,45 @@ static u32 calc_residency(struct drm_device *dev, const u32 reg)
 
 	intel_runtime_pm_get(dev_priv);
 
-	/* On VLV, residency time is in CZ units rather than 1.28us */
+	/* On VLV and CHV, residency time is in CZ units rather than 1.28us */
 	if (IS_VALLEYVIEW(dev)) {
-		u32 clkctl2;
+		u32 reg, czcount_30ns;
 
-		clkctl2 = I915_READ(VLV_CLK_CTL2) >>
-			CLK_CTL2_CZCOUNT_30NS_SHIFT;
-		if (!clkctl2) {
-			WARN(!clkctl2, "bogus CZ count value");
+		if (IS_CHERRYVIEW(dev))
+			reg = CHV_CLK_CTL1;
+		else
+			reg = VLV_CLK_CTL2;
+
+		czcount_30ns = I915_READ(reg) >> CLK_CTL2_CZCOUNT_30NS_SHIFT;
+
+		if (!czcount_30ns) {
+			WARN(!czcount_30ns, "bogus CZ count value");
 			ret = 0;
 			goto out;
 		}
-		units = DIV_ROUND_UP_ULL(30ULL * bias, (u64)clkctl2);
+
+		units = 0;
+		div = 1000000ULL;
+
+		if (IS_CHERRYVIEW(dev)) {
+			/* Special case for 320Mhz */
+			if (czcount_30ns == 1) {
+				div = 10000000ULL;
+				units = 3125ULL;
+			} else {
+				/* chv counts are one less */
+				czcount_30ns += 1;
+			}
+		}
+
+		if (units == 0)
+			units = DIV_ROUND_UP_ULL(30ULL * bias,
+						 (u64)czcount_30ns);
+
 		if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)
 			units <<= 8;
 
-		div = 1000000ULL * bias;
+		div = div * bias;
 	}
 
 	raw_time = I915_READ(reg) * units;