[PATCH 2/2] drm/i915/vlv: use correct units for rc6 residency v2

[Jesse Barnes <jbarnes@virtuousgeek.org>]

We need to use the clock control reg to figure out how many CZ clks are in
30ns and use that as the basis for our RC6 residency calculations.

v2: use ULL everywhere for consistency (Chris)
    factor out bias for clarity (Chris)

References: https://bugs.freedesktop.org/show_bug.cgi?id=69692
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_reg.h   |  3 +++
 drivers/gpu/drm/i915/i915_sysfs.c | 22 ++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cf995bb..6f8d0cf 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1797,6 +1797,9 @@
  */
 #define HSW_CXT_TOTAL_SIZE		(17 * PAGE_SIZE)
 
+#define VLV_CLK_CTL2			0x101104
+#define   CLK_CTL2_CZCOUNT_30NS_SHIFT	28
+
 /*
  * Overlay regs
  */
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index 44f4c1a..8003886 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -37,12 +37,30 @@ static u32 calc_residency(struct drm_device *dev, const u32 reg)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u64 raw_time; /* 32b value may overflow during fixed point math */
+	u64 units = 128ULL, div = 100000ULL, bias = 100ULL;
 
 	if (!intel_enable_rc6(dev))
 		return 0;
 
-	raw_time = I915_READ(reg) * 128ULL;
-	return DIV_ROUND_UP_ULL(raw_time, 100000);
+	/* On VLV, residency time is in CZ units rather than 1.28us */
+	if (IS_VALLEYVIEW(dev)) {
+		u32 clkctl2;
+
+		clkctl2 = I915_READ(VLV_CLK_CTL2) >>
+			CLK_CTL2_CZCOUNT_30NS_SHIFT;
+		if (!clkctl2) {
+			WARN(!clkctl2, "bogus CZ count value");
+			return 0;
+		}
+		units = DIV_ROUND_UP_ULL(30ULL * bias, (u64)clkctl2);
+		if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)
+			units <<= 8;
+
+		div = 1000000ULL * bias;
+	}
+
+	raw_time = I915_READ(reg) * units;
+	return DIV_ROUND_UP_ULL(raw_time, div);
 }
 
 static ssize_t
-- 
1.8.3.1