drm/i915: extract rps interrupt enable/disable helpers

The VECS enabling required some changes to how rps interrupts are
enabled/disabled since VECS interrupts are handling with the PM
interrupt registers.

But now that the pre/postinstall sequences is identical for all
platforms with rps support (snb, ivb, hsw, vlv) we can also use the
exact same sequence to actually enable the rps interrupts. Strictly
speaking using spinlocks is overkill on snb/ivb & vlv since they have
no VECS ring, but imo that's more than made up by the common code.

Hence this just unifies the vlv code with the snb-hsw code which
matched exactly before the VECS enabling. See

commit eda63ffb906c2fb3b609a0e87aeb63c0f25b9e6b
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Tue May 28 19:22:26 2013 -0700

    drm/i915: Add PM regs to pre/post install

and

commit 4848405cced3b46f4ec7d404b8ed5873171ae10a
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Tue May 28 19:22:27 2013 -0700

    drm/i915: make PM interrupt writes non-destructive

for why the gen6 code (shared between snb, ivb and hsw) needed to be
changed originally.

v3: Improve the commit message to more clearly spell out why we want
to unify the code and what exactly changes.

Cc: Paulo Zanoni <przanoni@gmail.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -3121,13 +3121,10 @@ void valleyview_set_rps(struct drm_device *dev, u8 val)
 	trace_intel_gpu_freq_change(vlv_gpu_freq(dev_priv->mem_freq, val));
 }
 
-
-static void gen6_disable_rps(struct drm_device *dev)
+static void gen6_disable_rps_interrupts(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	I915_WRITE(GEN6_RC_CONTROL, 0);
-	I915_WRITE(GEN6_RPNSWREQ, 1 << 31);
 	I915_WRITE(GEN6_PMINTRMSK, 0xffffffff);
 	I915_WRITE(GEN6_PMIER, I915_READ(GEN6_PMIER) & ~GEN6_PM_RPS_EVENTS);
 	/* Complete PM interrupt masking here doesn't race with the rps work
@@ -3142,23 +3139,23 @@ static void gen6_disable_rps(struct drm_device *dev)
 	I915_WRITE(GEN6_PMIIR, GEN6_PM_RPS_EVENTS);
 }
 
-static void valleyview_disable_rps(struct drm_device *dev)
+static void gen6_disable_rps(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	I915_WRITE(GEN6_RC_CONTROL, 0);
-	I915_WRITE(GEN6_PMINTRMSK, 0xffffffff);
-	I915_WRITE(GEN6_PMIER, 0);
-	/* Complete PM interrupt masking here doesn't race with the rps work
-	 * item again unmasking PM interrupts because that is using a different
-	 * register (PMIMR) to mask PM interrupts. The only risk is in leaving
-	 * stale bits in PMIIR and PMIMR which gen6_enable_rps will clean up. */
+	I915_WRITE(GEN6_RPNSWREQ, 1 << 31);
 
-	spin_lock_irq(&dev_priv->irq_lock);
-	dev_priv->rps.pm_iir = 0;
-	spin_unlock_irq(&dev_priv->irq_lock);
+	gen6_disable_rps_interrupts(dev);
+}
+
+static void valleyview_disable_rps(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	I915_WRITE(GEN6_RC_CONTROL, 0);
 
-	I915_WRITE(GEN6_PMIIR, I915_READ(GEN6_PMIIR));
+	gen6_disable_rps_interrupts(dev);
 
 	if (dev_priv->vlv_pctx) {
 		drm_gem_object_unreference(&dev_priv->vlv_pctx->base);
@@ -3191,6 +3188,21 @@ int intel_enable_rc6(const struct drm_device *dev)
 	return (INTEL_RC6_ENABLE | INTEL_RC6p_ENABLE);
 }
 
+static void gen6_enable_rps_interrupts(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	spin_lock_irq(&dev_priv->irq_lock);
+	/* FIXME: Our interrupt enabling sequence is bonghits.
+	 * dev_priv->rps.pm_iir really should be 0 here. */
+	dev_priv->rps.pm_iir = 0;
+	I915_WRITE(GEN6_PMIMR, I915_READ(GEN6_PMIMR) & ~GEN6_PM_RPS_EVENTS);
+	I915_WRITE(GEN6_PMIIR, GEN6_PM_RPS_EVENTS);
+	spin_unlock_irq(&dev_priv->irq_lock);
+	/* unmask all PM interrupts */
+	I915_WRITE(GEN6_PMINTRMSK, 0);
+}
+
 static void gen6_enable_rps(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3319,15 +3331,7 @@ static void gen6_enable_rps(struct drm_device *dev)
 
 	gen6_set_rps(dev_priv->dev, (gt_perf_status & 0xff00) >> 8);
 
-	spin_lock_irq(&dev_priv->irq_lock);
-	/* FIXME: Our interrupt enabling sequence is bonghits.
-	 * dev_priv->rps.pm_iir really should be 0 here. */
-	dev_priv->rps.pm_iir = 0;
-	I915_WRITE(GEN6_PMIMR, I915_READ(GEN6_PMIMR) & ~GEN6_PM_RPS_EVENTS);
-	I915_WRITE(GEN6_PMIIR, GEN6_PM_RPS_EVENTS);
-	spin_unlock_irq(&dev_priv->irq_lock);
-	/* unmask all PM interrupts */
-	I915_WRITE(GEN6_PMINTRMSK, 0);
+	gen6_enable_rps_interrupts(dev);
 
 	rc6vids = 0;
 	ret = sandybridge_pcode_read(dev_priv, GEN6_PCODE_READ_RC6VIDS, &rc6vids);
@@ -3597,12 +3601,7 @@ static void valleyview_enable_rps(struct drm_device *dev)
 
 	valleyview_set_rps(dev_priv->dev, dev_priv->rps.rpe_delay);
 
-	spin_lock_irq(&dev_priv->irq_lock);
-	WARN_ON(dev_priv->rps.pm_iir != 0);
-	I915_WRITE(GEN6_PMIMR, 0);
-	spin_unlock_irq(&dev_priv->irq_lock);
-	/* enable all PM interrupts */
-	I915_WRITE(GEN6_PMINTRMSK, 0);
+	gen6_enable_rps_interrupts(dev);
 
 	gen6_gt_force_wake_put(dev_priv);
 }