drm/i915: BIOS and power context stolen mem handling for VLV v7

But we need to get the right stolen base and make pre-allocated objects
for BIOS stuff so we don't clobber it.  If the BIOS hasn't allocated a
power context, we allocate one here too, from stolen space as required
by the docs.

v2: fix stolen to phys if ladder (Ben)
    keep BIOS reserved space out of allocator altogether (Ben)
v3: fix mask of stolen base (Ben)
v4: clean up preallocated object on unload (Ben)
    don't zero reg on unload (Jesse)
    fix mask harder (Jesse)
v5: use unref for freeing stolen bits (Chris)
    move alloc/free to intel_pm.c (Chris)
v6: NULL pctx at disable time so error paths work (Ben)
v7: use correct PCI device for config read (Jesse)

Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7d35f43..67294f4 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2566,6 +2566,11 @@
 	spin_unlock_irq(&dev_priv->rps.lock);
 
 	I915_WRITE(GEN6_PMIIR, I915_READ(GEN6_PMIIR));
+
+	if (dev_priv->vlv_pctx) {
+		drm_gem_object_unreference(&dev_priv->vlv_pctx->base);
+		dev_priv->vlv_pctx = NULL;
+	}
 }
 
 int intel_enable_rc6(const struct drm_device *dev)
@@ -2860,6 +2865,48 @@
 	mutex_unlock(&dev_priv->rps.hw_lock);
 }
 
+static void valleyview_setup_pctx(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *pctx;
+	unsigned long pctx_paddr;
+	u32 pcbr;
+	int pctx_size = 24*1024;
+
+	pcbr = I915_READ(VLV_PCBR);
+	if (pcbr) {
+		/* BIOS set it up already, grab the pre-alloc'd space */
+		int pcbr_offset;
+
+		pcbr_offset = (pcbr & (~4095)) - dev_priv->mm.stolen_base;
+		pctx = i915_gem_object_create_stolen_for_preallocated(dev_priv->dev,
+								      pcbr_offset,
+								      pcbr_offset,
+								      pctx_size);
+		goto out;
+	}
+
+	/*
+	 * From the Gunit register HAS:
+	 * The Gfx driver is expected to program this register and ensure
+	 * proper allocation within Gfx stolen memory.  For example, this
+	 * register should be programmed such than the PCBR range does not
+	 * overlap with other ranges, such as the frame buffer, protected
+	 * memory, or any other relevant ranges.
+	 */
+	pctx = i915_gem_object_create_stolen(dev, pctx_size);
+	if (!pctx) {
+		DRM_DEBUG("not enough stolen space for PCTX, disabling\n");
+		return;
+	}
+
+	pctx_paddr = dev_priv->mm.stolen_base + pctx->stolen->start;
+	I915_WRITE(VLV_PCBR, pctx_paddr);
+
+out:
+	dev_priv->vlv_pctx = pctx;
+}
+
 static void valleyview_enable_rps(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -2874,6 +2921,8 @@
 		I915_WRITE(GTFIFODBG, gtfifodbg);
 	}
 
+	valleyview_setup_pctx(dev);
+
 	gen6_gt_force_wake_get(dev_priv);
 
 	I915_WRITE(GEN6_RP_UP_THRESHOLD, 59400);