drm/i915: Sanity check all registers for matching fw domains

Add a late selftest that walks over all forcewake registers (those below
0x40000) and uses the mmio debug register to check to see if any are
unclaimed. This is possible if we fail to wake the appropriate
powerwells for the register.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-24-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/selftests/intel_uncore.c

@@ -108,6 +108,61 @@ int intel_uncore_mock_selftests(void)
 	return 0;
 }
 
+static int intel_uncore_check_forcewake_domains(struct drm_i915_private *dev_priv)
+{
+#define FW_RANGE 0x40000
+	unsigned long *valid;
+	u32 offset;
+	int err;
+
+	if (!HAS_FPGA_DBG_UNCLAIMED(dev_priv) &&
+	    !IS_VALLEYVIEW(dev_priv) &&
+	    !IS_CHERRYVIEW(dev_priv))
+		return 0;
+
+	if (IS_VALLEYVIEW(dev_priv)) /* XXX system lockup! */
+		return 0;
+
+	if (IS_BROADWELL(dev_priv)) /* XXX random GPU hang afterwards! */
+		return 0;
+
+	valid = kzalloc(BITS_TO_LONGS(FW_RANGE) * sizeof(*valid),
+			GFP_TEMPORARY);
+	if (!valid)
+		return -ENOMEM;
+
+	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+
+	check_for_unclaimed_mmio(dev_priv);
+	for (offset = 0; offset < FW_RANGE; offset += 4) {
+		i915_reg_t reg = { offset };
+
+		(void)I915_READ_FW(reg);
+		if (!check_for_unclaimed_mmio(dev_priv))
+			set_bit(offset, valid);
+	}
+
+	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+
+	err = 0;
+	for_each_set_bit(offset, valid, FW_RANGE) {
+		i915_reg_t reg = { offset };
+
+		intel_uncore_forcewake_reset(dev_priv, false);
+		check_for_unclaimed_mmio(dev_priv);
+
+		(void)I915_READ(reg);
+		if (check_for_unclaimed_mmio(dev_priv)) {
+			pr_err("Unclaimed mmio read to register 0x%04x\n",
+			       offset);
+			err = -EINVAL;
+		}
+	}
+
+	kfree(valid);
+	return err;
+}
+
 int intel_uncore_live_selftests(struct drm_i915_private *i915)
 {
 	int err;
@@ -119,5 +174,9 @@ int intel_uncore_live_selftests(struct drm_i915_private *i915)
 	if (err)
 		return err;
 
+	err = intel_uncore_check_forcewake_domains(i915);
+	if (err)
+		return err;
+
 	return 0;
 }