diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eada25f..9a8aef7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -113,10 +113,10 @@ struct opregion_swsci;
 struct opregion_asle;
 
 struct intel_opregion {
-	struct opregion_header *header;
-	struct opregion_acpi *acpi;
-	struct opregion_swsci *swsci;
-	struct opregion_asle *asle;
+	struct opregion_header __iomem *header;
+	struct opregion_acpi __iomem *acpi;
+	struct opregion_swsci __iomem *swsci;
+	struct opregion_asle __iomem *asle;
 	int enabled;
 };
 
diff --git a/drivers/gpu/drm/i915/i915_opregion.c b/drivers/gpu/drm/i915/i915_opregion.c
index 7cc8410..743ebe6 100644
--- a/drivers/gpu/drm/i915/i915_opregion.c
+++ b/drivers/gpu/drm/i915/i915_opregion.c
@@ -150,7 +150,7 @@ struct opregion_asle {
 static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
+	struct opregion_asle __iomem *asle = dev_priv->opregion.asle;
 	u32 blc_pwm_ctl, blc_pwm_ctl2;
 	u32 max_backlight, level, shift;
 
@@ -181,7 +181,7 @@ static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 		level = (bclp * max_backlight) / 255;
 		I915_WRITE(BLC_PWM_CTL, blc_pwm_ctl | (level << shift));
 	}
-	asle->cblv = (bclp*0x64)/0xff | ASLE_CBLV_VALID;
+	iowrite32((bclp*0x64)/0xff | ASLE_CBLV_VALID, &asle->cblv);
 
 	return 0;
 }
@@ -218,39 +218,38 @@ static u32 asle_set_pfit(struct drm_device *dev, u32 pfit)
 void opregion_asle_intr(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
+	struct opregion_asle __iomem *asle = dev_priv->opregion.asle;
 	u32 asle_stat = 0;
 	u32 asle_req;
 
 	if (!asle)
 		return;
 
-	asle_req = asle->aslc & ASLE_REQ_MSK;
-
+	asle_req = ioread32(&asle->aslc) & ASLE_REQ_MSK;
 	if (!asle_req) {
 		DRM_DEBUG_DRIVER("non asle set request??\n");
 		return;
 	}
 
 	if (asle_req & ASLE_SET_ALS_ILLUM)
-		asle_stat |= asle_set_als_illum(dev, asle->alsi);
+		asle_stat |= asle_set_als_illum(dev, ioread32(&asle->alsi));
 
 	if (asle_req & ASLE_SET_BACKLIGHT)
-		asle_stat |= asle_set_backlight(dev, asle->bclp);
+		asle_stat |= asle_set_backlight(dev, ioread32(&asle->bclp));
 
 	if (asle_req & ASLE_SET_PFIT)
-		asle_stat |= asle_set_pfit(dev, asle->pfit);
+		asle_stat |= asle_set_pfit(dev, ioread32(&asle->pfit));
 
 	if (asle_req & ASLE_SET_PWM_FREQ)
-		asle_stat |= asle_set_pwm_freq(dev, asle->pfmb);
+		asle_stat |= asle_set_pwm_freq(dev, ioread32(&asle->pfmb));
 
-	asle->aslc = asle_stat;
+	iowrite32(asle_stat, &asle->aslc);
 }
 
 static u32 asle_set_backlight_ironlake(struct drm_device *dev, u32 bclp)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
+	struct opregion_asle __iomem *asle = dev_priv->opregion.asle;
 	u32 cpu_pwm_ctl, pch_pwm_ctl2;
 	u32 max_backlight, level;
 
@@ -272,7 +271,7 @@ static u32 asle_set_backlight_ironlake(struct drm_device *dev, u32 bclp)
 	/* write the updated PWM frequency */
 	I915_WRITE(BLC_PWM_CPU_CTL, cpu_pwm_ctl | level);
 
-	asle->cblv = (bclp*0x64)/0xff | ASLE_CBLV_VALID;
+	iowrite32((bclp*0x64)/0xff | ASLE_CBLV_VALID, &asle->cblv);
 
 	return 0;
 }
@@ -280,15 +279,14 @@ static u32 asle_set_backlight_ironlake(struct drm_device *dev, u32 bclp)
 void ironlake_opregion_gse_intr(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
+	struct opregion_asle __iomem *asle = dev_priv->opregion.asle;
 	u32 asle_stat = 0;
 	u32 asle_req;
 
 	if (!asle)
 		return;
 
-	asle_req = asle->aslc & ASLE_REQ_MSK;
-
+	asle_req = ioread32(&asle->aslc) & ASLE_REQ_MSK;
 	if (!asle_req) {
 		DRM_DEBUG_DRIVER("non asle set request??\n");
 		return;
@@ -300,7 +298,7 @@ void ironlake_opregion_gse_intr(struct drm_device *dev)
 	}
 
 	if (asle_req & ASLE_SET_BACKLIGHT)
-		asle_stat |= asle_set_backlight_ironlake(dev, asle->bclp);
+		asle_stat |= asle_set_backlight_ironlake(dev, ioread32(&asle->bclp));
 
 	if (asle_req & ASLE_SET_PFIT) {
 		DRM_DEBUG_DRIVER("Pfit is not supported\n");
@@ -312,7 +310,7 @@ void ironlake_opregion_gse_intr(struct drm_device *dev)
 		asle_stat |= ASLE_PWM_FREQ_FAILED;
 	}
 
-	asle->aslc = asle_stat;
+	iowrite32(asle_stat, &asle->aslc);
 }
 #define ASLE_ALS_EN    (1<<0)
 #define ASLE_BLC_EN    (1<<1)
@@ -322,7 +320,7 @@ void ironlake_opregion_gse_intr(struct drm_device *dev)
 void opregion_enable_asle(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct opregion_asle *asle = dev_priv->opregion.asle;
+	struct opregion_asle __iomem *asle = dev_priv->opregion.asle;
 
 	if (asle) {
 		if (IS_MOBILE(dev)) {
@@ -334,9 +332,9 @@ void opregion_enable_asle(struct drm_device *dev)
 					       irqflags);
 		}
 
-		asle->tche = ASLE_ALS_EN | ASLE_BLC_EN | ASLE_PFIT_EN |
-			ASLE_PFMB_EN;
-		asle->ardy = 1;
+		iowrite32(ASLE_ALS_EN | ASLE_BLC_EN | ASLE_PFIT_EN | ASLE_PFMB_EN,
+			  &asle->tche);
+		iowrite32(1, &asle->ardy);
 	}
 }
 
@@ -356,13 +354,13 @@ static int intel_opregion_video_event(struct notifier_block *nb,
 	   future, but right now we just indicate to the firmware that the
 	   request has been handled */
 
-	struct opregion_acpi *acpi;
+	struct opregion_acpi __iomem *acpi;
 
 	if (!system_opregion)
 		return NOTIFY_DONE;
 
 	acpi = system_opregion->acpi;
-	acpi->csts = 0;
+	iowrite32(0, &acpi->csts);
 
 	return NOTIFY_OK;
 }
@@ -413,20 +411,35 @@ static void intel_didl_outputs(struct drm_device *dev)
 			output_type = ACPI_LVDS_OUTPUT;
 			break;
 		}
-		opregion->acpi->didl[i] |= (1<<31) | output_type | i;
+		iowrite32(ioread32(&opregion->acpi->didl[i]) |
+			  (1<<31) |
+			  output_type |
+			  i,
+			  &opregion->acpi->didl[i]);
 		i++;
 	}
 
-	/* If fewer than 8 outputs, the list must be null terminated */
+	/* If fewer than 8 outputs, the list must be nul terminated */
 	if (i < 8)
-		opregion->acpi->didl[i] = 0;
+		iowrite32(0, &opregion->acpi->didl[i]);
+}
+
+static bool
+is_opregion_signature(u8 __iomem *sig)
+{
+	int i;
+
+	for (i = 0; i < 16; i++)
+		if (ioread8(sig + i) != OPREGION_SIGNATURE[i])
+			return false;
+	return true;
 }
 
 int intel_opregion_init(struct drm_device *dev, int resume)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_opregion *opregion = &dev_priv->opregion;
-	void *base;
+	void __iomem *base;
 	u32 asls, mboxes;
 	int err = 0;
 
@@ -442,13 +455,13 @@ int intel_opregion_init(struct drm_device *dev, int resume)
 		return -ENOMEM;
 
 	opregion->header = base;
-	if (memcmp(opregion->header->signature, OPREGION_SIGNATURE, 16)) {
+	if (!is_opregion_signature(opregion->header->signature)) {
 		DRM_DEBUG_DRIVER("opregion signature mismatch\n");
 		err = -EINVAL;
 		goto err_out;
 	}
 
-	mboxes = opregion->header->mboxes;
+	mboxes = ioread32(&opregion->header->mboxes);
 	if (mboxes & MBOX_ACPI) {
 		DRM_DEBUG_DRIVER("Public ACPI methods supported\n");
 		opregion->acpi = base + OPREGION_ACPI_OFFSET;
@@ -478,8 +491,8 @@ int intel_opregion_init(struct drm_device *dev, int resume)
 	/* Notify BIOS we are ready to handle ACPI video ext notifs.
 	 * Right now, all the events are handled by the ACPI video module.
 	 * We don't actually need to do anything with them. */
-	opregion->acpi->csts = 0;
-	opregion->acpi->drdy = 1;
+	iowrite32(0, &opregion->acpi->csts);
+	iowrite32(1, &opregion->acpi->drdy);
 
 	system_opregion = opregion;
 	register_acpi_notifier(&intel_opregion_notifier);
@@ -503,7 +516,7 @@ void intel_opregion_free(struct drm_device *dev, int suspend)
 	if (!suspend)
 		acpi_video_unregister();
 
-	opregion->acpi->drdy = 0;
+	iowrite32(0, &opregion->acpi->drdy);
 
 	system_opregion = NULL;
 	unregister_acpi_notifier(&intel_opregion_notifier);
