iommu/arm-smmu: Allow client devices to select direct mapping

Some client devices want to directly map the IOMMU themselves instead
of using the DMA domain. Allow those devices to opt in to direct
mapping by way of a list of compatible strings.
Co-developed-by: NSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: NJordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: NSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/7cf1f64167b5545b7f42275395be1f1e2ea3a6ac.1587407458.git.saiprakash.ranjan@codeaurora.orgSigned-off-by: NWill Deacon <will@kernel.org>

drivers/iommu/arm-smmu-qcom.c

@@ -3,6 +3,7 @@
  * Copyright (c) 2019, The Linux Foundation. All rights reserved.
  */
 
+#include <linux/of_device.h>
 #include <linux/qcom_scm.h>
 
 #include "arm-smmu.h"
@@ -11,6 +12,23 @@ struct qcom_smmu {
 	struct arm_smmu_device smmu;
 };
 
+static const struct of_device_id qcom_smmu_client_of_match[] = {
+	{ .compatible = "qcom,adreno" },
+	{ .compatible = "qcom,mdp4" },
+	{ .compatible = "qcom,mdss" },
+	{ .compatible = "qcom,sc7180-mdss" },
+	{ .compatible = "qcom,sdm845-mdss" },
+	{ }
+};
+
+static int qcom_smmu_def_domain_type(struct device *dev)
+{
+	const struct of_device_id *match =
+		of_match_device(qcom_smmu_client_of_match, dev);
+
+	return match ? IOMMU_DOMAIN_IDENTITY : 0;
+}
+
 static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
 {
 	int ret;
@@ -41,6 +59,7 @@ static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
 }
 
 static const struct arm_smmu_impl qcom_smmu_impl = {
+	.def_domain_type = qcom_smmu_def_domain_type,
 	.reset = qcom_smmu500_reset,
 };