[PATCH v3 7/8] iommu/arm-smmu: Provide helper for allocating identity domain

[Bjorn Andersson]

Some platform implementations needs to be able to allocate a domain for
emulating identity mappings using a context bank without translation.
Provide a helper function to allocate such a domain.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---

Changes since v2:
- Extracted from previous arm_smmu_setup_identity() implementation

 drivers/iommu/arm/arm-smmu/arm-smmu.c | 25 +++++++++++++++++++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu.h |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 4c4d302cd747..3c06146dfdb9 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1924,6 +1924,31 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 	return 0;
 }
 
+struct iommu_domain *arm_smmu_alloc_identity_domain(struct arm_smmu_device *smmu)
+{
+	struct iommu_domain *identity;
+	int ret;
+
+	/* Create a IDENTITY domain to use for all inherited streams */
+	identity = arm_smmu_domain_alloc(IOMMU_DOMAIN_IDENTITY);
+	if (!identity) {
+		dev_err(smmu->dev, "failed to create identity domain\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	identity->pgsize_bitmap = smmu->pgsize_bitmap;
+	identity->type = IOMMU_DOMAIN_IDENTITY;
+	identity->ops = &arm_smmu_ops;
+
+	ret = arm_smmu_init_domain_context(identity, smmu, NULL);
+	if (ret < 0) {
+		dev_err(smmu->dev, "failed to initialize identity domain: %d\n", ret);
+		return ERR_PTR(ret);
+	}
+
+	return identity;
+}
+
 struct arm_smmu_match_data {
 	enum arm_smmu_arch_version version;
 	enum arm_smmu_implementation model;
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
index f58164976e74..fbdf3d7ca70d 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
@@ -537,4 +537,6 @@ struct arm_smmu_device *qcom_adreno_smmu_impl_init(struct arm_smmu_device *smmu)
 void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx);
 int arm_mmu500_reset(struct arm_smmu_device *smmu);
 
+struct iommu_domain *arm_smmu_alloc_identity_domain(struct arm_smmu_device *smmu);
+
 #endif /* _ARM_SMMU_H */
-- 
2.28.0