[RFC PATCH v2 7/8] iommu/arm-smmu-v3: Get associated RMR info and install bypass STE

[Shameer Kolothum]

Check if there is any RMR info associated with the devices behind
the SMMUv3 and if any, install bypass STEs for them. This is to
keep any ongoing traffic associated with these devices alive
when we enable/reset SMMUv3 during probe().

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 40 +++++++++++++++++++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  2 ++
 2 files changed, 42 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 5f366d5a9ebf..97df1df001c9 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3486,6 +3486,42 @@ static void __iomem *arm_smmu_ioremap(struct device *dev, resource_size_t start,
 	return devm_ioremap_resource(dev, &res);
 }
 
+static void arm_smmu_rmr_install_bypass_ste(struct arm_smmu_device *smmu)
+{
+	struct iommu_rmr *e;
+	int i, ret;
+
+	/*
+	 * Since, we don't have a mechanism to differentiate the RMR
+	 * SIDs that has an ongoing live stream, install bypass STEs
+	 * for all the reported ones. 
+	 * FixMe: Avoid duplicate SIDs in the list as one sid may
+	 *        associate with multiple RMRs.
+	 */
+	list_for_each_entry(e, &smmu->rmr_list, list) {
+		for (i = 0; i < e->num_ids; i++) {
+			__le64 *step;
+			u32 sid = e->ids[i];
+
+			ret = arm_smmu_init_sid_strtab(smmu, sid);
+			if (ret) {
+				dev_err(smmu->dev, "RMR bypass(0x%x) failed\n",
+					sid);
+				continue;
+			}
+
+			step = arm_smmu_get_step_for_sid(smmu, sid);
+			arm_smmu_write_strtab_ent(NULL, sid, step, true);
+		}
+	}
+}
+
+static int arm_smmu_get_rmr(struct arm_smmu_device *smmu)
+{
+	INIT_LIST_HEAD(&smmu->rmr_list);
+	return iommu_dma_get_rmrs(dev_fwnode(smmu->dev), &smmu->rmr_list);
+}
+
 static int arm_smmu_device_probe(struct platform_device *pdev)
 {
 	int irq, ret;
@@ -3569,6 +3605,10 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	/* Record our private device structure */
 	platform_set_drvdata(pdev, smmu);
 
+	/* Check for RMRs and install bypass STEs if any */
+	if (!arm_smmu_get_rmr(smmu))
+		arm_smmu_rmr_install_bypass_ste(smmu);
+
 	/* Reset the device */
 	ret = arm_smmu_device_reset(smmu, bypass);
 	if (ret)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index d4b7f40ccb02..17b517ddecee 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -636,6 +636,8 @@ struct arm_smmu_device {
 
 	/* IOMMU core code handle */
 	struct iommu_device		iommu;
+
+	struct list_head		rmr_list;
 };
 
 /* SMMU private data for each master */
-- 
2.17.1