[PATCH v4 7/8] iommu/arm-smmu: Get associated RMR info and install bypass SMR

[Shameer Kolothum]

From: Jon Nettleton <jon at solid-run.com>

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

Signed-off-by: Jon Nettleton <jon at solid-run.com>
Signed-off-by: Steven Price <steven.price at arm.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/arm/arm-smmu/arm-smmu.c | 64 +++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 6f72c4d208ca..f67aeb30b5ef 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -2042,6 +2042,66 @@ err_reset_platform_ops: __maybe_unused;
 	return err;
 }
 
+static void arm_smmu_rmr_install_bypass_smr(struct arm_smmu_device *smmu)
+{
+	struct list_head rmr_list;
+	struct iommu_rmr *e;
+	int i, cnt = 0;
+	u32 smr;
+	u32 reg;
+
+	INIT_LIST_HEAD(&rmr_list);
+	if (iommu_dma_get_rmrs(dev_fwnode(smmu->dev), &rmr_list))
+		return;
+
+	reg = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_sCR0);
+
+	if ((reg & ARM_SMMU_sCR0_USFCFG) && !(reg & ARM_SMMU_sCR0_CLIENTPD)) {
+		/*
+		 * SMMU is already enabled and disallowing bypass, so preserve
+		 * the existing SMRs
+		 */
+		for (i = 0; i < smmu->num_mapping_groups; i++) {
+			smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i));
+			if (!FIELD_GET(ARM_SMMU_SMR_VALID, smr))
+				continue;
+			smmu->smrs[i].id = FIELD_GET(ARM_SMMU_SMR_ID, smr);
+			smmu->smrs[i].mask = FIELD_GET(ARM_SMMU_SMR_MASK, smr);
+			smmu->smrs[i].valid = true;
+		}
+	}
+
+	list_for_each_entry(e, &rmr_list, list) {
+		u32 sid = e->sid;
+
+		i = arm_smmu_find_sme(smmu, sid, ~0);
+		if (i < 0)
+			continue;
+		if (smmu->s2crs[i].count == 0) {
+			smmu->smrs[i].id = sid;
+			smmu->smrs[i].mask = ~0;
+			smmu->smrs[i].valid = true;
+		}
+		smmu->s2crs[i].count++;
+		smmu->s2crs[i].type = S2CR_TYPE_BYPASS;
+		smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
+		smmu->s2crs[i].cbndx = 0xff;
+
+		cnt++;
+	}
+
+	if ((reg & ARM_SMMU_sCR0_USFCFG) && !(reg & ARM_SMMU_sCR0_CLIENTPD)) {
+		/* Remove the valid bit for unused SMRs */
+		for (i = 0; i < smmu->num_mapping_groups; i++) {
+			if (smmu->s2crs[i].count == 0)
+				smmu->smrs[i].valid = false;
+		}
+	}
+
+	dev_notice(smmu->dev, "\tpreserved %d boot mapping%s\n", cnt,
+		   cnt == 1 ? "" : "s");
+}
+
 static int arm_smmu_device_probe(struct platform_device *pdev)
 {
 	struct resource *res;
@@ -2168,6 +2228,10 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	}
 
 	platform_set_drvdata(pdev, smmu);
+
+	/* Check for RMRs and install bypass SMRs if any */
+	arm_smmu_rmr_install_bypass_smr(smmu);
+
 	arm_smmu_device_reset(smmu);
 	arm_smmu_test_smr_masks(smmu);
 
-- 
2.17.1