[PATCH v9 11/11] 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 | 52 +++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 9a5b785d28fd..d1d0473b8b88 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -2068,6 +2068,54 @@ 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_resv_region *e;
+	int idx, cnt = 0;
+	u32 reg;
+
+	INIT_LIST_HEAD(&rmr_list);
+	iort_get_rmr_sids(dev_fwnode(smmu->dev), &rmr_list);
+
+	/*
+	 * Rather than trying to look at existing mappings that
+	 * are setup by the firmware and then invalidate the ones
+	 * that do no have matching RMR entries, just disable the
+	 * SMMU until it gets enabled again in the reset routine.
+	 */
+	reg = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_sCR0);
+	reg |= ARM_SMMU_sCR0_CLIENTPD;
+	arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_sCR0, reg);
+
+	list_for_each_entry(e, &rmr_list, list) {
+		const u32 *sids = e->fw_data.rmr.sids;
+		u32 num_sids = e->fw_data.rmr.num_sids;
+		int i;
+
+		for (i = 0; i < num_sids; i++) {
+			idx = arm_smmu_find_sme(smmu, sids[i], ~0);
+			if (idx < 0)
+				continue;
+
+			if (smmu->s2crs[idx].count == 0) {
+				smmu->smrs[idx].id = sids[i];
+				smmu->smrs[idx].mask = 0;
+				smmu->smrs[idx].valid = true;
+			}
+			smmu->s2crs[idx].count++;
+			smmu->s2crs[idx].type = S2CR_TYPE_BYPASS;
+			smmu->s2crs[idx].privcfg = S2CR_PRIVCFG_DEFAULT;
+
+			cnt++;
+		}
+	}
+
+	dev_notice(smmu->dev, "\tpreserved %d boot mapping%s\n", cnt,
+		   cnt == 1 ? "" : "s");
+	iort_put_rmr_sids(dev_fwnode(smmu->dev), &rmr_list);
+}
+
 static int arm_smmu_device_probe(struct platform_device *pdev)
 {
 	struct resource *res;
@@ -2189,6 +2237,10 @@ 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);
 
-- 
2.25.1