linux-kernel - [PATCH] iommu: arm-smmu-impl: add NXP hook to preserve bootmappings

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Date:   Wed, 25 Nov 2020 17:50:09 +0200
From:   laurentiu.tudor@....com
To:     will@...nel.org, robin.murphy@....com, joro@...tes.org,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Cc:     diana.craciun@....com, Laurentiu Tudor <laurentiu.tudor@....com>
Subject: [PATCH] iommu: arm-smmu-impl: add NXP hook to preserve bootmappings

From: Laurentiu Tudor <laurentiu.tudor@....com>

Add a NXP specific hook to preserve SMMU mappings present at
boot time (created by the boot loader). These are needed for
MC firmware present on some NXP chips to continue working
across kernel boot and SMMU initialization.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@....com>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 33 ++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
index 7fed89c9d18a..ca07d9d4be69 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
@@ -187,6 +187,36 @@ static const struct arm_smmu_impl mrvl_mmu500_impl = {
 	.reset = arm_mmu500_reset,
 };
 
+static int nxp_cfg_probe(struct arm_smmu_device *smmu)
+{
+	int i, cnt = 0;
+	u32 smr;
+
+	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)) {
+			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;
+
+			smmu->s2crs[i].type = S2CR_TYPE_BYPASS;
+			smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
+			smmu->s2crs[i].cbndx = 0xff;
+
+			cnt++;
+		}
+	}
+
+	dev_notice(smmu->dev, "\tpreserved %d boot mapping%s\n", cnt,
+		   cnt == 1 ? "" : "s");
+
+	return 0;
+}
+
+static const struct arm_smmu_impl nxp_impl = {
+	.cfg_probe = nxp_cfg_probe,
+};
 
 struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 {
@@ -226,5 +256,8 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 	if (of_device_is_compatible(np, "marvell,ap806-smmu-500"))
 		smmu->impl = &mrvl_mmu500_impl;
 
+	if (of_property_read_bool(np, "nxp,keep-boot-mappings"))
+		smmu->impl = &nxp_impl;
+
 	return smmu;
 }
-- 
2.17.1