linux-kernel - [PATCH RFC 2/2] iommu/arm-smmu-v3: Bypass SID0 for NXP i.MX95

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Message-Id: <20241015-smmuv3-v1-2-e4b9ed1b5501@nxp.com>
Date: Tue, 15 Oct 2024 11:14:43 +0800
From: "Peng Fan (OSS)" <peng.fan@....nxp.com>
To: Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>, 
 Joerg Roedel <joro@...tes.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Joy Zou <joy.zou@....com>, linux-arm-kernel@...ts.infradead.org, 
 iommu@...ts.linux.dev, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>, 
 Jason Gunthorpe <jgg@...pe.ca>
Subject: [PATCH RFC 2/2] iommu/arm-smmu-v3: Bypass SID0 for NXP i.MX95

From: Peng Fan <peng.fan@....com>

i.MX95 eDMA3 connects to DSU ACP, supporting dma coherent memory to
memory operations. However TBU is in the path between eDMA3 and ACP,
need to bypass the default SID 0 to make eDMA3 work properly.

Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 19 ++++++++++++++++---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  1 +
 2 files changed, 17 insertions(+), 3 deletions(-)

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 737c5b88235510e3ddb91a28cecbdcdc14854b32..3db7b3e2ac94e16130fc0356f7954ffa1a9dfb33 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -80,6 +80,7 @@ DEFINE_MUTEX(arm_smmu_asid_lock);
 static struct arm_smmu_option_prop arm_smmu_options[] = {
 	{ ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
 	{ ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
+	{ ARM_SMMU_OPT_IMX95_BYPASS_SID0, "nxp,imx95-bypass-sid-zero"},
 	{ 0, NULL},
 };
 
@@ -4465,7 +4466,7 @@ 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)
+static void arm_smmu_install_bypass_ste(struct arm_smmu_device *smmu)
 {
 	struct list_head rmr_list;
 	struct iommu_resv_region *e;
@@ -4496,6 +4497,18 @@ static void arm_smmu_rmr_install_bypass_ste(struct arm_smmu_device *smmu)
 	}
 
 	iort_put_rmr_sids(dev_fwnode(smmu->dev), &rmr_list);
+
+	if (smmu->options & ARM_SMMU_OPT_IMX95_BYPASS_SID0) {
+		int ret = arm_smmu_init_sid_strtab(smmu, 0);
+
+		if (ret) {
+			dev_err(smmu->dev, "i.MX95 SID0 bypass failed\n");
+			return;
+		}
+
+		arm_smmu_make_bypass_ste(smmu,
+					 arm_smmu_get_step_for_sid(smmu, 0));
+	}
 }
 
 static void arm_smmu_impl_remove(void *data)
@@ -4614,8 +4627,8 @@ 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 */
-	arm_smmu_rmr_install_bypass_ste(smmu);
+	/* Install bypass STEs if any */
+	arm_smmu_install_bypass_ste(smmu);
 
 	/* Reset the device */
 	ret = arm_smmu_device_reset(smmu);
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 1e9952ca989f87957197f4d4b400f9d74bb685ac..06481b923284776e7dc4f3301e5cbe8ab7869a9c 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -733,6 +733,7 @@ struct arm_smmu_device {
 #define ARM_SMMU_OPT_MSIPOLL		(1 << 2)
 #define ARM_SMMU_OPT_CMDQ_FORCE_SYNC	(1 << 3)
 #define ARM_SMMU_OPT_TEGRA241_CMDQV	(1 << 4)
+#define ARM_SMMU_OPT_IMX95_BYPASS_SID0	(1 << 5)
 	u32				options;
 
 	struct arm_smmu_cmdq		cmdq;

-- 
2.37.1