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

From: Peng Fan (OSS)
Date: Mon Oct 14 2024 - 23:06:49 EST


From: Peng Fan <peng.fan@xxxxxxx>

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@xxxxxxx>
---
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