[PATCH v8 1/8] iommu/arm-smmu-v3: Make default domain type of HiSilicon PTT device to identity

[Yicong Yang]

The DMA operations of HiSilicon PTT device can only work properly with
identical mappings. So add a quirk for the device to force the domain
as passthrough.

Acked-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

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 627a3ed5ee8f..7f51823ab63b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2839,6 +2839,26 @@ static int arm_smmu_dev_disable_feature(struct device *dev,
 	}
 }
 
+/*
+ * HiSilicon PCIe tune and trace device can be used to trace TLP headers on the
+ * PCIe link and save the data to memory by DMA. The hardware is restricted to
+ * use identity mapping only.
+ */
+#define IS_HISI_PTT_DEVICE(pdev)	((pdev)->vendor == PCI_VENDOR_ID_HUAWEI && \
+					 (pdev)->device == 0xa12e)
+
+static int arm_smmu_def_domain_type(struct device *dev)
+{
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+
+		if (IS_HISI_PTT_DEVICE(pdev))
+			return IOMMU_DOMAIN_IDENTITY;
+	}
+
+	return 0;
+}
+
 static struct iommu_ops arm_smmu_ops = {
 	.capable		= arm_smmu_capable,
 	.domain_alloc		= arm_smmu_domain_alloc,
@@ -2856,6 +2876,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.sva_unbind		= arm_smmu_sva_unbind,
 	.sva_get_pasid		= arm_smmu_sva_get_pasid,
 	.page_response		= arm_smmu_page_response,
+	.def_domain_type	= arm_smmu_def_domain_type,
 	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 	.owner			= THIS_MODULE,
 	.default_domain_ops = &(const struct iommu_domain_ops) {
-- 
2.24.0