[PATCH v2 3/3] PCI: endpoint: pci-epf-vntb: Implement .get_dma_dev()

When vNTB is used as a PCI endpoint function, the NTB device is backed
by a virtual PCI function. For DMA API allocations and mappings, NTB
clients must use the device that is associated with the IOMMU domain.

Implement ntb_dev_ops->get_dma_dev() for pci-epf-vntb and return the EPC
parent device.

Suggested-by: Frank Li <[email protected]>
Signed-off-by: Koichiro Den <[email protected]>
---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 20a400e83439..e5433404f573 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -1436,6 +1436,14 @@ static int vntb_epf_link_disable(struct ntb_dev *ntb)
 	return 0;
 }
 
+static struct device *vntb_epf_get_dma_dev(struct ntb_dev *ndev)
+{
+	struct epf_ntb *ntb = ntb_ndev(ndev);
+	struct pci_epc *epc = ntb->epf->epc;
+
+	return epc->dev.parent;
+}
+
 static const struct ntb_dev_ops vntb_epf_ops = {
 	.mw_count		= vntb_epf_mw_count,
 	.spad_count		= vntb_epf_spad_count,
@@ -1457,6 +1465,7 @@ static const struct ntb_dev_ops vntb_epf_ops = {
 	.db_clear_mask		= vntb_epf_db_clear_mask,
 	.db_clear		= vntb_epf_db_clear,
 	.link_disable		= vntb_epf_link_disable,
+	.get_dma_dev		= vntb_epf_get_dma_dev,
 };
 
 static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
-- 
2.51.0