PCI/P2PDMA: Refactor pci_p2pdma_map_type()

All callers of pci_p2pdma_map_type() have a struct dev_pgmap and a struct
device (of the client doing the DMA transfer). Thus move the conversion to
struct pci_devs for the provider and client into this function.

Link: https://lore.kernel.org/r/20210610160609.28447-6-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/p2pdma.c

@@ -816,12 +816,20 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
 }
 EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
 
-static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct pci_dev *provider,
-						    struct pci_dev *client)
+static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
+						    struct device *dev)
 {
+	struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
+	struct pci_dev *client;
+
 	if (!provider->p2pdma)
 		return PCI_P2PDMA_MAP_NOT_SUPPORTED;
 
+	if (!dev_is_pci(dev))
+		return PCI_P2PDMA_MAP_NOT_SUPPORTED;
+
+	client = to_pci_dev(dev);
+
 	return xa_to_value(xa_load(&provider->p2pdma->map_types,
 				   map_types_idx(client)));
 }
@@ -858,14 +866,8 @@ int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 {
 	struct pci_p2pdma_pagemap *p2p_pgmap =
 		to_p2p_pgmap(sg_page(sg)->pgmap);
-	struct pci_dev *client;
-
-	if (WARN_ON_ONCE(!dev_is_pci(dev)))
-		return 0;
 
-	client = to_pci_dev(dev);
-
-	switch (pci_p2pdma_map_type(p2p_pgmap->provider, client)) {
+	switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) {
 	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
 		return dma_map_sg_attrs(dev, sg, nents, dir, attrs);
 	case PCI_P2PDMA_MAP_BUS_ADDR:
@@ -889,17 +891,9 @@ EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg_attrs);
 void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
 		int nents, enum dma_data_direction dir, unsigned long attrs)
 {
-	struct pci_p2pdma_pagemap *p2p_pgmap =
-		to_p2p_pgmap(sg_page(sg)->pgmap);
 	enum pci_p2pdma_map_type map_type;
-	struct pci_dev *client;
-
-	if (WARN_ON_ONCE(!dev_is_pci(dev)))
-		return;
-
-	client = to_pci_dev(dev);
 
-	map_type = pci_p2pdma_map_type(p2p_pgmap->provider, client);
+	map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev);
 
 	if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE)
 		dma_unmap_sg_attrs(dev, sg, nents, dir, attrs);