PCI: Add pci_add_dma_alias() to abstract implementation

Add a pci_add_dma_alias() interface to encapsulate the details of adding an
alias.  No functional change intended.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>

drivers/pci/pci.c

@@ -4578,6 +4578,20 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
 	return 0;
 }
 
+/**
+ * pci_add_dma_alias - Add a DMA devfn alias for a device
+ * @dev: the PCI device for which alias is added
+ * @devfn: alias slot and function
+ *
+ * This helper encodes 8-bit devfn as bit number in dma_alias_mask.
+ * It should be called early, preferably as PCI fixup header quirk.
+ */
+void pci_add_dma_alias(struct pci_dev *dev, u8 devfn)
+{
+	dev->dma_alias_devfn = devfn;
+	dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN;
+}
+
 bool pci_device_is_present(struct pci_dev *pdev)
 {
 	u32 v;

drivers/pci/quirks.c

@@ -3610,10 +3610,8 @@ int pci_dev_specific_reset(struct pci_dev *dev, int probe)
 
 static void quirk_dma_func0_alias(struct pci_dev *dev)
 {
-	if (PCI_FUNC(dev->devfn) != 0) {
-		dev->dma_alias_devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 0);
-		dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN;
-	}
+	if (PCI_FUNC(dev->devfn) != 0)
+		pci_add_dma_alias(dev, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
 }
 
 /*
@@ -3626,10 +3624,8 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_RICOH, 0xe476, quirk_dma_func0_alias);
 
 static void quirk_dma_func1_alias(struct pci_dev *dev)
 {
-	if (PCI_FUNC(dev->devfn) != 1) {
-		dev->dma_alias_devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 1);
-		dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN;
-	}
+	if (PCI_FUNC(dev->devfn) != 1)
+		pci_add_dma_alias(dev, PCI_DEVFN(PCI_SLOT(dev->devfn), 1));
 }
 
 /*
@@ -3696,11 +3692,10 @@ static void quirk_fixed_dma_alias(struct pci_dev *dev)
 
 	id = pci_match_id(fixed_dma_alias_tbl, dev);
 	if (id) {
-		dev->dma_alias_devfn = id->driver_data;
-		dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN;
+		pci_add_dma_alias(dev, id->driver_data);
 		dev_info(&dev->dev, "Enabling fixed DMA alias to %02x.%d\n",
-			 PCI_SLOT(dev->dma_alias_devfn),
-			 PCI_FUNC(dev->dma_alias_devfn));
+			 PCI_SLOT(id->driver_data),
+			 PCI_FUNC(id->driver_data));
 	}
 }
 

include/linux/pci.h

@@ -1988,6 +1988,7 @@ static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
 }
 #endif
 
+void pci_add_dma_alias(struct pci_dev *dev, u8 devfn);
 int pci_for_each_dma_alias(struct pci_dev *pdev,
 			   int (*fn)(struct pci_dev *pdev,
 				     u16 alias, void *data), void *data);