PCI: add a new function to map BAR offsets

Add a function to map a given resource number to a corresponding
register so drivers can get the offset and type of device specific BARs.
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.c

@@ -2201,6 +2201,28 @@ int pci_select_bars(struct pci_dev *dev, unsigned long flags)
 	return bars;
 }
 
+/**
+ * pci_resource_bar - get position of the BAR associated with a resource
+ * @dev: the PCI device
+ * @resno: the resource number
+ * @type: the BAR type to be filled in
+ *
+ * Returns BAR position in config space, or 0 if the BAR is invalid.
+ */
+int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type)
+{
+	if (resno < PCI_ROM_RESOURCE) {
+		*type = pci_bar_unknown;
+		return PCI_BASE_ADDRESS_0 + 4 * resno;
+	} else if (resno == PCI_ROM_RESOURCE) {
+		*type = pci_bar_mem32;
+		return dev->rom_base_reg;
+	}
+
+	dev_err(&dev->dev, "BAR: invalid resource #%d\n", resno);
+	return 0;
+}
+
 static void __devinit pci_no_domains(void)
 {
 #ifdef CONFIG_PCI_DOMAINS

drivers/pci/pci.h

@@ -171,6 +171,8 @@ enum pci_bar_type {
 
 extern int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 				struct resource *res, unsigned int reg);
+extern int pci_resource_bar(struct pci_dev *dev, int resno,
+			    enum pci_bar_type *type);
 extern void pci_enable_ari(struct pci_dev *dev);
 /**
  * pci_ari_enabled - query ARI forwarding status

drivers/pci/setup-res.c

@@ -31,6 +31,7 @@ void pci_update_resource(struct pci_dev *dev, int resno)
 	struct pci_bus_region region;
 	u32 new, check, mask;
 	int reg;
+	enum pci_bar_type type;
 	struct resource *res = dev->resource + resno;
 
 	/*
@@ -62,17 +63,13 @@ void pci_update_resource(struct pci_dev *dev, int resno)
 	else
 		mask = (u32)PCI_BASE_ADDRESS_MEM_MASK;
 
-	if (resno < 6) {
-		reg = PCI_BASE_ADDRESS_0 + 4 * resno;
-	} else if (resno == PCI_ROM_RESOURCE) {
+	reg = pci_resource_bar(dev, resno, &type);
+	if (!reg)
+		return;
+	if (type != pci_bar_unknown) {
 		if (!(res->flags & IORESOURCE_ROM_ENABLE))
 			return;
 		new |= PCI_ROM_ADDRESS_ENABLE;
-		reg = dev->rom_base_reg;
-	} else {
-		/* Hmm, non-standard resource. */
-	
-		return;		/* kill uninitialised var warning */
 	}
 
 	pci_write_config_dword(dev, reg, new);