PCI: Update BAR # and window messages

The PCI log messages print the register offsets at some places and BAR
numbers at other places. There is no uniformity in this logging mechanism.
It would be better to print names than register offsets.

Add a helper function that aids in printing more meaningful information
about the BAR numbers like "VF BAR", "ROM", "bridge window", etc.  This
function can be called while printing PCI log messages.

[bhelgaas: fold in Lukas' static array suggestion from
https://lore.kernel.org/all/20211106115831.GA7452@wunner.de/]
Link: https://lore.kernel.org/r/20211106112606.192563-2-puranjay12@gmail.comSigned-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -850,6 +850,66 @@ struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res)
 }
 EXPORT_SYMBOL(pci_find_resource);
 
+/**
+ * pci_resource_name - Return the name of the PCI resource
+ * @dev: PCI device to query
+ * @i: index of the resource
+ *
+ * Return the standard PCI resource (BAR) name according to their index.
+ */
+const char *pci_resource_name(struct pci_dev *dev, unsigned int i)
+{
+	static const char * const bar_name[] = {
+		"BAR 0",
+		"BAR 1",
+		"BAR 2",
+		"BAR 3",
+		"BAR 4",
+		"BAR 5",
+		"ROM",
+#ifdef CONFIG_PCI_IOV
+		"VF BAR 0",
+		"VF BAR 1",
+		"VF BAR 2",
+		"VF BAR 3",
+		"VF BAR 4",
+		"VF BAR 5",
+#endif
+		"bridge window",	/* "io" included in %pR */
+		"bridge window",	/* "mem" included in %pR */
+		"bridge window",	/* "mem pref" included in %pR */
+	};
+	static const char * const cardbus_name[] = {
+		"BAR 1",
+		"unknown",
+		"unknown",
+		"unknown",
+		"unknown",
+		"unknown",
+#ifdef CONFIG_PCI_IOV
+		"unknown",
+		"unknown",
+		"unknown",
+		"unknown",
+		"unknown",
+		"unknown",
+#endif
+		"CardBus bridge window 0",	/* I/O */
+		"CardBus bridge window 1",	/* I/O */
+		"CardBus bridge window 0",	/* mem */
+		"CardBus bridge window 1",	/* mem */
+	};
+
+	if (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS &&
+	    i < ARRAY_SIZE(cardbus_name))
+		return cardbus_name[i];
+
+	if (i < ARRAY_SIZE(bar_name))
+		return bar_name[i];
+
+	return "unknown";
+}
+
 /**
  * pci_wait_for_pending - wait for @mask bit(s) to clear in status word @pos
  * @dev: the PCI device to operate on

drivers/pci/pci.h

@@ -255,6 +255,8 @@ void __pci_bus_assign_resources(const struct pci_bus *bus,
 				struct list_head *fail_head);
 bool pci_bus_clip_resource(struct pci_dev *dev, int idx);
 
+const char *pci_resource_name(struct pci_dev *dev, unsigned int i);
+
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
 void pci_disable_bridge_window(struct pci_dev *dev);
 struct pci_bus *pci_bus_get(struct pci_bus *bus);