PCI: Refactor pci_ioremap_bar() and pci_ioremap_wc_bar()

pci_ioremap_bar() and pci_ioremap_wc_bar() shared similar implementations
but differed in unimportant ways.  Align them by adding a shared helper,
__pci_ioremap_resource().

Upgrade warning message to error level, since it indicates a driver defect.
Remove WARN_ON() from WC path in favor of the error message.

[bhelgaas: commit log, use ioremap() since pci_iomap_range() doesn't add
anything]
Link: https://lore.kernel.org/r/20210713102436.304693-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -206,32 +206,36 @@ int pci_status_get_and_clear_errors(struct pci_dev *pdev)
 EXPORT_SYMBOL_GPL(pci_status_get_and_clear_errors);
 
 #ifdef CONFIG_HAS_IOMEM
-void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar)
+static void __iomem *__pci_ioremap_resource(struct pci_dev *pdev, int bar,
+					    bool write_combine)
 {
 	struct resource *res = &pdev->resource[bar];
+	resource_size_t start = res->start;
+	resource_size_t size = resource_size(res);
 
 	/*
 	 * Make sure the BAR is actually a memory resource, not an IO resource
 	 */
 	if (res->flags & IORESOURCE_UNSET || !(res->flags & IORESOURCE_MEM)) {
-		pci_warn(pdev, "can't ioremap BAR %d: %pR\n", bar, res);
+		pci_err(pdev, "can't ioremap BAR %d: %pR\n", bar, res);
 		return NULL;
 	}
-	return ioremap(res->start, resource_size(res));
+
+	if (write_combine)
+		return ioremap_wc(start, size);
+
+	return ioremap(start, size);
+}
+
+void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar)
+{
+	return __pci_ioremap_resource(pdev, bar, false);
 }
 EXPORT_SYMBOL_GPL(pci_ioremap_bar);
 
 void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar)
 {
-	/*
-	 * Make sure the BAR is actually a memory resource, not an IO resource
-	 */
-	if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) {
-		WARN_ON(1);
-		return NULL;
-	}
-	return ioremap_wc(pci_resource_start(pdev, bar),
-			  pci_resource_len(pdev, bar));
+	return __pci_ioremap_resource(pdev, bar, true);
 }
 EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar);
 #endif