of/irq: Create of_irq_parse_and_map_pci() to consolidate arch code.

Several architectures open code effectively the same code block for
finding and mapping PCI irqs. This patch consolidates it down to a
single function.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Michal Simek <monstr@monstr.eu>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/of/of_pci_irq.c b/drivers/of/of_pci_irq.c
index 303afeb..8e92acd 100644
--- a/drivers/of/of_pci_irq.c
+++ b/drivers/of/of_pci_irq.c
@@ -94,3 +94,28 @@
 	return of_irq_parse_raw(laddr, out_irq);
 }
 EXPORT_SYMBOL_GPL(of_irq_parse_pci);
+
+/**
+ * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
+ * @dev: The pci device needing an irq
+ * @slot: PCI slot number; passed when used as map_irq callback. Unused
+ * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
+ *
+ * @slot and @pin are unused, but included in the function so that this
+ * function can be used directly as the map_irq callback to pci_fixup_irqs().
+ */
+int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+	struct of_phandle_args oirq;
+	int ret;
+
+	ret = of_irq_parse_pci(dev, &oirq);
+	if (ret) {
+		dev_err(&dev->dev, "of_irq_parse_pci() failed with rc=%d\n", ret);
+		return 0; /* Proper return code 0 == NO_IRQ */
+	}
+
+	return irq_create_of_mapping(&oirq);
+}
+EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
+