PCI/MSI: Use of_msi_get_domain instead of open-coded "msi-parent" parsing

Now that we have a function that implements the complexity of the
"msi-parent" property parsing, switch to that.

Acked-by: Rob Herring <[e-mail]>
Acked-by: Bjorn Helgaas <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>

drivers/pci/of.c

···
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/of.h>
+#include <linux/of_irq.h>
 #include <linux/of_pci.h>
 #include "pci.h"
 
···
 struct irq_domain *pci_host_bridge_of_msi_domain(struct pci_bus *bus)
 {
 #ifdef CONFIG_IRQ_DOMAIN
-	struct device_node *np;
 	struct irq_domain *d;
 
 	if (!bus->dev.of_node)
 		return NULL;
 
 	/* Start looking for a phandle to an MSI controller. */
-	np = of_parse_phandle(bus->dev.of_node, "msi-parent", 0);
+	d = of_msi_get_domain(&bus->dev, bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
+	if (d)
+		return d;
 
 	/*
 	 * If we don't have an msi-parent property, look for a domain
 	 * directly attached to the host bridge.
 	 */
-	if (!np)
-		np = bus->dev.of_node;
-
-	d = irq_find_matching_host(np, DOMAIN_BUS_PCI_MSI);
+	d = irq_find_matching_host(bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
 	if (d)
 		return d;
 
-	return irq_find_host(np);
+	return irq_find_host(bus->dev.of_node);
 #else
 	return NULL;
 #endif