1 files changed, 29 insertions, 0 deletions

diff --git a/kernel/drivers/pci/of.c b/kernel/drivers/pci/of.c
index f0929934b..e112da116 100644
--- a/kernel/drivers/pci/of.c
+++ b/kernel/drivers/pci/of.c
@@ -9,9 +9,11 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#include <linux/irqdomain.h>
 #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"
 
@@ -59,3 +61,30 @@ struct device_node * __weak pcibios_get_phb_of_node(struct pci_bus *bus)
 		return of_node_get(bus->bridge->parent->of_node);
 	return NULL;
 }
+
+struct irq_domain *pci_host_bridge_of_msi_domain(struct pci_bus *bus)
+{
+#ifdef CONFIG_IRQ_DOMAIN
+	struct irq_domain *d;
+
+	if (!bus->dev.of_node)
+		return NULL;
+
+	/* Start looking for a phandle to an MSI controller. */
+	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.
+	 */
+	d = irq_find_matching_host(bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
+	if (d)
+		return d;
+
+	return irq_find_host(bus->dev.of_node);
+#else
+	return NULL;
+#endif
+}