diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
index 462594320d39..6fc3c7c554b2 100644
--- a/arch/x86/include/asm/pci.h
+++ b/arch/x86/include/asm/pci.h
@@ -20,6 +20,9 @@ struct pci_sysdata {
 #ifdef CONFIG_X86_64
 	void		*iommu;		/* IOMMU private data */
 #endif
+#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
+	void		*fwnode;	/* IRQ domain for MSI assignment */
+#endif
 };
 
 extern int pci_routeirq;
@@ -32,6 +35,7 @@ extern int noioapicreroute;
 static inline int pci_domain_nr(struct pci_bus *bus)
 {
 	struct pci_sysdata *sd = bus->sysdata;
+
 	return sd->domain;
 }
 
@@ -41,6 +45,17 @@ static inline int pci_proc_domain(struct pci_bus *bus)
 }
 #endif
 
+#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
+static inline void *_pci_root_bus_fwnode(struct pci_bus *bus)
+{
+	struct pci_sysdata *sd = bus->sysdata;
+
+	return sd->fwnode;
+}
+
+#define pci_root_bus_fwnode	_pci_root_bus_fwnode
+#endif
+
 /* Can be used to override the logic in pci_scan_bus for skipping
    already-configured bus numbers - to be used for buggy BIOSes
    or architectures with incomplete PCI setup by the loader */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 27df4a6585da..1bb44af6c9f0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1515,6 +1515,10 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
 
 #include <asm/pci.h>
 
+#ifndef pci_root_bus_fwnode
+#define pci_root_bus_fwnode(bus)	NULL
+#endif
+
 /* these helpers provide future and backwards compatibility
  * for accessing popular PCI BAR info */
 #define pci_resource_start(dev, bar)	((dev)->resource[(bar)].start)