PCI: Refactor pci_bus_assign_domain_nr() for CONFIG_PCI_DOMAINS_GENERIC

BugLink: https://bugs.launchpad.net/bugs/1797092

Instead of assigning bus->domain_nr inside pci_bus_assign_domain_nr(),
return the domain and let the caller do the assignment.  Rename
pci_bus_assign_domain_nr() to pci_bus_find_domain_nr() to reflect this.

No functional change intended.

[bhelgaas: changelog]
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
(cherry picked from commit 9c7cb891)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/pci/pci.c

@@ -4888,7 +4888,7 @@ int pci_get_new_domain_nr(void)
 }
 
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
-void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
+int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
 {
 	static int use_dt_domains = -1;
 	int domain = -1;
@@ -4932,7 +4932,7 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
 		domain = -1;
 	}
 
-	bus->domain_nr = domain;
+	return domain;
 }
 #endif
 #endif

drivers/pci/probe.c

@@ -2165,7 +2165,9 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	b->sysdata = sysdata;
 	b->ops = ops;
 	b->number = b->busn_res.start = bus;
-	pci_bus_assign_domain_nr(b, parent);
+#ifdef CONFIG_PCI_DOMAINS_GENERIC
+	b->domain_nr = pci_bus_find_domain_nr(b, parent);
+#endif
 	b2 = pci_find_bus(pci_domain_nr(b), bus);
 	if (b2) {
 		/* If we already got to this bus through a different bridge, ignore it */

include/linux/pci.h

@@ -1380,12 +1380,7 @@ static inline int pci_domain_nr(struct pci_bus *bus)
 {
 	return bus->domain_nr;
 }
-void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent);
-#else
-static inline void pci_bus_assign_domain_nr(struct pci_bus *bus,
-					struct device *parent)
-{
-}
+int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent);
 #endif
 
 /* some architectures require additional setup to direct VGA traffic */