ARM64: PCI: Add acpi_pci_bus_find_domain_nr()

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

Extend pci_bus_find_domain_nr() so it can find the domain from either:

  - ACPI, via the new acpi_pci_bus_find_domain_nr() interface, or
  - DT, via of_pci_bus_find_domain_nr()

Note that this is only used for CONFIG_PCI_DOMAINS_GENERIC=y, so it does
not affect x86 or ia64.

[bhelgaas: changelog]
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
(cherry picked from commit 2ab51dde)
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>

arch/arm64/kernel/pci.c

@@ -17,6 +17,7 @@
 #include <linux/mm.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
+#include <linux/pci.h>
 #include <linux/slab.h>
 
 #include <asm/pci-bridge.h>
@@ -87,6 +88,12 @@ EXPORT_SYMBOL(pcibus_to_node);
 #endif
 
 #ifdef CONFIG_ACPI
+
+int acpi_pci_bus_find_domain_nr(struct pci_bus *bus)
+{
+	return 0;
+}
+
 /* Root bridge scanning */
 struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 {

drivers/pci/pci.c

@@ -7,6 +7,7 @@
  *	Copyright 1997 -- 2000 Martin Mares <mj@ucw.cz>
  */
 
+#include <linux/acpi.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/init.h>
@@ -4937,7 +4938,8 @@ static int of_pci_bus_find_domain_nr(struct device *parent)
 
 int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
 {
-	return of_pci_bus_find_domain_nr(parent);
+	return acpi_disabled ? of_pci_bus_find_domain_nr(parent) :
+			       acpi_pci_bus_find_domain_nr(bus);
 }
 #endif
 #endif

include/linux/pci.h

@@ -1380,6 +1380,12 @@ static inline int pci_domain_nr(struct pci_bus *bus)
 {
 	return bus->domain_nr;
 }
+#ifdef CONFIG_ACPI
+int acpi_pci_bus_find_domain_nr(struct pci_bus *bus);
+#else
+static inline int acpi_pci_bus_find_domain_nr(struct pci_bus *bus)
+{ return 0; }
+#endif
 int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent);
 #endif