PCI: Add generic domain handling

The handling of PCI domains (or PCI segments in ACPI speak) is usually a
straightforward affair but its implementation is currently left to the
architectural code, with pci_domain_nr(b) querying the value of the domain
associated with bus b.

This patch introduces CONFIG_PCI_DOMAINS_GENERIC as an option that can be
selected if an architecture wants a simple implementation where the value
of the domain associated with a bus is stored in struct pci_bus.

The architectures that select CONFIG_PCI_DOMAINS_GENERIC will then have to
implement pci_bus_assign_domain_nr() as a way of setting the domain number
associated with a root bus.  All child buses except the root bus will
inherit the domain_nr value from their parent.

Signed-off-by: Catalin Marinas <Catalin.Marinas@arm.com>
[Renamed pci_set_domain_nr() to pci_bus_assign_domain_nr()]
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arnd Bergmann <arnd@arndb.de>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e3cf8a2e6292..636d1c9156a9 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -485,7 +485,7 @@ void pci_read_bridge_bases(struct pci_bus *child)
         }
 }
 
-static struct pci_bus *pci_alloc_bus(void)
+static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
 {
         struct pci_bus *b;
 
@@ -500,6 +500,10 @@ static struct pci_bus *pci_alloc_bus(void)
         INIT_LIST_HEAD(&b->resources);
         b->max_bus_speed = PCI_SPEED_UNKNOWN;
         b->cur_bus_speed = PCI_SPEED_UNKNOWN;
+#ifdef CONFIG_PCI_DOMAINS_GENERIC
+        if (parent)
+                b->domain_nr = parent->domain_nr;
+#endif
         return b;
 }
 
@@ -671,7 +675,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
         /*
          * Allocate a new bus, and inherit stuff from the parent..
          */
-        child = pci_alloc_bus();
+        child = pci_alloc_bus(parent);
         if (!child)
                 return NULL;
 
@@ -1761,13 +1765,14 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
         char bus_addr[64];
         char *fmt;
 
-        b = pci_alloc_bus();
+        b = pci_alloc_bus(NULL);
         if (!b)
                 return NULL;
 
         b->sysdata = sysdata;
         b->ops = ops;
         b->number = b->busn_res.start = bus;
+        pci_bus_assign_domain_nr(b, parent);
         b2 = pci_find_bus(pci_domain_nr(b), bus);
         if (b2) {
                 /* If we already got to this bus through a different bridge, ignore it */