static int pci_register_host_bridge()

in probe.c [883:1035]

• 118 lines of code
• 24 McCabe index (conditional complexity)

static int pci_register_host_bridge(struct pci_host_bridge *bridge)
{
	struct device *parent = bridge->dev.parent;
	struct resource_entry *window, *next, *n;
	struct pci_bus *bus, *b;
	resource_size_t offset, next_offset;
	LIST_HEAD(resources);
	struct resource *res, *next_res;
	char addr[64], *fmt;
	const char *name;
	int err;

	bus = pci_alloc_bus(NULL);
	if (!bus)
		return -ENOMEM;

	bridge->bus = bus;

	bus->sysdata = bridge->sysdata;
	bus->ops = bridge->ops;
	bus->number = bus->busn_res.start = bridge->busnr;
#ifdef CONFIG_PCI_DOMAINS_GENERIC
	if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
		bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
	else
		bus->domain_nr = bridge->domain_nr;
#endif

	b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);
	if (b) {
		/* Ignore it if we already got here via a different bridge */
		dev_dbg(&b->dev, "bus already known\n");
		err = -EEXIST;
		goto free;
	}

	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(bus),
		     bridge->busnr);

	err = pcibios_root_bridge_prepare(bridge);
	if (err)
		goto free;

	/* Temporarily move resources off the list */
	list_splice_init(&bridge->windows, &resources);
	err = device_add(&bridge->dev);
	if (err) {
		put_device(&bridge->dev);
		goto free;
	}
	bus->bridge = get_device(&bridge->dev);
	device_enable_async_suspend(bus->bridge);
	pci_set_bus_of_node(bus);
	pci_set_bus_msi_domain(bus);
	if (bridge->msi_domain && !dev_get_msi_domain(&bus->dev) &&
	    !pci_host_of_has_msi_map(parent))
		bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;

	if (!parent)
		set_dev_node(bus->bridge, pcibus_to_node(bus));

	bus->dev.class = &pcibus_class;
	bus->dev.parent = bus->bridge;

	dev_set_name(&bus->dev, "%04x:%02x", pci_domain_nr(bus), bus->number);
	name = dev_name(&bus->dev);

	err = device_register(&bus->dev);
	if (err)
		goto unregister;

	pcibios_add_bus(bus);

	if (bus->ops->add_bus) {
		err = bus->ops->add_bus(bus);
		if (WARN_ON(err < 0))
			dev_err(&bus->dev, "failed to add bus: %d\n", err);
	}

	/* Create legacy_io and legacy_mem files for this bus */
	pci_create_legacy_files(bus);

	if (parent)
		dev_info(parent, "PCI host bridge to bus %s\n", name);
	else
		pr_info("PCI host bridge to bus %s\n", name);

	if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
		dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");

	/* Coalesce contiguous windows */
	resource_list_for_each_entry_safe(window, n, &resources) {
		if (list_is_last(&window->node, &resources))
			break;

		next = list_next_entry(window, node);
		offset = window->offset;
		res = window->res;
		next_offset = next->offset;
		next_res = next->res;

		if (res->flags != next_res->flags || offset != next_offset)
			continue;

		if (res->end + 1 == next_res->start) {
			next_res->start = res->start;
			res->flags = res->start = res->end = 0;
		}
	}

	/* Add initial resources to the bus */
	resource_list_for_each_entry_safe(window, n, &resources) {
		offset = window->offset;
		res = window->res;
		if (!res->end)
			continue;

		list_move_tail(&window->node, &bridge->windows);

		if (res->flags & IORESOURCE_BUS)
			pci_bus_insert_busn_res(bus, bus->number, res->end);
		else
			pci_bus_add_resource(bus, res, 0);

		if (offset) {
			if (resource_type(res) == IORESOURCE_IO)
				fmt = " (bus address [%#06llx-%#06llx])";
			else
				fmt = " (bus address [%#010llx-%#010llx])";

			snprintf(addr, sizeof(addr), fmt,
				 (unsigned long long)(res->start - offset),
				 (unsigned long long)(res->end - offset));
		} else
			addr[0] = '\0';

		dev_info(&bus->dev, "root bus resource %pR%s\n", res, addr);
	}

	down_write(&pci_bus_sem);
	list_add_tail(&bus->node, &pci_root_buses);
	up_write(&pci_bus_sem);

	return 0;

unregister:
	put_device(&bridge->dev);
	device_del(&bridge->dev);

free:
	kfree(bus);
	return err;
}