static void __init pcibios_reserve_legacy_regions()

in pci/pci-common.c [813:867]

• 50 lines of code
• 9 McCabe index (conditional complexity)

static void __init pcibios_reserve_legacy_regions(struct pci_bus *bus)
{
	struct pci_controller *hose = pci_bus_to_host(bus);
	resource_size_t	offset;
	struct resource *res, *pres;
	int i;

	pr_debug("Reserving legacy ranges for domain %04x\n",
							pci_domain_nr(bus));

	/* Check for IO */
	if (!(hose->io_resource.flags & IORESOURCE_IO))
		goto no_io;
	offset = (unsigned long)hose->io_base_virt - _IO_BASE;
	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
	BUG_ON(res == NULL);
	res->name = "Legacy IO";
	res->flags = IORESOURCE_IO;
	res->start = offset;
	res->end = (offset + 0xfff) & 0xfffffffful;
	pr_debug("Candidate legacy IO: %pR\n", res);
	if (request_resource(&hose->io_resource, res)) {
		pr_debug("PCI %04x:%02x Cannot reserve Legacy IO %pR\n",
		       pci_domain_nr(bus), bus->number, res);
		kfree(res);
	}

 no_io:
	/* Check for memory */
	offset = hose->pci_mem_offset;
	pr_debug("hose mem offset: %016llx\n", (unsigned long long)offset);
	for (i = 0; i < 3; i++) {
		pres = &hose->mem_resources[i];
		if (!(pres->flags & IORESOURCE_MEM))
			continue;
		pr_debug("hose mem res: %pR\n", pres);
		if ((pres->start - offset) <= 0xa0000 &&
		    (pres->end - offset) >= 0xbffff)
			break;
	}
	if (i >= 3)
		return;
	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
	BUG_ON(res == NULL);
	res->name = "Legacy VGA memory";
	res->flags = IORESOURCE_MEM;
	res->start = 0xa0000 + offset;
	res->end = 0xbffff + offset;
	pr_debug("Candidate VGA memory: %pR\n", res);
	if (request_resource(pres, res)) {
		pr_debug("PCI %04x:%02x Cannot reserve VGA memory %pR\n",
		       pci_domain_nr(bus), bus->number, res);
		kfree(res);
	}
}