linux_kernel/drivers/pci/host-bridge.c

/*
 * host bridge related code
 */

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/module.h>

#include "pci.h"

static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
{
	while (bus->parent)
		bus = bus->parent;

	return bus;
}

static struct pci_host_bridge *find_pci_host_bridge(struct pci_bus *bus)
{
	struct pci_bus *root_bus = find_pci_root_bus(bus);

	return to_pci_host_bridge(root_bus->bridge);
}

void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
				 void (*release_fn)(struct pci_host_bridge *),
				 void *release_data)
{
	bridge->release_fn = release_fn;
	bridge->release_data = release_data;
}

void pcibios_resource_to_bus(struct pci_bus *bus, struct pci_bus_region *region,
			     struct resource *res)
{
	struct pci_host_bridge *bridge = find_pci_host_bridge(bus);
	struct pci_host_bridge_window *window;
	resource_size_t offset = 0;

	list_for_each_entry(window, &bridge->windows, list) {
		if (resource_contains(window->res, res)) {
			offset = window->offset;
			break;
		}
	}

	region->start = res->start - offset;
	region->end = res->end - offset;
}
EXPORT_SYMBOL(pcibios_resource_to_bus);

static bool region_contains(struct pci_bus_region *region1,
			    struct pci_bus_region *region2)
{
	return region1->start <= region2->start && region1->end >= region2->end;
}

void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
			     struct pci_bus_region *region)
{
	struct pci_host_bridge *bridge = find_pci_host_bridge(bus);
	struct pci_host_bridge_window *window;
	resource_size_t offset = 0;

	list_for_each_entry(window, &bridge->windows, list) {
		struct pci_bus_region bus_region;

		if (resource_type(res) != resource_type(window->res))
			continue;

		bus_region.start = window->res->start - window->offset;
		bus_region.end = window->res->end - window->offset;

		if (region_contains(&bus_region, region)) {
			offset = window->offset;
			break;
		}
	}

	res->start = region->start + offset;
	res->end = region->end + offset;
}
EXPORT_SYMBOL(pcibios_bus_to_resource);