// SPDX-License-Identifier: GPL-2.0
/*
 * 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;
}

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

        return to_pci_host_bridge(root_bus->bridge);
}
EXPORT_SYMBOL_GPL(pci_find_host_bridge);

struct device *pci_get_host_bridge_device(struct pci_dev *dev)
{
        struct pci_bus *root_bus = find_pci_root_bus(dev->bus);
        struct device *bridge = root_bus->bridge;

        kobject_get(&bridge->kobj);
        return bridge;
}
EXPORT_SYMBOL_GPL(pci_get_host_bridge_device);

void  pci_put_host_bridge_device(struct device *dev)
{
        kobject_put(&dev->kobj);
}

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;
}
EXPORT_SYMBOL_GPL(pci_set_host_bridge_release);

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

        resource_list_for_each_entry(window, &bridge->windows) {
                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 = pci_find_host_bridge(bus);
        struct resource_entry *window;
        resource_size_t offset = 0;

        resource_list_for_each_entry(window, &bridge->windows) {
                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);