/*
 *  pci_root.c - ACPI PCI Root Bridge Driver ($Revision: 40 $)
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
#include <linux/pci-aspm.h>
#include <linux/dmar.h>
#include <linux/acpi.h>
#include <linux/slab.h>
#include <linux/dmi.h>
#include <linux/platform_data/x86/apple.h>
#include <acpi/apei.h>  /* for acpi_hest_init() */

#include "internal.h"

#define _COMPONENT              ACPI_PCI_COMPONENT
ACPI_MODULE_NAME("pci_root");
#define ACPI_PCI_ROOT_CLASS             "pci_bridge"
#define ACPI_PCI_ROOT_DEVICE_NAME       "PCI Root Bridge"
static int acpi_pci_root_add(struct acpi_device *device,
                             const struct acpi_device_id *not_used);
static void acpi_pci_root_remove(struct acpi_device *device);

static int acpi_pci_root_scan_dependent(struct acpi_device *adev)
{
        acpiphp_check_host_bridge(adev);
        return 0;
}

#define ACPI_PCIE_REQ_SUPPORT (OSC_PCI_EXT_CONFIG_SUPPORT \
                                | OSC_PCI_ASPM_SUPPORT \
                                | OSC_PCI_CLOCK_PM_SUPPORT \
                                | OSC_PCI_MSI_SUPPORT)

static const struct acpi_device_id root_device_ids[] = {
        {"PNP0A03", 0},
        {"", 0},
};

static struct acpi_scan_handler pci_root_handler = {
        .ids = root_device_ids,
        .attach = acpi_pci_root_add,
        .detach = acpi_pci_root_remove,
        .hotplug = {
                .enabled = true,
                .scan_dependent = acpi_pci_root_scan_dependent,
        },
};

static DEFINE_MUTEX(osc_lock);

/**
 * acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
 * @handle - the ACPI CA node in question.
 *
 * Note: we could make this API take a struct acpi_device * instead, but
 * for now, it's more convenient to operate on an acpi_handle.
 */
int acpi_is_root_bridge(acpi_handle handle)
{
        int ret;
        struct acpi_device *device;

        ret = acpi_bus_get_device(handle, &device);
        if (ret)
                return 0;

        ret = acpi_match_device_ids(device, root_device_ids);
        if (ret)
                return 0;
        else
                return 1;
}
EXPORT_SYMBOL_GPL(acpi_is_root_bridge);

static acpi_status
get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
{
        struct resource *res = data;
        struct acpi_resource_address64 address;
        acpi_status status;

        status = acpi_resource_to_address64(resource, &address);
        if (ACPI_FAILURE(status))
                return AE_OK;

        if ((address.address.address_length > 0) &&
            (address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
                res->start = address.address.minimum;
                res->end = address.address.minimum + address.address.address_length - 1;
        }

        return AE_OK;
}

static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
                                             struct resource *res)
{
        acpi_status status;

        res->start = -1;
        status =
            acpi_walk_resources(handle, METHOD_NAME__CRS,
                                get_root_bridge_busnr_callback, res);
        if (ACPI_FAILURE(status))
                return status;
        if (res->start == -1)
                return AE_ERROR;
        return AE_OK;
}

struct pci_osc_bit_struct {
        u32 bit;
        char *desc;
};

static struct pci_osc_bit_struct pci_osc_support_bit[] = {
        { OSC_PCI_EXT_CONFIG_SUPPORT, "ExtendedConfig" },
        { OSC_PCI_ASPM_SUPPORT, "ASPM" },
        { OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
        { OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
        { OSC_PCI_MSI_SUPPORT, "MSI" },
};

static struct pci_osc_bit_struct pci_osc_control_bit[] = {
        { OSC_PCI_EXPRESS_NATIVE_HP_CONTROL, "PCIeHotplug" },
        { OSC_PCI_SHPC_NATIVE_HP_CONTROL, "SHPCHotplug" },
        { OSC_PCI_EXPRESS_PME_CONTROL, "PME" },
        { OSC_PCI_EXPRESS_AER_CONTROL, "AER" },
        { OSC_PCI_EXPRESS_CAPABILITY_CONTROL, "PCIeCapability" },
        { OSC_PCI_EXPRESS_LTR_CONTROL, "LTR" },
};

static void decode_osc_bits(struct acpi_pci_root *root, char *msg, u32 word,
                            struct pci_osc_bit_struct *table, int size)
{
        char buf[80];
        int i, len = 0;
        struct pci_osc_bit_struct *entry;

        buf[0] = '\0';
        for (i = 0, entry = table; i < size; i++, entry++)
                if (word & entry->bit)
                        len += snprintf(buf + len, sizeof(buf) - len, "%s%s",
                                        len ? " " : "", entry->desc);

        dev_info(&root->device->dev, "_OSC: %s [%s]\n", msg, buf);
}

static void decode_osc_support(struct acpi_pci_root *root, char *msg, u32 word)
{
        decode_osc_bits(root, msg, word, pci_osc_support_bit,
                        ARRAY_SIZE(pci_osc_support_bit));
}

static void decode_osc_control(struct acpi_pci_root *root, char *msg, u32 word)
{
        decode_osc_bits(root, msg, word, pci_osc_control_bit,
                        ARRAY_SIZE(pci_osc_control_bit));
}

static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766";

static acpi_status acpi_pci_run_osc(acpi_handle handle,
                                    const u32 *capbuf, u32 *retval)
{
        struct acpi_osc_context context = {
                .uuid_str = pci_osc_uuid_str,
                .rev = 1,
                .cap.length = 12,
                .cap.pointer = (void *)capbuf,
        };
        acpi_status status;

        status = acpi_run_osc(handle, &context);
        if (ACPI_SUCCESS(status)) {
                *retval = *((u32 *)(context.ret.pointer + 8));
                kfree(context.ret.pointer);
        }
        return status;
}

static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
                                        u32 support,
                                        u32 *control)
{
        acpi_status status;
        u32 result, capbuf[3];

        support &= OSC_PCI_SUPPORT_MASKS;
        support |= root->osc_support_set;

        capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
        capbuf[OSC_SUPPORT_DWORD] = support;
        if (control) {
                *control &= OSC_PCI_CONTROL_MASKS;
                capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set;
        } else {
                /* Run _OSC query only with existing controls. */
                capbuf[OSC_CONTROL_DWORD] = root->osc_control_set;
        }

        status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
        if (ACPI_SUCCESS(status)) {
                root->osc_support_set = support;
                if (control)
                        *control = result;
        }
        return status;
}

static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
{
        acpi_status status;

        mutex_lock(&osc_lock);
        status = acpi_pci_query_osc(root, flags, NULL);
        mutex_unlock(&osc_lock);
        return status;
}

struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
{
        struct acpi_pci_root *root;
        struct acpi_device *device;

        if (acpi_bus_get_device(handle, &device) ||
            acpi_match_device_ids(device, root_device_ids))
                return NULL;

        root = acpi_driver_data(device);

        return root;
}
EXPORT_SYMBOL_GPL(acpi_pci_find_root);

struct acpi_handle_node {
        struct list_head node;
        acpi_handle handle;
};

/**
 * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
 * @handle: the handle in question
 *
 * Given an ACPI CA handle, the desired PCI device is located in the
 * list of PCI devices.
 *
 * If the device is found, its reference count is increased and this
 * function returns a pointer to its data structure.  The caller must
 * decrement the reference count by calling pci_dev_put().
 * If no device is found, %NULL is returned.
 */
struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
{
        int dev, fn;
        unsigned long long adr;
        acpi_status status;
        acpi_handle phandle;
        struct pci_bus *pbus;
        struct pci_dev *pdev = NULL;
        struct acpi_handle_node *node, *tmp;
        struct acpi_pci_root *root;
        LIST_HEAD(device_list);

        /*
         * Walk up the ACPI CA namespace until we reach a PCI root bridge.
         */
        phandle = handle;
        while (!acpi_is_root_bridge(phandle)) {
                node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
                if (!node)
                        goto out;

                INIT_LIST_HEAD(&node->node);
                node->handle = phandle;
                list_add(&node->node, &device_list);

                status = acpi_get_parent(phandle, &phandle);
                if (ACPI_FAILURE(status))
                        goto out;
        }

        root = acpi_pci_find_root(phandle);
        if (!root)
                goto out;

        pbus = root->bus;

        /*
         * Now, walk back down the PCI device tree until we return to our
         * original handle. Assumes that everything between the PCI root
         * bridge and the device we're looking for must be a P2P bridge.
         */
        list_for_each_entry(node, &device_list, node) {
                acpi_handle hnd = node->handle;
                status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
                if (ACPI_FAILURE(status))
                        goto out;
                dev = (adr >> 16) & 0xffff;
                fn  = adr & 0xffff;

                pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
                if (!pdev || hnd == handle)
                        break;

                pbus = pdev->subordinate;
                pci_dev_put(pdev);

                /*
                 * This function may be called for a non-PCI device that has a
                 * PCI parent (eg. a disk under a PCI SATA controller).  In that
                 * case pdev->subordinate will be NULL for the parent.
                 */
                if (!pbus) {
                        dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
                        pdev = NULL;
                        break;
                }
        }
out:
        list_for_each_entry_safe(node, tmp, &device_list, node)
                kfree(node);

        return pdev;
}
EXPORT_SYMBOL_GPL(acpi_get_pci_dev);

/**
 * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
 * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
 * @mask: Mask of _OSC bits to request control of, place to store control mask.
 * @req: Mask of _OSC bits the control of is essential to the caller.
 *
 * Run _OSC query for @mask and if that is successful, compare the returned
 * mask of control bits with @req.  If all of the @req bits are set in the
 * returned mask, run _OSC request for it.
 *
 * The variable at the @mask address may be modified regardless of whether or
 * not the function returns success.  On success it will contain the mask of
 * _OSC bits the BIOS has granted control of, but its contents are meaningless
 * on failure.
 **/
acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
{
        struct acpi_pci_root *root;
        acpi_status status = AE_OK;
        u32 ctrl, capbuf[3];

        if (!mask)
                return AE_BAD_PARAMETER;

        ctrl = *mask & OSC_PCI_CONTROL_MASKS;
        if ((ctrl & req) != req)
                return AE_TYPE;

        root = acpi_pci_find_root(handle);
        if (!root)
                return AE_NOT_EXIST;

        mutex_lock(&osc_lock);

        *mask = ctrl | root->osc_control_set;
        /* No need to evaluate _OSC if the control was already granted. */
        if ((root->osc_control_set & ctrl) == ctrl)
                goto out;

        /* Need to check the available controls bits before requesting them. */
        while (*mask) {
                status = acpi_pci_query_osc(root, root->osc_support_set, mask);
                if (ACPI_FAILURE(status))
                        goto out;
                if (ctrl == *mask)
                        break;
                decode_osc_control(root, "platform does not support",
                                   ctrl & ~(*mask));
                ctrl = *mask;
        }

        if ((ctrl & req) != req) {
                decode_osc_control(root, "not requesting control; platform does not support",
                                   req & ~(ctrl));
                status = AE_SUPPORT;
                goto out;
        }

        capbuf[OSC_QUERY_DWORD] = 0;
        capbuf[OSC_SUPPORT_DWORD] = root->osc_support_set;
        capbuf[OSC_CONTROL_DWORD] = ctrl;
        status = acpi_pci_run_osc(handle, capbuf, mask);
        if (ACPI_SUCCESS(status))
                root->osc_control_set = *mask;
out:
        mutex_unlock(&osc_lock);
        return status;
}
EXPORT_SYMBOL(acpi_pci_osc_control_set);

static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
{
        u32 support, control, requested;
        acpi_status status;
        struct acpi_device *device = root->device;
        acpi_handle handle = device->handle;

        /*
         * Apple always return failure on _OSC calls when _OSI("Darwin") has
         * been called successfully. We know the feature set supported by the
         * platform, so avoid calling _OSC at all
         */
        if (x86_apple_machine) {
                root->osc_control_set = ~OSC_PCI_EXPRESS_PME_CONTROL;
                decode_osc_control(root, "OS assumes control of",
                                   root->osc_control_set);
                return;
        }

        /*
         * All supported architectures that use ACPI have support for
         * PCI domains, so we indicate this in _OSC support capabilities.
         */
        support = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
        if (pci_ext_cfg_avail())
                support |= OSC_PCI_EXT_CONFIG_SUPPORT;
        if (pcie_aspm_support_enabled())
                support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
        if (pci_msi_enabled())
                support |= OSC_PCI_MSI_SUPPORT;

        decode_osc_support(root, "OS supports", support);
        status = acpi_pci_osc_support(root, support);
        if (ACPI_FAILURE(status)) {
                dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
                         acpi_format_exception(status));
                *no_aspm = 1;
                return;
        }

        if (pcie_ports_disabled) {
                dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
                return;
        }

        if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
                decode_osc_support(root, "not requesting OS control; OS requires",
                                   ACPI_PCIE_REQ_SUPPORT);
                return;
        }

        control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
                | OSC_PCI_EXPRESS_PME_CONTROL;

        if (IS_ENABLED(CONFIG_PCIEASPM))
                control |= OSC_PCI_EXPRESS_LTR_CONTROL;

        if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
                control |= OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;

        if (IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
                control |= OSC_PCI_SHPC_NATIVE_HP_CONTROL;

        if (pci_aer_available()) {
                if (aer_acpi_firmware_first())
                        dev_info(&device->dev,
                                 "PCIe AER handled by firmware\n");
                else
                        control |= OSC_PCI_EXPRESS_AER_CONTROL;
        }

        requested = control;
        status = acpi_pci_osc_control_set(handle, &control,
                                          OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
        if (ACPI_SUCCESS(status)) {
                decode_osc_control(root, "OS now controls", control);
                if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
                        /*
                         * We have ASPM control, but the FADT indicates that
                         * it's unsupported. Leave existing configuration
                         * intact and prevent the OS from touching it.
                         */
                        dev_info(&device->dev, "FADT indicates ASPM is unsupported, using BIOS configuration\n");
                        *no_aspm = 1;
                }
        } else {
                decode_osc_control(root, "OS requested", requested);
                decode_osc_control(root, "platform willing to grant", control);
                dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
                        acpi_format_exception(status));

                /*
                 * We want to disable ASPM here, but aspm_disabled
                 * needs to remain in its state from boot so that we
                 * properly handle PCIe 1.1 devices.  So we set this
                 * flag here, to defer the action until after the ACPI
                 * root scan.
                 */
                *no_aspm = 1;
        }
}

static int acpi_pci_root_add(struct acpi_device *device,
                             const struct acpi_device_id *not_used)
{
        unsigned long long segment, bus;
        acpi_status status;
        int result;
        struct acpi_pci_root *root;
        acpi_handle handle = device->handle;
        int no_aspm = 0;
        bool hotadd = system_state == SYSTEM_RUNNING;

        root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
        if (!root)
                return -ENOMEM;

        segment = 0;
        status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
                                       &segment);
        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
                dev_err(&device->dev,  "can't evaluate _SEG\n");
                result = -ENODEV;
                goto end;
        }

        /* Check _CRS first, then _BBN.  If no _BBN, default to zero. */
        root->secondary.flags = IORESOURCE_BUS;
        status = try_get_root_bridge_busnr(handle, &root->secondary);
        if (ACPI_FAILURE(status)) {
                /*
                 * We need both the start and end of the downstream bus range
                 * to interpret _CBA (MMCONFIG base address), so it really is
                 * supposed to be in _CRS.  If we don't find it there, all we
                 * can do is assume [_BBN-0xFF] or [0-0xFF].
                 */
                root->secondary.end = 0xFF;
                dev_warn(&device->dev,
                         FW_BUG "no secondary bus range in _CRS\n");
                status = acpi_evaluate_integer(handle, METHOD_NAME__BBN,
                                               NULL, &bus);
                if (ACPI_SUCCESS(status))
                        root->secondary.start = bus;
                else if (status == AE_NOT_FOUND)
                        root->secondary.start = 0;
                else {
                        dev_err(&device->dev, "can't evaluate _BBN\n");
                        result = -ENODEV;
                        goto end;
                }
        }

        root->device = device;
        root->segment = segment & 0xFFFF;
        strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
        strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
        device->driver_data = root;

        if (hotadd && dmar_device_add(handle)) {
                result = -ENXIO;
                goto end;
        }

        pr_info(PREFIX "%s [%s] (domain %04x %pR)\n",
               acpi_device_name(device), acpi_device_bid(device),
               root->segment, &root->secondary);

        root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);

        negotiate_os_control(root, &no_aspm);

        /*
         * TBD: Need PCI interface for enumeration/configuration of roots.
         */

        /*
         * Scan the Root Bridge
         * --------------------
         * Must do this prior to any attempt to bind the root device, as the
         * PCI namespace does not get created until this call is made (and
         * thus the root bridge's pci_dev does not exist).
         */
        root->bus = pci_acpi_scan_root(root);
        if (!root->bus) {
                dev_err(&device->dev,
                        "Bus %04x:%02x not present in PCI namespace\n",
                        root->segment, (unsigned int)root->secondary.start);
                device->driver_data = NULL;
                result = -ENODEV;
                goto remove_dmar;
        }

        if (no_aspm)
                pcie_no_aspm();

        pci_acpi_add_bus_pm_notifier(device);
        device_set_wakeup_capable(root->bus->bridge, device->wakeup.flags.valid);

        if (hotadd) {
                pcibios_resource_survey_bus(root->bus);
                pci_assign_unassigned_root_bus_resources(root->bus);
                /*
                 * This is only called for the hotadd case. For the boot-time
                 * case, we need to wait until after PCI initialization in
                 * order to deal with IOAPICs mapped in on a PCI BAR.
                 *
                 * This is currently x86-specific, because acpi_ioapic_add()
                 * is an empty function without CONFIG_ACPI_HOTPLUG_IOAPIC.
                 * And CONFIG_ACPI_HOTPLUG_IOAPIC depends on CONFIG_X86_IO_APIC
                 * (see drivers/acpi/Kconfig).
                 */
                acpi_ioapic_add(root->device->handle);
        }

        pci_lock_rescan_remove();
        pci_bus_add_devices(root->bus);
        pci_unlock_rescan_remove();
        return 1;

remove_dmar:
        if (hotadd)
                dmar_device_remove(handle);
end:
        kfree(root);
        return result;
}

static void acpi_pci_root_remove(struct acpi_device *device)
{
        struct acpi_pci_root *root = acpi_driver_data(device);

        pci_lock_rescan_remove();

        pci_stop_root_bus(root->bus);

        pci_ioapic_remove(root);
        device_set_wakeup_capable(root->bus->bridge, false);
        pci_acpi_remove_bus_pm_notifier(device);

        pci_remove_root_bus(root->bus);
        WARN_ON(acpi_ioapic_remove(root));

        dmar_device_remove(device->handle);

        pci_unlock_rescan_remove();

        kfree(root);
}

/*
 * Following code to support acpi_pci_root_create() is copied from
 * arch/x86/pci/acpi.c and modified so it could be reused by x86, IA64
 * and ARM64.
 */
static void acpi_pci_root_validate_resources(struct device *dev,
                                             struct list_head *resources,
                                             unsigned long type)
{
        LIST_HEAD(list);
        struct resource *res1, *res2, *root = NULL;
        struct resource_entry *tmp, *entry, *entry2;

        BUG_ON((type & (IORESOURCE_MEM | IORESOURCE_IO)) == 0);
        root = (type & IORESOURCE_MEM) ? &iomem_resource : &ioport_resource;

        list_splice_init(resources, &list);
        resource_list_for_each_entry_safe(entry, tmp, &list) {
                bool free = false;
                resource_size_t end;

                res1 = entry->res;
                if (!(res1->flags & type))
                        goto next;

                /* Exclude non-addressable range or non-addressable portion */
                end = min(res1->end, root->end);
                if (end <= res1->start) {
                        dev_info(dev, "host bridge window %pR (ignored, not CPU addressable)\n",
                                 res1);
                        free = true;
                        goto next;
                } else if (res1->end != end) {
                        dev_info(dev, "host bridge window %pR ([%#llx-%#llx] ignored, not CPU addressable)\n",
                                 res1, (unsigned long long)end + 1,
                                 (unsigned long long)res1->end);
                        res1->end = end;
                }

                resource_list_for_each_entry(entry2, resources) {
                        res2 = entry2->res;
                        if (!(res2->flags & type))
                                continue;

                        /*
                         * I don't like throwing away windows because then
                         * our resources no longer match the ACPI _CRS, but
                         * the kernel resource tree doesn't allow overlaps.
                         */
                        if (resource_overlaps(res1, res2)) {
                                res2->start = min(res1->start, res2->start);
                                res2->end = max(res1->end, res2->end);
                                dev_info(dev, "host bridge window expanded to %pR; %pR ignored\n",
                                         res2, res1);
                                free = true;
                                goto next;
                        }
                }

next:
                resource_list_del(entry);
                if (free)
                        resource_list_free_entry(entry);
                else
                        resource_list_add_tail(entry, resources);
        }
}

static void acpi_pci_root_remap_iospace(struct fwnode_handle *fwnode,
                        struct resource_entry *entry)
{
#ifdef PCI_IOBASE
        struct resource *res = entry->res;
        resource_size_t cpu_addr = res->start;
        resource_size_t pci_addr = cpu_addr - entry->offset;
        resource_size_t length = resource_size(res);
        unsigned long port;

        if (pci_register_io_range(fwnode, cpu_addr, length))
                goto err;

        port = pci_address_to_pio(cpu_addr);
        if (port == (unsigned long)-1)
                goto err;

        res->start = port;
        res->end = port + length - 1;
        entry->offset = port - pci_addr;

        if (pci_remap_iospace(res, cpu_addr) < 0)
                goto err;

        pr_info("Remapped I/O %pa to %pR\n", &cpu_addr, res);
        return;
err:
        res->flags |= IORESOURCE_DISABLED;
#endif
}

int acpi_pci_probe_root_resources(struct acpi_pci_root_info *info)
{
        int ret;
        struct list_head *list = &info->resources;
        struct acpi_device *device = info->bridge;
        struct resource_entry *entry, *tmp;
        unsigned long flags;

        flags = IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_MEM_8AND16BIT;
        ret = acpi_dev_get_resources(device, list,
                                     acpi_dev_filter_resource_type_cb,
                                     (void *)flags);
        if (ret < 0)
                dev_warn(&device->dev,
                         "failed to parse _CRS method, error code %d\n", ret);
        else if (ret == 0)
                dev_dbg(&device->dev,
                        "no IO and memory resources present in _CRS\n");
        else {
                resource_list_for_each_entry_safe(entry, tmp, list) {
                        if (entry->res->flags & IORESOURCE_IO)
                                acpi_pci_root_remap_iospace(&device->fwnode,
                                                entry);

                        if (entry->res->flags & IORESOURCE_DISABLED)
                                resource_list_destroy_entry(entry);
                        else
                                entry->res->name = info->name;
                }
                acpi_pci_root_validate_resources(&device->dev, list,
                                                 IORESOURCE_MEM);
                acpi_pci_root_validate_resources(&device->dev, list,
                                                 IORESOURCE_IO);
        }

        return ret;
}

static void pci_acpi_root_add_resources(struct acpi_pci_root_info *info)
{
        struct resource_entry *entry, *tmp;
        struct resource *res, *conflict, *root = NULL;

        resource_list_for_each_entry_safe(entry, tmp, &info->resources) {
                res = entry->res;
                if (res->flags & IORESOURCE_MEM)
                        root = &iomem_resource;
                else if (res->flags & IORESOURCE_IO)
                        root = &ioport_resource;
                else
                        continue;

                /*
                 * Some legacy x86 host bridge drivers use iomem_resource and
                 * ioport_resource as default resource pool, skip it.
                 */
                if (res == root)
                        continue;

                conflict = insert_resource_conflict(root, res);
                if (conflict) {
                        dev_info(&info->bridge->dev,
                                 "ignoring host bridge window %pR (conflicts with %s %pR)\n",
                                 res, conflict->name, conflict);
                        resource_list_destroy_entry(entry);
                }
        }
}

static void __acpi_pci_root_release_info(struct acpi_pci_root_info *info)
{
        struct resource *res;
        struct resource_entry *entry, *tmp;

        if (!info)
                return;

        resource_list_for_each_entry_safe(entry, tmp, &info->resources) {
                res = entry->res;
                if (res->parent &&
                    (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
                        release_resource(res);
                resource_list_destroy_entry(entry);
        }

        info->ops->release_info(info);
}

static void acpi_pci_root_release_info(struct pci_host_bridge *bridge)
{
        struct resource *res;
        struct resource_entry *entry;

        resource_list_for_each_entry(entry, &bridge->windows) {
                res = entry->res;
                if (res->flags & IORESOURCE_IO)
                        pci_unmap_iospace(res);
                if (res->parent &&
                    (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
                        release_resource(res);
        }
        __acpi_pci_root_release_info(bridge->release_data);
}

struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
                                     struct acpi_pci_root_ops *ops,
                                     struct acpi_pci_root_info *info,
                                     void *sysdata)
{
        int ret, busnum = root->secondary.start;
        struct acpi_device *device = root->device;
        int node = acpi_get_node(device->handle);
        struct pci_bus *bus;
        struct pci_host_bridge *host_bridge;

        info->root = root;
        info->bridge = device;
        info->ops = ops;
        INIT_LIST_HEAD(&info->resources);
        snprintf(info->name, sizeof(info->name), "PCI Bus %04x:%02x",
                 root->segment, busnum);

        if (ops->init_info && ops->init_info(info))
                goto out_release_info;
        if (ops->prepare_resources)
                ret = ops->prepare_resources(info);
        else
                ret = acpi_pci_probe_root_resources(info);
        if (ret < 0)
                goto out_release_info;

        pci_acpi_root_add_resources(info);
        pci_add_resource(&info->resources, &root->secondary);
        bus = pci_create_root_bus(NULL, busnum, ops->pci_ops,
                                  sysdata, &info->resources);
        if (!bus)
                goto out_release_info;

        host_bridge = to_pci_host_bridge(bus->bridge);
        if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
                host_bridge->native_pcie_hotplug = 0;
        if (!(root->osc_control_set & OSC_PCI_SHPC_NATIVE_HP_CONTROL))
                host_bridge->native_shpc_hotplug = 0;
        if (!(root->osc_control_set & OSC_PCI_EXPRESS_AER_CONTROL))
                host_bridge->native_aer = 0;
        if (!(root->osc_control_set & OSC_PCI_EXPRESS_PME_CONTROL))
                host_bridge->native_pme = 0;
        if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
                host_bridge->native_ltr = 0;

        pci_scan_child_bus(bus);
        pci_set_host_bridge_release(host_bridge, acpi_pci_root_release_info,
                                    info);
        if (node != NUMA_NO_NODE)
                dev_printk(KERN_DEBUG, &bus->dev, "on NUMA node %d\n", node);
        return bus;

out_release_info:
        __acpi_pci_root_release_info(info);
        return NULL;
}

void __init acpi_pci_root_init(void)
{
        acpi_hest_init();
        if (acpi_pci_disabled)
                return;

        pci_acpi_crs_quirks();
        acpi_scan_add_handler_with_hotplug(&pci_root_handler, "pci_root");
}