// SPDX-License-Identifier: GPL-2.0
/*
 * Support routines for initializing a PCI subsystem
 *
 * Extruded from code written by
 *      Dave Rusling (david.rusling@reo.mts.dec.com)
 *      David Mosberger (davidm@cs.arizona.edu)
 *      David Miller (davem@redhat.com)
 *
 * Nov 2000, Ivan Kokshaysky <ink@jurassic.park.msu.ru>
 *           PCI-PCI bridges cleanup, sorted resource allocation.
 * Feb 2002, Ivan Kokshaysky <ink@jurassic.park.msu.ru>
 *           Converted to allocation in 3 passes, which gives
 *           tighter packing. Prefetchable range support.
 */

#include <linux/align.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/cache.h>
#include <linux/limits.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include "pci.h"

#define PCI_RES_TYPE_MASK \
        (IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_PREFETCH |\
         IORESOURCE_MEM_64)

unsigned int pci_flags;
EXPORT_SYMBOL_GPL(pci_flags);

struct pci_dev_resource {
        struct list_head list;
        struct resource *res;
        struct pci_dev *dev;
        resource_size_t start;
        resource_size_t end;
        resource_size_t add_size;
        resource_size_t min_align;
        unsigned long flags;
};

static void pci_dev_res_free_list(struct list_head *head)
{
        struct pci_dev_resource *dev_res, *tmp;

        list_for_each_entry_safe(dev_res, tmp, head, list) {
                list_del(&dev_res->list);
                kfree(dev_res);
        }
}

/**
 * pci_dev_res_add_to_list() - Add a new resource tracker to the list
 * @head:       Head of the list
 * @dev:        Device to which the resource belongs
 * @res:        Resource to be tracked
 * @add_size:   Additional size to be optionally added to the resource
 * @min_align:  Minimum memory window alignment
 */
int pci_dev_res_add_to_list(struct list_head *head, struct pci_dev *dev,
                            struct resource *res, resource_size_t add_size,
                            resource_size_t min_align)
{
        struct pci_dev_resource *tmp;

        tmp = kzalloc_obj(*tmp);
        if (!tmp)
                return -ENOMEM;

        tmp->res = res;
        tmp->dev = dev;
        tmp->start = res->start;
        tmp->end = res->end;
        tmp->flags = res->flags;
        tmp->add_size = add_size;
        tmp->min_align = min_align;

        list_add(&tmp->list, head);

        return 0;
}

static void pci_dev_res_remove_from_list(struct list_head *head,
                                         struct resource *res)
{
        struct pci_dev_resource *dev_res, *tmp;

        list_for_each_entry_safe(dev_res, tmp, head, list) {
                if (dev_res->res == res) {
                        list_del(&dev_res->list);
                        kfree(dev_res);
                        break;
                }
        }
}

static struct pci_dev_resource *res_to_dev_res(struct list_head *head,
                                               struct resource *res)
{
        struct pci_dev_resource *dev_res;

        list_for_each_entry(dev_res, head, list) {
                if (dev_res->res == res)
                        return dev_res;
        }

        return NULL;
}

static resource_size_t get_res_add_size(struct list_head *head,
                                        struct resource *res)
{
        struct pci_dev_resource *dev_res;

        dev_res = res_to_dev_res(head, res);
        return dev_res ? dev_res->add_size : 0;
}

static void pci_dev_res_restore(struct pci_dev_resource *dev_res)
{
        struct resource *res = dev_res->res;
        struct pci_dev *dev = dev_res->dev;
        int idx = pci_resource_num(dev, res);
        const char *res_name = pci_resource_name(dev, idx);

        if (WARN_ON_ONCE(resource_assigned(res)))
                return;

        res->start = dev_res->start;
        res->end = dev_res->end;
        res->flags = dev_res->flags;

        pci_dbg(dev, "%s %pR: resource restored\n", res_name, res);
}

/*
 * Helper function for sizing routines.  Assigned resources have non-NULL
 * parent resource.
 *
 * Return first unassigned resource of the correct type.  If there is none,
 * return first assigned resource of the correct type.  If none of the
 * above, return NULL.
 *
 * Returning an assigned resource of the correct type allows the caller to
 * distinguish between already assigned and no resource of the correct type.
 */
static struct resource *find_bus_resource_of_type(struct pci_bus *bus,
                                                  unsigned long type_mask,
                                                  unsigned long type)
{
        struct resource *r, *r_assigned = NULL;

        pci_bus_for_each_resource(bus, r) {
                if (!r || r == &ioport_resource || r == &iomem_resource)
                        continue;

                if ((r->flags & type_mask) != type)
                        continue;

                if (!resource_assigned(r))
                        return r;
                if (!r_assigned)
                        r_assigned = r;
        }
        return r_assigned;
}

/**
 * pbus_select_window_for_type - Select bridge window for a resource type
 * @bus: PCI bus
 * @type: Resource type (resource flags can be passed as is)
 *
 * Select the bridge window based on a resource @type.
 *
 * For memory resources, the selection is done as follows:
 *
 * Any non-prefetchable resource is put into the non-prefetchable window.
 *
 * If there is no prefetchable MMIO window, put all memory resources into the
 * non-prefetchable window.
 *
 * If there's a 64-bit prefetchable MMIO window, put all 64-bit prefetchable
 * resources into it and place 32-bit prefetchable memory into the
 * non-prefetchable window.
 *
 * Otherwise, put all prefetchable resources into the prefetchable window.
 *
 * Return: the bridge window resource or NULL if no bridge window is found.
 */
static struct resource *pbus_select_window_for_type(struct pci_bus *bus,
                                                    unsigned long type)
{
        int iores_type = type & IORESOURCE_TYPE_BITS;   /* w/o 64bit & pref */
        struct resource *mmio, *mmio_pref, *win;

        type &= PCI_RES_TYPE_MASK;                      /* with 64bit & pref */

        if ((iores_type != IORESOURCE_IO) && (iores_type != IORESOURCE_MEM))
                return NULL;

        if (pci_is_root_bus(bus)) {
                win = find_bus_resource_of_type(bus, type, type);
                if (win)
                        return win;

                type &= ~IORESOURCE_MEM_64;
                win = find_bus_resource_of_type(bus, type, type);
                if (win)
                        return win;

                type &= ~IORESOURCE_PREFETCH;
                return find_bus_resource_of_type(bus, type, type);
        }

        switch (iores_type) {
        case IORESOURCE_IO:
                win = pci_bus_resource_n(bus, PCI_BUS_BRIDGE_IO_WINDOW);
                if (win && (win->flags & IORESOURCE_IO))
                        return win;
                return NULL;

        case IORESOURCE_MEM:
                mmio = pci_bus_resource_n(bus, PCI_BUS_BRIDGE_MEM_WINDOW);
                mmio_pref = pci_bus_resource_n(bus, PCI_BUS_BRIDGE_PREF_MEM_WINDOW);

                if (mmio && !(mmio->flags & IORESOURCE_MEM))
                        mmio = NULL;
                if (mmio_pref && !(mmio_pref->flags & IORESOURCE_MEM))
                        mmio_pref = NULL;

                if (!(type & IORESOURCE_PREFETCH) || !mmio_pref)
                        return mmio;

                if ((type & IORESOURCE_MEM_64) ||
                    !(mmio_pref->flags & IORESOURCE_MEM_64))
                        return mmio_pref;

                return mmio;
        default:
                return NULL;
        }
}

/**
 * pbus_select_window - Select bridge window for a resource
 * @bus: PCI bus
 * @res: Resource
 *
 * Select the bridge window for @res. If the resource is already assigned,
 * return the current bridge window.
 *
 * For memory resources, the selection is done as follows:
 *
 * Any non-prefetchable resource is put into the non-prefetchable window.
 *
 * If there is no prefetchable MMIO window, put all memory resources into the
 * non-prefetchable window.
 *
 * If there's a 64-bit prefetchable MMIO window, put all 64-bit prefetchable
 * resources into it and place 32-bit prefetchable memory into the
 * non-prefetchable window.
 *
 * Otherwise, put all prefetchable resources into the prefetchable window.
 *
 * Return: the bridge window resource or NULL if no bridge window is found.
 */
struct resource *pbus_select_window(struct pci_bus *bus,
                                    const struct resource *res)
{
        if (resource_assigned(res))
                return res->parent;

        return pbus_select_window_for_type(bus, res->flags);
}

static bool pdev_resources_assignable(struct pci_dev *dev)
{
        u16 class = dev->class >> 8, command;

        /* Don't touch classless devices or host bridges or IOAPICs */
        if (class == PCI_CLASS_NOT_DEFINED || class == PCI_CLASS_BRIDGE_HOST)
                return false;

        /* Don't touch IOAPIC devices already enabled by firmware */
        if (class == PCI_CLASS_SYSTEM_PIC) {
                pci_read_config_word(dev, PCI_COMMAND, &command);
                if (command & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
                        return false;
        }

        return true;
}

static bool pdev_resource_assignable(struct pci_dev *dev, struct resource *res)
{
        int idx = pci_resource_num(dev, res);

        if (!res->flags)
                return false;

        if (pci_resource_is_bridge_win(idx) && res->flags & IORESOURCE_DISABLED)
                return false;

        return true;
}

static bool pdev_resource_should_fit(struct pci_dev *dev, struct resource *res)
{
        if (resource_assigned(res))
                return false;

        if (res->flags & IORESOURCE_PCI_FIXED)
                return false;

        return pdev_resource_assignable(dev, res);
}

/* Sort resources by alignment */
static void pdev_sort_resources(struct pci_dev *dev, struct list_head *head)
{
        struct resource *r;
        int i;

        if (!pdev_resources_assignable(dev))
                return;

        pci_dev_for_each_resource(dev, r, i) {
                const char *r_name = pci_resource_name(dev, i);
                struct pci_dev_resource *dev_res, *tmp;
                resource_size_t r_align;
                struct list_head *n;

                if (!pdev_resource_should_fit(dev, r))
                        continue;

                r_align = pci_resource_alignment(dev, r);
                if (!r_align) {
                        pci_warn(dev, "%s %pR: alignment must not be zero\n",
                                 r_name, r);
                        continue;
                }

                tmp = kzalloc_obj(*tmp);
                if (!tmp)
                        panic("%s: kzalloc() failed!\n", __func__);
                tmp->res = r;
                tmp->dev = dev;
                tmp->start = r->start;
                tmp->end = r->end;
                tmp->flags = r->flags;

                /* Fallback is smallest one or list is empty */
                n = head;
                list_for_each_entry(dev_res, head, list) {
                        resource_size_t align;

                        align = pci_resource_alignment(dev_res->dev,
                                                         dev_res->res);

                        if (r_align > align) {
                                n = &dev_res->list;
                                break;
                        }
                }
                /* Insert it just before n */
                list_add_tail(&tmp->list, n);
        }
}

bool pci_resource_is_optional(const struct pci_dev *dev, int resno)
{
        const struct resource *res = pci_resource_n(dev, resno);

        if (pci_resource_is_iov(resno))
                return true;
        if (resno == PCI_ROM_RESOURCE && !(res->flags & IORESOURCE_ROM_ENABLE))
                return true;
        if (pci_resource_is_bridge_win(resno) && !resource_size(res))
                return true;

        return false;
}

static void reset_resource(struct pci_dev *dev, struct resource *res)
{
        int idx = pci_resource_num(dev, res);
        const char *res_name = pci_resource_name(dev, idx);

        if (pci_resource_is_bridge_win(idx)) {
                res->flags |= IORESOURCE_UNSET;
                return;
        }

        pci_dbg(dev, "%s %pR: resetting resource\n", res_name, res);

        res->start = 0;
        res->end = 0;
        res->flags = 0;
}

/**
 * reassign_resources_sorted() - Satisfy any additional resource requests
 *
 * @realloc_head:       Head of the list tracking requests requiring
 *                      additional resources
 * @head:               Head of the list tracking requests with allocated
 *                      resources
 *
 * Walk through each element of the realloc_head and try to procure additional
 * resources for the element, provided the element is in the head list.
 */
static void reassign_resources_sorted(struct list_head *realloc_head,
                                      struct list_head *head)
{
        struct pci_dev_resource *add_res, *tmp;
        struct pci_dev *dev;
        struct resource *res;
        const char *res_name;
        resource_size_t add_size, align;
        int idx;

        list_for_each_entry_safe(add_res, tmp, realloc_head, list) {
                res = add_res->res;
                dev = add_res->dev;
                idx = pci_resource_num(dev, res);

                /*
                 * Skip resource that failed the earlier assignment and is
                 * not optional as it would just fail again.
                 */
                if (!resource_assigned(res) && resource_size(res) &&
                    !pci_resource_is_optional(dev, idx))
                        goto out;

                /* Skip this resource if not found in head list */
                if (!res_to_dev_res(head, res))
                        continue;

                res_name = pci_resource_name(dev, idx);
                add_size = add_res->add_size;
                align = add_res->min_align;
                if (!resource_assigned(res)) {
                        resource_set_range(res, align,
                                           resource_size(res) + add_size);
                        if (pci_assign_resource(dev, idx)) {
                                pci_dbg(dev,
                                        "%s %pR: ignoring failure in optional allocation\n",
                                        res_name, res);
                        }
                } else if (add_size > 0 || !IS_ALIGNED(res->start, align)) {
                        res->flags |= add_res->flags &
                                 (IORESOURCE_STARTALIGN|IORESOURCE_SIZEALIGN);
                        if (pci_reassign_resource(dev, idx, add_size, align))
                                pci_info(dev, "%s %pR: failed to add optional %llx\n",
                                         res_name, res,
                                         (unsigned long long) add_size);
                }
out:
                list_del(&add_res->list);
                kfree(add_res);
        }
}

/**
 * assign_requested_resources_sorted() - Satisfy resource requests
 *
 * @head:       Head of the list tracking requests for resources
 * @fail_head:  Head of the list tracking requests that could not be
 *              allocated
 * @optional:   Assign also optional resources
 *
 * Satisfy resource requests of each element in the list.  Add requests that
 * could not be satisfied to the failed_list.
 */
static void assign_requested_resources_sorted(struct list_head *head,
                                              struct list_head *fail_head,
                                              bool optional)
{
        struct pci_dev_resource *dev_res;
        struct resource *res;
        struct pci_dev *dev;
        bool optional_res;
        int idx;

        list_for_each_entry(dev_res, head, list) {
                res = dev_res->res;
                dev = dev_res->dev;
                idx = pci_resource_num(dev, res);
                optional_res = pci_resource_is_optional(dev, idx);

                if (!resource_size(res))
                        continue;

                if (!optional && optional_res)
                        continue;

                if (pci_assign_resource(dev, idx)) {
                        if (fail_head) {
                                pci_dev_res_add_to_list(fail_head, dev, res,
                                                        0 /* don't care */,
                                                        0 /* don't care */);
                        }
                }
        }
}

static unsigned long pci_fail_res_type_mask(struct list_head *fail_head)
{
        struct pci_dev_resource *fail_res;
        unsigned long mask = 0;

        /* Check failed type */
        list_for_each_entry(fail_res, fail_head, list)
                mask |= fail_res->flags;

        /*
         * One pref failed resource will set IORESOURCE_MEM, as we can
         * allocate pref in non-pref range.  Will release all assigned
         * non-pref sibling resources according to that bit.
         */
        return mask & (IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_PREFETCH);
}

static bool pci_need_to_release(unsigned long mask, struct resource *res)
{
        if (res->flags & IORESOURCE_IO)
                return !!(mask & IORESOURCE_IO);

        /* Check pref at first */
        if (res->flags & IORESOURCE_PREFETCH) {
                if (mask & IORESOURCE_PREFETCH)
                        return true;
                /* Count pref if its parent is non-pref */
                else if ((mask & IORESOURCE_MEM) &&
                         !(res->parent->flags & IORESOURCE_PREFETCH))
                        return true;
                else
                        return false;
        }

        if (res->flags & IORESOURCE_MEM)
                return !!(mask & IORESOURCE_MEM);

        return false;   /* Should not get here */
}

/* Return: @true if assignment of a required resource failed. */
static bool pci_required_resource_failed(struct list_head *fail_head,
                                         unsigned long type)
{
        struct pci_dev_resource *fail_res;

        type &= PCI_RES_TYPE_MASK;

        list_for_each_entry(fail_res, fail_head, list) {
                int idx = pci_resource_num(fail_res->dev, fail_res->res);

                if (type && (fail_res->flags & PCI_RES_TYPE_MASK) != type)
                        continue;

                if (!pci_resource_is_optional(fail_res->dev, idx))
                        return true;
        }
        return false;
}

static void __assign_resources_sorted(struct list_head *head,
                                      struct list_head *realloc_head,
                                      struct list_head *fail_head)
{
        /*
         * Should not assign requested resources at first.  They could be
         * adjacent, so later reassign can not reallocate them one by one in
         * parent resource window.
         *
         * Try to assign required and any optional resources at beginning
         * (add_size included). If all required resources were successfully
         * assigned, get out early. If could not do that, we still try to
         * assign required at first, then try to reassign some optional
         * resources.
         *
         * Separate three resource type checking if we need to release
         * assigned resource after requested + add_size try.
         *
         *      1. If IO port assignment fails, will release assigned IO
         *         port.
         *      2. If pref MMIO assignment fails, release assigned pref
         *         MMIO.  If assigned pref MMIO's parent is non-pref MMIO
         *         and non-pref MMIO assignment fails, will release that
         *         assigned pref MMIO.
         *      3. If non-pref MMIO assignment fails or pref MMIO
         *         assignment fails, will release assigned non-pref MMIO.
         */
        LIST_HEAD(save_head);
        LIST_HEAD(local_fail_head);
        LIST_HEAD(dummy_head);
        struct pci_dev_resource *save_res;
        struct pci_dev_resource *dev_res, *tmp_res, *dev_res2, *addsize_res;
        struct resource *res;
        struct pci_dev *dev;
        unsigned long fail_type;
        resource_size_t align;

        if (!realloc_head)
                realloc_head = &dummy_head;

        /* Check if optional add_size is there */
        if (list_empty(realloc_head))
                goto assign;

        /* Save original start, end, flags etc at first */
        list_for_each_entry(dev_res, head, list) {
                if (pci_dev_res_add_to_list(&save_head, dev_res->dev,
                                            dev_res->res, 0, 0)) {
                        pci_dev_res_free_list(&save_head);
                        goto assign;
                }
        }

        /* Update res in head list with add_size in realloc_head list */
        list_for_each_entry_safe(dev_res, tmp_res, head, list) {
                res = dev_res->res;

                addsize_res = res_to_dev_res(realloc_head, res);
                if (!addsize_res)
                        continue;

                res->end += addsize_res->add_size;
                /*
                 * There are two kinds of additional resources in the list:
                 * 1. bridge resource  -- IORESOURCE_STARTALIGN
                 * 2. SR-IOV resource  -- IORESOURCE_SIZEALIGN
                 * Here just fix the additional alignment for bridge
                 */
                if (!(res->flags & IORESOURCE_STARTALIGN))
                        continue;

                if (addsize_res->min_align <= res->start)
                        continue;
                /*
                 * The "head" list is sorted by alignment so resources with
                 * bigger alignment will be assigned first.  After we
                 * change the alignment of a dev_res in "head" list, we
                 * need to reorder the list by alignment to make it
                 * consistent.
                 */
                resource_set_range(res, addsize_res->min_align,
                                   resource_size(res));

                list_for_each_entry(dev_res2, head, list) {
                        align = pci_resource_alignment(dev_res2->dev,
                                                       dev_res2->res);
                        if (addsize_res->min_align > align) {
                                list_move_tail(&dev_res->list, &dev_res2->list);
                                break;
                        }
                }

        }

assign:
        assign_requested_resources_sorted(head, &local_fail_head, true);

        /* All non-optional resources assigned? */
        if (list_empty(&local_fail_head)) {
                /* Remove head list from realloc_head list */
                list_for_each_entry(dev_res, head, list)
                        pci_dev_res_remove_from_list(realloc_head,
                                                     dev_res->res);
                pci_dev_res_free_list(&save_head);
                goto out;
        }

        /* Without realloc_head and only optional fails, nothing more to do. */
        if (!pci_required_resource_failed(&local_fail_head, 0) &&
            list_empty(realloc_head)) {
                list_for_each_entry(save_res, &save_head, list) {
                        struct resource *res = save_res->res;

                        if (resource_assigned(res))
                                continue;

                        pci_dev_res_restore(save_res);
                }
                pci_dev_res_free_list(&local_fail_head);
                pci_dev_res_free_list(&save_head);
                goto out;
        }

        /* Check failed type */
        fail_type = pci_fail_res_type_mask(&local_fail_head);
        /* Remove not need to be released assigned res from head list etc */
        list_for_each_entry_safe(dev_res, tmp_res, head, list) {
                res = dev_res->res;

                if (resource_assigned(res) &&
                    !pci_need_to_release(fail_type, res)) {
                        /* Remove it from realloc_head list */
                        pci_dev_res_remove_from_list(realloc_head, res);
                        pci_dev_res_remove_from_list(&save_head, res);
                        list_del(&dev_res->list);
                        kfree(dev_res);
                }
        }

        pci_dev_res_free_list(&local_fail_head);
        /* Release assigned resource */
        list_for_each_entry(dev_res, head, list) {
                res = dev_res->res;
                dev = dev_res->dev;

                pci_release_resource(dev, pci_resource_num(dev, res));
                pci_dev_res_restore(dev_res);
        }
        /* Restore start/end/flags from saved list */
        list_for_each_entry(save_res, &save_head, list)
                pci_dev_res_restore(save_res);
        pci_dev_res_free_list(&save_head);

        /* Satisfy the must-have resource requests */
        assign_requested_resources_sorted(head, NULL, false);

        /* Try to satisfy any additional optional resource requests */
        if (!list_empty(realloc_head))
                reassign_resources_sorted(realloc_head, head);

out:
        /* Reset any failed resource, cannot use fail_head as it can be NULL. */
        list_for_each_entry(dev_res, head, list) {
                res = dev_res->res;
                dev = dev_res->dev;

                if (resource_assigned(res))
                        continue;

                if (fail_head) {
                        pci_dev_res_add_to_list(fail_head, dev, res,
                                                0 /* don't care */,
                                                0 /* don't care */);
                }

                reset_resource(dev, res);
        }

        pci_dev_res_free_list(head);
}

static void pdev_assign_resources_sorted(struct pci_dev *dev,
                                         struct list_head *add_head,
                                         struct list_head *fail_head)
{
        LIST_HEAD(head);

        pdev_sort_resources(dev, &head);
        __assign_resources_sorted(&head, add_head, fail_head);

}

static void pbus_assign_resources_sorted(const struct pci_bus *bus,
                                         struct list_head *realloc_head,
                                         struct list_head *fail_head)
{
        struct pci_dev *dev;
        LIST_HEAD(head);

        list_for_each_entry(dev, &bus->devices, bus_list)
                pdev_sort_resources(dev, &head);

        __assign_resources_sorted(&head, realloc_head, fail_head);
}

/*
 * Initialize bridges with base/limit values we have collected.  PCI-to-PCI
 * Bridge Architecture Specification rev. 1.1 (1998) requires that if there
 * are no I/O ports or memory behind the bridge, the corresponding range
 * must be turned off by writing base value greater than limit to the
 * bridge's base/limit registers.
 *
 * Note: care must be taken when updating I/O base/limit registers of
 * bridges which support 32-bit I/O.  This update requires two config space
 * writes, so it's quite possible that an I/O window of the bridge will
 * have some undesirable address (e.g. 0) after the first write.  Ditto
 * 64-bit prefetchable MMIO.
 */
static void pci_setup_bridge_io(struct pci_dev *bridge)
{
        struct resource *res;
        const char *res_name;
        struct pci_bus_region region;
        unsigned long io_mask;
        u8 io_base_lo, io_limit_lo;
        u16 l;
        u32 io_upper16;

        io_mask = PCI_IO_RANGE_MASK;
        if (bridge->io_window_1k)
                io_mask = PCI_IO_1K_RANGE_MASK;

        /* Set up the top and bottom of the PCI I/O segment for this bus */
        res = &bridge->resource[PCI_BRIDGE_IO_WINDOW];
        res_name = pci_resource_name(bridge, PCI_BRIDGE_IO_WINDOW);
        pcibios_resource_to_bus(bridge->bus, &region, res);
        if (resource_assigned(res) && res->flags & IORESOURCE_IO) {
                pci_read_config_word(bridge, PCI_IO_BASE, &l);
                io_base_lo = (region.start >> 8) & io_mask;
                io_limit_lo = (region.end >> 8) & io_mask;
                l = ((u16) io_limit_lo << 8) | io_base_lo;
                /* Set up upper 16 bits of I/O base/limit */
                io_upper16 = (region.end & 0xffff0000) | (region.start >> 16);
                pci_info(bridge, "  %s %pR\n", res_name, res);
        } else {
                /* Clear upper 16 bits of I/O base/limit */
                io_upper16 = 0;
                l = 0x00f0;
        }
        /* Temporarily disable the I/O range before updating PCI_IO_BASE */
        pci_write_config_dword(bridge, PCI_IO_BASE_UPPER16, 0x0000ffff);
        /* Update lower 16 bits of I/O base/limit */
        pci_write_config_word(bridge, PCI_IO_BASE, l);
        /* Update upper 16 bits of I/O base/limit */
        pci_write_config_dword(bridge, PCI_IO_BASE_UPPER16, io_upper16);
}

static void pci_setup_bridge_mmio(struct pci_dev *bridge)
{
        struct resource *res;
        const char *res_name;
        struct pci_bus_region region;
        u32 l;

        /* Set up the top and bottom of the PCI Memory segment for this bus */
        res = &bridge->resource[PCI_BRIDGE_MEM_WINDOW];
        res_name = pci_resource_name(bridge, PCI_BRIDGE_MEM_WINDOW);
        pcibios_resource_to_bus(bridge->bus, &region, res);
        if (resource_assigned(res) && res->flags & IORESOURCE_MEM) {
                l = (region.start >> 16) & 0xfff0;
                l |= region.end & 0xfff00000;
                pci_info(bridge, "  %s %pR\n", res_name, res);
        } else {
                l = 0x0000fff0;
        }
        pci_write_config_dword(bridge, PCI_MEMORY_BASE, l);
}

static void pci_setup_bridge_mmio_pref(struct pci_dev *bridge)
{
        struct resource *res;
        const char *res_name;
        struct pci_bus_region region;
        u32 l, bu, lu;

        /*
         * Clear out the upper 32 bits of PREF limit.  If
         * PCI_PREF_BASE_UPPER32 was non-zero, this temporarily disables
         * PREF range, which is ok.
         */
        pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, 0);

        /* Set up PREF base/limit */
        bu = lu = 0;
        res = &bridge->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
        res_name = pci_resource_name(bridge, PCI_BRIDGE_PREF_MEM_WINDOW);
        pcibios_resource_to_bus(bridge->bus, &region, res);
        if (resource_assigned(res) && res->flags & IORESOURCE_PREFETCH) {
                l = (region.start >> 16) & 0xfff0;
                l |= region.end & 0xfff00000;
                if (res->flags & IORESOURCE_MEM_64) {
                        bu = upper_32_bits(region.start);
                        lu = upper_32_bits(region.end);
                }
                pci_info(bridge, "  %s %pR\n", res_name, res);
        } else {
                l = 0x0000fff0;
        }
        pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, l);

        /* Set the upper 32 bits of PREF base & limit */
        pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, bu);
        pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, lu);
}

static void __pci_setup_bridge(struct pci_bus *bus, unsigned long type)
{
        struct pci_dev *bridge = bus->self;

        pci_info(bridge, "PCI bridge to %pR\n", &bus->busn_res);

        if (type & IORESOURCE_IO)
                pci_setup_bridge_io(bridge);

        if (type & IORESOURCE_MEM)
                pci_setup_bridge_mmio(bridge);

        if (type & IORESOURCE_PREFETCH)
                pci_setup_bridge_mmio_pref(bridge);

        pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, bus->bridge_ctl);
}

static void pci_setup_one_bridge_window(struct pci_dev *bridge, int resno)
{
        switch (resno) {
        case PCI_BRIDGE_IO_WINDOW:
                pci_setup_bridge_io(bridge);
                break;
        case PCI_BRIDGE_MEM_WINDOW:
                pci_setup_bridge_mmio(bridge);
                break;
        case PCI_BRIDGE_PREF_MEM_WINDOW:
                pci_setup_bridge_mmio_pref(bridge);
                break;
        default:
                return;
        }
}

void __weak pcibios_setup_bridge(struct pci_bus *bus, unsigned long type)
{
}

static void pci_setup_bridge(struct pci_bus *bus)
{
        unsigned long type = IORESOURCE_IO | IORESOURCE_MEM |
                                  IORESOURCE_PREFETCH;

        pcibios_setup_bridge(bus, type);
        __pci_setup_bridge(bus, type);
}


int pci_claim_bridge_resource(struct pci_dev *bridge, int i)
{
        int ret = -EINVAL;

        if (!pci_resource_is_bridge_win(i))
                return 0;

        if (pci_claim_resource(bridge, i) == 0)
                return 0;       /* Claimed the window */

        if ((bridge->class >> 8) != PCI_CLASS_BRIDGE_PCI)
                return 0;

        if (i > PCI_BRIDGE_PREF_MEM_WINDOW)
                return -EINVAL;

        /* Try to clip the resource and claim the smaller window */
        if (pci_bus_clip_resource(bridge, i))
                ret = pci_claim_resource(bridge, i);

        pci_setup_one_bridge_window(bridge, i);

        return ret;
}

/*
 * Check whether the bridge supports optional I/O and prefetchable memory
 * ranges.  If not, the respective base/limit registers must be read-only
 * and read as 0.
 */
static void pci_bridge_check_ranges(struct pci_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        struct resource *b_res;

        b_res = &bridge->resource[PCI_BRIDGE_MEM_WINDOW];
        b_res->flags |= IORESOURCE_MEM;

        if (bridge->io_window) {
                b_res = &bridge->resource[PCI_BRIDGE_IO_WINDOW];
                b_res->flags |= IORESOURCE_IO;
        }

        if (bridge->pref_window) {
                b_res = &bridge->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
                b_res->flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH;
                if (bridge->pref_64_window) {
                        b_res->flags |= IORESOURCE_MEM_64 |
                                        PCI_PREF_RANGE_TYPE_64;
                }
        }
}

static resource_size_t calculate_iosize(resource_size_t size,
                                        resource_size_t min_size,
                                        resource_size_t size1,
                                        resource_size_t add_size,
                                        resource_size_t children_add_size,
                                        resource_size_t old_size,
                                        resource_size_t align)
{
        if (size < min_size)
                size = min_size;
        if (old_size == 1)
                old_size = 0;
        /*
         * To be fixed in 2.5: we should have sort of HAVE_ISA flag in the
         * struct pci_bus.
         */
#if defined(CONFIG_ISA) || defined(CONFIG_EISA)
        size = (size & 0xff) + ((size & ~0xffUL) << 2);
#endif
        size = size + size1;

        size = max(size, add_size) + children_add_size;
        return ALIGN(max(size, old_size), align);
}

static resource_size_t calculate_memsize(resource_size_t size,
                                         resource_size_t min_size,
                                         resource_size_t children_add_size,
                                         resource_size_t align)
{
        size = max(size, min_size) + children_add_size;
        return ALIGN(size, align);
}

resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
                                                unsigned long type)
{
        return 1;
}

#define PCI_P2P_DEFAULT_MEM_ALIGN       SZ_1M
#define PCI_P2P_DEFAULT_IO_ALIGN        SZ_4K
#define PCI_P2P_DEFAULT_IO_ALIGN_1K     SZ_1K

static resource_size_t window_alignment(struct pci_bus *bus, unsigned long type)
{
        resource_size_t align = 1, arch_align;

        if (type & IORESOURCE_MEM)
                align = PCI_P2P_DEFAULT_MEM_ALIGN;
        else if (type & IORESOURCE_IO) {
                /*
                 * Per spec, I/O windows are 4K-aligned, but some bridges have
                 * an extension to support 1K alignment.
                 */
                if (bus->self && bus->self->io_window_1k)
                        align = PCI_P2P_DEFAULT_IO_ALIGN_1K;
                else
                        align = PCI_P2P_DEFAULT_IO_ALIGN;
        }

        arch_align = pcibios_window_alignment(bus, type);
        return max(align, arch_align);
}

/**
 * pbus_size_io() - Size the I/O window of a given bus
 *
 * @bus:                The bus
 * @add_size:           Additional I/O window
 * @realloc_head:       Track the additional I/O window on this list
 *
 * Sizing the I/O windows of the PCI-PCI bridge is trivial, since these
 * windows have 1K or 4K granularity and the I/O ranges of non-bridge PCI
 * devices are limited to 256 bytes.  We must be careful with the ISA
 * aliasing though.
 */
static void pbus_size_io(struct pci_bus *bus, resource_size_t add_size,
                         struct list_head *realloc_head)
{
        struct pci_dev *dev;
        struct resource *b_res = pbus_select_window_for_type(bus, IORESOURCE_IO);
        resource_size_t size = 0, size0 = 0, size1 = 0;
        resource_size_t children_add_size = 0;
        resource_size_t min_align, align;

        if (!b_res)
                return;

        /* If resource is already assigned, nothing more to do */
        if (resource_assigned(b_res))
                return;

        min_align = window_alignment(bus, IORESOURCE_IO);
        list_for_each_entry(dev, &bus->devices, bus_list) {
                struct resource *r;

                pci_dev_for_each_resource(dev, r) {
                        unsigned long r_size;

                        if (resource_assigned(r) || !(r->flags & IORESOURCE_IO))
                                continue;

                        if (!pdev_resource_assignable(dev, r))
                                continue;

                        r_size = resource_size(r);
                        if (r_size < SZ_1K)
                                /* Might be re-aligned for ISA */
                                size += r_size;
                        else
                                size1 += r_size;

                        align = pci_resource_alignment(dev, r);
                        if (align > min_align)
                                min_align = align;

                        if (realloc_head)
                                children_add_size += get_res_add_size(realloc_head, r);
                }
        }

        size0 = calculate_iosize(size, realloc_head ? 0 : add_size, size1, 0, 0,
                        resource_size(b_res), min_align);

        if (size0)
                b_res->flags &= ~IORESOURCE_DISABLED;

        size1 = size0;
        if (realloc_head && (add_size > 0 || children_add_size > 0)) {
                size1 = calculate_iosize(size, 0, size1, add_size,
                                         children_add_size, resource_size(b_res),
                                         min_align);
        }

        if (!size0 && !size1) {
                if (bus->self && (b_res->start || b_res->end))
                        pci_info(bus->self, "disabling bridge window %pR to %pR (unused)\n",
                                 b_res, &bus->busn_res);
                b_res->flags |= IORESOURCE_DISABLED;
                return;
        }

        resource_set_range(b_res, min_align, size0);
        b_res->flags |= IORESOURCE_STARTALIGN;
        if (bus->self && size1 > size0 && realloc_head) {
                b_res->flags &= ~IORESOURCE_DISABLED;
                pci_dev_res_add_to_list(realloc_head, bus->self, b_res,
                                        size1 - size0, min_align);
                pci_info(bus->self, "bridge window %pR to %pR add_size %llx\n",
                         b_res, &bus->busn_res,
                         (unsigned long long) size1 - size0);
        }
}

static inline resource_size_t calculate_mem_align(resource_size_t *aligns,
                                                  int max_order)
{
        resource_size_t align = 0;
        resource_size_t min_align = 0;
        int order;

        for (order = 0; order <= max_order; order++) {
                resource_size_t align1 = 1;

                align1 <<= order + __ffs(SZ_1M);

                if (!align)
                        min_align = align1;
                else if (ALIGN(align + min_align, min_align) < align1)
                        min_align = align1 >> 1;
                align += aligns[order];
        }

        return min_align;
}

/*
 * Calculate bridge window head alignment that leaves no gaps in between
 * resources.
 */
static resource_size_t calculate_head_align(resource_size_t *aligns,
                                            int max_order)
{
        resource_size_t head_align = 1;
        resource_size_t remainder = 0;
        int order;

        /* Take the largest alignment as the starting point. */
        head_align <<= max_order + __ffs(SZ_1M);

        for (order = max_order - 1; order >= 0; order--) {
                resource_size_t align1 = 1;

                align1 <<= order + __ffs(SZ_1M);

                /*
                 * Account smaller resources with alignment < max_order that
                 * could be used to fill head room if alignment less than
                 * max_order is used.
                 */
                remainder += aligns[order];

                /*
                 * Test if head fill is enough to satisfy the alignment of
                 * the larger resources after reducing the alignment.
                 */
                while ((head_align > align1) && (remainder >= head_align / 2)) {
                        head_align /= 2;
                        remainder -= head_align;
                }
        }

        return head_align;
}

/*
 * pbus_size_mem_optional - Account optional resources in bridge window
 *
 * Account an optional resource or the optional part of the resource in bridge
 * window size.
 *
 * Return: %true if the resource is entirely optional.
 */
static bool pbus_size_mem_optional(struct pci_dev *dev, int resno,
                                   resource_size_t align,
                                   struct list_head *realloc_head,
                                   resource_size_t *add_align,
                                   resource_size_t *children_add_size)
{
        struct resource *res = pci_resource_n(dev, resno);
        bool optional = pci_resource_is_optional(dev, resno);
        resource_size_t r_size = resource_size(res);
        struct pci_dev_resource *dev_res = NULL;

        if (!realloc_head)
                return false;

        /*
         * Only bridges have optional sizes in realloc_head at this
         * point. As res_to_dev_res() walks the entire realloc_head
         * list, skip calling it when known unnecessary.
         */
        if (pci_resource_is_bridge_win(resno)) {
                dev_res = res_to_dev_res(realloc_head, res);
                if (dev_res) {
                        *children_add_size += dev_res->add_size;
                        *add_align = max(*add_align, dev_res->min_align);
                }
        }

        if (!optional)
                return false;

        /*
         * Put requested res to the optional list if not there yet (SR-IOV,
         * disabled ROM). Bridge windows with an optional part are already
         * on the list.
         */
        if (!dev_res)
                pci_dev_res_add_to_list(realloc_head, dev, res, 0, align);
        *children_add_size += r_size;
        *add_align = max(align, *add_align);

        return true;
}

/**
 * pbus_size_mem() - Size the memory window of a given bus
 *
 * @bus:                The bus
 * @b_res:              The bridge window resource
 * @add_size:           Additional memory window
 * @realloc_head:       Track the additional memory window on this list
 *
 * Calculate the size of the bridge window @b_res and minimal alignment
 * which guarantees that all child resources fit in this size.
 *
 * Set the bus resource start/end to indicate the required size if there an
 * available unassigned bus resource of the desired @type.
 *
 * Add optional resource requests to the @realloc_head list if it is
 * supplied.
 */
static void pbus_size_mem(struct pci_bus *bus, struct resource *b_res,
                          resource_size_t add_size,
                          struct list_head *realloc_head)
{
        struct pci_dev *dev;
        resource_size_t min_align, win_align, align, size, size0, size1 = 0;
        resource_size_t aligns[28] = {}; /* Alignments from 1MB to 128TB */
        int order, max_order;
        resource_size_t children_add_size = 0;
        resource_size_t add_align = 0;

        if (!b_res)
                return;

        /* If resource is already assigned, nothing more to do */
        if (resource_assigned(b_res))
                return;

        max_order = 0;
        size = 0;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                struct resource *r;
                int i;

                pci_dev_for_each_resource(dev, r, i) {
                        const char *r_name = pci_resource_name(dev, i);
                        resource_size_t r_size;

                        if (!pdev_resources_assignable(dev) ||
                            !pdev_resource_should_fit(dev, r))
                                continue;
                        if (b_res != pbus_select_window(bus, r))
                                continue;

                        align = pci_resource_alignment(dev, r);
                        /*
                         * aligns[0] is for 1MB (since bridge memory
                         * windows are always at least 1MB aligned), so
                         * keep "order" from being negative for smaller
                         * resources.
                         */
                        order = max_t(int, __ffs(align) - __ffs(SZ_1M), 0);
                        if (order >= ARRAY_SIZE(aligns)) {
                                pci_warn(dev, "%s %pR: disabling; bad alignment %#llx\n",
                                         r_name, r, (unsigned long long) align);
                                r->flags = 0;
                                continue;
                        }

                        if (pbus_size_mem_optional(dev, i, align,
                                                   realloc_head, &add_align,
                                                   &children_add_size))
                                continue;

                        r_size = resource_size(r);
                        size += max(r_size, align);

                        aligns[order] += align;
                        if (order > max_order)
                                max_order = order;
                }
        }

        win_align = window_alignment(bus, b_res->flags);
        min_align = calculate_head_align(aligns, max_order);
        min_align = max(min_align, win_align);
        size0 = calculate_memsize(size, realloc_head ? 0 : add_size,
                                  0, win_align);

        if (size0) {
                resource_set_range(b_res, min_align, size0);
                b_res->flags &= ~IORESOURCE_DISABLED;
        }

        if (realloc_head && (add_size > 0 || children_add_size > 0)) {
                add_align = max(min_align, add_align);
                size1 = calculate_memsize(size, add_size, children_add_size,
                                          win_align);
        }

        if (!size0 && !size1) {
                if (bus->self && (b_res->start || b_res->end))
                        pci_info(bus->self, "disabling bridge window %pR to %pR (unused)\n",
                                 b_res, &bus->busn_res);
                b_res->flags |= IORESOURCE_DISABLED;
                return;
        }

        resource_set_range(b_res, min_align, size0);
        b_res->flags |= IORESOURCE_STARTALIGN;
        if (bus->self && realloc_head && (size1 > size0 || add_align > min_align)) {
                b_res->flags &= ~IORESOURCE_DISABLED;
                add_size = size1 > size0 ? size1 - size0 : 0;
                pci_dev_res_add_to_list(realloc_head, bus->self, b_res,
                                        add_size, add_align);
                pci_info(bus->self, "bridge window %pR to %pR add_size %llx add_align %llx\n",
                           b_res, &bus->busn_res,
                           (unsigned long long) add_size,
                           (unsigned long long) add_align);
        }
}

void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
{
        struct pci_dev *dev;
        resource_size_t additional_io_size = 0, additional_mmio_size = 0,
                        additional_mmio_pref_size = 0;
        struct resource *b_res;
        struct pci_host_bridge *host;
        int hdr_type;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                struct pci_bus *b = dev->subordinate;
                if (!b)
                        continue;

                switch (dev->hdr_type) {
                case PCI_HEADER_TYPE_CARDBUS:
                        if (pci_bus_size_cardbus_bridge(b, realloc_head))
                                continue;
                        break;

                case PCI_HEADER_TYPE_BRIDGE:
                default:
                        __pci_bus_size_bridges(b, realloc_head);
                        break;
                }
        }

        /* The root bus? */
        if (pci_is_root_bus(bus)) {
                host = to_pci_host_bridge(bus->bridge);
                if (!host->size_windows)
                        return;
                hdr_type = -1;  /* Intentionally invalid - not a PCI device. */
        } else {
                hdr_type = bus->self->hdr_type;
        }

        switch (hdr_type) {
        case PCI_HEADER_TYPE_CARDBUS:
                /* Don't size CardBuses yet */
                break;

        case PCI_HEADER_TYPE_BRIDGE:
                pci_bridge_check_ranges(bus);
                if (bus->self->is_hotplug_bridge) {
                        additional_io_size  = pci_hotplug_io_size;
                        additional_mmio_size = pci_hotplug_mmio_size;
                        additional_mmio_pref_size = pci_hotplug_mmio_pref_size;
                }
                fallthrough;
        default:
                pbus_size_io(bus, additional_io_size, realloc_head);

                b_res = pbus_select_window_for_type(bus, IORESOURCE_MEM |
                                                         IORESOURCE_PREFETCH |
                                                         IORESOURCE_MEM_64);
                if (b_res && (b_res->flags & IORESOURCE_PREFETCH)) {
                        pbus_size_mem(bus, b_res, additional_mmio_pref_size,
                                      realloc_head);
                }

                b_res = pbus_select_window_for_type(bus, IORESOURCE_MEM);
                if (b_res) {
                        pbus_size_mem(bus, b_res, additional_mmio_size,
                                      realloc_head);
                }
                break;
        }
}

void pci_bus_size_bridges(struct pci_bus *bus)
{
        __pci_bus_size_bridges(bus, NULL);
}
EXPORT_SYMBOL(pci_bus_size_bridges);

static void assign_fixed_resource_on_bus(struct pci_bus *b, struct resource *r)
{
        struct resource *parent_r;
        unsigned long mask = IORESOURCE_IO | IORESOURCE_MEM |
                             IORESOURCE_PREFETCH;

        pci_bus_for_each_resource(b, parent_r) {
                if (!parent_r)
                        continue;

                if ((r->flags & mask) == (parent_r->flags & mask) &&
                    resource_contains(parent_r, r))
                        request_resource(parent_r, r);
        }
}

/*
 * Try to assign any resources marked as IORESOURCE_PCI_FIXED, as they are
 * skipped by pbus_assign_resources_sorted().
 */
static void pdev_assign_fixed_resources(struct pci_dev *dev)
{
        struct resource *r;

        pci_dev_for_each_resource(dev, r) {
                struct pci_bus *b;

                if (resource_assigned(r) ||
                    !(r->flags & IORESOURCE_PCI_FIXED) ||
                    !(r->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
                        continue;

                b = dev->bus;
                while (b && !resource_assigned(r)) {
                        assign_fixed_resource_on_bus(b, r);
                        b = b->parent;
                }
        }
}

void __pci_bus_assign_resources(const struct pci_bus *bus,
                                struct list_head *realloc_head,
                                struct list_head *fail_head)
{
        struct pci_bus *b;
        struct pci_dev *dev;

        pbus_assign_resources_sorted(bus, realloc_head, fail_head);

        list_for_each_entry(dev, &bus->devices, bus_list) {
                pdev_assign_fixed_resources(dev);

                b = dev->subordinate;
                if (!b)
                        continue;

                __pci_bus_assign_resources(b, realloc_head, fail_head);

                switch (dev->hdr_type) {
                case PCI_HEADER_TYPE_BRIDGE:
                        if (!pci_is_enabled(dev))
                                pci_setup_bridge(b);
                        break;

                case PCI_HEADER_TYPE_CARDBUS:
                        pci_setup_cardbus_bridge(b);
                        break;

                default:
                        pci_info(dev, "not setting up bridge for bus %04x:%02x\n",
                                 pci_domain_nr(b), b->number);
                        break;
                }
        }
}

void pci_bus_assign_resources(const struct pci_bus *bus)
{
        __pci_bus_assign_resources(bus, NULL, NULL);
}
EXPORT_SYMBOL(pci_bus_assign_resources);

static void pci_claim_device_resources(struct pci_dev *dev)
{
        int i;

        for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) {
                struct resource *r = &dev->resource[i];

                if (!r->flags || resource_assigned(r))
                        continue;

                pci_claim_resource(dev, i);
        }
}

static void pci_claim_bridge_resources(struct pci_dev *dev)
{
        int i;

        for (i = PCI_BRIDGE_RESOURCES; i < PCI_NUM_RESOURCES; i++) {
                struct resource *r = &dev->resource[i];

                if (!r->flags || resource_assigned(r))
                        continue;
                if (r->flags & IORESOURCE_DISABLED)
                        continue;

                pci_claim_bridge_resource(dev, i);
        }
}

static void pci_bus_allocate_dev_resources(struct pci_bus *b)
{
        struct pci_dev *dev;
        struct pci_bus *child;

        list_for_each_entry(dev, &b->devices, bus_list) {
                pci_claim_device_resources(dev);

                child = dev->subordinate;
                if (child)
                        pci_bus_allocate_dev_resources(child);
        }
}

static void pci_bus_allocate_resources(struct pci_bus *b)
{
        struct pci_bus *child;

        /*
         * Carry out a depth-first search on the PCI bus tree to allocate
         * bridge apertures.  Read the programmed bridge bases and
         * recursively claim the respective bridge resources.
         */
        if (b->self) {
                pci_read_bridge_bases(b);
                pci_claim_bridge_resources(b->self);
        }

        list_for_each_entry(child, &b->children, node)
                pci_bus_allocate_resources(child);
}

void pci_bus_claim_resources(struct pci_bus *b)
{
        pci_bus_allocate_resources(b);
        pci_bus_allocate_dev_resources(b);
}
EXPORT_SYMBOL(pci_bus_claim_resources);

static void __pci_bridge_assign_resources(const struct pci_dev *bridge,
                                          struct list_head *add_head,
                                          struct list_head *fail_head)
{
        struct pci_bus *b;

        pdev_assign_resources_sorted((struct pci_dev *)bridge,
                                         add_head, fail_head);

        b = bridge->subordinate;
        if (!b)
                return;

        __pci_bus_assign_resources(b, add_head, fail_head);

        switch (bridge->class >> 8) {
        case PCI_CLASS_BRIDGE_PCI:
                pci_setup_bridge(b);
                break;

        case PCI_CLASS_BRIDGE_CARDBUS:
                pci_setup_cardbus_bridge(b);
                break;

        default:
                pci_info(bridge, "not setting up bridge for bus %04x:%02x\n",
                         pci_domain_nr(b), b->number);
                break;
        }
}

static void pci_bridge_release_resources(struct pci_bus *bus,
                                         struct resource *b_win)
{
        struct pci_dev *dev = bus->self;
        int idx, ret;

        if (!resource_assigned(b_win))
                return;

        idx = pci_resource_num(dev, b_win);

        /* If there are children, release them all */
        release_child_resources(b_win);

        ret = pci_release_resource(dev, idx);
        if (ret)
                return;

        pci_setup_one_bridge_window(dev, idx);
}

enum release_type {
        leaf_only,
        whole_subtree,
};

/*
 * Try to release PCI bridge resources from leaf bridge, so we can allocate
 * a larger window later.
 */
static void pci_bus_release_bridge_resources(struct pci_bus *bus,
                                             struct resource *b_win,
                                             enum release_type rel_type)
{
        struct pci_dev *dev;
        bool is_leaf_bridge = true;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                struct pci_bus *b = dev->subordinate;
                struct resource *res;

                if (!b)
                        continue;

                is_leaf_bridge = false;

                if ((dev->class >> 8) != PCI_CLASS_BRIDGE_PCI)
                        continue;

                if (rel_type != whole_subtree)
                        continue;

                pci_bus_for_each_resource(b, res) {
                        if (res->parent != b_win)
                                continue;

                        pci_bus_release_bridge_resources(b, res, rel_type);
                }
        }

        if (pci_is_root_bus(bus))
                return;

        if ((bus->self->class >> 8) != PCI_CLASS_BRIDGE_PCI)
                return;

        if ((rel_type == whole_subtree) || is_leaf_bridge)
                pci_bridge_release_resources(bus, b_win);
}

static void pci_bus_dump_res(struct pci_bus *bus)
{
        struct resource *res;
        int i;

        pci_bus_for_each_resource(bus, res, i) {
                if (!res || !res->end || !res->flags)
                        continue;

                dev_info(&bus->dev, "resource %d %pR\n", i, res);
        }
}

static void pci_bus_dump_resources(struct pci_bus *bus)
{
        struct pci_bus *b;
        struct pci_dev *dev;


        pci_bus_dump_res(bus);

        list_for_each_entry(dev, &bus->devices, bus_list) {
                b = dev->subordinate;
                if (!b)
                        continue;

                pci_bus_dump_resources(b);
        }
}

static int pci_bus_get_depth(struct pci_bus *bus)
{
        int depth = 0;
        struct pci_bus *child_bus;

        list_for_each_entry(child_bus, &bus->children, node) {
                int ret;

                ret = pci_bus_get_depth(child_bus);
                if (ret + 1 > depth)
                        depth = ret + 1;
        }

        return depth;
}

/*
 * -1: undefined, will auto detect later
 *  0: disabled by user
 *  1: disabled by auto detect
 *  2: enabled by user
 *  3: enabled by auto detect
 */
enum enable_type {
        undefined = -1,
        user_disabled,
        auto_disabled,
        user_enabled,
        auto_enabled,
};

static enum enable_type pci_realloc_enable = undefined;
void __init pci_realloc_get_opt(char *str)
{
        if (!strncmp(str, "off", 3))
                pci_realloc_enable = user_disabled;
        else if (!strncmp(str, "on", 2))
                pci_realloc_enable = user_enabled;
}
static bool pci_realloc_enabled(enum enable_type enable)
{
        return enable >= user_enabled;
}

#if defined(CONFIG_PCI_IOV) && defined(CONFIG_PCI_REALLOC_ENABLE_AUTO)
static int iov_resources_unassigned(struct pci_dev *dev, void *data)
{
        int i;
        bool *unassigned = data;

        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
                int idx = pci_resource_num_from_vf_bar(i);
                struct resource *r = &dev->resource[idx];
                struct pci_bus_region region;

                /* Not assigned or rejected by kernel? */
                if (!r->flags)
                        continue;

                pcibios_resource_to_bus(dev->bus, &region, r);
                if (!region.start) {
                        *unassigned = true;
                        return 1; /* Return early from pci_walk_bus() */
                }
        }

        return 0;
}

static enum enable_type pci_realloc_detect(struct pci_bus *bus,
                                           enum enable_type enable_local)
{
        bool unassigned = false;
        struct pci_host_bridge *host;

        if (enable_local != undefined)
                return enable_local;

        host = pci_find_host_bridge(bus);
        if (host->preserve_config)
                return auto_disabled;

        pci_walk_bus(bus, iov_resources_unassigned, &unassigned);
        if (unassigned)
                return auto_enabled;

        return enable_local;
}
#else
static enum enable_type pci_realloc_detect(struct pci_bus *bus,
                                           enum enable_type enable_local)
{
        return enable_local;
}
#endif

static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res,
                                 struct list_head *add_list,
                                 resource_size_t new_size)
{
        resource_size_t add_size, size = resource_size(res);

        if (resource_assigned(res))
                return;

        if (!new_size)
                return;

        if (new_size > size) {
                add_size = new_size - size;
                pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
                        &add_size);
        } else if (new_size < size) {
                add_size = size - new_size;
                pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res,
                        &add_size);
        } else {
                return;
        }

        resource_set_size(res, new_size);

        /* If the resource is part of the add_list, remove it now */
        if (add_list)
                pci_dev_res_remove_from_list(add_list, res);
}

static void remove_dev_resource(struct resource *avail, struct pci_dev *dev,
                                struct resource *res)
{
        resource_size_t size, align, tmp;

        size = resource_size(res);
        if (!size)
                return;

        align = pci_resource_alignment(dev, res);
        align = align ? ALIGN(avail->start, align) - avail->start : 0;
        tmp = align + size;
        avail->start = min(avail->start + tmp, avail->end + 1);
}

static void remove_dev_resources(struct pci_dev *dev,
                                 struct resource available[PCI_P2P_BRIDGE_RESOURCE_NUM])
{
        struct resource *res, *b_win;
        int idx;

        pci_dev_for_each_resource(dev, res) {
                b_win = pbus_select_window(dev->bus, res);
                if (!b_win)
                        continue;

                idx = pci_resource_num(dev->bus->self, b_win);
                idx -= PCI_BRIDGE_RESOURCES;

                remove_dev_resource(&available[idx], dev, res);
        }
}

#define ALIGN_DOWN_IF_NONZERO(addr, align) \
                        ((align) ? ALIGN_DOWN((addr), (align)) : (addr))

/*
 * io, mmio and mmio_pref contain the total amount of bridge window space
 * available. This includes the minimal space needed to cover all the
 * existing devices on the bus and the possible extra space that can be
 * shared with the bridges.
 */
static void pci_bus_distribute_available_resources(struct pci_bus *bus,
                    struct list_head *add_list,
                    struct resource available_in[PCI_P2P_BRIDGE_RESOURCE_NUM])
{
        struct resource available[PCI_P2P_BRIDGE_RESOURCE_NUM];
        unsigned int normal_bridges = 0, hotplug_bridges = 0;
        struct pci_dev *dev, *bridge = bus->self;
        resource_size_t per_bridge[PCI_P2P_BRIDGE_RESOURCE_NUM];
        resource_size_t align;
        int i;

        for (i = 0; i < PCI_P2P_BRIDGE_RESOURCE_NUM; i++) {
                struct resource *res =
                        pci_resource_n(bridge, PCI_BRIDGE_RESOURCES + i);

                available[i] = available_in[i];

                /*
                 * The alignment of this bridge is yet to be considered,
                 * hence it must be done now before extending its bridge
                 * window.
                 */
                align = pci_resource_alignment(bridge, res);
                if (!resource_assigned(res) && align)
                        available[i].start = min(ALIGN(available[i].start, align),
                                                 available[i].end + 1);

                /*
                 * Now that we have adjusted for alignment, update the
                 * bridge window resources to fill as much remaining
                 * resource space as possible.
                 */
                adjust_bridge_window(bridge, res, add_list,
                                     resource_size(&available[i]));
        }

        /*
         * Calculate how many hotplug bridges and normal bridges there
         * are on this bus.  We will distribute the additional available
         * resources between hotplug bridges.
         */
        for_each_pci_bridge(dev, bus) {
                if (dev->is_hotplug_bridge)
                        hotplug_bridges++;
                else
                        normal_bridges++;
        }

        if (!(hotplug_bridges + normal_bridges))
                return;

        /*
         * Calculate the amount of space we can forward from "bus" to any
         * downstream buses, i.e., the space left over after assigning the
         * BARs and windows on "bus".
         */
        list_for_each_entry(dev, &bus->devices, bus_list) {
                if (!dev->is_virtfn)
                        remove_dev_resources(dev, available);
        }

        /*
         * If there is at least one hotplug bridge on this bus it gets all
         * the extra resource space that was left after the reductions
         * above.
         *
         * If there are no hotplug bridges the extra resource space is
         * split between non-hotplug bridges. This is to allow possible
         * hotplug bridges below them to get the extra space as well.
         */
        for (i = 0; i < PCI_P2P_BRIDGE_RESOURCE_NUM; i++) {
                per_bridge[i] = div64_ul(resource_size(&available[i]),
                                         hotplug_bridges ?: normal_bridges);
        }

        for_each_pci_bridge(dev, bus) {
                struct resource *res;
                struct pci_bus *b;

                b = dev->subordinate;
                if (!b)
                        continue;
                if (hotplug_bridges && !dev->is_hotplug_bridge)
                        continue;

                for (i = 0; i < PCI_P2P_BRIDGE_RESOURCE_NUM; i++) {
                        res = pci_resource_n(dev, PCI_BRIDGE_RESOURCES + i);

                        /*
                         * Make sure the split resource space is properly
                         * aligned for bridge windows (align it down to
                         * avoid going above what is available).
                         */
                        align = pci_resource_alignment(dev, res);
                        resource_set_size(&available[i],
                                          ALIGN_DOWN_IF_NONZERO(per_bridge[i],
                                                                align));

                        /*
                         * The per_bridge holds the extra resource space
                         * that can be added for each bridge but there is
                         * the minimal already reserved as well so adjust
                         * x.start down accordingly to cover the whole
                         * space.
                         */
                        available[i].start -= resource_size(res);
                }

                pci_bus_distribute_available_resources(b, add_list, available);

                for (i = 0; i < PCI_P2P_BRIDGE_RESOURCE_NUM; i++)
                        available[i].start += available[i].end + 1;
        }
}

static void pci_bridge_distribute_available_resources(struct pci_dev *bridge,
                                                      struct list_head *add_list)
{
        struct resource *res, available[PCI_P2P_BRIDGE_RESOURCE_NUM];
        unsigned int i;

        if (!bridge->is_hotplug_bridge)
                return;

        pci_dbg(bridge, "distributing available resources\n");

        /* Take the initial extra resources from the hotplug port */
        for (i = 0; i < PCI_P2P_BRIDGE_RESOURCE_NUM; i++) {
                res = pci_resource_n(bridge, PCI_BRIDGE_RESOURCES + i);
                available[i] = *res;
        }

        pci_bus_distribute_available_resources(bridge->subordinate,
                                               add_list, available);
}

static bool pci_bridge_resources_not_assigned(struct pci_dev *dev)
{
        const struct resource *r;

        /*
         * If the child device's resources are not yet assigned it means we
         * are configuring them (not the boot firmware), so we should be
         * able to extend the upstream bridge resources in the same way we
         * do with the normal hotplug case.
         */
        r = &dev->resource[PCI_BRIDGE_IO_WINDOW];
        if (r->flags && !(r->flags & IORESOURCE_STARTALIGN))
                return false;
        r = &dev->resource[PCI_BRIDGE_MEM_WINDOW];
        if (r->flags && !(r->flags & IORESOURCE_STARTALIGN))
                return false;
        r = &dev->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
        if (r->flags && !(r->flags & IORESOURCE_STARTALIGN))
                return false;

        return true;
}

static void
pci_root_bus_distribute_available_resources(struct pci_bus *bus,
                                            struct list_head *add_list)
{
        struct pci_dev *dev, *bridge = bus->self;

        for_each_pci_bridge(dev, bus) {
                struct pci_bus *b;

                b = dev->subordinate;
                if (!b)
                        continue;

                /*
                 * Need to check "bridge" here too because it is NULL
                 * in case of root bus.
                 */
                if (bridge && pci_bridge_resources_not_assigned(dev))
                        pci_bridge_distribute_available_resources(dev, add_list);
                else
                        pci_root_bus_distribute_available_resources(b, add_list);
        }
}

static void pci_prepare_next_assign_round(struct list_head *fail_head,
                                          int tried_times,
                                          enum release_type rel_type)
{
        struct pci_dev_resource *fail_res;

        pr_info("PCI: No. %d try to assign unassigned res\n", tried_times + 1);

        /*
         * Try to release leaf bridge's resources that aren't big
         * enough to contain child device resources.
         */
        list_for_each_entry(fail_res, fail_head, list) {
                struct pci_bus *bus = fail_res->dev->bus;
                struct resource *b_win;

                b_win = pbus_select_window_for_type(bus, fail_res->flags);
                if (!b_win)
                        continue;
                pci_bus_release_bridge_resources(bus, b_win, rel_type);
        }

        /* Restore size and flags */
        list_for_each_entry(fail_res, fail_head, list)
                pci_dev_res_restore(fail_res);

        pci_dev_res_free_list(fail_head);
}

/*
 * First try will not touch PCI bridge res.
 * Second and later try will clear small leaf bridge res.
 * Will stop till to the max depth if can not find good one.
 */
void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
{
        LIST_HEAD(realloc_head);
        /* List of resources that want additional resources */
        struct list_head *add_list = NULL;
        int tried_times = 0;
        enum release_type rel_type = leaf_only;
        LIST_HEAD(fail_head);
        int pci_try_num = 1;
        enum enable_type enable_local;

        /* Don't realloc if asked to do so */
        enable_local = pci_realloc_detect(bus, pci_realloc_enable);
        if (pci_realloc_enabled(enable_local)) {
                int max_depth = pci_bus_get_depth(bus);

                pci_try_num = max_depth + 1;
                dev_info(&bus->dev, "max bus depth: %d pci_try_num: %d\n",
                         max_depth, pci_try_num);
        }

        while (1) {
                /*
                 * Last try will use add_list, otherwise will try good to
                 * have as must have, so can realloc parent bridge resource
                 */
                if (tried_times + 1 == pci_try_num)
                        add_list = &realloc_head;
                /*
                 * Depth first, calculate sizes and alignments of all
                 * subordinate buses.
                 */
                __pci_bus_size_bridges(bus, add_list);

                pci_root_bus_distribute_available_resources(bus, add_list);

                /* Depth last, allocate resources and update the hardware. */
                __pci_bus_assign_resources(bus, add_list, &fail_head);
                if (WARN_ON_ONCE(add_list && !list_empty(add_list)))
                        pci_dev_res_free_list(add_list);
                tried_times++;

                /* Any device complain? */
                if (list_empty(&fail_head))
                        break;

                if (tried_times >= pci_try_num) {
                        if (enable_local == undefined) {
                                dev_info(&bus->dev,
                                         "Some PCI device resources are unassigned, try booting with pci=realloc\n");
                        } else if (enable_local == auto_enabled) {
                                dev_info(&bus->dev,
                                         "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
                        }
                        pci_dev_res_free_list(&fail_head);
                        break;
                }

                /* Third times and later will not check if it is leaf */
                if (tried_times + 1 > 2)
                        rel_type = whole_subtree;

                pci_prepare_next_assign_round(&fail_head, tried_times, rel_type);
        }

        pci_bus_dump_resources(bus);
}

void pci_assign_unassigned_resources(void)
{
        struct pci_bus *root_bus;

        list_for_each_entry(root_bus, &pci_root_buses, node) {
                pci_assign_unassigned_root_bus_resources(root_bus);

                /* Make sure the root bridge has a companion ACPI device */
                if (ACPI_HANDLE(root_bus->bridge))
                        acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
        }
}

void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
{
        struct pci_bus *parent = bridge->subordinate;
        /* List of resources that want additional resources */
        LIST_HEAD(add_list);
        int tried_times = 0;
        LIST_HEAD(fail_head);
        int ret;

        while (1) {
                __pci_bus_size_bridges(parent, &add_list);

                /*
                 * Distribute remaining resources (if any) equally between
                 * hotplug bridges below. This makes it possible to extend
                 * the hierarchy later without running out of resources.
                 */
                pci_bridge_distribute_available_resources(bridge, &add_list);

                __pci_bridge_assign_resources(bridge, &add_list, &fail_head);
                if (WARN_ON_ONCE(!list_empty(&add_list)))
                        pci_dev_res_free_list(&add_list);
                tried_times++;

                if (list_empty(&fail_head))
                        break;

                if (tried_times >= 2) {
                        /* Still fail, don't need to try more */
                        pci_dev_res_free_list(&fail_head);
                        break;
                }

                pci_prepare_next_assign_round(&fail_head, tried_times,
                                              whole_subtree);
        }

        ret = pci_reenable_device(bridge);
        if (ret)
                pci_err(bridge, "Error reenabling bridge (%d)\n", ret);
        pci_set_master(bridge);
}
EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);

/*
 * Walk to the root bus, find the bridge window relevant for @res and
 * release it when possible. If the bridge window contains assigned
 * resources, it cannot be released.
 */
static int pbus_reassign_bridge_resources(struct pci_bus *bus, struct resource *res,
                                          struct list_head *saved)
{
        unsigned long type = res->flags;
        struct pci_dev_resource *dev_res;
        struct pci_dev *bridge = NULL;
        LIST_HEAD(added);
        LIST_HEAD(failed);
        unsigned int i;
        int ret = 0;

        while (!pci_is_root_bus(bus)) {
                bridge = bus->self;
                res = pbus_select_window(bus, res);
                if (!res)
                        break;

                i = pci_resource_num(bridge, res);

                /* Ignore BARs which are still in use */
                if (!res->child) {
                        ret = pci_dev_res_add_to_list(saved, bridge, res, 0, 0);
                        if (ret)
                                return ret;

                        pci_release_resource(bridge, i);
                } else {
                        const char *res_name = pci_resource_name(bridge, i);

                        pci_warn(bridge,
                                 "%s %pR: was not released (still contains assigned resources)\n",
                                 res_name, res);
                }

                bus = bus->parent;
        }

        if (!bridge)
                return -ENOENT;

        __pci_bus_size_bridges(bridge->subordinate, &added);
        __pci_bridge_assign_resources(bridge, &added, &failed);
        if (WARN_ON_ONCE(!list_empty(&added)))
                pci_dev_res_free_list(&added);

        if (!list_empty(&failed)) {
                if (pci_required_resource_failed(&failed, type))
                        ret = -ENOSPC;
                pci_dev_res_free_list(&failed);
                if (ret)
                        return ret;

                /* Only resources with unrelated types failed (again) */
        }

        list_for_each_entry(dev_res, saved, list) {
                struct pci_dev *dev = dev_res->dev;

                /* Skip the bridge we just assigned resources for */
                if (bridge == dev)
                        continue;

                if (!dev->subordinate)
                        continue;

                pci_setup_bridge(dev->subordinate);
        }

        return 0;
}

int pci_do_resource_release_and_resize(struct pci_dev *pdev, int resno, int size,
                                       int exclude_bars)
{
        struct resource *res = pci_resource_n(pdev, resno);
        struct pci_dev_resource *dev_res;
        struct pci_bus *bus = pdev->bus;
        struct resource *b_win, *r;
        LIST_HEAD(saved);
        unsigned int i;
        int old, ret;

        b_win = pbus_select_window(bus, res);
        if (!b_win)
                return -EINVAL;

        old = pci_rebar_get_current_size(pdev, resno);
        if (old < 0)
                return old;

        ret = pci_rebar_set_size(pdev, resno, size);
        if (ret)
                return ret;

        pci_dev_for_each_resource(pdev, r, i) {
                if (i >= PCI_BRIDGE_RESOURCES)
                        break;

                if (exclude_bars & BIT(i))
                        continue;

                if (b_win != pbus_select_window(bus, r))
                        continue;

                ret = pci_dev_res_add_to_list(&saved, pdev, r, 0, 0);
                if (ret)
                        goto restore;
                pci_release_resource(pdev, i);
        }

        pci_resize_resource_set_size(pdev, resno, size);

        if (!bus->self)
                goto out;

        down_read(&pci_bus_sem);
        ret = pbus_reassign_bridge_resources(bus, res, &saved);
        if (ret)
                goto restore;

out:
        up_read(&pci_bus_sem);
        pci_dev_res_free_list(&saved);
        return ret;

restore:
        /*
         * Revert to the old configuration.
         *
         * BAR Size must be restored first because it affects the read-only
         * bits in BAR (the old address might not be restorable otherwise
         * due to low address bits).
         */
        pci_rebar_set_size(pdev, resno, old);

        list_for_each_entry(dev_res, &saved, list) {
                struct resource *res = dev_res->res;
                struct pci_dev *dev = dev_res->dev;

                i = pci_resource_num(dev, res);

                if (resource_assigned(res)) {
                        release_child_resources(res);
                        pci_release_resource(dev, i);
                }

                pci_dev_res_restore(dev_res);

                if (pci_claim_resource(dev, i))
                        continue;

                if (i < PCI_BRIDGE_RESOURCES) {
                        const char *res_name = pci_resource_name(dev, i);

                        pci_update_resource(dev, i);
                        pci_info(dev, "%s %pR: old value restored\n",
                                 res_name, res);
                }
                if (dev->subordinate)
                        pci_setup_bridge(dev->subordinate);
        }
        goto out;
}

void pci_assign_unassigned_bus_resources(struct pci_bus *bus)
{
        struct pci_dev *dev;
        /* List of resources that want additional resources */
        LIST_HEAD(add_list);

        down_read(&pci_bus_sem);
        for_each_pci_bridge(dev, bus)
                if (pci_has_subordinate(dev))
                        __pci_bus_size_bridges(dev->subordinate, &add_list);
        up_read(&pci_bus_sem);
        __pci_bus_assign_resources(bus, &add_list, NULL);
        if (WARN_ON_ONCE(!list_empty(&add_list)))
                pci_dev_res_free_list(&add_list);
}
EXPORT_SYMBOL_GPL(pci_assign_unassigned_bus_resources);