PCI: Delay enabling bridges until they're needed

[mirror_ubuntu-zesty-kernel.git] / drivers / pci / setup-bus.c

/*
 *      drivers/pci/setup-bus.c
 *
 * Extruded from code written by
 *      Dave Rusling (david.rusling@reo.mts.dec.com)
 *      David Mosberger (davidm@cs.arizona.edu)
 *      David Miller (davem@redhat.com)
 *
 * Support routines for initializing a PCI subsystem.
 */

/*
 * 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/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <asm-generic/pci-bridge.h>
#include "pci.h"

unsigned int 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 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);
        }
}

/**
 * add_to_list() - add a new resource tracker to the list
 * @head:       Head of the list
 * @dev:        device corresponding to which the resource
 *              belongs
 * @res:        The resource to be tracked
 * @add_size:   additional size to be optionally added
 *              to the resource
 */
static int 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(sizeof(*tmp), GFP_KERNEL);
        if (!tmp) {
                pr_warning("add_to_list: kmalloc() failed!\n");
                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 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 resource_size_t get_res_add_size(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) {
                        int idx = res - &dev_res->dev->resource[0];

                        dev_printk(KERN_DEBUG, &dev_res->dev->dev,
                                 "res[%d]=%pR get_res_add_size add_size %llx\n",
                                 idx, dev_res->res,
                                 (unsigned long long)dev_res->add_size);

                        return dev_res->add_size;
                }
        }

        return 0;
}

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

        for (i = 0; i < PCI_NUM_RESOURCES; i++) {
                struct resource *r;
                struct pci_dev_resource *dev_res, *tmp;
                resource_size_t r_align;
                struct list_head *n;

                r = &dev->resource[i];

                if (r->flags & IORESOURCE_PCI_FIXED)
                        continue;

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

                r_align = pci_resource_alignment(dev, r);
                if (!r_align) {
                        dev_warn(&dev->dev, "BAR %d: %pR has bogus alignment\n",
                                 i, r);
                        continue;
                }

                tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
                if (!tmp)
                        panic("pdev_sort_resources(): "
                              "kmalloc() failed!\n");
                tmp->res = r;
                tmp->dev = dev;

                /* 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);
        }
}

static void __dev_sort_resources(struct pci_dev *dev,
                                 struct list_head *head)
{
        u16 class = dev->class >> 8;

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

        /* Don't touch ioapic devices already enabled by firmware */
        if (class == PCI_CLASS_SYSTEM_PIC) {
                u16 command;
                pci_read_config_word(dev, PCI_COMMAND, &command);
                if (command & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
                        return;
        }

        pdev_sort_resources(dev, head);
}

static inline void reset_resource(struct resource *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 resource *res;
        struct pci_dev_resource *add_res, *tmp;
        struct pci_dev_resource *dev_res;
        resource_size_t add_size;
        int idx;

        list_for_each_entry_safe(add_res, tmp, realloc_head, list) {
                bool found_match = false;

                res = add_res->res;
                /* skip resource that has been reset */
                if (!res->flags)
                        goto out;

                /* skip this resource if not found in head list */
                list_for_each_entry(dev_res, head, list) {
                        if (dev_res->res == res) {
                                found_match = true;
                                break;
                        }
                }
                if (!found_match)/* just skip */
                        continue;

                idx = res - &add_res->dev->resource[0];
                add_size = add_res->add_size;
                if (!resource_size(res)) {
                        res->start = add_res->start;
                        res->end = res->start + add_size - 1;
                        if (pci_assign_resource(add_res->dev, idx))
                                reset_resource(res);
                } else {
                        resource_size_t align = add_res->min_align;
                        res->flags |= add_res->flags &
                                 (IORESOURCE_STARTALIGN|IORESOURCE_SIZEALIGN);
                        if (pci_reassign_resource(add_res->dev, idx,
                                                  add_size, align))
                                dev_printk(KERN_DEBUG, &add_res->dev->dev,
                                           "failed to add %llx res[%d]=%pR\n",
                                           (unsigned long long)add_size,
                                           idx, res);
                }
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
 *
 * Satisfy resource requests of each element in the list. Add
 * requests that could not satisfied to the failed_list.
 */
static void assign_requested_resources_sorted(struct list_head *head,
                                 struct list_head *fail_head)
{
        struct resource *res;
        struct pci_dev_resource *dev_res;
        int idx;

        list_for_each_entry(dev_res, head, list) {
                res = dev_res->res;
                idx = res - &dev_res->dev->resource[0];
                if (resource_size(res) &&
                    pci_assign_resource(dev_res->dev, idx)) {
                        if (fail_head) {
                                /*
                                 * if the failed res is for ROM BAR, and it will
                                 * be enabled later, don't add it to the list
                                 */
                                if (!((idx == PCI_ROM_RESOURCE) &&
                                      (!(res->flags & IORESOURCE_ROM_ENABLE))))
                                        add_to_list(fail_head,
                                                    dev_res->dev, res,
                                                    0 /* dont care */,
                                                    0 /* dont care */);
                        }
                        reset_resource(res);
                }
        }
}

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 requested + add_size at beginning
         *  if could do that, could get out early.
         *  if could not do that, we still try to assign requested at first,
         *    then try to reassign add_size for some resources.
         */
        LIST_HEAD(save_head);
        LIST_HEAD(local_fail_head);
        struct pci_dev_resource *save_res;
        struct pci_dev_resource *dev_res;

        /* Check if optional add_size is there */
        if (!realloc_head || list_empty(realloc_head))
                goto requested_and_reassign;

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

        /* Update res in head list with add_size in realloc_head list */
        list_for_each_entry(dev_res, head, list)
                dev_res->res->end += get_res_add_size(realloc_head,
                                                        dev_res->res);

        /* Try updated head list with add_size added */
        assign_requested_resources_sorted(head, &local_fail_head);

        /* all assigned with add_size ? */
        if (list_empty(&local_fail_head)) {
                /* Remove head list from realloc_head list */
                list_for_each_entry(dev_res, head, list)
                        remove_from_list(realloc_head, dev_res->res);
                free_list(&save_head);
                free_list(head);
                return;
        }

        free_list(&local_fail_head);
        /* Release assigned resource */
        list_for_each_entry(dev_res, head, list)
                if (dev_res->res->parent)
                        release_resource(dev_res->res);
        /* Restore start/end/flags from saved list */
        list_for_each_entry(save_res, &save_head, list) {
                struct resource *res = save_res->res;

                res->start = save_res->start;
                res->end = save_res->end;
                res->flags = save_res->flags;
        }
        free_list(&save_head);

requested_and_reassign:
        /* Satisfy the must-have resource requests */
        assign_requested_resources_sorted(head, fail_head);

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

        __dev_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)
                __dev_sort_resources(dev, &head);

        __assign_resources_sorted(&head, realloc_head, fail_head);
}

void pci_setup_cardbus(struct pci_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        struct resource *res;
        struct pci_bus_region region;

        dev_info(&bridge->dev, "CardBus bridge to %pR\n",
                 &bus->busn_res);

        res = bus->resource[0];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_IO) {
                /*
                 * The IO resource is allocated a range twice as large as it
                 * would normally need.  This allows us to set both IO regs.
                 */
                dev_info(&bridge->dev, "  bridge window %pR\n", res);
                pci_write_config_dword(bridge, PCI_CB_IO_BASE_0,
                                        region.start);
                pci_write_config_dword(bridge, PCI_CB_IO_LIMIT_0,
                                        region.end);
        }

        res = bus->resource[1];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_IO) {
                dev_info(&bridge->dev, "  bridge window %pR\n", res);
                pci_write_config_dword(bridge, PCI_CB_IO_BASE_1,
                                        region.start);
                pci_write_config_dword(bridge, PCI_CB_IO_LIMIT_1,
                                        region.end);
        }

        res = bus->resource[2];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_MEM) {
                dev_info(&bridge->dev, "  bridge window %pR\n", res);
                pci_write_config_dword(bridge, PCI_CB_MEMORY_BASE_0,
                                        region.start);
                pci_write_config_dword(bridge, PCI_CB_MEMORY_LIMIT_0,
                                        region.end);
        }

        res = bus->resource[3];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_MEM) {
                dev_info(&bridge->dev, "  bridge window %pR\n", res);
                pci_write_config_dword(bridge, PCI_CB_MEMORY_BASE_1,
                                        region.start);
                pci_write_config_dword(bridge, PCI_CB_MEMORY_LIMIT_1,
                                        region.end);
        }
}
EXPORT_SYMBOL(pci_setup_cardbus);

/* Initialize bridges with base/limit values we have collected.
   PCI-to-PCI Bridge Architecture Specification rev. 1.1 (1998)
   requires that if there is no I/O ports or memory behind the
   bridge, 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_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        struct resource *res;
        struct pci_bus_region region;
        unsigned long io_mask;
        u8 io_base_lo, io_limit_lo;
        u32 l, 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 = bus->resource[0];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_IO) {
                pci_read_config_dword(bridge, PCI_IO_BASE, &l);
                l &= 0xffff0000;
                io_base_lo = (region.start >> 8) & io_mask;
                io_limit_lo = (region.end >> 8) & io_mask;
                l |= ((u32) 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);
                dev_info(&bridge->dev, "  bridge window %pR\n", 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_dword(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_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        struct resource *res;
        struct pci_bus_region region;
        u32 l;

        /* Set up the top and bottom of the PCI Memory segment for this bus. */
        res = bus->resource[1];
        pcibios_resource_to_bus(bridge, &region, res);
        if (res->flags & IORESOURCE_MEM) {
                l = (region.start >> 16) & 0xfff0;
                l |= region.end & 0xfff00000;
                dev_info(&bridge->dev, "  bridge window %pR\n", res);
        } else {
                l = 0x0000fff0;
        }
        pci_write_config_dword(bridge, PCI_MEMORY_BASE, l);
}

static void pci_setup_bridge_mmio_pref(struct pci_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        struct resource *res;
        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 = bus->resource[2];
        pcibios_resource_to_bus(bridge, &region, res);
        if (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);
                }
                dev_info(&bridge->dev, "  bridge window %pR\n", 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;

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

        if (type & IORESOURCE_IO)
                pci_setup_bridge_io(bus);

        if (type & IORESOURCE_MEM)
                pci_setup_bridge_mmio(bus);

        if (type & IORESOURCE_PREFETCH)
                pci_setup_bridge_mmio_pref(bus);

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

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

        __pci_setup_bridge(bus, type);
}

/* 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)
{
        u16 io;
        u32 pmem;
        struct pci_dev *bridge = bus->self;
        struct resource *b_res;

        b_res = &bridge->resource[PCI_BRIDGE_RESOURCES];
        b_res[1].flags |= IORESOURCE_MEM;

        pci_read_config_word(bridge, PCI_IO_BASE, &io);
        if (!io) {
                pci_write_config_word(bridge, PCI_IO_BASE, 0xf0f0);
                pci_read_config_word(bridge, PCI_IO_BASE, &io);
                pci_write_config_word(bridge, PCI_IO_BASE, 0x0);
        }
        if (io)
                b_res[0].flags |= IORESOURCE_IO;
        /*  DECchip 21050 pass 2 errata: the bridge may miss an address
            disconnect boundary by one PCI data phase.
            Workaround: do not use prefetching on this device. */
        if (bridge->vendor == PCI_VENDOR_ID_DEC && bridge->device == 0x0001)
                return;
        pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem);
        if (!pmem) {
                pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE,
                                               0xfff0fff0);
                pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem);
                pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0);
        }
        if (pmem) {
                b_res[2].flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH;
                if ((pmem & PCI_PREF_RANGE_TYPE_MASK) ==
                    PCI_PREF_RANGE_TYPE_64) {
                        b_res[2].flags |= IORESOURCE_MEM_64;
                        b_res[2].flags |= PCI_PREF_RANGE_TYPE_64;
                }
        }

        /* double check if bridge does support 64 bit pref */
        if (b_res[2].flags & IORESOURCE_MEM_64) {
                u32 mem_base_hi, tmp;
                pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32,
                                         &mem_base_hi);
                pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32,
                                               0xffffffff);
                pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp);
                if (!tmp)
                        b_res[2].flags &= ~IORESOURCE_MEM_64;
                pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32,
                                       mem_base_hi);
        }
}

/* Helper function for sizing routines: find first available
   bus resource of a given type. Note: we intentionally skip
   the bus resources which have already been assigned (that is,
   have non-NULL parent resource). */
static struct resource *find_free_bus_resource(struct pci_bus *bus, unsigned long type)
{
        int i;
        struct resource *r;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
                                  IORESOURCE_PREFETCH;

        pci_bus_for_each_resource(bus, r, i) {
                if (r == &ioport_resource || r == &iomem_resource)
                        continue;
                if (r && (r->flags & type_mask) == type && !r->parent)
                        return r;
        }
        return NULL;
}

static resource_size_t calculate_iosize(resource_size_t size,
                resource_size_t min_size,
                resource_size_t size1,
                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 = ALIGN(size + size1, align);
        if (size < old_size)
                size = old_size;
        return size;
}

static resource_size_t calculate_memsize(resource_size_t size,
                resource_size_t min_size,
                resource_size_t size1,
                resource_size_t old_size,
                resource_size_t align)
{
        if (size < min_size)
                size = min_size;
        if (old_size == 1 )
                old_size = 0;
        if (size < old_size)
                size = old_size;
        size = ALIGN(size + size1, align);
        return size;
}

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

#define PCI_P2P_DEFAULT_MEM_ALIGN       0x100000        /* 1MiB */
#define PCI_P2P_DEFAULT_IO_ALIGN        0x1000          /* 4KiB */
#define PCI_P2P_DEFAULT_IO_ALIGN_1K     0x400           /* 1KiB */

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->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 io window of a given bus
 *
 * @bus : the bus
 * @min_size : the minimum io window that must to be allocated
 * @add_size : additional optional io window
 * @realloc_head : track the additional io window on this list
 *
 * Sizing the IO windows of the PCI-PCI bridge is trivial,
 * since these windows have 1K or 4K granularity and the IO 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 min_size,
                resource_size_t add_size, struct list_head *realloc_head)
{
        struct pci_dev *dev;
        struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO);
        unsigned long size = 0, size0 = 0, size1 = 0;
        resource_size_t children_add_size = 0;
        resource_size_t min_align, io_align, align;

        if (!b_res)
                return;

        io_align = min_align = window_alignment(bus, IORESOURCE_IO);
        list_for_each_entry(dev, &bus->devices, bus_list) {
                int i;

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

                        if (r->parent || !(r->flags & IORESOURCE_IO))
                                continue;
                        r_size = resource_size(r);

                        if (r_size < 0x400)
                                /* 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);
                }
        }

        if (min_align > io_align)
                min_align = io_align;

        size0 = calculate_iosize(size, min_size, size1,
                        resource_size(b_res), min_align);
        if (children_add_size > add_size)
                add_size = children_add_size;
        size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 :
                calculate_iosize(size, min_size, add_size + size1,
                        resource_size(b_res), min_align);
        if (!size0 && !size1) {
                if (b_res->start || b_res->end)
                        dev_info(&bus->self->dev, "disabling bridge window "
                                 "%pR to %pR (unused)\n", b_res,
                                 &bus->busn_res);
                b_res->flags = 0;
                return;
        }

        b_res->start = min_align;
        b_res->end = b_res->start + size0 - 1;
        b_res->flags |= IORESOURCE_STARTALIGN;
        if (size1 > size0 && realloc_head) {
                add_to_list(realloc_head, bus->self, b_res, size1-size0,
                            min_align);
                dev_printk(KERN_DEBUG, &bus->self->dev, "bridge window "
                                 "%pR to %pR add_size %lx\n", b_res,
                                 &bus->busn_res, 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 + 20);

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

        return min_align;
}

/**
 * pbus_size_mem() - size the memory window of a given bus
 *
 * @bus : the bus
 * @min_size : the minimum memory window that must to be allocated
 * @add_size : additional optional memory window
 * @realloc_head : track the additional memory window on this list
 *
 * Calculate the size of the bus and minimal alignment which
 * guarantees that all child resources fit in this size.
 */
static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
                         unsigned long type, resource_size_t min_size,
                        resource_size_t add_size,
                        struct list_head *realloc_head)
{
        struct pci_dev *dev;
        resource_size_t min_align, align, size, size0, size1;
        resource_size_t aligns[12];     /* Alignments from 1Mb to 2Gb */
        int order, max_order;
        struct resource *b_res = find_free_bus_resource(bus, type);
        unsigned int mem64_mask = 0;
        resource_size_t children_add_size = 0;

        if (!b_res)
                return 0;

        memset(aligns, 0, sizeof(aligns));
        max_order = 0;
        size = 0;

        mem64_mask = b_res->flags & IORESOURCE_MEM_64;
        b_res->flags &= ~IORESOURCE_MEM_64;

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

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

                        if (r->parent || (r->flags & mask) != type)
                                continue;
                        r_size = resource_size(r);
#ifdef CONFIG_PCI_IOV
                        /* put SRIOV requested res to the optional list */
                        if (realloc_head && i >= PCI_IOV_RESOURCES &&
                                        i <= PCI_IOV_RESOURCE_END) {
                                r->end = r->start - 1;
                                add_to_list(realloc_head, dev, r, r_size, 0/* dont' care */);
                                children_add_size += r_size;
                                continue;
                        }
#endif
                        /* For bridges size != alignment */
                        align = pci_resource_alignment(dev, r);
                        order = __ffs(align) - 20;
                        if (order > 11) {
                                dev_warn(&dev->dev, "disabling BAR %d: %pR "
                                         "(bad alignment %#llx)\n", i, r,
                                         (unsigned long long) align);
                                r->flags = 0;
                                continue;
                        }
                        size += r_size;
                        if (order < 0)
                                order = 0;
                        /* Exclude ranges with size > align from
                           calculation of the alignment. */
                        if (r_size == align)
                                aligns[order] += align;
                        if (order > max_order)
                                max_order = order;
                        mem64_mask &= r->flags & IORESOURCE_MEM_64;

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

        min_align = calculate_mem_align(aligns, max_order);
        min_align = max(min_align, window_alignment(bus, b_res->flags & mask));
        size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align);
        if (children_add_size > add_size)
                add_size = children_add_size;
        size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 :
                calculate_memsize(size, min_size, add_size,
                                resource_size(b_res), min_align);
        if (!size0 && !size1) {
                if (b_res->start || b_res->end)
                        dev_info(&bus->self->dev, "disabling bridge window "
                                 "%pR to %pR (unused)\n", b_res,
                                 &bus->busn_res);
                b_res->flags = 0;
                return 1;
        }
        b_res->start = min_align;
        b_res->end = size0 + min_align - 1;
        b_res->flags |= IORESOURCE_STARTALIGN | mem64_mask;
        if (size1 > size0 && realloc_head) {
                add_to_list(realloc_head, bus->self, b_res, size1-size0, min_align);
                dev_printk(KERN_DEBUG, &bus->self->dev, "bridge window "
                                 "%pR to %pR add_size %llx\n", b_res,
                                 &bus->busn_res, (unsigned long long)size1-size0);
        }
        return 1;
}

unsigned long pci_cardbus_resource_alignment(struct resource *res)
{
        if (res->flags & IORESOURCE_IO)
                return pci_cardbus_io_size;
        if (res->flags & IORESOURCE_MEM)
                return pci_cardbus_mem_size;
        return 0;
}

static void pci_bus_size_cardbus(struct pci_bus *bus,
                        struct list_head *realloc_head)
{
        struct pci_dev *bridge = bus->self;
        struct resource *b_res = &bridge->resource[PCI_BRIDGE_RESOURCES];
        resource_size_t b_res_3_size = pci_cardbus_mem_size * 2;
        u16 ctrl;

        if (b_res[0].parent)
                goto handle_b_res_1;
        /*
         * Reserve some resources for CardBus.  We reserve
         * a fixed amount of bus space for CardBus bridges.
         */
        b_res[0].start = pci_cardbus_io_size;
        b_res[0].end = b_res[0].start + pci_cardbus_io_size - 1;
        b_res[0].flags |= IORESOURCE_IO | IORESOURCE_STARTALIGN;
        if (realloc_head) {
                b_res[0].end -= pci_cardbus_io_size;
                add_to_list(realloc_head, bridge, b_res, pci_cardbus_io_size,
                                pci_cardbus_io_size);
        }

handle_b_res_1:
        if (b_res[1].parent)
                goto handle_b_res_2;
        b_res[1].start = pci_cardbus_io_size;
        b_res[1].end = b_res[1].start + pci_cardbus_io_size - 1;
        b_res[1].flags |= IORESOURCE_IO | IORESOURCE_STARTALIGN;
        if (realloc_head) {
                b_res[1].end -= pci_cardbus_io_size;
                add_to_list(realloc_head, bridge, b_res+1, pci_cardbus_io_size,
                                 pci_cardbus_io_size);
        }

handle_b_res_2:
        /* MEM1 must not be pref mmio */
        pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
        if (ctrl & PCI_CB_BRIDGE_CTL_PREFETCH_MEM1) {
                ctrl &= ~PCI_CB_BRIDGE_CTL_PREFETCH_MEM1;
                pci_write_config_word(bridge, PCI_CB_BRIDGE_CONTROL, ctrl);
                pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
        }

        /*
         * Check whether prefetchable memory is supported
         * by this bridge.
         */
        pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
        if (!(ctrl & PCI_CB_BRIDGE_CTL_PREFETCH_MEM0)) {
                ctrl |= PCI_CB_BRIDGE_CTL_PREFETCH_MEM0;
                pci_write_config_word(bridge, PCI_CB_BRIDGE_CONTROL, ctrl);
                pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
        }

        if (b_res[2].parent)
                goto handle_b_res_3;
        /*
         * If we have prefetchable memory support, allocate
         * two regions.  Otherwise, allocate one region of
         * twice the size.
         */
        if (ctrl & PCI_CB_BRIDGE_CTL_PREFETCH_MEM0) {
                b_res[2].start = pci_cardbus_mem_size;
                b_res[2].end = b_res[2].start + pci_cardbus_mem_size - 1;
                b_res[2].flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH |
                                  IORESOURCE_STARTALIGN;
                if (realloc_head) {
                        b_res[2].end -= pci_cardbus_mem_size;
                        add_to_list(realloc_head, bridge, b_res+2,
                                 pci_cardbus_mem_size, pci_cardbus_mem_size);
                }

                /* reduce that to half */
                b_res_3_size = pci_cardbus_mem_size;
        }

handle_b_res_3:
        if (b_res[3].parent)
                goto handle_done;
        b_res[3].start = pci_cardbus_mem_size;
        b_res[3].end = b_res[3].start + b_res_3_size - 1;
        b_res[3].flags |= IORESOURCE_MEM | IORESOURCE_STARTALIGN;
        if (realloc_head) {
                b_res[3].end -= b_res_3_size;
                add_to_list(realloc_head, bridge, b_res+3, b_res_3_size,
                                 pci_cardbus_mem_size);
        }

handle_done:
        ;
}

void __ref __pci_bus_size_bridges(struct pci_bus *bus,
                        struct list_head *realloc_head)
{
        struct pci_dev *dev;
        unsigned long mask, prefmask;
        resource_size_t additional_mem_size = 0, additional_io_size = 0;

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

                switch (dev->class >> 8) {
                case PCI_CLASS_BRIDGE_CARDBUS:
                        pci_bus_size_cardbus(b, realloc_head);
                        break;

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

        /* The root bus? */
        if (!bus->self)
                return;

        switch (bus->self->class >> 8) {
        case PCI_CLASS_BRIDGE_CARDBUS:
                /* don't size cardbuses yet. */
                break;

        case PCI_CLASS_BRIDGE_PCI:
                pci_bridge_check_ranges(bus);
                if (bus->self->is_hotplug_bridge) {
                        additional_io_size  = pci_hotplug_io_size;
                        additional_mem_size = pci_hotplug_mem_size;
                }
                /*
                 * Follow thru
                 */
        default:
                pbus_size_io(bus, realloc_head ? 0 : additional_io_size,
                             additional_io_size, realloc_head);
                /* If the bridge supports prefetchable range, size it
                   separately. If it doesn't, or its prefetchable window
                   has already been allocated by arch code, try
                   non-prefetchable range for both types of PCI memory
                   resources. */
                mask = IORESOURCE_MEM;
                prefmask = IORESOURCE_MEM | IORESOURCE_PREFETCH;
                if (pbus_size_mem(bus, prefmask, prefmask,
                                  realloc_head ? 0 : additional_mem_size,
                                  additional_mem_size, realloc_head))
                        mask = prefmask; /* Success, size non-prefetch only. */
                else
                        additional_mem_size += additional_mem_size;
                pbus_size_mem(bus, mask, IORESOURCE_MEM,
                                realloc_head ? 0 : additional_mem_size,
                                additional_mem_size, realloc_head);
                break;
        }
}

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

void __ref __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) {
                b = dev->subordinate;
                if (!b)
                        continue;

                __pci_bus_assign_resources(b, realloc_head, fail_head);

                switch (dev->class >> 8) {
                case PCI_CLASS_BRIDGE_PCI:
                        if (!pci_is_enabled(dev))
                                pci_setup_bridge(b);
                        break;

                case PCI_CLASS_BRIDGE_CARDBUS:
                        pci_setup_cardbus(b);
                        break;

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

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

static void __ref __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(b);
                break;

        default:
                dev_info(&bridge->dev, "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,
                                          unsigned long type)
{
        int idx;
        bool changed = false;
        struct pci_dev *dev;
        struct resource *r;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
                                  IORESOURCE_PREFETCH;

        dev = bus->self;
        for (idx = PCI_BRIDGE_RESOURCES; idx <= PCI_BRIDGE_RESOURCE_END;
             idx++) {
                r = &dev->resource[idx];
                if ((r->flags & type_mask) != type)
                        continue;
                if (!r->parent)
                        continue;
                /*
                 * if there are children under that, we should release them
                 *  all
                 */
                release_child_resources(r);
                if (!release_resource(r)) {
                        dev_printk(KERN_DEBUG, &dev->dev,
                                 "resource %d %pR released\n", idx, r);
                        /* keep the old size */
                        r->end = resource_size(r) - 1;
                        r->start = 0;
                        r->flags = 0;
                        changed = true;
                }
        }

        if (changed) {
                /* avoiding touch the one without PREF */
                if (type & IORESOURCE_PREFETCH)
                        type = IORESOURCE_PREFETCH;
                __pci_setup_bridge(bus, type);
        }
}

enum release_type {
        leaf_only,
        whole_subtree,
};
/*
 * try to release pci bridge resources that is from leaf bridge,
 * so we can allocate big new one later
 */
static void __ref pci_bus_release_bridge_resources(struct pci_bus *bus,
                                                   unsigned long type,
                                                   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;
                if (!b)
                        continue;

                is_leaf_bridge = false;

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

                if (rel_type == whole_subtree)
                        pci_bus_release_bridge_resources(b, type,
                                                 whole_subtree);
        }

        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, type);
}

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_printk(KERN_DEBUG, &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 __init pci_bus_get_depth(struct pci_bus *bus)
{
        int depth = 0;
        struct pci_dev *dev;

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

                ret = pci_bus_get_depth(b);
                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 __initdata = 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 __init pci_realloc_enabled(enum enable_type enable)
{
        return enable >= user_enabled;
}

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

        for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
                struct resource *r = &dev->resource[i];
                struct pci_bus_region region;

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

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

        return 0;
}

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

        if (enable_local != undefined)
                return enable_local;

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

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

/*
 * first try will not touch pci bridge res
 * second  and later try will clear small leaf bridge res
 * will stop till to the max  deepth if can not find good one
 */
static void __init
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);
        struct pci_dev_resource *fail_res;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
                                  IORESOURCE_PREFETCH;
        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_printk(KERN_DEBUG, &bus->dev,
                           "max bus depth: %d pci_try_num: %d\n",
                           max_depth, pci_try_num);
        }

again:
        /*
         * 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);

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

        /* any device complain? */
        if (list_empty(&fail_head))
                goto dump;

        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");

                free_list(&fail_head);
                goto dump;
        }

        dev_printk(KERN_DEBUG, &bus->dev,
                   "No. %d try to assign unassigned res\n", tried_times + 1);

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

        /*
         * Try to release leaf bridge's resources that doesn't fit resource of
         * child device under that bridge
         */
        list_for_each_entry(fail_res, &fail_head, list)
                pci_bus_release_bridge_resources(fail_res->dev->bus,
                                                 fail_res->flags & type_mask,
                                                 rel_type);

        /* restore size and flags */
        list_for_each_entry(fail_res, &fail_head, list) {
                struct resource *res = fail_res->res;

                res->start = fail_res->start;
                res->end = fail_res->end;
                res->flags = fail_res->flags;
                if (fail_res->dev->subordinate)
                        res->flags = 0;
        }
        free_list(&fail_head);

        goto again;

dump:
        /* dump the resource on buses */
        pci_bus_dump_resources(bus);
}

void __init 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);
}

void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
{
        struct pci_bus *parent = bridge->subordinate;
        LIST_HEAD(add_list); /* list of resources that
                                        want additional resources */
        int tried_times = 0;
        LIST_HEAD(fail_head);
        struct pci_dev_resource *fail_res;
        int retval;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
                                  IORESOURCE_PREFETCH;

again:
        __pci_bus_size_bridges(parent, &add_list);
        __pci_bridge_assign_resources(bridge, &add_list, &fail_head);
        BUG_ON(!list_empty(&add_list));
        tried_times++;

        if (list_empty(&fail_head))
                goto enable_all;

        if (tried_times >= 2) {
                /* still fail, don't need to try more */
                free_list(&fail_head);
                goto enable_all;
        }

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

        /*
         * Try to release leaf bridge's resources that doesn't fit resource of
         * child device under that bridge
         */
        list_for_each_entry(fail_res, &fail_head, list)
                pci_bus_release_bridge_resources(fail_res->dev->bus,
                                                 fail_res->flags & type_mask,
                                                 whole_subtree);

        /* restore size and flags */
        list_for_each_entry(fail_res, &fail_head, list) {
                struct resource *res = fail_res->res;

                res->start = fail_res->start;
                res->end = fail_res->end;
                res->flags = fail_res->flags;
                if (fail_res->dev->subordinate)
                        res->flags = 0;
        }
        free_list(&fail_head);

        goto again;

enable_all:
        retval = pci_reenable_device(bridge);
        if (retval)
                dev_err(&bridge->dev, "Error reenabling bridge (%d)\n", retval);
        pci_set_master(bridge);
}
EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);

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

        down_read(&pci_bus_sem);
        list_for_each_entry(dev, &bus->devices, bus_list)
                if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
                    dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
                        if (dev->subordinate)
                                __pci_bus_size_bridges(dev->subordinate,
                                                         &add_list);
        up_read(&pci_bus_sem);
        __pci_bus_assign_resources(bus, &add_list, NULL);
        BUG_ON(!list_empty(&add_list));
}