drm/amd/display: Add bypass case for PQ transfer function

[mirror_ubuntu-bionic-kernel.git] / drivers / pci / probe.c

/*
 * probe.c - PCI detection and setup code
 */

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/of_device.h>
#include <linux/of_pci.h>
#include <linux/pci_hotplug.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/pci-aspm.h>
#include <linux/aer.h>
#include <linux/acpi.h>
#include <linux/irqdomain.h>
#include <linux/pm_runtime.h>
#include "pci.h"

#define CARDBUS_LATENCY_TIMER   176     /* secondary latency timer */
#define CARDBUS_RESERVE_BUSNR   3

static struct resource busn_resource = {
        .name   = "PCI busn",
        .start  = 0,
        .end    = 255,
        .flags  = IORESOURCE_BUS,
};

/* Ugh.  Need to stop exporting this to modules. */
LIST_HEAD(pci_root_buses);
EXPORT_SYMBOL(pci_root_buses);

static LIST_HEAD(pci_domain_busn_res_list);

struct pci_domain_busn_res {
        struct list_head list;
        struct resource res;
        int domain_nr;
};

static struct resource *get_pci_domain_busn_res(int domain_nr)
{
        struct pci_domain_busn_res *r;

        list_for_each_entry(r, &pci_domain_busn_res_list, list)
                if (r->domain_nr == domain_nr)
                        return &r->res;

        r = kzalloc(sizeof(*r), GFP_KERNEL);
        if (!r)
                return NULL;

        r->domain_nr = domain_nr;
        r->res.start = 0;
        r->res.end = 0xff;
        r->res.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED;

        list_add_tail(&r->list, &pci_domain_busn_res_list);

        return &r->res;
}

static int find_anything(struct device *dev, void *data)
{
        return 1;
}

/*
 * Some device drivers need know if pci is initiated.
 * Basically, we think pci is not initiated when there
 * is no device to be found on the pci_bus_type.
 */
int no_pci_devices(void)
{
        struct device *dev;
        int no_devices;

        dev = bus_find_device(&pci_bus_type, NULL, NULL, find_anything);
        no_devices = (dev == NULL);
        put_device(dev);
        return no_devices;
}
EXPORT_SYMBOL(no_pci_devices);

/*
 * PCI Bus Class
 */
static void release_pcibus_dev(struct device *dev)
{
        struct pci_bus *pci_bus = to_pci_bus(dev);

        put_device(pci_bus->bridge);
        pci_bus_remove_resources(pci_bus);
        pci_release_bus_of_node(pci_bus);
        kfree(pci_bus);
}

static struct class pcibus_class = {
        .name           = "pci_bus",
        .dev_release    = &release_pcibus_dev,
        .dev_groups     = pcibus_groups,
};

static int __init pcibus_class_init(void)
{
        return class_register(&pcibus_class);
}
postcore_initcall(pcibus_class_init);

static u64 pci_size(u64 base, u64 maxbase, u64 mask)
{
        u64 size = mask & maxbase;      /* Find the significant bits */
        if (!size)
                return 0;

        /* Get the lowest of them to find the decode size, and
           from that the extent.  */
        size = (size & ~(size-1)) - 1;

        /* base == maxbase can be valid only if the BAR has
           already been programmed with all 1s.  */
        if (base == maxbase && ((base | size) & mask) != mask)
                return 0;

        return size;
}

static inline unsigned long decode_bar(struct pci_dev *dev, u32 bar)
{
        u32 mem_type;
        unsigned long flags;

        if ((bar & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
                flags = bar & ~PCI_BASE_ADDRESS_IO_MASK;
                flags |= IORESOURCE_IO;
                return flags;
        }

        flags = bar & ~PCI_BASE_ADDRESS_MEM_MASK;
        flags |= IORESOURCE_MEM;
        if (flags & PCI_BASE_ADDRESS_MEM_PREFETCH)
                flags |= IORESOURCE_PREFETCH;

        mem_type = bar & PCI_BASE_ADDRESS_MEM_TYPE_MASK;
        switch (mem_type) {
        case PCI_BASE_ADDRESS_MEM_TYPE_32:
                break;
        case PCI_BASE_ADDRESS_MEM_TYPE_1M:
                /* 1M mem BAR treated as 32-bit BAR */
                break;
        case PCI_BASE_ADDRESS_MEM_TYPE_64:
                flags |= IORESOURCE_MEM_64;
                break;
        default:
                /* mem unknown type treated as 32-bit BAR */
                break;
        }
        return flags;
}

#define PCI_COMMAND_DECODE_ENABLE       (PCI_COMMAND_MEMORY | PCI_COMMAND_IO)

/**
 * pci_read_base - read a PCI BAR
 * @dev: the PCI device
 * @type: type of the BAR
 * @res: resource buffer to be filled in
 * @pos: BAR position in the config space
 *
 * Returns 1 if the BAR is 64-bit, or 0 if 32-bit.
 */
int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
                    struct resource *res, unsigned int pos)
{
        u32 l = 0, sz = 0, mask;
        u64 l64, sz64, mask64;
        u16 orig_cmd;
        struct pci_bus_region region, inverted_region;

        mask = type ? PCI_ROM_ADDRESS_MASK : ~0;

        /* No printks while decoding is disabled! */
        if (!dev->mmio_always_on) {
                pci_read_config_word(dev, PCI_COMMAND, &orig_cmd);
                if (orig_cmd & PCI_COMMAND_DECODE_ENABLE) {
                        pci_write_config_word(dev, PCI_COMMAND,
                                orig_cmd & ~PCI_COMMAND_DECODE_ENABLE);
                }
        }

        res->name = pci_name(dev);

        pci_read_config_dword(dev, pos, &l);
        pci_write_config_dword(dev, pos, l | mask);
        pci_read_config_dword(dev, pos, &sz);
        pci_write_config_dword(dev, pos, l);

        /*
         * All bits set in sz means the device isn't working properly.
         * If the BAR isn't implemented, all bits must be 0.  If it's a
         * memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
         * 1 must be clear.
         */
        if (sz == 0xffffffff)
                sz = 0;

        /*
         * I don't know how l can have all bits set.  Copied from old code.
         * Maybe it fixes a bug on some ancient platform.
         */
        if (l == 0xffffffff)
                l = 0;

        if (type == pci_bar_unknown) {
                res->flags = decode_bar(dev, l);
                res->flags |= IORESOURCE_SIZEALIGN;
                if (res->flags & IORESOURCE_IO) {
                        l64 = l & PCI_BASE_ADDRESS_IO_MASK;
                        sz64 = sz & PCI_BASE_ADDRESS_IO_MASK;
                        mask64 = PCI_BASE_ADDRESS_IO_MASK & (u32)IO_SPACE_LIMIT;
                } else {
                        l64 = l & PCI_BASE_ADDRESS_MEM_MASK;
                        sz64 = sz & PCI_BASE_ADDRESS_MEM_MASK;
                        mask64 = (u32)PCI_BASE_ADDRESS_MEM_MASK;
                }
        } else {
                if (l & PCI_ROM_ADDRESS_ENABLE)
                        res->flags |= IORESOURCE_ROM_ENABLE;
                l64 = l & PCI_ROM_ADDRESS_MASK;
                sz64 = sz & PCI_ROM_ADDRESS_MASK;
                mask64 = PCI_ROM_ADDRESS_MASK;
        }

        if (res->flags & IORESOURCE_MEM_64) {
                pci_read_config_dword(dev, pos + 4, &l);
                pci_write_config_dword(dev, pos + 4, ~0);
                pci_read_config_dword(dev, pos + 4, &sz);
                pci_write_config_dword(dev, pos + 4, l);

                l64 |= ((u64)l << 32);
                sz64 |= ((u64)sz << 32);
                mask64 |= ((u64)~0 << 32);
        }

        if (!dev->mmio_always_on && (orig_cmd & PCI_COMMAND_DECODE_ENABLE))
                pci_write_config_word(dev, PCI_COMMAND, orig_cmd);

        if (!sz64)
                goto fail;

        sz64 = pci_size(l64, sz64, mask64);
        if (!sz64) {
                dev_info(&dev->dev, FW_BUG "reg 0x%x: invalid BAR (can't size)\n",
                         pos);
                goto fail;
        }

        if (res->flags & IORESOURCE_MEM_64) {
                if ((sizeof(pci_bus_addr_t) < 8 || sizeof(resource_size_t) < 8)
                    && sz64 > 0x100000000ULL) {
                        res->flags |= IORESOURCE_UNSET | IORESOURCE_DISABLED;
                        res->start = 0;
                        res->end = 0;
                        dev_err(&dev->dev, "reg 0x%x: can't handle BAR larger than 4GB (size %#010llx)\n",
                                pos, (unsigned long long)sz64);
                        goto out;
                }

                if ((sizeof(pci_bus_addr_t) < 8) && l) {
                        /* Above 32-bit boundary; try to reallocate */
                        res->flags |= IORESOURCE_UNSET;
                        res->start = 0;
                        res->end = sz64;
                        dev_info(&dev->dev, "reg 0x%x: can't handle BAR above 4GB (bus address %#010llx)\n",
                                 pos, (unsigned long long)l64);
                        goto out;
                }
        }

        region.start = l64;
        region.end = l64 + sz64;

        pcibios_bus_to_resource(dev->bus, res, &region);
        pcibios_resource_to_bus(dev->bus, &inverted_region, res);

        /*
         * If "A" is a BAR value (a bus address), "bus_to_resource(A)" is
         * the corresponding resource address (the physical address used by
         * the CPU.  Converting that resource address back to a bus address
         * should yield the original BAR value:
         *
         *     resource_to_bus(bus_to_resource(A)) == A
         *
         * If it doesn't, CPU accesses to "bus_to_resource(A)" will not
         * be claimed by the device.
         */
        if (inverted_region.start != region.start) {
                res->flags |= IORESOURCE_UNSET;
                res->start = 0;
                res->end = region.end - region.start;
                dev_info(&dev->dev, "reg 0x%x: initial BAR value %#010llx invalid\n",
                         pos, (unsigned long long)region.start);
        }

        goto out;


fail:
        res->flags = 0;
out:
        if (res->flags)
                dev_printk(KERN_DEBUG, &dev->dev, "reg 0x%x: %pR\n", pos, res);

        return (res->flags & IORESOURCE_MEM_64) ? 1 : 0;
}

static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
{
        unsigned int pos, reg;

        if (dev->non_compliant_bars)
                return;

        for (pos = 0; pos < howmany; pos++) {
                struct resource *res = &dev->resource[pos];
                reg = PCI_BASE_ADDRESS_0 + (pos << 2);
                pos += __pci_read_base(dev, pci_bar_unknown, res, reg);
        }

        if (rom) {
                struct resource *res = &dev->resource[PCI_ROM_RESOURCE];
                dev->rom_base_reg = rom;
                res->flags = IORESOURCE_MEM | IORESOURCE_PREFETCH |
                                IORESOURCE_READONLY | IORESOURCE_SIZEALIGN;
                __pci_read_base(dev, pci_bar_mem32, res, rom);
        }
}

static void pci_read_bridge_io(struct pci_bus *child)
{
        struct pci_dev *dev = child->self;
        u8 io_base_lo, io_limit_lo;
        unsigned long io_mask, io_granularity, base, limit;
        struct pci_bus_region region;
        struct resource *res;

        io_mask = PCI_IO_RANGE_MASK;
        io_granularity = 0x1000;
        if (dev->io_window_1k) {
                /* Support 1K I/O space granularity */
                io_mask = PCI_IO_1K_RANGE_MASK;
                io_granularity = 0x400;
        }

        res = child->resource[0];
        pci_read_config_byte(dev, PCI_IO_BASE, &io_base_lo);
        pci_read_config_byte(dev, PCI_IO_LIMIT, &io_limit_lo);
        base = (io_base_lo & io_mask) << 8;
        limit = (io_limit_lo & io_mask) << 8;

        if ((io_base_lo & PCI_IO_RANGE_TYPE_MASK) == PCI_IO_RANGE_TYPE_32) {
                u16 io_base_hi, io_limit_hi;

                pci_read_config_word(dev, PCI_IO_BASE_UPPER16, &io_base_hi);
                pci_read_config_word(dev, PCI_IO_LIMIT_UPPER16, &io_limit_hi);
                base |= ((unsigned long) io_base_hi << 16);
                limit |= ((unsigned long) io_limit_hi << 16);
        }

        if (base <= limit) {
                res->flags = (io_base_lo & PCI_IO_RANGE_TYPE_MASK) | IORESOURCE_IO;
                region.start = base;
                region.end = limit + io_granularity - 1;
                pcibios_bus_to_resource(dev->bus, res, &region);
                dev_printk(KERN_DEBUG, &dev->dev, "  bridge window %pR\n", res);
        }
}

static void pci_read_bridge_mmio(struct pci_bus *child)
{
        struct pci_dev *dev = child->self;
        u16 mem_base_lo, mem_limit_lo;
        unsigned long base, limit;
        struct pci_bus_region region;
        struct resource *res;

        res = child->resource[1];
        pci_read_config_word(dev, PCI_MEMORY_BASE, &mem_base_lo);
        pci_read_config_word(dev, PCI_MEMORY_LIMIT, &mem_limit_lo);
        base = ((unsigned long) mem_base_lo & PCI_MEMORY_RANGE_MASK) << 16;
        limit = ((unsigned long) mem_limit_lo & PCI_MEMORY_RANGE_MASK) << 16;
        if (base <= limit) {
                res->flags = (mem_base_lo & PCI_MEMORY_RANGE_TYPE_MASK) | IORESOURCE_MEM;
                region.start = base;
                region.end = limit + 0xfffff;
                pcibios_bus_to_resource(dev->bus, res, &region);
                dev_printk(KERN_DEBUG, &dev->dev, "  bridge window %pR\n", res);
        }
}

static void pci_read_bridge_mmio_pref(struct pci_bus *child)
{
        struct pci_dev *dev = child->self;
        u16 mem_base_lo, mem_limit_lo;
        u64 base64, limit64;
        pci_bus_addr_t base, limit;
        struct pci_bus_region region;
        struct resource *res;

        res = child->resource[2];
        pci_read_config_word(dev, PCI_PREF_MEMORY_BASE, &mem_base_lo);
        pci_read_config_word(dev, PCI_PREF_MEMORY_LIMIT, &mem_limit_lo);
        base64 = (mem_base_lo & PCI_PREF_RANGE_MASK) << 16;
        limit64 = (mem_limit_lo & PCI_PREF_RANGE_MASK) << 16;

        if ((mem_base_lo & PCI_PREF_RANGE_TYPE_MASK) == PCI_PREF_RANGE_TYPE_64) {
                u32 mem_base_hi, mem_limit_hi;

                pci_read_config_dword(dev, PCI_PREF_BASE_UPPER32, &mem_base_hi);
                pci_read_config_dword(dev, PCI_PREF_LIMIT_UPPER32, &mem_limit_hi);

                /*
                 * Some bridges set the base > limit by default, and some
                 * (broken) BIOSes do not initialize them.  If we find
                 * this, just assume they are not being used.
                 */
                if (mem_base_hi <= mem_limit_hi) {
                        base64 |= (u64) mem_base_hi << 32;
                        limit64 |= (u64) mem_limit_hi << 32;
                }
        }

        base = (pci_bus_addr_t) base64;
        limit = (pci_bus_addr_t) limit64;

        if (base != base64) {
                dev_err(&dev->dev, "can't handle bridge window above 4GB (bus address %#010llx)\n",
                        (unsigned long long) base64);
                return;
        }

        if (base <= limit) {
                res->flags = (mem_base_lo & PCI_PREF_RANGE_TYPE_MASK) |
                                         IORESOURCE_MEM | IORESOURCE_PREFETCH;
                if (res->flags & PCI_PREF_RANGE_TYPE_64)
                        res->flags |= IORESOURCE_MEM_64;
                region.start = base;
                region.end = limit + 0xfffff;
                pcibios_bus_to_resource(dev->bus, res, &region);
                dev_printk(KERN_DEBUG, &dev->dev, "  bridge window %pR\n", res);
        }
}

void pci_read_bridge_bases(struct pci_bus *child)
{
        struct pci_dev *dev = child->self;
        struct resource *res;
        int i;

        if (pci_is_root_bus(child))     /* It's a host bus, nothing to read */
                return;

        dev_info(&dev->dev, "PCI bridge to %pR%s\n",
                 &child->busn_res,
                 dev->transparent ? " (subtractive decode)" : "");

        pci_bus_remove_resources(child);
        for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
                child->resource[i] = &dev->resource[PCI_BRIDGE_RESOURCES+i];

        pci_read_bridge_io(child);
        pci_read_bridge_mmio(child);
        pci_read_bridge_mmio_pref(child);

        if (dev->transparent) {
                pci_bus_for_each_resource(child->parent, res, i) {
                        if (res && res->flags) {
                                pci_bus_add_resource(child, res,
                                                     PCI_SUBTRACTIVE_DECODE);
                                dev_printk(KERN_DEBUG, &dev->dev,
                                           "  bridge window %pR (subtractive decode)\n",
                                           res);
                        }
                }
        }
}

static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
{
        struct pci_bus *b;

        b = kzalloc(sizeof(*b), GFP_KERNEL);
        if (!b)
                return NULL;

        INIT_LIST_HEAD(&b->node);
        INIT_LIST_HEAD(&b->children);
        INIT_LIST_HEAD(&b->devices);
        INIT_LIST_HEAD(&b->slots);
        INIT_LIST_HEAD(&b->resources);
        b->max_bus_speed = PCI_SPEED_UNKNOWN;
        b->cur_bus_speed = PCI_SPEED_UNKNOWN;
#ifdef CONFIG_PCI_DOMAINS_GENERIC
        if (parent)
                b->domain_nr = parent->domain_nr;
#endif
        return b;
}

static void devm_pci_release_host_bridge_dev(struct device *dev)
{
        struct pci_host_bridge *bridge = to_pci_host_bridge(dev);

        if (bridge->release_fn)
                bridge->release_fn(bridge);
}

static void pci_release_host_bridge_dev(struct device *dev)
{
        devm_pci_release_host_bridge_dev(dev);
        pci_free_host_bridge(to_pci_host_bridge(dev));
}

struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
{
        struct pci_host_bridge *bridge;

        bridge = kzalloc(sizeof(*bridge) + priv, GFP_KERNEL);
        if (!bridge)
                return NULL;

        INIT_LIST_HEAD(&bridge->windows);
        bridge->dev.release = pci_release_host_bridge_dev;

        return bridge;
}
EXPORT_SYMBOL(pci_alloc_host_bridge);

struct pci_host_bridge *devm_pci_alloc_host_bridge(struct device *dev,
                                                   size_t priv)
{
        struct pci_host_bridge *bridge;

        bridge = devm_kzalloc(dev, sizeof(*bridge) + priv, GFP_KERNEL);
        if (!bridge)
                return NULL;

        INIT_LIST_HEAD(&bridge->windows);
        bridge->dev.release = devm_pci_release_host_bridge_dev;

        return bridge;
}
EXPORT_SYMBOL(devm_pci_alloc_host_bridge);

void pci_free_host_bridge(struct pci_host_bridge *bridge)
{
        pci_free_resource_list(&bridge->windows);

        kfree(bridge);
}
EXPORT_SYMBOL(pci_free_host_bridge);

static const unsigned char pcix_bus_speed[] = {
        PCI_SPEED_UNKNOWN,              /* 0 */
        PCI_SPEED_66MHz_PCIX,           /* 1 */
        PCI_SPEED_100MHz_PCIX,          /* 2 */
        PCI_SPEED_133MHz_PCIX,          /* 3 */
        PCI_SPEED_UNKNOWN,              /* 4 */
        PCI_SPEED_66MHz_PCIX_ECC,       /* 5 */
        PCI_SPEED_100MHz_PCIX_ECC,      /* 6 */
        PCI_SPEED_133MHz_PCIX_ECC,      /* 7 */
        PCI_SPEED_UNKNOWN,              /* 8 */
        PCI_SPEED_66MHz_PCIX_266,       /* 9 */
        PCI_SPEED_100MHz_PCIX_266,      /* A */
        PCI_SPEED_133MHz_PCIX_266,      /* B */
        PCI_SPEED_UNKNOWN,              /* C */
        PCI_SPEED_66MHz_PCIX_533,       /* D */
        PCI_SPEED_100MHz_PCIX_533,      /* E */
        PCI_SPEED_133MHz_PCIX_533       /* F */
};

const unsigned char pcie_link_speed[] = {
        PCI_SPEED_UNKNOWN,              /* 0 */
        PCIE_SPEED_2_5GT,               /* 1 */
        PCIE_SPEED_5_0GT,               /* 2 */
        PCIE_SPEED_8_0GT,               /* 3 */
        PCI_SPEED_UNKNOWN,              /* 4 */
        PCI_SPEED_UNKNOWN,              /* 5 */
        PCI_SPEED_UNKNOWN,              /* 6 */
        PCI_SPEED_UNKNOWN,              /* 7 */
        PCI_SPEED_UNKNOWN,              /* 8 */
        PCI_SPEED_UNKNOWN,              /* 9 */
        PCI_SPEED_UNKNOWN,              /* A */
        PCI_SPEED_UNKNOWN,              /* B */
        PCI_SPEED_UNKNOWN,              /* C */
        PCI_SPEED_UNKNOWN,              /* D */
        PCI_SPEED_UNKNOWN,              /* E */
        PCI_SPEED_UNKNOWN               /* F */
};

void pcie_update_link_speed(struct pci_bus *bus, u16 linksta)
{
        bus->cur_bus_speed = pcie_link_speed[linksta & PCI_EXP_LNKSTA_CLS];
}
EXPORT_SYMBOL_GPL(pcie_update_link_speed);

static unsigned char agp_speeds[] = {
        AGP_UNKNOWN,
        AGP_1X,
        AGP_2X,
        AGP_4X,
        AGP_8X
};

static enum pci_bus_speed agp_speed(int agp3, int agpstat)
{
        int index = 0;

        if (agpstat & 4)
                index = 3;
        else if (agpstat & 2)
                index = 2;
        else if (agpstat & 1)
                index = 1;
        else
                goto out;

        if (agp3) {
                index += 2;
                if (index == 5)
                        index = 0;
        }

 out:
        return agp_speeds[index];
}

static void pci_set_bus_speed(struct pci_bus *bus)
{
        struct pci_dev *bridge = bus->self;
        int pos;

        pos = pci_find_capability(bridge, PCI_CAP_ID_AGP);
        if (!pos)
                pos = pci_find_capability(bridge, PCI_CAP_ID_AGP3);
        if (pos) {
                u32 agpstat, agpcmd;

                pci_read_config_dword(bridge, pos + PCI_AGP_STATUS, &agpstat);
                bus->max_bus_speed = agp_speed(agpstat & 8, agpstat & 7);

                pci_read_config_dword(bridge, pos + PCI_AGP_COMMAND, &agpcmd);
                bus->cur_bus_speed = agp_speed(agpstat & 8, agpcmd & 7);
        }

        pos = pci_find_capability(bridge, PCI_CAP_ID_PCIX);
        if (pos) {
                u16 status;
                enum pci_bus_speed max;

                pci_read_config_word(bridge, pos + PCI_X_BRIDGE_SSTATUS,
                                     &status);

                if (status & PCI_X_SSTATUS_533MHZ) {
                        max = PCI_SPEED_133MHz_PCIX_533;
                } else if (status & PCI_X_SSTATUS_266MHZ) {
                        max = PCI_SPEED_133MHz_PCIX_266;
                } else if (status & PCI_X_SSTATUS_133MHZ) {
                        if ((status & PCI_X_SSTATUS_VERS) == PCI_X_SSTATUS_V2)
                                max = PCI_SPEED_133MHz_PCIX_ECC;
                        else
                                max = PCI_SPEED_133MHz_PCIX;
                } else {
                        max = PCI_SPEED_66MHz_PCIX;
                }

                bus->max_bus_speed = max;
                bus->cur_bus_speed = pcix_bus_speed[
                        (status & PCI_X_SSTATUS_FREQ) >> 6];

                return;
        }

        if (pci_is_pcie(bridge)) {
                u32 linkcap;
                u16 linksta;

                pcie_capability_read_dword(bridge, PCI_EXP_LNKCAP, &linkcap);
                bus->max_bus_speed = pcie_link_speed[linkcap & PCI_EXP_LNKCAP_SLS];

                pcie_capability_read_word(bridge, PCI_EXP_LNKSTA, &linksta);
                pcie_update_link_speed(bus, linksta);
        }
}

static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
{
        struct irq_domain *d;

        /*
         * Any firmware interface that can resolve the msi_domain
         * should be called from here.
         */
        d = pci_host_bridge_of_msi_domain(bus);
        if (!d)
                d = pci_host_bridge_acpi_msi_domain(bus);

#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
        /*
         * If no IRQ domain was found via the OF tree, try looking it up
         * directly through the fwnode_handle.
         */
        if (!d) {
                struct fwnode_handle *fwnode = pci_root_bus_fwnode(bus);

                if (fwnode)
                        d = irq_find_matching_fwnode(fwnode,
                                                     DOMAIN_BUS_PCI_MSI);
        }
#endif

        return d;
}

static void pci_set_bus_msi_domain(struct pci_bus *bus)
{
        struct irq_domain *d;
        struct pci_bus *b;

        /*
         * The bus can be a root bus, a subordinate bus, or a virtual bus
         * created by an SR-IOV device.  Walk up to the first bridge device
         * found or derive the domain from the host bridge.
         */
        for (b = bus, d = NULL; !d && !pci_is_root_bus(b); b = b->parent) {
                if (b->self)
                        d = dev_get_msi_domain(&b->self->dev);
        }

        if (!d)
                d = pci_host_bridge_msi_domain(b);

        dev_set_msi_domain(&bus->dev, d);
}

static int pci_register_host_bridge(struct pci_host_bridge *bridge)
{
        struct device *parent = bridge->dev.parent;
        struct resource_entry *window, *n;
        struct pci_bus *bus, *b;
        resource_size_t offset;
        LIST_HEAD(resources);
        struct resource *res;
        char addr[64], *fmt;
        const char *name;
        int err;

        bus = pci_alloc_bus(NULL);
        if (!bus)
                return -ENOMEM;

        bridge->bus = bus;

        /* temporarily move resources off the list */
        list_splice_init(&bridge->windows, &resources);
        bus->sysdata = bridge->sysdata;
        bus->msi = bridge->msi;
        bus->ops = bridge->ops;
        bus->number = bus->busn_res.start = bridge->busnr;
#ifdef CONFIG_PCI_DOMAINS_GENERIC
        bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
#endif

        b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);
        if (b) {
                /* If we already got to this bus through a different bridge, ignore it */
                dev_dbg(&b->dev, "bus already known\n");
                err = -EEXIST;
                goto free;
        }

        dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(bus),
                     bridge->busnr);

        err = pcibios_root_bridge_prepare(bridge);
        if (err)
                goto free;

        err = device_register(&bridge->dev);
        if (err)
                put_device(&bridge->dev);

        bus->bridge = get_device(&bridge->dev);
        device_enable_async_suspend(bus->bridge);
        pci_set_bus_of_node(bus);
        pci_set_bus_msi_domain(bus);

        if (!parent)
                set_dev_node(bus->bridge, pcibus_to_node(bus));

        bus->dev.class = &pcibus_class;
        bus->dev.parent = bus->bridge;

        dev_set_name(&bus->dev, "%04x:%02x", pci_domain_nr(bus), bus->number);
        name = dev_name(&bus->dev);

        err = device_register(&bus->dev);
        if (err)
                goto unregister;

        pcibios_add_bus(bus);

        /* Create legacy_io and legacy_mem files for this bus */
        pci_create_legacy_files(bus);

        if (parent)
                dev_info(parent, "PCI host bridge to bus %s\n", name);
        else
                pr_info("PCI host bridge to bus %s\n", name);

        /* Add initial resources to the bus */
        resource_list_for_each_entry_safe(window, n, &resources) {
                list_move_tail(&window->node, &bridge->windows);
                offset = window->offset;
                res = window->res;

                if (res->flags & IORESOURCE_BUS)
                        pci_bus_insert_busn_res(bus, bus->number, res->end);
                else
                        pci_bus_add_resource(bus, res, 0);

                if (offset) {
                        if (resource_type(res) == IORESOURCE_IO)
                                fmt = " (bus address [%#06llx-%#06llx])";
                        else
                                fmt = " (bus address [%#010llx-%#010llx])";

                        snprintf(addr, sizeof(addr), fmt,
                                 (unsigned long long)(res->start - offset),
                                 (unsigned long long)(res->end - offset));
                } else
                        addr[0] = '\0';

                dev_info(&bus->dev, "root bus resource %pR%s\n", res, addr);
        }

        down_write(&pci_bus_sem);
        list_add_tail(&bus->node, &pci_root_buses);
        up_write(&pci_bus_sem);

        return 0;

unregister:
        put_device(&bridge->dev);
        device_unregister(&bridge->dev);

free:
        kfree(bus);
        return err;
}

static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
                                           struct pci_dev *bridge, int busnr)
{
        struct pci_bus *child;
        int i;
        int ret;

        /*
         * Allocate a new bus, and inherit stuff from the parent..
         */
        child = pci_alloc_bus(parent);
        if (!child)
                return NULL;

        child->parent = parent;
        child->ops = parent->ops;
        child->msi = parent->msi;
        child->sysdata = parent->sysdata;
        child->bus_flags = parent->bus_flags;

        /* initialize some portions of the bus device, but don't register it
         * now as the parent is not properly set up yet.
         */
        child->dev.class = &pcibus_class;
        dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);

        /*
         * Set up the primary, secondary and subordinate
         * bus numbers.
         */
        child->number = child->busn_res.start = busnr;
        child->primary = parent->busn_res.start;
        child->busn_res.end = 0xff;

        if (!bridge) {
                child->dev.parent = parent->bridge;
                goto add_dev;
        }

        child->self = bridge;
        child->bridge = get_device(&bridge->dev);
        child->dev.parent = child->bridge;
        pci_set_bus_of_node(child);
        pci_set_bus_speed(child);

        /* Set up default resource pointers and names.. */
        for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) {
                child->resource[i] = &bridge->resource[PCI_BRIDGE_RESOURCES+i];
                child->resource[i]->name = child->name;
        }
        bridge->subordinate = child;

add_dev:
        pci_set_bus_msi_domain(child);
        ret = device_register(&child->dev);
        WARN_ON(ret < 0);

        pcibios_add_bus(child);

        if (child->ops->add_bus) {
                ret = child->ops->add_bus(child);
                if (WARN_ON(ret < 0))
                        dev_err(&child->dev, "failed to add bus: %d\n", ret);
        }

        /* Create legacy_io and legacy_mem files for this bus */
        pci_create_legacy_files(child);

        return child;
}

struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
                                int busnr)
{
        struct pci_bus *child;

        child = pci_alloc_child_bus(parent, dev, busnr);
        if (child) {
                down_write(&pci_bus_sem);
                list_add_tail(&child->node, &parent->children);
                up_write(&pci_bus_sem);
        }
        return child;
}
EXPORT_SYMBOL(pci_add_new_bus);

static void pci_enable_crs(struct pci_dev *pdev)
{
        u16 root_cap = 0;

        /* Enable CRS Software Visibility if supported */
        pcie_capability_read_word(pdev, PCI_EXP_RTCAP, &root_cap);
        if (root_cap & PCI_EXP_RTCAP_CRSVIS)
                pcie_capability_set_word(pdev, PCI_EXP_RTCTL,
                                         PCI_EXP_RTCTL_CRSSVE);
}

/*
 * If it's a bridge, configure it and scan the bus behind it.
 * For CardBus bridges, we don't scan behind as the devices will
 * be handled by the bridge driver itself.
 *
 * We need to process bridges in two passes -- first we scan those
 * already configured by the BIOS and after we are done with all of
 * them, we proceed to assigning numbers to the remaining buses in
 * order to avoid overlaps between old and new bus numbers.
 */
int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
{
        struct pci_bus *child;
        int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
        u32 buses, i, j = 0;
        u16 bctl;
        u8 primary, secondary, subordinate;
        int broken = 0;

        /*
         * Make sure the bridge is powered on to be able to access config
         * space of devices below it.
         */
        pm_runtime_get_sync(&dev->dev);

        pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
        primary = buses & 0xFF;
        secondary = (buses >> 8) & 0xFF;
        subordinate = (buses >> 16) & 0xFF;

        dev_dbg(&dev->dev, "scanning [bus %02x-%02x] behind bridge, pass %d\n",
                secondary, subordinate, pass);

        if (!primary && (primary != bus->number) && secondary && subordinate) {
                dev_warn(&dev->dev, "Primary bus is hard wired to 0\n");
                primary = bus->number;
        }

        /* Check if setup is sensible at all */
        if (!pass &&
            (primary != bus->number || secondary <= bus->number ||
             secondary > subordinate)) {
                dev_info(&dev->dev, "bridge configuration invalid ([bus %02x-%02x]), reconfiguring\n",
                         secondary, subordinate);
                broken = 1;
        }

        /* Disable MasterAbortMode during probing to avoid reporting
           of bus errors (in some architectures) */
        pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &bctl);
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL,
                              bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT);

        pci_enable_crs(dev);

        if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
            !is_cardbus && !broken) {
                unsigned int cmax;
                /*
                 * Bus already configured by firmware, process it in the first
                 * pass and just note the configuration.
                 */
                if (pass)
                        goto out;

                /*
                 * The bus might already exist for two reasons: Either we are
                 * rescanning the bus or the bus is reachable through more than
                 * one bridge. The second case can happen with the i450NX
                 * chipset.
                 */
                child = pci_find_bus(pci_domain_nr(bus), secondary);
                if (!child) {
                        child = pci_add_new_bus(bus, dev, secondary);
                        if (!child)
                                goto out;
                        child->primary = primary;
                        pci_bus_insert_busn_res(child, secondary, subordinate);
                        child->bridge_ctl = bctl;
                }

                cmax = pci_scan_child_bus(child);
                if (cmax > subordinate)
                        dev_warn(&dev->dev, "bridge has subordinate %02x but max busn %02x\n",
                                 subordinate, cmax);
                /* subordinate should equal child->busn_res.end */
                if (subordinate > max)
                        max = subordinate;
        } else {
                /*
                 * We need to assign a number to this bus which we always
                 * do in the second pass.
                 */
                if (!pass) {
                        if (pcibios_assign_all_busses() || broken || is_cardbus)
                                /* Temporarily disable forwarding of the
                                   configuration cycles on all bridges in
                                   this bus segment to avoid possible
                                   conflicts in the second pass between two
                                   bridges programmed with overlapping
                                   bus ranges. */
                                pci_write_config_dword(dev, PCI_PRIMARY_BUS,
                                                       buses & ~0xffffff);
                        goto out;
                }

                /* Clear errors */
                pci_write_config_word(dev, PCI_STATUS, 0xffff);

                /* Prevent assigning a bus number that already exists.
                 * This can happen when a bridge is hot-plugged, so in
                 * this case we only re-scan this bus. */
                child = pci_find_bus(pci_domain_nr(bus), max+1);
                if (!child) {
                        child = pci_add_new_bus(bus, dev, max+1);
                        if (!child)
                                goto out;
                        pci_bus_insert_busn_res(child, max+1, 0xff);
                }
                max++;
                buses = (buses & 0xff000000)
                      | ((unsigned int)(child->primary)     <<  0)
                      | ((unsigned int)(child->busn_res.start)   <<  8)
                      | ((unsigned int)(child->busn_res.end) << 16);

                /*
                 * yenta.c forces a secondary latency timer of 176.
                 * Copy that behaviour here.
                 */
                if (is_cardbus) {
                        buses &= ~0xff000000;
                        buses |= CARDBUS_LATENCY_TIMER << 24;
                }

                /*
                 * We need to blast all three values with a single write.
                 */
                pci_write_config_dword(dev, PCI_PRIMARY_BUS, buses);

                if (!is_cardbus) {
                        child->bridge_ctl = bctl;
                        max = pci_scan_child_bus(child);
                } else {
                        /*
                         * For CardBus bridges, we leave 4 bus numbers
                         * as cards with a PCI-to-PCI bridge can be
                         * inserted later.
                         */
                        for (i = 0; i < CARDBUS_RESERVE_BUSNR; i++) {
                                struct pci_bus *parent = bus;
                                if (pci_find_bus(pci_domain_nr(bus),
                                                        max+i+1))
                                        break;
                                while (parent->parent) {
                                        if ((!pcibios_assign_all_busses()) &&
                                            (parent->busn_res.end > max) &&
                                            (parent->busn_res.end <= max+i)) {
                                                j = 1;
                                        }
                                        parent = parent->parent;
                                }
                                if (j) {
                                        /*
                                         * Often, there are two cardbus bridges
                                         * -- try to leave one valid bus number
                                         * for each one.
                                         */
                                        i /= 2;
                                        break;
                                }
                        }
                        max += i;
                }
                /*
                 * Set the subordinate bus number to its real value.
                 */
                pci_bus_update_busn_res_end(child, max);
                pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
        }

        sprintf(child->name,
                (is_cardbus ? "PCI CardBus %04x:%02x" : "PCI Bus %04x:%02x"),
                pci_domain_nr(bus), child->number);

        /* Has only triggered on CardBus, fixup is in yenta_socket */
        while (bus->parent) {
                if ((child->busn_res.end > bus->busn_res.end) ||
                    (child->number > bus->busn_res.end) ||
                    (child->number < bus->number) ||
                    (child->busn_res.end < bus->number)) {
                        dev_info(&child->dev, "%pR %s hidden behind%s bridge %s %pR\n",
                                &child->busn_res,
                                (bus->number > child->busn_res.end &&
                                 bus->busn_res.end < child->number) ?
                                        "wholly" : "partially",
                                bus->self->transparent ? " transparent" : "",
                                dev_name(&bus->dev),
                                &bus->busn_res);
                }
                bus = bus->parent;
        }

out:
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);

        pm_runtime_put(&dev->dev);

        return max;
}
EXPORT_SYMBOL(pci_scan_bridge);

/*
 * Read interrupt line and base address registers.
 * The architecture-dependent code can tweak these, of course.
 */
static void pci_read_irq(struct pci_dev *dev)
{
        unsigned char irq;

        pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &irq);
        dev->pin = irq;
        if (irq)
                pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq);
        dev->irq = irq;
}

void set_pcie_port_type(struct pci_dev *pdev)
{
        int pos;
        u16 reg16;
        int type;
        struct pci_dev *parent;

        pos = pci_find_capability(pdev, PCI_CAP_ID_EXP);
        if (!pos)
                return;

        pdev->pcie_cap = pos;
        pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
        pdev->pcie_flags_reg = reg16;
        pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
        pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;

        /*
         * A Root Port or a PCI-to-PCIe bridge is always the upstream end
         * of a Link.  No PCIe component has two Links.  Two Links are
         * connected by a Switch that has a Port on each Link and internal
         * logic to connect the two Ports.
         */
        type = pci_pcie_type(pdev);
        if (type == PCI_EXP_TYPE_ROOT_PORT ||
            type == PCI_EXP_TYPE_PCIE_BRIDGE)
                pdev->has_secondary_link = 1;
        else if (type == PCI_EXP_TYPE_UPSTREAM ||
                 type == PCI_EXP_TYPE_DOWNSTREAM) {
                parent = pci_upstream_bridge(pdev);

                /*
                 * Usually there's an upstream device (Root Port or Switch
                 * Downstream Port), but we can't assume one exists.
                 */
                if (parent && !parent->has_secondary_link)
                        pdev->has_secondary_link = 1;
        }
}

void set_pcie_hotplug_bridge(struct pci_dev *pdev)
{
        u32 reg32;

        pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &reg32);
        if (reg32 & PCI_EXP_SLTCAP_HPC)
                pdev->is_hotplug_bridge = 1;
}

static void set_pcie_thunderbolt(struct pci_dev *dev)
{
        int vsec = 0;
        u32 header;

        while ((vsec = pci_find_next_ext_capability(dev, vsec,
                                                    PCI_EXT_CAP_ID_VNDR))) {
                pci_read_config_dword(dev, vsec + PCI_VNDR_HEADER, &header);

                /* Is the device part of a Thunderbolt controller? */
                if (dev->vendor == PCI_VENDOR_ID_INTEL &&
                    PCI_VNDR_HEADER_ID(header) == PCI_VSEC_ID_INTEL_TBT) {
                        dev->is_thunderbolt = 1;
                        return;
                }
        }
}

/**
 * pci_ext_cfg_is_aliased - is ext config space just an alias of std config?
 * @dev: PCI device
 *
 * PCI Express to PCI/PCI-X Bridge Specification, rev 1.0, 4.1.4 says that
 * when forwarding a type1 configuration request the bridge must check that
 * the extended register address field is zero.  The bridge is not permitted
 * to forward the transactions and must handle it as an Unsupported Request.
 * Some bridges do not follow this rule and simply drop the extended register
 * bits, resulting in the standard config space being aliased, every 256
 * bytes across the entire configuration space.  Test for this condition by
 * comparing the first dword of each potential alias to the vendor/device ID.
 * Known offenders:
 *   ASM1083/1085 PCIe-to-PCI Reversible Bridge (1b21:1080, rev 01 & 03)
 *   AMD/ATI SBx00 PCI to PCI Bridge (1002:4384, rev 40)
 */
static bool pci_ext_cfg_is_aliased(struct pci_dev *dev)
{
#ifdef CONFIG_PCI_QUIRKS
        int pos;
        u32 header, tmp;

        pci_read_config_dword(dev, PCI_VENDOR_ID, &header);

        for (pos = PCI_CFG_SPACE_SIZE;
             pos < PCI_CFG_SPACE_EXP_SIZE; pos += PCI_CFG_SPACE_SIZE) {
                if (pci_read_config_dword(dev, pos, &tmp) != PCIBIOS_SUCCESSFUL
                    || header != tmp)
                        return false;
        }

        return true;
#else
        return false;
#endif
}

/**
 * pci_cfg_space_size - get the configuration space size of the PCI device.
 * @dev: PCI device
 *
 * Regular PCI devices have 256 bytes, but PCI-X 2 and PCI Express devices
 * have 4096 bytes.  Even if the device is capable, that doesn't mean we can
 * access it.  Maybe we don't have a way to generate extended config space
 * accesses, or the device is behind a reverse Express bridge.  So we try
 * reading the dword at 0x100 which must either be 0 or a valid extended
 * capability header.
 */
static int pci_cfg_space_size_ext(struct pci_dev *dev)
{
        u32 status;
        int pos = PCI_CFG_SPACE_SIZE;

        if (pci_read_config_dword(dev, pos, &status) != PCIBIOS_SUCCESSFUL)
                return PCI_CFG_SPACE_SIZE;
        if (status == 0xffffffff || pci_ext_cfg_is_aliased(dev))
                return PCI_CFG_SPACE_SIZE;

        return PCI_CFG_SPACE_EXP_SIZE;
}

int pci_cfg_space_size(struct pci_dev *dev)
{
        int pos;
        u32 status;
        u16 class;

        class = dev->class >> 8;
        if (class == PCI_CLASS_BRIDGE_HOST)
                return pci_cfg_space_size_ext(dev);

        if (pci_is_pcie(dev))
                return pci_cfg_space_size_ext(dev);

        pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
        if (!pos)
                return PCI_CFG_SPACE_SIZE;

        pci_read_config_dword(dev, pos + PCI_X_STATUS, &status);
        if (status & (PCI_X_STATUS_266MHZ | PCI_X_STATUS_533MHZ))
                return pci_cfg_space_size_ext(dev);

        return PCI_CFG_SPACE_SIZE;
}

#define LEGACY_IO_RESOURCE      (IORESOURCE_IO | IORESOURCE_PCI_FIXED)

static void pci_msi_setup_pci_dev(struct pci_dev *dev)
{
        /*
         * Disable the MSI hardware to avoid screaming interrupts
         * during boot.  This is the power on reset default so
         * usually this should be a noop.
         */
        dev->msi_cap = pci_find_capability(dev, PCI_CAP_ID_MSI);
        if (dev->msi_cap)
                pci_msi_set_enable(dev, 0);

        dev->msix_cap = pci_find_capability(dev, PCI_CAP_ID_MSIX);
        if (dev->msix_cap)
                pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
}

/**
 * pci_intx_mask_broken - test PCI_COMMAND_INTX_DISABLE writability
 * @dev: PCI device
 *
 * Test whether PCI_COMMAND_INTX_DISABLE is writable for @dev.  Check this
 * at enumeration-time to avoid modifying PCI_COMMAND at run-time.
 */
static int pci_intx_mask_broken(struct pci_dev *dev)
{
        u16 orig, toggle, new;

        pci_read_config_word(dev, PCI_COMMAND, &orig);
        toggle = orig ^ PCI_COMMAND_INTX_DISABLE;
        pci_write_config_word(dev, PCI_COMMAND, toggle);
        pci_read_config_word(dev, PCI_COMMAND, &new);

        pci_write_config_word(dev, PCI_COMMAND, orig);

        /*
         * PCI_COMMAND_INTX_DISABLE was reserved and read-only prior to PCI
         * r2.3, so strictly speaking, a device is not *broken* if it's not
         * writable.  But we'll live with the misnomer for now.
         */
        if (new != toggle)
                return 1;
        return 0;
}

/**
 * pci_setup_device - fill in class and map information of a device
 * @dev: the device structure to fill
 *
 * Initialize the device structure with information about the device's
 * vendor,class,memory and IO-space addresses,IRQ lines etc.
 * Called at initialisation of the PCI subsystem and by CardBus services.
 * Returns 0 on success and negative if unknown type of device (not normal,
 * bridge or CardBus).
 */
int pci_setup_device(struct pci_dev *dev)
{
        u32 class;
        u16 cmd;
        u8 hdr_type;
        int pos = 0;
        struct pci_bus_region region;
        struct resource *res;

        if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type))
                return -EIO;

        dev->sysdata = dev->bus->sysdata;
        dev->dev.parent = dev->bus->bridge;
        dev->dev.bus = &pci_bus_type;
        dev->hdr_type = hdr_type & 0x7f;
        dev->multifunction = !!(hdr_type & 0x80);
        dev->error_state = pci_channel_io_normal;
        set_pcie_port_type(dev);

        pci_dev_assign_slot(dev);
        /* Assume 32-bit PCI; let 64-bit PCI cards (which are far rarer)
           set this higher, assuming the system even supports it.  */
        dev->dma_mask = 0xffffffff;

        dev_set_name(&dev->dev, "%04x:%02x:%02x.%d", pci_domain_nr(dev->bus),
                     dev->bus->number, PCI_SLOT(dev->devfn),
                     PCI_FUNC(dev->devfn));

        pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
        dev->revision = class & 0xff;
        dev->class = class >> 8;                    /* upper 3 bytes */

        dev_printk(KERN_DEBUG, &dev->dev, "[%04x:%04x] type %02x class %#08x\n",
                   dev->vendor, dev->device, dev->hdr_type, dev->class);

        /* need to have dev->class ready */
        dev->cfg_size = pci_cfg_space_size(dev);

        /* need to have dev->cfg_size ready */
        set_pcie_thunderbolt(dev);

        /* "Unknown power state" */
        dev->current_state = PCI_UNKNOWN;

        /* Early fixups, before probing the BARs */
        pci_fixup_device(pci_fixup_early, dev);
        /* device class may be changed after fixup */
        class = dev->class >> 8;

        if (dev->non_compliant_bars) {
                pci_read_config_word(dev, PCI_COMMAND, &cmd);
                if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
                        dev_info(&dev->dev, "device has non-compliant BARs; disabling IO/MEM decoding\n");
                        cmd &= ~PCI_COMMAND_IO;
                        cmd &= ~PCI_COMMAND_MEMORY;
                        pci_write_config_word(dev, PCI_COMMAND, cmd);
                }
        }

        dev->broken_intx_masking = pci_intx_mask_broken(dev);

        switch (dev->hdr_type) {                    /* header type */
        case PCI_HEADER_TYPE_NORMAL:                /* standard header */
                if (class == PCI_CLASS_BRIDGE_PCI)
                        goto bad;
                pci_read_irq(dev);
                pci_read_bases(dev, 6, PCI_ROM_ADDRESS);
                pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor);
                pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device);

                /*
                 * Do the ugly legacy mode stuff here rather than broken chip
                 * quirk code. Legacy mode ATA controllers have fixed
                 * addresses. These are not always echoed in BAR0-3, and
                 * BAR0-3 in a few cases contain junk!
                 */
                if (class == PCI_CLASS_STORAGE_IDE) {
                        u8 progif;
                        pci_read_config_byte(dev, PCI_CLASS_PROG, &progif);
                        if ((progif & 1) == 0) {
                                region.start = 0x1F0;
                                region.end = 0x1F7;
                                res = &dev->resource[0];
                                res->flags = LEGACY_IO_RESOURCE;
                                pcibios_bus_to_resource(dev->bus, res, &region);
                                dev_info(&dev->dev, "legacy IDE quirk: reg 0x10: %pR\n",
                                         res);
                                region.start = 0x3F6;
                                region.end = 0x3F6;
                                res = &dev->resource[1];
                                res->flags = LEGACY_IO_RESOURCE;
                                pcibios_bus_to_resource(dev->bus, res, &region);
                                dev_info(&dev->dev, "legacy IDE quirk: reg 0x14: %pR\n",
                                         res);
                        }
                        if ((progif & 4) == 0) {
                                region.start = 0x170;
                                region.end = 0x177;
                                res = &dev->resource[2];
                                res->flags = LEGACY_IO_RESOURCE;
                                pcibios_bus_to_resource(dev->bus, res, &region);
                                dev_info(&dev->dev, "legacy IDE quirk: reg 0x18: %pR\n",
                                         res);
                                region.start = 0x376;
                                region.end = 0x376;
                                res = &dev->resource[3];
                                res->flags = LEGACY_IO_RESOURCE;
                                pcibios_bus_to_resource(dev->bus, res, &region);
                                dev_info(&dev->dev, "legacy IDE quirk: reg 0x1c: %pR\n",
                                         res);
                        }
                }
                break;

        case PCI_HEADER_TYPE_BRIDGE:                /* bridge header */
                if (class != PCI_CLASS_BRIDGE_PCI)
                        goto bad;
                /* The PCI-to-PCI bridge spec requires that subtractive
                   decoding (i.e. transparent) bridge must have programming
                   interface code of 0x01. */
                pci_read_irq(dev);
                dev->transparent = ((dev->class & 0xff) == 1);
                pci_read_bases(dev, 2, PCI_ROM_ADDRESS1);
                set_pcie_hotplug_bridge(dev);
                pos = pci_find_capability(dev, PCI_CAP_ID_SSVID);
                if (pos) {
                        pci_read_config_word(dev, pos + PCI_SSVID_VENDOR_ID, &dev->subsystem_vendor);
                        pci_read_config_word(dev, pos + PCI_SSVID_DEVICE_ID, &dev->subsystem_device);
                }
                break;

        case PCI_HEADER_TYPE_CARDBUS:               /* CardBus bridge header */
                if (class != PCI_CLASS_BRIDGE_CARDBUS)
                        goto bad;
                pci_read_irq(dev);
                pci_read_bases(dev, 1, 0);
                pci_read_config_word(dev, PCI_CB_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor);
                pci_read_config_word(dev, PCI_CB_SUBSYSTEM_ID, &dev->subsystem_device);
                break;

        default:                                    /* unknown header */
                dev_err(&dev->dev, "unknown header type %02x, ignoring device\n",
                        dev->hdr_type);
                return -EIO;

        bad:
                dev_err(&dev->dev, "ignoring class %#08x (doesn't match header type %02x)\n",
                        dev->class, dev->hdr_type);
                dev->class = PCI_CLASS_NOT_DEFINED << 8;
        }

        /* We found a fine healthy device, go go go... */
        return 0;
}

static void pci_configure_mps(struct pci_dev *dev)
{
        struct pci_dev *bridge = pci_upstream_bridge(dev);
        int mps, p_mps, rc;

        if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge))
                return;

        mps = pcie_get_mps(dev);
        p_mps = pcie_get_mps(bridge);

        if (mps == p_mps)
                return;

        if (pcie_bus_config == PCIE_BUS_TUNE_OFF) {
                dev_warn(&dev->dev, "Max Payload Size %d, but upstream %s set to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n",
                         mps, pci_name(bridge), p_mps);
                return;
        }

        /*
         * Fancier MPS configuration is done later by
         * pcie_bus_configure_settings()
         */
        if (pcie_bus_config != PCIE_BUS_DEFAULT)
                return;

        rc = pcie_set_mps(dev, p_mps);
        if (rc) {
                dev_warn(&dev->dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n",
                         p_mps);
                return;
        }

        dev_info(&dev->dev, "Max Payload Size set to %d (was %d, max %d)\n",
                 p_mps, mps, 128 << dev->pcie_mpss);
}

static struct hpp_type0 pci_default_type0 = {
        .revision = 1,
        .cache_line_size = 8,
        .latency_timer = 0x40,
        .enable_serr = 0,
        .enable_perr = 0,
};

static void program_hpp_type0(struct pci_dev *dev, struct hpp_type0 *hpp)
{
        u16 pci_cmd, pci_bctl;

        if (!hpp)
                hpp = &pci_default_type0;

        if (hpp->revision > 1) {
                dev_warn(&dev->dev,
                         "PCI settings rev %d not supported; using defaults\n",
                         hpp->revision);
                hpp = &pci_default_type0;
        }

        pci_write_config_byte(dev, PCI_CACHE_LINE_SIZE, hpp->cache_line_size);
        pci_write_config_byte(dev, PCI_LATENCY_TIMER, hpp->latency_timer);
        pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
        if (hpp->enable_serr)
                pci_cmd |= PCI_COMMAND_SERR;
        if (hpp->enable_perr)
                pci_cmd |= PCI_COMMAND_PARITY;
        pci_write_config_word(dev, PCI_COMMAND, pci_cmd);

        /* Program bridge control value */
        if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI) {
                pci_write_config_byte(dev, PCI_SEC_LATENCY_TIMER,
                                      hpp->latency_timer);
                pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &pci_bctl);
                if (hpp->enable_serr)
                        pci_bctl |= PCI_BRIDGE_CTL_SERR;
                if (hpp->enable_perr)
                        pci_bctl |= PCI_BRIDGE_CTL_PARITY;
                pci_write_config_word(dev, PCI_BRIDGE_CONTROL, pci_bctl);
        }
}

static void program_hpp_type1(struct pci_dev *dev, struct hpp_type1 *hpp)
{
        int pos;

        if (!hpp)
                return;

        pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
        if (!pos)
                return;

        dev_warn(&dev->dev, "PCI-X settings not supported\n");
}

static bool pcie_root_rcb_set(struct pci_dev *dev)
{
        struct pci_dev *rp = pcie_find_root_port(dev);
        u16 lnkctl;

        if (!rp)
                return false;

        pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
        if (lnkctl & PCI_EXP_LNKCTL_RCB)
                return true;

        return false;
}

static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
{
        int pos;
        u32 reg32;

        if (!hpp)
                return;

        if (!pci_is_pcie(dev))
                return;

        if (hpp->revision > 1) {
                dev_warn(&dev->dev, "PCIe settings rev %d not supported\n",
                         hpp->revision);
                return;
        }

        /*
         * Don't allow _HPX to change MPS or MRRS settings.  We manage
         * those to make sure they're consistent with the rest of the
         * platform.
         */
        hpp->pci_exp_devctl_and |= PCI_EXP_DEVCTL_PAYLOAD |
                                    PCI_EXP_DEVCTL_READRQ;
        hpp->pci_exp_devctl_or &= ~(PCI_EXP_DEVCTL_PAYLOAD |
                                    PCI_EXP_DEVCTL_READRQ);

        /* Initialize Device Control Register */
        pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
                        ~hpp->pci_exp_devctl_and, hpp->pci_exp_devctl_or);

        /* Initialize Link Control Register */
        if (pcie_cap_has_lnkctl(dev)) {

                /*
                 * If the Root Port supports Read Completion Boundary of
                 * 128, set RCB to 128.  Otherwise, clear it.
                 */
                hpp->pci_exp_lnkctl_and |= PCI_EXP_LNKCTL_RCB;
                hpp->pci_exp_lnkctl_or &= ~PCI_EXP_LNKCTL_RCB;
                if (pcie_root_rcb_set(dev))
                        hpp->pci_exp_lnkctl_or |= PCI_EXP_LNKCTL_RCB;

                pcie_capability_clear_and_set_word(dev, PCI_EXP_LNKCTL,
                        ~hpp->pci_exp_lnkctl_and, hpp->pci_exp_lnkctl_or);
        }

        /* Find Advanced Error Reporting Enhanced Capability */
        pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
        if (!pos)
                return;

        /* Initialize Uncorrectable Error Mask Register */
        pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, &reg32);
        reg32 = (reg32 & hpp->unc_err_mask_and) | hpp->unc_err_mask_or;
        pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, reg32);

        /* Initialize Uncorrectable Error Severity Register */
        pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, &reg32);
        reg32 = (reg32 & hpp->unc_err_sever_and) | hpp->unc_err_sever_or;
        pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, reg32);

        /* Initialize Correctable Error Mask Register */
        pci_read_config_dword(dev, pos + PCI_ERR_COR_MASK, &reg32);
        reg32 = (reg32 & hpp->cor_err_mask_and) | hpp->cor_err_mask_or;
        pci_write_config_dword(dev, pos + PCI_ERR_COR_MASK, reg32);

        /* Initialize Advanced Error Capabilities and Control Register */
        pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
        reg32 = (reg32 & hpp->adv_err_cap_and) | hpp->adv_err_cap_or;
        /* Don't enable ECRC generation or checking if unsupported */
        if (!(reg32 & PCI_ERR_CAP_ECRC_GENC))
                reg32 &= ~PCI_ERR_CAP_ECRC_GENE;
        if (!(reg32 & PCI_ERR_CAP_ECRC_CHKC))
                reg32 &= ~PCI_ERR_CAP_ECRC_CHKE;
        pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);

        /*
         * FIXME: The following two registers are not supported yet.
         *
         *   o Secondary Uncorrectable Error Severity Register
         *   o Secondary Uncorrectable Error Mask Register
         */
}

static void pci_configure_extended_tags(struct pci_dev *dev)
{
        u32 dev_cap;
        int ret;

        if (!pci_is_pcie(dev))
                return;

        ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &dev_cap);
        if (ret)
                return;

        if (dev_cap & PCI_EXP_DEVCAP_EXT_TAG)
                pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
                                         PCI_EXP_DEVCTL_EXT_TAG);
}

static void pci_configure_device(struct pci_dev *dev)
{
        struct hotplug_params hpp;
        int ret;

        pci_configure_mps(dev);
        pci_configure_extended_tags(dev);

        memset(&hpp, 0, sizeof(hpp));
        ret = pci_get_hp_params(dev, &hpp);
        if (ret)
                return;

        program_hpp_type2(dev, hpp.t2);
        program_hpp_type1(dev, hpp.t1);
        program_hpp_type0(dev, hpp.t0);
}

static void pci_release_capabilities(struct pci_dev *dev)
{
        pci_vpd_release(dev);
        pci_iov_release(dev);
        pci_free_cap_save_buffers(dev);
}

/**
 * pci_release_dev - free a pci device structure when all users of it are finished.
 * @dev: device that's been disconnected
 *
 * Will be called only by the device core when all users of this pci device are
 * done.
 */
static void pci_release_dev(struct device *dev)
{
        struct pci_dev *pci_dev;

        pci_dev = to_pci_dev(dev);
        pci_release_capabilities(pci_dev);
        pci_release_of_node(pci_dev);
        pcibios_release_device(pci_dev);
        pci_bus_put(pci_dev->bus);
        kfree(pci_dev->driver_override);
        kfree(pci_dev->dma_alias_mask);
        kfree(pci_dev);
}

struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
{
        struct pci_dev *dev;

        dev = kzalloc(sizeof(struct pci_dev), GFP_KERNEL);
        if (!dev)
                return NULL;

        INIT_LIST_HEAD(&dev->bus_list);
        dev->dev.type = &pci_dev_type;
        dev->bus = pci_bus_get(bus);

        return dev;
}
EXPORT_SYMBOL(pci_alloc_dev);

bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
                                int crs_timeout)
{
        int delay = 1;

        if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
                return false;

        /* some broken boards return 0 or ~0 if a slot is empty: */
        if (*l == 0xffffffff || *l == 0x00000000 ||
            *l == 0x0000ffff || *l == 0xffff0000)
                return false;

        /*
         * Configuration Request Retry Status.  Some root ports return the
         * actual device ID instead of the synthetic ID (0xFFFF) required
         * by the PCIe spec.  Ignore the device ID and only check for
         * (vendor id == 1).
         */
        while ((*l & 0xffff) == 0x0001) {
                if (!crs_timeout)
                        return false;

                msleep(delay);
                delay *= 2;
                if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
                        return false;
                /* Card hasn't responded in 60 seconds?  Must be stuck. */
                if (delay > crs_timeout) {
                        printk(KERN_WARNING "pci %04x:%02x:%02x.%d: not responding\n",
                               pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
                               PCI_FUNC(devfn));
                        return false;
                }
        }

        return true;
}
EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);

/*
 * Read the config data for a PCI device, sanity-check it
 * and fill in the dev structure...
 */
static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
{
        struct pci_dev *dev;
        u32 l;

        if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, 60*1000))
                return NULL;

        dev = pci_alloc_dev(bus);
        if (!dev)
                return NULL;

        dev->devfn = devfn;
        dev->vendor = l & 0xffff;
        dev->device = (l >> 16) & 0xffff;

        pci_set_of_node(dev);

        if (pci_setup_device(dev)) {
                pci_bus_put(dev->bus);
                kfree(dev);
                return NULL;
        }

        return dev;
}

static void pci_init_capabilities(struct pci_dev *dev)
{
        /* Enhanced Allocation */
        pci_ea_init(dev);

        /* Setup MSI caps & disable MSI/MSI-X interrupts */
        pci_msi_setup_pci_dev(dev);

        /* Buffers for saving PCIe and PCI-X capabilities */
        pci_allocate_cap_save_buffers(dev);

        /* Power Management */
        pci_pm_init(dev);

        /* Vital Product Data */
        pci_vpd_init(dev);

        /* Alternative Routing-ID Forwarding */
        pci_configure_ari(dev);

        /* Single Root I/O Virtualization */
        pci_iov_init(dev);

        /* Address Translation Services */
        pci_ats_init(dev);

        /* Enable ACS P2P upstream forwarding */
        pci_enable_acs(dev);

        /* Precision Time Measurement */
        pci_ptm_init(dev);

        /* Advanced Error Reporting */
        pci_aer_init(dev);
}

/*
 * This is the equivalent of pci_host_bridge_msi_domain that acts on
 * devices. Firmware interfaces that can select the MSI domain on a
 * per-device basis should be called from here.
 */
static struct irq_domain *pci_dev_msi_domain(struct pci_dev *dev)
{
        struct irq_domain *d;

        /*
         * If a domain has been set through the pcibios_add_device
         * callback, then this is the one (platform code knows best).
         */
        d = dev_get_msi_domain(&dev->dev);
        if (d)
                return d;

        /*
         * Let's see if we have a firmware interface able to provide
         * the domain.
         */
        d = pci_msi_get_device_domain(dev);
        if (d)
                return d;

        return NULL;
}

static void pci_set_msi_domain(struct pci_dev *dev)
{
        struct irq_domain *d;

        /*
         * If the platform or firmware interfaces cannot supply a
         * device-specific MSI domain, then inherit the default domain
         * from the host bridge itself.
         */
        d = pci_dev_msi_domain(dev);
        if (!d)
                d = dev_get_msi_domain(&dev->bus->dev);

        dev_set_msi_domain(&dev->dev, d);
}

void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
{
        int ret;

        pci_configure_device(dev);

        device_initialize(&dev->dev);
        dev->dev.release = pci_release_dev;

        set_dev_node(&dev->dev, pcibus_to_node(bus));
        dev->dev.dma_mask = &dev->dma_mask;
        dev->dev.dma_parms = &dev->dma_parms;
        dev->dev.coherent_dma_mask = 0xffffffffull;

        pci_set_dma_max_seg_size(dev, 65536);
        pci_set_dma_seg_boundary(dev, 0xffffffff);

        /* Fix up broken headers */
        pci_fixup_device(pci_fixup_header, dev);

        /* moved out from quirk header fixup code */
        pci_reassigndev_resource_alignment(dev);

        /* Clear the state_saved flag. */
        dev->state_saved = false;

        /* Initialize various capabilities */
        pci_init_capabilities(dev);

        /*
         * Add the device to our list of discovered devices
         * and the bus list for fixup functions, etc.
         */
        down_write(&pci_bus_sem);
        list_add_tail(&dev->bus_list, &bus->devices);
        up_write(&pci_bus_sem);

        ret = pcibios_add_device(dev);
        WARN_ON(ret < 0);

        /* Setup MSI irq domain */
        pci_set_msi_domain(dev);

        /* Notifier could use PCI capabilities */
        dev->match_driver = false;
        ret = device_add(&dev->dev);
        WARN_ON(ret < 0);
}

struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn)
{
        struct pci_dev *dev;

        dev = pci_get_slot(bus, devfn);
        if (dev) {
                pci_dev_put(dev);
                return dev;
        }

        dev = pci_scan_device(bus, devfn);
        if (!dev)
                return NULL;

        pci_device_add(dev, bus);

        return dev;
}
EXPORT_SYMBOL(pci_scan_single_device);

static unsigned next_fn(struct pci_bus *bus, struct pci_dev *dev, unsigned fn)
{
        int pos;
        u16 cap = 0;
        unsigned next_fn;

        if (pci_ari_enabled(bus)) {
                if (!dev)
                        return 0;
                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
                if (!pos)
                        return 0;

                pci_read_config_word(dev, pos + PCI_ARI_CAP, &cap);
                next_fn = PCI_ARI_CAP_NFN(cap);
                if (next_fn <= fn)
                        return 0;       /* protect against malformed list */

                return next_fn;
        }

        /* dev may be NULL for non-contiguous multifunction devices */
        if (!dev || dev->multifunction)
                return (fn + 1) % 8;

        return 0;
}

static int only_one_child(struct pci_bus *bus)
{
        struct pci_dev *parent = bus->self;

        if (!parent || !pci_is_pcie(parent))
                return 0;
        if (pci_pcie_type(parent) == PCI_EXP_TYPE_ROOT_PORT)
                return 1;

        /*
         * PCIe downstream ports are bridges that normally lead to only a
         * device 0, but if PCI_SCAN_ALL_PCIE_DEVS is set, scan all
         * possible devices, not just device 0.  See PCIe spec r3.0,
         * sec 7.3.1.
         */
        if (parent->has_secondary_link &&
            !pci_has_flag(PCI_SCAN_ALL_PCIE_DEVS))
                return 1;
        return 0;
}

/**
 * pci_scan_slot - scan a PCI slot on a bus for devices.
 * @bus: PCI bus to scan
 * @devfn: slot number to scan (must have zero function.)
 *
 * Scan a PCI slot on the specified PCI bus for devices, adding
 * discovered devices to the @bus->devices list.  New devices
 * will not have is_added set.
 *
 * Returns the number of new devices found.
 */
int pci_scan_slot(struct pci_bus *bus, int devfn)
{
        unsigned fn, nr = 0;
        struct pci_dev *dev;

        if (only_one_child(bus) && (devfn > 0))
                return 0; /* Already scanned the entire slot */

        dev = pci_scan_single_device(bus, devfn);
        if (!dev)
                return 0;
        if (!dev->is_added)
                nr++;

        for (fn = next_fn(bus, dev, 0); fn > 0; fn = next_fn(bus, dev, fn)) {
                dev = pci_scan_single_device(bus, devfn + fn);
                if (dev) {
                        if (!dev->is_added)
                                nr++;
                        dev->multifunction = 1;
                }
        }

        /* only one slot has pcie device */
        if (bus->self && nr)
                pcie_aspm_init_link_state(bus->self);

        return nr;
}
EXPORT_SYMBOL(pci_scan_slot);

static int pcie_find_smpss(struct pci_dev *dev, void *data)
{
        u8 *smpss = data;

        if (!pci_is_pcie(dev))
                return 0;

        /*
         * We don't have a way to change MPS settings on devices that have
         * drivers attached.  A hot-added device might support only the minimum
         * MPS setting (MPS=128).  Therefore, if the fabric contains a bridge
         * where devices may be hot-added, we limit the fabric MPS to 128 so
         * hot-added devices will work correctly.
         *
         * However, if we hot-add a device to a slot directly below a Root
         * Port, it's impossible for there to be other existing devices below
         * the port.  We don't limit the MPS in this case because we can
         * reconfigure MPS on both the Root Port and the hot-added device,
         * and there are no other devices involved.
         *
         * Note that this PCIE_BUS_SAFE path assumes no peer-to-peer DMA.
         */
        if (dev->is_hotplug_bridge &&
            pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT)
                *smpss = 0;

        if (*smpss > dev->pcie_mpss)
                *smpss = dev->pcie_mpss;

        return 0;
}

static void pcie_write_mps(struct pci_dev *dev, int mps)
{
        int rc;

        if (pcie_bus_config == PCIE_BUS_PERFORMANCE) {
                mps = 128 << dev->pcie_mpss;

                if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT &&
                    dev->bus->self)
                        /* For "Performance", the assumption is made that
                         * downstream communication will never be larger than
                         * the MRRS.  So, the MPS only needs to be configured
                         * for the upstream communication.  This being the case,
                         * walk from the top down and set the MPS of the child
                         * to that of the parent bus.
                         *
                         * Configure the device MPS with the smaller of the
                         * device MPSS or the bridge MPS (which is assumed to be
                         * properly configured at this point to the largest
                         * allowable MPS based on its parent bus).
                         */
                        mps = min(mps, pcie_get_mps(dev->bus->self));
        }

        rc = pcie_set_mps(dev, mps);
        if (rc)
                dev_err(&dev->dev, "Failed attempting to set the MPS\n");
}

static void pcie_write_mrrs(struct pci_dev *dev)
{
        int rc, mrrs;

        /* In the "safe" case, do not configure the MRRS.  There appear to be
         * issues with setting MRRS to 0 on a number of devices.
         */
        if (pcie_bus_config != PCIE_BUS_PERFORMANCE)
                return;

        /* For Max performance, the MRRS must be set to the largest supported
         * value.  However, it cannot be configured larger than the MPS the
         * device or the bus can support.  This should already be properly
         * configured by a prior call to pcie_write_mps.
         */
        mrrs = pcie_get_mps(dev);

        /* MRRS is a R/W register.  Invalid values can be written, but a
         * subsequent read will verify if the value is acceptable or not.
         * If the MRRS value provided is not acceptable (e.g., too large),
         * shrink the value until it is acceptable to the HW.
         */
        while (mrrs != pcie_get_readrq(dev) && mrrs >= 128) {
                rc = pcie_set_readrq(dev, mrrs);
                if (!rc)
                        break;

                dev_warn(&dev->dev, "Failed attempting to set the MRRS\n");
                mrrs /= 2;
        }

        if (mrrs < 128)
                dev_err(&dev->dev, "MRRS was unable to be configured with a safe value.  If problems are experienced, try running with pci=pcie_bus_safe\n");
}

static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
{
        int mps, orig_mps;

        if (!pci_is_pcie(dev))
                return 0;

        if (pcie_bus_config == PCIE_BUS_TUNE_OFF ||
            pcie_bus_config == PCIE_BUS_DEFAULT)
                return 0;

        mps = 128 << *(u8 *)data;
        orig_mps = pcie_get_mps(dev);

        pcie_write_mps(dev, mps);
        pcie_write_mrrs(dev);

        dev_info(&dev->dev, "Max Payload Size set to %4d/%4d (was %4d), Max Read Rq %4d\n",
                 pcie_get_mps(dev), 128 << dev->pcie_mpss,
                 orig_mps, pcie_get_readrq(dev));

        return 0;
}

/* pcie_bus_configure_settings requires that pci_walk_bus work in a top-down,
 * parents then children fashion.  If this changes, then this code will not
 * work as designed.
 */
void pcie_bus_configure_settings(struct pci_bus *bus)
{
        u8 smpss = 0;

        if (!bus->self)
                return;

        if (!pci_is_pcie(bus->self))
                return;

        /* FIXME - Peer to peer DMA is possible, though the endpoint would need
         * to be aware of the MPS of the destination.  To work around this,
         * simply force the MPS of the entire system to the smallest possible.
         */
        if (pcie_bus_config == PCIE_BUS_PEER2PEER)
                smpss = 0;

        if (pcie_bus_config == PCIE_BUS_SAFE) {
                smpss = bus->self->pcie_mpss;

                pcie_find_smpss(bus->self, &smpss);
                pci_walk_bus(bus, pcie_find_smpss, &smpss);
        }

        pcie_bus_configure_set(bus->self, &smpss);
        pci_walk_bus(bus, pcie_bus_configure_set, &smpss);
}
EXPORT_SYMBOL_GPL(pcie_bus_configure_settings);

unsigned int pci_scan_child_bus(struct pci_bus *bus)
{
        unsigned int devfn, pass, max = bus->busn_res.start;
        struct pci_dev *dev;

        dev_dbg(&bus->dev, "scanning bus\n");

        /* Go find them, Rover! */
        for (devfn = 0; devfn < 0x100; devfn += 8)
                pci_scan_slot(bus, devfn);

        /* Reserve buses for SR-IOV capability. */
        max += pci_iov_bus_range(bus);

        /*
         * After performing arch-dependent fixup of the bus, look behind
         * all PCI-to-PCI bridges on this bus.
         */
        if (!bus->is_added) {
                dev_dbg(&bus->dev, "fixups for bus\n");
                pcibios_fixup_bus(bus);
                bus->is_added = 1;
        }

        for (pass = 0; pass < 2; pass++)
                list_for_each_entry(dev, &bus->devices, bus_list) {
                        if (pci_is_bridge(dev))
                                max = pci_scan_bridge(bus, dev, max, pass);
                }

        /*
         * Make sure a hotplug bridge has at least the minimum requested
         * number of buses.
         */
        if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) {
                if (max - bus->busn_res.start < pci_hotplug_bus_size - 1)
                        max = bus->busn_res.start + pci_hotplug_bus_size - 1;
        }

        /*
         * We've scanned the bus and so we know all about what's on
         * the other side of any bridges that may be on this bus plus
         * any devices.
         *
         * Return how far we've got finding sub-buses.
         */
        dev_dbg(&bus->dev, "bus scan returning with max=%02x\n", max);
        return max;
}
EXPORT_SYMBOL_GPL(pci_scan_child_bus);

/**
 * pcibios_root_bridge_prepare - Platform-specific host bridge setup.
 * @bridge: Host bridge to set up.
 *
 * Default empty implementation.  Replace with an architecture-specific setup
 * routine, if necessary.
 */
int __weak pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
{
        return 0;
}

void __weak pcibios_add_bus(struct pci_bus *bus)
{
}

void __weak pcibios_remove_bus(struct pci_bus *bus)
{
}

struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
                struct pci_ops *ops, void *sysdata, struct list_head *resources)
{
        int error;
        struct pci_host_bridge *bridge;

        bridge = pci_alloc_host_bridge(0);
        if (!bridge)
                return NULL;

        bridge->dev.parent = parent;

        list_splice_init(resources, &bridge->windows);
        bridge->sysdata = sysdata;
        bridge->busnr = bus;
        bridge->ops = ops;

        error = pci_register_host_bridge(bridge);
        if (error < 0)
                goto err_out;

        return bridge->bus;

err_out:
        kfree(bridge);
        return NULL;
}
EXPORT_SYMBOL_GPL(pci_create_root_bus);

int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
{
        struct resource *res = &b->busn_res;
        struct resource *parent_res, *conflict;

        res->start = bus;
        res->end = bus_max;
        res->flags = IORESOURCE_BUS;

        if (!pci_is_root_bus(b))
                parent_res = &b->parent->busn_res;
        else {
                parent_res = get_pci_domain_busn_res(pci_domain_nr(b));
                res->flags |= IORESOURCE_PCI_FIXED;
        }

        conflict = request_resource_conflict(parent_res, res);

        if (conflict)
                dev_printk(KERN_DEBUG, &b->dev,
                           "busn_res: can not insert %pR under %s%pR (conflicts with %s %pR)\n",
                            res, pci_is_root_bus(b) ? "domain " : "",
                            parent_res, conflict->name, conflict);

        return conflict == NULL;
}

int pci_bus_update_busn_res_end(struct pci_bus *b, int bus_max)
{
        struct resource *res = &b->busn_res;
        struct resource old_res = *res;
        resource_size_t size;
        int ret;

        if (res->start > bus_max)
                return -EINVAL;

        size = bus_max - res->start + 1;
        ret = adjust_resource(res, res->start, size);
        dev_printk(KERN_DEBUG, &b->dev,
                        "busn_res: %pR end %s updated to %02x\n",
                        &old_res, ret ? "can not be" : "is", bus_max);

        if (!ret && !res->parent)
                pci_bus_insert_busn_res(b, res->start, res->end);

        return ret;
}

void pci_bus_release_busn_res(struct pci_bus *b)
{
        struct resource *res = &b->busn_res;
        int ret;

        if (!res->flags || !res->parent)
                return;

        ret = release_resource(res);
        dev_printk(KERN_DEBUG, &b->dev,
                        "busn_res: %pR %s released\n",
                        res, ret ? "can not be" : "is");
}

int pci_scan_root_bus_bridge(struct pci_host_bridge *bridge)
{
        struct resource_entry *window;
        bool found = false;
        struct pci_bus *b;
        int max, bus, ret;

        if (!bridge)
                return -EINVAL;

        resource_list_for_each_entry(window, &bridge->windows)
                if (window->res->flags & IORESOURCE_BUS) {
                        found = true;
                        break;
                }

        ret = pci_register_host_bridge(bridge);
        if (ret < 0)
                return ret;

        b = bridge->bus;
        bus = bridge->busnr;

        if (!found) {
                dev_info(&b->dev,
                 "No busn resource found for root bus, will use [bus %02x-ff]\n",
                        bus);
                pci_bus_insert_busn_res(b, bus, 255);
        }

        max = pci_scan_child_bus(b);

        if (!found)
                pci_bus_update_busn_res_end(b, max);

        return 0;
}
EXPORT_SYMBOL(pci_scan_root_bus_bridge);

struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
                struct pci_ops *ops, void *sysdata, struct list_head *resources)
{
        struct resource_entry *window;
        bool found = false;
        struct pci_bus *b;
        int max;

        resource_list_for_each_entry(window, resources)
                if (window->res->flags & IORESOURCE_BUS) {
                        found = true;
                        break;
                }

        b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
        if (!b)
                return NULL;

        if (!found) {
                dev_info(&b->dev,
                 "No busn resource found for root bus, will use [bus %02x-ff]\n",
                        bus);
                pci_bus_insert_busn_res(b, bus, 255);
        }

        max = pci_scan_child_bus(b);

        if (!found)
                pci_bus_update_busn_res_end(b, max);

        return b;
}
EXPORT_SYMBOL(pci_scan_root_bus);

struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
                                        void *sysdata)
{
        LIST_HEAD(resources);
        struct pci_bus *b;

        pci_add_resource(&resources, &ioport_resource);
        pci_add_resource(&resources, &iomem_resource);
        pci_add_resource(&resources, &busn_resource);
        b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
        if (b) {
                pci_scan_child_bus(b);
        } else {
                pci_free_resource_list(&resources);
        }
        return b;
}
EXPORT_SYMBOL(pci_scan_bus);

/**
 * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
 * @bridge: PCI bridge for the bus to scan
 *
 * Scan a PCI bus and child buses for new devices, add them,
 * and enable them, resizing bridge mmio/io resource if necessary
 * and possible.  The caller must ensure the child devices are already
 * removed for resizing to occur.
 *
 * Returns the max number of subordinate bus discovered.
 */
unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
{
        unsigned int max;
        struct pci_bus *bus = bridge->subordinate;

        max = pci_scan_child_bus(bus);

        pci_assign_unassigned_bridge_resources(bridge);

        pci_bus_add_devices(bus);

        return max;
}

/**
 * pci_rescan_bus - scan a PCI bus for devices.
 * @bus: PCI bus to scan
 *
 * Scan a PCI bus and child buses for new devices, adds them,
 * and enables them.
 *
 * Returns the max number of subordinate bus discovered.
 */
unsigned int pci_rescan_bus(struct pci_bus *bus)
{
        unsigned int max;

        max = pci_scan_child_bus(bus);
        pci_assign_unassigned_bus_resources(bus);
        pci_bus_add_devices(bus);

        return max;
}
EXPORT_SYMBOL_GPL(pci_rescan_bus);

/*
 * pci_rescan_bus(), pci_rescan_bus_bridge_resize() and PCI device removal
 * routines should always be executed under this mutex.
 */
static DEFINE_MUTEX(pci_rescan_remove_lock);

void pci_lock_rescan_remove(void)
{
        mutex_lock(&pci_rescan_remove_lock);
}
EXPORT_SYMBOL_GPL(pci_lock_rescan_remove);

void pci_unlock_rescan_remove(void)
{
        mutex_unlock(&pci_rescan_remove_lock);
}
EXPORT_SYMBOL_GPL(pci_unlock_rescan_remove);

static int __init pci_sort_bf_cmp(const struct device *d_a,
                                  const struct device *d_b)
{
        const struct pci_dev *a = to_pci_dev(d_a);
        const struct pci_dev *b = to_pci_dev(d_b);

        if      (pci_domain_nr(a->bus) < pci_domain_nr(b->bus)) return -1;
        else if (pci_domain_nr(a->bus) > pci_domain_nr(b->bus)) return  1;

        if      (a->bus->number < b->bus->number) return -1;
        else if (a->bus->number > b->bus->number) return  1;

        if      (a->devfn < b->devfn) return -1;
        else if (a->devfn > b->devfn) return  1;

        return 0;
}

void __init pci_sort_breadthfirst(void)
{
        bus_sort_breadthfirst(&pci_bus_type, &pci_sort_bf_cmp);
}