text: // SPDX-License-Identifier: GPL-2.0
  /*
   * PCI detection and setup code
   */
  
  #include <linux/kernel.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/pci.h>
  #include <linux/msi.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/aer.h>
  #include <linux/acpi.h>
  #include <linux/hypervisor.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;
  }
  
  /*
   * 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_next_device(&pci_bus_type, NULL);
  	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);
  
  	/*
  	 * base == maxbase can be valid only if the BAR has already been
  	 * programmed with all 1s.
  	 */
  	if (base == maxbase && ((base | (size - 1)) & 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) {
  		pci_info(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;
  			pci_err(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 - 1;
  			pci_info(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 - 1;
  
  	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;
  		pci_info(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)
  		pci_info(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;
  
  	/* Per PCIe r4.0, sec 9.3.4.1.11, the VF BARs are all RO Zero */
  	if (dev->is_virtfn)
  		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_windows(struct pci_dev *bridge)
  {
  	u16 io;
  	u32 pmem, tmp;
  
  	pci_read_config_word(bridge, PCI_IO_BASE, &io);
  	if (!io) {
  		pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0);
  		pci_read_config_word(bridge, PCI_IO_BASE, &io);
  		pci_write_config_word(bridge, PCI_IO_BASE, 0x0);
  	}
  	if (io)
  		bridge->io_window = 1;
  
  	/*
  	 * 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,
  					       0xffe0fff0);
  		pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem);
  		pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0);
  	}
  	if (!pmem)
  		return;
  
  	bridge->pref_window = 1;
  
  	if ((pmem & PCI_PREF_RANGE_TYPE_MASK) == PCI_PREF_RANGE_TYPE_64) {
  
  		/*
  		 * Bridge claims to have a 64-bit prefetchable memory
  		 * window; verify that the upper bits are actually
  		 * writable.
  		 */
  		pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &pmem);
  		pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32,
  				       0xffffffff);
  		pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp);
  		pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, pmem);
  		if (tmp)
  			bridge->pref_64_window = 1;
  	}
  }
  
  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);
  		pci_info(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);
  		pci_info(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) {
  		pci_err(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);
  		pci_info(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;
  
  	pci_info(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);
  				pci_info(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 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);
  
  	pci_free_resource_list(&bridge->windows);
  	pci_free_resource_list(&bridge->dma_ranges);
  	kfree(bridge);
  }
  
  static void pci_init_host_bridge(struct pci_host_bridge *bridge)
  {
  	INIT_LIST_HEAD(&bridge->windows);
  	INIT_LIST_HEAD(&bridge->dma_ranges);
  
  	/*
  	 * We assume we can manage these PCIe features.  Some systems may
  	 * reserve these for use by the platform itself, e.g., an ACPI BIOS
  	 * may implement its own AER handling and use _OSC to prevent the
  	 * OS from interfering.
  	 */
  	bridge->native_aer = 1;
  	bridge->native_pcie_hotplug = 1;
  	bridge->native_shpc_hotplug = 1;
  	bridge->native_pme = 1;
  	bridge->native_ltr = 1;
  	bridge->native_dpc = 1;
  
  	device_initialize(&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;
  
  	pci_init_host_bridge(bridge);
  	bridge->dev.release = pci_release_host_bridge_dev;
  
  	return bridge;
  }
  EXPORT_SYMBOL(pci_alloc_host_bridge);
  
  static void devm_pci_alloc_host_bridge_release(void *data)
  {
  	pci_free_host_bridge(data);
  }
  
  struct pci_host_bridge *devm_pci_alloc_host_bridge(struct device *dev,
  						   size_t priv)
  {
  	int ret;
  	struct pci_host_bridge *bridge;
  
  	bridge = pci_alloc_host_bridge(priv);
  	if (!bridge)
  		return NULL;
  
  	bridge->dev.parent = dev;
  
  	ret = devm_add_action_or_reset(dev, devm_pci_alloc_host_bridge_release,
  				       bridge);
  	if (ret)
  		return NULL;
  
  	ret = devm_of_pci_bridge_init(dev, bridge);
  	if (ret)
  		return NULL;
  
  	return bridge;
  }
  EXPORT_SYMBOL(devm_pci_alloc_host_bridge);
  
  void pci_free_host_bridge(struct pci_host_bridge *bridge)
  {
  	put_device(&bridge->dev);
  }
  EXPORT_SYMBOL(pci_free_host_bridge);
  
  /* Indexed by PCI_X_SSTATUS_FREQ (secondary bus mode and frequency) */
  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 */
  };
  
  /* Indexed by PCI_EXP_LNKCAP_SLS, PCI_EXP_LNKSTA_CLS */
  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 */
  	PCIE_SPEED_16_0GT,		/* 4 */
  	PCIE_SPEED_32_0GT,		/* 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 */
  };
  EXPORT_SYMBOL_GPL(pcie_link_speed);
  
  const char *pci_speed_string(enum pci_bus_speed speed)
  {
  	/* Indexed by the pci_bus_speed enum */
  	static const char *speed_strings[] = {
  	    "33 MHz PCI",		/* 0x00 */
  	    "66 MHz PCI",		/* 0x01 */
  	    "66 MHz PCI-X",		/* 0x02 */
  	    "100 MHz PCI-X",		/* 0x03 */
  	    "133 MHz PCI-X",		/* 0x04 */
  	    NULL,			/* 0x05 */
  	    NULL,			/* 0x06 */
  	    NULL,			/* 0x07 */
  	    NULL,			/* 0x08 */
  	    "66 MHz PCI-X 266",		/* 0x09 */
  	    "100 MHz PCI-X 266",	/* 0x0a */
  	    "133 MHz PCI-X 266",	/* 0x0b */
  	    "Unknown AGP",		/* 0x0c */
  	    "1x AGP",			/* 0x0d */
  	    "2x AGP",			/* 0x0e */
  	    "4x AGP",			/* 0x0f */
  	    "8x AGP",			/* 0x10 */
  	    "66 MHz PCI-X 533",		/* 0x11 */
  	    "100 MHz PCI-X 533",	/* 0x12 */
  	    "133 MHz PCI-X 533",	/* 0x13 */
  	    "2.5 GT/s PCIe",		/* 0x14 */
  	    "5.0 GT/s PCIe",		/* 0x15 */
  	    "8.0 GT/s PCIe",		/* 0x16 */
  	    "16.0 GT/s PCIe",		/* 0x17 */
  	    "32.0 GT/s PCIe",		/* 0x18 */
  	};
  
  	if (speed < ARRAY_SIZE(speed_strings))
  		return speed_strings[speed];
  	return "Unknown";
  }
  EXPORT_SYMBOL_GPL(pci_speed_string);
  
  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];
  		bridge->link_active_reporting = !!(linkcap & PCI_EXP_LNKCAP_DLLLARC);
  
  		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->backup_ops = bus->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) {
  		/* Ignore it if we already got here via a different bridge */
  		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_add(&bridge->dev);
  	if (err) {
  		put_device(&bridge->dev);
  		goto free;
  	}
  	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);
  
  	if (bus->ops->add_bus) {
  		err = bus->ops->add_bus(bus);
  		if (WARN_ON(err < 0))
  			dev_err(&bus->dev, "failed to add bus: %d\n", err);
  	}
  
  	/* 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);
  
  	if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
  		dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");
  
  	/* 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_del(&bridge->dev);
  
  free:
  	kfree(bus);
  	return err;
  }
  
  static bool pci_bridge_child_ext_cfg_accessible(struct pci_dev *bridge)
  {
  	int pos;
  	u32 status;
  
  	/*
  	 * If extended config space isn't accessible on a bridge's primary
  	 * bus, we certainly can't access it on the secondary bus.
  	 */
  	if (bridge->bus->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG)
  		return false;
  
  	/*
  	 * PCIe Root Ports and switch ports are PCIe on both sides, so if
  	 * extended config space is accessible on the primary, it's also
  	 * accessible on the secondary.
  	 */
  	if (pci_is_pcie(bridge) &&
  	    (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT ||
  	     pci_pcie_type(bridge) == PCI_EXP_TYPE_UPSTREAM ||
  	     pci_pcie_type(bridge) == PCI_EXP_TYPE_DOWNSTREAM))
  		return true;
  
  	/*
  	 * For the other bridge types:
  	 *   - PCI-to-PCI bridges
  	 *   - PCIe-to-PCI/PCI-X forward bridges
  	 *   - PCI/PCI-X-to-PCIe reverse bridges
  	 * extended config space on the secondary side is only accessible
  	 * if the bridge supports PCI-X Mode 2.
  	 */
  	pos = pci_find_capability(bridge, PCI_CAP_ID_PCIX);
  	if (!pos)
  		return false;
  
  	pci_read_config_dword(bridge, pos + PCI_X_STATUS, &status);
  	return status & (PCI_X_STATUS_266MHZ | PCI_X_STATUS_533MHZ);
  }
  
  static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
  					   struct pci_dev *bridge, int busnr)
  {
  	struct pci_bus *child;
  	struct pci_host_bridge *host;
  	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->msi = parent->msi;
  	child->sysdata = parent->sysdata;
  	child->bus_flags = parent->bus_flags;
  
  	host = pci_find_host_bridge(parent);
  	if (host->child_ops) {
  		child->ops = host->child_ops;
  	} else {
  		if (parent->backup_ops)
  			child->ops = parent->backup_ops;
  		else
  			child->ops = parent->ops;
  	}
  	child->backup_ops = child->ops;
  
  	/*
  	 * 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);
  
  	/*
  	 * Check whether extended config space is accessible on the child
  	 * bus.  Note that we currently assume it is always accessible on
  	 * the root bus.
  	 */
  	if (!pci_bridge_child_ext_cfg_accessible(bridge)) {
  		child->bus_flags |= PCI_BUS_FLAGS_NO_EXTCFG;
  		pci_info(child, "extended config space not accessible\n");
  	}
  
  	/* 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);
  }
  
  static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
  					      unsigned int available_buses);
  /**
   * pci_ea_fixed_busnrs() - Read fixed Secondary and Subordinate bus
   * numbers from EA capability.
   * @dev: Bridge
   * @sec: updated with secondary bus number from EA
   * @sub: updated with subordinate bus number from EA
   *
   * If @dev is a bridge with EA capability that specifies valid secondary
   * and subordinate bus numbers, return true with the bus numbers in @sec
   * and @sub.  Otherwise return false.
   */
  static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub)
  {
  	int ea, offset;
  	u32 dw;
  	u8 ea_sec, ea_sub;
  
  	if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
  		return false;
  
  	/* find PCI EA capability in list */
  	ea = pci_find_capability(dev, PCI_CAP_ID_EA);
  	if (!ea)
  		return false;
  
  	offset = ea + PCI_EA_FIRST_ENT;
  	pci_read_config_dword(dev, offset, &dw);
  	ea_sec =  dw & PCI_EA_SEC_BUS_MASK;
  	ea_sub = (dw & PCI_EA_SUB_BUS_MASK) >> PCI_EA_SUB_BUS_SHIFT;
  	if (ea_sec  == 0 || ea_sub < ea_sec)
  		return false;
  
  	*sec = ea_sec;
  	*sub = ea_sub;
  	return true;
  }
  
  /*
   * pci_scan_bridge_extend() - Scan buses behind a bridge
   * @bus: Parent bus the bridge is on
   * @dev: Bridge itself
   * @max: Starting subordinate number of buses behind this bridge
   * @available_buses: Total number of buses available for this bridge and
   *		     the devices below. After the minimal bus space has
   *		     been allocated the remaining buses will be
   *		     distributed equally between hotplug-capable bridges.
   * @pass: Either %0 (scan already configured bridges) or %1 (scan bridges
   *        that need to be reconfigured.
   *
   * 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.
   *
   * Return: New subordinate number covering all buses behind this bridge.
   */
  static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
  				  int max, unsigned int available_buses,
  				  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;
  	bool fixed_buses;
  	u8 fixed_sec, fixed_sub;
  	int next_busnr;
  
  	/*
  	 * 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;
  
  	pci_dbg(dev, "scanning [bus %02x-%02x] behind bridge, pass %d\n",
  		secondary, subordinate, pass);
  
  	if (!primary && (primary != bus->number) && secondary && subordinate) {
  		pci_warn(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)) {
  		pci_info(dev, "bridge configuration invalid ([bus %02x-%02x]), reconfiguring\n",
  			 secondary, subordinate);
  		broken = 1;
  	}
  
  	/*
  	 * Disable Master-Abort Mode 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)
  			pci_warn(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);
  
  		/* Read bus numbers from EA Capability (if present) */
  		fixed_buses = pci_ea_fixed_busnrs(dev, &fixed_sec, &fixed_sub);
  		if (fixed_buses)
  			next_busnr = fixed_sec;
  		else
  			next_busnr = max + 1;
  
  		/*
  		 * 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), next_busnr);
  		if (!child) {
  			child = pci_add_new_bus(bus, dev, next_busnr);
  			if (!child)
  				goto out;
  			pci_bus_insert_busn_res(child, next_busnr,
  						bus->busn_res.end);
  		}
  		max++;
  		if (available_buses)
  			available_buses--;
  
  		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_extend(child, available_buses);
  		} 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 subordinate bus number to its real value.
  		 * If fixed subordinate bus number exists from EA
  		 * capability then use it.
  		 */
  		if (fixed_buses)
  			max = fixed_sub;
  		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);
  
  	/* Check that all devices are accessible */
  	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(&dev->dev, "devices behind bridge are unusable because %pR cannot be assigned for them\n",
  				 &child->busn_res);
  			break;
  		}
  		bus = bus->parent;
  	}
  
  out:
  	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
  
  	pm_runtime_put(&dev->dev);
  
  	return max;
  }
  
  /*
   * pci_scan_bridge() - Scan buses behind a bridge
   * @bus: Parent bus the bridge is on
   * @dev: Bridge itself
   * @max: Starting subordinate number of buses behind this bridge
   * @pass: Either %0 (scan already configured bridges) or %1 (scan bridges
   *        that need to be reconfigured.
   *
   * 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.
   *
   * Return: New subordinate number covering all buses behind this bridge.
   */
  int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
  {
  	return pci_scan_bridge_extend(bus, dev, max, 0, pass);
  }
  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;
  
  	/* VFs are not allowed to use INTx, so skip the config reads */
  	if (dev->is_virtfn) {
  		dev->pin = 0;
  		dev->irq = 0;
  		return;
  	}
  
  	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;
  
  	parent = pci_upstream_bridge(pdev);
  	if (!parent)
  		return;
  
  	/*
  	 * Some systems do not identify their upstream/downstream ports
  	 * correctly so detect impossible configurations here and correct
  	 * the port type accordingly.
  	 */
  	type = pci_pcie_type(pdev);
  	if (type == PCI_EXP_TYPE_DOWNSTREAM) {
  		/*
  		 * If pdev claims to be downstream port but the parent
  		 * device is also downstream port assume pdev is actually
  		 * upstream port.
  		 */
  		if (pcie_downstream_port(parent)) {
  			pci_info(pdev, "claims to be downstream port but is acting as upstream port, correcting type\n");
  			pdev->pcie_flags_reg &= ~PCI_EXP_FLAGS_TYPE;
  			pdev->pcie_flags_reg |= PCI_EXP_TYPE_UPSTREAM;
  		}
  	} else if (type == PCI_EXP_TYPE_UPSTREAM) {
  		/*
  		 * If pdev claims to be upstream port but the parent
  		 * device is also upstream port assume pdev is actually
  		 * downstream port.
  		 */
  		if (pci_pcie_type(parent) == PCI_EXP_TYPE_UPSTREAM) {
  			pci_info(pdev, "claims to be upstream port but is acting as downstream port, correcting type\n");
  			pdev->pcie_flags_reg &= ~PCI_EXP_FLAGS_TYPE;
  			pdev->pcie_flags_reg |= PCI_EXP_TYPE_DOWNSTREAM;
  		}
  	}
  }
  
  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;
  		}
  	}
  }
  
  static void set_pcie_untrusted(struct pci_dev *dev)
  {
  	struct pci_dev *parent;
  
  	/*
  	 * If the upstream bridge is untrusted we treat this device
  	 * untrusted as well.
  	 */
  	parent = pci_upstream_bridge(dev);
  	if (parent && (parent->untrusted || parent->external_facing))
  		dev->untrusted = true;
  }
  
  /**
   * 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;
  
  #ifdef CONFIG_PCI_IOV
  	/*
  	 * Per the SR-IOV specification (rev 1.1, sec 3.5), VFs are required to
  	 * implement a PCIe capability and therefore must implement extended
  	 * config space.  We can skip the NO_EXTCFG test below and the
  	 * reachability/aliasing test in pci_cfg_space_size_ext() by virtue of
  	 * the fact that the SR-IOV capability on the PF resides in extended
  	 * config space and must be accessible and non-aliased to have enabled
  	 * support for this VF.  This is a micro performance optimization for
  	 * systems supporting many VFs.
  	 */
  	if (dev->is_virtfn)
  		return PCI_CFG_SPACE_EXP_SIZE;
  #endif
  
  	if (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG)
  		return PCI_CFG_SPACE_SIZE;
  
  	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;
  }
  
  static u32 pci_class(struct pci_dev *dev)
  {
  	u32 class;
  
  #ifdef CONFIG_PCI_IOV
  	if (dev->is_virtfn)
  		return dev->physfn->sriov->class;
  #endif
  	pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
  	return class;
  }
  
  static void pci_subsystem_ids(struct pci_dev *dev, u16 *vendor, u16 *device)
  {
  #ifdef CONFIG_PCI_IOV
  	if (dev->is_virtfn) {
  		*vendor = dev->physfn->sriov->subsystem_vendor;
  		*device = dev->physfn->sriov->subsystem_device;
  		return;
  	}
  #endif
  	pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, vendor);
  	pci_read_config_word(dev, PCI_SUBSYSTEM_ID, device);
  }
  
  static u8 pci_hdr_type(struct pci_dev *dev)
  {
  	u8 hdr_type;
  
  #ifdef CONFIG_PCI_IOV
  	if (dev->is_virtfn)
  		return dev->physfn->sriov->hdr_type;
  #endif
  	pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type);
  	return hdr_type;
  }
  
  #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;
  }
  
  static void early_dump_pci_device(struct pci_dev *pdev)
  {
  	u32 value[256 / 4];
  	int i;
  
  	pci_info(pdev, "config space:\n");
  
  	for (i = 0; i < 256; i += 4)
  		pci_read_config_dword(pdev, i, &value[i / 4]);
  
  	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 1,
  		       value, 256, false);
  }
  
  /**
   * 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;
  
  	hdr_type = pci_hdr_type(dev);
  
  	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));
  
  	class = pci_class(dev);
  
  	dev->revision = class & 0xff;
  	dev->class = class >> 8;		    /* upper 3 bytes */
  
  	if (pci_early_dump)
  		early_dump_pci_device(dev);
  
  	/* 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);
  
  	set_pcie_untrusted(dev);
  
  	/* "Unknown power state" */
  	dev->current_state = PCI_UNKNOWN;
  
  	/* Early fixups, before probing the BARs */
  	pci_fixup_device(pci_fixup_early, dev);
  
  	pci_info(dev, "[%04x:%04x] type %02x class %#08x\n",
  		 dev->vendor, dev->device, dev->hdr_type, dev->class);
  
  	/* Device class may be changed after fixup */
  	class = dev->class >> 8;
  
  	if (dev->non_compliant_bars && !dev->mmio_always_on) {
  		pci_read_config_word(dev, PCI_COMMAND, &cmd);
  		if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
  			pci_info(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_subsystem_ids(dev, &dev->subsystem_vendor, &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);
  				pci_info(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);
  				pci_info(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);
  				pci_info(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);
  				pci_info(dev, "legacy IDE quirk: reg 0x1c: %pR\n",
  					 res);
  			}
  		}
  		break;
  
  	case PCI_HEADER_TYPE_BRIDGE:		    /* bridge header */
  		/*
  		 * 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);
  		pci_read_bridge_windows(dev);
  		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 */
  		pci_err(dev, "unknown header type %02x, ignoring device\n",
  			dev->hdr_type);
  		return -EIO;
  
  	bad:
  		pci_err(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, mpss, p_mps, rc;
  
  	if (!pci_is_pcie(dev))
  		return;
  
  	/* MPS and MRRS fields are of type 'RsvdP' for VFs, short-circuit out */
  	if (dev->is_virtfn)
  		return;
  
  	/*
  	 * For Root Complex Integrated Endpoints, program the maximum
  	 * supported value unless limited by the PCIE_BUS_PEER2PEER case.
  	 */
  	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {
  		if (pcie_bus_config == PCIE_BUS_PEER2PEER)
  			mps = 128;
  		else
  			mps = 128 << dev->pcie_mpss;
  		rc = pcie_set_mps(dev, mps);
  		if (rc) {
  			pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n",
  				 mps);
  		}
  		return;
  	}
  
  	if (!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) {
  		pci_warn(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;
  
  	mpss = 128 << dev->pcie_mpss;
  	if (mpss < p_mps && pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT) {
  		pcie_set_mps(bridge, mpss);
  		pci_info(dev, "Upstream bridge's Max Payload Size set to %d (was %d, max %d)\n",
  			 mpss, p_mps, 128 << bridge->pcie_mpss);
  		p_mps = pcie_get_mps(bridge);
  	}
  
  	rc = pcie_set_mps(dev, p_mps);
  	if (rc) {
  		pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n",
  			 p_mps);
  		return;
  	}
  
  	pci_info(dev, "Max Payload Size set to %d (was %d, max %d)\n",
  		 p_mps, mps, mpss);
  }
  
  int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
  {
  	struct pci_host_bridge *host;
  	u32 cap;
  	u16 ctl;
  	int ret;
  
  	if (!pci_is_pcie(dev))
  		return 0;
  
  	ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
  	if (ret)
  		return 0;
  
  	if (!(cap & PCI_EXP_DEVCAP_EXT_TAG))
  		return 0;
  
  	ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
  	if (ret)
  		return 0;
  
  	host = pci_find_host_bridge(dev->bus);
  	if (!host)
  		return 0;
  
  	/*
  	 * If some device in the hierarchy doesn't handle Extended Tags
  	 * correctly, make sure they're disabled.
  	 */
  	if (host->no_ext_tags) {
  		if (ctl & PCI_EXP_DEVCTL_EXT_TAG) {
  			pci_info(dev, "disabling Extended Tags\n");
  			pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
  						   PCI_EXP_DEVCTL_EXT_TAG);
  		}
  		return 0;
  	}
  
  	if (!(ctl & PCI_EXP_DEVCTL_EXT_TAG)) {
  		pci_info(dev, "enabling Extended Tags\n");
  		pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
  					 PCI_EXP_DEVCTL_EXT_TAG);
  	}
  	return 0;
  }
  
  /**
   * pcie_relaxed_ordering_enabled - Probe for PCIe relaxed ordering enable
   * @dev: PCI device to query
   *
   * Returns true if the device has enabled relaxed ordering attribute.
   */
  bool pcie_relaxed_ordering_enabled(struct pci_dev *dev)
  {
  	u16 v;
  
  	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);
  
  	return !!(v & PCI_EXP_DEVCTL_RELAX_EN);
  }
  EXPORT_SYMBOL(pcie_relaxed_ordering_enabled);
  
  static void pci_configure_relaxed_ordering(struct pci_dev *dev)
  {
  	struct pci_dev *root;
  
  	/* PCI_EXP_DEVICE_RELAX_EN is RsvdP in VFs */
  	if (dev->is_virtfn)
  		return;
  
  	if (!pcie_relaxed_ordering_enabled(dev))
  		return;
  
  	/*
  	 * For now, we only deal with Relaxed Ordering issues with Root
  	 * Ports. Peer-to-Peer DMA is another can of worms.
  	 */
  	root = pcie_find_root_port(dev);
  	if (!root)
  		return;
  
  	if (root->dev_flags & PCI_DEV_FLAGS_NO_RELAXED_ORDERING) {
  		pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
  					   PCI_EXP_DEVCTL_RELAX_EN);
  		pci_info(dev, "Relaxed Ordering disabled because the Root Port didn't support it\n");
  	}
  }
  
  static void pci_configure_ltr(struct pci_dev *dev)
  {
  #ifdef CONFIG_PCIEASPM
  	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
  	struct pci_dev *bridge;
  	u32 cap, ctl;
  
  	if (!pci_is_pcie(dev))
  		return;
  
  	/* Read L1 PM substate capabilities */
  	dev->l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
  
  	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
  	if (!(cap & PCI_EXP_DEVCAP2_LTR))
  		return;
  
  	pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl);
  	if (ctl & PCI_EXP_DEVCTL2_LTR_EN) {
  		if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
  			dev->ltr_path = 1;
  			return;
  		}
  
  		bridge = pci_upstream_bridge(dev);
  		if (bridge && bridge->ltr_path)
  			dev->ltr_path = 1;
  
  		return;
  	}
  
  	if (!host->native_ltr)
  		return;
  
  	/*
  	 * Software must not enable LTR in an Endpoint unless the Root
  	 * Complex and all intermediate Switches indicate support for LTR.
  	 * PCIe r4.0, sec 6.18.
  	 */
  	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
  	    ((bridge = pci_upstream_bridge(dev)) &&
  	      bridge->ltr_path)) {
  		pcie_capability_set_word(dev, PCI_EXP_DEVCTL2,
  					 PCI_EXP_DEVCTL2_LTR_EN);
  		dev->ltr_path = 1;
  	}
  #endif
  }
  
  static void pci_configure_eetlp_prefix(struct pci_dev *dev)
  {
  #ifdef CONFIG_PCI_PASID
  	struct pci_dev *bridge;
  	int pcie_type;
  	u32 cap;
  
  	if (!pci_is_pcie(dev))
  		return;
  
  	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
  	if (!(cap & PCI_EXP_DEVCAP2_EE_PREFIX))
  		return;
  
  	pcie_type = pci_pcie_type(dev);
  	if (pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
  	    pcie_type == PCI_EXP_TYPE_RC_END)
  		dev->eetlp_prefix_path = 1;
  	else {
  		bridge = pci_upstream_bridge(dev);
  		if (bridge && bridge->eetlp_prefix_path)
  			dev->eetlp_prefix_path = 1;
  	}
  #endif
  }
  
  static void pci_configure_serr(struct pci_dev *dev)
  {
  	u16 control;
  
  	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
  
  		/*
  		 * A bridge will not forward ERR_ messages coming from an
  		 * endpoint unless SERR# forwarding is enabled.
  		 */
  		pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
  		if (!(control & PCI_BRIDGE_CTL_SERR)) {
  			control |= PCI_BRIDGE_CTL_SERR;
  			pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
  		}
  	}
  }
  
  static void pci_configure_device(struct pci_dev *dev)
  {
  	pci_configure_mps(dev);
  	pci_configure_extended_tags(dev, NULL);
  	pci_configure_relaxed_ordering(dev);
  	pci_configure_ltr(dev);
  	pci_configure_eetlp_prefix(dev);
  	pci_configure_serr(dev);
  
  	pci_acpi_program_hp_params(dev);
  }
  
  static void pci_release_capabilities(struct pci_dev *dev)
  {
  	pci_aer_exit(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);
  	bitmap_free(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);
  
  static bool pci_bus_crs_vendor_id(u32 l)
  {
  	return (l & 0xffff) == 0x0001;
  }
  
  static bool pci_bus_wait_crs(struct pci_bus *bus, int devfn, u32 *l,
  			     int timeout)
  {
  	int delay = 1;
  
  	if (!pci_bus_crs_vendor_id(*l))
  		return true;	/* not a CRS completion */
  
  	if (!timeout)
  		return false;	/* CRS, but caller doesn't want to wait */
  
  	/*
  	 * We got the reserved Vendor ID that indicates a completion with
  	 * Configuration Request Retry Status (CRS).  Retry until we get a
  	 * valid Vendor ID or we time out.
  	 */
  	while (pci_bus_crs_vendor_id(*l)) {
  		if (delay > timeout) {
  			pr_warn("pci %04x:%02x:%02x.%d: not ready after %dms; giving up\n",
  				pci_domain_nr(bus), bus->number,
  				PCI_SLOT(devfn), PCI_FUNC(devfn), delay - 1);
  
  			return false;
  		}
  		if (delay >= 1000)
  			pr_info("pci %04x:%02x:%02x.%d: not ready after %dms; waiting\n",
  				pci_domain_nr(bus), bus->number,
  				PCI_SLOT(devfn), PCI_FUNC(devfn), delay - 1);
  
  		msleep(delay);
  		delay *= 2;
  
  		if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
  			return false;
  	}
  
  	if (delay >= 1000)
  		pr_info("pci %04x:%02x:%02x.%d: ready after %dms\n",
  			pci_domain_nr(bus), bus->number,
  			PCI_SLOT(devfn), PCI_FUNC(devfn), delay - 1);
  
  	return true;
  }
  
  bool pci_bus_generic_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
  					int timeout)
  {
  	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;
  
  	if (pci_bus_crs_vendor_id(*l))
  		return pci_bus_wait_crs(bus, devfn, l, timeout);
  
  	return true;
  }
  
  bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
  				int timeout)
  {
  #ifdef CONFIG_PCI_QUIRKS
  	struct pci_dev *bridge = bus->self;
  
  	/*
  	 * Certain IDT switches have an issue where they improperly trigger
  	 * ACS Source Validation errors on completions for config reads.
  	 */
  	if (bridge && bridge->vendor == PCI_VENDOR_ID_IDT &&
  	    bridge->device == 0x80b5)
  		return pci_idt_bus_quirk(bus, devfn, l, timeout);
  #endif
  
  	return pci_bus_generic_read_dev_vendor_id(bus, devfn, l, timeout);
  }
  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;
  }
  
  void pcie_report_downtraining(struct pci_dev *dev)
  {
  	if (!pci_is_pcie(dev))
  		return;
  
  	/* Look from the device up to avoid downstream ports with no devices */
  	if ((pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT) &&
  	    (pci_pcie_type(dev) != PCI_EXP_TYPE_LEG_END) &&
  	    (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM))
  		return;
  
  	/* Multi-function PCIe devices share the same link/status */
  	if (PCI_FUNC(dev->devfn) != 0 || dev->is_virtfn)
  		return;
  
  	/* Print link status only if the device is constrained by the fabric */
  	__pcie_print_link_status(dev, false);
  }
  
  static void pci_init_capabilities(struct pci_dev *dev)
  {
  	pci_ea_init(dev);		/* Enhanced Allocation */
  
  	/* 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);
  
  	pci_pm_init(dev);		/* Power Management */
  	pci_vpd_init(dev);		/* Vital Product Data */
  	pci_configure_ari(dev);		/* Alternative Routing-ID Forwarding */
  	pci_iov_init(dev);		/* Single Root I/O Virtualization */
  	pci_ats_init(dev);		/* Address Translation Services */
  	pci_pri_init(dev);		/* Page Request Interface */
  	pci_pasid_init(dev);		/* Process Address Space ID */
  	pci_acs_init(dev);		/* Access Control Services */
  	pci_ptm_init(dev);		/* Precision Time Measurement */
  	pci_aer_init(dev);		/* Advanced Error Reporting */
  	pci_dpc_init(dev);		/* Downstream Port Containment */
  
  	pcie_report_downtraining(dev);
  
  	if (pci_probe_reset_function(dev) == 0)
  		dev->reset_fn = 1;
  }
  
  /*
   * 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;
  
  	dma_set_max_seg_size(&dev->dev, 65536);
  	dma_set_seg_boundary(&dev->dev, 0xffffffff);
  
  	/* Fix up broken headers */
  	pci_fixup_device(pci_fixup_header, dev);
  
  	pci_reassigndev_resource_alignment(dev);
  
  	dev->state_saved = false;
  
  	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);
  
  	/* Set up 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 *bridge = bus->self;
  
  	/*
  	 * Systems with unusual topologies set PCI_SCAN_ALL_PCIE_DEVS so
  	 * we scan for all possible devices, not just Device 0.
  	 */
  	if (pci_has_flag(PCI_SCAN_ALL_PCIE_DEVS))
  		return 0;
  
  	/*
  	 * A PCIe Downstream Port normally leads to a Link with only Device
  	 * 0 on it (PCIe spec r3.1, sec 7.3.1).  As an optimization, scan
  	 * only for Device 0 in that situation.
  	 */
  	if (bridge && pci_is_pcie(bridge) && pcie_downstream_port(bridge))
  		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 (!pci_dev_is_added(dev))
  		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 (!pci_dev_is_added(dev))
  				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)
  		pci_err(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;
  
  		pci_warn(dev, "Failed attempting to set the MRRS\n");
  		mrrs /= 2;
  	}
  
  	if (mrrs < 128)
  		pci_err(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);
  
  	pci_info(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);
  
  /*
   * Called after each bus is probed, but before its children are examined.  This
   * is marked as __weak because multiple architectures define it.
   */
  void __weak pcibios_fixup_bus(struct pci_bus *bus)
  {
         /* nothing to do, expected to be removed in the future */
  }
  
  /**
   * pci_scan_child_bus_extend() - Scan devices below a bus
   * @bus: Bus to scan for devices
   * @available_buses: Total number of buses available (%0 does not try to
   *		     extend beyond the minimal)
   *
   * Scans devices below @bus including subordinate buses. Returns new
   * subordinate number including all the found devices. Passing
   * @available_buses causes the remaining bus space to be distributed
   * equally between hotplug-capable bridges to allow future extension of the
   * hierarchy.
   */
  static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
  					      unsigned int available_buses)
  {
  	unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;
  	unsigned int start = bus->busn_res.start;
  	unsigned int devfn, fn, cmax, max = start;
  	struct pci_dev *dev;
  	int nr_devs;
  
  	dev_dbg(&bus->dev, "scanning bus\n");
  
  	/* Go find them, Rover! */
  	for (devfn = 0; devfn < 256; devfn += 8) {
  		nr_devs = pci_scan_slot(bus, devfn);
  
  		/*
  		 * The Jailhouse hypervisor may pass individual functions of a
  		 * multi-function device to a guest without passing function 0.
  		 * Look for them as well.
  		 */
  		if (jailhouse_paravirt() && nr_devs == 0) {
  			for (fn = 1; fn < 8; fn++) {
  				dev = pci_scan_single_device(bus, devfn + fn);
  				if (dev)
  					dev->multifunction = 1;
  			}
  		}
  	}
  
  	/* Reserve buses for SR-IOV capability */
  	used_buses = pci_iov_bus_range(bus);
  	max += used_buses;
  
  	/*
  	 * 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;
  	}
  
  	/*
  	 * Calculate how many hotplug bridges and normal bridges there
  	 * are on this bus. We will distribute the additional available
  	 * buses between hotplug bridges.
  	 */
  	for_each_pci_bridge(dev, bus) {
  		if (dev->is_hotplug_bridge)
  			hotplug_bridges++;
  		else
  			normal_bridges++;
  	}
  
  	/*
  	 * Scan bridges that are already configured. We don't touch them
  	 * unless they are misconfigured (which will be done in the second
  	 * scan below).
  	 */
  	for_each_pci_bridge(dev, bus) {
  		cmax = max;
  		max = pci_scan_bridge_extend(bus, dev, max, 0, 0);
  
  		/*
  		 * Reserve one bus for each bridge now to avoid extending
  		 * hotplug bridges too much during the second scan below.
  		 */
  		used_buses++;
  		if (cmax - max > 1)
  			used_buses += cmax - max - 1;
  	}
  
  	/* Scan bridges that need to be reconfigured */
  	for_each_pci_bridge(dev, bus) {
  		unsigned int buses = 0;
  
  		if (!hotplug_bridges && normal_bridges == 1) {
  
  			/*
  			 * There is only one bridge on the bus (upstream
  			 * port) so it gets all available buses which it
  			 * can then distribute to the possible hotplug
  			 * bridges below.
  			 */
  			buses = available_buses;
  		} else if (dev->is_hotplug_bridge) {
  
  			/*
  			 * Distribute the extra buses between hotplug
  			 * bridges if any.
  			 */
  			buses = available_buses / hotplug_bridges;
  			buses = min(buses, available_buses - used_buses + 1);
  		}
  
  		cmax = max;
  		max = pci_scan_bridge_extend(bus, dev, cmax, buses, 1);
  		/* One bus is already accounted so don't add it again */
  		if (max - cmax > 1)
  			used_buses += max - cmax - 1;
  	}
  
  	/*
  	 * Make sure a hotplug bridge has at least the minimum requested
  	 * number of buses but allow it to grow up to the maximum available
  	 * bus number of there is room.
  	 */
  	if (bus->self && bus->self->is_hotplug_bridge) {
  		used_buses = max_t(unsigned int, available_buses,
  				   pci_hotplug_bus_size - 1);
  		if (max - start < used_buses) {
  			max = start + used_buses;
  
  			/* Do not allocate more buses than we have room left */
  			if (max > bus->busn_res.end)
  				max = bus->busn_res.end;
  
  			dev_dbg(&bus->dev, "%pR extended by %#02x\n",
  				&bus->busn_res, max - start);
  		}
  	}
  
  	/*
  	 * 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;
  }
  
  /**
   * pci_scan_child_bus() - Scan devices below a bus
   * @bus: Bus to scan for devices
   *
   * Scans devices below @bus including subordinate buses. Returns new
   * subordinate number including all the found devices.
   */
  unsigned int pci_scan_child_bus(struct pci_bus *bus)
  {
  	return pci_scan_child_bus_extend(bus, 0);
  }
  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:
  	put_device(&bridge->dev);
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(pci_create_root_bus);
  
  int pci_host_probe(struct pci_host_bridge *bridge)
  {
  	struct pci_bus *bus, *child;
  	int ret;
  
  	ret = pci_scan_root_bus_bridge(bridge);
  	if (ret < 0) {
  		dev_err(bridge->dev.parent, "Scanning root bridge failed");
  		return ret;
  	}
  
  	bus = bridge->bus;
  
  	/*
  	 * We insert PCI resources into the iomem_resource and
  	 * ioport_resource trees in either pci_bus_claim_resources()
  	 * or pci_bus_assign_resources().
  	 */
  	if (pci_has_flag(PCI_PROBE_ONLY)) {
  		pci_bus_claim_resources(bus);
  	} else {
  		pci_bus_size_bridges(bus);
  		pci_bus_assign_resources(bus);
  
  		list_for_each_entry(child, &bus->children, node)
  			pcie_bus_configure_settings(child);
  	}
  
  	pci_bus_add_devices(bus);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_host_probe);
  
  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_info(&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_info(&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_info(&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) {
  			bridge->busnr = window->res->start;
  			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, add them,
   * and enable 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);
  }
  
  int pci_hp_add_bridge(struct pci_dev *dev)
  {
  	struct pci_bus *parent = dev->bus;
  	int busnr, start = parent->busn_res.start;
  	unsigned int available_buses = 0;
  	int end = parent->busn_res.end;
  
  	for (busnr = start; busnr <= end; busnr++) {
  		if (!pci_find_bus(pci_domain_nr(parent), busnr))
  			break;
  	}
  	if (busnr-- > end) {
  		pci_err(dev, "No bus number available for hot-added bridge\n");
  		return -1;
  	}
  
  	/* Scan bridges that are already configured */
  	busnr = pci_scan_bridge(parent, dev, busnr, 0);
  
  	/*
  	 * Distribute the available bus numbers between hotplug-capable
  	 * bridges to make extending the chain later possible.
  	 */
  	available_buses = end - busnr;
  
  	/* Scan bridges that need to be reconfigured */
  	pci_scan_bridge_extend(parent, dev, busnr, available_buses, 1);
  
  	if (!dev->subordinate)
  		return -1;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_hp_add_bridge);
  