drivers/pci/search.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * PCI searching functions
  *
  * Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
  *					David Mosberger-Tang
  * Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
  * Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
  */

 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include "pci.h"

 DECLARE_RWSEM(pci_bus_sem);
 EXPORT_SYMBOL_GPL(pci_bus_sem);

 /*
  * pci_for_each_dma_alias - Iterate over DMA aliases for a device
  * @pdev: starting downstream device
  * @fn: function to call for each alias
  * @data: opaque data to pass to @fn
  *
  * Starting @pdev, walk up the bus calling @fn for each possible alias
  * of @pdev at the root bus.
  */
 int pci_for_each_dma_alias(struct pci_dev *pdev,
 			   int (*fn)(struct pci_dev *pdev,
 				     u16 alias, void *data), void *data)
 {
 	struct pci_bus *bus;
 	int ret;

 	ret = fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn), data);
 	if (ret)
 		return ret;

 	/*
 	 * If the device is broken and uses an alias requester ID for
 	 * DMA, iterate over that too.
 	 */
 	if (unlikely(pdev->dma_alias_mask)) {
 		u8 devfn;

 		for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
 			ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
 				 data);
 			if (ret)
 				return ret;
 		}
 	}

 	for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
 		struct pci_dev *tmp;

 		/* Skip virtual buses */
 		if (!bus->self)
 			continue;

 		tmp = bus->self;

 		/* stop at bridge where translation unit is associated */
 		if (tmp->dev_flags & PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT)
 			return ret;

 		/*
 		 * PCIe-to-PCI/X bridges alias transactions from downstream
 		 * devices using the subordinate bus number (PCI Express to
 		 * PCI/PCI-X Bridge Spec, rev 1.0, sec 2.3).  For all cases
 		 * where the upstream bus is PCI/X we alias to the bridge
 		 * (there are various conditions in the previous reference
 		 * where the bridge may take ownership of transactions, even
 		 * when the secondary interface is PCI-X).
 		 */
 		if (pci_is_pcie(tmp)) {
 			switch (pci_pcie_type(tmp)) {
 			case PCI_EXP_TYPE_ROOT_PORT:
 			case PCI_EXP_TYPE_UPSTREAM:
 			case PCI_EXP_TYPE_DOWNSTREAM:
 				continue;
 			case PCI_EXP_TYPE_PCI_BRIDGE:
 				ret = fn(tmp,
 					 PCI_DEVID(tmp->subordinate->number,
 						   PCI_DEVFN(0, 0)), data);
 				if (ret)
 					return ret;
 				continue;
 			case PCI_EXP_TYPE_PCIE_BRIDGE:
 				ret = fn(tmp,
 					 PCI_DEVID(tmp->bus->number,
 						   tmp->devfn), data);
 				if (ret)
 					return ret;
 				continue;
 			}
 		} else {
 			if (tmp->dev_flags & PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS)
 				ret = fn(tmp,
 					 PCI_DEVID(tmp->subordinate->number,
 						   PCI_DEVFN(0, 0)), data);
 			else
 				ret = fn(tmp,
 					 PCI_DEVID(tmp->bus->number,
 						   tmp->devfn), data);
 			if (ret)
 				return ret;
 		}
 	}

 	return ret;
 }

 static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
 {
 	struct pci_bus *child;
 	struct pci_bus *tmp;

 	if (bus->number == busnr)
 		return bus;

 	list_for_each_entry(tmp, &bus->children, node) {
 		child = pci_do_find_bus(tmp, busnr);
 		if (child)
 			return child;
 	}
 	return NULL;
 }

 /**
  * pci_find_bus - locate PCI bus from a given domain and bus number
  * @domain: number of PCI domain to search
  * @busnr: number of desired PCI bus
  *
  * Given a PCI bus number and domain number, the desired PCI bus is located
  * in the global list of PCI buses.  If the bus is found, a pointer to its
  * data structure is returned.  If no bus is found, %NULL is returned.
  */
 struct pci_bus *pci_find_bus(int domain, int busnr)
 {
 	struct pci_bus *bus = NULL;
 	struct pci_bus *tmp_bus;

 	while ((bus = pci_find_next_bus(bus)) != NULL)  {
 		if (pci_domain_nr(bus) != domain)
 			continue;
 		tmp_bus = pci_do_find_bus(bus, busnr);
 		if (tmp_bus)
 			return tmp_bus;
 	}
 	return NULL;
 }
 EXPORT_SYMBOL(pci_find_bus);

 /**
  * pci_find_next_bus - begin or continue searching for a PCI bus
  * @from: Previous PCI bus found, or %NULL for new search.
  *
  * Iterates through the list of known PCI buses.  A new search is
  * initiated by passing %NULL as the @from argument.  Otherwise if
  * @from is not %NULL, searches continue from next device on the
  * global list.
  */
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
 {
 	struct list_head *n;
 	struct pci_bus *b = NULL;

 	WARN_ON(in_interrupt());
 	down_read(&pci_bus_sem);
 	n = from ? from->node.next : pci_root_buses.next;
 	if (n != &pci_root_buses)
 		b = list_entry(n, struct pci_bus, node);
 	up_read(&pci_bus_sem);
 	return b;
 }
 EXPORT_SYMBOL(pci_find_next_bus);

 /**
  * pci_get_slot - locate PCI device for a given PCI slot
  * @bus: PCI bus on which desired PCI device resides
  * @devfn: encodes number of PCI slot in which the desired PCI
  * device resides and the logical device number within that slot
  * in case of multi-function devices.
  *
  * Given a PCI bus and slot/function number, the desired PCI device
  * is located in the list of PCI devices.
  * If the device is found, its reference count is increased and this
  * function returns a pointer to its data structure.  The caller must
  * decrement the reference count by calling pci_dev_put().
  * If no device is found, %NULL is returned.
  */
 struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn)
 {
 	struct pci_dev *dev;

 	WARN_ON(in_interrupt());
 	down_read(&pci_bus_sem);

 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		if (dev->devfn == devfn)
 			goto out;
 	}

 	dev = NULL;
  out:
 	pci_dev_get(dev);
 	up_read(&pci_bus_sem);
 	return dev;
 }
 EXPORT_SYMBOL(pci_get_slot);

 /**
  * pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot
  * @domain: PCI domain/segment on which the PCI device resides.
  * @bus: PCI bus on which desired PCI device resides
  * @devfn: encodes number of PCI slot in which the desired PCI device
  * resides and the logical device number within that slot in case of
  * multi-function devices.
  *
  * Given a PCI domain, bus, and slot/function number, the desired PCI
  * device is located in the list of PCI devices. If the device is
  * found, its reference count is increased and this function returns a
  * pointer to its data structure.  The caller must decrement the
  * reference count by calling pci_dev_put().  If no device is found,
  * %NULL is returned.
  */
 struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
 					    unsigned int devfn)
 {
 	struct pci_dev *dev = NULL;

 	for_each_pci_dev(dev) {
 		if (pci_domain_nr(dev->bus) == domain &&
 		    (dev->bus->number == bus && dev->devfn == devfn))
 			return dev;
 	}
 	return NULL;
 }
 EXPORT_SYMBOL(pci_get_domain_bus_and_slot);

 static int match_pci_dev_by_id(struct device *dev, void *data)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct pci_device_id *id = data;

 	if (pci_match_one_device(id, pdev))
 		return 1;
 	return 0;
 }

 /*
  * pci_get_dev_by_id - begin or continue searching for a PCI device by id
  * @id: pointer to struct pci_device_id to match for the device
  * @from: Previous PCI device found in search, or %NULL for new search.
  *
  * Iterates through the list of known PCI devices.  If a PCI device is found
  * with a matching id a pointer to its device structure is returned, and the
  * reference count to the device is incremented.  Otherwise, %NULL is returned.
  * A new search is initiated by passing %NULL as the @from argument.  Otherwise
  * if @from is not %NULL, searches continue from next device on the global
  * list.  The reference count for @from is always decremented if it is not
  * %NULL.
  *
  * This is an internal function for use by the other search functions in
  * this file.
  */
 static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
 					 struct pci_dev *from)
 {
 	struct device *dev;
 	struct device *dev_start = NULL;
 	struct pci_dev *pdev = NULL;

 	WARN_ON(in_interrupt());
 	if (from)
 		dev_start = &from->dev;
 	dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
 			      match_pci_dev_by_id);
 	if (dev)
 		pdev = to_pci_dev(dev);
 	pci_dev_put(from);
 	return pdev;
 }

 /**
  * pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
  * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
  * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
  * @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
  * @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
  * @from: Previous PCI device found in search, or %NULL for new search.
  *
  * Iterates through the list of known PCI devices.  If a PCI device is found
  * with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
  * device structure is returned, and the reference count to the device is
  * incremented.  Otherwise, %NULL is returned.  A new search is initiated by
  * passing %NULL as the @from argument.  Otherwise if @from is not %NULL,
  * searches continue from next device on the global list.
  * The reference count for @from is always decremented if it is not %NULL.
  */
 struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
 			       unsigned int ss_vendor, unsigned int ss_device,
 			       struct pci_dev *from)
 {
 	struct pci_device_id id = {
 		.vendor = vendor,
 		.device = device,
 		.subvendor = ss_vendor,
 		.subdevice = ss_device,
 	};

 	return pci_get_dev_by_id(&id, from);
 }
 EXPORT_SYMBOL(pci_get_subsys);

 /**
  * pci_get_device - begin or continue searching for a PCI device by vendor/device id
  * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
  * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
  * @from: Previous PCI device found in search, or %NULL for new search.
  *
  * Iterates through the list of known PCI devices.  If a PCI device is
  * found with a matching @vendor and @device, the reference count to the
  * device is incremented and a pointer to its device structure is returned.
  * Otherwise, %NULL is returned.  A new search is initiated by passing %NULL
  * as the @from argument.  Otherwise if @from is not %NULL, searches continue
  * from next device on the global list.  The reference count for @from is
  * always decremented if it is not %NULL.
  */
 struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
 			       struct pci_dev *from)
 {
 	return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
 }
 EXPORT_SYMBOL(pci_get_device);

 /**
  * pci_get_class - begin or continue searching for a PCI device by class
  * @class: search for a PCI device with this class designation
  * @from: Previous PCI device found in search, or %NULL for new search.
  *
  * Iterates through the list of known PCI devices.  If a PCI device is
  * found with a matching @class, the reference count to the device is
  * incremented and a pointer to its device structure is returned.
  * Otherwise, %NULL is returned.
  * A new search is initiated by passing %NULL as the @from argument.
  * Otherwise if @from is not %NULL, searches continue from next device
  * on the global list.  The reference count for @from is always decremented
  * if it is not %NULL.
  */
 struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
 {
 	struct pci_device_id id = {
 		.vendor = PCI_ANY_ID,
 		.device = PCI_ANY_ID,
 		.subvendor = PCI_ANY_ID,
 		.subdevice = PCI_ANY_ID,
 		.class_mask = PCI_ANY_ID,
 		.class = class,
 	};

 	return pci_get_dev_by_id(&id, from);
 }
 EXPORT_SYMBOL(pci_get_class);

 /**
  * pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
  * @ids: A pointer to a null terminated list of struct pci_device_id structures
  * that describe the type of PCI device the caller is trying to find.
  *
  * Obvious fact: You do not have a reference to any device that might be found
  * by this function, so if that device is removed from the system right after
  * this function is finished, the value will be stale.  Use this function to
  * find devices that are usually built into a system, or for a general hint as
  * to if another device happens to be present at this specific moment in time.
  */
 int pci_dev_present(const struct pci_device_id *ids)
 {
 	struct pci_dev *found = NULL;

 	WARN_ON(in_interrupt());
 	while (ids->vendor || ids->subvendor || ids->class_mask) {
 		found = pci_get_dev_by_id(ids, NULL);
 		if (found) {
 			pci_dev_put(found);
 			return 1;
 		}
 		ids++;
 	}

 	return 0;
 }
 EXPORT_SYMBOL(pci_dev_present);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* PCI searching functions
	*
	* Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
	* David Mosberger-Tang
	* Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
	* Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
	*/

	#include <linux/pci.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include "pci.h"

	DECLARE_RWSEM(pci_bus_sem);
	EXPORT_SYMBOL_GPL(pci_bus_sem);

	/*
	* pci_for_each_dma_alias - Iterate over DMA aliases for a device
	* @pdev: starting downstream device
	* @fn: function to call for each alias
	* @data: opaque data to pass to @fn
	*
	* Starting @pdev, walk up the bus calling @fn for each possible alias
	* of @pdev at the root bus.
	*/
	int pci_for_each_dma_alias(struct pci_dev *pdev,
	int (fn)(struct pci_dev pdev,
	u16 alias, void data), void data)
	{
	struct pci_bus *bus;
	int ret;

	ret = fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn), data);
	if (ret)
	return ret;

	/*
	* If the device is broken and uses an alias requester ID for
	* DMA, iterate over that too.
	*/
	if (unlikely(pdev->dma_alias_mask)) {
	u8 devfn;

	for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
	ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
	data);
	if (ret)
	return ret;
	}
	}

	for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
	struct pci_dev *tmp;

	/* Skip virtual buses */
	if (!bus->self)
	continue;

	tmp = bus->self;

	/* stop at bridge where translation unit is associated */
	if (tmp->dev_flags & PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT)
	return ret;

	/*
	* PCIe-to-PCI/X bridges alias transactions from downstream
	* devices using the subordinate bus number (PCI Express to
	* PCI/PCI-X Bridge Spec, rev 1.0, sec 2.3). For all cases
	* where the upstream bus is PCI/X we alias to the bridge
	* (there are various conditions in the previous reference
	* where the bridge may take ownership of transactions, even
	* when the secondary interface is PCI-X).
	*/
	if (pci_is_pcie(tmp)) {
	switch (pci_pcie_type(tmp)) {
	case PCI_EXP_TYPE_ROOT_PORT:
	case PCI_EXP_TYPE_UPSTREAM:
	case PCI_EXP_TYPE_DOWNSTREAM:
	continue;
	case PCI_EXP_TYPE_PCI_BRIDGE:
	ret = fn(tmp,
	PCI_DEVID(tmp->subordinate->number,
	PCI_DEVFN(0, 0)), data);
	if (ret)
	return ret;
	continue;
	case PCI_EXP_TYPE_PCIE_BRIDGE:
	ret = fn(tmp,
	PCI_DEVID(tmp->bus->number,
	tmp->devfn), data);
	if (ret)
	return ret;
	continue;
	}
	} else {
	if (tmp->dev_flags & PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS)
	ret = fn(tmp,
	PCI_DEVID(tmp->subordinate->number,
	PCI_DEVFN(0, 0)), data);
	else
	ret = fn(tmp,
	PCI_DEVID(tmp->bus->number,
	tmp->devfn), data);
	if (ret)
	return ret;
	}
	}

	return ret;
	}

	static struct pci_bus pci_do_find_bus(struct pci_bus bus, unsigned char busnr)
	{
	struct pci_bus *child;
	struct pci_bus *tmp;

	if (bus->number == busnr)
	return bus;

	list_for_each_entry(tmp, &bus->children, node) {
	child = pci_do_find_bus(tmp, busnr);
	if (child)
	return child;
	}
	return NULL;
	}

	/**
	* pci_find_bus - locate PCI bus from a given domain and bus number
	* @domain: number of PCI domain to search
	* @busnr: number of desired PCI bus
	*
	* Given a PCI bus number and domain number, the desired PCI bus is located
	* in the global list of PCI buses. If the bus is found, a pointer to its
	* data structure is returned. If no bus is found, %NULL is returned.
	*/
	struct pci_bus *pci_find_bus(int domain, int busnr)
	{
	struct pci_bus *bus = NULL;
	struct pci_bus *tmp_bus;

	while ((bus = pci_find_next_bus(bus)) != NULL) {
	if (pci_domain_nr(bus) != domain)
	continue;
	tmp_bus = pci_do_find_bus(bus, busnr);
	if (tmp_bus)
	return tmp_bus;
	}
	return NULL;
	}
	EXPORT_SYMBOL(pci_find_bus);

	/**
	* pci_find_next_bus - begin or continue searching for a PCI bus
	* @from: Previous PCI bus found, or %NULL for new search.
	*
	* Iterates through the list of known PCI buses. A new search is
	* initiated by passing %NULL as the @from argument. Otherwise if
	* @from is not %NULL, searches continue from next device on the
	* global list.
	*/
	struct pci_bus pci_find_next_bus(const struct pci_bus from)
	{
	struct list_head *n;
	struct pci_bus *b = NULL;

	WARN_ON(in_interrupt());
	down_read(&pci_bus_sem);
	n = from ? from->node.next : pci_root_buses.next;
	if (n != &pci_root_buses)
	b = list_entry(n, struct pci_bus, node);
	up_read(&pci_bus_sem);
	return b;
	}
	EXPORT_SYMBOL(pci_find_next_bus);

	/**
	* pci_get_slot - locate PCI device for a given PCI slot
	* @bus: PCI bus on which desired PCI device resides
	* @devfn: encodes number of PCI slot in which the desired PCI
	* device resides and the logical device number within that slot
	* in case of multi-function devices.
	*
	* Given a PCI bus and slot/function number, the desired PCI device
	* is located in the list of PCI devices.
	* If the device is found, its reference count is increased and this
	* function returns a pointer to its data structure. The caller must
	* decrement the reference count by calling pci_dev_put().
	* If no device is found, %NULL is returned.
	*/
	struct pci_dev pci_get_slot(struct pci_bus bus, unsigned int devfn)
	{
	struct pci_dev *dev;

	WARN_ON(in_interrupt());
	down_read(&pci_bus_sem);

	list_for_each_entry(dev, &bus->devices, bus_list) {
	if (dev->devfn == devfn)
	goto out;
	}

	dev = NULL;
	out:
	pci_dev_get(dev);
	up_read(&pci_bus_sem);
	return dev;
	}
	EXPORT_SYMBOL(pci_get_slot);

	/**
	* pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot
	* @domain: PCI domain/segment on which the PCI device resides.
	* @bus: PCI bus on which desired PCI device resides
	* @devfn: encodes number of PCI slot in which the desired PCI device
	* resides and the logical device number within that slot in case of
	* multi-function devices.
	*
	* Given a PCI domain, bus, and slot/function number, the desired PCI
	* device is located in the list of PCI devices. If the device is
	* found, its reference count is increased and this function returns a
	* pointer to its data structure. The caller must decrement the
	* reference count by calling pci_dev_put(). If no device is found,
	* %NULL is returned.
	*/
	struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
	unsigned int devfn)
	{
	struct pci_dev *dev = NULL;

	for_each_pci_dev(dev) {
	if (pci_domain_nr(dev->bus) == domain &&
	(dev->bus->number == bus && dev->devfn == devfn))
	return dev;
	}
	return NULL;
	}
	EXPORT_SYMBOL(pci_get_domain_bus_and_slot);

	static int match_pci_dev_by_id(struct device dev, void data)
	{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct pci_device_id *id = data;

	if (pci_match_one_device(id, pdev))
	return 1;
	return 0;
	}

	/*
	* pci_get_dev_by_id - begin or continue searching for a PCI device by id
	* @id: pointer to struct pci_device_id to match for the device
	* @from: Previous PCI device found in search, or %NULL for new search.
	*
	* Iterates through the list of known PCI devices. If a PCI device is found
	* with a matching id a pointer to its device structure is returned, and the
	* reference count to the device is incremented. Otherwise, %NULL is returned.
	* A new search is initiated by passing %NULL as the @from argument. Otherwise
	* if @from is not %NULL, searches continue from next device on the global
	* list. The reference count for @from is always decremented if it is not
	* %NULL.
	*
	* This is an internal function for use by the other search functions in
	* this file.
	*/
	static struct pci_dev pci_get_dev_by_id(const struct pci_device_id id,
	struct pci_dev *from)
	{
	struct device *dev;
	struct device *dev_start = NULL;
	struct pci_dev *pdev = NULL;

	WARN_ON(in_interrupt());
	if (from)
	dev_start = &from->dev;
	dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
	match_pci_dev_by_id);
	if (dev)
	pdev = to_pci_dev(dev);
	pci_dev_put(from);
	return pdev;
	}

	/**
	* pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
	* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
	* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
	* @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
	* @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
	* @from: Previous PCI device found in search, or %NULL for new search.
	*
	* Iterates through the list of known PCI devices. If a PCI device is found
	* with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
	* device structure is returned, and the reference count to the device is
	* incremented. Otherwise, %NULL is returned. A new search is initiated by
	* passing %NULL as the @from argument. Otherwise if @from is not %NULL,
	* searches continue from next device on the global list.
	* The reference count for @from is always decremented if it is not %NULL.
	*/
	struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
	unsigned int ss_vendor, unsigned int ss_device,
	struct pci_dev *from)
	{
	struct pci_device_id id = {
	.vendor = vendor,
	.device = device,
	.subvendor = ss_vendor,
	.subdevice = ss_device,
	};

	return pci_get_dev_by_id(&id, from);
	}
	EXPORT_SYMBOL(pci_get_subsys);

	/**
	* pci_get_device - begin or continue searching for a PCI device by vendor/device id
	* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
	* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
	* @from: Previous PCI device found in search, or %NULL for new search.
	*
	* Iterates through the list of known PCI devices. If a PCI device is
	* found with a matching @vendor and @device, the reference count to the
	* device is incremented and a pointer to its device structure is returned.
	* Otherwise, %NULL is returned. A new search is initiated by passing %NULL
	* as the @from argument. Otherwise if @from is not %NULL, searches continue
	* from next device on the global list. The reference count for @from is
	* always decremented if it is not %NULL.
	*/
	struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
	struct pci_dev *from)
	{
	return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
	}
	EXPORT_SYMBOL(pci_get_device);

	/**
	* pci_get_class - begin or continue searching for a PCI device by class
	* @class: search for a PCI device with this class designation
	* @from: Previous PCI device found in search, or %NULL for new search.
	*
	* Iterates through the list of known PCI devices. If a PCI device is
	* found with a matching @class, the reference count to the device is
	* incremented and a pointer to its device structure is returned.
	* Otherwise, %NULL is returned.
	* A new search is initiated by passing %NULL as the @from argument.
	* Otherwise if @from is not %NULL, searches continue from next device
	* on the global list. The reference count for @from is always decremented
	* if it is not %NULL.
	*/
	struct pci_dev pci_get_class(unsigned int class, struct pci_dev from)
	{
	struct pci_device_id id = {
	.vendor = PCI_ANY_ID,
	.device = PCI_ANY_ID,
	.subvendor = PCI_ANY_ID,
	.subdevice = PCI_ANY_ID,
	.class_mask = PCI_ANY_ID,
	.class = class,
	};

	return pci_get_dev_by_id(&id, from);
	}
	EXPORT_SYMBOL(pci_get_class);

	/**
	* pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
	* @ids: A pointer to a null terminated list of struct pci_device_id structures
	* that describe the type of PCI device the caller is trying to find.
	*
	* Obvious fact: You do not have a reference to any device that might be found
	* by this function, so if that device is removed from the system right after
	* this function is finished, the value will be stale. Use this function to
	* find devices that are usually built into a system, or for a general hint as
	* to if another device happens to be present at this specific moment in time.
	*/
	int pci_dev_present(const struct pci_device_id *ids)
	{
	struct pci_dev *found = NULL;

	WARN_ON(in_interrupt());
	while (ids->vendor \|\| ids->subvendor \|\| ids->class_mask) {
	found = pci_get_dev_by_id(ids, NULL);
	if (found) {
	pci_dev_put(found);
	return 1;
	}
	ids++;
	}

	return 0;
	}
	EXPORT_SYMBOL(pci_dev_present);