drivers/pci/search.c - kernel/msm-4.9 - Gitiles

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

 DECLARE_RWSEM(pci_bus_sem);
 /*
  * find the upstream PCIE-to-PCI bridge of a PCI device
  * if the device is PCIE, return NULL
  * if the device isn't connected to a PCIE bridge (that is its parent is a
  * legacy PCI bridge and the bridge is directly connected to bus 0), return its
  * parent
  */
 struct pci_dev *
 pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
 {
 	struct pci_dev *tmp = NULL;

 	if (pdev->is_pcie)
 		return NULL;
 	while (1) {
 		if (!pdev->bus->self)
 			break;
 		pdev = pdev->bus->self;
 		/* a p2p bridge */
 		if (!pdev->is_pcie) {
 			tmp = pdev;
 			continue;
 		}
 		/* PCI device should connect to a PCIE bridge */
 		if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
 			/* Busted hardware? */
 			WARN_ON_ONCE(1);
 			return NULL;
 		}
 		return pdev;
 	}

 	return tmp;
 }

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

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

 	list_for_each(tmp, &bus->children) {
 		child = pci_do_find_bus(pci_bus_b(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;
 }

 /**
  * 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 busses.  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 = pci_bus_b(n);
 	up_read(&pci_bus_sem);
 	return b;
 }

 #ifdef CONFIG_PCI_LEGACY
 /**
  * pci_find_slot - locate PCI device from a given PCI slot
  * @bus: number of 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 system global list of PCI devices.  If the device
  * is found, a pointer to its data structure is returned.  If no
  * device is found, %NULL is returned.
  *
  * NOTE: Do not use this function any more; use pci_get_slot() instead, as
  * the PCI device returned by this function can disappear at any moment in
  * time.
  */
 struct pci_dev *pci_find_slot(unsigned int bus, unsigned int devfn)
 {
 	struct pci_dev *dev = NULL;

 	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 		if (dev->bus->number == bus && dev->devfn == devfn) {
 			pci_dev_put(dev);
 			return dev;
 		}
 	}
 	return NULL;
 }
 EXPORT_SYMBOL(pci_find_slot);

 /**
  * pci_find_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, 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.
  *
  * NOTE: Do not use this function any more; use pci_get_device() instead, as
  * the PCI device returned by this function can disappear at any moment in
  * time.
  */
 struct pci_dev *pci_find_device(unsigned int vendor, unsigned int device,
 				const struct pci_dev *from)
 {
 	struct pci_dev *pdev;

 	pdev = pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
 	pci_dev_put(pdev);
 	return pdev;
 }
 EXPORT_SYMBOL(pci_find_device);
 #endif /* CONFIG_PCI_LEGACY */

 /**
  * 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 list_head *tmp;
 	struct pci_dev *dev;

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

 	list_for_each(tmp, &bus->devices) {
 		dev = pci_dev_b(tmp);
 		if (dev->devfn == devfn)
 			goto out;
 	}

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

 /**
  * pci_get_bus_and_slot - locate PCI device from a given PCI bus & slot
  * @bus: number of 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.
  *
  * Note: the bus/slot search is limited to PCI domain (segment) 0.
  *
  * Given a PCI bus and slot/function number, the desired PCI device
  * is located in system global list of PCI devices.  If the device
  * is found, a pointer to its data structure is returned.  If no
  * device is found, %NULL is returned. The returned device has its
  * reference count bumped by one.
  */

 struct pci_dev * pci_get_bus_and_slot(unsigned int bus, unsigned int devfn)
 {
 	struct pci_dev *dev = NULL;

 	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
 		if (pci_domain_nr(dev->bus) == 0 &&
 		   (dev->bus->number == bus && dev->devfn == devfn))
 			return dev;
 	}
 	return NULL;
 }

 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,
 					 const struct pci_dev *from)
 {
 	struct device *dev;
 	struct device *dev_start = NULL;
 	struct pci_dev *pdev = NULL;

 	WARN_ON(in_interrupt());
 	if (from) {
 		/* FIXME
 		 * take the cast off, when bus_find_device is made const.
 		 */
 		dev_start = (struct device *)&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);
 	if (from)
 		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,
 			       const struct pci_dev *from)
 {
 	struct pci_dev *pdev;
 	struct pci_device_id *id;

 	/*
 	 * pci_find_subsys() can be called on the ide_setup() path,
 	 * super-early in boot.  But the down_read() will enable local
 	 * interrupts, which can cause some machines to crash.  So here we
 	 * detect and flag that situation and bail out early.
 	 */
 	if (unlikely(no_pci_devices()))
 		return NULL;

 	id = kzalloc(sizeof(*id), GFP_KERNEL);
 	if (!id)
 		return NULL;
 	id->vendor = vendor;
 	id->device = device;
 	id->subvendor = ss_vendor;
 	id->subdevice = ss_device;

 	pdev = pci_get_dev_by_id(id, from);
 	kfree(id);

 	return pdev;
 }

 /**
  * 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);
 }

 /**
  * 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_dev *dev;
 	struct pci_device_id *id;

 	id = kzalloc(sizeof(*id), GFP_KERNEL);
 	if (!id)
 		return NULL;
 	id->vendor = id->device = id->subvendor = id->subdevice = PCI_ANY_ID;
 	id->class_mask = PCI_ANY_ID;
 	id->class = class;

 	dev = pci_get_dev_by_id(id, from);
 	kfree(id);
 	return dev;
 }

 /**
  * 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)
 			goto exit;
 		ids++;
 	}
 exit:
 	if (found)
 		return 1;
 	return 0;
 }
 EXPORT_SYMBOL(pci_dev_present);

 /* For boot time work */
 EXPORT_SYMBOL(pci_find_bus);
 EXPORT_SYMBOL(pci_find_next_bus);
 /* For everyone */
 EXPORT_SYMBOL(pci_get_device);
 EXPORT_SYMBOL(pci_get_subsys);
 EXPORT_SYMBOL(pci_get_slot);
 EXPORT_SYMBOL(pci_get_bus_and_slot);
 EXPORT_SYMBOL(pci_get_class);
	/*
	* 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/init.h>
	#include <linux/pci.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include "pci.h"

	DECLARE_RWSEM(pci_bus_sem);
	/*
	* find the upstream PCIE-to-PCI bridge of a PCI device
	* if the device is PCIE, return NULL
	* if the device isn't connected to a PCIE bridge (that is its parent is a
	* legacy PCI bridge and the bridge is directly connected to bus 0), return its
	* parent
	*/
	struct pci_dev *
	pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
	{
	struct pci_dev *tmp = NULL;

	if (pdev->is_pcie)
	return NULL;
	while (1) {
	if (!pdev->bus->self)
	break;
	pdev = pdev->bus->self;
	/* a p2p bridge */
	if (!pdev->is_pcie) {
	tmp = pdev;
	continue;
	}
	/* PCI device should connect to a PCIE bridge */
	if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
	/* Busted hardware? */
	WARN_ON_ONCE(1);
	return NULL;
	}
	return pdev;
	}

	return tmp;
	}

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

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

	list_for_each(tmp, &bus->children) {
	child = pci_do_find_bus(pci_bus_b(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;
	}

	/**
	* 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 busses. 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 = pci_bus_b(n);
	up_read(&pci_bus_sem);
	return b;
	}

	#ifdef CONFIG_PCI_LEGACY
	/**
	* pci_find_slot - locate PCI device from a given PCI slot
	* @bus: number of 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 system global list of PCI devices. If the device
	* is found, a pointer to its data structure is returned. If no
	* device is found, %NULL is returned.
	*
	* NOTE: Do not use this function any more; use pci_get_slot() instead, as
	* the PCI device returned by this function can disappear at any moment in
	* time.
	*/
	struct pci_dev *pci_find_slot(unsigned int bus, unsigned int devfn)
	{
	struct pci_dev *dev = NULL;

	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
	if (dev->bus->number == bus && dev->devfn == devfn) {
	pci_dev_put(dev);
	return dev;
	}
	}
	return NULL;
	}
	EXPORT_SYMBOL(pci_find_slot);

	/**
	* pci_find_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, 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.
	*
	* NOTE: Do not use this function any more; use pci_get_device() instead, as
	* the PCI device returned by this function can disappear at any moment in
	* time.
	*/
	struct pci_dev *pci_find_device(unsigned int vendor, unsigned int device,
	const struct pci_dev *from)
	{
	struct pci_dev *pdev;

	pdev = pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
	pci_dev_put(pdev);
	return pdev;
	}
	EXPORT_SYMBOL(pci_find_device);
	#endif /* CONFIG_PCI_LEGACY */

	/**
	* 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 list_head *tmp;
	struct pci_dev *dev;

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

	list_for_each(tmp, &bus->devices) {
	dev = pci_dev_b(tmp);
	if (dev->devfn == devfn)
	goto out;
	}

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

	/**
	* pci_get_bus_and_slot - locate PCI device from a given PCI bus & slot
	* @bus: number of 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.
	*
	* Note: the bus/slot search is limited to PCI domain (segment) 0.
	*
	* Given a PCI bus and slot/function number, the desired PCI device
	* is located in system global list of PCI devices. If the device
	* is found, a pointer to its data structure is returned. If no
	* device is found, %NULL is returned. The returned device has its
	* reference count bumped by one.
	*/

	struct pci_dev * pci_get_bus_and_slot(unsigned int bus, unsigned int devfn)
	{
	struct pci_dev *dev = NULL;

	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
	if (pci_domain_nr(dev->bus) == 0 &&
	(dev->bus->number == bus && dev->devfn == devfn))
	return dev;
	}
	return NULL;
	}

	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,
	const struct pci_dev *from)
	{
	struct device *dev;
	struct device *dev_start = NULL;
	struct pci_dev *pdev = NULL;

	WARN_ON(in_interrupt());
	if (from) {
	/* FIXME
	* take the cast off, when bus_find_device is made const.
	*/
	dev_start = (struct device *)&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);
	if (from)
	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,
	const struct pci_dev *from)
	{
	struct pci_dev *pdev;
	struct pci_device_id *id;

	/*
	* pci_find_subsys() can be called on the ide_setup() path,
	* super-early in boot. But the down_read() will enable local
	* interrupts, which can cause some machines to crash. So here we
	* detect and flag that situation and bail out early.
	*/
	if (unlikely(no_pci_devices()))
	return NULL;

	id = kzalloc(sizeof(*id), GFP_KERNEL);
	if (!id)
	return NULL;
	id->vendor = vendor;
	id->device = device;
	id->subvendor = ss_vendor;
	id->subdevice = ss_device;

	pdev = pci_get_dev_by_id(id, from);
	kfree(id);

	return pdev;
	}

	/**
	* 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);
	}

	/**
	* 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_dev *dev;
	struct pci_device_id *id;

	id = kzalloc(sizeof(*id), GFP_KERNEL);
	if (!id)
	return NULL;
	id->vendor = id->device = id->subvendor = id->subdevice = PCI_ANY_ID;
	id->class_mask = PCI_ANY_ID;
	id->class = class;

	dev = pci_get_dev_by_id(id, from);
	kfree(id);
	return dev;
	}

	/**
	* 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)
	goto exit;
	ids++;
	}
	exit:
	if (found)
	return 1;
	return 0;
	}
	EXPORT_SYMBOL(pci_dev_present);

	/* For boot time work */
	EXPORT_SYMBOL(pci_find_bus);
	EXPORT_SYMBOL(pci_find_next_bus);
	/* For everyone */
	EXPORT_SYMBOL(pci_get_device);
	EXPORT_SYMBOL(pci_get_subsys);
	EXPORT_SYMBOL(pci_get_slot);
	EXPORT_SYMBOL(pci_get_bus_and_slot);
	EXPORT_SYMBOL(pci_get_class);