text: /*
   *	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->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN)) {
  		ret = fn(pdev, PCI_DEVID(pdev->bus->number,
  					 pdev->dma_alias_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;
  
  		/*
  		 * 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);
  	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,
  			       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);
  