// SPDX-License-Identifier: GPL-2.0
/*
 * Helpful private functions copied from elsewhere in the kernel tree
 * DO NOT MODIFY
 */
#include <linux/version.h>

// Functions from drivers/pci/pci.h
/**
 * pci_match_one_device - Tell if a PCI device structure has a matching
 *			  PCI device id structure
 * @id: single PCI device id structure to match
 * @dev: the PCI device structure to match against
 *
 * Returns the matching pci_device_id structure or %NULL if there is no match.
 */
static inline const struct pci_device_id *
pci_match_one_device(const struct pci_device_id *id, const struct pci_dev *dev)
{
	if ((id->vendor == PCI_ANY_ID || id->vendor == dev->vendor) &&
	    (id->device == PCI_ANY_ID || id->device == dev->device) &&
	    (id->subvendor == PCI_ANY_ID || id->subvendor == dev->subsystem_vendor) &&
	    (id->subdevice == PCI_ANY_ID || id->subdevice == dev->subsystem_device) &&
	    !((id->class ^ dev->class) & id->class_mask))
		return id;
	return NULL;
}

// Functions from drivers/pci/search.h
#include <linux/device.h>
#include <linux/pci.h>
extern struct bus_type pci_bus_type;

#if LINUX_VERSION_CODE < KERNEL_VERSION(5,3,0)
static int match_pci_dev_by_id(struct device *dev, void *data)
#else
static int match_pci_dev_by_id(struct device *dev, const void *data)
#endif
{
	struct pci_dev *pdev = to_pci_dev(dev);
	const 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;

	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;
}