// SPDX-License-Identifier: GPL-2.0

  /*
   * Simple stub driver to reserve a PCI device

   *
   * Copyright (C) 2008 Red Hat, Inc.
   * Author:

   *	Chris Wright

   *

   * Usage is simple, allocate a new id to the stub driver and bind the
   * device to it.  For example:

   *

   * # echo "8086 10f5" > /sys/bus/pci/drivers/pci-stub/new_id
   * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
   * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/pci-stub/bind
   * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
   * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/pci-stub
   */
  
  #include <linux/module.h>
  #include <linux/pci.h>

  static char ids[1024] __initdata;
  
  module_param_string(ids, ids, sizeof(ids), 0);
  MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the stub driver, format is "
  		 "\"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\""
  		 " and multiple comma separated entries can be specified");

  static int pci_stub_probe(struct pci_dev *dev, const struct pci_device_id *id)
  {

  	pci_info(dev, "claimed by stub
  ");

  	return 0;
  }
  
  static struct pci_driver stub_driver = {
  	.name		= "pci-stub",
  	.id_table	= NULL,	/* only dynamic id's */
  	.probe		= pci_stub_probe,
  };
  
  static int __init pci_stub_init(void)
  {

  	char *p, *id;
  	int rc;
  
  	rc = pci_register_driver(&stub_driver);
  	if (rc)
  		return rc;

  	/* no ids passed actually */
  	if (ids[0] == '\0')
  		return 0;

  	/* add ids specified in the module parameter */
  	p = ids;
  	while ((id = strsep(&p, ","))) {
  		unsigned int vendor, device, subvendor = PCI_ANY_ID,

  			subdevice = PCI_ANY_ID, class = 0, class_mask = 0;

  		int fields;

  		if (!strlen(id))
  			continue;

  		fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
  				&vendor, &device, &subvendor, &subdevice,
  				&class, &class_mask);
  
  		if (fields < 2) {

  			pr_warn("pci-stub: invalid ID string \"%s\"
  ", id);

  			continue;
  		}

  		pr_info("pci-stub: add %04X:%04X sub=%04X:%04X cls=%08X/%08X
  ",

  		       vendor, device, subvendor, subdevice, class, class_mask);
  
  		rc = pci_add_dynid(&stub_driver, vendor, device,
  				   subvendor, subdevice, class, class_mask, 0);
  		if (rc)

  			pr_warn("pci-stub: failed to add dynamic ID (%d)
  ",
  				rc);

  	}
  
  	return 0;

  }
  
  static void __exit pci_stub_exit(void)
  {
  	pci_unregister_driver(&stub_driver);
  }
  
  module_init(pci_stub_init);
  module_exit(pci_stub_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Chris Wright <chrisw@sous-sol.org>");