drivers/pci/pci-stub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Simple stub driver to reserve a PCI device
   4  *
   5  * Copyright (C) 2008 Red Hat, Inc.
   6  * Author:
   7  *      Chris Wright
   8  *
   9  * Usage is simple, allocate a new id to the stub driver and bind the
  10  * device to it.  For example:
  11  *
  12  * # echo "8086 10f5" > /sys/bus/pci/drivers/pci-stub/new_id
  13  * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
  14  * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/pci-stub/bind
  15  * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
  16  * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/pci-stub
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/pci.h>
  21
  22 static char ids[1024] __initdata;
  23
  24 module_param_string(ids, ids, sizeof(ids), 0);
  25 MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the stub driver, format is "
  26                  "\"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\""
  27                  " and multiple comma separated entries can be specified");
  28
  29 static int pci_stub_probe(struct pci_dev *dev, const struct pci_device_id *id)
  30 {
  31         pci_info(dev, "claimed by stub\n");
  32         return 0;
  33 }
  34
  35 static struct pci_driver stub_driver = {
  36         .name           = "pci-stub",
  37         .id_table       = NULL, /* only dynamic id's */
  38         .probe          = pci_stub_probe,
  39         .driver_managed_dma = true,
  40 };
  41
  42 static int __init pci_stub_init(void)
  43 {
  44         char *p, *id;
  45         int rc;
  46
  47         rc = pci_register_driver(&stub_driver);
  48         if (rc)
  49                 return rc;
  50
  51         /* no ids passed actually */
  52         if (ids[0] == '\0')
  53                 return 0;
  54
  55         /* add ids specified in the module parameter */
  56         p = ids;
  57         while ((id = strsep(&p, ","))) {
  58                 unsigned int vendor, device, subvendor = PCI_ANY_ID,
  59                         subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
  60                 int fields;
  61
  62                 if (!strlen(id))
  63                         continue;
  64
  65                 fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
  66                                 &vendor, &device, &subvendor, &subdevice,
  67                                 &class, &class_mask);
  68
  69                 if (fields < 2) {
  70                         pr_warn("pci-stub: invalid ID string \"%s\"\n", id);
  71                         continue;
  72                 }
  73
  74                 pr_info("pci-stub: add %04X:%04X sub=%04X:%04X cls=%08X/%08X\n",
  75                        vendor, device, subvendor, subdevice, class, class_mask);
  76
  77                 rc = pci_add_dynid(&stub_driver, vendor, device,
  78                                    subvendor, subdevice, class, class_mask, 0);
  79                 if (rc)
  80                         pr_warn("pci-stub: failed to add dynamic ID (%d)\n",
  81                                 rc);
  82         }
  83
  84         return 0;
  85 }
  86
  87 static void __exit pci_stub_exit(void)
  88 {
  89         pci_unregister_driver(&stub_driver);
  90 }
  91
  92 module_init(pci_stub_init);
  93 module_exit(pci_stub_exit);
  94
  95 MODULE_DESCRIPTION("VM device assignment stub driver");
  96 MODULE_LICENSE("GPL");
  97 MODULE_AUTHOR("Chris Wright <chrisw@sous-sol.org>");