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 
pci_stub_probe(struct pci_dev * dev,const struct pci_device_id * id)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 };
40 
pci_stub_init(void)41 static int __init pci_stub_init(void)
42 {
43 	char *p, *id;
44 	int rc;
45 
46 	rc = pci_register_driver(&stub_driver);
47 	if (rc)
48 		return rc;
49 
50 	/* no ids passed actually */
51 	if (ids[0] == '\0')
52 		return 0;
53 
54 	/* add ids specified in the module parameter */
55 	p = ids;
56 	while ((id = strsep(&p, ","))) {
57 		unsigned int vendor, device, subvendor = PCI_ANY_ID,
58 			subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
59 		int fields;
60 
61 		if (!strlen(id))
62 			continue;
63 
64 		fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
65 				&vendor, &device, &subvendor, &subdevice,
66 				&class, &class_mask);
67 
68 		if (fields < 2) {
69 			pr_warn("pci-stub: invalid ID string \"%s\"\n", id);
70 			continue;
71 		}
72 
73 		pr_info("pci-stub: add %04X:%04X sub=%04X:%04X cls=%08X/%08X\n",
74 		       vendor, device, subvendor, subdevice, class, class_mask);
75 
76 		rc = pci_add_dynid(&stub_driver, vendor, device,
77 				   subvendor, subdevice, class, class_mask, 0);
78 		if (rc)
79 			pr_warn("pci-stub: failed to add dynamic ID (%d)\n",
80 				rc);
81 	}
82 
83 	return 0;
84 }
85 
pci_stub_exit(void)86 static void __exit pci_stub_exit(void)
87 {
88 	pci_unregister_driver(&stub_driver);
89 }
90 
91 module_init(pci_stub_init);
92 module_exit(pci_stub_exit);
93 
94 MODULE_LICENSE("GPL");
95 MODULE_AUTHOR("Chris Wright <chrisw@sous-sol.org>");
96