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 	.driver_managed_dma = true,
40 };
41 
pci_stub_init(void)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 
pci_stub_exit(void)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_LICENSE("GPL");
96 MODULE_AUTHOR("Chris Wright <chrisw@sous-sol.org>");
97