PCI: pci-stub: add pci_stub.ids parameter

Add ids module parameter which allows specifying initial IDs for the
pci-stub driver.  When built into the kernel, pci-stub is linked
before any real pci drivers and by setting up IDs from initialization
it can prevent built-in drivers from attaching to specific devices.

While at it, make pci_stub_probe() print out about devices it grabbed
to weed out "but my controller isn't being probed" bug reports.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci-stub.c

@@ -19,8 +19,16 @@
 #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)
 {
+	dev_printk(KERN_INFO, &dev->dev, "claimed by stub\n");
 	return 0;
 }
 
@@ -32,7 +40,42 @@ static struct pci_driver stub_driver = {
 
 static int __init pci_stub_init(void)
 {
-	return pci_register_driver(&stub_driver);
+	char *p, *id;
+	int rc;
+
+	rc = pci_register_driver(&stub_driver);
+	if (rc)
+		return rc;
+
+	/* 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;
+
+		fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
+				&vendor, &device, &subvendor, &subdevice,
+				&class, &class_mask);
+
+		if (fields < 2) {
+			printk(KERN_WARNING
+			       "pci-stub: invalid id string \"%s\"\n", id);
+			continue;
+		}
+
+		printk(KERN_INFO
+		       "pci-stub: add %04X:%04X sub=%04X:%04X cls=%08X/%08X\n",
+		       vendor, device, subvendor, subdevice, class, class_mask);
+
+		rc = pci_add_dynid(&stub_driver, vendor, device,
+				   subvendor, subdevice, class, class_mask, 0);
+		if (rc)
+			printk(KERN_WARNING
+			       "pci-stub: failed to add dynamic id (%d)\n", rc);
+	}
+
+	return 0;
 }
 
 static void __exit pci_stub_exit(void)