1/*
2 * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
3 *
4 * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
5 *
6 * based on drivers/usb/usb.c which had the following copyrights:
7 *	(C) Copyright Linus Torvalds 1999
8 *	(C) Copyright Johannes Erdfelt 1999-2001
9 *	(C) Copyright Andreas Gal 1999
10 *	(C) Copyright Gregory P. Smith 1999
11 *	(C) Copyright Deti Fliegl 1999 (new USB architecture)
12 *	(C) Copyright Randy Dunlap 2000
13 *	(C) Copyright David Brownell 2000-2004
14 *	(C) Copyright Yggdrasil Computing, Inc. 2000
15 *		(usb_device_id matching changes by Adam J. Richter)
16 *	(C) Copyright Greg Kroah-Hartman 2002-2003
17 *
18 */
19
20#include <linux/usb.h>
21#include <linux/usb/hcd.h>
22#include "usb.h"
23
24static inline const char *plural(int n)
25{
26	return (n == 1 ? "" : "s");
27}
28
29static int is_rndis(struct usb_interface_descriptor *desc)
30{
31	return desc->bInterfaceClass == USB_CLASS_COMM
32		&& desc->bInterfaceSubClass == 2
33		&& desc->bInterfaceProtocol == 0xff;
34}
35
36static int is_activesync(struct usb_interface_descriptor *desc)
37{
38	return desc->bInterfaceClass == USB_CLASS_MISC
39		&& desc->bInterfaceSubClass == 1
40		&& desc->bInterfaceProtocol == 1;
41}
42
43int usb_choose_configuration(struct usb_device *udev)
44{
45	int i;
46	int num_configs;
47	int insufficient_power = 0;
48	struct usb_host_config *c, *best;
49
50	if (usb_device_is_owned(udev))
51		return 0;
52
53	best = NULL;
54	c = udev->config;
55	num_configs = udev->descriptor.bNumConfigurations;
56	for (i = 0; i < num_configs; (i++, c++)) {
57		struct usb_interface_descriptor	*desc = NULL;
58
59		/* It's possible that a config has no interfaces! */
60		if (c->desc.bNumInterfaces > 0)
61			desc = &c->intf_cache[0]->altsetting->desc;
62
63		/*
64		 * HP's USB bus-powered keyboard has only one configuration
65		 * and it claims to be self-powered; other devices may have
66		 * similar errors in their descriptors.  If the next test
67		 * were allowed to execute, such configurations would always
68		 * be rejected and the devices would not work as expected.
69		 * In the meantime, we run the risk of selecting a config
70		 * that requires external power at a time when that power
71		 * isn't available.  It seems to be the lesser of two evils.
72		 *
73		 * Bugzilla #6448 reports a device that appears to crash
74		 * when it receives a GET_DEVICE_STATUS request!  We don't
75		 * have any other way to tell whether a device is self-powered,
76		 * but since we don't use that information anywhere but here,
77		 * the call has been removed.
78		 *
79		 * Maybe the GET_DEVICE_STATUS call and the test below can
80		 * be reinstated when device firmwares become more reliable.
81		 * Don't hold your breath.
82		 */
83#if 0
84		/* Rule out self-powered configs for a bus-powered device */
85		if (bus_powered && (c->desc.bmAttributes &
86					USB_CONFIG_ATT_SELFPOWER))
87			continue;
88#endif
89
90		/*
91		 * The next test may not be as effective as it should be.
92		 * Some hubs have errors in their descriptor, claiming
93		 * to be self-powered when they are really bus-powered.
94		 * We will overestimate the amount of current such hubs
95		 * make available for each port.
96		 *
97		 * This is a fairly benign sort of failure.  It won't
98		 * cause us to reject configurations that we should have
99		 * accepted.
100		 */
101
102		/* Rule out configs that draw too much bus current */
103		if (usb_get_max_power(udev, c) > udev->bus_mA) {
104			insufficient_power++;
105			continue;
106		}
107
108		/* When the first config's first interface is one of Microsoft's
109		 * pet nonstandard Ethernet-over-USB protocols, ignore it unless
110		 * this kernel has enabled the necessary host side driver.
111		 * But: Don't ignore it if it's the only config.
112		 */
113		if (i == 0 && num_configs > 1 && desc &&
114				(is_rndis(desc) || is_activesync(desc))) {
115#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
116			continue;
117#else
118			best = c;
119#endif
120		}
121
122		/* From the remaining configs, choose the first one whose
123		 * first interface is for a non-vendor-specific class.
124		 * Reason: Linux is more likely to have a class driver
125		 * than a vendor-specific driver. */
126		else if (udev->descriptor.bDeviceClass !=
127						USB_CLASS_VENDOR_SPEC &&
128				(desc && desc->bInterfaceClass !=
129						USB_CLASS_VENDOR_SPEC)) {
130			best = c;
131			break;
132		}
133
134		/* If all the remaining configs are vendor-specific,
135		 * choose the first one. */
136		else if (!best)
137			best = c;
138	}
139
140	if (insufficient_power > 0)
141		dev_info(&udev->dev, "rejected %d configuration%s "
142			"due to insufficient available bus power\n",
143			insufficient_power, plural(insufficient_power));
144
145	if (best) {
146		i = best->desc.bConfigurationValue;
147		dev_dbg(&udev->dev,
148			"configuration #%d chosen from %d choice%s\n",
149			i, num_configs, plural(num_configs));
150	} else {
151		i = -1;
152		dev_warn(&udev->dev,
153			"no configuration chosen from %d choice%s\n",
154			num_configs, plural(num_configs));
155	}
156	return i;
157}
158EXPORT_SYMBOL_GPL(usb_choose_configuration);
159
160static int generic_probe(struct usb_device *udev)
161{
162	int err, c;
163
164	/* Choose and set the configuration.  This registers the interfaces
165	 * with the driver core and lets interface drivers bind to them.
166	 */
167	if (udev->authorized == 0)
168		dev_err(&udev->dev, "Device is not authorized for usage\n");
169	else {
170		c = usb_choose_configuration(udev);
171		if (c >= 0) {
172			err = usb_set_configuration(udev, c);
173			if (err && err != -ENODEV) {
174				dev_err(&udev->dev, "can't set config #%d, error %d\n",
175					c, err);
176				/* This need not be fatal.  The user can try to
177				 * set other configurations. */
178			}
179		}
180	}
181	/* USB device state == configured ... usable */
182	usb_notify_add_device(udev);
183
184	return 0;
185}
186
187static void generic_disconnect(struct usb_device *udev)
188{
189	usb_notify_remove_device(udev);
190
191	/* if this is only an unbind, not a physical disconnect, then
192	 * unconfigure the device */
193	if (udev->actconfig)
194		usb_set_configuration(udev, -1);
195}
196
197#ifdef	CONFIG_PM
198
199static int generic_suspend(struct usb_device *udev, pm_message_t msg)
200{
201	int rc;
202
203	/* Normal USB devices suspend through their upstream port.
204	 * Root hubs don't have upstream ports to suspend,
205	 * so we have to shut down their downstream HC-to-USB
206	 * interfaces manually by doing a bus (or "global") suspend.
207	 */
208	if (!udev->parent)
209		rc = hcd_bus_suspend(udev, msg);
210
211	/* Non-root devices don't need to do anything for FREEZE or PRETHAW */
212	else if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
213		rc = 0;
214	else
215		rc = usb_port_suspend(udev, msg);
216
217	return rc;
218}
219
220static int generic_resume(struct usb_device *udev, pm_message_t msg)
221{
222	int rc;
223
224	/* Normal USB devices resume/reset through their upstream port.
225	 * Root hubs don't have upstream ports to resume or reset,
226	 * so we have to start up their downstream HC-to-USB
227	 * interfaces manually by doing a bus (or "global") resume.
228	 */
229	if (!udev->parent)
230		rc = hcd_bus_resume(udev, msg);
231	else
232		rc = usb_port_resume(udev, msg);
233	return rc;
234}
235
236#endif	/* CONFIG_PM */
237
238struct usb_device_driver usb_generic_driver = {
239	.name =	"usb",
240	.probe = generic_probe,
241	.disconnect = generic_disconnect,
242#ifdef	CONFIG_PM
243	.suspend = generic_suspend,
244	.resume = generic_resume,
245#endif
246	.supports_autosuspend = 1,
247};
248