aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/usb/core/generic.c
blob: b6dacd7551d2e0d843a3d6998bf67a2a4b838ba6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
/*
 * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
 *
 * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
 *
 * based on drivers/usb/usb.c which had the following copyrights:
 *	(C) Copyright Linus Torvalds 1999
 *	(C) Copyright Johannes Erdfelt 1999-2001
 *	(C) Copyright Andreas Gal 1999
 *	(C) Copyright Gregory P. Smith 1999
 *	(C) Copyright Deti Fliegl 1999 (new USB architecture)
 *	(C) Copyright Randy Dunlap 2000
 *	(C) Copyright David Brownell 2000-2004
 *	(C) Copyright Yggdrasil Computing, Inc. 2000
 *		(usb_device_id matching changes by Adam J. Richter)
 *	(C) Copyright Greg Kroah-Hartman 2002-2003
 *
 */

#include <linux/config.h>
#include <linux/usb.h>
#include "usb.h"

static inline const char *plural(int n)
{
	return (n == 1 ? "" : "s");
}

static int choose_configuration(struct usb_device *udev)
{
	int i;
	int num_configs;
	int insufficient_power = 0;
	struct usb_host_config *c, *best;

	best = NULL;
	c = udev->config;
	num_configs = udev->descriptor.bNumConfigurations;
	for (i = 0; i < num_configs; (i++, c++)) {
		struct usb_interface_descriptor	*desc = NULL;

		/* It's possible that a config has no interfaces! */
		if (c->desc.bNumInterfaces > 0)
			desc = &c->intf_cache[0]->altsetting->desc;

		/*
		 * HP's USB bus-powered keyboard has only one configuration
		 * and it claims to be self-powered; other devices may have
		 * similar errors in their descriptors.  If the next test
		 * were allowed to execute, such configurations would always
		 * be rejected and the devices would not work as expected.
		 * In the meantime, we run the risk of selecting a config
		 * that requires external power at a time when that power
		 * isn't available.  It seems to be the lesser of two evils.
		 *
		 * Bugzilla #6448 reports a device that appears to crash
		 * when it receives a GET_DEVICE_STATUS request!  We don't
		 * have any other way to tell whether a device is self-powered,
		 * but since we don't use that information anywhere but here,
		 * the call has been removed.
		 *
		 * Maybe the GET_DEVICE_STATUS call and the test below can
		 * be reinstated when device firmwares become more reliable.
		 * Don't hold your breath.
		 */
#if 0
		/* Rule out self-powered configs for a bus-powered device */
		if (bus_powered && (c->desc.bmAttributes &
					USB_CONFIG_ATT_SELFPOWER))
			continue;
#endif

		/*
		 * The next test may not be as effective as it should be.
		 * Some hubs have errors in their descriptor, claiming
		 * to be self-powered when they are really bus-powered.
		 * We will overestimate the amount of current such hubs
		 * make available for each port.
		 *
		 * This is a fairly benign sort of failure.  It won't
		 * cause us to reject configurations that we should have
		 * accepted.
		 */

		/* Rule out configs that draw too much bus current */
		if (c->desc.bMaxPower * 2 > udev->bus_mA) {
			insufficient_power++;
			continue;
		}

		/* If the first config's first interface is COMM/2/0xff
		 * (MSFT RNDIS), rule it out unless Linux has host-side
		 * RNDIS support. */
		if (i == 0 && desc
				&& desc->bInterfaceClass == USB_CLASS_COMM
				&& desc->bInterfaceSubClass == 2
				&& desc->bInterfaceProtocol == 0xff) {
#ifndef CONFIG_USB_NET_RNDIS_HOST
			continue;
#else
			best = c;
#endif
		}

		/* From the remaining configs, choose the first one whose
		 * first interface is for a non-vendor-specific class.
		 * Reason: Linux is more likely to have a class driver
		 * than a vendor-specific driver. */
		else if (udev->descriptor.bDeviceClass !=
						USB_CLASS_VENDOR_SPEC &&
				(!desc || desc->bInterfaceClass !=
						USB_CLASS_VENDOR_SPEC)) {
			best = c;
			break;
		}

		/* If all the remaining configs are vendor-specific,
		 * choose the first one. */
		else if (!best)
			best = c;
	}

	if (insufficient_power > 0)
		dev_info(&udev->dev, "rejected %d configuration%s "
			"due to insufficient available bus power\n",
			insufficient_power, plural(insufficient_power));

	if (best) {
		i = best->desc.bConfigurationValue;
		dev_info(&udev->dev,
			"configuration #%d chosen from %d choice%s\n",
			i, num_configs, plural(num_configs));
	} else {
		i = -1;
		dev_warn(&udev->dev,
			"no configuration chosen from %d choice%s\n",
			num_configs, plural(num_configs));
	}
	return i;
}

static int generic_probe(struct usb_device *udev)
{
	int err, c;

	/* put device-specific files into sysfs */
	usb_create_sysfs_dev_files(udev);

	/* Choose and set the configuration.  This registers the interfaces
	 * with the driver core and lets interface drivers bind to them.
	 */
	c = choose_configuration(udev);
	if (c >= 0) {
		err = usb_set_configuration(udev, c);
		if (err) {
			dev_err(&udev->dev, "can't set config #%d, error %d\n",
					c, err);
			/* This need not be fatal.  The user can try to
			 * set other configurations. */
		}
	}

	/* USB device state == configured ... usable */
	usb_notify_add_device(udev);

	return 0;
}

static void generic_disconnect(struct usb_device *udev)
{
	usb_notify_remove_device(udev);

	/* if this is only an unbind, not a physical disconnect, then
	 * unconfigure the device */
	if (udev->state == USB_STATE_CONFIGURED)
		usb_set_configuration(udev, 0);

	usb_remove_sysfs_dev_files(udev);

	/* in case the call failed or the device was suspended */
	if (udev->state >= USB_STATE_CONFIGURED)
		usb_disable_device(udev, 0);
}

#ifdef	CONFIG_PM

static int generic_suspend(struct usb_device *udev, pm_message_t msg)
{
	/* USB devices enter SUSPEND state through their hubs, but can be
	 * marked for FREEZE as soon as their children are already idled.
	 * But those semantics are useless, so we equate the two (sigh).
	 */
	return usb_port_suspend(udev);
}

static int generic_resume(struct usb_device *udev)
{
	if (udev->state == USB_STATE_NOTATTACHED)
		return 0;

	return usb_port_resume(udev);
}

#endif	/* CONFIG_PM */

struct usb_device_driver usb_generic_driver = {
	.name =	"usb",
	.probe = generic_probe,
	.disconnect = generic_disconnect,
#ifdef	CONFIG_PM
	.suspend = generic_suspend,
	.resume = generic_resume,
#endif
};