1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
4 *
5 * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
6 *
7 * based on drivers/usb/usb.c which had the following copyrights:
8 * (C) Copyright Linus Torvalds 1999
9 * (C) Copyright Johannes Erdfelt 1999-2001
10 * (C) Copyright Andreas Gal 1999
11 * (C) Copyright Gregory P. Smith 1999
12 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
13 * (C) Copyright Randy Dunlap 2000
14 * (C) Copyright David Brownell 2000-2004
15 * (C) Copyright Yggdrasil Computing, Inc. 2000
16 * (usb_device_id matching changes by Adam J. Richter)
17 * (C) Copyright Greg Kroah-Hartman 2002-2003
18 *
19 * Released under the GPLv2 only.
20 */
21
22 #include <linux/usb.h>
23 #include <linux/usb/hcd.h>
24 #include "usb.h"
25
plural(int n)26 static inline const char *plural(int n)
27 {
28 return (n == 1 ? "" : "s");
29 }
30
is_rndis(struct usb_interface_descriptor * desc)31 static int is_rndis(struct usb_interface_descriptor *desc)
32 {
33 return desc->bInterfaceClass == USB_CLASS_COMM
34 && desc->bInterfaceSubClass == 2
35 && desc->bInterfaceProtocol == 0xff;
36 }
37
is_activesync(struct usb_interface_descriptor * desc)38 static int is_activesync(struct usb_interface_descriptor *desc)
39 {
40 return desc->bInterfaceClass == USB_CLASS_MISC
41 && desc->bInterfaceSubClass == 1
42 && desc->bInterfaceProtocol == 1;
43 }
44
usb_choose_configuration(struct usb_device * udev)45 int usb_choose_configuration(struct usb_device *udev)
46 {
47 int i;
48 int num_configs;
49 int insufficient_power = 0;
50 struct usb_host_config *c, *best;
51
52 if (usb_device_is_owned(udev))
53 return 0;
54
55 best = NULL;
56 c = udev->config;
57 num_configs = udev->descriptor.bNumConfigurations;
58 for (i = 0; i < num_configs; (i++, c++)) {
59 struct usb_interface_descriptor *desc = NULL;
60
61 /* It's possible that a config has no interfaces! */
62 if (c->desc.bNumInterfaces > 0)
63 desc = &c->intf_cache[0]->altsetting->desc;
64
65 /*
66 * HP's USB bus-powered keyboard has only one configuration
67 * and it claims to be self-powered; other devices may have
68 * similar errors in their descriptors. If the next test
69 * were allowed to execute, such configurations would always
70 * be rejected and the devices would not work as expected.
71 * In the meantime, we run the risk of selecting a config
72 * that requires external power at a time when that power
73 * isn't available. It seems to be the lesser of two evils.
74 *
75 * Bugzilla #6448 reports a device that appears to crash
76 * when it receives a GET_DEVICE_STATUS request! We don't
77 * have any other way to tell whether a device is self-powered,
78 * but since we don't use that information anywhere but here,
79 * the call has been removed.
80 *
81 * Maybe the GET_DEVICE_STATUS call and the test below can
82 * be reinstated when device firmwares become more reliable.
83 * Don't hold your breath.
84 */
85 #if 0
86 /* Rule out self-powered configs for a bus-powered device */
87 if (bus_powered && (c->desc.bmAttributes &
88 USB_CONFIG_ATT_SELFPOWER))
89 continue;
90 #endif
91
92 /*
93 * The next test may not be as effective as it should be.
94 * Some hubs have errors in their descriptor, claiming
95 * to be self-powered when they are really bus-powered.
96 * We will overestimate the amount of current such hubs
97 * make available for each port.
98 *
99 * This is a fairly benign sort of failure. It won't
100 * cause us to reject configurations that we should have
101 * accepted.
102 */
103
104 /* Rule out configs that draw too much bus current */
105 if (usb_get_max_power(udev, c) > udev->bus_mA) {
106 insufficient_power++;
107 continue;
108 }
109
110 /* When the first config's first interface is one of Microsoft's
111 * pet nonstandard Ethernet-over-USB protocols, ignore it unless
112 * this kernel has enabled the necessary host side driver.
113 * But: Don't ignore it if it's the only config.
114 */
115 if (i == 0 && num_configs > 1 && desc &&
116 (is_rndis(desc) || is_activesync(desc))) {
117 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
118 continue;
119 #else
120 best = c;
121 #endif
122 }
123
124 /* From the remaining configs, choose the first one whose
125 * first interface is for a non-vendor-specific class.
126 * Reason: Linux is more likely to have a class driver
127 * than a vendor-specific driver. */
128 else if (udev->descriptor.bDeviceClass !=
129 USB_CLASS_VENDOR_SPEC &&
130 (desc && desc->bInterfaceClass !=
131 USB_CLASS_VENDOR_SPEC)) {
132 best = c;
133 break;
134 }
135
136 /* If all the remaining configs are vendor-specific,
137 * choose the first one. */
138 else if (!best)
139 best = c;
140 }
141
142 if (insufficient_power > 0)
143 dev_info(&udev->dev, "rejected %d configuration%s "
144 "due to insufficient available bus power\n",
145 insufficient_power, plural(insufficient_power));
146
147 if (best) {
148 i = best->desc.bConfigurationValue;
149 dev_dbg(&udev->dev,
150 "configuration #%d chosen from %d choice%s\n",
151 i, num_configs, plural(num_configs));
152 } else {
153 i = -1;
154 dev_warn(&udev->dev,
155 "no configuration chosen from %d choice%s\n",
156 num_configs, plural(num_configs));
157 }
158 return i;
159 }
160 EXPORT_SYMBOL_GPL(usb_choose_configuration);
161
generic_probe(struct usb_device * udev)162 static int generic_probe(struct usb_device *udev)
163 {
164 int err, c;
165
166 /* Choose and set the configuration. This registers the interfaces
167 * with the driver core and lets interface drivers bind to them.
168 */
169 if (udev->authorized == 0)
170 dev_err(&udev->dev, "Device is not authorized for usage\n");
171 else {
172 c = usb_choose_configuration(udev);
173 if (c >= 0) {
174 err = usb_set_configuration(udev, c);
175 if (err && err != -ENODEV) {
176 dev_err(&udev->dev, "can't set config #%d, error %d\n",
177 c, err);
178 /* This need not be fatal. The user can try to
179 * set other configurations. */
180 }
181 }
182 }
183 /* USB device state == configured ... usable */
184 usb_notify_add_device(udev);
185
186 return 0;
187 }
188
generic_disconnect(struct usb_device * udev)189 static void generic_disconnect(struct usb_device *udev)
190 {
191 usb_notify_remove_device(udev);
192
193 /* if this is only an unbind, not a physical disconnect, then
194 * unconfigure the device */
195 if (udev->actconfig)
196 usb_set_configuration(udev, -1);
197 }
198
199 #ifdef CONFIG_PM
200
generic_suspend(struct usb_device * udev,pm_message_t msg)201 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
202 {
203 int rc;
204
205 /* Normal USB devices suspend through their upstream port.
206 * Root hubs don't have upstream ports to suspend,
207 * so we have to shut down their downstream HC-to-USB
208 * interfaces manually by doing a bus (or "global") suspend.
209 */
210 if (!udev->parent)
211 rc = hcd_bus_suspend(udev, msg);
212
213 /*
214 * Non-root USB2 devices don't need to do anything for FREEZE
215 * or PRETHAW. USB3 devices don't support global suspend and
216 * needs to be selectively suspended.
217 */
218 else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
219 && (udev->speed < USB_SPEED_SUPER))
220 rc = 0;
221 else
222 rc = usb_port_suspend(udev, msg);
223
224 return rc;
225 }
226
generic_resume(struct usb_device * udev,pm_message_t msg)227 static int generic_resume(struct usb_device *udev, pm_message_t msg)
228 {
229 int rc;
230
231 /* Normal USB devices resume/reset through their upstream port.
232 * Root hubs don't have upstream ports to resume or reset,
233 * so we have to start up their downstream HC-to-USB
234 * interfaces manually by doing a bus (or "global") resume.
235 */
236 if (!udev->parent)
237 rc = hcd_bus_resume(udev, msg);
238 else
239 rc = usb_port_resume(udev, msg);
240 return rc;
241 }
242
243 #endif /* CONFIG_PM */
244
245 struct usb_device_driver usb_generic_driver = {
246 .name = "usb",
247 .probe = generic_probe,
248 .disconnect = generic_disconnect,
249 #ifdef CONFIG_PM
250 .suspend = generic_suspend,
251 .resume = generic_resume,
252 #endif
253 .supports_autosuspend = 1,
254 };
255
