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 <uapi/linux/usb/audio.h>
25 #include "usb.h"
26
27 static inline const char *plural(int n)
28 {
29 return (n == 1 ? "" : "s");
30 }
31
32 static int is_rndis(struct usb_interface_descriptor *desc)
33 {
34 return desc->bInterfaceClass == USB_CLASS_COMM
35 && desc->bInterfaceSubClass == 2
36 && desc->bInterfaceProtocol == 0xff;
37 }
38
39 static int is_activesync(struct usb_interface_descriptor *desc)
40 {
41 return desc->bInterfaceClass == USB_CLASS_MISC
42 && desc->bInterfaceSubClass == 1
43 && desc->bInterfaceProtocol == 1;
44 }
45
46 static bool is_audio(struct usb_interface_descriptor *desc)
47 {
48 return desc->bInterfaceClass == USB_CLASS_AUDIO;
49 }
50
51 static bool is_uac3_config(struct usb_interface_descriptor *desc)
52 {
53 return desc->bInterfaceProtocol == UAC_VERSION_3;
54 }
55
56 int usb_choose_configuration(struct usb_device *udev)
57 {
58 int i;
59 int num_configs;
60 int insufficient_power = 0;
61 struct usb_host_config *c, *best;
62
63 if (usb_device_is_owned(udev))
64 return 0;
65
66 best = NULL;
67 c = udev->config;
68 num_configs = udev->descriptor.bNumConfigurations;
69 for (i = 0; i < num_configs; (i++, c++)) {
70 struct usb_interface_descriptor *desc = NULL;
71
72 /* It's possible that a config has no interfaces! */
73 if (c->desc.bNumInterfaces > 0)
74 desc = &c->intf_cache[0]->altsetting->desc;
75
76 /*
77 * HP's USB bus-powered keyboard has only one configuration
78 * and it claims to be self-powered; other devices may have
79 * similar errors in their descriptors. If the next test
80 * were allowed to execute, such configurations would always
81 * be rejected and the devices would not work as expected.
82 * In the meantime, we run the risk of selecting a config
83 * that requires external power at a time when that power
84 * isn't available. It seems to be the lesser of two evils.
85 *
86 * Bugzilla #6448 reports a device that appears to crash
87 * when it receives a GET_DEVICE_STATUS request! We don't
88 * have any other way to tell whether a device is self-powered,
89 * but since we don't use that information anywhere but here,
90 * the call has been removed.
91 *
92 * Maybe the GET_DEVICE_STATUS call and the test below can
93 * be reinstated when device firmwares become more reliable.
94 * Don't hold your breath.
95 */
96 #if 0
97 /* Rule out self-powered configs for a bus-powered device */
98 if (bus_powered && (c->desc.bmAttributes &
99 USB_CONFIG_ATT_SELFPOWER))
100 continue;
101 #endif
102
103 /*
104 * The next test may not be as effective as it should be.
105 * Some hubs have errors in their descriptor, claiming
106 * to be self-powered when they are really bus-powered.
107 * We will overestimate the amount of current such hubs
108 * make available for each port.
109 *
110 * This is a fairly benign sort of failure. It won't
111 * cause us to reject configurations that we should have
112 * accepted.
113 */
114
115 /* Rule out configs that draw too much bus current */
116 if (usb_get_max_power(udev, c) > udev->bus_mA) {
117 insufficient_power++;
118 continue;
119 }
120
121 /*
122 * Select first configuration as default for audio so that
123 * devices that don't comply with UAC3 protocol are supported.
124 * But, still iterate through other configurations and
125 * select UAC3 compliant config if present.
126 */
127 if (desc && is_audio(desc)) {
128 /* Always prefer the first found UAC3 config */
129 if (is_uac3_config(desc)) {
130 best = c;
131 break;
132 }
133
134 /* If there is no UAC3 config, prefer the first config */
135 else if (i == 0)
136 best = c;
137
138 /* Unconditional continue, because the rest of the code
139 * in the loop is irrelevant for audio devices, and
140 * because it can reassign best, which for audio devices
141 * we don't want.
142 */
143 continue;
144 }
145
146 /* When the first config's first interface is one of Microsoft's
147 * pet nonstandard Ethernet-over-USB protocols, ignore it unless
148 * this kernel has enabled the necessary host side driver.
149 * But: Don't ignore it if it's the only config.
150 */
151 if (i == 0 && num_configs > 1 && desc &&
152 (is_rndis(desc) || is_activesync(desc))) {
153 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
154 continue;
155 #else
156 best = c;
157 #endif
158 }
159
160 /* From the remaining configs, choose the first one whose
161 * first interface is for a non-vendor-specific class.
162 * Reason: Linux is more likely to have a class driver
163 * than a vendor-specific driver. */
164 else if (udev->descriptor.bDeviceClass !=
165 USB_CLASS_VENDOR_SPEC &&
166 (desc && desc->bInterfaceClass !=
167 USB_CLASS_VENDOR_SPEC)) {
168 best = c;
169 break;
170 }
171
172 /* If all the remaining configs are vendor-specific,
173 * choose the first one. */
174 else if (!best)
175 best = c;
176 }
177
178 if (insufficient_power > 0)
179 dev_info(&udev->dev, "rejected %d configuration%s "
180 "due to insufficient available bus power\n",
181 insufficient_power, plural(insufficient_power));
182
183 if (best) {
184 i = best->desc.bConfigurationValue;
185 dev_dbg(&udev->dev,
186 "configuration #%d chosen from %d choice%s\n",
187 i, num_configs, plural(num_configs));
188 } else {
189 i = -1;
190 dev_warn(&udev->dev,
191 "no configuration chosen from %d choice%s\n",
192 num_configs, plural(num_configs));
193 }
194 return i;
195 }
196 EXPORT_SYMBOL_GPL(usb_choose_configuration);
197
198 static int generic_probe(struct usb_device *udev)
199 {
200 int err, c;
201
202 /* Choose and set the configuration. This registers the interfaces
203 * with the driver core and lets interface drivers bind to them.
204 */
205 if (udev->authorized == 0)
206 dev_err(&udev->dev, "Device is not authorized for usage\n");
207 else {
208 c = usb_choose_configuration(udev);
209 if (c >= 0) {
210 err = usb_set_configuration(udev, c);
211 if (err && err != -ENODEV) {
212 dev_err(&udev->dev, "can't set config #%d, error %d\n",
213 c, err);
214 /* This need not be fatal. The user can try to
215 * set other configurations. */
216 }
217 }
218 }
219 /* USB device state == configured ... usable */
220 usb_notify_add_device(udev);
221
222 return 0;
223 }
224
225 static void generic_disconnect(struct usb_device *udev)
226 {
227 usb_notify_remove_device(udev);
228
229 /* if this is only an unbind, not a physical disconnect, then
230 * unconfigure the device */
231 if (udev->actconfig)
232 usb_set_configuration(udev, -1);
233 }
234
235 #ifdef CONFIG_PM
236
237 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
238 {
239 int rc;
240
241 /* Normal USB devices suspend through their upstream port.
242 * Root hubs don't have upstream ports to suspend,
243 * so we have to shut down their downstream HC-to-USB
244 * interfaces manually by doing a bus (or "global") suspend.
245 */
246 if (!udev->parent)
247 rc = hcd_bus_suspend(udev, msg);
248
249 /*
250 * Non-root USB2 devices don't need to do anything for FREEZE
251 * or PRETHAW. USB3 devices don't support global suspend and
252 * needs to be selectively suspended.
253 */
254 else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
255 && (udev->speed < USB_SPEED_SUPER))
256 rc = 0;
257 else
258 rc = usb_port_suspend(udev, msg);
259
260 if (rc == 0)
261 usbfs_notify_suspend(udev);
262 return rc;
263 }
264
265 static int generic_resume(struct usb_device *udev, pm_message_t msg)
266 {
267 int rc;
268
269 /* Normal USB devices resume/reset through their upstream port.
270 * Root hubs don't have upstream ports to resume or reset,
271 * so we have to start up their downstream HC-to-USB
272 * interfaces manually by doing a bus (or "global") resume.
273 */
274 if (!udev->parent)
275 rc = hcd_bus_resume(udev, msg);
276 else
277 rc = usb_port_resume(udev, msg);
278
279 if (rc == 0)
280 usbfs_notify_resume(udev);
281 return rc;
282 }
283
284 #endif /* CONFIG_PM */
285
286 struct usb_device_driver usb_generic_driver = {
287 .name = "usb",
288 .probe = generic_probe,
289 .disconnect = generic_disconnect,
290 #ifdef CONFIG_PM
291 .suspend = generic_suspend,
292 .resume = generic_resume,
293 #endif
294 .supports_autosuspend = 1,
295 };