1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/usb/core/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 <linux/string_choices.h>
25#include <uapi/linux/usb/audio.h>
26#include "usb.h"
27
28static int is_rndis(struct usb_interface_descriptor *desc)
29{
30 return desc->bInterfaceClass == USB_CLASS_COMM
31 && desc->bInterfaceSubClass == 2
32 && desc->bInterfaceProtocol == 0xff;
33}
34
35static int is_activesync(struct usb_interface_descriptor *desc)
36{
37 return desc->bInterfaceClass == USB_CLASS_MISC
38 && desc->bInterfaceSubClass == 1
39 && desc->bInterfaceProtocol == 1;
40}
41
42static bool is_audio(struct usb_interface_descriptor *desc)
43{
44 return desc->bInterfaceClass == USB_CLASS_AUDIO;
45}
46
47static bool is_uac3_config(struct usb_interface_descriptor *desc)
48{
49 return desc->bInterfaceProtocol == UAC_VERSION_3;
50}
51
52int usb_choose_configuration(struct usb_device *udev)
53{
54 int i;
55 int num_configs;
56 int insufficient_power = 0;
57 struct usb_host_config *c, *best;
58 struct usb_device_driver *udriver;
59
60 /*
61 * If a USB device (not an interface) doesn't have a driver then the
62 * kernel has no business trying to select or install a configuration
63 * for it.
64 */
65 if (!udev->dev.driver)
66 return -1;
67 udriver = to_usb_device_driver(udev->dev.driver);
68
69 if (usb_device_is_owned(udev))
70 return 0;
71
72 if (udriver->choose_configuration) {
73 i = udriver->choose_configuration(udev);
74 if (i >= 0)
75 return i;
76 }
77
78 best = NULL;
79 c = udev->config;
80 num_configs = udev->descriptor.bNumConfigurations;
81 for (i = 0; i < num_configs; (i++, c++)) {
82 struct usb_interface_descriptor *desc = NULL;
83
84 /* It's possible that a config has no interfaces! */
85 if (c->desc.bNumInterfaces > 0)
86 desc = &c->intf_cache[0]->altsetting->desc;
87
88 /*
89 * HP's USB bus-powered keyboard has only one configuration
90 * and it claims to be self-powered; other devices may have
91 * similar errors in their descriptors. If the next test
92 * were allowed to execute, such configurations would always
93 * be rejected and the devices would not work as expected.
94 * In the meantime, we run the risk of selecting a config
95 * that requires external power at a time when that power
96 * isn't available. It seems to be the lesser of two evils.
97 *
98 * Bugzilla #6448 reports a device that appears to crash
99 * when it receives a GET_DEVICE_STATUS request! We don't
100 * have any other way to tell whether a device is self-powered,
101 * but since we don't use that information anywhere but here,
102 * the call has been removed.
103 *
104 * Maybe the GET_DEVICE_STATUS call and the test below can
105 * be reinstated when device firmwares become more reliable.
106 * Don't hold your breath.
107 */
108#if 0
109 /* Rule out self-powered configs for a bus-powered device */
110 if (bus_powered && (c->desc.bmAttributes &
111 USB_CONFIG_ATT_SELFPOWER))
112 continue;
113#endif
114
115 /*
116 * The next test may not be as effective as it should be.
117 * Some hubs have errors in their descriptor, claiming
118 * to be self-powered when they are really bus-powered.
119 * We will overestimate the amount of current such hubs
120 * make available for each port.
121 *
122 * This is a fairly benign sort of failure. It won't
123 * cause us to reject configurations that we should have
124 * accepted.
125 */
126
127 /* Rule out configs that draw too much bus current */
128 if (usb_get_max_power(udev, c) > udev->bus_mA) {
129 insufficient_power++;
130 continue;
131 }
132
133 /*
134 * Select first configuration as default for audio so that
135 * devices that don't comply with UAC3 protocol are supported.
136 * But, still iterate through other configurations and
137 * select UAC3 compliant config if present.
138 */
139 if (desc && is_audio(desc)) {
140 /* Always prefer the first found UAC3 config */
141 if (is_uac3_config(desc)) {
142 best = c;
143 break;
144 }
145
146 /* If there is no UAC3 config, prefer the first config */
147 else if (i == 0)
148 best = c;
149
150 /* Unconditional continue, because the rest of the code
151 * in the loop is irrelevant for audio devices, and
152 * because it can reassign best, which for audio devices
153 * we don't want.
154 */
155 continue;
156 }
157
158 /* When the first config's first interface is one of Microsoft's
159 * pet nonstandard Ethernet-over-USB protocols, ignore it unless
160 * this kernel has enabled the necessary host side driver.
161 * But: Don't ignore it if it's the only config.
162 */
163 if (i == 0 && num_configs > 1 && desc &&
164 (is_rndis(desc) || is_activesync(desc))) {
165#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
166 continue;
167#else
168 best = c;
169#endif
170 }
171
172 /* From the remaining configs, choose the first one whose
173 * first interface is for a non-vendor-specific class.
174 * Reason: Linux is more likely to have a class driver
175 * than a vendor-specific driver. */
176 else if (udev->descriptor.bDeviceClass !=
177 USB_CLASS_VENDOR_SPEC &&
178 (desc && desc->bInterfaceClass !=
179 USB_CLASS_VENDOR_SPEC)) {
180 best = c;
181 break;
182 }
183
184 /* If all the remaining configs are vendor-specific,
185 * choose the first one. */
186 else if (!best)
187 best = c;
188 }
189
190 if (insufficient_power > 0)
191 dev_info(&udev->dev, "rejected %d configuration%s "
192 "due to insufficient available bus power\n",
193 insufficient_power, str_plural(insufficient_power));
194
195 if (best) {
196 i = best->desc.bConfigurationValue;
197 dev_dbg(&udev->dev,
198 "configuration #%d chosen from %d choice%s\n",
199 i, num_configs, str_plural(num_configs));
200 } else {
201 i = -1;
202 dev_warn(&udev->dev,
203 "no configuration chosen from %d choice%s\n",
204 num_configs, str_plural(num_configs));
205 }
206 return i;
207}
208EXPORT_SYMBOL_GPL(usb_choose_configuration);
209
210static int __check_for_non_generic_match(struct device_driver *drv, void *data)
211{
212 struct usb_device *udev = data;
213 struct usb_device_driver *udrv;
214
215 if (!is_usb_device_driver(drv))
216 return 0;
217 udrv = to_usb_device_driver(drv);
218 if (udrv == &usb_generic_driver)
219 return 0;
220 return usb_driver_applicable(udev, udrv);
221}
222
223static bool usb_generic_driver_match(struct usb_device *udev)
224{
225 if (udev->use_generic_driver)
226 return true;
227
228 /*
229 * If any other driver wants the device, leave the device to this other
230 * driver.
231 */
232 if (bus_for_each_drv(bus: &usb_bus_type, NULL, data: udev, fn: __check_for_non_generic_match))
233 return false;
234
235 return true;
236}
237
238int usb_generic_driver_probe(struct usb_device *udev)
239{
240 int err, c;
241
242 /* Choose and set the configuration. This registers the interfaces
243 * with the driver core and lets interface drivers bind to them.
244 */
245 if (udev->authorized == 0)
246 dev_info(&udev->dev, "Device is not authorized for usage\n");
247 else {
248 c = usb_choose_configuration(udev);
249 if (c >= 0) {
250 err = usb_set_configuration(dev: udev, configuration: c);
251 if (err && err != -ENODEV) {
252 dev_err(&udev->dev, "can't set config #%d, error %d\n",
253 c, err);
254 /* This need not be fatal. The user can try to
255 * set other configurations. */
256 }
257 }
258 }
259 /* USB device state == configured ... usable */
260 usb_notify_add_device(udev);
261
262 return 0;
263}
264
265void usb_generic_driver_disconnect(struct usb_device *udev)
266{
267 usb_notify_remove_device(udev);
268
269 /* if this is only an unbind, not a physical disconnect, then
270 * unconfigure the device */
271 if (udev->actconfig)
272 usb_set_configuration(dev: udev, configuration: -1);
273}
274
275#ifdef CONFIG_PM
276
277int usb_generic_driver_suspend(struct usb_device *udev, pm_message_t msg)
278{
279 int rc;
280
281 /* Normal USB devices suspend through their upstream port.
282 * Root hubs don't have upstream ports to suspend,
283 * so we have to shut down their downstream HC-to-USB
284 * interfaces manually by doing a bus (or "global") suspend.
285 */
286 if (!udev->parent)
287 rc = hcd_bus_suspend(rhdev: udev, msg);
288
289 /*
290 * Non-root USB2 devices don't need to do anything for FREEZE
291 * or PRETHAW. USB3 devices don't support global suspend and
292 * needs to be selectively suspended.
293 */
294 else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
295 && (udev->speed < USB_SPEED_SUPER))
296 rc = 0;
297 else
298 rc = usb_port_suspend(dev: udev, msg);
299
300 if (rc == 0)
301 usbfs_notify_suspend(udev);
302 return rc;
303}
304
305int usb_generic_driver_resume(struct usb_device *udev, pm_message_t msg)
306{
307 int rc;
308
309 /* Normal USB devices resume/reset through their upstream port.
310 * Root hubs don't have upstream ports to resume or reset,
311 * so we have to start up their downstream HC-to-USB
312 * interfaces manually by doing a bus (or "global") resume.
313 */
314 if (!udev->parent)
315 rc = hcd_bus_resume(rhdev: udev, msg);
316 else
317 rc = usb_port_resume(dev: udev, msg);
318
319 if (rc == 0)
320 usbfs_notify_resume(udev);
321 return rc;
322}
323
324#endif /* CONFIG_PM */
325
326struct usb_device_driver usb_generic_driver = {
327 .name = "usb",
328 .match = usb_generic_driver_match,
329 .probe = usb_generic_driver_probe,
330 .disconnect = usb_generic_driver_disconnect,
331#ifdef CONFIG_PM
332 .suspend = usb_generic_driver_suspend,
333 .resume = usb_generic_driver_resume,
334#endif
335 .supports_autosuspend = 1,
336};
337

source code of linux/drivers/usb/core/generic.c