xref: /linux/drivers/usb/core/generic.c (revision cc8b10fa70682218c2a318fc44f71f3175a23cc0)
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 
28 static 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 
35 static 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 
42 static bool is_audio(struct usb_interface_descriptor *desc)
43 {
44 	return desc->bInterfaceClass == USB_CLASS_AUDIO;
45 }
46 
47 static bool is_uac3_config(struct usb_interface_descriptor *desc)
48 {
49 	return desc->bInterfaceProtocol == UAC_VERSION_3;
50 }
51 
52 int 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 }
208 EXPORT_SYMBOL_GPL(usb_choose_configuration);
209 
210 static 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 
223 static 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(&usb_bus_type, NULL, udev, __check_for_non_generic_match))
233 		return false;
234 
235 	return true;
236 }
237 
238 int 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_err(&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(udev, 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 
265 void 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(udev, -1);
273 }
274 
275 #ifdef	CONFIG_PM
276 
277 int 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(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(udev, msg);
299 
300 	if (rc == 0)
301 		usbfs_notify_suspend(udev);
302 	return rc;
303 }
304 
305 int 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(udev, msg);
316 	else
317 		rc = usb_port_resume(udev, msg);
318 
319 	if (rc == 0)
320 		usbfs_notify_resume(udev);
321 	return rc;
322 }
323 
324 #endif	/* CONFIG_PM */
325 
326 struct 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