drivers/usb/core/generic.c

   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                 /* When the first config's first interface is one of Microsoft's
 122                  * pet nonstandard Ethernet-over-USB protocols, ignore it unless
 123                  * this kernel has enabled the necessary host side driver.
 124                  * But: Don't ignore it if it's the only config.
 125                  */
 126                 if (i == 0 && num_configs > 1 && desc &&
 127                                 (is_rndis(desc) || is_activesync(desc))) {
 128 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
 129                         continue;
 130 #else
 131                         best = c;
 132 #endif
 133                 }
 134
 135                 /*
 136                  * Select first configuration as default for audio so that
 137                  * devices that don't comply with UAC3 protocol are supported.
 138                  * But, still iterate through other configurations and
 139                  * select UAC3 compliant config if present.
 140                  */
 141                 if (i == 0 && num_configs > 1 && desc && is_audio(desc)) {
 142                         best = c;
 143                         continue;
 144                 }
 145
 146                 if (i > 0 && desc && is_audio(desc)) {
 147                         if (is_uac3_config(desc)) {
 148                                 best = c;
 149                                 break;
 150                         }
 151                         continue;
 152                 }
 153
 154                 /* From the remaining configs, choose the first one whose
 155                  * first interface is for a non-vendor-specific class.
 156                  * Reason: Linux is more likely to have a class driver
 157                  * than a vendor-specific driver. */
 158                 else if (udev->descriptor.bDeviceClass !=
 159                                                 USB_CLASS_VENDOR_SPEC &&
 160                                 (desc && desc->bInterfaceClass !=
 161                                                 USB_CLASS_VENDOR_SPEC)) {
 162                         best = c;
 163                         break;
 164                 }
 165
 166                 /* If all the remaining configs are vendor-specific,
 167                  * choose the first one. */
 168                 else if (!best)
 169                         best = c;
 170         }
 171
 172         if (insufficient_power > 0)
 173                 dev_info(&udev->dev, "rejected %d configuration%s "
 174                         "due to insufficient available bus power\n",
 175                         insufficient_power, plural(insufficient_power));
 176
 177         if (best) {
 178                 i = best->desc.bConfigurationValue;
 179                 dev_dbg(&udev->dev,
 180                         "configuration #%d chosen from %d choice%s\n",
 181                         i, num_configs, plural(num_configs));
 182         } else {
 183                 i = -1;
 184                 dev_warn(&udev->dev,
 185                         "no configuration chosen from %d choice%s\n",
 186                         num_configs, plural(num_configs));
 187         }
 188         return i;
 189 }
 190 EXPORT_SYMBOL_GPL(usb_choose_configuration);
 191
 192 static int generic_probe(struct usb_device *udev)
 193 {
 194         int err, c;
 195
 196         /* Choose and set the configuration.  This registers the interfaces
 197          * with the driver core and lets interface drivers bind to them.
 198          */
 199         if (udev->authorized == 0)
 200                 dev_err(&udev->dev, "Device is not authorized for usage\n");
 201         else {
 202                 c = usb_choose_configuration(udev);
 203                 if (c >= 0) {
 204                         err = usb_set_configuration(udev, c);
 205                         if (err && err != -ENODEV) {
 206                                 dev_err(&udev->dev, "can't set config #%d, error %d\n",
 207                                         c, err);
 208                                 /* This need not be fatal.  The user can try to
 209                                  * set other configurations. */
 210                         }
 211                 }
 212         }
 213         /* USB device state == configured ... usable */
 214         usb_notify_add_device(udev);
 215
 216         return 0;
 217 }
 218
 219 static void generic_disconnect(struct usb_device *udev)
 220 {
 221         usb_notify_remove_device(udev);
 222
 223         /* if this is only an unbind, not a physical disconnect, then
 224          * unconfigure the device */
 225         if (udev->actconfig)
 226                 usb_set_configuration(udev, -1);
 227 }
 228
 229 #ifdef  CONFIG_PM
 230
 231 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 232 {
 233         int rc;
 234
 235         /* Normal USB devices suspend through their upstream port.
 236          * Root hubs don't have upstream ports to suspend,
 237          * so we have to shut down their downstream HC-to-USB
 238          * interfaces manually by doing a bus (or "global") suspend.
 239          */
 240         if (!udev->parent)
 241                 rc = hcd_bus_suspend(udev, msg);
 242
 243         /*
 244          * Non-root USB2 devices don't need to do anything for FREEZE
 245          * or PRETHAW. USB3 devices don't support global suspend and
 246          * needs to be selectively suspended.
 247          */
 248         else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
 249                  && (udev->speed < USB_SPEED_SUPER))
 250                 rc = 0;
 251         else
 252                 rc = usb_port_suspend(udev, msg);
 253
 254         return rc;
 255 }
 256
 257 static int generic_resume(struct usb_device *udev, pm_message_t msg)
 258 {
 259         int rc;
 260
 261         /* Normal USB devices resume/reset through their upstream port.
 262          * Root hubs don't have upstream ports to resume or reset,
 263          * so we have to start up their downstream HC-to-USB
 264          * interfaces manually by doing a bus (or "global") resume.
 265          */
 266         if (!udev->parent)
 267                 rc = hcd_bus_resume(udev, msg);
 268         else
 269                 rc = usb_port_resume(udev, msg);
 270         return rc;
 271 }
 272
 273 #endif  /* CONFIG_PM */
 274
 275 struct usb_device_driver usb_generic_driver = {
 276         .name = "usb",
 277         .probe = generic_probe,
 278         .disconnect = generic_disconnect,
 279 #ifdef  CONFIG_PM
 280         .suspend = generic_suspend,
 281         .resume = generic_resume,
 282 #endif
 283         .supports_autosuspend = 1,
 284 };