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 "usb.h"
  25
  26 static inline const char *plural(int n)
  27 {
  28         return (n == 1 ? "" : "s");
  29 }
  30
  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
  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
  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
 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
 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
 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
 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 };