drivers/usb/core/generic.c

   1 /*
   2  * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
   3  *
   4  * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
   5  *
   6  * based on drivers/usb/usb.c which had the following copyrights:
   7  *      (C) Copyright Linus Torvalds 1999
   8  *      (C) Copyright Johannes Erdfelt 1999-2001
   9  *      (C) Copyright Andreas Gal 1999
  10  *      (C) Copyright Gregory P. Smith 1999
  11  *      (C) Copyright Deti Fliegl 1999 (new USB architecture)
  12  *      (C) Copyright Randy Dunlap 2000
  13  *      (C) Copyright David Brownell 2000-2004
  14  *      (C) Copyright Yggdrasil Computing, Inc. 2000
  15  *              (usb_device_id matching changes by Adam J. Richter)
  16  *      (C) Copyright Greg Kroah-Hartman 2002-2003
  17  *
  18  */
  19
  20 #include <linux/usb.h>
  21 #include <linux/usb/hcd.h>
  22 #include "usb.h"
  23
  24 static inline const char *plural(int n)
  25 {
  26         return (n == 1 ? "" : "s");
  27 }
  28
  29 static int is_rndis(struct usb_interface_descriptor *desc)
  30 {
  31         return desc->bInterfaceClass == USB_CLASS_COMM
  32                 && desc->bInterfaceSubClass == 2
  33                 && desc->bInterfaceProtocol == 0xff;
  34 }
  35
  36 static int is_activesync(struct usb_interface_descriptor *desc)
  37 {
  38         return desc->bInterfaceClass == USB_CLASS_MISC
  39                 && desc->bInterfaceSubClass == 1
  40                 && desc->bInterfaceProtocol == 1;
  41 }
  42
  43 int usb_choose_configuration(struct usb_device *udev)
  44 {
  45         int i;
  46         int num_configs;
  47         int insufficient_power = 0;
  48         struct usb_host_config *c, *best;
  49
  50         if (usb_device_is_owned(udev))
  51                 return 0;
  52
  53         best = NULL;
  54         c = udev->config;
  55         num_configs = udev->descriptor.bNumConfigurations;
  56         for (i = 0; i < num_configs; (i++, c++)) {
  57                 struct usb_interface_descriptor *desc = NULL;
  58
  59                 /* It's possible that a config has no interfaces! */
  60                 if (c->desc.bNumInterfaces > 0)
  61                         desc = &c->intf_cache[0]->altsetting->desc;
  62
  63                 /*
  64                  * HP's USB bus-powered keyboard has only one configuration
  65                  * and it claims to be self-powered; other devices may have
  66                  * similar errors in their descriptors.  If the next test
  67                  * were allowed to execute, such configurations would always
  68                  * be rejected and the devices would not work as expected.
  69                  * In the meantime, we run the risk of selecting a config
  70                  * that requires external power at a time when that power
  71                  * isn't available.  It seems to be the lesser of two evils.
  72                  *
  73                  * Bugzilla #6448 reports a device that appears to crash
  74                  * when it receives a GET_DEVICE_STATUS request!  We don't
  75                  * have any other way to tell whether a device is self-powered,
  76                  * but since we don't use that information anywhere but here,
  77                  * the call has been removed.
  78                  *
  79                  * Maybe the GET_DEVICE_STATUS call and the test below can
  80                  * be reinstated when device firmwares become more reliable.
  81                  * Don't hold your breath.
  82                  */
  83 #if 0
  84                 /* Rule out self-powered configs for a bus-powered device */
  85                 if (bus_powered && (c->desc.bmAttributes &
  86                                         USB_CONFIG_ATT_SELFPOWER))
  87                         continue;
  88 #endif
  89
  90                 /*
  91                  * The next test may not be as effective as it should be.
  92                  * Some hubs have errors in their descriptor, claiming
  93                  * to be self-powered when they are really bus-powered.
  94                  * We will overestimate the amount of current such hubs
  95                  * make available for each port.
  96                  *
  97                  * This is a fairly benign sort of failure.  It won't
  98                  * cause us to reject configurations that we should have
  99                  * accepted.
 100                  */
 101
 102                 /* Rule out configs that draw too much bus current */
 103                 if (c->desc.bMaxPower * 2 > udev->bus_mA) {
 104                         insufficient_power++;
 105                         continue;
 106                 }
 107
 108                 /* When the first config's first interface is one of Microsoft's
 109                  * pet nonstandard Ethernet-over-USB protocols, ignore it unless
 110                  * this kernel has enabled the necessary host side driver.
 111                  * But: Don't ignore it if it's the only config.
 112                  */
 113                 if (i == 0 && num_configs > 1 && desc &&
 114                                 (is_rndis(desc) || is_activesync(desc))) {
 115 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
 116                         continue;
 117 #else
 118                         best = c;
 119 #endif
 120                 }
 121
 122                 /* From the remaining configs, choose the first one whose
 123                  * first interface is for a non-vendor-specific class.
 124                  * Reason: Linux is more likely to have a class driver
 125                  * than a vendor-specific driver. */
 126                 else if (udev->descriptor.bDeviceClass !=
 127                                                 USB_CLASS_VENDOR_SPEC &&
 128                                 (desc && desc->bInterfaceClass !=
 129                                                 USB_CLASS_VENDOR_SPEC)) {
 130                         best = c;
 131                         break;
 132                 }
 133
 134                 /* If all the remaining configs are vendor-specific,
 135                  * choose the first one. */
 136                 else if (!best)
 137                         best = c;
 138         }
 139
 140         if (insufficient_power > 0)
 141                 dev_info(&udev->dev, "rejected %d configuration%s "
 142                         "due to insufficient available bus power\n",
 143                         insufficient_power, plural(insufficient_power));
 144
 145         if (best) {
 146                 i = best->desc.bConfigurationValue;
 147                 dev_dbg(&udev->dev,
 148                         "configuration #%d chosen from %d choice%s\n",
 149                         i, num_configs, plural(num_configs));
 150         } else {
 151                 i = -1;
 152                 dev_warn(&udev->dev,
 153                         "no configuration chosen from %d choice%s\n",
 154                         num_configs, plural(num_configs));
 155         }
 156         return i;
 157 }
 158
 159 static int generic_probe(struct usb_device *udev)
 160 {
 161         int err, c;
 162
 163         /* Choose and set the configuration.  This registers the interfaces
 164          * with the driver core and lets interface drivers bind to them.
 165          */
 166         if (udev->authorized == 0)
 167                 dev_err(&udev->dev, "Device is not authorized for usage\n");
 168         else {
 169                 c = usb_choose_configuration(udev);
 170                 if (c >= 0) {
 171                         err = usb_set_configuration(udev, c);
 172                         if (err) {
 173                                 dev_err(&udev->dev, "can't set config #%d, error %d\n",
 174                                         c, err);
 175                                 /* This need not be fatal.  The user can try to
 176                                  * set other configurations. */
 177                         }
 178                 }
 179         }
 180         /* USB device state == configured ... usable */
 181         usb_notify_add_device(udev);
 182
 183         return 0;
 184 }
 185
 186 static void generic_disconnect(struct usb_device *udev)
 187 {
 188         usb_notify_remove_device(udev);
 189
 190         /* if this is only an unbind, not a physical disconnect, then
 191          * unconfigure the device */
 192         if (udev->actconfig)
 193                 usb_set_configuration(udev, -1);
 194 }
 195
 196 #ifdef  CONFIG_PM
 197
 198 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 199 {
 200         int rc;
 201
 202         /* Normal USB devices suspend through their upstream port.
 203          * Root hubs don't have upstream ports to suspend,
 204          * so we have to shut down their downstream HC-to-USB
 205          * interfaces manually by doing a bus (or "global") suspend.
 206          */
 207         if (!udev->parent)
 208                 rc = hcd_bus_suspend(udev, msg);
 209
 210         /* Non-root devices don't need to do anything for FREEZE or PRETHAW */
 211         else if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
 212                 rc = 0;
 213         else
 214                 rc = usb_port_suspend(udev, msg);
 215
 216         return rc;
 217 }
 218
 219 static int generic_resume(struct usb_device *udev, pm_message_t msg)
 220 {
 221         int rc;
 222
 223         /* Normal USB devices resume/reset through their upstream port.
 224          * Root hubs don't have upstream ports to resume or reset,
 225          * so we have to start up their downstream HC-to-USB
 226          * interfaces manually by doing a bus (or "global") resume.
 227          */
 228         if (!udev->parent)
 229                 rc = hcd_bus_resume(udev, msg);
 230         else
 231                 rc = usb_port_resume(udev, msg);
 232         return rc;
 233 }
 234
 235 #endif  /* CONFIG_PM */
 236
 237 struct usb_device_driver usb_generic_driver = {
 238         .name = "usb",
 239         .probe = generic_probe,
 240         .disconnect = generic_disconnect,
 241 #ifdef  CONFIG_PM
 242         .suspend = generic_suspend,
 243         .resume = generic_resume,
 244 #endif
 245         .supports_autosuspend = 1,
 246 };