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