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 "usb.h"
  22
  23 static inline const char *plural(int n)
  24 {
  25         return (n == 1 ? "" : "s");
  26 }
  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 int choose_configuration(struct usb_device *udev)
  43 {
  44         int i;
  45         int num_configs;
  46         int insufficient_power = 0;
  47         struct usb_host_config *c, *best;
  48
  49         best = NULL;
  50         c = udev->config;
  51         num_configs = udev->descriptor.bNumConfigurations;
  52         for (i = 0; i < num_configs; (i++, c++)) {
  53                 struct usb_interface_descriptor *desc = NULL;
  54
  55                 /* It's possible that a config has no interfaces! */
  56                 if (c->desc.bNumInterfaces > 0)
  57                         desc = &c->intf_cache[0]->altsetting->desc;
  58
  59                 /*
  60                  * HP's USB bus-powered keyboard has only one configuration
  61                  * and it claims to be self-powered; other devices may have
  62                  * similar errors in their descriptors.  If the next test
  63                  * were allowed to execute, such configurations would always
  64                  * be rejected and the devices would not work as expected.
  65                  * In the meantime, we run the risk of selecting a config
  66                  * that requires external power at a time when that power
  67                  * isn't available.  It seems to be the lesser of two evils.
  68                  *
  69                  * Bugzilla #6448 reports a device that appears to crash
  70                  * when it receives a GET_DEVICE_STATUS request!  We don't
  71                  * have any other way to tell whether a device is self-powered,
  72                  * but since we don't use that information anywhere but here,
  73                  * the call has been removed.
  74                  *
  75                  * Maybe the GET_DEVICE_STATUS call and the test below can
  76                  * be reinstated when device firmwares become more reliable.
  77                  * Don't hold your breath.
  78                  */
  79 #if 0
  80                 /* Rule out self-powered configs for a bus-powered device */
  81                 if (bus_powered && (c->desc.bmAttributes &
  82                                         USB_CONFIG_ATT_SELFPOWER))
  83                         continue;
  84 #endif
  85
  86                 /*
  87                  * The next test may not be as effective as it should be.
  88                  * Some hubs have errors in their descriptor, claiming
  89                  * to be self-powered when they are really bus-powered.
  90                  * We will overestimate the amount of current such hubs
  91                  * make available for each port.
  92                  *
  93                  * This is a fairly benign sort of failure.  It won't
  94                  * cause us to reject configurations that we should have
  95                  * accepted.
  96                  */
  97
  98                 /* Rule out configs that draw too much bus current */
  99                 if (c->desc.bMaxPower * 2 > udev->bus_mA) {
 100                         insufficient_power++;
 101                         continue;
 102                 }
 103
 104                 /* When the first config's first interface is one of Microsoft's
 105                  * pet nonstandard Ethernet-over-USB protocols, ignore it unless
 106                  * this kernel has enabled the necessary host side driver.
 107                  */
 108                 if (i == 0 && desc && (is_rndis(desc) || is_activesync(desc))) {
 109 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
 110                         continue;
 111 #else
 112                         best = c;
 113 #endif
 114                 }
 115
 116                 /* From the remaining configs, choose the first one whose
 117                  * first interface is for a non-vendor-specific class.
 118                  * Reason: Linux is more likely to have a class driver
 119                  * than a vendor-specific driver. */
 120                 else if (udev->descriptor.bDeviceClass !=
 121                                                 USB_CLASS_VENDOR_SPEC &&
 122                                 (!desc || desc->bInterfaceClass !=
 123                                                 USB_CLASS_VENDOR_SPEC)) {
 124                         best = c;
 125                         break;
 126                 }
 127
 128                 /* If all the remaining configs are vendor-specific,
 129                  * choose the first one. */
 130                 else if (!best)
 131                         best = c;
 132         }
 133
 134         if (insufficient_power > 0)
 135                 dev_info(&udev->dev, "rejected %d configuration%s "
 136                         "due to insufficient available bus power\n",
 137                         insufficient_power, plural(insufficient_power));
 138
 139         if (best) {
 140                 i = best->desc.bConfigurationValue;
 141                 dev_info(&udev->dev,
 142                         "configuration #%d chosen from %d choice%s\n",
 143                         i, num_configs, plural(num_configs));
 144         } else {
 145                 i = -1;
 146                 dev_warn(&udev->dev,
 147                         "no configuration chosen from %d choice%s\n",
 148                         num_configs, plural(num_configs));
 149         }
 150         return i;
 151 }
 152
 153 static int generic_probe(struct usb_device *udev)
 154 {
 155         int err, c;
 156
 157         /* put device-specific files into sysfs */
 158         usb_create_sysfs_dev_files(udev);
 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         c = choose_configuration(udev);
 164         if (c >= 0) {
 165                 err = usb_set_configuration(udev, c);
 166                 if (err) {
 167                         dev_err(&udev->dev, "can't set config #%d, error %d\n",
 168                                         c, err);
 169                         /* This need not be fatal.  The user can try to
 170                          * set other configurations. */
 171                 }
 172         }
 173
 174         /* USB device state == configured ... usable */
 175         usb_notify_add_device(udev);
 176
 177         return 0;
 178 }
 179
 180 static void generic_disconnect(struct usb_device *udev)
 181 {
 182         usb_notify_remove_device(udev);
 183
 184         /* if this is only an unbind, not a physical disconnect, then
 185          * unconfigure the device */
 186         if (udev->actconfig)
 187                 usb_set_configuration(udev, -1);
 188
 189         usb_remove_sysfs_dev_files(udev);
 190 }
 191
 192 #ifdef  CONFIG_PM
 193
 194 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 195 {
 196         /* USB devices enter SUSPEND state through their hubs, but can be
 197          * marked for FREEZE as soon as their children are already idled.
 198          * But those semantics are useless, so we equate the two (sigh).
 199          */
 200         return usb_port_suspend(udev);
 201 }
 202
 203 static int generic_resume(struct usb_device *udev)
 204 {
 205         return usb_port_resume(udev);
 206 }
 207
 208 #endif  /* CONFIG_PM */
 209
 210 struct usb_device_driver usb_generic_driver = {
 211         .name = "usb",
 212         .probe = generic_probe,
 213         .disconnect = generic_disconnect,
 214 #ifdef  CONFIG_PM
 215         .suspend = generic_suspend,
 216         .resume = generic_resume,
 217 #endif
 218         .supports_autosuspend = 1,
 219 };