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 #include "hcd.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 static int 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                  */
 109                 if (i == 0 && desc && (is_rndis(desc) || is_activesync(desc))) {
 110 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
 111                         continue;
 112 #else
 113                         best = c;
 114 #endif
 115                 }
 116
 117                 /* From the remaining configs, choose the first one whose
 118                  * first interface is for a non-vendor-specific class.
 119                  * Reason: Linux is more likely to have a class driver
 120                  * than a vendor-specific driver. */
 121                 else if (udev->descriptor.bDeviceClass !=
 122                                                 USB_CLASS_VENDOR_SPEC &&
 123                                 (!desc || desc->bInterfaceClass !=
 124                                                 USB_CLASS_VENDOR_SPEC)) {
 125                         best = c;
 126                         break;
 127                 }
 128
 129                 /* If all the remaining configs are vendor-specific,
 130                  * choose the first one. */
 131                 else if (!best)
 132                         best = c;
 133         }
 134
 135         if (insufficient_power > 0)
 136                 dev_info(&udev->dev, "rejected %d configuration%s "
 137                         "due to insufficient available bus power\n",
 138                         insufficient_power, plural(insufficient_power));
 139
 140         if (best) {
 141                 i = best->desc.bConfigurationValue;
 142                 dev_info(&udev->dev,
 143                         "configuration #%d chosen from %d choice%s\n",
 144                         i, num_configs, plural(num_configs));
 145         } else {
 146                 i = -1;
 147                 dev_warn(&udev->dev,
 148                         "no configuration chosen from %d choice%s\n",
 149                         num_configs, plural(num_configs));
 150         }
 151         return i;
 152 }
 153
 154 static int generic_probe(struct usb_device *udev)
 155 {
 156         int err, c;
 157
 158         /* put device-specific files into sysfs */
 159         usb_create_sysfs_dev_files(udev);
 160
 161         /* Choose and set the configuration.  This registers the interfaces
 162          * with the driver core and lets interface drivers bind to them.
 163          */
 164         c = choose_configuration(udev);
 165         if (c >= 0) {
 166                 err = usb_set_configuration(udev, c);
 167                 if (err) {
 168                         dev_err(&udev->dev, "can't set config #%d, error %d\n",
 169                                         c, err);
 170                         /* This need not be fatal.  The user can try to
 171                          * set other configurations. */
 172                 }
 173         }
 174
 175         /* USB device state == configured ... usable */
 176         usb_notify_add_device(udev);
 177
 178         return 0;
 179 }
 180
 181 static void generic_disconnect(struct usb_device *udev)
 182 {
 183         usb_notify_remove_device(udev);
 184
 185         /* if this is only an unbind, not a physical disconnect, then
 186          * unconfigure the device */
 187         if (udev->actconfig)
 188                 usb_set_configuration(udev, -1);
 189
 190         usb_remove_sysfs_dev_files(udev);
 191 }
 192
 193 #ifdef  CONFIG_PM
 194
 195 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 196 {
 197         int rc;
 198
 199         /* Normal USB devices suspend through their upstream port.
 200          * Root hubs don't have upstream ports to suspend,
 201          * so we have to shut down their downstream HC-to-USB
 202          * interfaces manually by doing a bus (or "global") suspend.
 203          */
 204         if (!udev->parent)
 205                 rc = hcd_bus_suspend(udev);
 206         else
 207                 rc = usb_port_suspend(udev);
 208         return rc;
 209 }
 210
 211 static int generic_resume(struct usb_device *udev)
 212 {
 213         int rc;
 214
 215         /* Normal USB devices resume/reset through their upstream port.
 216          * Root hubs don't have upstream ports to resume or reset,
 217          * so we have to start up their downstream HC-to-USB
 218          * interfaces manually by doing a bus (or "global") resume.
 219          */
 220         if (!udev->parent)
 221                 rc = hcd_bus_resume(udev);
 222         else
 223                 rc = usb_port_resume(udev);
 224         return rc;
 225 }
 226
 227 #endif  /* CONFIG_PM */
 228
 229 struct usb_device_driver usb_generic_driver = {
 230         .name = "usb",
 231         .probe = generic_probe,
 232         .disconnect = generic_disconnect,
 233 #ifdef  CONFIG_PM
 234         .suspend = generic_suspend,
 235         .resume = generic_resume,
 236 #endif
 237         .supports_autosuspend = 1,
 238 };