release/src-rt-6.x.4708/linux/linux-2.6.36/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
  81                 /*
  82                  * The next test may not be as effective as it should be.
  83                  * Some hubs have errors in their descriptor, claiming
  84                  * to be self-powered when they are really bus-powered.
  85                  * We will overestimate the amount of current such hubs
  86                  * make available for each port.
  87                  *
  88                  * This is a fairly benign sort of failure.  It won't
  89                  * cause us to reject configurations that we should have
  90                  * accepted.
  91                  */
  92
  93                 /* Rule out configs that draw too much bus current */
  94                 if (c->desc.bMaxPower * 2 > udev->bus_mA) {
  95                         insufficient_power++;
  96                         continue;
  97                 }
  98
  99                 /* When the first config's first interface is one of Microsoft's
 100                  * pet nonstandard Ethernet-over-USB protocols, ignore it unless
 101                  * this kernel has enabled the necessary host side driver.
 102                  * But: Don't ignore it if it's the only config.
 103                  */
 104                 if (i == 0 && num_configs > 1 && desc &&
 105                                 (is_rndis(desc) || is_activesync(desc))) {
 106 #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
 107                         continue;
 108 #else
 109                         best = c;
 110 #endif
 111                 }
 112
 113                 /* From the remaining configs, choose the first one whose
 114                  * first interface is for a non-vendor-specific class.
 115                  * Reason: Linux is more likely to have a class driver
 116                  * than a vendor-specific driver. */
 117                 else if (udev->descriptor.bDeviceClass !=
 118                                                 USB_CLASS_VENDOR_SPEC &&
 119                                 (desc && desc->bInterfaceClass !=
 120                                                 USB_CLASS_VENDOR_SPEC)) {
 121                         best = c;
 122                         break;
 123                 }
 124
 125                 /* If all the remaining configs are vendor-specific,
 126                  * choose the first one. */
 127                 else if (!best)
 128                         best = c;
 129         }
 130
 131         if (insufficient_power > 0)
 132                 dev_info(&udev->dev, "rejected %d configuration%s "
 133                         "due to insufficient available bus power\n",
 134                         insufficient_power, plural(insufficient_power));
 135
 136         if (best) {
 137                 i = best->desc.bConfigurationValue;
 138                 dev_dbg(&udev->dev,
 139                         "configuration #%d chosen from %d choice%s\n",
 140                         i, num_configs, plural(num_configs));
 141         } else {
 142                 i = -1;
 143                 dev_warn(&udev->dev,
 144                         "no configuration chosen from %d choice%s\n",
 145                         num_configs, plural(num_configs));
 146         }
 147         return i;
 148 }
 149
 150 static int generic_probe(struct usb_device *udev)
 151 {
 152         int err, c;
 153
 154         /* Choose and set the configuration.  This registers the interfaces
 155          * with the driver core and lets interface drivers bind to them.
 156          */
 157         if (usb_device_is_owned(udev))
 158                 ;               /* Don't configure if the device is owned */
 159         else if (udev->authorized == 0)
 160                 dev_err(&udev->dev, "Device is not authorized for usage\n");
 161         else {
 162                 c = usb_choose_configuration(udev);
 163                 if (c >= 0) {
 164                         err = usb_set_configuration(udev, c);
 165                         if (err) {
 166                                 dev_err(&udev->dev, "can't set config #%d, error %d\n",
 167                                         c, err);
 168                                 /* This need not be fatal.  The user can try to
 169                                  * set other configurations. */
 170                         }
 171                 }
 172         }
 173         /* USB device state == configured ... usable */
 174         usb_notify_add_device(udev);
 175
 176         return 0;
 177 }
 178
 179 static void generic_disconnect(struct usb_device *udev)
 180 {
 181         usb_notify_remove_device(udev);
 182
 183         /* if this is only an unbind, not a physical disconnect, then
 184          * unconfigure the device */
 185         if (udev->actconfig)
 186                 usb_set_configuration(udev, -1);
 187 }
 188
 189 #ifdef  CONFIG_PM
 190
 191 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 192 {
 193         int rc;
 194
 195         /* Normal USB devices suspend through their upstream port.
 196          * Root hubs don't have upstream ports to suspend,
 197          * so we have to shut down their downstream HC-to-USB
 198          * interfaces manually by doing a bus (or "global") suspend.
 199          */
 200         if (!udev->parent)
 201                 rc = hcd_bus_suspend(udev, msg);
 202
 203         /* Non-root devices don't need to do anything for FREEZE or PRETHAW */
 204         else if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
 205                 rc = 0;
 206         else
 207                 rc = usb_port_suspend(udev, msg);
 208
 209         return rc;
 210 }
 211
 212 static int generic_resume(struct usb_device *udev, pm_message_t msg)
 213 {
 214         int rc;
 215
 216         /* Normal USB devices resume/reset through their upstream port.
 217          * Root hubs don't have upstream ports to resume or reset,
 218          * so we have to start up their downstream HC-to-USB
 219          * interfaces manually by doing a bus (or "global") resume.
 220          */
 221         if (!udev->parent)
 222                 rc = hcd_bus_resume(udev, msg);
 223         else
 224                 rc = usb_port_resume(udev, msg);
 225         return rc;
 226 }
 227
 228 #endif  /* CONFIG_PM */
 229
 230 struct usb_device_driver usb_generic_driver = {
 231         .name = "usb",
 232         .probe = generic_probe,
 233         .disconnect = generic_disconnect,
 234 #ifdef  CONFIG_PM
 235         .suspend = generic_suspend,
 236         .resume = generic_resume,
 237 #endif
 238         .supports_autosuspend = 1,
 239 };