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 choose_configuration(struct usb_device *udev)
  29 {
  30         int i;
  31         int num_configs;
  32         int insufficient_power = 0;
  33         struct usb_host_config *c, *best;
  34
  35         best = NULL;
  36         c = udev->config;
  37         num_configs = udev->descriptor.bNumConfigurations;
  38         for (i = 0; i < num_configs; (i++, c++)) {
  39                 struct usb_interface_descriptor *desc = NULL;
  40
  41                 /* It's possible that a config has no interfaces! */
  42                 if (c->desc.bNumInterfaces > 0)
  43                         desc = &c->intf_cache[0]->altsetting->desc;
  44
  45                 /*
  46                  * HP's USB bus-powered keyboard has only one configuration
  47                  * and it claims to be self-powered; other devices may have
  48                  * similar errors in their descriptors.  If the next test
  49                  * were allowed to execute, such configurations would always
  50                  * be rejected and the devices would not work as expected.
  51                  * In the meantime, we run the risk of selecting a config
  52                  * that requires external power at a time when that power
  53                  * isn't available.  It seems to be the lesser of two evils.
  54                  *
  55                  * Bugzilla #6448 reports a device that appears to crash
  56                  * when it receives a GET_DEVICE_STATUS request!  We don't
  57                  * have any other way to tell whether a device is self-powered,
  58                  * but since we don't use that information anywhere but here,
  59                  * the call has been removed.
  60                  *
  61                  * Maybe the GET_DEVICE_STATUS call and the test below can
  62                  * be reinstated when device firmwares become more reliable.
  63                  * Don't hold your breath.
  64                  */
  65 #if 0
  66                 /* Rule out self-powered configs for a bus-powered device */
  67                 if (bus_powered && (c->desc.bmAttributes &
  68                                         USB_CONFIG_ATT_SELFPOWER))
  69                         continue;
  70 #endif
  71
  72                 /*
  73                  * The next test may not be as effective as it should be.
  74                  * Some hubs have errors in their descriptor, claiming
  75                  * to be self-powered when they are really bus-powered.
  76                  * We will overestimate the amount of current such hubs
  77                  * make available for each port.
  78                  *
  79                  * This is a fairly benign sort of failure.  It won't
  80                  * cause us to reject configurations that we should have
  81                  * accepted.
  82                  */
  83
  84                 /* Rule out configs that draw too much bus current */
  85                 if (c->desc.bMaxPower * 2 > udev->bus_mA) {
  86                         insufficient_power++;
  87                         continue;
  88                 }
  89
  90                 /* If the first config's first interface is COMM/2/0xff
  91                  * (MSFT RNDIS), rule it out unless Linux has host-side
  92                  * RNDIS support. */
  93                 if (i == 0 && desc
  94                                 && desc->bInterfaceClass == USB_CLASS_COMM
  95                                 && desc->bInterfaceSubClass == 2
  96                                 && desc->bInterfaceProtocol == 0xff) {
  97 #ifndef CONFIG_USB_NET_RNDIS_HOST
  98                         continue;
  99 #else
 100                         best = c;
 101 #endif
 102                 }
 103
 104                 /* From the remaining configs, choose the first one whose
 105                  * first interface is for a non-vendor-specific class.
 106                  * Reason: Linux is more likely to have a class driver
 107                  * than a vendor-specific driver. */
 108                 else if (udev->descriptor.bDeviceClass !=
 109                                                 USB_CLASS_VENDOR_SPEC &&
 110                                 (!desc || desc->bInterfaceClass !=
 111                                                 USB_CLASS_VENDOR_SPEC)) {
 112                         best = c;
 113                         break;
 114                 }
 115
 116                 /* If all the remaining configs are vendor-specific,
 117                  * choose the first one. */
 118                 else if (!best)
 119                         best = c;
 120         }
 121
 122         if (insufficient_power > 0)
 123                 dev_info(&udev->dev, "rejected %d configuration%s "
 124                         "due to insufficient available bus power\n",
 125                         insufficient_power, plural(insufficient_power));
 126
 127         if (best) {
 128                 i = best->desc.bConfigurationValue;
 129                 dev_info(&udev->dev,
 130                         "configuration #%d chosen from %d choice%s\n",
 131                         i, num_configs, plural(num_configs));
 132         } else {
 133                 i = -1;
 134                 dev_warn(&udev->dev,
 135                         "no configuration chosen from %d choice%s\n",
 136                         num_configs, plural(num_configs));
 137         }
 138         return i;
 139 }
 140
 141 static int generic_probe(struct usb_device *udev)
 142 {
 143         int err, c;
 144
 145         /* put device-specific files into sysfs */
 146         usb_create_sysfs_dev_files(udev);
 147
 148         /* Choose and set the configuration.  This registers the interfaces
 149          * with the driver core and lets interface drivers bind to them.
 150          */
 151         c = choose_configuration(udev);
 152         if (c >= 0) {
 153                 err = usb_set_configuration(udev, c);
 154                 if (err) {
 155                         dev_err(&udev->dev, "can't set config #%d, error %d\n",
 156                                         c, err);
 157                         /* This need not be fatal.  The user can try to
 158                          * set other configurations. */
 159                 }
 160         }
 161
 162         /* USB device state == configured ... usable */
 163         usb_notify_add_device(udev);
 164
 165         return 0;
 166 }
 167
 168 static void generic_disconnect(struct usb_device *udev)
 169 {
 170         usb_notify_remove_device(udev);
 171
 172         /* if this is only an unbind, not a physical disconnect, then
 173          * unconfigure the device */
 174         if (udev->actconfig)
 175                 usb_set_configuration(udev, 0);
 176
 177         usb_remove_sysfs_dev_files(udev);
 178 }
 179
 180 #ifdef  CONFIG_PM
 181
 182 static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 183 {
 184         /* USB devices enter SUSPEND state through their hubs, but can be
 185          * marked for FREEZE as soon as their children are already idled.
 186          * But those semantics are useless, so we equate the two (sigh).
 187          */
 188         return usb_port_suspend(udev);
 189 }
 190
 191 static int generic_resume(struct usb_device *udev)
 192 {
 193         return usb_port_resume(udev);
 194 }
 195
 196 #endif  /* CONFIG_PM */
 197
 198 struct usb_device_driver usb_generic_driver = {
 199         .name = "usb",
 200         .probe = generic_probe,
 201         .disconnect = generic_disconnect,
 202 #ifdef  CONFIG_PM
 203         .suspend = generic_suspend,
 204         .resume = generic_resume,
 205 #endif
 206         .supports_autosuspend = 1,
 207 };