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, 0); 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 }; 220