generic.c

Go to the documentation of this file.

/*
 * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
 *
 * (C) Copyright 2005 Greg Kroah-Hartman <[email protected]>
 *
 * based on drivers/usb/usb.c which had the following copyrights:
 *  (C) Copyright Linus Torvalds 1999
 *  (C) Copyright Johannes Erdfelt 1999-2001
 *  (C) Copyright Andreas Gal 1999
 *  (C) Copyright Gregory P. Smith 1999
 *  (C) Copyright Deti Fliegl 1999 (new USB architecture)
 *  (C) Copyright Randy Dunlap 2000
 *  (C) Copyright David Brownell 2000-2004
 *  (C) Copyright Yggdrasil Computing, Inc. 2000
 *      (usb_device_id matching changes by Adam J. Richter)
 *  (C) Copyright Greg Kroah-Hartman 2002-2003
 *
 */

#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include "usb.h"

static inline const char *plural(int n)
{
    return (n == 1 ? "" : "s");
}

static int is_rndis(struct usb_interface_descriptor *desc)
{
    return desc->bInterfaceClass == USB_CLASS_COMM
        && desc->bInterfaceSubClass == 2
        && desc->bInterfaceProtocol == 0xff;
}

static int is_activesync(struct usb_interface_descriptor *desc)
{
    return desc->bInterfaceClass == USB_CLASS_MISC
        && desc->bInterfaceSubClass == 1
        && desc->bInterfaceProtocol == 1;
}

int usb_choose_configuration(struct usb_device *udev)
{
    int i;
    int num_configs;
    int insufficient_power = 0;
    struct usb_host_config *c, *best;

    best = NULL;
    c = udev->config;
    num_configs = udev->descriptor.bNumConfigurations;
    for (i = 0; i < num_configs; (i++, c++)) {
        struct usb_interface_descriptor *desc = NULL;

        /* It's possible that a config has no interfaces! */
        if (c->desc.bNumInterfaces > 0)
            desc = &c->intf_cache[0]->altsetting->desc;

        /*
         * HP's USB bus-powered keyboard has only one configuration
         * and it claims to be self-powered; other devices may have
         * similar errors in their descriptors.  If the next test
         * were allowed to execute, such configurations would always
         * be rejected and the devices would not work as expected.
         * In the meantime, we run the risk of selecting a config
         * that requires external power at a time when that power
         * isn't available.  It seems to be the lesser of two evils.
         *
         * Bugzilla #6448 reports a device that appears to crash
         * when it receives a GET_DEVICE_STATUS request!  We don't
         * have any other way to tell whether a device is self-powered,
         * but since we don't use that information anywhere but here,
         * the call has been removed.
         *
         * Maybe the GET_DEVICE_STATUS call and the test below can
         * be reinstated when device firmwares become more reliable.
         * Don't hold your breath.
         */
#if 0
        /* Rule out self-powered configs for a bus-powered device */
        if (bus_powered && (c->desc.bmAttributes &
                    USB_CONFIG_ATT_SELFPOWER))
            continue;
#endif

        /*
         * The next test may not be as effective as it should be.
         * Some hubs have errors in their descriptor, claiming
         * to be self-powered when they are really bus-powered.
         * We will overestimate the amount of current such hubs
         * make available for each port.
         *
         * This is a fairly benign sort of failure.  It won't
         * cause us to reject configurations that we should have
         * accepted.
         */

        /* Rule out configs that draw too much bus current */
        if (c->desc.bMaxPower * 2 > udev->bus_mA) {
            insufficient_power++;
            continue;
        }

        /* When the first config's first interface is one of Microsoft's
         * pet nonstandard Ethernet-over-USB protocols, ignore it unless
         * this kernel has enabled the necessary host side driver.
         * But: Don't ignore it if it's the only config.
         */
        if (i == 0 && num_configs > 1 && desc &&
                (is_rndis(desc) || is_activesync(desc))) {
#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
            continue;
#else
            best = c;
#endif
        }

        /* From the remaining configs, choose the first one whose
         * first interface is for a non-vendor-specific class.
         * Reason: Linux is more likely to have a class driver
         * than a vendor-specific driver. */
        else if (udev->descriptor.bDeviceClass !=
                        USB_CLASS_VENDOR_SPEC &&
                (desc && desc->bInterfaceClass !=
                        USB_CLASS_VENDOR_SPEC)) {
            best = c;
            break;
        }

        /* If all the remaining configs are vendor-specific,
         * choose the first one. */
        else if (!best)
            best = c;
    }

    if (insufficient_power > 0)
        dev_info(&udev->dev, "rejected %d configuration%s "
            "due to insufficient available bus power\n",
            insufficient_power, plural(insufficient_power));

    if (best) {
        i = best->desc.bConfigurationValue;
        dev_dbg(&udev->dev,
            "configuration #%d chosen from %d choice%s\n",
            i, num_configs, plural(num_configs));
    } else {
        i = -1;
        dev_warn(&udev->dev,
            "no configuration chosen from %d choice%s\n",
            num_configs, plural(num_configs));
    }
    return i;
}

static int generic_probe(struct usb_device *udev)
{
    int err, c;

    /* Choose and set the configuration.  This registers the interfaces
     * with the driver core and lets interface drivers bind to them.
     */
    if (usb_device_is_owned(udev))
        ;       /* Don't configure if the device is owned */
    else if (udev->authorized == 0)
        dev_err(&udev->dev, "Device is not authorized for usage\n");
    else {
        c = usb_choose_configuration(udev);
        if (c >= 0) {
            err = usb_set_configuration(udev, c);
            if (err) {
                dev_err(&udev->dev, "can't set config #%d, error %d\n",
                    c, err);
                /* This need not be fatal.  The user can try to
                 * set other configurations. */
            }
        }
    }
    /* USB device state == configured ... usable */
    usb_notify_add_device(udev);

    return 0;
}

static void generic_disconnect(struct usb_device *udev)
{
    usb_notify_remove_device(udev);

    /* if this is only an unbind, not a physical disconnect, then
     * unconfigure the device */
    if (udev->actconfig)
        usb_set_configuration(udev, -1);
}

#ifdef  CONFIG_PM

static int generic_suspend(struct usb_device *udev, pm_message_t msg)
{
    int rc;

    /* Normal USB devices suspend through their upstream port.
     * Root hubs don't have upstream ports to suspend,
     * so we have to shut down their downstream HC-to-USB
     * interfaces manually by doing a bus (or "global") suspend.
     */
    if (!udev->parent)
        rc = hcd_bus_suspend(udev, msg);

    /* Non-root devices don't need to do anything for FREEZE or PRETHAW */
    else if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
        rc = 0;
    else
        rc = usb_port_suspend(udev, msg);

    return rc;
}

static int generic_resume(struct usb_device *udev, pm_message_t msg)
{
    int rc;

    /* Normal USB devices resume/reset through their upstream port.
     * Root hubs don't have upstream ports to resume or reset,
     * so we have to start up their downstream HC-to-USB
     * interfaces manually by doing a bus (or "global") resume.
     */
    if (!udev->parent)
        rc = hcd_bus_resume(udev, msg);
    else
        rc = usb_port_resume(udev, msg);
    return rc;
}

#endif  /* CONFIG_PM */

struct usb_device_driver usb_generic_driver = {
    .name = "usb",
    .probe = generic_probe,
    .disconnect = generic_disconnect,
#ifdef  CONFIG_PM
    .suspend = generic_suspend,
    .resume = generic_resume,
#endif
    .supports_autosuspend = 1,
};