USB: Add autosuspend support to the hub driver

[linux-drm-fsl-dcu.git] / drivers / usb / core / hub.c

/*
 * USB hub driver.
 *
 * (C) Copyright 1999 Linus Torvalds
 * (C) Copyright 1999 Johannes Erdfelt
 * (C) Copyright 1999 Gregory P. Smith
 * (C) Copyright 2001 Brad Hards (bhards@bigpond.net.au)
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/ioctl.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/kthread.h>
#include <linux/mutex.h>

#include <asm/semaphore.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>

#include "usb.h"
#include "hcd.h"
#include "hub.h"

struct usb_hub {
        struct device           *intfdev;       /* the "interface" device */
        struct usb_device       *hdev;
        struct urb              *urb;           /* for interrupt polling pipe */

        /* buffer for urb ... with extra space in case of babble */
        char                    (*buffer)[8];
        dma_addr_t              buffer_dma;     /* DMA address for buffer */
        union {
                struct usb_hub_status   hub;
                struct usb_port_status  port;
        }                       *status;        /* buffer for status reports */

        int                     error;          /* last reported error */
        int                     nerrors;        /* track consecutive errors */

        struct list_head        event_list;     /* hubs w/data or errs ready */
        unsigned long           event_bits[1];  /* status change bitmask */
        unsigned long           change_bits[1]; /* ports with logical connect
                                                        status change */
        unsigned long           busy_bits[1];   /* ports being reset or
                                                        resumed */
#if USB_MAXCHILDREN > 31 /* 8*sizeof(unsigned long) - 1 */
#error event_bits[] is too short!
#endif

        struct usb_hub_descriptor *descriptor;  /* class descriptor */
        struct usb_tt           tt;             /* Transaction Translator */

        unsigned                mA_per_port;    /* current for each child */

        unsigned                limited_power:1;
        unsigned                quiescing:1;
        unsigned                activating:1;

        unsigned                has_indicators:1;
        u8                      indicator[USB_MAXCHILDREN];
        struct work_struct      leds;
};


/* Protect struct usb_device->state and ->children members
 * Note: Both are also protected by ->dev.sem, except that ->state can
 * change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
static DEFINE_SPINLOCK(device_state_lock);

/* khubd's worklist and its lock */
static DEFINE_SPINLOCK(hub_event_lock);
static LIST_HEAD(hub_event_list);       /* List of hubs needing servicing */

/* Wakes up khubd */
static DECLARE_WAIT_QUEUE_HEAD(khubd_wait);

static struct task_struct *khubd_task;

/* multithreaded probe logic */
static int multithread_probe =
#ifdef CONFIG_USB_MULTITHREAD_PROBE
        1;
#else
        0;
#endif
module_param(multithread_probe, bool, S_IRUGO);
MODULE_PARM_DESC(multithread_probe, "Run each USB device probe in a new thread");

/* cycle leds on hubs that aren't blinking for attention */
static int blinkenlights = 0;
module_param (blinkenlights, bool, S_IRUGO);
MODULE_PARM_DESC (blinkenlights, "true to cycle leds on hubs");

/*
 * As of 2.6.10 we introduce a new USB device initialization scheme which
 * closely resembles the way Windows works.  Hopefully it will be compatible
 * with a wider range of devices than the old scheme.  However some previously
 * working devices may start giving rise to "device not accepting address"
 * errors; if that happens the user can try the old scheme by adjusting the
 * following module parameters.
 *
 * For maximum flexibility there are two boolean parameters to control the
 * hub driver's behavior.  On the first initialization attempt, if the
 * "old_scheme_first" parameter is set then the old scheme will be used,
 * otherwise the new scheme is used.  If that fails and "use_both_schemes"
 * is set, then the driver will make another attempt, using the other scheme.
 */
static int old_scheme_first = 0;
module_param(old_scheme_first, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(old_scheme_first,
                 "start with the old device initialization scheme");

static int use_both_schemes = 1;
module_param(use_both_schemes, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(use_both_schemes,
                "try the other device initialization scheme if the "
                "first one fails");


#ifdef  DEBUG
static inline char *portspeed (int portstatus)
{
        if (portstatus & (1 << USB_PORT_FEAT_HIGHSPEED))
                return "480 Mb/s";
        else if (portstatus & (1 << USB_PORT_FEAT_LOWSPEED))
                return "1.5 Mb/s";
        else
                return "12 Mb/s";
}
#endif

/* Note that hdev or one of its children must be locked! */
static inline struct usb_hub *hdev_to_hub(struct usb_device *hdev)
{
        return usb_get_intfdata(hdev->actconfig->interface[0]);
}

/* USB 2.0 spec Section 11.24.4.5 */
static int get_hub_descriptor(struct usb_device *hdev, void *data, int size)
{
        int i, ret;

        for (i = 0; i < 3; i++) {
                ret = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_DESCRIPTOR, USB_DIR_IN | USB_RT_HUB,
                        USB_DT_HUB << 8, 0, data, size,
                        USB_CTRL_GET_TIMEOUT);
                if (ret >= (USB_DT_HUB_NONVAR_SIZE + 2))
                        return ret;
        }
        return -EINVAL;
}

/*
 * USB 2.0 spec Section 11.24.2.1
 */
static int clear_hub_feature(struct usb_device *hdev, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_CLEAR_FEATURE, USB_RT_HUB, feature, 0, NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.2
 */
static int clear_port_feature(struct usb_device *hdev, int port1, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_CLEAR_FEATURE, USB_RT_PORT, feature, port1,
                NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.13
 */
static int set_port_feature(struct usb_device *hdev, int port1, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_SET_FEATURE, USB_RT_PORT, feature, port1,
                NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.7.1.10 and table 11-7
 * for info about using port indicators
 */
static void set_port_led(
        struct usb_hub *hub,
        int port1,
        int selector
)
{
        int status = set_port_feature(hub->hdev, (selector << 8) | port1,
                        USB_PORT_FEAT_INDICATOR);
        if (status < 0)
                dev_dbg (hub->intfdev,
                        "port %d indicator %s status %d\n",
                        port1,
                        ({ char *s; switch (selector) {
                        case HUB_LED_AMBER: s = "amber"; break;
                        case HUB_LED_GREEN: s = "green"; break;
                        case HUB_LED_OFF: s = "off"; break;
                        case HUB_LED_AUTO: s = "auto"; break;
                        default: s = "??"; break;
                        }; s; }),
                        status);
}

#define LED_CYCLE_PERIOD        ((2*HZ)/3)

static void led_work (void *__hub)
{
        struct usb_hub          *hub = __hub;
        struct usb_device       *hdev = hub->hdev;
        unsigned                i;
        unsigned                changed = 0;
        int                     cursor = -1;

        if (hdev->state != USB_STATE_CONFIGURED || hub->quiescing)
                return;

        for (i = 0; i < hub->descriptor->bNbrPorts; i++) {
                unsigned        selector, mode;

                /* 30%-50% duty cycle */

                switch (hub->indicator[i]) {
                /* cycle marker */
                case INDICATOR_CYCLE:
                        cursor = i;
                        selector = HUB_LED_AUTO;
                        mode = INDICATOR_AUTO;
                        break;
                /* blinking green = sw attention */
                case INDICATOR_GREEN_BLINK:
                        selector = HUB_LED_GREEN;
                        mode = INDICATOR_GREEN_BLINK_OFF;
                        break;
                case INDICATOR_GREEN_BLINK_OFF:
                        selector = HUB_LED_OFF;
                        mode = INDICATOR_GREEN_BLINK;
                        break;
                /* blinking amber = hw attention */
                case INDICATOR_AMBER_BLINK:
                        selector = HUB_LED_AMBER;
                        mode = INDICATOR_AMBER_BLINK_OFF;
                        break;
                case INDICATOR_AMBER_BLINK_OFF:
                        selector = HUB_LED_OFF;
                        mode = INDICATOR_AMBER_BLINK;
                        break;
                /* blink green/amber = reserved */
                case INDICATOR_ALT_BLINK:
                        selector = HUB_LED_GREEN;
                        mode = INDICATOR_ALT_BLINK_OFF;
                        break;
                case INDICATOR_ALT_BLINK_OFF:
                        selector = HUB_LED_AMBER;
                        mode = INDICATOR_ALT_BLINK;
                        break;
                default:
                        continue;
                }
                if (selector != HUB_LED_AUTO)
                        changed = 1;
                set_port_led(hub, i + 1, selector);
                hub->indicator[i] = mode;
        }
        if (!changed && blinkenlights) {
                cursor++;
                cursor %= hub->descriptor->bNbrPorts;
                set_port_led(hub, cursor + 1, HUB_LED_GREEN);
                hub->indicator[cursor] = INDICATOR_CYCLE;
                changed++;
        }
        if (changed)
                schedule_delayed_work(&hub->leds, LED_CYCLE_PERIOD);
}

/* use a short timeout for hub/port status fetches */
#define USB_STS_TIMEOUT         1000
#define USB_STS_RETRIES         5

/*
 * USB 2.0 spec Section 11.24.2.6
 */
static int get_hub_status(struct usb_device *hdev,
                struct usb_hub_status *data)
{
        int i, status = -ETIMEDOUT;

        for (i = 0; i < USB_STS_RETRIES && status == -ETIMEDOUT; i++) {
                status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_HUB, 0, 0,
                        data, sizeof(*data), USB_STS_TIMEOUT);
        }
        return status;
}

/*
 * USB 2.0 spec Section 11.24.2.7
 */
static int get_port_status(struct usb_device *hdev, int port1,
                struct usb_port_status *data)
{
        int i, status = -ETIMEDOUT;

        for (i = 0; i < USB_STS_RETRIES && status == -ETIMEDOUT; i++) {
                status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_PORT, 0, port1,
                        data, sizeof(*data), USB_STS_TIMEOUT);
        }
        return status;
}

static void kick_khubd(struct usb_hub *hub)
{
        unsigned long   flags;

        /* Suppress autosuspend until khubd runs */
        to_usb_interface(hub->intfdev)->pm_usage_cnt = 1;

        spin_lock_irqsave(&hub_event_lock, flags);
        if (list_empty(&hub->event_list)) {
                list_add_tail(&hub->event_list, &hub_event_list);
                wake_up(&khubd_wait);
        }
        spin_unlock_irqrestore(&hub_event_lock, flags);
}

void usb_kick_khubd(struct usb_device *hdev)
{
        kick_khubd(hdev_to_hub(hdev));
}


/* completion function, fires on port status changes and various faults */
static void hub_irq(struct urb *urb)
{
        struct usb_hub *hub = urb->context;
        int status;
        int i;
        unsigned long bits;

        switch (urb->status) {
        case -ENOENT:           /* synchronous unlink */
        case -ECONNRESET:       /* async unlink */
        case -ESHUTDOWN:        /* hardware going away */
                return;

        default:                /* presumably an error */
                /* Cause a hub reset after 10 consecutive errors */
                dev_dbg (hub->intfdev, "transfer --> %d\n", urb->status);
                if ((++hub->nerrors < 10) || hub->error)
                        goto resubmit;
                hub->error = urb->status;
                /* FALL THROUGH */

        /* let khubd handle things */
        case 0:                 /* we got data:  port status changed */
                bits = 0;
                for (i = 0; i < urb->actual_length; ++i)
                        bits |= ((unsigned long) ((*hub->buffer)[i]))
                                        << (i*8);
                hub->event_bits[0] = bits;
                break;
        }

        hub->nerrors = 0;

        /* Something happened, let khubd figure it out */
        kick_khubd(hub);

resubmit:
        if (hub->quiescing)
                return;

        if ((status = usb_submit_urb (hub->urb, GFP_ATOMIC)) != 0
                        && status != -ENODEV && status != -EPERM)
                dev_err (hub->intfdev, "resubmit --> %d\n", status);
}

/* USB 2.0 spec Section 11.24.2.3 */
static inline int
hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt)
{
        return usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                               HUB_CLEAR_TT_BUFFER, USB_RT_PORT, devinfo,
                               tt, NULL, 0, 1000);
}

/*
 * enumeration blocks khubd for a long time. we use keventd instead, since
 * long blocking there is the exception, not the rule.  accordingly, HCDs
 * talking to TTs must queue control transfers (not just bulk and iso), so
 * both can talk to the same hub concurrently.
 */
static void hub_tt_kevent (void *arg)
{
        struct usb_hub          *hub = arg;
        unsigned long           flags;

        spin_lock_irqsave (&hub->tt.lock, flags);
        while (!list_empty (&hub->tt.clear_list)) {
                struct list_head        *temp;
                struct usb_tt_clear     *clear;
                struct usb_device       *hdev = hub->hdev;
                int                     status;

                temp = hub->tt.clear_list.next;
                clear = list_entry (temp, struct usb_tt_clear, clear_list);
                list_del (&clear->clear_list);

                /* drop lock so HCD can concurrently report other TT errors */
                spin_unlock_irqrestore (&hub->tt.lock, flags);
                status = hub_clear_tt_buffer (hdev, clear->devinfo, clear->tt);
                spin_lock_irqsave (&hub->tt.lock, flags);

                if (status)
                        dev_err (&hdev->dev,
                                "clear tt %d (%04x) error %d\n",
                                clear->tt, clear->devinfo, status);
                kfree(clear);
        }
        spin_unlock_irqrestore (&hub->tt.lock, flags);
}

/**
 * usb_hub_tt_clear_buffer - clear control/bulk TT state in high speed hub
 * @udev: the device whose split transaction failed
 * @pipe: identifies the endpoint of the failed transaction
 *
 * High speed HCDs use this to tell the hub driver that some split control or
 * bulk transaction failed in a way that requires clearing internal state of
 * a transaction translator.  This is normally detected (and reported) from
 * interrupt context.
 *
 * It may not be possible for that hub to handle additional full (or low)
 * speed transactions until that state is fully cleared out.
 */
void usb_hub_tt_clear_buffer (struct usb_device *udev, int pipe)
{
        struct usb_tt           *tt = udev->tt;
        unsigned long           flags;
        struct usb_tt_clear     *clear;

        /* we've got to cope with an arbitrary number of pending TT clears,
         * since each TT has "at least two" buffers that can need it (and
         * there can be many TTs per hub).  even if they're uncommon.
         */
        if ((clear = kmalloc (sizeof *clear, SLAB_ATOMIC)) == NULL) {
                dev_err (&udev->dev, "can't save CLEAR_TT_BUFFER state\n");
                /* FIXME recover somehow ... RESET_TT? */
                return;
        }

        /* info that CLEAR_TT_BUFFER needs */
        clear->tt = tt->multi ? udev->ttport : 1;
        clear->devinfo = usb_pipeendpoint (pipe);
        clear->devinfo |= udev->devnum << 4;
        clear->devinfo |= usb_pipecontrol (pipe)
                        ? (USB_ENDPOINT_XFER_CONTROL << 11)
                        : (USB_ENDPOINT_XFER_BULK << 11);
        if (usb_pipein (pipe))
                clear->devinfo |= 1 << 15;
        
        /* tell keventd to clear state for this TT */
        spin_lock_irqsave (&tt->lock, flags);
        list_add_tail (&clear->clear_list, &tt->clear_list);
        schedule_work (&tt->kevent);
        spin_unlock_irqrestore (&tt->lock, flags);
}

static void hub_power_on(struct usb_hub *hub)
{
        int port1;
        unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2;
        u16 wHubCharacteristics =
                        le16_to_cpu(hub->descriptor->wHubCharacteristics);

        /* Enable power on each port.  Some hubs have reserved values
         * of LPSM (> 2) in their descriptors, even though they are
         * USB 2.0 hubs.  Some hubs do not implement port-power switching
         * but only emulate it.  In all cases, the ports won't work
         * unless we send these messages to the hub.
         */
        if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2)
                dev_dbg(hub->intfdev, "enabling power on all ports\n");
        else
                dev_dbg(hub->intfdev, "trying to enable port power on "
                                "non-switchable hub\n");
        for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
                set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);

        /* Wait at least 100 msec for power to become stable */
        msleep(max(pgood_delay, (unsigned) 100));
}

static void hub_quiesce(struct usb_hub *hub)
{
        /* (nonblocking) khubd and related activity won't re-trigger */
        hub->quiescing = 1;
        hub->activating = 0;

        /* (blocking) stop khubd and related activity */
        usb_kill_urb(hub->urb);
        if (hub->has_indicators)
                cancel_delayed_work(&hub->leds);
        if (hub->has_indicators || hub->tt.hub)
                flush_scheduled_work();
}

static void hub_activate(struct usb_hub *hub)
{
        int     status;

        hub->quiescing = 0;
        hub->activating = 1;

        status = usb_submit_urb(hub->urb, GFP_NOIO);
        if (status < 0)
                dev_err(hub->intfdev, "activate --> %d\n", status);
        if (hub->has_indicators && blinkenlights)
                schedule_delayed_work(&hub->leds, LED_CYCLE_PERIOD);

        /* scan all ports ASAP */
        kick_khubd(hub);
}

static int hub_hub_status(struct usb_hub *hub,
                u16 *status, u16 *change)
{
        int ret;

        ret = get_hub_status(hub->hdev, &hub->status->hub);
        if (ret < 0)
                dev_err (hub->intfdev,
                        "%s failed (err = %d)\n", __FUNCTION__, ret);
        else {
                *status = le16_to_cpu(hub->status->hub.wHubStatus);
                *change = le16_to_cpu(hub->status->hub.wHubChange); 
                ret = 0;
        }
        return ret;
}

static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
{
        struct usb_device *hdev = hub->hdev;
        int ret;

        if (hdev->children[port1-1] && set_state) {
                usb_set_device_state(hdev->children[port1-1],
                                USB_STATE_NOTATTACHED);
        }
        ret = clear_port_feature(hdev, port1, USB_PORT_FEAT_ENABLE);
        if (ret)
                dev_err(hub->intfdev, "cannot disable port %d (err = %d)\n",
                        port1, ret);

        return ret;
}


/* caller has locked the hub device */
static void hub_pre_reset(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);
        struct usb_device *hdev = hub->hdev;
        int port1;

        for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
                if (hdev->children[port1 - 1]) {
                        usb_disconnect(&hdev->children[port1 - 1]);
                        if (hub->error == 0)
                                hub_port_disable(hub, port1, 0);
                }
        }
        hub_quiesce(hub);
}

/* caller has locked the hub device */
static void hub_post_reset(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);

        hub_activate(hub);
        hub_power_on(hub);
}


static int hub_configure(struct usb_hub *hub,
        struct usb_endpoint_descriptor *endpoint)
{
        struct usb_device *hdev = hub->hdev;
        struct device *hub_dev = hub->intfdev;
        u16 hubstatus, hubchange;
        u16 wHubCharacteristics;
        unsigned int pipe;
        int maxp, ret;
        char *message;

        hub->buffer = usb_buffer_alloc(hdev, sizeof(*hub->buffer), GFP_KERNEL,
                        &hub->buffer_dma);
        if (!hub->buffer) {
                message = "can't allocate hub irq buffer";
                ret = -ENOMEM;
                goto fail;
        }

        hub->status = kmalloc(sizeof(*hub->status), GFP_KERNEL);
        if (!hub->status) {
                message = "can't kmalloc hub status buffer";
                ret = -ENOMEM;
                goto fail;
        }

        hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
        if (!hub->descriptor) {
                message = "can't kmalloc hub descriptor";
                ret = -ENOMEM;
                goto fail;
        }

        /* Request the entire hub descriptor.
         * hub->descriptor can handle USB_MAXCHILDREN ports,
         * but the hub can/will return fewer bytes here.
         */
        ret = get_hub_descriptor(hdev, hub->descriptor,
                        sizeof(*hub->descriptor));
        if (ret < 0) {
                message = "can't read hub descriptor";
                goto fail;
        } else if (hub->descriptor->bNbrPorts > USB_MAXCHILDREN) {
                message = "hub has too many ports!";
                ret = -ENODEV;
                goto fail;
        }

        hdev->maxchild = hub->descriptor->bNbrPorts;
        dev_info (hub_dev, "%d port%s detected\n", hdev->maxchild,
                (hdev->maxchild == 1) ? "" : "s");

        wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);

        if (wHubCharacteristics & HUB_CHAR_COMPOUND) {
                int     i;
                char    portstr [USB_MAXCHILDREN + 1];

                for (i = 0; i < hdev->maxchild; i++)
                        portstr[i] = hub->descriptor->DeviceRemovable
                                    [((i + 1) / 8)] & (1 << ((i + 1) % 8))
                                ? 'F' : 'R';
                portstr[hdev->maxchild] = 0;
                dev_dbg(hub_dev, "compound device; port removable status: %s\n", portstr);
        } else
                dev_dbg(hub_dev, "standalone hub\n");

        switch (wHubCharacteristics & HUB_CHAR_LPSM) {
                case 0x00:
                        dev_dbg(hub_dev, "ganged power switching\n");
                        break;
                case 0x01:
                        dev_dbg(hub_dev, "individual port power switching\n");
                        break;
                case 0x02:
                case 0x03:
                        dev_dbg(hub_dev, "no power switching (usb 1.0)\n");
                        break;
        }

        switch (wHubCharacteristics & HUB_CHAR_OCPM) {
                case 0x00:
                        dev_dbg(hub_dev, "global over-current protection\n");
                        break;
                case 0x08:
                        dev_dbg(hub_dev, "individual port over-current protection\n");
                        break;
                case 0x10:
                case 0x18:
                        dev_dbg(hub_dev, "no over-current protection\n");
                        break;
        }

        spin_lock_init (&hub->tt.lock);
        INIT_LIST_HEAD (&hub->tt.clear_list);
        INIT_WORK (&hub->tt.kevent, hub_tt_kevent, hub);
        switch (hdev->descriptor.bDeviceProtocol) {
                case 0:
                        break;
                case 1:
                        dev_dbg(hub_dev, "Single TT\n");
                        hub->tt.hub = hdev;
                        break;
                case 2:
                        ret = usb_set_interface(hdev, 0, 1);
                        if (ret == 0) {
                                dev_dbg(hub_dev, "TT per port\n");
                                hub->tt.multi = 1;
                        } else
                                dev_err(hub_dev, "Using single TT (err %d)\n",
                                        ret);
                        hub->tt.hub = hdev;
                        break;
                default:
                        dev_dbg(hub_dev, "Unrecognized hub protocol %d\n",
                                hdev->descriptor.bDeviceProtocol);
                        break;
        }

        /* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */
        switch (wHubCharacteristics & HUB_CHAR_TTTT) {
                case HUB_TTTT_8_BITS:
                        if (hdev->descriptor.bDeviceProtocol != 0) {
                                hub->tt.think_time = 666;
                                dev_dbg(hub_dev, "TT requires at most %d "
                                                "FS bit times (%d ns)\n",
                                        8, hub->tt.think_time);
                        }
                        break;
                case HUB_TTTT_16_BITS:
                        hub->tt.think_time = 666 * 2;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                        "FS bit times (%d ns)\n",
                                16, hub->tt.think_time);
                        break;
                case HUB_TTTT_24_BITS:
                        hub->tt.think_time = 666 * 3;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                        "FS bit times (%d ns)\n",
                                24, hub->tt.think_time);
                        break;
                case HUB_TTTT_32_BITS:
                        hub->tt.think_time = 666 * 4;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                        "FS bit times (%d ns)\n",
                                32, hub->tt.think_time);
                        break;
        }

        /* probe() zeroes hub->indicator[] */
        if (wHubCharacteristics & HUB_CHAR_PORTIND) {
                hub->has_indicators = 1;
                dev_dbg(hub_dev, "Port indicators are supported\n");
        }

        dev_dbg(hub_dev, "power on to power good time: %dms\n",
                hub->descriptor->bPwrOn2PwrGood * 2);

        /* power budgeting mostly matters with bus-powered hubs,
         * and battery-powered root hubs (may provide just 8 mA).
         */
        ret = usb_get_status(hdev, USB_RECIP_DEVICE, 0, &hubstatus);
        if (ret < 2) {
                message = "can't get hub status";
                goto fail;
        }
        le16_to_cpus(&hubstatus);
        if (hdev == hdev->bus->root_hub) {
                if (hdev->bus_mA == 0 || hdev->bus_mA >= 500)
                        hub->mA_per_port = 500;
                else {
                        hub->mA_per_port = hdev->bus_mA;
                        hub->limited_power = 1;
                }
        } else if ((hubstatus & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                dev_dbg(hub_dev, "hub controller current requirement: %dmA\n",
                        hub->descriptor->bHubContrCurrent);
                hub->limited_power = 1;
                if (hdev->maxchild > 0) {
                        int remaining = hdev->bus_mA -
                                        hub->descriptor->bHubContrCurrent;

                        if (remaining < hdev->maxchild * 100)
                                dev_warn(hub_dev,
                                        "insufficient power available "
                                        "to use all downstream ports\n");
                        hub->mA_per_port = 100;         /* 7.2.1.1 */
                }
        } else {        /* Self-powered external hub */
                /* FIXME: What about battery-powered external hubs that
                 * provide less current per port? */
                hub->mA_per_port = 500;
        }
        if (hub->mA_per_port < 500)
                dev_dbg(hub_dev, "%umA bus power budget for each child\n",
                                hub->mA_per_port);

        ret = hub_hub_status(hub, &hubstatus, &hubchange);
        if (ret < 0) {
                message = "can't get hub status";
                goto fail;
        }

        /* local power status reports aren't always correct */
        if (hdev->actconfig->desc.bmAttributes & USB_CONFIG_ATT_SELFPOWER)
                dev_dbg(hub_dev, "local power source is %s\n",
                        (hubstatus & HUB_STATUS_LOCAL_POWER)
                        ? "lost (inactive)" : "good");

        if ((wHubCharacteristics & HUB_CHAR_OCPM) == 0)
                dev_dbg(hub_dev, "%sover-current condition exists\n",
                        (hubstatus & HUB_STATUS_OVERCURRENT) ? "" : "no ");

        /* set up the interrupt endpoint
         * We use the EP's maxpacket size instead of (PORTS+1+7)/8
         * bytes as USB2.0[11.12.3] says because some hubs are known
         * to send more data (and thus cause overflow). For root hubs,
         * maxpktsize is defined in hcd.c's fake endpoint descriptors
         * to be big enough for at least USB_MAXCHILDREN ports. */
        pipe = usb_rcvintpipe(hdev, endpoint->bEndpointAddress);
        maxp = usb_maxpacket(hdev, pipe, usb_pipeout(pipe));

        if (maxp > sizeof(*hub->buffer))
                maxp = sizeof(*hub->buffer);

        hub->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!hub->urb) {
                message = "couldn't allocate interrupt urb";
                ret = -ENOMEM;
                goto fail;
        }

        usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
                hub, endpoint->bInterval);
        hub->urb->transfer_dma = hub->buffer_dma;
        hub->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

        /* maybe cycle the hub leds */
        if (hub->has_indicators && blinkenlights)
                hub->indicator [0] = INDICATOR_CYCLE;

        hub_power_on(hub);
        hub_activate(hub);
        return 0;

fail:
        dev_err (hub_dev, "config failed, %s (err %d)\n",
                        message, ret);
        /* hub_disconnect() frees urb and descriptor */
        return ret;
}

static unsigned highspeed_hubs;

static void hub_disconnect(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata (intf);
        struct usb_device *hdev;

        /* Disconnect all children and quiesce the hub */
        hub->error = 0;
        hub_pre_reset(intf);

        usb_set_intfdata (intf, NULL);
        hdev = hub->hdev;

        if (hdev->speed == USB_SPEED_HIGH)
                highspeed_hubs--;

        usb_free_urb(hub->urb);
        hub->urb = NULL;

        spin_lock_irq(&hub_event_lock);
        list_del_init(&hub->event_list);
        spin_unlock_irq(&hub_event_lock);

        kfree(hub->descriptor);
        hub->descriptor = NULL;

        kfree(hub->status);
        hub->status = NULL;

        if (hub->buffer) {
                usb_buffer_free(hdev, sizeof(*hub->buffer), hub->buffer,
                                hub->buffer_dma);
                hub->buffer = NULL;
        }

        kfree(hub);
}

static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
        struct usb_host_interface *desc;
        struct usb_endpoint_descriptor *endpoint;
        struct usb_device *hdev;
        struct usb_hub *hub;

        desc = intf->cur_altsetting;
        hdev = interface_to_usbdev(intf);

#ifdef  CONFIG_USB_OTG_BLACKLIST_HUB
        if (hdev->parent) {
                dev_warn(&intf->dev, "ignoring external hub\n");
                return -ENODEV;
        }
#endif

        /* Some hubs have a subclass of 1, which AFAICT according to the */
        /*  specs is not defined, but it works */
        if ((desc->desc.bInterfaceSubClass != 0) &&
            (desc->desc.bInterfaceSubClass != 1)) {
descriptor_error:
                dev_err (&intf->dev, "bad descriptor, ignoring hub\n");
                return -EIO;
        }

        /* Multiple endpoints? What kind of mutant ninja-hub is this? */
        if (desc->desc.bNumEndpoints != 1)
                goto descriptor_error;

        endpoint = &desc->endpoint[0].desc;

        /* If it's not an interrupt in endpoint, we'd better punt! */
        if (!usb_endpoint_is_int_in(endpoint))
                goto descriptor_error;

        /* We found a hub */
        dev_info (&intf->dev, "USB hub found\n");

        hub = kzalloc(sizeof(*hub), GFP_KERNEL);
        if (!hub) {
                dev_dbg (&intf->dev, "couldn't kmalloc hub struct\n");
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&hub->event_list);
        hub->intfdev = &intf->dev;
        hub->hdev = hdev;
        INIT_WORK(&hub->leds, led_work, hub);

        usb_set_intfdata (intf, hub);
        intf->needs_remote_wakeup = 1;

        if (hdev->speed == USB_SPEED_HIGH)
                highspeed_hubs++;

        if (hub_configure(hub, endpoint) >= 0)
                return 0;

        hub_disconnect (intf);
        return -ENODEV;
}

static int
hub_ioctl(struct usb_interface *intf, unsigned int code, void *user_data)
{
        struct usb_device *hdev = interface_to_usbdev (intf);

        /* assert ifno == 0 (part of hub spec) */
        switch (code) {
        case USBDEVFS_HUB_PORTINFO: {
                struct usbdevfs_hub_portinfo *info = user_data;
                int i;

                spin_lock_irq(&device_state_lock);
                if (hdev->devnum <= 0)
                        info->nports = 0;
                else {
                        info->nports = hdev->maxchild;
                        for (i = 0; i < info->nports; i++) {
                                if (hdev->children[i] == NULL)
                                        info->port[i] = 0;
                                else
                                        info->port[i] =
                                                hdev->children[i]->devnum;
                        }
                }
                spin_unlock_irq(&device_state_lock);

                return info->nports + 1;
                }

        default:
                return -ENOSYS;
        }
}


/* grab device/port lock, returning index of that port (zero based).
 * protects the upstream link used by this device from concurrent
 * tree operations like suspend, resume, reset, and disconnect, which
 * apply to everything downstream of a given port.
 */
static int locktree(struct usb_device *udev)
{
        int                     t;
        struct usb_device       *hdev;

        if (!udev)
                return -ENODEV;

        /* root hub is always the first lock in the series */
        hdev = udev->parent;
        if (!hdev) {
                usb_lock_device(udev);
                return 0;
        }

        /* on the path from root to us, lock everything from
         * top down, dropping parent locks when not needed
         */
        t = locktree(hdev);
        if (t < 0)
                return t;

        /* everything is fail-fast once disconnect
         * processing starts
         */
        if (udev->state == USB_STATE_NOTATTACHED) {
                usb_unlock_device(hdev);
                return -ENODEV;
        }

        /* when everyone grabs locks top->bottom,
         * non-overlapping work may be concurrent
         */
        usb_lock_device(udev);
        usb_unlock_device(hdev);
        return udev->portnum;
}

static void recursively_mark_NOTATTACHED(struct usb_device *udev)
{
        int i;

        for (i = 0; i < udev->maxchild; ++i) {
                if (udev->children[i])
                        recursively_mark_NOTATTACHED(udev->children[i]);
        }
        udev->state = USB_STATE_NOTATTACHED;
}

/**
 * usb_set_device_state - change a device's current state (usbcore, hcds)
 * @udev: pointer to device whose state should be changed
 * @new_state: new state value to be stored
 *
 * udev->state is _not_ fully protected by the device lock.  Although
 * most transitions are made only while holding the lock, the state can
 * can change to USB_STATE_NOTATTACHED at almost any time.  This
 * is so that devices can be marked as disconnected as soon as possible,
 * without having to wait for any semaphores to be released.  As a result,
 * all changes to any device's state must be protected by the
 * device_state_lock spinlock.
 *
 * Once a device has been added to the device tree, all changes to its state
 * should be made using this routine.  The state should _not_ be set directly.
 *
 * If udev->state is already USB_STATE_NOTATTACHED then no change is made.
 * Otherwise udev->state is set to new_state, and if new_state is
 * USB_STATE_NOTATTACHED then all of udev's descendants' states are also set
 * to USB_STATE_NOTATTACHED.
 */
void usb_set_device_state(struct usb_device *udev,
                enum usb_device_state new_state)
{
        unsigned long flags;

        spin_lock_irqsave(&device_state_lock, flags);
        if (udev->state == USB_STATE_NOTATTACHED)
                ;       /* do nothing */
        else if (new_state != USB_STATE_NOTATTACHED) {

                /* root hub wakeup capabilities are managed out-of-band
                 * and may involve silicon errata ... ignore them here.
                 */
                if (udev->parent) {
                        if (udev->state == USB_STATE_SUSPENDED
                                        || new_state == USB_STATE_SUSPENDED)
                                ;       /* No change to wakeup settings */
                        else if (new_state == USB_STATE_CONFIGURED)
                                device_init_wakeup(&udev->dev,
                                        (udev->actconfig->desc.bmAttributes
                                         & USB_CONFIG_ATT_WAKEUP));
                        else
                                device_init_wakeup(&udev->dev, 0);
                }
                udev->state = new_state;
        } else
                recursively_mark_NOTATTACHED(udev);
        spin_unlock_irqrestore(&device_state_lock, flags);
}


#ifdef  CONFIG_PM

/**
 * usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
 * @rhdev: struct usb_device for the root hub
 *
 * The USB host controller driver calls this function when its root hub
 * is resumed and Vbus power has been interrupted or the controller
 * has been reset.  The routine marks all the children of the root hub
 * as NOTATTACHED and marks logical connect-change events on their ports.
 */
void usb_root_hub_lost_power(struct usb_device *rhdev)
{
        struct usb_hub *hub;
        int port1;
        unsigned long flags;

        dev_warn(&rhdev->dev, "root hub lost power or was reset\n");

        /* Make sure no potential wakeup events get lost,
         * by forcing the root hub to be resumed.
         */
        rhdev->dev.power.prev_state.event = PM_EVENT_ON;

        spin_lock_irqsave(&device_state_lock, flags);
        hub = hdev_to_hub(rhdev);
        for (port1 = 1; port1 <= rhdev->maxchild; ++port1) {
                if (rhdev->children[port1 - 1]) {
                        recursively_mark_NOTATTACHED(
                                        rhdev->children[port1 - 1]);
                        set_bit(port1, hub->change_bits);
                }
        }
        spin_unlock_irqrestore(&device_state_lock, flags);
}
EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);

#endif  /* CONFIG_PM */

static void choose_address(struct usb_device *udev)
{
        int             devnum;
        struct usb_bus  *bus = udev->bus;

        /* If khubd ever becomes multithreaded, this will need a lock */

        /* Try to allocate the next devnum beginning at bus->devnum_next. */
        devnum = find_next_zero_bit(bus->devmap.devicemap, 128,
                        bus->devnum_next);
        if (devnum >= 128)
                devnum = find_next_zero_bit(bus->devmap.devicemap, 128, 1);

        bus->devnum_next = ( devnum >= 127 ? 1 : devnum + 1);

        if (devnum < 128) {
                set_bit(devnum, bus->devmap.devicemap);
                udev->devnum = devnum;
        }
}

static void release_address(struct usb_device *udev)
{
        if (udev->devnum > 0) {
                clear_bit(udev->devnum, udev->bus->devmap.devicemap);
                udev->devnum = -1;
        }
}

/**
 * usb_disconnect - disconnect a device (usbcore-internal)
 * @pdev: pointer to device being disconnected
 * Context: !in_interrupt ()
 *
 * Something got disconnected. Get rid of it and all of its children.
 *
 * If *pdev is a normal device then the parent hub must already be locked.
 * If *pdev is a root hub then this routine will acquire the
 * usb_bus_list_lock on behalf of the caller.
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 */
void usb_disconnect(struct usb_device **pdev)
{
        struct usb_device       *udev = *pdev;
        int                     i;

        if (!udev) {
                pr_debug ("%s nodev\n", __FUNCTION__);
                return;
        }

        /* mark the device as inactive, so any further urb submissions for
         * this device (and any of its children) will fail immediately.
         * this quiesces everyting except pending urbs.
         */
        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
        dev_info (&udev->dev, "USB disconnect, address %d\n", udev->devnum);

        usb_lock_device(udev);

        /* Free up all the children before we remove this device */
        for (i = 0; i < USB_MAXCHILDREN; i++) {
                if (udev->children[i])
                        usb_disconnect(&udev->children[i]);
        }

        /* deallocate hcd/hardware state ... nuking all pending urbs and
         * cleaning up all state associated with the current configuration
         * so that the hardware is now fully quiesced.
         */
        dev_dbg (&udev->dev, "unregistering device\n");
        usb_disable_device(udev, 0);

        usb_unlock_device(udev);

        /* Unregister the device.  The device driver is responsible
         * for removing the device files from usbfs and sysfs and for
         * de-configuring the device.
         */
        device_del(&udev->dev);

        /* Free the device number and delete the parent's children[]
         * (or root_hub) pointer.
         */
        release_address(udev);

        /* Avoid races with recursively_mark_NOTATTACHED() */
        spin_lock_irq(&device_state_lock);
        *pdev = NULL;
        spin_unlock_irq(&device_state_lock);

        put_device(&udev->dev);
}

#ifdef DEBUG
static void show_string(struct usb_device *udev, char *id, char *string)
{
        if (!string)
                return;
        dev_printk(KERN_INFO, &udev->dev, "%s: %s\n", id, string);
}

#else
static inline void show_string(struct usb_device *udev, char *id, char *string)
{}
#endif


#ifdef  CONFIG_USB_OTG
#include "otg_whitelist.h"
static int __usb_port_suspend(struct usb_device *, int port1);
#endif

static int __usb_new_device(void *void_data)
{
        struct usb_device *udev = void_data;
        int err;

        /* Lock ourself into memory in order to keep a probe sequence
         * sleeping in a new thread from allowing us to be unloaded.
         */
        if (!try_module_get(THIS_MODULE))
                return -EINVAL;

        err = usb_get_configuration(udev);
        if (err < 0) {
                dev_err(&udev->dev, "can't read configurations, error %d\n",
                        err);
                goto fail;
        }

        /* read the standard strings and cache them if present */
        udev->product = usb_cache_string(udev, udev->descriptor.iProduct);
        udev->manufacturer = usb_cache_string(udev,
                        udev->descriptor.iManufacturer);
        udev->serial = usb_cache_string(udev, udev->descriptor.iSerialNumber);

        /* Tell the world! */
        dev_dbg(&udev->dev, "new device strings: Mfr=%d, Product=%d, "
                        "SerialNumber=%d\n",
                        udev->descriptor.iManufacturer,
                        udev->descriptor.iProduct,
                        udev->descriptor.iSerialNumber);
        show_string(udev, "Product", udev->product);
        show_string(udev, "Manufacturer", udev->manufacturer);
        show_string(udev, "SerialNumber", udev->serial);

#ifdef  CONFIG_USB_OTG
        /*
         * OTG-aware devices on OTG-capable root hubs may be able to use SRP,
         * to wake us after we've powered off VBUS; and HNP, switching roles
         * "host" to "peripheral".  The OTG descriptor helps figure this out.
         */
        if (!udev->bus->is_b_host
                        && udev->config
                        && udev->parent == udev->bus->root_hub) {
                struct usb_otg_descriptor       *desc = 0;
                struct usb_bus                  *bus = udev->bus;

                /* descriptor may appear anywhere in config */
                if (__usb_get_extra_descriptor (udev->rawdescriptors[0],
                                        le16_to_cpu(udev->config[0].desc.wTotalLength),
                                        USB_DT_OTG, (void **) &desc) == 0) {
                        if (desc->bmAttributes & USB_OTG_HNP) {
                                unsigned                port1 = udev->portnum;

                                dev_info(&udev->dev,
                                        "Dual-Role OTG device on %sHNP port\n",
                                        (port1 == bus->otg_port)
                                                ? "" : "non-");

                                /* enable HNP before suspend, it's simpler */
                                if (port1 == bus->otg_port)
                                        bus->b_hnp_enable = 1;
                                err = usb_control_msg(udev,
                                        usb_sndctrlpipe(udev, 0),
                                        USB_REQ_SET_FEATURE, 0,
                                        bus->b_hnp_enable
                                                ? USB_DEVICE_B_HNP_ENABLE
                                                : USB_DEVICE_A_ALT_HNP_SUPPORT,
                                        0, NULL, 0, USB_CTRL_SET_TIMEOUT);
                                if (err < 0) {
                                        /* OTG MESSAGE: report errors here,
                                         * customize to match your product.
                                         */
                                        dev_info(&udev->dev,
                                                "can't set HNP mode; %d\n",
                                                err);
                                        bus->b_hnp_enable = 0;
                                }
                        }
                }
        }

        if (!is_targeted(udev)) {

                /* Maybe it can talk to us, though we can't talk to it.
                 * (Includes HNP test device.)
                 */
                if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
                        err = __usb_port_suspend(udev, udev->bus->otg_port);
                        if (err < 0)
                                dev_dbg(&udev->dev, "HNP fail, %d\n", err);
                }
                err = -ENODEV;
                goto fail;
        }
#endif

        /* Register the device.  The device driver is responsible
         * for adding the device files to usbfs and sysfs and for
         * configuring the device.
         */
        err = device_add (&udev->dev);
        if (err) {
                dev_err(&udev->dev, "can't device_add, error %d\n", err);
                goto fail;
        }

exit:
        module_put(THIS_MODULE);
        return err;

fail:
        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
        goto exit;
}

/**
 * usb_new_device - perform initial device setup (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is called with devices which have been enumerated, but not yet
 * configured.  The device descriptor is available, but not descriptors
 * for any device configuration.  The caller must have locked either
 * the parent hub (if udev is a normal device) or else the
 * usb_bus_list_lock (if udev is a root hub).  The parent's pointer to
 * udev has already been installed, but udev is not yet visible through
 * sysfs or other filesystem code.
 *
 * The return value for this function depends on if the
 * multithread_probe variable is set or not.  If it's set, it will
 * return a if the probe thread was successfully created or not.  If the
 * variable is not set, it will return if the device is configured
 * properly or not.  interfaces, in sysfs); else a negative errno value.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Only the hub driver or root-hub registrar should ever call this.
 */
int usb_new_device(struct usb_device *udev)
{
        struct task_struct *probe_task;
        int ret = 0;

        if (multithread_probe) {
                probe_task = kthread_run(__usb_new_device, udev,
                                         "usb-probe-%s", udev->devnum);
                if (IS_ERR(probe_task))
                        ret = PTR_ERR(probe_task);
        } else
                ret = __usb_new_device(udev);

        return ret;
}

static int hub_port_status(struct usb_hub *hub, int port1,
                               u16 *status, u16 *change)
{
        int ret;

        ret = get_port_status(hub->hdev, port1, &hub->status->port);
        if (ret < 0)
                dev_err (hub->intfdev,
                        "%s failed (err = %d)\n", __FUNCTION__, ret);
        else {
                *status = le16_to_cpu(hub->status->port.wPortStatus);
                *change = le16_to_cpu(hub->status->port.wPortChange); 
                ret = 0;
        }
        return ret;
}


/* Returns 1 if @hub is a WUSB root hub, 0 otherwise */
static unsigned hub_is_wusb(struct usb_hub *hub)
{
        struct usb_hcd *hcd;
        if (hub->hdev->parent != NULL)  /* not a root hub? */
                return 0;
        hcd = container_of(hub->hdev->bus, struct usb_hcd, self);
        return hcd->wireless;
}


#define PORT_RESET_TRIES        5
#define SET_ADDRESS_TRIES       2
#define GET_DESCRIPTOR_TRIES    2
#define SET_CONFIG_TRIES        (2 * (use_both_schemes + 1))
#define USE_NEW_SCHEME(i)       ((i) / 2 == old_scheme_first)

#define HUB_ROOT_RESET_TIME     50      /* times are in msec */
#define HUB_SHORT_RESET_TIME    10
#define HUB_LONG_RESET_TIME     200
#define HUB_RESET_TIMEOUT       500

static int hub_port_wait_reset(struct usb_hub *hub, int port1,
                                struct usb_device *udev, unsigned int delay)
{
        int delay_time, ret;
        u16 portstatus;
        u16 portchange;

        for (delay_time = 0;
                        delay_time < HUB_RESET_TIMEOUT;
                        delay_time += delay) {
                /* wait to give the device a chance to reset */
                msleep(delay);

                /* read and decode port status */
                ret = hub_port_status(hub, port1, &portstatus, &portchange);
                if (ret < 0)
                        return ret;

                /* Device went away? */
                if (!(portstatus & USB_PORT_STAT_CONNECTION))
                        return -ENOTCONN;

                /* bomb out completely if something weird happened */
                if ((portchange & USB_PORT_STAT_C_CONNECTION))
                        return -EINVAL;

                /* if we`ve finished resetting, then break out of the loop */
                if (!(portstatus & USB_PORT_STAT_RESET) &&
                    (portstatus & USB_PORT_STAT_ENABLE)) {
                        if (hub_is_wusb(hub))
                                udev->speed = USB_SPEED_VARIABLE;
                        else if (portstatus & USB_PORT_STAT_HIGH_SPEED)
                                udev->speed = USB_SPEED_HIGH;
                        else if (portstatus & USB_PORT_STAT_LOW_SPEED)
                                udev->speed = USB_SPEED_LOW;
                        else
                                udev->speed = USB_SPEED_FULL;
                        return 0;
                }

                /* switch to the long delay after two short delay failures */
                if (delay_time >= 2 * HUB_SHORT_RESET_TIME)
                        delay = HUB_LONG_RESET_TIME;

                dev_dbg (hub->intfdev,
                        "port %d not reset yet, waiting %dms\n",
                        port1, delay);
        }

        return -EBUSY;
}

static int hub_port_reset(struct usb_hub *hub, int port1,
                                struct usb_device *udev, unsigned int delay)
{
        int i, status;

        /* Reset the port */
        for (i = 0; i < PORT_RESET_TRIES; i++) {
                status = set_port_feature(hub->hdev,
                                port1, USB_PORT_FEAT_RESET);
                if (status)
                        dev_err(hub->intfdev,
                                        "cannot reset port %d (err = %d)\n",
                                        port1, status);
                else {
                        status = hub_port_wait_reset(hub, port1, udev, delay);
                        if (status && status != -ENOTCONN)
                                dev_dbg(hub->intfdev,
                                                "port_wait_reset: err = %d\n",
                                                status);
                }

                /* return on disconnect or reset */
                switch (status) {
                case 0:
                        /* TRSTRCY = 10 ms; plus some extra */
                        msleep(10 + 40);
                        /* FALL THROUGH */
                case -ENOTCONN:
                case -ENODEV:
                        clear_port_feature(hub->hdev,
                                port1, USB_PORT_FEAT_C_RESET);
                        /* FIXME need disconnect() for NOTATTACHED device */
                        usb_set_device_state(udev, status
                                        ? USB_STATE_NOTATTACHED
                                        : USB_STATE_DEFAULT);
                        return status;
                }

                dev_dbg (hub->intfdev,
                        "port %d not enabled, trying reset again...\n",
                        port1);
                delay = HUB_LONG_RESET_TIME;
        }

        dev_err (hub->intfdev,
                "Cannot enable port %i.  Maybe the USB cable is bad?\n",
                port1);

        return status;
}

/*
 * Disable a port and mark a logical connnect-change event, so that some
 * time later khubd will disconnect() any existing usb_device on the port
 * and will re-enumerate if there actually is a device attached.
 */
static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
{
        dev_dbg(hub->intfdev, "logical disconnect on port %d\n", port1);
        hub_port_disable(hub, port1, 1);

        /* FIXME let caller ask to power down the port:
         *  - some devices won't enumerate without a VBUS power cycle
         *  - SRP saves power that way
         *  - ... new call, TBD ...
         * That's easy if this hub can switch power per-port, and
         * khubd reactivates the port later (timer, SRP, etc).
         * Powerdown must be optional, because of reset/DFU.
         */

        set_bit(port1, hub->change_bits);
        kick_khubd(hub);
}

#ifdef  CONFIG_PM

#ifdef  CONFIG_USB_SUSPEND

/*
 * Selective port suspend reduces power; most suspended devices draw
 * less than 500 uA.  It's also used in OTG, along with remote wakeup.
 * All devices below the suspended port are also suspended.
 *
 * Devices leave suspend state when the host wakes them up.  Some devices
 * also support "remote wakeup", where the device can activate the USB
 * tree above them to deliver data, such as a keypress or packet.  In
 * some cases, this wakes the USB host.
 */
static int hub_port_suspend(struct usb_hub *hub, int port1,
                struct usb_device *udev)
{
        int     status;

        // dev_dbg(hub->intfdev, "suspend port %d\n", port1);

        /* enable remote wakeup when appropriate; this lets the device
         * wake up the upstream hub (including maybe the root hub).
         *
         * NOTE:  OTG devices may issue remote wakeup (or SRP) even when
         * we don't explicitly enable it here.
         */
        if (udev->do_remote_wakeup) {
                status = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
                                USB_DEVICE_REMOTE_WAKEUP, 0,
                                NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
                if (status)
                        dev_dbg(&udev->dev,
                                "won't remote wakeup, status %d\n",
                                status);
        }

        /* see 7.1.7.6 */
        status = set_port_feature(hub->hdev, port1, USB_PORT_FEAT_SUSPEND);
        if (status) {
                dev_dbg(hub->intfdev,
                        "can't suspend port %d, status %d\n",
                        port1, status);
                /* paranoia:  "should not happen" */
                (void) usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE,
                                USB_DEVICE_REMOTE_WAKEUP, 0,
                                NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
        } else {
                /* device has up to 10 msec to fully suspend */
                dev_dbg(&udev->dev, "usb %ssuspend\n",
                                udev->auto_pm ? "auto-" : "");
                usb_set_device_state(udev, USB_STATE_SUSPENDED);
                msleep(10);
        }
        return status;
}

/*
 * Devices on USB hub ports have only one "suspend" state, corresponding
 * to ACPI D2, "may cause the device to lose some context".
 * State transitions include:
 *
 *   - suspend, resume ... when the VBUS power link stays live
 *   - suspend, disconnect ... VBUS lost
 *
 * Once VBUS drop breaks the circuit, the port it's using has to go through
 * normal re-enumeration procedures, starting with enabling VBUS power.
 * Other than re-initializing the hub (plug/unplug, except for root hubs),
 * Linux (2.6) currently has NO mechanisms to initiate that:  no khubd
 * timer, no SRP, no requests through sysfs.
 *
 * If CONFIG_USB_SUSPEND isn't enabled, devices only really suspend when
 * the root hub for their bus goes into global suspend ... so we don't
 * (falsely) update the device power state to say it suspended.
 */
static int __usb_port_suspend (struct usb_device *udev, int port1)
{
        int     status = 0;

        /* caller owns the udev device lock */
        if (port1 < 0)
                return port1;

        /* we change the device's upstream USB link,
         * but root hubs have no upstream USB link.
         */
        if (udev->parent)
                status = hub_port_suspend(hdev_to_hub(udev->parent), port1,
                                udev);
        else {
                dev_dbg(&udev->dev, "usb %ssuspend\n",
                                udev->auto_pm ? "auto-" : "");
                usb_set_device_state(udev, USB_STATE_SUSPENDED);
        }
        return status;
}

/*
 * usb_port_suspend - suspend a usb device's upstream port
 * @udev: device that's no longer in active use
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * Suspends a USB device that isn't in active use, conserving power.
 * Devices may wake out of a suspend, if anything important happens,
 * using the remote wakeup mechanism.  They may also be taken out of
 * suspend by the host, using usb_port_resume().  It's also routine
 * to disconnect devices while they are suspended.
 *
 * This only affects the USB hardware for a device; its interfaces
 * (and, for hubs, child devices) must already have been suspended.
 *
 * Suspending OTG devices may trigger HNP, if that's been enabled
 * between a pair of dual-role devices.  That will change roles, such
 * as from A-Host to A-Peripheral or from B-Host back to B-Peripheral.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_suspend(struct usb_device *udev)
{
        return __usb_port_suspend(udev, udev->portnum);
}

/*
 * If the USB "suspend" state is in use (rather than "global suspend"),
 * many devices will be individually taken out of suspend state using
 * special" resume" signaling.  These routines kick in shortly after
 * hardware resume signaling is finished, either because of selective
 * resume (by host) or remote wakeup (by device) ... now see what changed
 * in the tree that's rooted at this device.
 */
static int finish_port_resume(struct usb_device *udev)
{
        int     status;
        u16     devstatus;

        /* caller owns the udev device lock */
        dev_dbg(&udev->dev, "finish resume\n");

        /* usb ch9 identifies four variants of SUSPENDED, based on what
         * state the device resumes to.  Linux currently won't see the
         * first two on the host side; they'd be inside hub_port_init()
         * during many timeouts, but khubd can't suspend until later.
         */
        usb_set_device_state(udev, udev->actconfig
                        ? USB_STATE_CONFIGURED
                        : USB_STATE_ADDRESS);

        /* 10.5.4.5 says be sure devices in the tree are still there.
         * For now let's assume the device didn't go crazy on resume,
         * and device drivers will know about any resume quirks.
         */
        status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);
        if (status >= 0)
                status = (status == 2 ? 0 : -ENODEV);

        if (status)
                dev_dbg(&udev->dev,
                        "gone after usb resume? status %d\n",
                        status);
        else if (udev->actconfig) {
                le16_to_cpus(&devstatus);
                if ((devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP))
                                && udev->parent) {
                        status = usb_control_msg(udev,
                                        usb_sndctrlpipe(udev, 0),
                                        USB_REQ_CLEAR_FEATURE,
                                                USB_RECIP_DEVICE,
                                        USB_DEVICE_REMOTE_WAKEUP, 0,
                                        NULL, 0,
                                        USB_CTRL_SET_TIMEOUT);
                        if (status)
                                dev_dbg(&udev->dev, "disable remote "
                                        "wakeup, status %d\n", status);
                }
                status = 0;

        } else if (udev->devnum <= 0) {
                dev_dbg(&udev->dev, "bogus resume!\n");
                status = -EINVAL;
        }
        return status;
}

static int
hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
{
        int     status;

        // dev_dbg(hub->intfdev, "resume port %d\n", port1);

        set_bit(port1, hub->busy_bits);

        /* see 7.1.7.7; affects power usage, but not budgeting */
        status = clear_port_feature(hub->hdev,
                        port1, USB_PORT_FEAT_SUSPEND);
        if (status) {
                dev_dbg(hub->intfdev,
                        "can't resume port %d, status %d\n",
                        port1, status);
        } else {
                u16             devstatus;
                u16             portchange;

                /* drive resume for at least 20 msec */
                if (udev)
                        dev_dbg(&udev->dev, "usb %sresume\n",
                                        udev->auto_pm ? "auto-" : "");
                msleep(25);

#define LIVE_FLAGS      ( USB_PORT_STAT_POWER \
                        | USB_PORT_STAT_ENABLE \
                        | USB_PORT_STAT_CONNECTION)

                /* Virtual root hubs can trigger on GET_PORT_STATUS to
                 * stop resume signaling.  Then finish the resume
                 * sequence.
                 */
                devstatus = portchange = 0;
                status = hub_port_status(hub, port1,
                                &devstatus, &portchange);
                if (status < 0
                                || (devstatus & LIVE_FLAGS) != LIVE_FLAGS
                                || (devstatus & USB_PORT_STAT_SUSPEND) != 0
                                ) {
                        dev_dbg(hub->intfdev,
                                "port %d status %04x.%04x after resume, %d\n",
                                port1, portchange, devstatus, status);
                        if (status >= 0)
                                status = -ENODEV;
                } else {
                        if (portchange & USB_PORT_STAT_C_SUSPEND)
                                clear_port_feature(hub->hdev, port1,
                                                USB_PORT_FEAT_C_SUSPEND);
                        /* TRSMRCY = 10 msec */
                        msleep(10);
                        if (udev)
                                status = finish_port_resume(udev);
                }
        }
        if (status < 0)
                hub_port_logical_disconnect(hub, port1);

        clear_bit(port1, hub->busy_bits);
        if (!hub->hdev->parent && !hub->busy_bits[0])
                usb_enable_root_hub_irq(hub->hdev->bus);

        return status;
}

/*
 * usb_port_resume - re-activate a suspended usb device's upstream port
 * @udev: device to re-activate
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * This will re-activate the suspended device, increasing power usage
 * while letting drivers communicate again with its endpoints.
 * USB resume explicitly guarantees that the power session between
 * the host and the device is the same as it was when the device
 * suspended.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_resume(struct usb_device *udev)
{
        int     status;

        /* we change the device's upstream USB link,
         * but root hubs have no upstream USB link.
         */
        if (udev->parent) {
                // NOTE this fails if parent is also suspended...
                status = hub_port_resume(hdev_to_hub(udev->parent),
                                udev->portnum, udev);
        } else {
                dev_dbg(&udev->dev, "usb %sresume\n",
                                udev->auto_pm ? "auto-" : "");
                status = finish_port_resume(udev);
        }
        if (status < 0)
                dev_dbg(&udev->dev, "can't resume, status %d\n", status);
        return status;
}

static int remote_wakeup(struct usb_device *udev)
{
        int     status = 0;

        /* All this just to avoid sending a port-resume message
         * to the parent hub! */

        usb_lock_device(udev);
        usb_pm_lock(udev);
        if (udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
                /* TRSMRCY = 10 msec */
                msleep(10);
                status = finish_port_resume(udev);
                if (status == 0)
                        udev->dev.power.power_state.event = PM_EVENT_ON;
        }
        usb_pm_unlock(udev);

        if (status == 0)
                usb_autoresume_device(udev, 0);
        usb_unlock_device(udev);
        return status;
}

#else   /* CONFIG_USB_SUSPEND */

/* When CONFIG_USB_SUSPEND isn't set, we never suspend or resume any ports. */

int usb_port_suspend(struct usb_device *udev)
{
        return 0;
}

static inline int
finish_port_resume(struct usb_device *udev)
{
        return 0;
}

static inline int
hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
{
        return 0;
}

int usb_port_resume(struct usb_device *udev)
{
        return 0;
}

static inline int remote_wakeup(struct usb_device *udev)
{
        return 0;
}

#endif

static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
{
        struct usb_hub          *hub = usb_get_intfdata (intf);
        struct usb_device       *hdev = hub->hdev;
        unsigned                port1;

        /* fail if children aren't already suspended */
        for (port1 = 1; port1 <= hdev->maxchild; port1++) {
                struct usb_device       *udev;

                udev = hdev->children [port1-1];
                if (udev && msg.event == PM_EVENT_SUSPEND &&
#ifdef  CONFIG_USB_SUSPEND
                                udev->state != USB_STATE_SUSPENDED
#else
                                udev->dev.power.power_state.event
                                        == PM_EVENT_ON
#endif
                                ) {
                        if (!hdev->auto_pm)
                                dev_dbg(&intf->dev, "port %d nyet suspended\n",
                                                port1);
                        return -EBUSY;
                }
        }

        dev_dbg(&intf->dev, "%s\n", __FUNCTION__);

        /* "global suspend" of the downstream HC-to-USB interface */
        if (!hdev->parent) {
                struct usb_bus  *bus = hdev->bus;
                if (bus) {
                        int     status = hcd_bus_suspend (bus);

                        if (status != 0) {
                                dev_dbg(&hdev->dev, "'global' suspend %d\n",
                                        status);
                                return status;
                        }
                } else
                        return -EOPNOTSUPP;
        }

        /* stop khubd and related activity */
        hub_quiesce(hub);
        return 0;
}

static int hub_resume(struct usb_interface *intf)
{
        struct usb_hub          *hub = usb_get_intfdata (intf);
        struct usb_device       *hdev = hub->hdev;
        int                     status;

        dev_dbg(&intf->dev, "%s\n", __FUNCTION__);

        /* "global resume" of the downstream HC-to-USB interface */
        if (!hdev->parent) {
                struct usb_bus  *bus = hdev->bus;
                if (bus) {
                        status = hcd_bus_resume (bus);
                        if (status) {
                                dev_dbg(&intf->dev, "'global' resume %d\n",
                                        status);
                                return status;
                        }
                } else
                        return -EOPNOTSUPP;
                if (status == 0) {
                        /* TRSMRCY = 10 msec */
                        msleep(10);
                }
        }

        /* tell khubd to look for changes on this hub */
        hub_activate(hub);
        return 0;
}

#else   /* CONFIG_PM */

static inline int remote_wakeup(struct usb_device *udev)
{
        return 0;
}

#define hub_suspend NULL
#define hub_resume NULL
#endif

void usb_resume_root_hub(struct usb_device *hdev)
{
        struct usb_hub *hub = hdev_to_hub(hdev);

        kick_khubd(hub);
}


/* USB 2.0 spec, 7.1.7.3 / fig 7-29:
 *
 * Between connect detection and reset signaling there must be a delay
 * of 100ms at least for debounce and power-settling.  The corresponding
 * timer shall restart whenever the downstream port detects a disconnect.
 * 
 * Apparently there are some bluetooth and irda-dongles and a number of
 * low-speed devices for which this debounce period may last over a second.
 * Not covered by the spec - but easy to deal with.
 *
 * This implementation uses a 1500ms total debounce timeout; if the
 * connection isn't stable by then it returns -ETIMEDOUT.  It checks
 * every 25ms for transient disconnects.  When the port status has been
 * unchanged for 100ms it returns the port status.
 */

#define HUB_DEBOUNCE_TIMEOUT    1500
#define HUB_DEBOUNCE_STEP         25
#define HUB_DEBOUNCE_STABLE      100

static int hub_port_debounce(struct usb_hub *hub, int port1)
{
        int ret;
        int total_time, stable_time = 0;
        u16 portchange, portstatus;
        unsigned connection = 0xffff;

        for (total_time = 0; ; total_time += HUB_DEBOUNCE_STEP) {
                ret = hub_port_status(hub, port1, &portstatus, &portchange);
                if (ret < 0)
                        return ret;

                if (!(portchange & USB_PORT_STAT_C_CONNECTION) &&
                     (portstatus & USB_PORT_STAT_CONNECTION) == connection) {
                        stable_time += HUB_DEBOUNCE_STEP;
                        if (stable_time >= HUB_DEBOUNCE_STABLE)
                                break;
                } else {
                        stable_time = 0;
                        connection = portstatus & USB_PORT_STAT_CONNECTION;
                }

                if (portchange & USB_PORT_STAT_C_CONNECTION) {
                        clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                }

                if (total_time >= HUB_DEBOUNCE_TIMEOUT)
                        break;
                msleep(HUB_DEBOUNCE_STEP);
        }

        dev_dbg (hub->intfdev,
                "debounce: port %d: total %dms stable %dms status 0x%x\n",
                port1, total_time, stable_time, portstatus);

        if (stable_time < HUB_DEBOUNCE_STABLE)
                return -ETIMEDOUT;
        return portstatus;
}

static void ep0_reinit(struct usb_device *udev)
{
        usb_disable_endpoint(udev, 0 + USB_DIR_IN);
        usb_disable_endpoint(udev, 0 + USB_DIR_OUT);
        udev->ep_in[0] = udev->ep_out[0] = &udev->ep0;
}

#define usb_sndaddr0pipe()      (PIPE_CONTROL << 30)
#define usb_rcvaddr0pipe()      ((PIPE_CONTROL << 30) | USB_DIR_IN)

static int hub_set_address(struct usb_device *udev)
{
        int retval;

        if (udev->devnum == 0)
                return -EINVAL;
        if (udev->state == USB_STATE_ADDRESS)
                return 0;
        if (udev->state != USB_STATE_DEFAULT)
                return -EINVAL;
        retval = usb_control_msg(udev, usb_sndaddr0pipe(),
                USB_REQ_SET_ADDRESS, 0, udev->devnum, 0,
                NULL, 0, USB_CTRL_SET_TIMEOUT);
        if (retval == 0) {
                usb_set_device_state(udev, USB_STATE_ADDRESS);
                ep0_reinit(udev);
        }
        return retval;
}

/* Reset device, (re)assign address, get device descriptor.
 * Device connection must be stable, no more debouncing needed.
 * Returns device in USB_STATE_ADDRESS, except on error.
 *
 * If this is called for an already-existing device (as part of
 * usb_reset_device), the caller must own the device lock.  For a
 * newly detected device that is not accessible through any global
 * pointers, it's not necessary to lock the device.
 */
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
                int retry_counter)
{
        static DEFINE_MUTEX(usb_address0_mutex);

        struct usb_device       *hdev = hub->hdev;
        int                     i, j, retval;
        unsigned                delay = HUB_SHORT_RESET_TIME;
        enum usb_device_speed   oldspeed = udev->speed;
        char                    *speed, *type;

        /* root hub ports have a slightly longer reset period
         * (from USB 2.0 spec, section 7.1.7.5)
         */
        if (!hdev->parent) {
                delay = HUB_ROOT_RESET_TIME;
                if (port1 == hdev->bus->otg_port)
                        hdev->bus->b_hnp_enable = 0;
        }

        /* Some low speed devices have problems with the quick delay, so */
        /*  be a bit pessimistic with those devices. RHbug #23670 */
        if (oldspeed == USB_SPEED_LOW)
                delay = HUB_LONG_RESET_TIME;

        mutex_lock(&usb_address0_mutex);

        /* Reset the device; full speed may morph to high speed */
        retval = hub_port_reset(hub, port1, udev, delay);
        if (retval < 0)         /* error or disconnect */
                goto fail;
                                /* success, speed is known */
        retval = -ENODEV;

        if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
                dev_dbg(&udev->dev, "device reset changed speed!\n");
                goto fail;
        }
        oldspeed = udev->speed;
  
        /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
         * it's fixed size except for full speed devices.
         * For Wireless USB devices, ep0 max packet is always 512 (tho
         * reported as 0xff in the device descriptor). WUSB1.0[4.8.1].
         */
        switch (udev->speed) {
        case USB_SPEED_VARIABLE:        /* fixed at 512 */
                udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(512);
                break;
        case USB_SPEED_HIGH:            /* fixed at 64 */
                udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
                break;
        case USB_SPEED_FULL:            /* 8, 16, 32, or 64 */
                /* to determine the ep0 maxpacket size, try to read
                 * the device descriptor to get bMaxPacketSize0 and
                 * then correct our initial guess.
                 */
                udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
                break;
        case USB_SPEED_LOW:             /* fixed at 8 */
                udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(8);
                break;
        default:
                goto fail;
        }
 
        type = "";
        switch (udev->speed) {
        case USB_SPEED_LOW:     speed = "low";  break;
        case USB_SPEED_FULL:    speed = "full"; break;
        case USB_SPEED_HIGH:    speed = "high"; break;
        case USB_SPEED_VARIABLE:
                                speed = "variable";
                                type = "Wireless ";
                                break;
        default:                speed = "?";    break;
        }
        dev_info (&udev->dev,
                  "%s %s speed %sUSB device using %s and address %d\n",
                  (udev->config) ? "reset" : "new", speed, type,
                  udev->bus->controller->driver->name, udev->devnum);

        /* Set up TT records, if needed  */
        if (hdev->tt) {
                udev->tt = hdev->tt;
                udev->ttport = hdev->ttport;
        } else if (udev->speed != USB_SPEED_HIGH
                        && hdev->speed == USB_SPEED_HIGH) {
                udev->tt = &hub->tt;
                udev->ttport = port1;
        }
 
        /* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
         * Because device hardware and firmware is sometimes buggy in
         * this area, and this is how Linux has done it for ages.
         * Change it cautiously.
         *
         * NOTE:  If USE_NEW_SCHEME() is true we will start by issuing
         * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
         * so it may help with some non-standards-compliant devices.
         * Otherwise we start with SET_ADDRESS and then try to read the
         * first 8 bytes of the device descriptor to get the ep0 maxpacket
         * value.
         */
        for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
                if (USE_NEW_SCHEME(retry_counter)) {
                        struct usb_device_descriptor *buf;
                        int r = 0;

#define GET_DESCRIPTOR_BUFSIZE  64
                        buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
                        if (!buf) {
                                retval = -ENOMEM;
                                continue;
                        }

                        /* Use a short timeout the first time through,
                         * so that recalcitrant full-speed devices with
                         * 8- or 16-byte ep0-maxpackets won't slow things
                         * down tremendously by NAKing the unexpectedly
                         * early status stage.  Also, retry on all errors;
                         * some devices are flakey.
                         * 255 is for WUSB devices, we actually need to use 512.
                         * WUSB1.0[4.8.1].
                         */
                        for (j = 0; j < 3; ++j) {
                                buf->bMaxPacketSize0 = 0;
                                r = usb_control_msg(udev, usb_rcvaddr0pipe(),
                                        USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
                                        USB_DT_DEVICE << 8, 0,
                                        buf, GET_DESCRIPTOR_BUFSIZE,
                                        (i ? USB_CTRL_GET_TIMEOUT : 1000));
                                switch (buf->bMaxPacketSize0) {
                                case 8: case 16: case 32: case 64: case 255:
                                        if (buf->bDescriptorType ==
                                                        USB_DT_DEVICE) {
                                                r = 0;
                                                break;
                                        }
                                        /* FALL THROUGH */
                                default:
                                        if (r == 0)
                                                r = -EPROTO;
                                        break;
                                }
                                if (r == 0)
                                        break;
                        }
                        udev->descriptor.bMaxPacketSize0 =
                                        buf->bMaxPacketSize0;
                        kfree(buf);

                        retval = hub_port_reset(hub, port1, udev, delay);
                        if (retval < 0)         /* error or disconnect */
                                goto fail;
                        if (oldspeed != udev->speed) {
                                dev_dbg(&udev->dev,
                                        "device reset changed speed!\n");
                                retval = -ENODEV;
                                goto fail;
                        }
                        if (r) {
                                dev_err(&udev->dev, "device descriptor "
                                                "read/%s, error %d\n",
                                                "64", r);
                                retval = -EMSGSIZE;
                                continue;
                        }
#undef GET_DESCRIPTOR_BUFSIZE
                }

                for (j = 0; j < SET_ADDRESS_TRIES; ++j) {
                        retval = hub_set_address(udev);
                        if (retval >= 0)
                                break;
                        msleep(200);
                }
                if (retval < 0) {
                        dev_err(&udev->dev,
                                "device not accepting address %d, error %d\n",
                                udev->devnum, retval);
                        goto fail;
                }
 
                /* cope with hardware quirkiness:
                 *  - let SET_ADDRESS settle, some device hardware wants it
                 *  - read ep0 maxpacket even for high and low speed,
                 */
                msleep(10);
                if (USE_NEW_SCHEME(retry_counter))
                        break;

                retval = usb_get_device_descriptor(udev, 8);
                if (retval < 8) {
                        dev_err(&udev->dev, "device descriptor "
                                        "read/%s, error %d\n",
                                        "8", retval);
                        if (retval >= 0)
                                retval = -EMSGSIZE;
                } else {
                        retval = 0;
                        break;
                }
        }
        if (retval)
                goto fail;

        i = udev->descriptor.bMaxPacketSize0 == 0xff?
            512 : udev->descriptor.bMaxPacketSize0;
        if (le16_to_cpu(udev->ep0.desc.wMaxPacketSize) != i) {
                if (udev->speed != USB_SPEED_FULL ||
                                !(i == 8 || i == 16 || i == 32 || i == 64)) {
                        dev_err(&udev->dev, "ep0 maxpacket = %d\n", i);
                        retval = -EMSGSIZE;
                        goto fail;
                }
                dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
                ep0_reinit(udev);
        }
  
        retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE);
        if (retval < (signed)sizeof(udev->descriptor)) {
                dev_err(&udev->dev, "device descriptor read/%s, error %d\n",
                        "all", retval);
                if (retval >= 0)
                        retval = -ENOMSG;
                goto fail;
        }

        retval = 0;

fail:
        if (retval)
                hub_port_disable(hub, port1, 0);
        mutex_unlock(&usb_address0_mutex);
        return retval;
}

static void
check_highspeed (struct usb_hub *hub, struct usb_device *udev, int port1)
{
        struct usb_qualifier_descriptor *qual;
        int                             status;

        qual = kmalloc (sizeof *qual, SLAB_KERNEL);
        if (qual == NULL)
                return;

        status = usb_get_descriptor (udev, USB_DT_DEVICE_QUALIFIER, 0,
                        qual, sizeof *qual);
        if (status == sizeof *qual) {
                dev_info(&udev->dev, "not running at top speed; "
                        "connect to a high speed hub\n");
                /* hub LEDs are probably harder to miss than syslog */
                if (hub->has_indicators) {
                        hub->indicator[port1-1] = INDICATOR_GREEN_BLINK;
                        schedule_work (&hub->leds);
                }
        }
        kfree(qual);
}

static unsigned
hub_power_remaining (struct usb_hub *hub)
{
        struct usb_device *hdev = hub->hdev;
        int remaining;
        int port1;

        if (!hub->limited_power)
                return 0;

        remaining = hdev->bus_mA - hub->descriptor->bHubContrCurrent;
        for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
                struct usb_device       *udev = hdev->children[port1 - 1];
                int                     delta;

                if (!udev)
                        continue;

                /* Unconfigured devices may not use more than 100mA,
                 * or 8mA for OTG ports */
                if (udev->actconfig)
                        delta = udev->actconfig->desc.bMaxPower * 2;
                else if (port1 != udev->bus->otg_port || hdev->parent)
                        delta = 100;
                else
                        delta = 8;
                if (delta > hub->mA_per_port)
                        dev_warn(&udev->dev, "%dmA is over %umA budget "
                                        "for port %d!\n",
                                        delta, hub->mA_per_port, port1);
                remaining -= delta;
        }
        if (remaining < 0) {
                dev_warn(hub->intfdev, "%dmA over power budget!\n",
                        - remaining);
                remaining = 0;
        }
        return remaining;
}

/* Handle physical or logical connection change events.
 * This routine is called when:
 *      a port connection-change occurs;
 *      a port enable-change occurs (often caused by EMI);
 *      usb_reset_device() encounters changed descriptors (as from
 *              a firmware download)
 * caller already locked the hub
 */
static void hub_port_connect_change(struct usb_hub *hub, int port1,
                                        u16 portstatus, u16 portchange)
{
        struct usb_device *hdev = hub->hdev;
        struct device *hub_dev = hub->intfdev;
        u16 wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);
        int status, i;
 
        dev_dbg (hub_dev,
                "port %d, status %04x, change %04x, %s\n",
                port1, portstatus, portchange, portspeed (portstatus));

        if (hub->has_indicators) {
                set_port_led(hub, port1, HUB_LED_AUTO);
                hub->indicator[port1-1] = INDICATOR_AUTO;
        }
 
        /* Disconnect any existing devices under this port */
        if (hdev->children[port1-1])
                usb_disconnect(&hdev->children[port1-1]);
        clear_bit(port1, hub->change_bits);

#ifdef  CONFIG_USB_OTG
        /* during HNP, don't repeat the debounce */
        if (hdev->bus->is_b_host)
                portchange &= ~USB_PORT_STAT_C_CONNECTION;
#endif

        if (portchange & USB_PORT_STAT_C_CONNECTION) {
                status = hub_port_debounce(hub, port1);
                if (status < 0) {
                        dev_err (hub_dev,
                                "connect-debounce failed, port %d disabled\n",
                                port1);
                        goto done;
                }
                portstatus = status;
        }

        /* Return now if nothing is connected */
        if (!(portstatus & USB_PORT_STAT_CONNECTION)) {

                /* maybe switch power back on (e.g. root hub was reset) */
                if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2
                                && !(portstatus & (1 << USB_PORT_FEAT_POWER)))
                        set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
 
                if (portstatus & USB_PORT_STAT_ENABLE)
                        goto done;
                return;
        }

#ifdef  CONFIG_USB_SUSPEND
        /* If something is connected, but the port is suspended, wake it up. */
        if (portstatus & USB_PORT_STAT_SUSPEND) {
                status = hub_port_resume(hub, port1, NULL);
                if (status < 0) {
                        dev_dbg(hub_dev,
                                "can't clear suspend on port %d; %d\n",
                                port1, status);
                        goto done;
                }
        }
#endif

        for (i = 0; i < SET_CONFIG_TRIES; i++) {
                struct usb_device *udev;

                /* reallocate for each attempt, since references
                 * to the previous one can escape in various ways
                 */
                udev = usb_alloc_dev(hdev, hdev->bus, port1);
                if (!udev) {
                        dev_err (hub_dev,
                                "couldn't allocate port %d usb_device\n",
                                port1);
                        goto done;
                }

                usb_set_device_state(udev, USB_STATE_POWERED);
                udev->speed = USB_SPEED_UNKNOWN;
                udev->bus_mA = hub->mA_per_port;
                udev->level = hdev->level + 1;

                /* set the address */
                choose_address(udev);
                if (udev->devnum <= 0) {
                        status = -ENOTCONN;     /* Don't retry */
                        goto loop;
                }

                /* reset and get descriptor */
                status = hub_port_init(hub, udev, port1, i);
                if (status < 0)
                        goto loop;

                /* consecutive bus-powered hubs aren't reliable; they can
                 * violate the voltage drop budget.  if the new child has
                 * a "powered" LED, users should notice we didn't enable it
                 * (without reading syslog), even without per-port LEDs
                 * on the parent.
                 */
                if (udev->descriptor.bDeviceClass == USB_CLASS_HUB
                                && udev->bus_mA <= 100) {
                        u16     devstat;

                        status = usb_get_status(udev, USB_RECIP_DEVICE, 0,
                                        &devstat);
                        if (status < 2) {
                                dev_dbg(&udev->dev, "get status %d ?\n", status);
                                goto loop_disable;
                        }
                        le16_to_cpus(&devstat);
                        if ((devstat & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                                dev_err(&udev->dev,
                                        "can't connect bus-powered hub "
                                        "to this port\n");
                                if (hub->has_indicators) {
                                        hub->indicator[port1-1] =
                                                INDICATOR_AMBER_BLINK;
                                        schedule_work (&hub->leds);
                                }
                                status = -ENOTCONN;     /* Don't retry */
                                goto loop_disable;
                        }
                }
 
                /* check for devices running slower than they could */
                if (le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0200
                                && udev->speed == USB_SPEED_FULL
                                && highspeed_hubs != 0)
                        check_highspeed (hub, udev, port1);

                /* Store the parent's children[] pointer.  At this point
                 * udev becomes globally accessible, although presumably
                 * no one will look at it until hdev is unlocked.
                 */
                status = 0;

                /* We mustn't add new devices if the parent hub has
                 * been disconnected; we would race with the
                 * recursively_mark_NOTATTACHED() routine.
                 */
                spin_lock_irq(&device_state_lock);
                if (hdev->state == USB_STATE_NOTATTACHED)
                        status = -ENOTCONN;
                else
                        hdev->children[port1-1] = udev;
                spin_unlock_irq(&device_state_lock);

                /* Run it through the hoops (find a driver, etc) */
                if (!status) {
                        status = usb_new_device(udev);
                        if (status) {
                                spin_lock_irq(&device_state_lock);
                                hdev->children[port1-1] = NULL;
                                spin_unlock_irq(&device_state_lock);
                        }
                }

                if (status)
                        goto loop_disable;

                status = hub_power_remaining(hub);
                if (status)
                        dev_dbg(hub_dev, "%dmA power budget left\n", status);

                return;

loop_disable:
                hub_port_disable(hub, port1, 1);
loop:
                ep0_reinit(udev);
                release_address(udev);
                usb_put_dev(udev);
                if (status == -ENOTCONN)
                        break;
        }
 
done:
        hub_port_disable(hub, port1, 1);
}

static void hub_events(void)
{
        struct list_head *tmp;
        struct usb_device *hdev;
        struct usb_interface *intf;
        struct usb_hub *hub;
        struct device *hub_dev;
        u16 hubstatus;
        u16 hubchange;
        u16 portstatus;
        u16 portchange;
        int i, ret;
        int connect_change;

        /*
         *  We restart the list every time to avoid a deadlock with
         * deleting hubs downstream from this one. This should be
         * safe since we delete the hub from the event list.
         * Not the most efficient, but avoids deadlocks.
         */
        while (1) {

                /* Grab the first entry at the beginning of the list */
                spin_lock_irq(&hub_event_lock);
                if (list_empty(&hub_event_list)) {
                        spin_unlock_irq(&hub_event_lock);
                        break;
                }

                tmp = hub_event_list.next;
                list_del_init(tmp);

                hub = list_entry(tmp, struct usb_hub, event_list);
                hdev = hub->hdev;
                intf = to_usb_interface(hub->intfdev);
                hub_dev = &intf->dev;

                dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
                                hdev->state, hub->descriptor
                                        ? hub->descriptor->bNbrPorts
                                        : 0,
                                /* NOTE: expects max 15 ports... */
                                (u16) hub->change_bits[0],
                                (u16) hub->event_bits[0]);

                usb_get_intf(intf);
                spin_unlock_irq(&hub_event_lock);

                /* Lock the device, then check to see if we were
                 * disconnected while waiting for the lock to succeed. */
                if (locktree(hdev) < 0) {
                        usb_put_intf(intf);
                        continue;
                }
                if (hub != usb_get_intfdata(intf))
                        goto loop;

                /* If the hub has died, clean up after it */
                if (hdev->state == USB_STATE_NOTATTACHED) {
                        hub->error = -ENODEV;
                        hub_pre_reset(intf);
                        goto loop;
                }

                /* Autoresume */
                ret = usb_autopm_get_interface(intf);
                if (ret) {
                        dev_dbg(hub_dev, "Can't autoresume: %d\n", ret);
                        goto loop;
                }

                /* If this is an inactive hub, do nothing */
                if (hub->quiescing)
                        goto loop_autopm;

                if (hub->error) {
                        dev_dbg (hub_dev, "resetting for error %d\n",
                                hub->error);

                        ret = usb_reset_composite_device(hdev, intf);
                        if (ret) {
                                dev_dbg (hub_dev,
                                        "error resetting hub: %d\n", ret);
                                goto loop_autopm;
                        }

                        hub->nerrors = 0;
                        hub->error = 0;
                }

                /* deal with port status changes */
                for (i = 1; i <= hub->descriptor->bNbrPorts; i++) {
                        if (test_bit(i, hub->busy_bits))
                                continue;
                        connect_change = test_bit(i, hub->change_bits);
                        if (!test_and_clear_bit(i, hub->event_bits) &&
                                        !connect_change && !hub->activating)
                                continue;

                        ret = hub_port_status(hub, i,
                                        &portstatus, &portchange);
                        if (ret < 0)
                                continue;

                        if (hub->activating && !hdev->children[i-1] &&
                                        (portstatus &
                                                USB_PORT_STAT_CONNECTION))
                                connect_change = 1;

                        if (portchange & USB_PORT_STAT_C_CONNECTION) {
                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_CONNECTION);
                                connect_change = 1;
                        }

                        if (portchange & USB_PORT_STAT_C_ENABLE) {
                                if (!connect_change)
                                        dev_dbg (hub_dev,
                                                "port %d enable change, "
                                                "status %08x\n",
                                                i, portstatus);
                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_ENABLE);

                                /*
                                 * EM interference sometimes causes badly
                                 * shielded USB devices to be shutdown by
                                 * the hub, this hack enables them again.
                                 * Works at least with mouse driver. 
                                 */
                                if (!(portstatus & USB_PORT_STAT_ENABLE)
                                    && !connect_change
                                    && hdev->children[i-1]) {
                                        dev_err (hub_dev,
                                            "port %i "
                                            "disabled by hub (EMI?), "
                                            "re-enabling...\n",
                                                i);
                                        connect_change = 1;
                                }
                        }

                        if (portchange & USB_PORT_STAT_C_SUSPEND) {
                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_SUSPEND);
                                if (hdev->children[i-1]) {
                                        ret = remote_wakeup(hdev->
                                                        children[i-1]);
                                        if (ret < 0)
                                                connect_change = 1;
                                } else {
                                        ret = -ENODEV;
                                        hub_port_disable(hub, i, 1);
                                }
                                dev_dbg (hub_dev,
                                        "resume on port %d, status %d\n",
                                        i, ret);
                        }
                        
                        if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                                dev_err (hub_dev,
                                        "over-current change on port %d\n",
                                        i);
                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_OVER_CURRENT);
                                hub_power_on(hub);
                        }

                        if (portchange & USB_PORT_STAT_C_RESET) {
                                dev_dbg (hub_dev,
                                        "reset change on port %d\n",
                                        i);
                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_RESET);
                        }

                        if (connect_change)
                                hub_port_connect_change(hub, i,
                                                portstatus, portchange);
                } /* end for i */

                /* deal with hub status changes */
                if (test_and_clear_bit(0, hub->event_bits) == 0)
                        ;       /* do nothing */
                else if (hub_hub_status(hub, &hubstatus, &hubchange) < 0)
                        dev_err (hub_dev, "get_hub_status failed\n");
                else {
                        if (hubchange & HUB_CHANGE_LOCAL_POWER) {
                                dev_dbg (hub_dev, "power change\n");
                                clear_hub_feature(hdev, C_HUB_LOCAL_POWER);
                                if (hubstatus & HUB_STATUS_LOCAL_POWER)
                                        /* FIXME: Is this always true? */
                                        hub->limited_power = 0;
                                else
                                        hub->limited_power = 1;
                        }
                        if (hubchange & HUB_CHANGE_OVERCURRENT) {
                                dev_dbg (hub_dev, "overcurrent change\n");
                                msleep(500);    /* Cool down */
                                clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
                                hub_power_on(hub);
                        }
                }

                hub->activating = 0;

                /* If this is a root hub, tell the HCD it's okay to
                 * re-enable port-change interrupts now. */
                if (!hdev->parent && !hub->busy_bits[0])
                        usb_enable_root_hub_irq(hdev->bus);

loop_autopm:
                /* Allow autosuspend if we're not going to run again */
                if (list_empty(&hub->event_list))
                        usb_autopm_enable(intf);
loop:
                usb_unlock_device(hdev);
                usb_put_intf(intf);

        } /* end while (1) */
}

static int hub_thread(void *__unused)
{
        do {
                hub_events();
                wait_event_interruptible(khubd_wait,
                                !list_empty(&hub_event_list) ||
                                kthread_should_stop());
                try_to_freeze();
        } while (!kthread_should_stop() || !list_empty(&hub_event_list));

        pr_debug("%s: khubd exiting\n", usbcore_name);
        return 0;
}

static struct usb_device_id hub_id_table [] = {
    { .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
      .bDeviceClass = USB_CLASS_HUB},
    { .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS,
      .bInterfaceClass = USB_CLASS_HUB},
    { }                                         /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, hub_id_table);

static struct usb_driver hub_driver = {
        .name =         "hub",
        .probe =        hub_probe,
        .disconnect =   hub_disconnect,
        .suspend =      hub_suspend,
        .resume =       hub_resume,
        .pre_reset =    hub_pre_reset,
        .post_reset =   hub_post_reset,
        .ioctl =        hub_ioctl,
        .id_table =     hub_id_table,
        .supports_autosuspend = 1,
};

int usb_hub_init(void)
{
        if (usb_register(&hub_driver) < 0) {
                printk(KERN_ERR "%s: can't register hub driver\n",
                        usbcore_name);
                return -1;
        }

        khubd_task = kthread_run(hub_thread, NULL, "khubd");
        if (!IS_ERR(khubd_task))
                return 0;

        /* Fall through if kernel_thread failed */
        usb_deregister(&hub_driver);
        printk(KERN_ERR "%s: can't start khubd\n", usbcore_name);

        return -1;
}

void usb_hub_cleanup(void)
{
        kthread_stop(khubd_task);

        /*
         * Hub resources are freed for us by usb_deregister. It calls
         * usb_driver_purge on every device which in turn calls that
         * devices disconnect function if it is using this driver.
         * The hub_disconnect function takes care of releasing the
         * individual hub resources. -greg
         */
        usb_deregister(&hub_driver);
} /* usb_hub_cleanup() */

static int config_descriptors_changed(struct usb_device *udev)
{
        unsigned                        index;
        unsigned                        len = 0;
        struct usb_config_descriptor    *buf;

        for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
                if (len < le16_to_cpu(udev->config[index].desc.wTotalLength))
                        len = le16_to_cpu(udev->config[index].desc.wTotalLength);
        }
        buf = kmalloc (len, SLAB_KERNEL);
        if (buf == NULL) {
                dev_err(&udev->dev, "no mem to re-read configs after reset\n");
                /* assume the worst */
                return 1;
        }
        for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
                int length;
                int old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);

                length = usb_get_descriptor(udev, USB_DT_CONFIG, index, buf,
                                old_length);
                if (length < old_length) {
                        dev_dbg(&udev->dev, "config index %d, error %d\n",
                                        index, length);
                        break;
                }
                if (memcmp (buf, udev->rawdescriptors[index], old_length)
                                != 0) {
                        dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
                                index, buf->bConfigurationValue);
                        break;
                }
        }
        kfree(buf);
        return index != udev->descriptor.bNumConfigurations;
}

/**
 * usb_reset_device - perform a USB port reset to reinitialize a device
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * WARNING - don't use this routine to reset a composite device
 * (one with multiple interfaces owned by separate drivers)!
 * Use usb_reset_composite_device() instead.
 *
 * Do a port reset, reassign the device's address, and establish its
 * former operating configuration.  If the reset fails, or the device's
 * descriptors change from their values before the reset, or the original
 * configuration and altsettings cannot be restored, a flag will be set
 * telling khubd to pretend the device has been disconnected and then
 * re-connected.  All drivers will be unbound, and the device will be
 * re-enumerated and probed all over again.
 *
 * Returns 0 if the reset succeeded, -ENODEV if the device has been
 * flagged for logical disconnection, or some other negative error code
 * if the reset wasn't even attempted.
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 */
int usb_reset_device(struct usb_device *udev)
{
        struct usb_device               *parent_hdev = udev->parent;
        struct usb_hub                  *parent_hub;
        struct usb_device_descriptor    descriptor = udev->descriptor;
        int                             i, ret = 0;
        int                             port1 = udev->portnum;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                                udev->state);
                return -EINVAL;
        }

        if (!parent_hdev) {
                /* this requires hcd-specific logic; see OHCI hc_restart() */
                dev_dbg(&udev->dev, "%s for root hub!\n", __FUNCTION__);
                return -EISDIR;
        }
        parent_hub = hdev_to_hub(parent_hdev);

        set_bit(port1, parent_hub->busy_bits);
        for (i = 0; i < SET_CONFIG_TRIES; ++i) {

                /* ep0 maxpacket size may change; let the HCD know about it.
                 * Other endpoints will be handled by re-enumeration. */
                ep0_reinit(udev);
                ret = hub_port_init(parent_hub, udev, port1, i);
                if (ret >= 0)
                        break;
        }
        clear_bit(port1, parent_hub->busy_bits);
        if (!parent_hdev->parent && !parent_hub->busy_bits[0])
                usb_enable_root_hub_irq(parent_hdev->bus);

        if (ret < 0)
                goto re_enumerate;
 
        /* Device might have changed firmware (DFU or similar) */
        if (memcmp(&udev->descriptor, &descriptor, sizeof descriptor)
                        || config_descriptors_changed (udev)) {
                dev_info(&udev->dev, "device firmware changed\n");
                udev->descriptor = descriptor;  /* for disconnect() calls */
                goto re_enumerate;
        }
  
        if (!udev->actconfig)
                goto done;

        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_SET_CONFIGURATION, 0,
                        udev->actconfig->desc.bConfigurationValue, 0,
                        NULL, 0, USB_CTRL_SET_TIMEOUT);
        if (ret < 0) {
                dev_err(&udev->dev,
                        "can't restore configuration #%d (error=%d)\n",
                        udev->actconfig->desc.bConfigurationValue, ret);
                goto re_enumerate;
        }
        usb_set_device_state(udev, USB_STATE_CONFIGURED);

        for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                struct usb_interface *intf = udev->actconfig->interface[i];
                struct usb_interface_descriptor *desc;

                /* set_interface resets host side toggle even
                 * for altsetting zero.  the interface may have no driver.
                 */
                desc = &intf->cur_altsetting->desc;
                ret = usb_set_interface(udev, desc->bInterfaceNumber,
                        desc->bAlternateSetting);
                if (ret < 0) {
                        dev_err(&udev->dev, "failed to restore interface %d "
                                "altsetting %d (error=%d)\n",
                                desc->bInterfaceNumber,
                                desc->bAlternateSetting,
                                ret);
                        goto re_enumerate;
                }
        }

done:
        return 0;
 
re_enumerate:
        hub_port_logical_disconnect(parent_hub, port1);
        return -ENODEV;
}
EXPORT_SYMBOL(usb_reset_device);

/**
 * usb_reset_composite_device - warn interface drivers and perform a USB port reset
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 * @iface: interface bound to the driver making the request (optional)
 *
 * Warns all drivers bound to registered interfaces (using their pre_reset
 * method), performs the port reset, and then lets the drivers know that
 * the reset is over (using their post_reset method).
 *
 * Return value is the same as for usb_reset_device().
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 *
 * The interface locks are acquired during the pre_reset stage and released
 * during the post_reset stage.  However if iface is not NULL and is
 * currently being probed, we assume that the caller already owns its
 * lock.
 */
int usb_reset_composite_device(struct usb_device *udev,
                struct usb_interface *iface)
{
        int ret;
        struct usb_host_config *config = udev->actconfig;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                                udev->state);
                return -EINVAL;
        }

        /* Prevent autosuspend during the reset */
        usb_autoresume_device(udev, 1);

        if (iface && iface->condition != USB_INTERFACE_BINDING)
                iface = NULL;

        if (config) {
                int i;
                struct usb_interface *cintf;
                struct usb_driver *drv;

                for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                        cintf = config->interface[i];
                        if (cintf != iface)
                                down(&cintf->dev.sem);
                        if (device_is_registered(&cintf->dev) &&
                                        cintf->dev.driver) {
                                drv = to_usb_driver(cintf->dev.driver);
                                if (drv->pre_reset)
                                        (drv->pre_reset)(cintf);
                        }
                }
        }

        ret = usb_reset_device(udev);

        if (config) {
                int i;
                struct usb_interface *cintf;
                struct usb_driver *drv;

                for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
                        cintf = config->interface[i];
                        if (device_is_registered(&cintf->dev) &&
                                        cintf->dev.driver) {
                                drv = to_usb_driver(cintf->dev.driver);
                                if (drv->post_reset)
                                        (drv->post_reset)(cintf);
                        }
                        if (cintf != iface)
                                up(&cintf->dev.sem);
                }
        }

        usb_autosuspend_device(udev, 1);
        return ret;
}
EXPORT_SYMBOL(usb_reset_composite_device);