hub.c

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/*
 * USB hub driver.
 *
 * (C) Copyright 1999 Linus Torvalds
 * (C) Copyright 1999 Johannes Erdfelt
 * (C) Copyright 1999 Gregory P. Smith
 * (C) Copyright 2001 Brad Hards ([email protected])
 *
 */

#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/ioctl.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/usb/hcd.h>
#include <linux/usb/otg.h>
#include <linux/usb/quirks.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/random.h>

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

#include "usb.h"

/* if we are in debug mode, always announce new devices */
#ifdef DEBUG
#ifndef CONFIG_USB_ANNOUNCE_NEW_DEVICES
#define CONFIG_USB_ANNOUNCE_NEW_DEVICES
#endif
#endif

struct usb_port {
    struct usb_device *child;
    struct device dev;
    struct dev_state *port_owner;
    enum usb_port_connect_type connect_type;
};

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

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

    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 */
    unsigned long       removed_bits[1]; /* ports with a "removed"
                            device present */
    unsigned long       wakeup_bits[1]; /* ports that have signaled
                            remote wakeup */
#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        disconnected:1;

    unsigned        has_indicators:1;
    u8          indicator[USB_MAXCHILDREN];
    struct delayed_work leds;
    struct delayed_work init_work;
    struct usb_port     **ports;
};

static inline int hub_is_superspeed(struct usb_device *hdev)
{
    return (hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS);
}

/* 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;

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

/*
 * Device SATA8000 FW1.0 from DATAST0R Technology Corp requires about
 * 10 seconds to send reply for the initial 64-byte descriptor request.
 */
/* define initial 64-byte descriptor request timeout in milliseconds */
static int initial_descriptor_timeout = USB_CTRL_GET_TIMEOUT;
module_param(initial_descriptor_timeout, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(initial_descriptor_timeout,
        "initial 64-byte descriptor request timeout in milliseconds "
        "(default 5000 - 5.0 seconds)");

/*
 * 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 bool 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 bool 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");

/* Mutual exclusion for EHCI CF initialization.  This interferes with
 * port reset on some companion controllers.
 */
DECLARE_RWSEM(ehci_cf_port_reset_rwsem);
EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem);

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

#define to_usb_port(_dev) \
    container_of(_dev, struct usb_port, dev)

static int usb_reset_and_verify_device(struct usb_device *udev);

static inline char *portspeed(struct usb_hub *hub, int portstatus)
{
    if (hub_is_superspeed(hub->hdev))
        return "5.0 Gb/s";
    if (portstatus & USB_PORT_STAT_HIGH_SPEED)
            return "480 Mb/s";
    else if (portstatus & USB_PORT_STAT_LOW_SPEED)
        return "1.5 Mb/s";
    else
        return "12 Mb/s";
}

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

static int usb_device_supports_lpm(struct usb_device *udev)
{
    /* USB 2.1 (and greater) devices indicate LPM support through
     * their USB 2.0 Extended Capabilities BOS descriptor.
     */
    if (udev->speed == USB_SPEED_HIGH) {
        if (udev->bos->ext_cap &&
            (USB_LPM_SUPPORT &
             le32_to_cpu(udev->bos->ext_cap->bmAttributes)))
            return 1;
        return 0;
    }

    /* All USB 3.0 must support LPM, but we need their max exit latency
     * information from the SuperSpeed Extended Capabilities BOS descriptor.
     */
    if (!udev->bos->ss_cap) {
        dev_warn(&udev->dev, "No LPM exit latency info found.  "
                "Power management will be impacted.\n");
        return 0;
    }
    if (udev->parent->lpm_capable)
        return 1;

    dev_warn(&udev->dev, "Parent hub missing LPM exit latency info.  "
            "Power management will be impacted.\n");
    return 0;
}

/*
 * Set the Maximum Exit Latency (MEL) for the host to initiate a transition from
 * either U1 or U2.
 */
static void usb_set_lpm_mel(struct usb_device *udev,
        struct usb3_lpm_parameters *udev_lpm_params,
        unsigned int udev_exit_latency,
        struct usb_hub *hub,
        struct usb3_lpm_parameters *hub_lpm_params,
        unsigned int hub_exit_latency)
{
    unsigned int total_mel;
    unsigned int device_mel;
    unsigned int hub_mel;

    /*
     * Calculate the time it takes to transition all links from the roothub
     * to the parent hub into U0.  The parent hub must then decode the
     * packet (hub header decode latency) to figure out which port it was
     * bound for.
     *
     * The Hub Header decode latency is expressed in 0.1us intervals (0x1
     * means 0.1us).  Multiply that by 100 to get nanoseconds.
     */
    total_mel = hub_lpm_params->mel +
        (hub->descriptor->u.ss.bHubHdrDecLat * 100);

    /*
     * How long will it take to transition the downstream hub's port into
     * U0?  The greater of either the hub exit latency or the device exit
     * latency.
     *
     * The BOS U1/U2 exit latencies are expressed in 1us intervals.
     * Multiply that by 1000 to get nanoseconds.
     */
    device_mel = udev_exit_latency * 1000;
    hub_mel = hub_exit_latency * 1000;
    if (device_mel > hub_mel)
        total_mel += device_mel;
    else
        total_mel += hub_mel;

    udev_lpm_params->mel = total_mel;
}

/*
 * Set the maximum Device to Host Exit Latency (PEL) for the device to initiate
 * a transition from either U1 or U2.
 */
static void usb_set_lpm_pel(struct usb_device *udev,
        struct usb3_lpm_parameters *udev_lpm_params,
        unsigned int udev_exit_latency,
        struct usb_hub *hub,
        struct usb3_lpm_parameters *hub_lpm_params,
        unsigned int hub_exit_latency,
        unsigned int port_to_port_exit_latency)
{
    unsigned int first_link_pel;
    unsigned int hub_pel;

    /*
     * First, the device sends an LFPS to transition the link between the
     * device and the parent hub into U0.  The exit latency is the bigger of
     * the device exit latency or the hub exit latency.
     */
    if (udev_exit_latency > hub_exit_latency)
        first_link_pel = udev_exit_latency * 1000;
    else
        first_link_pel = hub_exit_latency * 1000;

    /*
     * When the hub starts to receive the LFPS, there is a slight delay for
     * it to figure out that one of the ports is sending an LFPS.  Then it
     * will forward the LFPS to its upstream link.  The exit latency is the
     * delay, plus the PEL that we calculated for this hub.
     */
    hub_pel = port_to_port_exit_latency * 1000 + hub_lpm_params->pel;

    /*
     * According to figure C-7 in the USB 3.0 spec, the PEL for this device
     * is the greater of the two exit latencies.
     */
    if (first_link_pel > hub_pel)
        udev_lpm_params->pel = first_link_pel;
    else
        udev_lpm_params->pel = hub_pel;
}

/*
 * Set the System Exit Latency (SEL) to indicate the total worst-case time from
 * when a device initiates a transition to U0, until when it will receive the
 * first packet from the host controller.
 *
 * Section C.1.5.1 describes the four components to this:
 *  - t1: device PEL
 *  - t2: time for the ERDY to make it from the device to the host.
 *  - t3: a host-specific delay to process the ERDY.
 *  - t4: time for the packet to make it from the host to the device.
 *
 * t3 is specific to both the xHCI host and the platform the host is integrated
 * into.  The Intel HW folks have said it's negligible, FIXME if a different
 * vendor says otherwise.
 */
static void usb_set_lpm_sel(struct usb_device *udev,
        struct usb3_lpm_parameters *udev_lpm_params)
{
    struct usb_device *parent;
    unsigned int num_hubs;
    unsigned int total_sel;

    /* t1 = device PEL */
    total_sel = udev_lpm_params->pel;
    /* How many external hubs are in between the device & the root port. */
    for (parent = udev->parent, num_hubs = 0; parent->parent;
            parent = parent->parent)
        num_hubs++;
    /* t2 = 2.1us + 250ns * (num_hubs - 1) */
    if (num_hubs > 0)
        total_sel += 2100 + 250 * (num_hubs - 1);

    /* t4 = 250ns * num_hubs */
    total_sel += 250 * num_hubs;

    udev_lpm_params->sel = total_sel;
}

static void usb_set_lpm_parameters(struct usb_device *udev)
{
    struct usb_hub *hub;
    unsigned int port_to_port_delay;
    unsigned int udev_u1_del;
    unsigned int udev_u2_del;
    unsigned int hub_u1_del;
    unsigned int hub_u2_del;

    if (!udev->lpm_capable || udev->speed != USB_SPEED_SUPER)
        return;

    hub = hdev_to_hub(udev->parent);
    /* It doesn't take time to transition the roothub into U0, since it
     * doesn't have an upstream link.
     */
    if (!hub)
        return;

    udev_u1_del = udev->bos->ss_cap->bU1devExitLat;
    udev_u2_del = udev->bos->ss_cap->bU2DevExitLat;
    hub_u1_del = udev->parent->bos->ss_cap->bU1devExitLat;
    hub_u2_del = udev->parent->bos->ss_cap->bU2DevExitLat;

    usb_set_lpm_mel(udev, &udev->u1_params, udev_u1_del,
            hub, &udev->parent->u1_params, hub_u1_del);

    usb_set_lpm_mel(udev, &udev->u2_params, udev_u2_del,
            hub, &udev->parent->u2_params, hub_u2_del);

    /*
     * Appendix C, section C.2.2.2, says that there is a slight delay from
     * when the parent hub notices the downstream port is trying to
     * transition to U0 to when the hub initiates a U0 transition on its
     * upstream port.  The section says the delays are tPort2PortU1EL and
     * tPort2PortU2EL, but it doesn't define what they are.
     *
     * The hub chapter, sections 10.4.2.4 and 10.4.2.5 seem to be talking
     * about the same delays.  Use the maximum delay calculations from those
     * sections.  For U1, it's tHubPort2PortExitLat, which is 1us max.  For
     * U2, it's tHubPort2PortExitLat + U2DevExitLat - U1DevExitLat.  I
     * assume the device exit latencies they are talking about are the hub
     * exit latencies.
     *
     * What do we do if the U2 exit latency is less than the U1 exit
     * latency?  It's possible, although not likely...
     */
    port_to_port_delay = 1;

    usb_set_lpm_pel(udev, &udev->u1_params, udev_u1_del,
            hub, &udev->parent->u1_params, hub_u1_del,
            port_to_port_delay);

    if (hub_u2_del > hub_u1_del)
        port_to_port_delay = 1 + hub_u2_del - hub_u1_del;
    else
        port_to_port_delay = 1 + hub_u1_del;

    usb_set_lpm_pel(udev, &udev->u2_params, udev_u2_del,
            hub, &udev->parent->u2_params, hub_u2_del,
            port_to_port_delay);

    /* Now that we've got PEL, calculate SEL. */
    usb_set_lpm_sel(udev, &udev->u1_params);
    usb_set_lpm_sel(udev, &udev->u2_params);
}

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

    if (hub_is_superspeed(hdev)) {
        dtype = USB_DT_SS_HUB;
        size = USB_DT_SS_HUB_SIZE;
    } else {
        dtype = USB_DT_HUB;
        size = sizeof(struct usb_hub_descriptor);
    }

    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,
            dtype << 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 (struct work_struct *work)
{
    struct usb_hub      *hub =
        container_of(work, struct usb_hub, leds.work);
    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 || status == -EPIPE); 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 || status == -EPIPE); 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 int hub_port_status(struct usb_hub *hub, int port1,
        u16 *status, u16 *change)
{
    int ret;

    mutex_lock(&hub->status_mutex);
    ret = get_port_status(hub->hdev, port1, &hub->status->port);
    if (ret < 4) {
        dev_err(hub->intfdev,
            "%s failed (err = %d)\n", __func__, ret);
        if (ret >= 0)
            ret = -EIO;
    } else {
        *status = le16_to_cpu(hub->status->port.wPortStatus);
        *change = le16_to_cpu(hub->status->port.wPortChange);

        ret = 0;
    }
    mutex_unlock(&hub->status_mutex);
    return ret;
}

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

    spin_lock_irqsave(&hub_event_lock, flags);
    if (!hub->disconnected && list_empty(&hub->event_list)) {
        list_add_tail(&hub->event_list, &hub_event_list);

        /* Suppress autosuspend until khubd runs */
        usb_autopm_get_interface_no_resume(
                to_usb_interface(hub->intfdev));
        wake_up(&khubd_wait);
    }
    spin_unlock_irqrestore(&hub_event_lock, flags);
}

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

    if (hub)
        kick_khubd(hub);
}

/*
 * Let the USB core know that a USB 3.0 device has sent a Function Wake Device
 * Notification, which indicates it had initiated remote wakeup.
 *
 * USB 3.0 hubs do not report the port link state change from U3 to U0 when the
 * device initiates resume, so the USB core will not receive notice of the
 * resume through the normal hub interrupt URB.
 */
void usb_wakeup_notification(struct usb_device *hdev,
        unsigned int portnum)
{
    struct usb_hub *hub;

    if (!hdev)
        return;

    hub = hdev_to_hub(hdev);
    if (hub) {
        set_bit(portnum, hub->wakeup_bits);
        kick_khubd(hub);
    }
}
EXPORT_SYMBOL_GPL(usb_wakeup_notification);

/* 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 = urb->status;
    unsigned i;
    unsigned long bits;

    switch (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", status);
        if ((++hub->nerrors < 10) || hub->error)
            goto resubmit;
        hub->error = 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_sndctrlpipe(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_work(struct work_struct *work)
{
    struct usb_hub      *hub =
        container_of(work, struct usb_hub, tt.clear_work);
    unsigned long       flags;
    int         limit = 100;

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

        if (!hub->quiescing && --limit < 0)
            break;

        next = hub->tt.clear_list.next;
        clear = list_entry (next, 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);
        if (status)
            dev_err (&hdev->dev,
                "clear tt %d (%04x) error %d\n",
                clear->tt, clear->devinfo, status);

        /* Tell the HCD, even if the operation failed */
        drv = clear->hcd->driver;
        if (drv->clear_tt_buffer_complete)
            (drv->clear_tt_buffer_complete)(clear->hcd, clear->ep);

        kfree(clear);
        spin_lock_irqsave(&hub->tt.lock, flags);
    }
    spin_unlock_irqrestore (&hub->tt.lock, flags);
}

int usb_hub_clear_tt_buffer(struct urb *urb)
{
    struct usb_device   *udev = urb->dev;
    int         pipe = urb->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, GFP_ATOMIC)) == NULL) {
        dev_err (&udev->dev, "can't save CLEAR_TT_BUFFER state\n");
        /* FIXME recover somehow ... RESET_TT? */
        return -ENOMEM;
    }

    /* 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;

    /* info for completion callback */
    clear->hcd = bus_to_hcd(udev->bus);
    clear->ep = urb->ep;

    /* 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->clear_work);
    spin_unlock_irqrestore (&tt->lock, flags);
    return 0;
}
EXPORT_SYMBOL_GPL(usb_hub_clear_tt_buffer);

/* If do_delay is false, return the number of milliseconds the caller
 * needs to delay.
 */
static unsigned hub_power_on(struct usb_hub *hub, bool do_delay)
{
    int port1;
    unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2;
    unsigned delay;
    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 */
    delay = max(pgood_delay, (unsigned) 100);
    if (do_delay)
        msleep(delay);
    return delay;
}

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

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

static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
{
    struct usb_device *hdev = hub->hdev;
    int ret = 0;

    if (hub->ports[port1 - 1]->child && set_state)
        usb_set_device_state(hub->ports[port1 - 1]->child,
                USB_STATE_NOTATTACHED);
    if (!hub->error && !hub_is_superspeed(hub->hdev))
        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;
}

/*
 * Disable a port and mark a logical connect-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);
}

int usb_remove_device(struct usb_device *udev)
{
    struct usb_hub *hub;
    struct usb_interface *intf;

    if (!udev->parent)  /* Can't remove a root hub */
        return -EINVAL;
    hub = hdev_to_hub(udev->parent);
    intf = to_usb_interface(hub->intfdev);

    usb_autopm_get_interface(intf);
    set_bit(udev->portnum, hub->removed_bits);
    hub_port_logical_disconnect(hub, udev->portnum);
    usb_autopm_put_interface(intf);
    return 0;
}

enum hub_activation_type {
    HUB_INIT, HUB_INIT2, HUB_INIT3,     /* INITs must come first */
    HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
};

static void hub_init_func2(struct work_struct *ws);
static void hub_init_func3(struct work_struct *ws);

static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
{
    struct usb_device *hdev = hub->hdev;
    struct usb_hcd *hcd;
    int ret;
    int port1;
    int status;
    bool need_debounce_delay = false;
    unsigned delay;

    /* Continue a partial initialization */
    if (type == HUB_INIT2)
        goto init2;
    if (type == HUB_INIT3)
        goto init3;

    /* The superspeed hub except for root hub has to use Hub Depth
     * value as an offset into the route string to locate the bits
     * it uses to determine the downstream port number. So hub driver
     * should send a set hub depth request to superspeed hub after
     * the superspeed hub is set configuration in initialization or
     * reset procedure.
     *
     * After a resume, port power should still be on.
     * For any other type of activation, turn it on.
     */
    if (type != HUB_RESUME) {
        if (hdev->parent && hub_is_superspeed(hdev)) {
            ret = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                    HUB_SET_DEPTH, USB_RT_HUB,
                    hdev->level - 1, 0, NULL, 0,
                    USB_CTRL_SET_TIMEOUT);
            if (ret < 0)
                dev_err(hub->intfdev,
                        "set hub depth failed\n");
        }

        /* Speed up system boot by using a delayed_work for the
         * hub's initial power-up delays.  This is pretty awkward
         * and the implementation looks like a home-brewed sort of
         * setjmp/longjmp, but it saves at least 100 ms for each
         * root hub (assuming usbcore is compiled into the kernel
         * rather than as a module).  It adds up.
         *
         * This can't be done for HUB_RESUME or HUB_RESET_RESUME
         * because for those activation types the ports have to be
         * operational when we return.  In theory this could be done
         * for HUB_POST_RESET, but it's easier not to.
         */
        if (type == HUB_INIT) {
            delay = hub_power_on(hub, false);
            PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func2);
            schedule_delayed_work(&hub->init_work,
                    msecs_to_jiffies(delay));

            /* Suppress autosuspend until init is done */
            usb_autopm_get_interface_no_resume(
                    to_usb_interface(hub->intfdev));
            return;     /* Continues at init2: below */
        } else if (type == HUB_RESET_RESUME) {
            /* The internal host controller state for the hub device
             * may be gone after a host power loss on system resume.
             * Update the device's info so the HW knows it's a hub.
             */
            hcd = bus_to_hcd(hdev->bus);
            if (hcd->driver->update_hub_device) {
                ret = hcd->driver->update_hub_device(hcd, hdev,
                        &hub->tt, GFP_NOIO);
                if (ret < 0) {
                    dev_err(hub->intfdev, "Host not "
                            "accepting hub info "
                            "update.\n");
                    dev_err(hub->intfdev, "LS/FS devices "
                            "and hubs may not work "
                            "under this hub\n.");
                }
            }
            hub_power_on(hub, true);
        } else {
            hub_power_on(hub, true);
        }
    }
 init2:

    /* Check each port and set hub->change_bits to let khubd know
     * which ports need attention.
     */
    for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
        struct usb_device *udev = hub->ports[port1 - 1]->child;
        u16 portstatus, portchange;

        portstatus = portchange = 0;
        status = hub_port_status(hub, port1, &portstatus, &portchange);
        if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
            dev_dbg(hub->intfdev,
                    "port %d: status %04x change %04x\n",
                    port1, portstatus, portchange);

        /* After anything other than HUB_RESUME (i.e., initialization
         * or any sort of reset), every port should be disabled.
         * Unconnected ports should likewise be disabled (paranoia),
         * and so should ports for which we have no usb_device.
         */
        if ((portstatus & USB_PORT_STAT_ENABLE) && (
                type != HUB_RESUME ||
                !(portstatus & USB_PORT_STAT_CONNECTION) ||
                !udev ||
                udev->state == USB_STATE_NOTATTACHED)) {
            /*
             * USB3 protocol ports will automatically transition
             * to Enabled state when detect an USB3.0 device attach.
             * Do not disable USB3 protocol ports.
             */
            if (!hub_is_superspeed(hdev)) {
                clear_port_feature(hdev, port1,
                           USB_PORT_FEAT_ENABLE);
                portstatus &= ~USB_PORT_STAT_ENABLE;
            } else {
                /* Pretend that power was lost for USB3 devs */
                portstatus &= ~USB_PORT_STAT_ENABLE;
            }
        }

        /* Clear status-change flags; we'll debounce later */
        if (portchange & USB_PORT_STAT_C_CONNECTION) {
            need_debounce_delay = true;
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_CONNECTION);
        }
        if (portchange & USB_PORT_STAT_C_ENABLE) {
            need_debounce_delay = true;
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_ENABLE);
        }
        if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
                hub_is_superspeed(hub->hdev)) {
            need_debounce_delay = true;
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_BH_PORT_RESET);
        }
        /* We can forget about a "removed" device when there's a
         * physical disconnect or the connect status changes.
         */
        if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                (portchange & USB_PORT_STAT_C_CONNECTION))
            clear_bit(port1, hub->removed_bits);

        if (!udev || udev->state == USB_STATE_NOTATTACHED) {
            /* Tell khubd to disconnect the device or
             * check for a new connection
             */
            if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
                set_bit(port1, hub->change_bits);

        } else if (portstatus & USB_PORT_STAT_ENABLE) {
            bool port_resumed = (portstatus &
                    USB_PORT_STAT_LINK_STATE) ==
                USB_SS_PORT_LS_U0;
            /* The power session apparently survived the resume.
             * If there was an overcurrent or suspend change
             * (i.e., remote wakeup request), have khubd
             * take care of it.  Look at the port link state
             * for USB 3.0 hubs, since they don't have a suspend
             * change bit, and they don't set the port link change
             * bit on device-initiated resume.
             */
            if (portchange || (hub_is_superspeed(hub->hdev) &&
                        port_resumed))
                set_bit(port1, hub->change_bits);

        } else if (udev->persist_enabled) {
#ifdef CONFIG_PM
            udev->reset_resume = 1;
#endif
            set_bit(port1, hub->change_bits);

        } else {
            /* The power session is gone; tell khubd */
            usb_set_device_state(udev, USB_STATE_NOTATTACHED);
            set_bit(port1, hub->change_bits);
        }
    }

    /* If no port-status-change flags were set, we don't need any
     * debouncing.  If flags were set we can try to debounce the
     * ports all at once right now, instead of letting khubd do them
     * one at a time later on.
     *
     * If any port-status changes do occur during this delay, khubd
     * will see them later and handle them normally.
     */
    if (need_debounce_delay) {
        delay = HUB_DEBOUNCE_STABLE;

        /* Don't do a long sleep inside a workqueue routine */
        if (type == HUB_INIT2) {
            PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func3);
            schedule_delayed_work(&hub->init_work,
                    msecs_to_jiffies(delay));
            return;     /* Continues at init3: below */
        } else {
            msleep(delay);
        }
    }
 init3:
    hub->quiescing = 0;

    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 that need attention */
    kick_khubd(hub);

    /* Allow autosuspend if it was suppressed */
    if (type <= HUB_INIT3)
        usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
}

/* Implement the continuations for the delays above */
static void hub_init_func2(struct work_struct *ws)
{
    struct usb_hub *hub = container_of(ws, struct usb_hub, init_work.work);

    hub_activate(hub, HUB_INIT2);
}

static void hub_init_func3(struct work_struct *ws)
{
    struct usb_hub *hub = container_of(ws, struct usb_hub, init_work.work);

    hub_activate(hub, HUB_INIT3);
}

enum hub_quiescing_type {
    HUB_DISCONNECT, HUB_PRE_RESET, HUB_SUSPEND
};

static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
{
    struct usb_device *hdev = hub->hdev;
    int i;

    cancel_delayed_work_sync(&hub->init_work);

    /* khubd and related activity won't re-trigger */
    hub->quiescing = 1;

    if (type != HUB_SUSPEND) {
        /* Disconnect all the children */
        for (i = 0; i < hdev->maxchild; ++i) {
            if (hub->ports[i]->child)
                usb_disconnect(&hub->ports[i]->child);
        }
    }

    /* Stop khubd and related activity */
    usb_kill_urb(hub->urb);
    if (hub->has_indicators)
        cancel_delayed_work_sync(&hub->leds);
    if (hub->tt.hub)
        flush_work(&hub->tt.clear_work);
}

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

    hub_quiesce(hub, HUB_PRE_RESET);
    return 0;
}

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

    hub_activate(hub, HUB_POST_RESET);
    return 0;
}

static void usb_port_device_release(struct device *dev)
{
    struct usb_port *port_dev = to_usb_port(dev);

    kfree(port_dev);
}

static void usb_hub_remove_port_device(struct usb_hub *hub,
                       int port1)
{
    device_unregister(&hub->ports[port1 - 1]->dev);
}

struct device_type usb_port_device_type = {
    .name =     "usb_port",
    .release =  usb_port_device_release,
};

static int usb_hub_create_port_device(struct usb_hub *hub,
                      int port1)
{
    struct usb_port *port_dev = NULL;
    int retval;

    port_dev = kzalloc(sizeof(*port_dev), GFP_KERNEL);
    if (!port_dev) {
        retval = -ENOMEM;
        goto exit;
    }

    hub->ports[port1 - 1] = port_dev;
    port_dev->dev.parent = hub->intfdev;
    port_dev->dev.type = &usb_port_device_type;
    dev_set_name(&port_dev->dev, "port%d", port1);

    retval = device_register(&port_dev->dev);
    if (retval)
        goto error_register;
    return 0;

error_register:
    put_device(&port_dev->dev);
exit:
    return retval;
}

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

    hub->buffer = kmalloc(sizeof(*hub->buffer), GFP_KERNEL);
    if (!hub->buffer) {
        ret = -ENOMEM;
        goto fail;
    }

    hub->status = kmalloc(sizeof(*hub->status), GFP_KERNEL);
    if (!hub->status) {
        ret = -ENOMEM;
        goto fail;
    }
    mutex_init(&hub->status_mutex);

    hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
    if (!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);
    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");

    hub->ports = kzalloc(hdev->maxchild * sizeof(struct usb_port *),
                 GFP_KERNEL);
    if (!hub->ports) {
        ret = -ENOMEM;
        goto fail;
    }

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

    /* FIXME for USB 3.0, skip for now */
    if ((wHubCharacteristics & HUB_CHAR_COMPOUND) &&
            !(hub_is_superspeed(hdev))) {
        int i;
        char    portstr [USB_MAXCHILDREN + 1];

        for (i = 0; i < hdev->maxchild; i++)
            portstr[i] = hub->descriptor->u.hs.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 HUB_CHAR_COMMON_LPSM:
        dev_dbg(hub_dev, "ganged power switching\n");
        break;
    case HUB_CHAR_INDV_PORT_LPSM:
        dev_dbg(hub_dev, "individual port power switching\n");
        break;
    case HUB_CHAR_NO_LPSM:
    case HUB_CHAR_LPSM:
        dev_dbg(hub_dev, "no power switching (usb 1.0)\n");
        break;
    }

    switch (wHubCharacteristics & HUB_CHAR_OCPM) {
    case HUB_CHAR_COMMON_OCPM:
        dev_dbg(hub_dev, "global over-current protection\n");
        break;
    case HUB_CHAR_INDV_PORT_OCPM:
        dev_dbg(hub_dev, "individual port over-current protection\n");
        break;
    case HUB_CHAR_NO_OCPM:
    case HUB_CHAR_OCPM:
        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.clear_work, hub_tt_work);
    switch (hdev->descriptor.bDeviceProtocol) {
    case USB_HUB_PR_FS:
        break;
    case USB_HUB_PR_HS_SINGLE_TT:
        dev_dbg(hub_dev, "Single TT\n");
        hub->tt.hub = hdev;
        break;
    case USB_HUB_PR_HS_MULTI_TT:
        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;
    case USB_HUB_PR_SS:
        /* USB 3.0 hubs don't have a TT */
        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);

    /* Update the HCD's internal representation of this hub before khubd
     * starts getting port status changes for devices under the hub.
     */
    hcd = bus_to_hcd(hdev->bus);
    if (hcd->driver->update_hub_device) {
        ret = hcd->driver->update_hub_device(hcd, hdev,
                &hub->tt, GFP_KERNEL);
        if (ret < 0) {
            message = "can't update HCD hub info";
            goto fail;
        }
    }

    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) {
        ret = -ENOMEM;
        goto fail;
    }

    usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
        hub, endpoint->bInterval);

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

    for (i = 0; i < hdev->maxchild; i++)
        if (usb_hub_create_port_device(hub, i + 1) < 0)
            dev_err(hub->intfdev,
                "couldn't create port%d device.\n", i + 1);

    hub_activate(hub, HUB_INIT);
    return 0;

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

static void hub_release(struct kref *kref)
{
    struct usb_hub *hub = container_of(kref, struct usb_hub, kref);

    usb_put_intf(to_usb_interface(hub->intfdev));
    kfree(hub);
}

static unsigned highspeed_hubs;

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

    /* Take the hub off the event list and don't let it be added again */
    spin_lock_irq(&hub_event_lock);
    if (!list_empty(&hub->event_list)) {
        list_del_init(&hub->event_list);
        usb_autopm_put_interface_no_suspend(intf);
    }
    hub->disconnected = 1;
    spin_unlock_irq(&hub_event_lock);

    /* Disconnect all children and quiesce the hub */
    hub->error = 0;
    hub_quiesce(hub, HUB_DISCONNECT);

    usb_set_intfdata (intf, NULL);

    for (i = 0; i < hdev->maxchild; i++)
        usb_hub_remove_port_device(hub, i + 1);
    hub->hdev->maxchild = 0;

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

    usb_free_urb(hub->urb);
    kfree(hub->ports);
    kfree(hub->descriptor);
    kfree(hub->status);
    kfree(hub->buffer);

    kref_put(&hub->kref, hub_release);
}

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);

    /* Hubs have proper suspend/resume support. */
    usb_enable_autosuspend(hdev);

    if (hdev->level == MAX_TOPO_LEVEL) {
        dev_err(&intf->dev,
            "Unsupported bus topology: hub nested too deep\n");
        return -E2BIG;
    }

#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;
    }

    kref_init(&hub->kref);
    INIT_LIST_HEAD(&hub->event_list);
    hub->intfdev = &intf->dev;
    hub->hdev = hdev;
    INIT_DELAYED_WORK(&hub->leds, led_work);
    INIT_DELAYED_WORK(&hub->init_work, NULL);
    usb_get_intf(intf);

    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);
    struct usb_hub *hub = hdev_to_hub(hdev);

    /* 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 (hub->ports[i]->child == NULL)
                    info->port[i] = 0;
                else
                    info->port[i] =
                        hub->ports[i]->child->devnum;
            }
        }
        spin_unlock_irq(&device_state_lock);

        return info->nports + 1;
        }

    default:
        return -ENOSYS;
    }
}

/*
 * Allow user programs to claim ports on a hub.  When a device is attached
 * to one of these "claimed" ports, the program will "own" the device.
 */
static int find_port_owner(struct usb_device *hdev, unsigned port1,
        struct dev_state ***ppowner)
{
    if (hdev->state == USB_STATE_NOTATTACHED)
        return -ENODEV;
    if (port1 == 0 || port1 > hdev->maxchild)
        return -EINVAL;

    /* This assumes that devices not managed by the hub driver
     * will always have maxchild equal to 0.
     */
    *ppowner = &(hdev_to_hub(hdev)->ports[port1 - 1]->port_owner);
    return 0;
}

/* In the following three functions, the caller must hold hdev's lock */
int usb_hub_claim_port(struct usb_device *hdev, unsigned port1,
               struct dev_state *owner)
{
    int rc;
    struct dev_state **powner;

    rc = find_port_owner(hdev, port1, &powner);
    if (rc)
        return rc;
    if (*powner)
        return -EBUSY;
    *powner = owner;
    return rc;
}

int usb_hub_release_port(struct usb_device *hdev, unsigned port1,
             struct dev_state *owner)
{
    int rc;
    struct dev_state **powner;

    rc = find_port_owner(hdev, port1, &powner);
    if (rc)
        return rc;
    if (*powner != owner)
        return -ENOENT;
    *powner = NULL;
    return rc;
}

void usb_hub_release_all_ports(struct usb_device *hdev, struct dev_state *owner)
{
    struct usb_hub *hub = hdev_to_hub(hdev);
    int n;

    for (n = 0; n < hdev->maxchild; n++) {
        if (hub->ports[n]->port_owner == owner)
            hub->ports[n]->port_owner = NULL;
    }

}

/* The caller must hold udev's lock */
bool usb_device_is_owned(struct usb_device *udev)
{
    struct usb_hub *hub;

    if (udev->state == USB_STATE_NOTATTACHED || !udev->parent)
        return false;
    hub = hdev_to_hub(udev->parent);
    return !!hub->ports[udev->portnum - 1]->port_owner;
}

static void recursively_mark_NOTATTACHED(struct usb_device *udev)
{
    struct usb_hub *hub = hdev_to_hub(udev);
    int i;

    for (i = 0; i < udev->maxchild; ++i) {
        if (hub->ports[i]->child)
            recursively_mark_NOTATTACHED(hub->ports[i]->child);
    }
    if (udev->state == USB_STATE_SUSPENDED)
        udev->active_duration -= jiffies;
    udev->state = USB_STATE_NOTATTACHED;
}

void usb_set_device_state(struct usb_device *udev,
        enum usb_device_state new_state)
{
    unsigned long flags;
    int wakeup = -1;

    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)
                wakeup = udev->actconfig->desc.bmAttributes
                     & USB_CONFIG_ATT_WAKEUP;
            else
                wakeup = 0;
        }
        if (udev->state == USB_STATE_SUSPENDED &&
            new_state != USB_STATE_SUSPENDED)
            udev->active_duration -= jiffies;
        else if (new_state == USB_STATE_SUSPENDED &&
                udev->state != USB_STATE_SUSPENDED)
            udev->active_duration += jiffies;
        udev->state = new_state;
    } else
        recursively_mark_NOTATTACHED(udev);
    spin_unlock_irqrestore(&device_state_lock, flags);
    if (wakeup >= 0)
        device_set_wakeup_capable(&udev->dev, wakeup);
}
EXPORT_SYMBOL_GPL(usb_set_device_state);

/*
 * Choose a device number.
 *
 * Device numbers are used as filenames in usbfs.  On USB-1.1 and
 * USB-2.0 buses they are also used as device addresses, however on
 * USB-3.0 buses the address is assigned by the controller hardware
 * and it usually is not the same as the device number.
 *
 * WUSB devices are simple: they have no hubs behind, so the mapping
 * device <-> virtual port number becomes 1:1. Why? to simplify the
 * life of the device connection logic in
 * drivers/usb/wusbcore/devconnect.c. When we do the initial secret
 * handshake we need to assign a temporary address in the unauthorized
 * space. For simplicity we use the first virtual port number found to
 * be free [drivers/usb/wusbcore/devconnect.c:wusbhc_devconnect_ack()]
 * and that becomes it's address [X < 128] or its unauthorized address
 * [X | 0x80].
 *
 * We add 1 as an offset to the one-based USB-stack port number
 * (zero-based wusb virtual port index) for two reasons: (a) dev addr
 * 0 is reserved by USB for default address; (b) Linux's USB stack
 * uses always #1 for the root hub of the controller. So USB stack's
 * port #1, which is wusb virtual-port #0 has address #2.
 *
 * Devices connected under xHCI are not as simple.  The host controller
 * supports virtualization, so the hardware assigns device addresses and
 * the HCD must setup data structures before issuing a set address
 * command to the hardware.
 */
static void choose_devnum(struct usb_device *udev)
{
    int     devnum;
    struct usb_bus  *bus = udev->bus;

    /* If khubd ever becomes multithreaded, this will need a lock */
    if (udev->wusb) {
        devnum = udev->portnum + 1;
        BUG_ON(test_bit(devnum, bus->devmap.devicemap));
    } else {
        /* 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_devnum(struct usb_device *udev)
{
    if (udev->devnum > 0) {
        clear_bit(udev->devnum, udev->bus->devmap.devicemap);
        udev->devnum = -1;
    }
}

static void update_devnum(struct usb_device *udev, int devnum)
{
    /* The address for a WUSB device is managed by wusbcore. */
    if (!udev->wusb)
        udev->devnum = devnum;
}

static void hub_free_dev(struct usb_device *udev)
{
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);

    /* Root hubs aren't real devices, so don't free HCD resources */
    if (hcd->driver->free_dev && udev->parent)
        hcd->driver->free_dev(hcd, udev);
}

void usb_disconnect(struct usb_device **pdev)
{
    struct usb_device   *udev = *pdev;
    struct usb_hub      *hub = hdev_to_hub(udev);
    int         i;

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

    usb_lock_device(udev);

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

    /* 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_hcd_synchronize_unlinks(udev);

    usb_remove_ep_devs(&udev->ep0);
    usb_unlock_device(udev);

    /* Unregister the device.  The device driver is responsible
     * for de-configuring the device and invoking the remove-device
     * notifier chain (used by usbfs and possibly others).
     */
    device_del(&udev->dev);

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

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

    hub_free_dev(udev);

    put_device(&udev->dev);
}

#ifdef CONFIG_USB_ANNOUNCE_NEW_DEVICES
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);
}

static void announce_device(struct usb_device *udev)
{
    dev_info(&udev->dev, "New USB device found, idVendor=%04x, idProduct=%04x\n",
        le16_to_cpu(udev->descriptor.idVendor),
        le16_to_cpu(udev->descriptor.idProduct));
    dev_info(&udev->dev,
        "New USB 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);
}
#else
static inline void announce_device(struct usb_device *udev) { }
#endif

#ifdef  CONFIG_USB_OTG
#include "otg_whitelist.h"
#endif

static int usb_enumerate_device_otg(struct usb_device *udev)
{
    int err = 0;

#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 = NULL;
        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, PMSG_SUSPEND);
            if (err < 0)
                dev_dbg(&udev->dev, "HNP fail, %d\n", err);
        }
        err = -ENOTSUPP;
        goto fail;
    }
fail:
#endif
    return err;
}


static int usb_enumerate_device(struct usb_device *udev)
{
    int err;

    if (udev->config == NULL) {
        err = usb_get_configuration(udev);
        if (err < 0) {
            dev_err(&udev->dev, "can't read configurations, error %d\n",
                err);
            return err;
        }
    }
    if (udev->wusb == 1 && udev->authorized == 0) {
        udev->product = kstrdup("n/a (unauthorized)", GFP_KERNEL);
        udev->manufacturer = kstrdup("n/a (unauthorized)", GFP_KERNEL);
        udev->serial = kstrdup("n/a (unauthorized)", GFP_KERNEL);
    }
    else {
        /* 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);
    }
    err = usb_enumerate_device_otg(udev);
    if (err < 0)
        return err;

    usb_detect_interface_quirks(udev);

    return 0;
}

static void set_usb_port_removable(struct usb_device *udev)
{
    struct usb_device *hdev = udev->parent;
    struct usb_hub *hub;
    u8 port = udev->portnum;
    u16 wHubCharacteristics;
    bool removable = true;

    if (!hdev)
        return;

    hub = hdev_to_hub(udev->parent);

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

    if (!(wHubCharacteristics & HUB_CHAR_COMPOUND))
        return;

    if (hub_is_superspeed(hdev)) {
        if (le16_to_cpu(hub->descriptor->u.ss.DeviceRemovable)
                & (1 << port))
            removable = false;
    } else {
        if (hub->descriptor->u.hs.DeviceRemovable[port / 8] & (1 << (port % 8)))
            removable = false;
    }

    if (removable)
        udev->removable = USB_DEVICE_REMOVABLE;
    else
        udev->removable = USB_DEVICE_FIXED;
}

int usb_new_device(struct usb_device *udev)
{
    int err;

    if (udev->parent) {
        /* Initialize non-root-hub device wakeup to disabled;
         * device (un)configuration controls wakeup capable
         * sysfs power/wakeup controls wakeup enabled/disabled
         */
        device_init_wakeup(&udev->dev, 0);
    }

    /* Tell the runtime-PM framework the device is active */
    pm_runtime_set_active(&udev->dev);
    pm_runtime_get_noresume(&udev->dev);
    pm_runtime_use_autosuspend(&udev->dev);
    pm_runtime_enable(&udev->dev);

    /* By default, forbid autosuspend for all devices.  It will be
     * allowed for hubs during binding.
     */
    usb_disable_autosuspend(udev);

    err = usb_enumerate_device(udev);   /* Read descriptors */
    if (err < 0)
        goto fail;
    dev_dbg(&udev->dev, "udev %d, busnum %d, minor = %d\n",
            udev->devnum, udev->bus->busnum,
            (((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
    /* export the usbdev device-node for libusb */
    udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
            (((udev->bus->busnum-1) * 128) + (udev->devnum-1)));

    /* Tell the world! */
    announce_device(udev);

    if (udev->serial)
        add_device_randomness(udev->serial, strlen(udev->serial));
    if (udev->product)
        add_device_randomness(udev->product, strlen(udev->product));
    if (udev->manufacturer)
        add_device_randomness(udev->manufacturer,
                      strlen(udev->manufacturer));

    device_enable_async_suspend(&udev->dev);

    /*
     * check whether the hub marks this port as non-removable. Do it
     * now so that platform-specific data can override it in
     * device_add()
     */
    if (udev->parent)
        set_usb_port_removable(udev);

    /* Register the device.  The device driver is responsible
     * for configuring the device and invoking the add-device
     * notifier chain (used by usbfs and possibly others).
     */
    err = device_add(&udev->dev);
    if (err) {
        dev_err(&udev->dev, "can't device_add, error %d\n", err);
        goto fail;
    }

    (void) usb_create_ep_devs(&udev->dev, &udev->ep0, udev);
    usb_mark_last_busy(udev);
    pm_runtime_put_sync_autosuspend(&udev->dev);
    return err;

fail:
    usb_set_device_state(udev, USB_STATE_NOTATTACHED);
    pm_runtime_disable(&udev->dev);
    pm_runtime_set_suspended(&udev->dev);
    return err;
}


int usb_deauthorize_device(struct usb_device *usb_dev)
{
    usb_lock_device(usb_dev);
    if (usb_dev->authorized == 0)
        goto out_unauthorized;

    usb_dev->authorized = 0;
    usb_set_configuration(usb_dev, -1);

    kfree(usb_dev->product);
    usb_dev->product = kstrdup("n/a (unauthorized)", GFP_KERNEL);
    kfree(usb_dev->manufacturer);
    usb_dev->manufacturer = kstrdup("n/a (unauthorized)", GFP_KERNEL);
    kfree(usb_dev->serial);
    usb_dev->serial = kstrdup("n/a (unauthorized)", GFP_KERNEL);

    usb_destroy_configuration(usb_dev);
    usb_dev->descriptor.bNumConfigurations = 0;

out_unauthorized:
    usb_unlock_device(usb_dev);
    return 0;
}


int usb_authorize_device(struct usb_device *usb_dev)
{
    int result = 0, c;

    usb_lock_device(usb_dev);
    if (usb_dev->authorized == 1)
        goto out_authorized;

    result = usb_autoresume_device(usb_dev);
    if (result < 0) {
        dev_err(&usb_dev->dev,
            "can't autoresume for authorization: %d\n", result);
        goto error_autoresume;
    }
    result = usb_get_device_descriptor(usb_dev, sizeof(usb_dev->descriptor));
    if (result < 0) {
        dev_err(&usb_dev->dev, "can't re-read device descriptor for "
            "authorization: %d\n", result);
        goto error_device_descriptor;
    }

    kfree(usb_dev->product);
    usb_dev->product = NULL;
    kfree(usb_dev->manufacturer);
    usb_dev->manufacturer = NULL;
    kfree(usb_dev->serial);
    usb_dev->serial = NULL;

    usb_dev->authorized = 1;
    result = usb_enumerate_device(usb_dev);
    if (result < 0)
        goto error_enumerate;
    /* Choose and set the configuration.  This registers the interfaces
     * with the driver core and lets interface drivers bind to them.
     */
    c = usb_choose_configuration(usb_dev);
    if (c >= 0) {
        result = usb_set_configuration(usb_dev, c);
        if (result) {
            dev_err(&usb_dev->dev,
                "can't set config #%d, error %d\n", c, result);
            /* This need not be fatal.  The user can try to
             * set other configurations. */
        }
    }
    dev_info(&usb_dev->dev, "authorized to connect\n");

error_enumerate:
error_device_descriptor:
    usb_autosuspend_device(usb_dev);
error_autoresume:
out_authorized:
    usb_unlock_device(usb_dev); // complements locktree
    return result;
}


/* 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 == (int)old_scheme_first)

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

static int hub_port_reset(struct usb_hub *hub, int port1,
            struct usb_device *udev, unsigned int delay, bool warm);

/* Is a USB 3.0 port in the Inactive or Complinance Mode state?
 * Port worm reset is required to recover
 */
static bool hub_port_warm_reset_required(struct usb_hub *hub, u16 portstatus)
{
    return hub_is_superspeed(hub->hdev) &&
        (((portstatus & USB_PORT_STAT_LINK_STATE) ==
          USB_SS_PORT_LS_SS_INACTIVE) ||
         ((portstatus & USB_PORT_STAT_LINK_STATE) ==
          USB_SS_PORT_LS_COMP_MOD)) ;
}

static int hub_port_wait_reset(struct usb_hub *hub, int port1,
            struct usb_device *udev, unsigned int delay, bool warm)
{
    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;

        /*
         * Some buggy devices require a warm reset to be issued even
         * when the port appears not to be connected.
         */
        if (!warm) {
            /*
             * Some buggy devices can cause an NEC host controller
             * to transition to the "Error" state after a hot port
             * reset.  This will show up as the port state in
             * "Inactive", and the port may also report a
             * disconnect.  Forcing a warm port reset seems to make
             * the device work.
             *
             * See https://bugzilla.kernel.org/show_bug.cgi?id=41752
             */
            if (hub_port_warm_reset_required(hub, portstatus)) {
                int ret;

                if ((portchange & USB_PORT_STAT_C_CONNECTION))
                    clear_port_feature(hub->hdev, port1,
                            USB_PORT_FEAT_C_CONNECTION);
                if (portchange & USB_PORT_STAT_C_LINK_STATE)
                    clear_port_feature(hub->hdev, port1,
                            USB_PORT_FEAT_C_PORT_LINK_STATE);
                if (portchange & USB_PORT_STAT_C_RESET)
                    clear_port_feature(hub->hdev, port1,
                            USB_PORT_FEAT_C_RESET);
                dev_dbg(hub->intfdev, "hot reset failed, warm reset port %d\n",
                        port1);
                ret = hub_port_reset(hub, port1,
                        udev, HUB_BH_RESET_TIME,
                        true);
                if ((portchange & USB_PORT_STAT_C_CONNECTION))
                    clear_port_feature(hub->hdev, port1,
                            USB_PORT_FEAT_C_CONNECTION);
                return ret;
            }
            /* Device went away? */
            if (!(portstatus & USB_PORT_STAT_CONNECTION))
                return -ENOTCONN;

            /* bomb out completely if the connection bounced */
            if ((portchange & USB_PORT_STAT_C_CONNECTION))
                return -ENOTCONN;

            /* 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_WIRELESS;
                else if (hub_is_superspeed(hub->hdev))
                    udev->speed = USB_SPEED_SUPER;
                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;
            }
        } else {
            if (portchange & USB_PORT_STAT_C_BH_RESET)
                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 %sreset yet, waiting %dms\n",
            port1, warm ? "warm " : "", delay);
    }

    return -EBUSY;
}

static void hub_port_finish_reset(struct usb_hub *hub, int port1,
            struct usb_device *udev, int *status, bool warm)
{
    switch (*status) {
    case 0:
        if (!warm) {
            struct usb_hcd *hcd;
            /* TRSTRCY = 10 ms; plus some extra */
            msleep(10 + 40);
            update_devnum(udev, 0);
            hcd = bus_to_hcd(udev->bus);
            if (hcd->driver->reset_device) {
                *status = hcd->driver->reset_device(hcd, udev);
                if (*status < 0) {
                    dev_err(&udev->dev, "Cannot reset "
                            "HCD device state\n");
                    break;
                }
            }
        }
        /* FALL THROUGH */
    case -ENOTCONN:
    case -ENODEV:
        clear_port_feature(hub->hdev,
                port1, USB_PORT_FEAT_C_RESET);
        /* FIXME need disconnect() for NOTATTACHED device */
        if (warm) {
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_BH_PORT_RESET);
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_PORT_LINK_STATE);
        } else {
            usb_set_device_state(udev, *status
                    ? USB_STATE_NOTATTACHED
                    : USB_STATE_DEFAULT);
        }
        break;
    }
}

/* Handle port reset and port warm(BH) reset (for USB3 protocol ports) */
static int hub_port_reset(struct usb_hub *hub, int port1,
            struct usb_device *udev, unsigned int delay, bool warm)
{
    int i, status;

    if (!warm) {
        /* Block EHCI CF initialization during the port reset.
         * Some companion controllers don't like it when they mix.
         */
        down_read(&ehci_cf_port_reset_rwsem);
    } else {
        if (!hub_is_superspeed(hub->hdev)) {
            dev_err(hub->intfdev, "only USB3 hub support "
                        "warm reset\n");
            return -EINVAL;
        }
    }

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

        /* return on disconnect or reset */
        if (status == 0 || status == -ENOTCONN || status == -ENODEV) {
            hub_port_finish_reset(hub, port1, udev, &status, warm);
            goto done;
        }

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

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

done:
    if (!warm)
        up_read(&ehci_cf_port_reset_rwsem);

    return status;
}

/* Check if a port is power on */
static int port_is_power_on(struct usb_hub *hub, unsigned portstatus)
{
    int ret = 0;

    if (hub_is_superspeed(hub->hdev)) {
        if (portstatus & USB_SS_PORT_STAT_POWER)
            ret = 1;
    } else {
        if (portstatus & USB_PORT_STAT_POWER)
            ret = 1;
    }

    return ret;
}

#ifdef  CONFIG_PM

/* Check if a port is suspended(USB2.0 port) or in U3 state(USB3.0 port) */
static int port_is_suspended(struct usb_hub *hub, unsigned portstatus)
{
    int ret = 0;

    if (hub_is_superspeed(hub->hdev)) {
        if ((portstatus & USB_PORT_STAT_LINK_STATE)
                == USB_SS_PORT_LS_U3)
            ret = 1;
    } else {
        if (portstatus & USB_PORT_STAT_SUSPEND)
            ret = 1;
    }

    return ret;
}

/* Determine whether the device on a port is ready for a normal resume,
 * is ready for a reset-resume, or should be disconnected.
 */
static int check_port_resume_type(struct usb_device *udev,
        struct usb_hub *hub, int port1,
        int status, unsigned portchange, unsigned portstatus)
{
    /* Is the device still present? */
    if (status || port_is_suspended(hub, portstatus) ||
            !port_is_power_on(hub, portstatus) ||
            !(portstatus & USB_PORT_STAT_CONNECTION)) {
        if (status >= 0)
            status = -ENODEV;
    }

    /* Can't do a normal resume if the port isn't enabled,
     * so try a reset-resume instead.
     */
    else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume) {
        if (udev->persist_enabled)
            udev->reset_resume = 1;
        else
            status = -ENODEV;
    }

    if (status) {
        dev_dbg(hub->intfdev,
                "port %d status %04x.%04x after resume, %d\n",
                port1, portchange, portstatus, status);
    } else if (udev->reset_resume) {

        /* Late port handoff can set status-change bits */
        if (portchange & USB_PORT_STAT_C_CONNECTION)
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_CONNECTION);
        if (portchange & USB_PORT_STAT_C_ENABLE)
            clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_ENABLE);
    }

    return status;
}

int usb_disable_ltm(struct usb_device *udev)
{
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);

    /* Check if the roothub and device supports LTM. */
    if (!usb_device_supports_ltm(hcd->self.root_hub) ||
            !usb_device_supports_ltm(udev))
        return 0;

    /* Clear Feature LTM Enable can only be sent if the device is
     * configured.
     */
    if (!udev->actconfig)
        return 0;

    return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
            USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE,
            USB_DEVICE_LTM_ENABLE, 0, NULL, 0,
            USB_CTRL_SET_TIMEOUT);
}
EXPORT_SYMBOL_GPL(usb_disable_ltm);

void usb_enable_ltm(struct usb_device *udev)
{
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);

    /* Check if the roothub and device supports LTM. */
    if (!usb_device_supports_ltm(hcd->self.root_hub) ||
            !usb_device_supports_ltm(udev))
        return;

    /* Set Feature LTM Enable can only be sent if the device is
     * configured.
     */
    if (!udev->actconfig)
        return;

    usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
            USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
            USB_DEVICE_LTM_ENABLE, 0, NULL, 0,
            USB_CTRL_SET_TIMEOUT);
}
EXPORT_SYMBOL_GPL(usb_enable_ltm);

#ifdef  CONFIG_USB_SUSPEND

/*
 * usb_port_suspend - suspend a usb device's upstream port
 * @udev: device that's no longer in active use, not a root hub
 * 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.
 *
 * 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.
 *
 * 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.
 *
 * 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.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
{
    struct usb_hub  *hub = hdev_to_hub(udev->parent);
    int     port1 = udev->portnum;
    int     status;

    /* 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) {
        if (!hub_is_superspeed(hub->hdev)) {
            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);
        } else {
            /* Assume there's only one function on the USB 3.0
             * device and enable remote wake for the first
             * interface. FIXME if the interface association
             * descriptor shows there's more than one function.
             */
            status = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                    USB_REQ_SET_FEATURE,
                    USB_RECIP_INTERFACE,
                    USB_INTRF_FUNC_SUSPEND,
                    USB_INTRF_FUNC_SUSPEND_RW |
                    USB_INTRF_FUNC_SUSPEND_LP,
                    NULL, 0,
                    USB_CTRL_SET_TIMEOUT);
        }
        if (status) {
            dev_dbg(&udev->dev, "won't remote wakeup, status %d\n",
                    status);
            /* bail if autosuspend is requested */
            if (PMSG_IS_AUTO(msg))
                return status;
        }
    }

    /* disable USB2 hardware LPM */
    if (udev->usb2_hw_lpm_enabled == 1)
        usb_set_usb2_hardware_lpm(udev, 0);

    if (usb_disable_ltm(udev)) {
        dev_err(&udev->dev, "%s Failed to disable LTM before suspend\n.",
                __func__);
        return -ENOMEM;
    }
    if (usb_unlocked_disable_lpm(udev)) {
        dev_err(&udev->dev, "%s Failed to disable LPM before suspend\n.",
                __func__);
        return -ENOMEM;
    }

    /* see 7.1.7.6 */
    if (hub_is_superspeed(hub->hdev))
        status = set_port_feature(hub->hdev,
                port1 | (USB_SS_PORT_LS_U3 << 3),
                USB_PORT_FEAT_LINK_STATE);
    else
        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" */
        if (udev->do_remote_wakeup)
            (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);

        /* Try to enable USB2 hardware LPM again */
        if (udev->usb2_hw_lpm_capable == 1)
            usb_set_usb2_hardware_lpm(udev, 1);

        /* Try to enable USB3 LTM and LPM again */
        usb_enable_ltm(udev);
        usb_unlocked_enable_lpm(udev);

        /* System sleep transitions should never fail */
        if (!PMSG_IS_AUTO(msg))
            status = 0;
    } else {
        /* device has up to 10 msec to fully suspend */
        dev_dbg(&udev->dev, "usb %ssuspend, wakeup %d\n",
                (PMSG_IS_AUTO(msg) ? "auto-" : ""),
                udev->do_remote_wakeup);
        usb_set_device_state(udev, USB_STATE_SUSPENDED);
        msleep(10);
    }
    usb_mark_last_busy(hub->hdev);
    return status;
}

/*
 * 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.  This routine kicks 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.
 *
 * If @udev->reset_resume is set then the device is reset before the
 * status check is done.
 */
static int finish_port_resume(struct usb_device *udev)
{
    int status = 0;
    u16 devstatus;

    /* caller owns the udev device lock */
    dev_dbg(&udev->dev, "%s\n",
        udev->reset_resume ? "finish reset-resume" : "finish resume");

    /* 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 not to reset a suspended port if the attached
     * device is enabled for remote wakeup.  Hence the reset
     * operation is carried out here, after the port has been
     * resumed.
     */
    if (udev->reset_resume)
 retry_reset_resume:
        status = usb_reset_and_verify_device(udev);

    /* 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.
     */
    if (status == 0) {
        devstatus = 0;
        status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);
        if (status >= 0)
            status = (status > 0 ? 0 : -ENODEV);

        /* If a normal resume failed, try doing a reset-resume */
        if (status && !udev->reset_resume && udev->persist_enabled) {
            dev_dbg(&udev->dev, "retry with reset-resume\n");
            udev->reset_resume = 1;
            goto retry_reset_resume;
        }
    }

    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)) {
            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;
    }
    return status;
}

/*
 * usb_port_resume - re-activate a suspended usb device's upstream port
 * @udev: device to re-activate, not a root hub
 * 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.
 *
 * If @udev->reset_resume is set then this routine won't check that the
 * port is still enabled.  Furthermore, finish_port_resume() above will
 * reset @udev.  The end result is that a broken power session can be
 * recovered and @udev will appear to persist across a loss of VBUS power.
 *
 * For example, if a host controller doesn't maintain VBUS suspend current
 * during a system sleep or is reset when the system wakes up, all the USB
 * power sessions below it will be broken.  This is especially troublesome
 * for mass-storage devices containing mounted filesystems, since the
 * device will appear to have disconnected and all the memory mappings
 * to it will be lost.  Using the USB_PERSIST facility, the device can be
 * made to appear as if it had not disconnected.
 *
 * This facility can be dangerous.  Although usb_reset_and_verify_device() makes
 * every effort to insure that the same device is present after the
 * reset as before, it cannot provide a 100% guarantee.  Furthermore it's
 * quite possible for a device to remain unaltered but its media to be
 * changed.  If the user replaces a flash memory card while the system is
 * asleep, he will have only himself to blame when the filesystem on the
 * new card is corrupted and the system crashes.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_resume(struct usb_device *udev, pm_message_t msg)
{
    struct usb_hub  *hub = hdev_to_hub(udev->parent);
    int     port1 = udev->portnum;
    int     status;
    u16     portchange, portstatus;

    /* Skip the initial Clear-Suspend step for a remote wakeup */
    status = hub_port_status(hub, port1, &portstatus, &portchange);
    if (status == 0 && !port_is_suspended(hub, portstatus))
        goto SuspendCleared;

    // 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 */
    if (hub_is_superspeed(hub->hdev))
        status = set_port_feature(hub->hdev,
                port1 | (USB_SS_PORT_LS_U0 << 3),
                USB_PORT_FEAT_LINK_STATE);
    else
        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 {
        /* drive resume for at least 20 msec */
        dev_dbg(&udev->dev, "usb %sresume\n",
                (PMSG_IS_AUTO(msg) ? "auto-" : ""));
        msleep(25);

        /* Virtual root hubs can trigger on GET_PORT_STATUS to
         * stop resume signaling.  Then finish the resume
         * sequence.
         */
        status = hub_port_status(hub, port1, &portstatus, &portchange);

        /* TRSMRCY = 10 msec */
        msleep(10);
    }

 SuspendCleared:
    if (status == 0) {
        if (hub_is_superspeed(hub->hdev)) {
            if (portchange & USB_PORT_STAT_C_LINK_STATE)
                clear_port_feature(hub->hdev, port1,
                    USB_PORT_FEAT_C_PORT_LINK_STATE);
        } else {
            if (portchange & USB_PORT_STAT_C_SUSPEND)
                clear_port_feature(hub->hdev, port1,
                        USB_PORT_FEAT_C_SUSPEND);
        }
    }

    clear_bit(port1, hub->busy_bits);

    status = check_port_resume_type(udev,
            hub, port1, status, portchange, portstatus);
    if (status == 0)
        status = finish_port_resume(udev);
    if (status < 0) {
        dev_dbg(&udev->dev, "can't resume, status %d\n", status);
        hub_port_logical_disconnect(hub, port1);
    } else  {
        /* Try to enable USB2 hardware LPM */
        if (udev->usb2_hw_lpm_capable == 1)
            usb_set_usb2_hardware_lpm(udev, 1);

        /* Try to enable USB3 LTM and LPM */
        usb_enable_ltm(udev);
        usb_unlocked_enable_lpm(udev);
    }

    return status;
}

/* caller has locked udev */
int usb_remote_wakeup(struct usb_device *udev)
{
    int status = 0;

    if (udev->state == USB_STATE_SUSPENDED) {
        dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
        status = usb_autoresume_device(udev);
        if (status == 0) {
            /* Let the drivers do their thing, then... */
            usb_autosuspend_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, pm_message_t msg)
{
    return 0;
}

/* However we may need to do a reset-resume */

int usb_port_resume(struct usb_device *udev, pm_message_t msg)
{
    struct usb_hub  *hub = hdev_to_hub(udev->parent);
    int     port1 = udev->portnum;
    int     status;
    u16     portchange, portstatus;

    status = hub_port_status(hub, port1, &portstatus, &portchange);
    status = check_port_resume_type(udev,
            hub, port1, status, portchange, portstatus);

    if (status) {
        dev_dbg(&udev->dev, "can't resume, status %d\n", status);
        hub_port_logical_disconnect(hub, port1);
    } else if (udev->reset_resume) {
        dev_dbg(&udev->dev, "reset-resume\n");
        status = usb_reset_and_verify_device(udev);
    }
    return status;
}

#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;
    int         status;

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

        udev = hub->ports[port1 - 1]->child;
        if (udev && udev->can_submit) {
            dev_warn(&intf->dev, "port %d nyet suspended\n", port1);
            if (PMSG_IS_AUTO(msg))
                return -EBUSY;
        }
    }
    if (hub_is_superspeed(hdev) && hdev->do_remote_wakeup) {
        /* Enable hub to send remote wakeup for all ports. */
        for (port1 = 1; port1 <= hdev->maxchild; port1++) {
            status = set_port_feature(hdev,
                    port1 |
                    USB_PORT_FEAT_REMOTE_WAKE_CONNECT |
                    USB_PORT_FEAT_REMOTE_WAKE_DISCONNECT |
                    USB_PORT_FEAT_REMOTE_WAKE_OVER_CURRENT,
                    USB_PORT_FEAT_REMOTE_WAKE_MASK);
        }
    }

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

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

static int hub_resume(struct usb_interface *intf)
{
    struct usb_hub *hub = usb_get_intfdata(intf);

    dev_dbg(&intf->dev, "%s\n", __func__);
    hub_activate(hub, HUB_RESUME);
    return 0;
}

static int hub_reset_resume(struct usb_interface *intf)
{
    struct usb_hub *hub = usb_get_intfdata(intf);

    dev_dbg(&intf->dev, "%s\n", __func__);
    hub_activate(hub, HUB_RESET_RESUME);
    return 0;
}

void usb_root_hub_lost_power(struct usb_device *rhdev)
{
    dev_warn(&rhdev->dev, "root hub lost power or was reset\n");
    rhdev->reset_resume = 1;
}
EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);

static const char * const usb3_lpm_names[]  = {
    "U0",
    "U1",
    "U2",
    "U3",
};

/*
 * Send a Set SEL control transfer to the device, prior to enabling
 * device-initiated U1 or U2.  This lets the device know the exit latencies from
 * the time the device initiates a U1 or U2 exit, to the time it will receive a
 * packet from the host.
 *
 * This function will fail if the SEL or PEL values for udev are greater than
 * the maximum allowed values for the link state to be enabled.
 */
static int usb_req_set_sel(struct usb_device *udev, enum usb3_link_state state)
{
    struct usb_set_sel_req *sel_values;
    unsigned long long u1_sel;
    unsigned long long u1_pel;
    unsigned long long u2_sel;
    unsigned long long u2_pel;
    int ret;

    /* Convert SEL and PEL stored in ns to us */
    u1_sel = DIV_ROUND_UP(udev->u1_params.sel, 1000);
    u1_pel = DIV_ROUND_UP(udev->u1_params.pel, 1000);
    u2_sel = DIV_ROUND_UP(udev->u2_params.sel, 1000);
    u2_pel = DIV_ROUND_UP(udev->u2_params.pel, 1000);

    /*
     * Make sure that the calculated SEL and PEL values for the link
     * state we're enabling aren't bigger than the max SEL/PEL
     * value that will fit in the SET SEL control transfer.
     * Otherwise the device would get an incorrect idea of the exit
     * latency for the link state, and could start a device-initiated
     * U1/U2 when the exit latencies are too high.
     */
    if ((state == USB3_LPM_U1 &&
                (u1_sel > USB3_LPM_MAX_U1_SEL_PEL ||
                 u1_pel > USB3_LPM_MAX_U1_SEL_PEL)) ||
            (state == USB3_LPM_U2 &&
             (u2_sel > USB3_LPM_MAX_U2_SEL_PEL ||
              u2_pel > USB3_LPM_MAX_U2_SEL_PEL))) {
        dev_dbg(&udev->dev, "Device-initiated %s disabled due to long SEL %llu us or PEL %llu us\n",
                usb3_lpm_names[state], u1_sel, u1_pel);
        return -EINVAL;
    }

    /*
     * If we're enabling device-initiated LPM for one link state,
     * but the other link state has a too high SEL or PEL value,
     * just set those values to the max in the Set SEL request.
     */
    if (u1_sel > USB3_LPM_MAX_U1_SEL_PEL)
        u1_sel = USB3_LPM_MAX_U1_SEL_PEL;

    if (u1_pel > USB3_LPM_MAX_U1_SEL_PEL)
        u1_pel = USB3_LPM_MAX_U1_SEL_PEL;

    if (u2_sel > USB3_LPM_MAX_U2_SEL_PEL)
        u2_sel = USB3_LPM_MAX_U2_SEL_PEL;

    if (u2_pel > USB3_LPM_MAX_U2_SEL_PEL)
        u2_pel = USB3_LPM_MAX_U2_SEL_PEL;

    /*
     * usb_enable_lpm() can be called as part of a failed device reset,
     * which may be initiated by an error path of a mass storage driver.
     * Therefore, use GFP_NOIO.
     */
    sel_values = kmalloc(sizeof *(sel_values), GFP_NOIO);
    if (!sel_values)
        return -ENOMEM;

    sel_values->u1_sel = u1_sel;
    sel_values->u1_pel = u1_pel;
    sel_values->u2_sel = cpu_to_le16(u2_sel);
    sel_values->u2_pel = cpu_to_le16(u2_pel);

    ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
            USB_REQ_SET_SEL,
            USB_RECIP_DEVICE,
            0, 0,
            sel_values, sizeof *(sel_values),
            USB_CTRL_SET_TIMEOUT);
    kfree(sel_values);
    return ret;
}

/*
 * Enable or disable device-initiated U1 or U2 transitions.
 */
static int usb_set_device_initiated_lpm(struct usb_device *udev,
        enum usb3_link_state state, bool enable)
{
    int ret;
    int feature;

    switch (state) {
    case USB3_LPM_U1:
        feature = USB_DEVICE_U1_ENABLE;
        break;
    case USB3_LPM_U2:
        feature = USB_DEVICE_U2_ENABLE;
        break;
    default:
        dev_warn(&udev->dev, "%s: Can't %s non-U1 or U2 state.\n",
                __func__, enable ? "enable" : "disable");
        return -EINVAL;
    }

    if (udev->state != USB_STATE_CONFIGURED) {
        dev_dbg(&udev->dev, "%s: Can't %s %s state "
                "for unconfigured device.\n",
                __func__, enable ? "enable" : "disable",
                usb3_lpm_names[state]);
        return 0;
    }

    if (enable) {
        /*
         * Now send the control transfer to enable device-initiated LPM
         * for either U1 or U2.
         */
        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                USB_REQ_SET_FEATURE,
                USB_RECIP_DEVICE,
                feature,
                0, NULL, 0,
                USB_CTRL_SET_TIMEOUT);
    } else {
        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                USB_REQ_CLEAR_FEATURE,
                USB_RECIP_DEVICE,
                feature,
                0, NULL, 0,
                USB_CTRL_SET_TIMEOUT);
    }
    if (ret < 0) {
        dev_warn(&udev->dev, "%s of device-initiated %s failed.\n",
                enable ? "Enable" : "Disable",
                usb3_lpm_names[state]);
        return -EBUSY;
    }
    return 0;
}

static int usb_set_lpm_timeout(struct usb_device *udev,
        enum usb3_link_state state, int timeout)
{
    int ret;
    int feature;

    switch (state) {
    case USB3_LPM_U1:
        feature = USB_PORT_FEAT_U1_TIMEOUT;
        break;
    case USB3_LPM_U2:
        feature = USB_PORT_FEAT_U2_TIMEOUT;
        break;
    default:
        dev_warn(&udev->dev, "%s: Can't set timeout for non-U1 or U2 state.\n",
                __func__);
        return -EINVAL;
    }

    if (state == USB3_LPM_U1 && timeout > USB3_LPM_U1_MAX_TIMEOUT &&
            timeout != USB3_LPM_DEVICE_INITIATED) {
        dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x, "
                "which is a reserved value.\n",
                usb3_lpm_names[state], timeout);
        return -EINVAL;
    }

    ret = set_port_feature(udev->parent,
            USB_PORT_LPM_TIMEOUT(timeout) | udev->portnum,
            feature);
    if (ret < 0) {
        dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x,"
                "error code %i\n", usb3_lpm_names[state],
                timeout, ret);
        return -EBUSY;
    }
    if (state == USB3_LPM_U1)
        udev->u1_params.timeout = timeout;
    else
        udev->u2_params.timeout = timeout;
    return 0;
}

/*
 * Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
 * U1/U2 entry.
 *
 * We will attempt to enable U1 or U2, but there are no guarantees that the
 * control transfers to set the hub timeout or enable device-initiated U1/U2
 * will be successful.
 *
 * If we cannot set the parent hub U1/U2 timeout, we attempt to let the xHCI
 * driver know about it.  If that call fails, it should be harmless, and just
 * take up more slightly more bus bandwidth for unnecessary U1/U2 exit latency.
 */
static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
        enum usb3_link_state state)
{
    int timeout, ret;
    __u8 u1_mel = udev->bos->ss_cap->bU1devExitLat;
    __le16 u2_mel = udev->bos->ss_cap->bU2DevExitLat;

    /* If the device says it doesn't have *any* exit latency to come out of
     * U1 or U2, it's probably lying.  Assume it doesn't implement that link
     * state.
     */
    if ((state == USB3_LPM_U1 && u1_mel == 0) ||
            (state == USB3_LPM_U2 && u2_mel == 0))
        return;

    /*
     * First, let the device know about the exit latencies
     * associated with the link state we're about to enable.
     */
    ret = usb_req_set_sel(udev, state);
    if (ret < 0) {
        dev_warn(&udev->dev, "Set SEL for device-initiated %s failed.\n",
                usb3_lpm_names[state]);
        return;
    }

    /* We allow the host controller to set the U1/U2 timeout internally
     * first, so that it can change its schedule to account for the
     * additional latency to send data to a device in a lower power
     * link state.
     */
    timeout = hcd->driver->enable_usb3_lpm_timeout(hcd, udev, state);

    /* xHCI host controller doesn't want to enable this LPM state. */
    if (timeout == 0)
        return;

    if (timeout < 0) {
        dev_warn(&udev->dev, "Could not enable %s link state, "
                "xHCI error %i.\n", usb3_lpm_names[state],
                timeout);
        return;
    }

    if (usb_set_lpm_timeout(udev, state, timeout))
        /* If we can't set the parent hub U1/U2 timeout,
         * device-initiated LPM won't be allowed either, so let the xHCI
         * host know that this link state won't be enabled.
         */
        hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);

    /* Only a configured device will accept the Set Feature U1/U2_ENABLE */
    else if (udev->actconfig)
        usb_set_device_initiated_lpm(udev, state, true);

}

/*
 * Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
 * U1/U2 entry.
 *
 * If this function returns -EBUSY, the parent hub will still allow U1/U2 entry.
 * If zero is returned, the parent will not allow the link to go into U1/U2.
 *
 * If zero is returned, device-initiated U1/U2 entry may still be enabled, but
 * it won't have an effect on the bus link state because the parent hub will
 * still disallow device-initiated U1/U2 entry.
 *
 * If zero is returned, the xHCI host controller may still think U1/U2 entry is
 * possible.  The result will be slightly more bus bandwidth will be taken up
 * (to account for U1/U2 exit latency), but it should be harmless.
 */
static int usb_disable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
        enum usb3_link_state state)
{
    int feature;

    switch (state) {
    case USB3_LPM_U1:
        feature = USB_PORT_FEAT_U1_TIMEOUT;
        break;
    case USB3_LPM_U2:
        feature = USB_PORT_FEAT_U2_TIMEOUT;
        break;
    default:
        dev_warn(&udev->dev, "%s: Can't disable non-U1 or U2 state.\n",
                __func__);
        return -EINVAL;
    }

    if (usb_set_lpm_timeout(udev, state, 0))
        return -EBUSY;

    usb_set_device_initiated_lpm(udev, state, false);

    if (hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state))
        dev_warn(&udev->dev, "Could not disable xHCI %s timeout, "
                "bus schedule bandwidth may be impacted.\n",
                usb3_lpm_names[state]);
    return 0;
}

/*
 * Disable hub-initiated and device-initiated U1 and U2 entry.
 * Caller must own the bandwidth_mutex.
 *
 * This will call usb_enable_lpm() on failure, which will decrement
 * lpm_disable_count, and will re-enable LPM if lpm_disable_count reaches zero.
 */
int usb_disable_lpm(struct usb_device *udev)
{
    struct usb_hcd *hcd;

    if (!udev || !udev->parent ||
            udev->speed != USB_SPEED_SUPER ||
            !udev->lpm_capable)
        return 0;

    hcd = bus_to_hcd(udev->bus);
    if (!hcd || !hcd->driver->disable_usb3_lpm_timeout)
        return 0;

    udev->lpm_disable_count++;
    if ((udev->u1_params.timeout == 0 && udev->u2_params.timeout == 0))
        return 0;

    /* If LPM is enabled, attempt to disable it. */
    if (usb_disable_link_state(hcd, udev, USB3_LPM_U1))
        goto enable_lpm;
    if (usb_disable_link_state(hcd, udev, USB3_LPM_U2))
        goto enable_lpm;

    return 0;

enable_lpm:
    usb_enable_lpm(udev);
    return -EBUSY;
}
EXPORT_SYMBOL_GPL(usb_disable_lpm);

/* Grab the bandwidth_mutex before calling usb_disable_lpm() */
int usb_unlocked_disable_lpm(struct usb_device *udev)
{
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);
    int ret;

    if (!hcd)
        return -EINVAL;

    mutex_lock(hcd->bandwidth_mutex);
    ret = usb_disable_lpm(udev);
    mutex_unlock(hcd->bandwidth_mutex);

    return ret;
}
EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);

/*
 * Attempt to enable device-initiated and hub-initiated U1 and U2 entry.  The
 * xHCI host policy may prevent U1 or U2 from being enabled.
 *
 * Other callers may have disabled link PM, so U1 and U2 entry will be disabled
 * until the lpm_disable_count drops to zero.  Caller must own the
 * bandwidth_mutex.
 */
void usb_enable_lpm(struct usb_device *udev)
{
    struct usb_hcd *hcd;

    if (!udev || !udev->parent ||
            udev->speed != USB_SPEED_SUPER ||
            !udev->lpm_capable)
        return;

    udev->lpm_disable_count--;
    hcd = bus_to_hcd(udev->bus);
    /* Double check that we can both enable and disable LPM.
     * Device must be configured to accept set feature U1/U2 timeout.
     */
    if (!hcd || !hcd->driver->enable_usb3_lpm_timeout ||
            !hcd->driver->disable_usb3_lpm_timeout)
        return;

    if (udev->lpm_disable_count > 0)
        return;

    usb_enable_link_state(hcd, udev, USB3_LPM_U1);
    usb_enable_link_state(hcd, udev, USB3_LPM_U2);
}
EXPORT_SYMBOL_GPL(usb_enable_lpm);

/* Grab the bandwidth_mutex before calling usb_enable_lpm() */
void usb_unlocked_enable_lpm(struct usb_device *udev)
{
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);

    if (!hcd)
        return;

    mutex_lock(hcd->bandwidth_mutex);
    usb_enable_lpm(udev);
    mutex_unlock(hcd->bandwidth_mutex);
}
EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm);


#else   /* CONFIG_PM */

#define hub_suspend     NULL
#define hub_resume      NULL
#define hub_reset_resume    NULL

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

void usb_enable_lpm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_enable_lpm);

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

void usb_unlocked_enable_lpm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm);

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

void usb_enable_ltm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_enable_ltm);
#endif


/* 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.
 */
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;
}

void usb_ep0_reinit(struct usb_device *udev)
{
    usb_disable_endpoint(udev, 0 + USB_DIR_IN, true);
    usb_disable_endpoint(udev, 0 + USB_DIR_OUT, true);
    usb_enable_endpoint(udev, &udev->ep0, true);
}
EXPORT_SYMBOL_GPL(usb_ep0_reinit);

#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 devnum)
{
    int retval;
    struct usb_hcd *hcd = bus_to_hcd(udev->bus);

    /*
     * The host controller will choose the device address,
     * instead of the core having chosen it earlier
     */
    if (!hcd->driver->address_device && devnum <= 1)
        return -EINVAL;
    if (udev->state == USB_STATE_ADDRESS)
        return 0;
    if (udev->state != USB_STATE_DEFAULT)
        return -EINVAL;
    if (hcd->driver->address_device)
        retval = hcd->driver->address_device(hcd, udev);
    else
        retval = usb_control_msg(udev, usb_sndaddr0pipe(),
                USB_REQ_SET_ADDRESS, 0, devnum, 0,
                NULL, 0, USB_CTRL_SET_TIMEOUT);
    if (retval == 0) {
        update_devnum(udev, devnum);
        /* Device now using proper address. */
        usb_set_device_state(udev, USB_STATE_ADDRESS);
        usb_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_and_verify_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;
    struct usb_hcd      *hcd = bus_to_hcd(hdev->bus);
    int         i, j, retval;
    unsigned        delay = HUB_SHORT_RESET_TIME;
    enum usb_device_speed   oldspeed = udev->speed;
    const char      *speed;
    int         devnum = udev->devnum;

    /* 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 */
    /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
    retval = hub_port_reset(hub, port1, udev, delay, false);
    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_SUPER:
    case USB_SPEED_WIRELESS:    /* fixed at 512 */
        udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512);
        break;
    case USB_SPEED_HIGH:        /* fixed at 64 */
        udev->ep0.desc.wMaxPacketSize = 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 = cpu_to_le16(64);
        break;
    case USB_SPEED_LOW:     /* fixed at 8 */
        udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8);
        break;
    default:
        goto fail;
    }

    if (udev->speed == USB_SPEED_WIRELESS)
        speed = "variable speed Wireless";
    else
        speed = usb_speed_string(udev->speed);

    if (udev->speed != USB_SPEED_SUPER)
        dev_info(&udev->dev,
                "%s %s USB device number %d using %s\n",
                (udev->config) ? "reset" : "new", speed,
                devnum, udev->bus->controller->driver->name);

    /* 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) {
        if (!hub->tt.hub) {
            dev_err(&udev->dev, "parent hub has no TT\n");
            retval = -EINVAL;
            goto fail;
        }
        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) && !(hcd->driver->flags & HCD_USB3)) {
            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;
            }

            /* 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,
                    initial_descriptor_timeout);
                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, false);
            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/64, error %d\n",
                    r);
                retval = -EMSGSIZE;
                continue;
            }
#undef GET_DESCRIPTOR_BUFSIZE
        }

        /*
         * If device is WUSB, we already assigned an
         * unauthorized address in the Connect Ack sequence;
         * authorization will assign the final address.
         */
        if (udev->wusb == 0) {
            for (j = 0; j < SET_ADDRESS_TRIES; ++j) {
                retval = hub_set_address(udev, devnum);
                if (retval >= 0)
                    break;
                msleep(200);
            }
            if (retval < 0) {
                dev_err(&udev->dev,
                    "device not accepting address %d, error %d\n",
                    devnum, retval);
                goto fail;
            }
            if (udev->speed == USB_SPEED_SUPER) {
                devnum = udev->devnum;
                dev_info(&udev->dev,
                        "%s SuperSpeed USB device number %d using %s\n",
                        (udev->config) ? "reset" : "new",
                        devnum, udev->bus->controller->driver->name);
            }

            /* 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) && !(hcd->driver->flags & HCD_USB3))
                break;
        }

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

    /*
     * Some superspeed devices have finished the link training process
     * and attached to a superspeed hub port, but the device descriptor
     * got from those devices show they aren't superspeed devices. Warm
     * reset the port attached by the devices can fix them.
     */
    if ((udev->speed == USB_SPEED_SUPER) &&
            (le16_to_cpu(udev->descriptor.bcdUSB) < 0x0300)) {
        dev_err(&udev->dev, "got a wrong device descriptor, "
                "warm reset device\n");
        hub_port_reset(hub, port1, udev,
                HUB_BH_RESET_TIME, true);
        retval = -EINVAL;
        goto fail;
    }

    if (udev->descriptor.bMaxPacketSize0 == 0xff ||
            udev->speed == USB_SPEED_SUPER)
        i = 512;
    else
        i = udev->descriptor.bMaxPacketSize0;
    if (usb_endpoint_maxp(&udev->ep0.desc) != i) {
        if (udev->speed == USB_SPEED_LOW ||
                !(i == 8 || i == 16 || i == 32 || i == 64)) {
            dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", i);
            retval = -EMSGSIZE;
            goto fail;
        }
        if (udev->speed == USB_SPEED_FULL)
            dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
        else
            dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
        udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
        usb_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/all, error %d\n",
            retval);
        if (retval >= 0)
            retval = -ENOMSG;
        goto fail;
    }

    if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
        retval = usb_get_bos_descriptor(udev);
        if (!retval) {
            udev->lpm_capable = usb_device_supports_lpm(udev);
            usb_set_lpm_parameters(udev);
        }
    }

    retval = 0;
    /* notify HCD that we have a device connected and addressed */
    if (hcd->driver->update_device)
        hcd->driver->update_device(hcd, udev);
fail:
    if (retval) {
        hub_port_disable(hub, port1, 0);
        update_devnum(udev, devnum);    /* for disconnect processing */
    }
    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, GFP_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_delayed_work (&hub->leds, 0);
        }
    }
    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 = hub->ports[port1 - 1]->child;
        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_and_verify_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;
    struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
    unsigned wHubCharacteristics =
            le16_to_cpu(hub->descriptor->wHubCharacteristics);
    struct usb_device *udev;
    int status, i;

    dev_dbg (hub_dev,
        "port %d, status %04x, change %04x, %s\n",
        port1, portstatus, portchange, portspeed(hub, portstatus));

    if (hub->has_indicators) {
        set_port_led(hub, port1, HUB_LED_AUTO);
        hub->indicator[port1-1] = INDICATOR_AUTO;
    }

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

    /* Try to resuscitate an existing device */
    udev = hub->ports[port1 - 1]->child;
    if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
            udev->state != USB_STATE_NOTATTACHED) {
        usb_lock_device(udev);
        if (portstatus & USB_PORT_STAT_ENABLE) {
            status = 0;     /* Nothing to do */

#ifdef CONFIG_USB_SUSPEND
        } else if (udev->state == USB_STATE_SUSPENDED &&
                udev->persist_enabled) {
            /* For a suspended device, treat this as a
             * remote wakeup event.
             */
            status = usb_remote_wakeup(udev);
#endif

        } else {
            status = -ENODEV;   /* Don't resuscitate */
        }
        usb_unlock_device(udev);

        if (status == 0) {
            clear_bit(port1, hub->change_bits);
            return;
        }
    }

    /* Disconnect any existing devices under this port */
    if (udev)
        usb_disconnect(&hub->ports[port1 - 1]->child);
    clear_bit(port1, hub->change_bits);

    /* We can forget about a "removed" device when there's a physical
     * disconnect or the connect status changes.
     */
    if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
            (portchange & USB_PORT_STAT_C_CONNECTION))
        clear_bit(port1, hub->removed_bits);

    if (portchange & (USB_PORT_STAT_C_CONNECTION |
                USB_PORT_STAT_C_ENABLE)) {
        status = hub_port_debounce(hub, port1);
        if (status < 0) {
            if (printk_ratelimit())
                dev_err(hub_dev, "connect-debounce failed, "
                        "port %d disabled\n", port1);
            portstatus &= ~USB_PORT_STAT_CONNECTION;
        } else {
            portstatus = status;
        }
    }

    if (hcd->phy && !hdev->parent) {
        if (portstatus & USB_PORT_STAT_CONNECTION)
            usb_phy_notify_connect(hcd->phy, port1);
        else
            usb_phy_notify_disconnect(hcd->phy, port1);
    }

    /* Return now if debouncing failed or nothing is connected or
     * the device was "removed".
     */
    if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
            test_bit(port1, hub->removed_bits)) {

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

        if (portstatus & USB_PORT_STAT_ENABLE)
            goto done;
        return;
    }

    for (i = 0; i < SET_CONFIG_TRIES; i++) {

        /* 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->bus_mA = hub->mA_per_port;
        udev->level = hdev->level + 1;
        udev->wusb = hub_is_wusb(hub);

        /* Only USB 3.0 devices are connected to SuperSpeed hubs. */
        if (hub_is_superspeed(hub->hdev))
            udev->speed = USB_SPEED_SUPER;
        else
            udev->speed = USB_SPEED_UNKNOWN;

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

        /* reset (non-USB 3.0 devices) and get descriptor */
        status = hub_port_init(hub, udev, port1, i);
        if (status < 0)
            goto loop;

        usb_detect_quirks(udev);
        if (udev->quirks & USB_QUIRK_DELAY_INIT)
            msleep(1000);

        /* 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_delayed_work (&hub->leds, 0);
                }
                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
            hub->ports[port1 - 1]->child = 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);
                hub->ports[port1 - 1]->child = 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:
        usb_ep0_reinit(udev);
        release_devnum(udev);
        hub_free_dev(udev);
        usb_put_dev(udev);
        if ((status == -ENOTCONN) || (status == -ENOTSUPP))
            break;
    }
    if (hub->hdev->parent ||
            !hcd->driver->port_handed_over ||
            !(hcd->driver->port_handed_over)(hcd, port1))
        dev_err(hub_dev, "unable to enumerate USB device on port %d\n",
                port1);
 
done:
    hub_port_disable(hub, port1, 1);
    if (hcd->driver->relinquish_port && !hub->hdev->parent)
        hcd->driver->relinquish_port(hcd, port1);
}

/* Returns 1 if there was a remote wakeup and a connect status change. */
static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
        u16 portstatus, u16 portchange)
{
    struct usb_device *hdev;
    struct usb_device *udev;
    int connect_change = 0;
    int ret;

    hdev = hub->hdev;
    udev = hub->ports[port - 1]->child;
    if (!hub_is_superspeed(hdev)) {
        if (!(portchange & USB_PORT_STAT_C_SUSPEND))
            return 0;
        clear_port_feature(hdev, port, USB_PORT_FEAT_C_SUSPEND);
    } else {
        if (!udev || udev->state != USB_STATE_SUSPENDED ||
                 (portstatus & USB_PORT_STAT_LINK_STATE) !=
                 USB_SS_PORT_LS_U0)
            return 0;
    }

    if (udev) {
        /* TRSMRCY = 10 msec */
        msleep(10);

        usb_lock_device(udev);
        ret = usb_remote_wakeup(udev);
        usb_unlock_device(udev);
        if (ret < 0)
            connect_change = 1;
    } else {
        ret = -ENODEV;
        hub_port_disable(hub, port, 1);
    }
    dev_dbg(hub->intfdev, "resume on port %d, status %d\n",
            port, ret);
    return connect_change;
}

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, wakeup_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);
        kref_get(&hub->kref);
        spin_unlock_irq(&hub_event_lock);

        hdev = hub->hdev;
        hub_dev = hub->intfdev;
        intf = to_usb_interface(hub_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]);

        /* Lock the device, then check to see if we were
         * disconnected while waiting for the lock to succeed. */
        usb_lock_device(hdev);
        if (unlikely(hub->disconnected))
            goto loop_disconnected;

        /* If the hub has died, clean up after it */
        if (hdev->state == USB_STATE_NOTATTACHED) {
            hub->error = -ENODEV;
            hub_quiesce(hub, HUB_DISCONNECT);
            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_device(hdev);
            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);
            wakeup_change = test_and_clear_bit(i, hub->wakeup_bits);
            if (!test_and_clear_bit(i, hub->event_bits) &&
                    !connect_change && !wakeup_change)
                continue;

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

            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
                    && hub->ports[i - 1]->child) {
                    dev_err (hub_dev,
                        "port %i "
                        "disabled by hub (EMI?), "
                        "re-enabling...\n",
                        i);
                    connect_change = 1;
                }
            }

            if (hub_handle_remote_wakeup(hub, i,
                        portstatus, portchange))
                connect_change = 1;

            if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                u16 status = 0;
                u16 unused;

                dev_dbg(hub_dev, "over-current change on port "
                    "%d\n", i);
                clear_port_feature(hdev, i,
                    USB_PORT_FEAT_C_OVER_CURRENT);
                msleep(100);    /* Cool down */
                hub_power_on(hub, true);
                hub_port_status(hub, i, &status, &unused);
                if (status & USB_PORT_STAT_OVERCURRENT)
                    dev_err(hub_dev, "over-current "
                        "condition on port %d\n", i);
            }

            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 ((portchange & USB_PORT_STAT_C_BH_RESET) &&
                    hub_is_superspeed(hub->hdev)) {
                dev_dbg(hub_dev,
                    "warm reset change on port %d\n",
                    i);
                clear_port_feature(hdev, i,
                    USB_PORT_FEAT_C_BH_PORT_RESET);
            }
            if (portchange & USB_PORT_STAT_C_LINK_STATE) {
                clear_port_feature(hub->hdev, i,
                        USB_PORT_FEAT_C_PORT_LINK_STATE);
            }
            if (portchange & USB_PORT_STAT_C_CONFIG_ERROR) {
                dev_warn(hub_dev,
                    "config error on port %d\n",
                    i);
                clear_port_feature(hub->hdev, i,
                        USB_PORT_FEAT_C_PORT_CONFIG_ERROR);
            }

            /* Warm reset a USB3 protocol port if it's in
             * SS.Inactive state.
             */
            if (hub_port_warm_reset_required(hub, portstatus)) {
                dev_dbg(hub_dev, "warm reset port %d\n", i);
                hub_port_reset(hub, i, NULL,
                        HUB_BH_RESET_TIME, true);
            }

            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 = 1;
                else
                    hub->limited_power = 0;
            }
            if (hubchange & HUB_CHANGE_OVERCURRENT) {
                u16 status = 0;
                u16 unused;

                dev_dbg(hub_dev, "over-current change\n");
                clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
                msleep(500);    /* Cool down */
                            hub_power_on(hub, true);
                hub_hub_status(hub, &status, &unused);
                if (status & HUB_STATUS_OVERCURRENT)
                    dev_err(hub_dev, "over-current "
                        "condition\n");
            }
        }

 loop_autopm:
        /* Balance the usb_autopm_get_interface() above */
        usb_autopm_put_interface_no_suspend(intf);
 loop:
        /* Balance the usb_autopm_get_interface_no_resume() in
         * kick_khubd() and allow autosuspend.
         */
        usb_autopm_put_interface(intf);
 loop_disconnected:
        usb_unlock_device(hdev);
        kref_put(&hub->kref, hub_release);

        } /* end while (1) */
}

static int hub_thread(void *__unused)
{
    /* khubd needs to be freezable to avoid intefering with USB-PERSIST
     * port handover.  Otherwise it might see that a full-speed device
     * was gone before the EHCI controller had handed its port over to
     * the companion full-speed controller.
     */
    set_freezable();

    do {
        hub_events();
        wait_event_freezable(khubd_wait,
                !list_empty(&hub_event_list) ||
                kthread_should_stop());
    } while (!kthread_should_stop() || !list_empty(&hub_event_list));

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

static const 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,
    .reset_resume = hub_reset_resume,
    .pre_reset =    hub_pre_reset,
    .post_reset =   hub_post_reset,
    .unlocked_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 descriptors_changed(struct usb_device *udev,
        struct usb_device_descriptor *old_device_descriptor)
{
    int     changed = 0;
    unsigned    index;
    unsigned    serial_len = 0;
    unsigned    len;
    unsigned    old_length;
    int     length;
    char        *buf;

    if (memcmp(&udev->descriptor, old_device_descriptor,
            sizeof(*old_device_descriptor)) != 0)
        return 1;

    /* Since the idVendor, idProduct, and bcdDevice values in the
     * device descriptor haven't changed, we will assume the
     * Manufacturer and Product strings haven't changed either.
     * But the SerialNumber string could be different (e.g., a
     * different flash card of the same brand).
     */
    if (udev->serial)
        serial_len = strlen(udev->serial) + 1;

    len = serial_len;
    for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
        old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
        len = max(len, old_length);
    }

    buf = kmalloc(len, GFP_NOIO);
    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++) {
        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);
            changed = 1;
            break;
        }
        if (memcmp (buf, udev->rawdescriptors[index], old_length)
                != 0) {
            dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
                index,
                ((struct usb_config_descriptor *) buf)->
                    bConfigurationValue);
            changed = 1;
            break;
        }
    }

    if (!changed && serial_len) {
        length = usb_string(udev, udev->descriptor.iSerialNumber,
                buf, serial_len);
        if (length + 1 != serial_len) {
            dev_dbg(&udev->dev, "serial string error %d\n",
                    length);
            changed = 1;
        } else if (memcmp(buf, udev->serial, length) != 0) {
            dev_dbg(&udev->dev, "serial string changed\n");
            changed = 1;
        }
    }

    kfree(buf);
    return changed;
}

static int usb_reset_and_verify_device(struct usb_device *udev)
{
    struct usb_device       *parent_hdev = udev->parent;
    struct usb_hub          *parent_hub;
    struct usb_hcd          *hcd = bus_to_hcd(udev->bus);
    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_restart() */
        dev_dbg(&udev->dev, "%s for root hub!\n", __func__);
        return -EISDIR;
    }
    parent_hub = hdev_to_hub(parent_hdev);

    /* Disable LPM and LTM while we reset the device and reinstall the alt
     * settings.  Device-initiated LPM settings, and system exit latency
     * settings are cleared when the device is reset, so we have to set
     * them up again.
     */
    ret = usb_unlocked_disable_lpm(udev);
    if (ret) {
        dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
        goto re_enumerate;
    }
    ret = usb_disable_ltm(udev);
    if (ret) {
        dev_err(&udev->dev, "%s Failed to disable LTM\n.",
                __func__);
        goto re_enumerate;
    }

    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. */
        usb_ep0_reinit(udev);
        ret = hub_port_init(parent_hub, udev, port1, i);
        if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV)
            break;
    }
    clear_bit(port1, parent_hub->busy_bits);

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

    /* Restore the device's previous configuration */
    if (!udev->actconfig)
        goto done;

    mutex_lock(hcd->bandwidth_mutex);
    ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL);
    if (ret < 0) {
        dev_warn(&udev->dev,
                "Busted HC?  Not enough HCD resources for "
                "old configuration.\n");
        mutex_unlock(hcd->bandwidth_mutex);
        goto re_enumerate;
    }
    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);
        mutex_unlock(hcd->bandwidth_mutex);
        goto re_enumerate;
    }
    mutex_unlock(hcd->bandwidth_mutex);
    usb_set_device_state(udev, USB_STATE_CONFIGURED);

    /* Put interfaces back into the same altsettings as before.
     * Don't bother to send the Set-Interface request for interfaces
     * that were already in altsetting 0; besides being unnecessary,
     * many devices can't handle it.  Instead just reset the host-side
     * endpoint state.
     */
    for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
        struct usb_host_config *config = udev->actconfig;
        struct usb_interface *intf = config->interface[i];
        struct usb_interface_descriptor *desc;

        desc = &intf->cur_altsetting->desc;
        if (desc->bAlternateSetting == 0) {
            usb_disable_interface(udev, intf, true);
            usb_enable_interface(udev, intf, true);
            ret = 0;
        } else {
            /* Let the bandwidth allocation function know that this
             * device has been reset, and it will have to use
             * alternate setting 0 as the current alternate setting.
             */
            intf->resetting_device = 1;
            ret = usb_set_interface(udev, desc->bInterfaceNumber,
                    desc->bAlternateSetting);
            intf->resetting_device = 0;
        }
        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:
    /* Now that the alt settings are re-installed, enable LTM and LPM. */
    usb_unlocked_enable_lpm(udev);
    usb_enable_ltm(udev);
    return 0;
 
re_enumerate:
    /* LPM state doesn't matter when we're about to destroy the device. */
    hub_port_logical_disconnect(parent_hub, port1);
    return -ENODEV;
}

int usb_reset_device(struct usb_device *udev)
{
    int ret;
    int i;
    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);

    if (config) {
        for (i = 0; i < config->desc.bNumInterfaces; ++i) {
            struct usb_interface *cintf = config->interface[i];
            struct usb_driver *drv;
            int unbind = 0;

            if (cintf->dev.driver) {
                drv = to_usb_driver(cintf->dev.driver);
                if (drv->pre_reset && drv->post_reset)
                    unbind = (drv->pre_reset)(cintf);
                else if (cintf->condition ==
                        USB_INTERFACE_BOUND)
                    unbind = 1;
                if (unbind)
                    usb_forced_unbind_intf(cintf);
            }
        }
    }

    ret = usb_reset_and_verify_device(udev);

    if (config) {
        for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
            struct usb_interface *cintf = config->interface[i];
            struct usb_driver *drv;
            int rebind = cintf->needs_binding;

            if (!rebind && cintf->dev.driver) {
                drv = to_usb_driver(cintf->dev.driver);
                if (drv->post_reset)
                    rebind = (drv->post_reset)(cintf);
                else if (cintf->condition ==
                        USB_INTERFACE_BOUND)
                    rebind = 1;
            }
            if (ret == 0 && rebind)
                usb_rebind_intf(cintf);
        }
    }

    usb_autosuspend_device(udev);
    return ret;
}
EXPORT_SYMBOL_GPL(usb_reset_device);


void usb_queue_reset_device(struct usb_interface *iface)
{
    schedule_work(&iface->reset_ws);
}
EXPORT_SYMBOL_GPL(usb_queue_reset_device);

struct usb_device *usb_hub_find_child(struct usb_device *hdev,
        int port1)
{
    struct usb_hub *hub = hdev_to_hub(hdev);

    if (port1 < 1 || port1 > hdev->maxchild)
        return NULL;
    return hub->ports[port1 - 1]->child;
}
EXPORT_SYMBOL_GPL(usb_hub_find_child);

void usb_set_hub_port_connect_type(struct usb_device *hdev, int port1,
    enum usb_port_connect_type type)
{
    struct usb_hub *hub = hdev_to_hub(hdev);

    hub->ports[port1 - 1]->connect_type = type;
}

enum usb_port_connect_type
usb_get_hub_port_connect_type(struct usb_device *hdev, int port1)
{
    struct usb_hub *hub = hdev_to_hub(hdev);

    return hub->ports[port1 - 1]->connect_type;
}

#ifdef CONFIG_ACPI

acpi_handle usb_get_hub_port_acpi_handle(struct usb_device *hdev,
    int port1)
{
    struct usb_hub *hub = hdev_to_hub(hdev);

    return DEVICE_ACPI_HANDLE(&hub->ports[port1 - 1]->dev);
}
#endif