USB: Fix USB3.0 Port Speed Downgrade after port reset

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

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

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/usb/hcd.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/pm_runtime.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_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 */
#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;
        void                    **port_owners;
};


/* 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 int 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 int old_scheme_first = 0;
module_param(old_scheme_first, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(old_scheme_first,
                 "start with the old device initialization scheme");

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

/* 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


static int usb_reset_and_verify_device(struct usb_device *udev);

static inline char *portspeed(int portstatus)
{
        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 if (portstatus & USB_PORT_STAT_SUPER_SPEED)
                return "5.0 Gb/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)
                return NULL;
        return usb_get_intfdata(hdev->actconfig->interface[0]);
}

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

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

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

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

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

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

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

static void led_work (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; i++) {
                status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_HUB, 0, 0,
                        data, sizeof(*data), USB_STS_TIMEOUT);
        }
        return status;
}

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

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

static 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);
}


/* 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 (--limit && !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;

                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);
}

/**
 * usb_hub_clear_tt_buffer - clear control/bulk TT state in high speed hub
 * @urb: an URB associated with the failed or incomplete split transaction
 *
 * High speed HCDs use this to tell the hub driver that some split control or
 * bulk transaction failed in a way that requires clearing internal state of
 * a transaction translator.  This is normally detected (and reported) from
 * interrupt context.
 *
 * It may not be possible for that hub to handle additional full (or low)
 * speed transactions until that state is fully cleared out.
 */
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 (hdev->children[port1-1] && set_state)
                usb_set_device_state(hdev->children[port1-1],
                                USB_STATE_NOTATTACHED);
        if (!hub->error)
                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 connnect-change event, so that some
 * time later khubd will disconnect() any existing usb_device on the port
 * and will re-enumerate if there actually is a device attached.
 */
static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
{
        dev_dbg(hub->intfdev, "logical disconnect on port %d\n", port1);
        hub_port_disable(hub, port1, 1);

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

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

/**
 * usb_remove_device - disable a device's port on its parent hub
 * @udev: device to be disabled and removed
 * Context: @udev locked, must be able to sleep.
 *
 * After @udev's port has been disabled, khubd is notified and it will
 * see that the device has been disconnected.  When the device is
 * physically unplugged and something is plugged in, the events will
 * be received and processed normally.
 */
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;
        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;

        /* After a resume, port power should still be on.
         * For any other type of activation, turn it on.
         */
        if (type != HUB_RESUME) {

                /* 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 {
                        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 = hdev->children[port1-1];
                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.
                         * FIXME: USB3 root hub and external hubs are treated
                         * differently here.
                         */
                        if (hdev->descriptor.bDeviceProtocol != 3 ||
                            (!hdev->parent &&
                             !(portstatus & USB_PORT_STAT_SUPER_SPEED))) {
                                clear_port_feature(hdev, port1,
                                                   USB_PORT_FEAT_ENABLE);
                                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);
                }

                /* 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) {
                        /* 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.
                         */
                        if (portchange)
                                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 (hdev->children[i])
                                usb_disconnect(&hdev->children[i]);
                }
        }

        /* Stop khubd and related activity */
        usb_kill_urb(hub->urb);
        if (hub->has_indicators)
                cancel_delayed_work_sync(&hub->leds);
        if (hub->tt.hub)
                cancel_work_sync(&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 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;
        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,
                        sizeof(*hub->descriptor));
        if (ret < 0) {
                message = "can't read hub descriptor";
                goto fail;
        } else if (hub->descriptor->bNbrPorts > USB_MAXCHILDREN) {
                message = "hub has too many ports!";
                ret = -ENODEV;
                goto fail;
        }

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

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

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

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

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

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

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

        spin_lock_init (&hub->tt.lock);
        INIT_LIST_HEAD (&hub->tt.clear_list);
        INIT_WORK(&hub->tt.clear_work, hub_tt_work);
        switch (hdev->descriptor.bDeviceProtocol) {
                case 0:
                        break;
                case 1:
                        dev_dbg(hub_dev, "Single TT\n");
                        hub->tt.hub = hdev;
                        break;
                case 2:
                        ret = usb_set_interface(hdev, 0, 1);
                        if (ret == 0) {
                                dev_dbg(hub_dev, "TT per port\n");
                                hub->tt.multi = 1;
                        } else
                                dev_err(hub_dev, "Using single TT (err %d)\n",
                                        ret);
                        hub->tt.hub = hdev;
                        break;
                case 3:
                        /* 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;

        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);

        /* 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);
        hub->hdev->maxchild = 0;

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

        usb_free_urb(hub->urb);
        kfree(hub->port_owners);
        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);

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

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

                return info->nports + 1;
                }

        default:
                return -ENOSYS;
        }
}

/*
 * 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,
                void ***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)->port_owners[port1 - 1]);
        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, void *owner)
{
        int rc;
        void **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, void *owner)
{
        int rc;
        void **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, void *owner)
{
        int n;
        void **powner;

        n = find_port_owner(hdev, 1, &powner);
        if (n == 0) {
                for (; n < hdev->maxchild; (++n, ++powner)) {
                        if (*powner == owner)
                                *powner = 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->port_owners[udev->portnum - 1];
}


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

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

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

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

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

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

static void update_address(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);
}

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

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

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

        usb_lock_device(udev);

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

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

/**
 * usb_enumerate_device_otg - FIXME (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * Finish enumeration for On-The-Go devices
 */
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;
}


/**
 * usb_enumerate_device - Read device configs/intfs/otg (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is only called by usb_new_device() and usb_authorize_device()
 * and FIXME -- all comments that apply to them apply here wrt to
 * environment.
 *
 * If the device is WUSB and not authorized, we don't attempt to read
 * the string descriptors, as they will be errored out by the device
 * until it has been authorized.
 */
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);
                        goto fail;
                }
        }
        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);
fail:
        return err;
}


/**
 * usb_new_device - perform initial device setup (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is called with devices which have been detected but not fully
 * enumerated.  The device descriptor is available, but not descriptors
 * for any device configuration.  The caller must have locked either
 * the parent hub (if udev is a normal device) or else the
 * usb_bus_list_lock (if udev is a root hub).  The parent's pointer to
 * udev has already been installed, but udev is not yet visible through
 * sysfs or other filesystem code.
 *
 * It will return if the device is configured properly or not.  Zero if
 * the interface was registered with the driver core; else a negative
 * errno value.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Only the hub driver or root-hub registrar should ever call this.
 */
int usb_new_device(struct usb_device *udev)
{
        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_enable(&udev->dev);

        usb_detect_quirks(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);

        device_enable_async_suspend(&udev->dev);
        /* 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);
        return err;

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


/**
 * usb_deauthorize_device - deauthorize a device (usbcore-internal)
 * @usb_dev: USB device
 *
 * Move the USB device to a very basic state where interfaces are disabled
 * and the device is in fact unconfigured and unusable.
 *
 * We share a lock (that we have) with device_del(), so we need to
 * defer its call.
 */
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 == old_scheme_first)

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

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

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

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

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

                /* bomb out completely if 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 (portstatus & USB_PORT_STAT_SUPER_SPEED)
                                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;
                }

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

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

        return -EBUSY;
}

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

        hcd = bus_to_hcd(udev->bus);
        /* 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);

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

                /* return on disconnect or reset */
                switch (status) {
                case 0:
                        /* TRSTRCY = 10 ms; plus some extra */
                        msleep(10 + 40);
                        update_address(udev, 0);
                        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 */
                        usb_set_device_state(udev, status
                                        ? USB_STATE_NOTATTACHED
                                        : USB_STATE_DEFAULT);
                        goto done;
                }

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

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

 done:
        up_read(&ehci_cf_port_reset_rwsem);
        return status;
}

#ifdef  CONFIG_PM

#define MASK_BITS       (USB_PORT_STAT_POWER | USB_PORT_STAT_CONNECTION | \
                                USB_PORT_STAT_SUSPEND)
#define WANT_BITS       (USB_PORT_STAT_POWER | USB_PORT_STAT_CONNECTION)

/* 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 || (portstatus & MASK_BITS) != WANT_BITS) {
                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;
}

#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;

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

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

        /* see 7.1.7.6 */
        status = set_port_feature(hub->hdev, port1, USB_PORT_FEAT_SUSPEND);
        if (status) {
                dev_dbg(hub->intfdev, "can't suspend port %d, status %d\n",
                                port1, status);
                /* paranoia:  "should not happen" */
                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);
        } else {
                /* device has up to 10 msec to fully suspend */
                dev_dbg(&udev->dev, "usb %ssuspend\n",
                                (msg.event & PM_EVENT_AUTO ? "auto-" : ""));
                usb_set_device_state(udev, USB_STATE_SUSPENDED);
                msleep(10);
        }
        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 && !(portstatus & USB_PORT_STAT_SUSPEND))
                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 */
        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",
                                (msg.event & PM_EVENT_AUTO ? "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 (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);
        }
        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;

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

                udev = hdev->children [port1-1];
                if (udev && udev->can_submit) {
                        if (!(msg.event & PM_EVENT_AUTO))
                                dev_dbg(&intf->dev, "port %d nyet suspended\n",
                                                port1);
                        return -EBUSY;
                }
        }

        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;
}

/**
 * usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
 * @rhdev: struct usb_device for the root hub
 *
 * The USB host controller driver calls this function when its root hub
 * is resumed and Vbus power has been interrupted or the controller
 * has been reset.  The routine marks @rhdev as having lost power.
 * When the hub driver is resumed it will take notice and carry out
 * power-session recovery for all the "USB-PERSIST"-enabled child devices;
 * the others will be disconnected.
 */
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);

#else   /* CONFIG_PM */

#define hub_suspend             NULL
#define hub_resume              NULL
#define hub_reset_resume        NULL
#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_address(udev, devnum);
        }
        if (retval == 0) {
                /* 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;
        char                    *speed, *type;
        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);

        if (!udev->config && oldspeed == USB_SPEED_SUPER) {
                /* Don't reset USB 3.0 devices during an initial setup */
                usb_set_device_state(udev, USB_STATE_DEFAULT);
        } else {
                /* 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);
                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;
        }
 
        type = "";
        switch (udev->speed) {
        case USB_SPEED_LOW:     speed = "low";  break;
        case USB_SPEED_FULL:    speed = "full"; break;
        case USB_SPEED_HIGH:    speed = "high"; break;
        case USB_SPEED_SUPER:
                                speed = "super";
                                break;
        case USB_SPEED_WIRELESS:
                                speed = "variable";
                                type = "Wireless ";
                                break;
        default:                speed = "?";    break;
        }
        if (udev->speed != USB_SPEED_SUPER)
                dev_info(&udev->dev,
                                "%s %s speed %sUSB device using %s and address %d\n",
                                (udev->config) ? "reset" : "new", speed, type,
                                udev->bus->controller->driver->name, devnum);

        /* Set up TT records, if needed  */
        if (hdev->tt) {
                udev->tt = hdev->tt;
                udev->ttport = hdev->ttport;
        } else if (udev->speed != USB_SPEED_HIGH
                        && hdev->speed == USB_SPEED_HIGH) {
                udev->tt = &hub->tt;
                udev->ttport = port1;
        }
 
        /* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
         * Because device hardware and firmware is sometimes buggy in
         * this area, and this is how Linux has done it for ages.
         * Change it cautiously.
         *
         * NOTE:  If USE_NEW_SCHEME() is true we will start by issuing
         * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
         * so it may help with some non-standards-compliant devices.
         * Otherwise we start with SET_ADDRESS and then try to read the
         * first 8 bytes of the device descriptor to get the ep0 maxpacket
         * value.
         */
        for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
                /*
                 * An xHCI controller cannot send any packets to a device until
                 * a set address command successfully completes.
                 */
                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);
                        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 using %s and address %d\n",
                                                (udev->config) ? "reset" : "new",
                                                udev->bus->controller->driver->name, devnum);
                        }

                        /* 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;

        if (udev->descriptor.bMaxPacketSize0 == 0xff ||
                        udev->speed == USB_SPEED_SUPER)
                i = 512;
        else
                i = udev->descriptor.bMaxPacketSize0;
        if (le16_to_cpu(udev->ep0.desc.wMaxPacketSize) != i) {
                if (udev->speed != USB_SPEED_FULL ||
                                !(i == 8 || i == 16 || i == 32 || i == 64)) {
                        dev_err(&udev->dev, "ep0 maxpacket = %d\n", i);
                        retval = -EMSGSIZE;
                        goto fail;
                }
                dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
                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;
        }

        retval = 0;

fail:
        if (retval) {
                hub_port_disable(hub, port1, 0);
                update_address(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 = hdev->children[port1 - 1];
                int                     delta;

                if (!udev)
                        continue;

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

/* Handle physical or logical connection change events.
 * This routine is called when:
 *      a port connection-change occurs;
 *      a port enable-change occurs (often caused by EMI);
 *      usb_reset_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 (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 = hdev->children[port1-1];
        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(&hdev->children[port1-1]);
        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;
                }
        }

        /* 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
                                && !(portstatus & USB_PORT_STAT_POWER))
                        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);

                /*
                 * USB 3.0 devices are reset automatically before the connect
                 * port status change appears, and the root hub port status
                 * shows the correct speed.  We also get port change
                 * notifications for USB 3.0 devices from the USB 3.0 portion of
                 * an external USB 3.0 hub, but this isn't handled correctly yet
                 * FIXME.
                 */

                if (!(hcd->driver->flags & HCD_USB3))
                        udev->speed = USB_SPEED_UNKNOWN;
                else if ((hdev->parent == NULL) &&
                                (portstatus & USB_PORT_STAT_SUPER_SPEED))
                        udev->speed = USB_SPEED_SUPER;
                else
                        udev->speed = USB_SPEED_UNKNOWN;

                /*
                 * xHCI needs to issue an address device command later
                 * in the hub_port_init sequence for SS/HS/FS/LS devices.
                 */
                if (!(hcd->driver->flags & HCD_USB3)) {
                        /* set the address */
                        choose_address(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;

                /* 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
                        hdev->children[port1-1] = udev;
                spin_unlock_irq(&device_state_lock);

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

                if (status)
                        goto loop_disable;

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

                return;

loop_disable:
                hub_port_disable(hub, port1, 1);
loop:
                usb_ep0_reinit(udev);
                release_address(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);
}

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

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

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

                tmp = hub_event_list.next;
                list_del_init(tmp);

                hub = list_entry(tmp, struct usb_hub, event_list);
                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);
                        if (!test_and_clear_bit(i, hub->event_bits) &&
                                        !connect_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
                                    && hdev->children[i-1]) {
                                        dev_err (hub_dev,
                                            "port %i "
                                            "disabled by hub (EMI?), "
                                            "re-enabling...\n",
                                                i);
                                        connect_change = 1;
                                }
                        }

                        if (portchange & USB_PORT_STAT_C_SUSPEND) {
                                struct usb_device *udev;

                                clear_port_feature(hdev, i,
                                        USB_PORT_FEAT_C_SUSPEND);
                                udev = hdev->children[i-1];
                                if (udev) {
                                        /* TRSMRCY = 10 msec */
                                        msleep(10);

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

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

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

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

 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,
        .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;
}

/**
 * usb_reset_and_verify_device - perform a USB port reset to reinitialize a device
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * WARNING - don't use this routine to reset a composite device
 * (one with multiple interfaces owned by separate drivers)!
 * Use usb_reset_device() instead.
 *
 * Do a port reset, reassign the device's address, and establish its
 * former operating configuration.  If the reset fails, or the device's
 * descriptors change from their values before the reset, or the original
 * configuration and altsettings cannot be restored, a flag will be set
 * telling khubd to pretend the device has been disconnected and then
 * re-connected.  All drivers will be unbound, and the device will be
 * re-enumerated and probed all over again.
 *
 * Returns 0 if the reset succeeded, -ENODEV if the device has been
 * flagged for logical disconnection, or some other negative error code
 * if the reset wasn't even attempted.
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 *
 * Locking exception: This routine may also be called from within an
 * autoresume handler.  Such usage won't conflict with other tasks
 * holding the device lock because these tasks should always call
 * usb_autopm_resume_device(), thereby preventing any unwanted autoresume.
 */
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 hc_restart() */
                dev_dbg(&udev->dev, "%s for root hub!\n", __func__);
                return -EISDIR;
        }
        parent_hub = hdev_to_hub(parent_hdev);

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

                /* ep0 maxpacket size may change; let the HCD know about it.
                 * Other endpoints will be handled by re-enumeration. */
                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:
        return 0;
 
re_enumerate:
        hub_port_logical_disconnect(parent_hub, port1);
        return -ENODEV;
}

/**
 * usb_reset_device - warn interface drivers and perform a USB port reset
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * Warns all drivers bound to registered interfaces (using their pre_reset
 * method), performs the port reset, and then lets the drivers know that
 * the reset is over (using their post_reset method).
 *
 * Return value is the same as for usb_reset_and_verify_device().
 *
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 *
 * If an interface is currently being probed or disconnected, we assume
 * its driver knows how to handle resets.  For all other interfaces,
 * if the driver doesn't have pre_reset and post_reset methods then
 * we attempt to unbind it and rebind afterward.
 */
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);


/**
 * usb_queue_reset_device - Reset a USB device from an atomic context
 * @iface: USB interface belonging to the device to reset
 *
 * This function can be used to reset a USB device from an atomic
 * context, where usb_reset_device() won't work (as it blocks).
 *
 * Doing a reset via this method is functionally equivalent to calling
 * usb_reset_device(), except for the fact that it is delayed to a
 * workqueue. This means that any drivers bound to other interfaces
 * might be unbound, as well as users from usbfs in user space.
 *
 * Corner cases:
 *
 * - Scheduling two resets at the same time from two different drivers
 *   attached to two different interfaces of the same device is
 *   possible; depending on how the driver attached to each interface
 *   handles ->pre_reset(), the second reset might happen or not.
 *
 * - If a driver is unbound and it had a pending reset, the reset will
 *   be cancelled.
 *
 * - This function can be called during .probe() or .disconnect()
 *   times. On return from .disconnect(), any pending resets will be
 *   cancelled.
 *
 * There is no no need to lock/unlock the @reset_ws as schedule_work()
 * does its own.
 *
 * NOTE: We don't do any reference count tracking because it is not
 *     needed. The lifecycle of the work_struct is tied to the
 *     usb_interface. Before destroying the interface we cancel the
 *     work_struct, so the fact that work_struct is queued and or
 *     running means the interface (and thus, the device) exist and
 *     are referenced.
 */
void usb_queue_reset_device(struct usb_interface *iface)
{
        schedule_work(&iface->reset_ws);
}
EXPORT_SYMBOL_GPL(usb_queue_reset_device);