vhci_hcd.c

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/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "usbip_common.h"
#include "vhci.h"

#define DRIVER_AUTHOR "Takahiro Hirofuchi"
#define DRIVER_DESC "USB/IP 'Virtual' Host Controller (VHCI) Driver"

/*
 * TODO
 *  - update root hub emulation
 *  - move the emulation code to userland ?
 *      porting to other operating systems
 *      minimize kernel code
 *  - add suspend/resume code
 *  - clean up everything
 */

/* See usb gadget dummy hcd */

static int vhci_hub_status(struct usb_hcd *hcd, char *buff);
static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
                u16 wIndex, char *buff, u16 wLength);
static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
                gfp_t mem_flags);
static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status);
static int vhci_start(struct usb_hcd *vhci_hcd);
static void vhci_stop(struct usb_hcd *hcd);
static int vhci_get_frame_number(struct usb_hcd *hcd);

static const char driver_name[] = "vhci_hcd";
static const char driver_desc[] = "USB/IP Virtual Host Controller";

struct vhci_hcd *the_controller;

static const char * const bit_desc[] = {
    "CONNECTION",       /*0*/
    "ENABLE",       /*1*/
    "SUSPEND",      /*2*/
    "OVER_CURRENT",     /*3*/
    "RESET",        /*4*/
    "R5",           /*5*/
    "R6",           /*6*/
    "R7",           /*7*/
    "POWER",        /*8*/
    "LOWSPEED",     /*9*/
    "HIGHSPEED",        /*10*/
    "PORT_TEST",        /*11*/
    "INDICATOR",        /*12*/
    "R13",          /*13*/
    "R14",          /*14*/
    "R15",          /*15*/
    "C_CONNECTION",     /*16*/
    "C_ENABLE",     /*17*/
    "C_SUSPEND",        /*18*/
    "C_OVER_CURRENT",   /*19*/
    "C_RESET",      /*20*/
    "R21",          /*21*/
    "R22",          /*22*/
    "R23",          /*23*/
    "R24",          /*24*/
    "R25",          /*25*/
    "R26",          /*26*/
    "R27",          /*27*/
    "R28",          /*28*/
    "R29",          /*29*/
    "R30",          /*30*/
    "R31",          /*31*/
};

static void dump_port_status_diff(u32 prev_status, u32 new_status)
{
    int i = 0;
    u32 bit = 1;

    pr_debug("status prev -> new: %08x -> %08x\n", prev_status, new_status);
    while (bit) {
        u32 prev = prev_status & bit;
        u32 new = new_status & bit;
        char change;

        if (!prev && new)
            change = '+';
        else if (prev && !new)
            change = '-';
        else
            change = ' ';

        if (prev || new)
            pr_debug(" %c%s\n", change, bit_desc[i]);
        bit <<= 1;
        i++;
    }
    pr_debug("\n");
}

void rh_port_connect(int rhport, enum usb_device_speed speed)
{
    unsigned long   flags;

    usbip_dbg_vhci_rh("rh_port_connect %d\n", rhport);

    spin_lock_irqsave(&the_controller->lock, flags);

    the_controller->port_status[rhport] |= USB_PORT_STAT_CONNECTION
        | (1 << USB_PORT_FEAT_C_CONNECTION);

    switch (speed) {
    case USB_SPEED_HIGH:
        the_controller->port_status[rhport] |= USB_PORT_STAT_HIGH_SPEED;
        break;
    case USB_SPEED_LOW:
        the_controller->port_status[rhport] |= USB_PORT_STAT_LOW_SPEED;
        break;
    default:
        break;
    }

    /* spin_lock(&the_controller->vdev[rhport].ud.lock);
     * the_controller->vdev[rhport].ud.status = VDEV_CONNECT;
     * spin_unlock(&the_controller->vdev[rhport].ud.lock); */

    spin_unlock_irqrestore(&the_controller->lock, flags);

    usb_hcd_poll_rh_status(vhci_to_hcd(the_controller));
}

void rh_port_disconnect(int rhport)
{
    unsigned long flags;

    usbip_dbg_vhci_rh("rh_port_disconnect %d\n", rhport);

    spin_lock_irqsave(&the_controller->lock, flags);
    /* stop_activity(dum, driver); */
    the_controller->port_status[rhport] &= ~USB_PORT_STAT_CONNECTION;
    the_controller->port_status[rhport] |=
                    (1 << USB_PORT_FEAT_C_CONNECTION);

    /* not yet complete the disconnection
     * spin_lock(&vdev->ud.lock);
     * vdev->ud.status = VHC_ST_DISCONNECT;
     * spin_unlock(&vdev->ud.lock); */

    spin_unlock_irqrestore(&the_controller->lock, flags);
    usb_hcd_poll_rh_status(vhci_to_hcd(the_controller));
}

#define PORT_C_MASK             \
    ((USB_PORT_STAT_C_CONNECTION        \
      | USB_PORT_STAT_C_ENABLE      \
      | USB_PORT_STAT_C_SUSPEND     \
      | USB_PORT_STAT_C_OVERCURRENT     \
      | USB_PORT_STAT_C_RESET) << 16)

/*
 * Returns 0 if the status hasn't changed, or the number of bytes in buf.
 * Ports are 0-indexed from the HCD point of view,
 * and 1-indexed from the USB core pointer of view.
 *
 * @buf: a bitmap to show which port status has been changed.
 *  bit  0: reserved
 *  bit  1: the status of port 0 has been changed.
 *  bit  2: the status of port 1 has been changed.
 *  ...
 */
static int vhci_hub_status(struct usb_hcd *hcd, char *buf)
{
    struct vhci_hcd *vhci;
    unsigned long   flags;
    int     retval;
    int     rhport;
    int     changed = 0;

    retval = DIV_ROUND_UP(VHCI_NPORTS + 1, 8);
    memset(buf, 0, retval);

    vhci = hcd_to_vhci(hcd);

    spin_lock_irqsave(&vhci->lock, flags);
    if (!HCD_HW_ACCESSIBLE(hcd)) {
        usbip_dbg_vhci_rh("hw accessible flag not on?\n");
        goto done;
    }

    /* check pseudo status register for each port */
    for (rhport = 0; rhport < VHCI_NPORTS; rhport++) {
        if ((vhci->port_status[rhport] & PORT_C_MASK)) {
            /* The status of a port has been changed, */
            usbip_dbg_vhci_rh("port %d status changed\n", rhport);

            buf[(rhport + 1) / 8] |= 1 << (rhport + 1) % 8;
            changed = 1;
        }
    }

    pr_info("changed %d\n", changed);

    if ((hcd->state == HC_STATE_SUSPENDED) && (changed == 1))
        usb_hcd_resume_root_hub(hcd);

done:
    spin_unlock_irqrestore(&vhci->lock, flags);
    return changed ? retval : 0;
}

/* See hub_configure in hub.c */
static inline void hub_descriptor(struct usb_hub_descriptor *desc)
{
    memset(desc, 0, sizeof(*desc));
    desc->bDescriptorType = 0x29;
    desc->bDescLength = 9;
    desc->wHubCharacteristics = (__force __u16)
        (__constant_cpu_to_le16(0x0001));
    desc->bNbrPorts = VHCI_NPORTS;
    desc->u.hs.DeviceRemovable[0] = 0xff;
    desc->u.hs.DeviceRemovable[1] = 0xff;
}

static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
                u16 wIndex, char *buf, u16 wLength)
{
    struct vhci_hcd *dum;
    int             retval = 0;
    unsigned long   flags;
    int     rhport;

    u32 prev_port_status[VHCI_NPORTS];

    if (!HCD_HW_ACCESSIBLE(hcd))
        return -ETIMEDOUT;

    /*
     * NOTE:
     * wIndex shows the port number and begins from 1.
     */
    usbip_dbg_vhci_rh("typeReq %x wValue %x wIndex %x\n", typeReq, wValue,
              wIndex);
    if (wIndex > VHCI_NPORTS)
        pr_err("invalid port number %d\n", wIndex);
    rhport = ((__u8)(wIndex & 0x00ff)) - 1;

    dum = hcd_to_vhci(hcd);

    spin_lock_irqsave(&dum->lock, flags);

    /* store old status and compare now and old later */
    if (usbip_dbg_flag_vhci_rh) {
        memcpy(prev_port_status, dum->port_status,
            sizeof(prev_port_status));
    }

    switch (typeReq) {
    case ClearHubFeature:
        usbip_dbg_vhci_rh(" ClearHubFeature\n");
        break;
    case ClearPortFeature:
        switch (wValue) {
        case USB_PORT_FEAT_SUSPEND:
            if (dum->port_status[rhport] & USB_PORT_STAT_SUSPEND) {
                /* 20msec signaling */
                dum->resuming = 1;
                dum->re_timeout =
                    jiffies + msecs_to_jiffies(20);
            }
            break;
        case USB_PORT_FEAT_POWER:
            usbip_dbg_vhci_rh(" ClearPortFeature: "
                      "USB_PORT_FEAT_POWER\n");
            dum->port_status[rhport] = 0;
            /* dum->address = 0; */
            /* dum->hdev = 0; */
            dum->resuming = 0;
            break;
        case USB_PORT_FEAT_C_RESET:
            usbip_dbg_vhci_rh(" ClearPortFeature: "
                      "USB_PORT_FEAT_C_RESET\n");
            switch (dum->vdev[rhport].speed) {
            case USB_SPEED_HIGH:
                dum->port_status[rhport] |=
                    USB_PORT_STAT_HIGH_SPEED;
                break;
            case USB_SPEED_LOW:
                dum->port_status[rhport] |=
                    USB_PORT_STAT_LOW_SPEED;
                break;
            default:
                break;
            }
        default:
            usbip_dbg_vhci_rh(" ClearPortFeature: default %x\n",
                      wValue);
            dum->port_status[rhport] &= ~(1 << wValue);
            break;
        }
        break;
    case GetHubDescriptor:
        usbip_dbg_vhci_rh(" GetHubDescriptor\n");
        hub_descriptor((struct usb_hub_descriptor *) buf);
        break;
    case GetHubStatus:
        usbip_dbg_vhci_rh(" GetHubStatus\n");
        *(__le32 *) buf = __constant_cpu_to_le32(0);
        break;
    case GetPortStatus:
        usbip_dbg_vhci_rh(" GetPortStatus port %x\n", wIndex);
        if (wIndex > VHCI_NPORTS || wIndex < 1) {
            pr_err("invalid port number %d\n", wIndex);
            retval = -EPIPE;
        }

        /* we do no care of resume. */

        /* whoever resets or resumes must GetPortStatus to
         * complete it!!
         *                                   */
        if (dum->resuming && time_after(jiffies, dum->re_timeout)) {
            dum->port_status[rhport] |=
                (1 << USB_PORT_FEAT_C_SUSPEND);
            dum->port_status[rhport] &=
                ~(1 << USB_PORT_FEAT_SUSPEND);
            dum->resuming = 0;
            dum->re_timeout = 0;
            /* if (dum->driver && dum->driver->resume) {
             *  spin_unlock (&dum->lock);
             *  dum->driver->resume (&dum->gadget);
             *  spin_lock (&dum->lock);
             * } */
        }

        if ((dum->port_status[rhport] & (1 << USB_PORT_FEAT_RESET)) !=
            0 && time_after(jiffies, dum->re_timeout)) {
            dum->port_status[rhport] |=
                (1 << USB_PORT_FEAT_C_RESET);
            dum->port_status[rhport] &=
                ~(1 << USB_PORT_FEAT_RESET);
            dum->re_timeout = 0;

            if (dum->vdev[rhport].ud.status ==
                VDEV_ST_NOTASSIGNED) {
                usbip_dbg_vhci_rh(" enable rhport %d "
                          "(status %u)\n",
                          rhport,
                          dum->vdev[rhport].ud.status);
                dum->port_status[rhport] |=
                    USB_PORT_STAT_ENABLE;
            }
        }
        ((u16 *) buf)[0] = cpu_to_le16(dum->port_status[rhport]);
        ((u16 *) buf)[1] = cpu_to_le16(dum->port_status[rhport] >> 16);

        usbip_dbg_vhci_rh(" GetPortStatus bye %x %x\n", ((u16 *)buf)[0],
                  ((u16 *)buf)[1]);
        break;
    case SetHubFeature:
        usbip_dbg_vhci_rh(" SetHubFeature\n");
        retval = -EPIPE;
        break;
    case SetPortFeature:
        switch (wValue) {
        case USB_PORT_FEAT_SUSPEND:
            usbip_dbg_vhci_rh(" SetPortFeature: "
                      "USB_PORT_FEAT_SUSPEND\n");
            break;
        case USB_PORT_FEAT_RESET:
            usbip_dbg_vhci_rh(" SetPortFeature: "
                      "USB_PORT_FEAT_RESET\n");
            /* if it's already running, disconnect first */
            if (dum->port_status[rhport] & USB_PORT_STAT_ENABLE) {
                dum->port_status[rhport] &=
                    ~(USB_PORT_STAT_ENABLE |
                      USB_PORT_STAT_LOW_SPEED |
                      USB_PORT_STAT_HIGH_SPEED);
                /* FIXME test that code path! */
            }
            /* 50msec reset signaling */
            dum->re_timeout = jiffies + msecs_to_jiffies(50);

            /* FALLTHROUGH */
        default:
            usbip_dbg_vhci_rh(" SetPortFeature: default %d\n",
                      wValue);
            dum->port_status[rhport] |= (1 << wValue);
            break;
        }
        break;

    default:
        pr_err("default: no such request\n");
        /* dev_dbg (hardware,
         *      "hub control req%04x v%04x i%04x l%d\n",
         *      typeReq, wValue, wIndex, wLength); */

        /* "protocol stall" on error */
        retval = -EPIPE;
    }

    if (usbip_dbg_flag_vhci_rh) {
        pr_debug("port %d\n", rhport);
        /* Only dump valid port status */
        if (rhport >= 0) {
            dump_port_status_diff(prev_port_status[rhport],
                          dum->port_status[rhport]);
        }
    }
    usbip_dbg_vhci_rh(" bye\n");

    spin_unlock_irqrestore(&dum->lock, flags);

    return retval;
}

static struct vhci_device *get_vdev(struct usb_device *udev)
{
    int i;

    if (!udev)
        return NULL;

    for (i = 0; i < VHCI_NPORTS; i++)
        if (the_controller->vdev[i].udev == udev)
            return port_to_vdev(i);

    return NULL;
}

static void vhci_tx_urb(struct urb *urb)
{
    struct vhci_device *vdev = get_vdev(urb->dev);
    struct vhci_priv *priv;
    unsigned long flag;

    if (!vdev) {
        pr_err("could not get virtual device");
        /* BUG(); */
        return;
    }

    priv = kzalloc(sizeof(struct vhci_priv), GFP_ATOMIC);

    spin_lock_irqsave(&vdev->priv_lock, flag);

    if (!priv) {
        dev_err(&urb->dev->dev, "malloc vhci_priv\n");
        spin_unlock_irqrestore(&vdev->priv_lock, flag);
        usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
        return;
    }

    priv->seqnum = atomic_inc_return(&the_controller->seqnum);
    if (priv->seqnum == 0xffff)
        dev_info(&urb->dev->dev, "seqnum max\n");

    priv->vdev = vdev;
    priv->urb = urb;

    urb->hcpriv = (void *) priv;

    list_add_tail(&priv->list, &vdev->priv_tx);

    wake_up(&vdev->waitq_tx);
    spin_unlock_irqrestore(&vdev->priv_lock, flag);
}

static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
                gfp_t mem_flags)
{
    struct device *dev = &urb->dev->dev;
    int ret = 0;
    unsigned long flags;
    struct vhci_device *vdev;

    usbip_dbg_vhci_hc("enter, usb_hcd %p urb %p mem_flags %d\n",
              hcd, urb, mem_flags);

    /* patch to usb_sg_init() is in 2.5.60 */
    BUG_ON(!urb->transfer_buffer && urb->transfer_buffer_length);

    spin_lock_irqsave(&the_controller->lock, flags);

    if (urb->status != -EINPROGRESS) {
        dev_err(dev, "URB already unlinked!, status %d\n", urb->status);
        spin_unlock_irqrestore(&the_controller->lock, flags);
        return urb->status;
    }

    vdev = port_to_vdev(urb->dev->portnum-1);

    /* refuse enqueue for dead connection */
    spin_lock(&vdev->ud.lock);
    if (vdev->ud.status == VDEV_ST_NULL ||
        vdev->ud.status == VDEV_ST_ERROR) {
        dev_err(dev, "enqueue for inactive port %d\n", vdev->rhport);
        spin_unlock(&vdev->ud.lock);
        spin_unlock_irqrestore(&the_controller->lock, flags);
        return -ENODEV;
    }
    spin_unlock(&vdev->ud.lock);

    ret = usb_hcd_link_urb_to_ep(hcd, urb);
    if (ret)
        goto no_need_unlink;

    /*
     * The enumeration process is as follows;
     *
     *  1. Get_Descriptor request to DevAddrs(0) EndPoint(0)
     *     to get max packet length of default pipe
     *
     *  2. Set_Address request to DevAddr(0) EndPoint(0)
     *
     */
    if (usb_pipedevice(urb->pipe) == 0) {
        __u8 type = usb_pipetype(urb->pipe);
        struct usb_ctrlrequest *ctrlreq =
            (struct usb_ctrlrequest *) urb->setup_packet;

        if (type != PIPE_CONTROL || !ctrlreq) {
            dev_err(dev, "invalid request to devnum 0\n");
            ret = -EINVAL;
            goto no_need_xmit;
        }

        switch (ctrlreq->bRequest) {
        case USB_REQ_SET_ADDRESS:
            /* set_address may come when a device is reset */
            dev_info(dev, "SetAddress Request (%d) to port %d\n",
                 ctrlreq->wValue, vdev->rhport);

            if (vdev->udev)
                usb_put_dev(vdev->udev);
            vdev->udev = usb_get_dev(urb->dev);

            spin_lock(&vdev->ud.lock);
            vdev->ud.status = VDEV_ST_USED;
            spin_unlock(&vdev->ud.lock);

            if (urb->status == -EINPROGRESS) {
                /* This request is successfully completed. */
                /* If not -EINPROGRESS, possibly unlinked. */
                urb->status = 0;
            }

            goto no_need_xmit;

        case USB_REQ_GET_DESCRIPTOR:
            if (ctrlreq->wValue == (USB_DT_DEVICE << 8))
                usbip_dbg_vhci_hc("Not yet?: "
                          "Get_Descriptor to device 0 "
                          "(get max pipe size)\n");

            if (vdev->udev)
                usb_put_dev(vdev->udev);
            vdev->udev = usb_get_dev(urb->dev);
            goto out;

        default:
            /* NOT REACHED */
            dev_err(dev, "invalid request to devnum 0 bRequest %u, "
                "wValue %u\n", ctrlreq->bRequest,
                ctrlreq->wValue);
            ret =  -EINVAL;
            goto no_need_xmit;
        }

    }

out:
    vhci_tx_urb(urb);
    spin_unlock_irqrestore(&the_controller->lock, flags);

    return 0;

no_need_xmit:
    usb_hcd_unlink_urb_from_ep(hcd, urb);
no_need_unlink:
    spin_unlock_irqrestore(&the_controller->lock, flags);
    usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb, urb->status);
    return ret;
}

/*
 * vhci_rx gives back the urb after receiving the reply of the urb.  If an
 * unlink pdu is sent or not, vhci_rx receives a normal return pdu and gives
 * back its urb. For the driver unlinking the urb, the content of the urb is
 * not important, but the calling to its completion handler is important; the
 * completion of unlinking is notified by the completion handler.
 *
 *
 * CLIENT SIDE
 *
 * - When vhci_hcd receives RET_SUBMIT,
 *
 *  - case 1a). the urb of the pdu is not unlinking.
 *      - normal case
 *      => just give back the urb
 *
 *  - case 1b). the urb of the pdu is unlinking.
 *      - usbip.ko will return a reply of the unlinking request.
 *      => give back the urb now and go to case 2b).
 *
 * - When vhci_hcd receives RET_UNLINK,
 *
 *  - case 2a). a submit request is still pending in vhci_hcd.
 *      - urb was really pending in usbip.ko and urb_unlink_urb() was
 *        completed there.
 *      => free a pending submit request
 *      => notify unlink completeness by giving back the urb
 *
 *  - case 2b). a submit request is *not* pending in vhci_hcd.
 *      - urb was already given back to the core driver.
 *      => do not give back the urb
 *
 *
 * SERVER SIDE
 *
 * - When usbip receives CMD_UNLINK,
 *
 *  - case 3a). the urb of the unlink request is now in submission.
 *      => do usb_unlink_urb().
 *      => after the unlink is completed, send RET_UNLINK.
 *
 *  - case 3b). the urb of the unlink request is not in submission.
 *      - may be already completed or never be received
 *      => send RET_UNLINK
 *
 */
static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
    unsigned long flags;
    struct vhci_priv *priv;
    struct vhci_device *vdev;

    pr_info("dequeue a urb %p\n", urb);

    spin_lock_irqsave(&the_controller->lock, flags);

    priv = urb->hcpriv;
    if (!priv) {
        /* URB was never linked! or will be soon given back by
         * vhci_rx. */
        spin_unlock_irqrestore(&the_controller->lock, flags);
        return 0;
    }

    {
        int ret = 0;
        ret = usb_hcd_check_unlink_urb(hcd, urb, status);
        if (ret) {
            spin_unlock_irqrestore(&the_controller->lock, flags);
            return ret;
        }
    }

     /* send unlink request here? */
    vdev = priv->vdev;

    if (!vdev->ud.tcp_socket) {
        /* tcp connection is closed */
        unsigned long flags2;

        spin_lock_irqsave(&vdev->priv_lock, flags2);

        pr_info("device %p seems to be disconnected\n", vdev);
        list_del(&priv->list);
        kfree(priv);
        urb->hcpriv = NULL;

        spin_unlock_irqrestore(&vdev->priv_lock, flags2);

        /*
         * If tcp connection is alive, we have sent CMD_UNLINK.
         * vhci_rx will receive RET_UNLINK and give back the URB.
         * Otherwise, we give back it here.
         */
        pr_info("gives back urb %p\n", urb);

        usb_hcd_unlink_urb_from_ep(hcd, urb);

        spin_unlock_irqrestore(&the_controller->lock, flags);
        usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
                     urb->status);
        spin_lock_irqsave(&the_controller->lock, flags);

    } else {
        /* tcp connection is alive */
        unsigned long flags2;
        struct vhci_unlink *unlink;

        spin_lock_irqsave(&vdev->priv_lock, flags2);

        /* setup CMD_UNLINK pdu */
        unlink = kzalloc(sizeof(struct vhci_unlink), GFP_ATOMIC);
        if (!unlink) {
            pr_err("malloc vhci_unlink\n");
            spin_unlock_irqrestore(&vdev->priv_lock, flags2);
            spin_unlock_irqrestore(&the_controller->lock, flags);
            usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
            return -ENOMEM;
        }

        unlink->seqnum = atomic_inc_return(&the_controller->seqnum);
        if (unlink->seqnum == 0xffff)
            pr_info("seqnum max\n");

        unlink->unlink_seqnum = priv->seqnum;

        pr_info("device %p seems to be still connected\n", vdev);

        /* send cmd_unlink and try to cancel the pending URB in the
         * peer */
        list_add_tail(&unlink->list, &vdev->unlink_tx);
        wake_up(&vdev->waitq_tx);

        spin_unlock_irqrestore(&vdev->priv_lock, flags2);
    }

    spin_unlock_irqrestore(&the_controller->lock, flags);

    usbip_dbg_vhci_hc("leave\n");
    return 0;
}

static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
{
    struct vhci_unlink *unlink, *tmp;

    spin_lock(&the_controller->lock);
    spin_lock(&vdev->priv_lock);

    list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
        pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
        list_del(&unlink->list);
        kfree(unlink);
    }

    while (!list_empty(&vdev->unlink_rx)) {
        struct urb *urb;

        unlink = list_first_entry(&vdev->unlink_rx, struct vhci_unlink,
            list);

        /* give back URB of unanswered unlink request */
        pr_info("unlink cleanup rx %lu\n", unlink->unlink_seqnum);

        urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
        if (!urb) {
            pr_info("the urb (seqnum %lu) was already given back\n",
                unlink->unlink_seqnum);
            list_del(&unlink->list);
            kfree(unlink);
            continue;
        }

        urb->status = -ENODEV;

        usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);

        list_del(&unlink->list);

        spin_unlock(&vdev->priv_lock);
        spin_unlock(&the_controller->lock);

        usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
                     urb->status);

        spin_lock(&the_controller->lock);
        spin_lock(&vdev->priv_lock);

        kfree(unlink);
    }

    spin_unlock(&vdev->priv_lock);
    spin_unlock(&the_controller->lock);
}

/*
 * The important thing is that only one context begins cleanup.
 * This is why error handling and cleanup become simple.
 * We do not want to consider race condition as possible.
 */
static void vhci_shutdown_connection(struct usbip_device *ud)
{
    struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);

    /* need this? see stub_dev.c */
    if (ud->tcp_socket) {
        pr_debug("shutdown tcp_socket %p\n", ud->tcp_socket);
        kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
    }

    /* kill threads related to this sdev, if v.c. exists */
    if (vdev->ud.tcp_rx) {
        kthread_stop_put(vdev->ud.tcp_rx);
        vdev->ud.tcp_rx = NULL;
    }
    if (vdev->ud.tcp_tx) {
        kthread_stop_put(vdev->ud.tcp_tx);
        vdev->ud.tcp_tx = NULL;
    }
    pr_info("stop threads\n");

    /* active connection is closed */
    if (vdev->ud.tcp_socket != NULL) {
        sock_release(vdev->ud.tcp_socket);
        vdev->ud.tcp_socket = NULL;
    }
    pr_info("release socket\n");

    vhci_device_unlink_cleanup(vdev);

    /*
     * rh_port_disconnect() is a trigger of ...
     *   usb_disable_device():
     *  disable all the endpoints for a USB device.
     *   usb_disable_endpoint():
     *  disable endpoints. pending urbs are unlinked(dequeued).
     *
     * NOTE: After calling rh_port_disconnect(), the USB device drivers of a
     * detached device should release used urbs in a cleanup function (i.e.
     * xxx_disconnect()). Therefore, vhci_hcd does not need to release
     * pushed urbs and their private data in this function.
     *
     * NOTE: vhci_dequeue() must be considered carefully. When shutting down
     * a connection, vhci_shutdown_connection() expects vhci_dequeue()
     * gives back pushed urbs and frees their private data by request of
     * the cleanup function of a USB driver. When unlinking a urb with an
     * active connection, vhci_dequeue() does not give back the urb which
     * is actually given back by vhci_rx after receiving its return pdu.
     *
     */
    rh_port_disconnect(vdev->rhport);

    pr_info("disconnect device\n");
}


static void vhci_device_reset(struct usbip_device *ud)
{
    struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);

    spin_lock(&ud->lock);

    vdev->speed  = 0;
    vdev->devid  = 0;

    if (vdev->udev)
        usb_put_dev(vdev->udev);
    vdev->udev = NULL;

    ud->tcp_socket = NULL;
    ud->status = VDEV_ST_NULL;

    spin_unlock(&ud->lock);
}

static void vhci_device_unusable(struct usbip_device *ud)
{
    spin_lock(&ud->lock);
    ud->status = VDEV_ST_ERROR;
    spin_unlock(&ud->lock);
}

static void vhci_device_init(struct vhci_device *vdev)
{
    memset(vdev, 0, sizeof(*vdev));

    vdev->ud.side   = USBIP_VHCI;
    vdev->ud.status = VDEV_ST_NULL;
    spin_lock_init(&vdev->ud.lock);

    INIT_LIST_HEAD(&vdev->priv_rx);
    INIT_LIST_HEAD(&vdev->priv_tx);
    INIT_LIST_HEAD(&vdev->unlink_tx);
    INIT_LIST_HEAD(&vdev->unlink_rx);
    spin_lock_init(&vdev->priv_lock);

    init_waitqueue_head(&vdev->waitq_tx);

    vdev->ud.eh_ops.shutdown = vhci_shutdown_connection;
    vdev->ud.eh_ops.reset = vhci_device_reset;
    vdev->ud.eh_ops.unusable = vhci_device_unusable;

    usbip_start_eh(&vdev->ud);
}

static int vhci_start(struct usb_hcd *hcd)
{
    struct vhci_hcd *vhci = hcd_to_vhci(hcd);
    int rhport;
    int err = 0;

    usbip_dbg_vhci_hc("enter vhci_start\n");

    /* initialize private data of usb_hcd */

    for (rhport = 0; rhport < VHCI_NPORTS; rhport++) {
        struct vhci_device *vdev = &vhci->vdev[rhport];
        vhci_device_init(vdev);
        vdev->rhport = rhport;
    }

    atomic_set(&vhci->seqnum, 0);
    spin_lock_init(&vhci->lock);

    hcd->power_budget = 0; /* no limit */
    hcd->state  = HC_STATE_RUNNING;
    hcd->uses_new_polling = 1;

    /* vhci_hcd is now ready to be controlled through sysfs */
    err = sysfs_create_group(&vhci_dev(vhci)->kobj, &dev_attr_group);
    if (err) {
        pr_err("create sysfs files\n");
        return err;
    }

    return 0;
}

static void vhci_stop(struct usb_hcd *hcd)
{
    struct vhci_hcd *vhci = hcd_to_vhci(hcd);
    int rhport = 0;

    usbip_dbg_vhci_hc("stop VHCI controller\n");

    /* 1. remove the userland interface of vhci_hcd */
    sysfs_remove_group(&vhci_dev(vhci)->kobj, &dev_attr_group);

    /* 2. shutdown all the ports of vhci_hcd */
    for (rhport = 0 ; rhport < VHCI_NPORTS; rhport++) {
        struct vhci_device *vdev = &vhci->vdev[rhport];

        usbip_event_add(&vdev->ud, VDEV_EVENT_REMOVED);
        usbip_stop_eh(&vdev->ud);
    }
}

static int vhci_get_frame_number(struct usb_hcd *hcd)
{
    pr_err("Not yet implemented\n");
    return 0;
}

#ifdef CONFIG_PM

/* FIXME: suspend/resume */
static int vhci_bus_suspend(struct usb_hcd *hcd)
{
    struct vhci_hcd *vhci = hcd_to_vhci(hcd);

    dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);

    spin_lock_irq(&vhci->lock);
    /* vhci->rh_state = DUMMY_RH_SUSPENDED;
     * set_link_state(vhci); */
    hcd->state = HC_STATE_SUSPENDED;
    spin_unlock_irq(&vhci->lock);

    return 0;
}

static int vhci_bus_resume(struct usb_hcd *hcd)
{
    struct vhci_hcd *vhci = hcd_to_vhci(hcd);
    int rc = 0;

    dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);

    spin_lock_irq(&vhci->lock);
    if (!HCD_HW_ACCESSIBLE(hcd)) {
        rc = -ESHUTDOWN;
    } else {
        /* vhci->rh_state = DUMMY_RH_RUNNING;
         * set_link_state(vhci);
         * if (!list_empty(&vhci->urbp_list))
         *  mod_timer(&vhci->timer, jiffies); */
        hcd->state = HC_STATE_RUNNING;
    }
    spin_unlock_irq(&vhci->lock);

    return rc;
}

#else

#define vhci_bus_suspend      NULL
#define vhci_bus_resume       NULL
#endif

static struct hc_driver vhci_hc_driver = {
    .description    = driver_name,
    .product_desc   = driver_desc,
    .hcd_priv_size  = sizeof(struct vhci_hcd),

    .flags      = HCD_USB2,

    .start      = vhci_start,
    .stop       = vhci_stop,

    .urb_enqueue    = vhci_urb_enqueue,
    .urb_dequeue    = vhci_urb_dequeue,

    .get_frame_number = vhci_get_frame_number,

    .hub_status_data = vhci_hub_status,
    .hub_control    = vhci_hub_control,
    .bus_suspend    = vhci_bus_suspend,
    .bus_resume = vhci_bus_resume,
};

static int vhci_hcd_probe(struct platform_device *pdev)
{
    struct usb_hcd      *hcd;
    int         ret;

    usbip_dbg_vhci_hc("name %s id %d\n", pdev->name, pdev->id);

    /* will be removed */
    if (pdev->dev.dma_mask) {
        dev_info(&pdev->dev, "vhci_hcd DMA not supported\n");
        return -EINVAL;
    }

    /*
     * Allocate and initialize hcd.
     * Our private data is also allocated automatically.
     */
    hcd = usb_create_hcd(&vhci_hc_driver, &pdev->dev, dev_name(&pdev->dev));
    if (!hcd) {
        pr_err("create hcd failed\n");
        return -ENOMEM;
    }
    hcd->has_tt = 1;

    /* this is private data for vhci_hcd */
    the_controller = hcd_to_vhci(hcd);

    /*
     * Finish generic HCD structure initialization and register.
     * Call the driver's reset() and start() routines.
     */
    ret = usb_add_hcd(hcd, 0, 0);
    if (ret != 0) {
        pr_err("usb_add_hcd failed %d\n", ret);
        usb_put_hcd(hcd);
        the_controller = NULL;
        return ret;
    }

    usbip_dbg_vhci_hc("bye\n");
    return 0;
}

static int vhci_hcd_remove(struct platform_device *pdev)
{
    struct usb_hcd  *hcd;

    hcd = platform_get_drvdata(pdev);
    if (!hcd)
        return 0;

    /*
     * Disconnects the root hub,
     * then reverses the effects of usb_add_hcd(),
     * invoking the HCD's stop() methods.
     */
    usb_remove_hcd(hcd);
    usb_put_hcd(hcd);
    the_controller = NULL;

    return 0;
}

#ifdef CONFIG_PM

/* what should happen for USB/IP under suspend/resume? */
static int vhci_hcd_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct usb_hcd *hcd;
    int rhport = 0;
    int connected = 0;
    int ret = 0;

    hcd = platform_get_drvdata(pdev);

    spin_lock(&the_controller->lock);

    for (rhport = 0; rhport < VHCI_NPORTS; rhport++)
        if (the_controller->port_status[rhport] &
            USB_PORT_STAT_CONNECTION)
            connected += 1;

    spin_unlock(&the_controller->lock);

    if (connected > 0) {
        dev_info(&pdev->dev, "We have %d active connection%s. Do not "
             "suspend.\n", connected, (connected == 1 ? "" : "s"));
        ret =  -EBUSY;
    } else {
        dev_info(&pdev->dev, "suspend vhci_hcd");
        clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
    }

    return ret;
}

static int vhci_hcd_resume(struct platform_device *pdev)
{
    struct usb_hcd *hcd;

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

    hcd = platform_get_drvdata(pdev);
    set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
    usb_hcd_poll_rh_status(hcd);

    return 0;
}

#else

#define vhci_hcd_suspend    NULL
#define vhci_hcd_resume     NULL

#endif

static struct platform_driver vhci_driver = {
    .probe  = vhci_hcd_probe,
    .remove = __devexit_p(vhci_hcd_remove),
    .suspend = vhci_hcd_suspend,
    .resume = vhci_hcd_resume,
    .driver = {
        .name = (char *) driver_name,
        .owner = THIS_MODULE,
    },
};

/*
 * The VHCI 'device' is 'virtual'; not a real plug&play hardware.
 * We need to add this virtual device as a platform device arbitrarily:
 *  1. platform_device_register()
 */
static void the_pdev_release(struct device *dev)
{
    return;
}

static struct platform_device the_pdev = {
    /* should be the same name as driver_name */
    .name = (char *) driver_name,
    .id = -1,
    .dev = {
        /* .driver = &vhci_driver, */
        .release = the_pdev_release,
    },
};

static int __init vhci_hcd_init(void)
{
    int ret;

    if (usb_disabled())
        return -ENODEV;

    ret = platform_driver_register(&vhci_driver);
    if (ret < 0)
        goto err_driver_register;

    ret = platform_device_register(&the_pdev);
    if (ret < 0)
        goto err_platform_device_register;

    pr_info(DRIVER_DESC " v" USBIP_VERSION "\n");
    return ret;

err_platform_device_register:
    platform_driver_unregister(&vhci_driver);
err_driver_register:
    return ret;
}

static void __exit vhci_hcd_exit(void)
{
    platform_device_unregister(&the_pdev);
    platform_driver_unregister(&vhci_driver);
}

module_init(vhci_hcd_init);
module_exit(vhci_hcd_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(USBIP_VERSION);