usbip: move usbip kernel code out of staging
[cascardo/linux.git] / drivers / usb / usbip / vhci_hcd.c
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
new file mode 100644 (file)
index 0000000..c02374b
--- /dev/null
@@ -0,0 +1,1171 @@
+/*
+ * 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/file.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)
+{
+       usbip_dbg_vhci_rh("rh_port_connect %d\n", rhport);
+
+       spin_lock(&the_controller->lock);
+
+       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_unlock(&the_controller->lock);
+
+       usb_hcd_poll_rh_status(vhci_to_hcd(the_controller));
+}
+
+static void rh_port_disconnect(int rhport)
+{
+       usbip_dbg_vhci_rh("rh_port_disconnect %d\n", rhport);
+
+       spin_lock(&the_controller->lock);
+
+       the_controller->port_status[rhport] &= ~USB_PORT_STAT_CONNECTION;
+       the_controller->port_status[rhport] |=
+                                       (1 << USB_PORT_FEAT_C_CONNECTION);
+
+       spin_unlock(&the_controller->lock);
+       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;
+       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(&vhci->lock);
+       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;
+               }
+       }
+
+       if ((hcd->state == HC_STATE_SUSPENDED) && (changed == 1))
+               usb_hcd_resume_root_hub(hcd);
+
+done:
+       spin_unlock(&vhci->lock);
+       return changed ? retval : 0;
+}
+
+static inline void hub_descriptor(struct usb_hub_descriptor *desc)
+{
+       memset(desc, 0, sizeof(*desc));
+       desc->bDescriptorType = 0x29;
+       desc->bDescLength = 9;
+       desc->wHubCharacteristics = (__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;
+       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(&dum->lock);
+
+       /* 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->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 = 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 not care about 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->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;
+                       }
+               }
+               ((__le16 *) buf)[0] = cpu_to_le16(dum->port_status[rhport]);
+               ((__le16 *) 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");
+
+               /* "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(&dum->lock);
+
+       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;
+
+       if (!vdev) {
+               pr_err("could not get virtual device");
+               return;
+       }
+
+       priv = kzalloc(sizeof(struct vhci_priv), GFP_ATOMIC);
+       if (!priv) {
+               usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
+               return;
+       }
+
+       spin_lock(&vdev->priv_lock);
+
+       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(&vdev->priv_lock);
+}
+
+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;
+       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(&the_controller->lock);
+
+       if (urb->status != -EINPROGRESS) {
+               dev_err(dev, "URB already unlinked!, status %d\n", urb->status);
+               spin_unlock(&the_controller->lock);
+               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(&the_controller->lock);
+               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 == cpu_to_le16(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(&the_controller->lock);
+
+       return 0;
+
+no_need_xmit:
+       usb_hcd_unlink_urb_from_ep(hcd, urb);
+no_need_unlink:
+       spin_unlock(&the_controller->lock);
+       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)
+{
+       struct vhci_priv *priv;
+       struct vhci_device *vdev;
+
+       pr_info("dequeue a urb %p\n", urb);
+
+       spin_lock(&the_controller->lock);
+
+       priv = urb->hcpriv;
+       if (!priv) {
+               /* URB was never linked! or will be soon given back by
+                * vhci_rx. */
+               spin_unlock(&the_controller->lock);
+               return 0;
+       }
+
+       {
+               int ret = 0;
+
+               ret = usb_hcd_check_unlink_urb(hcd, urb, status);
+               if (ret) {
+                       spin_unlock(&the_controller->lock);
+                       return ret;
+               }
+       }
+
+        /* send unlink request here? */
+       vdev = priv->vdev;
+
+       if (!vdev->ud.tcp_socket) {
+               /* tcp connection is closed */
+               spin_lock(&vdev->priv_lock);
+
+               pr_info("device %p seems to be disconnected\n", vdev);
+               list_del(&priv->list);
+               kfree(priv);
+               urb->hcpriv = NULL;
+
+               spin_unlock(&vdev->priv_lock);
+
+               /*
+                * 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(&the_controller->lock);
+               usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
+                                    urb->status);
+               spin_lock(&the_controller->lock);
+
+       } else {
+               /* tcp connection is alive */
+               struct vhci_unlink *unlink;
+
+               spin_lock(&vdev->priv_lock);
+
+               /* setup CMD_UNLINK pdu */
+               unlink = kzalloc(sizeof(struct vhci_unlink), GFP_ATOMIC);
+               if (!unlink) {
+                       spin_unlock(&vdev->priv_lock);
+                       spin_unlock(&the_controller->lock);
+                       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(&vdev->priv_lock);
+       }
+
+       spin_unlock(&the_controller->lock);
+
+       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 (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) {
+               sockfd_put(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;
+
+       if (ud->tcp_socket) {
+               sockfd_put(ud->tcp_socket);
+               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->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(&vhci->lock);
+       hcd->state = HC_STATE_SUSPENDED;
+       spin_unlock(&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(&vhci->lock);
+       if (!HCD_HW_ACCESSIBLE(hcd))
+               rc = -ESHUTDOWN;
+       else
+               hcd->state = HC_STATE_RUNNING;
+       spin_unlock(&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);
+
+       /*
+        * 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 = vhci_hcd_remove,
+       .suspend = vhci_hcd_suspend,
+       .resume = vhci_hcd_resume,
+       .driver = {
+               .name = 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)
+{
+}
+
+static struct platform_device the_pdev = {
+       /* should be the same name as driver_name */
+       .name = driver_name,
+       .id = -1,
+       .dev = {
+               .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)
+               goto err_driver_register;
+
+       ret = platform_device_register(&the_pdev);
+       if (ret)
+               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);