/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1996-2000 Whistle Communications, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of author nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY NICK HIBMA AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

/* Driver for arbitrary double bulk pipe devices.
 * The driver assumes that there will be the same driver on the other side.
 *
 * XXX Some more information on what the framing of the IP packets looks like.
 *
 * To take full advantage of bulk transmission, packets should be chosen
 * between 1k and 5k in size (1k to make sure the sending side starts
 * streaming, and <5k to avoid overflowing the system with small TDs).
 */

/* probe/attach/detach:
 *  Connect the driver to the hardware and netgraph
 *
 *  The reason we submit a bulk in transfer is that USB does not know about
 *  interrupts. The bulk transfer continuously polls the device for data.
 *  While the device has no data available, the device NAKs the TDs. As soon
 *  as there is data, the transfer happens and the data comes flowing in.
 *
 *  In case you were wondering, interrupt transfers happen exactly that way.
 *  It therefore doesn't make sense to use the interrupt pipe to signal
 *  'data ready' and then schedule a bulk transfer to fetch it. That would
 *  incur a 2ms delay at least, without reducing bandwidth requirements.
 *
 */

#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdi_util.h>
#include "usbdevs.h"

#define USB_DEBUG_VAR udbp_debug
#include <dev/usb/usb_debug.h>

#include <sys/mbuf.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>
#include <netgraph/bluetooth/include/ng_bluetooth.h>

#include <dev/usb/misc/udbp.h>

#ifdef USB_DEBUG
static int udbp_debug = 0;

static SYSCTL_NODE(_hw_usb, OID_AUTO, udbp, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "USB udbp");
SYSCTL_INT(_hw_usb_udbp, OID_AUTO, debug, CTLFLAG_RWTUN,
    &udbp_debug, 0, "udbp debug level");
#endif

#define UDBP_TIMEOUT    2000            /* timeout on outbound transfers, in
                                         * msecs */
#define UDBP_BUFFERSIZE MCLBYTES        /* maximum number of bytes in one
                                         * transfer */
#define UDBP_T_WR       0
#define UDBP_T_RD       1
#define UDBP_T_WR_CS    2
#define UDBP_T_RD_CS    3
#define UDBP_T_MAX      4
#define UDBP_Q_MAXLEN   50

struct udbp_softc {
        struct mtx sc_mtx;
        struct ng_bt_mbufq sc_xmitq_hipri;      /* hi-priority transmit queue */
        struct ng_bt_mbufq sc_xmitq;    /* low-priority transmit queue */

        struct usb_xfer *sc_xfer[UDBP_T_MAX];
        node_p  sc_node;                /* back pointer to node */
        hook_p  sc_hook;                /* pointer to the hook */
        struct mbuf *sc_bulk_in_buffer;

        uint32_t sc_packets_in;         /* packets in from downstream */
        uint32_t sc_packets_out;        /* packets out towards downstream */

        uint8_t sc_flags;
#define UDBP_FLAG_READ_STALL    0x01    /* read transfer stalled */
#define UDBP_FLAG_WRITE_STALL   0x02    /* write transfer stalled */

        uint8_t sc_name[16];
};

/* prototypes */

static int udbp_modload(module_t mod, int event, void *data);

static device_probe_t udbp_probe;
static device_attach_t udbp_attach;
static device_detach_t udbp_detach;

static usb_callback_t udbp_bulk_read_callback;
static usb_callback_t udbp_bulk_read_clear_stall_callback;
static usb_callback_t udbp_bulk_write_callback;
static usb_callback_t udbp_bulk_write_clear_stall_callback;

static void     udbp_bulk_read_complete(node_p, hook_p, void *, int);

static ng_constructor_t ng_udbp_constructor;
static ng_rcvmsg_t      ng_udbp_rcvmsg;
static ng_shutdown_t    ng_udbp_rmnode;
static ng_newhook_t     ng_udbp_newhook;
static ng_connect_t     ng_udbp_connect;
static ng_rcvdata_t     ng_udbp_rcvdata;
static ng_disconnect_t  ng_udbp_disconnect;

/* Parse type for struct ngudbpstat */
static const struct ng_parse_struct_field
        ng_udbp_stat_type_fields[] = NG_UDBP_STATS_TYPE_INFO;

static const struct ng_parse_type ng_udbp_stat_type = {
        &ng_parse_struct_type,
        &ng_udbp_stat_type_fields
};

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_udbp_cmdlist[] = {
        {
                NGM_UDBP_COOKIE,
                NGM_UDBP_GET_STATUS,
                "getstatus",
                NULL,
                &ng_udbp_stat_type,
        },
        {
                NGM_UDBP_COOKIE,
                NGM_UDBP_SET_FLAG,
                "setflag",
                &ng_parse_int32_type,
                NULL
        },
        {0}
};

/* Netgraph node type descriptor */
static struct ng_type ng_udbp_typestruct = {
        .version = NG_ABI_VERSION,
        .name = NG_UDBP_NODE_TYPE,
        .constructor = ng_udbp_constructor,
        .rcvmsg = ng_udbp_rcvmsg,
        .shutdown = ng_udbp_rmnode,
        .newhook = ng_udbp_newhook,
        .connect = ng_udbp_connect,
        .rcvdata = ng_udbp_rcvdata,
        .disconnect = ng_udbp_disconnect,
        .cmdlist = ng_udbp_cmdlist,
};

/* USB config */
static const struct usb_config udbp_config[UDBP_T_MAX] = {
        [UDBP_T_WR] = {
                .type = UE_BULK,
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_OUT,
                .bufsize = UDBP_BUFFERSIZE,
                .flags = {.pipe_bof = 1,.force_short_xfer = 1,},
                .callback = &udbp_bulk_write_callback,
                .timeout = UDBP_TIMEOUT,
        },

        [UDBP_T_RD] = {
                .type = UE_BULK,
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_IN,
                .bufsize = UDBP_BUFFERSIZE,
                .flags = {.pipe_bof = 1,.short_xfer_ok = 1,},
                .callback = &udbp_bulk_read_callback,
        },

        [UDBP_T_WR_CS] = {
                .type = UE_CONTROL,
                .endpoint = 0x00,       /* Control pipe */
                .direction = UE_DIR_ANY,
                .bufsize = sizeof(struct usb_device_request),
                .callback = &udbp_bulk_write_clear_stall_callback,
                .timeout = 1000,        /* 1 second */
                .interval = 50, /* 50ms */
        },

        [UDBP_T_RD_CS] = {
                .type = UE_CONTROL,
                .endpoint = 0x00,       /* Control pipe */
                .direction = UE_DIR_ANY,
                .bufsize = sizeof(struct usb_device_request),
                .callback = &udbp_bulk_read_clear_stall_callback,
                .timeout = 1000,        /* 1 second */
                .interval = 50, /* 50ms */
        },
};

static device_method_t udbp_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe, udbp_probe),
        DEVMETHOD(device_attach, udbp_attach),
        DEVMETHOD(device_detach, udbp_detach),

        DEVMETHOD_END
};

static driver_t udbp_driver = {
        .name = "udbp",
        .methods = udbp_methods,
        .size = sizeof(struct udbp_softc),
};

static const STRUCT_USB_HOST_ID udbp_devs[] = {
        {USB_VPI(USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_F5U258, 0)},
        {USB_VPI(USB_VENDOR_NETCHIP, USB_PRODUCT_NETCHIP_TURBOCONNECT, 0)},
        {USB_VPI(USB_VENDOR_NETCHIP, USB_PRODUCT_NETCHIP_GADGETZERO, 0)},
        {USB_VPI(USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2301, 0)},
        {USB_VPI(USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL2302, 0)},
        {USB_VPI(USB_VENDOR_PROLIFIC, USB_PRODUCT_PROLIFIC_PL27A1, 0)},
        {USB_VPI(USB_VENDOR_ANCHOR, USB_PRODUCT_ANCHOR_EZLINK, 0)},
        {USB_VPI(USB_VENDOR_GENESYS, USB_PRODUCT_GENESYS_GL620USB, 0)},
};

DRIVER_MODULE(udbp, uhub, udbp_driver, udbp_modload, NULL);
MODULE_DEPEND(udbp, netgraph, NG_ABI_VERSION, NG_ABI_VERSION, NG_ABI_VERSION);
MODULE_DEPEND(udbp, usb, 1, 1, 1);
MODULE_VERSION(udbp, 1);
USB_PNP_HOST_INFO(udbp_devs);

static int
udbp_modload(module_t mod, int event, void *data)
{
        int error;

        switch (event) {
        case MOD_LOAD:
                error = ng_newtype(&ng_udbp_typestruct);
                if (error != 0) {
                        printf("%s: Could not register "
                            "Netgraph node type, error=%d\n",
                            NG_UDBP_NODE_TYPE, error);
                }
                break;

        case MOD_UNLOAD:
                error = ng_rmtype(&ng_udbp_typestruct);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }
        return (error);
}

static int
udbp_probe(device_t dev)
{
        struct usb_attach_arg *uaa = device_get_ivars(dev);

        if (uaa->usb_mode != USB_MODE_HOST)
                return (ENXIO);
        if (uaa->info.bConfigIndex != 0)
                return (ENXIO);
        if (uaa->info.bIfaceIndex != 0)
                return (ENXIO);

        return (usbd_lookup_id_by_uaa(udbp_devs, sizeof(udbp_devs), uaa));
}

static int
udbp_attach(device_t dev)
{
        struct usb_attach_arg *uaa = device_get_ivars(dev);
        struct udbp_softc *sc = device_get_softc(dev);
        int error;

        device_set_usb_desc(dev);

        snprintf(sc->sc_name, sizeof(sc->sc_name),
            "%s", device_get_nameunit(dev));

        mtx_init(&sc->sc_mtx, "udbp lock", NULL, MTX_DEF | MTX_RECURSE);

        error = usbd_transfer_setup(uaa->device, &uaa->info.bIfaceIndex,
            sc->sc_xfer, udbp_config, UDBP_T_MAX, sc, &sc->sc_mtx);
        if (error) {
                DPRINTF("error=%s\n", usbd_errstr(error));
                goto detach;
        }
        NG_BT_MBUFQ_INIT(&sc->sc_xmitq, UDBP_Q_MAXLEN);

        NG_BT_MBUFQ_INIT(&sc->sc_xmitq_hipri, UDBP_Q_MAXLEN);

        /* create Netgraph node */

        if (ng_make_node_common(&ng_udbp_typestruct, &sc->sc_node) != 0) {
                printf("%s: Could not create Netgraph node\n",
                    sc->sc_name);
                sc->sc_node = NULL;
                goto detach;
        }
        /* name node */

        if (ng_name_node(sc->sc_node, sc->sc_name) != 0) {
                printf("%s: Could not name node\n",
                    sc->sc_name);
                NG_NODE_UNREF(sc->sc_node);
                sc->sc_node = NULL;
                goto detach;
        }
        NG_NODE_SET_PRIVATE(sc->sc_node, sc);

        /* the device is now operational */

        return (0);                     /* success */

detach:
        udbp_detach(dev);
        return (ENOMEM);                /* failure */
}

static int
udbp_detach(device_t dev)
{
        struct udbp_softc *sc = device_get_softc(dev);

        /* destroy Netgraph node */

        if (sc->sc_node != NULL) {
                NG_NODE_SET_PRIVATE(sc->sc_node, NULL);
                ng_rmnode_self(sc->sc_node);
                sc->sc_node = NULL;
        }
        /* free USB transfers, if any */

        usbd_transfer_unsetup(sc->sc_xfer, UDBP_T_MAX);

        mtx_destroy(&sc->sc_mtx);

        /* destroy queues */

        NG_BT_MBUFQ_DESTROY(&sc->sc_xmitq);
        NG_BT_MBUFQ_DESTROY(&sc->sc_xmitq_hipri);

        /* extra check */

        if (sc->sc_bulk_in_buffer) {
                m_freem(sc->sc_bulk_in_buffer);
                sc->sc_bulk_in_buffer = NULL;
        }
        return (0);                     /* success */
}

static void
udbp_bulk_read_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct udbp_softc *sc = usbd_xfer_softc(xfer);
        struct usb_page_cache *pc;
        struct mbuf *m;
        int actlen;

        usbd_xfer_status(xfer, &actlen, NULL, NULL, NULL);

        switch (USB_GET_STATE(xfer)) {
        case USB_ST_TRANSFERRED:

                /* allocate new mbuf */

                MGETHDR(m, M_NOWAIT, MT_DATA);

                if (m == NULL) {
                        goto tr_setup;
                }

                if (!(MCLGET(m, M_NOWAIT))) {
                        m_freem(m);
                        goto tr_setup;
                }
                m->m_pkthdr.len = m->m_len = actlen;

                pc = usbd_xfer_get_frame(xfer, 0);
                usbd_copy_out(pc, 0, m->m_data, actlen);

                sc->sc_bulk_in_buffer = m;

                DPRINTF("received package %d bytes\n", actlen);

        case USB_ST_SETUP:
tr_setup:
                if (sc->sc_bulk_in_buffer) {
                        ng_send_fn(sc->sc_node, NULL, &udbp_bulk_read_complete, NULL, 0);
                        return;
                }
                if (sc->sc_flags & UDBP_FLAG_READ_STALL) {
                        usbd_transfer_start(sc->sc_xfer[UDBP_T_RD_CS]);
                        return;
                }
                usbd_xfer_set_frame_len(xfer, 0, usbd_xfer_max_len(xfer));
                usbd_transfer_submit(xfer);
                return;

        default:                        /* Error */
                if (error != USB_ERR_CANCELLED) {
                        /* try to clear stall first */
                        sc->sc_flags |= UDBP_FLAG_READ_STALL;
                        usbd_transfer_start(sc->sc_xfer[UDBP_T_RD_CS]);
                }
                return;
        }
}

static void
udbp_bulk_read_clear_stall_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct udbp_softc *sc = usbd_xfer_softc(xfer);
        struct usb_xfer *xfer_other = sc->sc_xfer[UDBP_T_RD];

        if (usbd_clear_stall_callback(xfer, xfer_other)) {
                DPRINTF("stall cleared\n");
                sc->sc_flags &= ~UDBP_FLAG_READ_STALL;
                usbd_transfer_start(xfer_other);
        }
}

static void
udbp_bulk_read_complete(node_p node, hook_p hook, void *arg1, int arg2)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(node);
        struct mbuf *m;
        int error;

        if (sc == NULL) {
                return;
        }
        mtx_lock(&sc->sc_mtx);

        m = sc->sc_bulk_in_buffer;

        if (m) {
                sc->sc_bulk_in_buffer = NULL;

                if ((sc->sc_hook == NULL) ||
                    NG_HOOK_NOT_VALID(sc->sc_hook)) {
                        DPRINTF("No upstream hook\n");
                        goto done;
                }
                sc->sc_packets_in++;

                NG_SEND_DATA_ONLY(error, sc->sc_hook, m);

                m = NULL;
        }
done:
        if (m) {
                m_freem(m);
        }
        /* start USB bulk-in transfer, if not already started */

        usbd_transfer_start(sc->sc_xfer[UDBP_T_RD]);

        mtx_unlock(&sc->sc_mtx);
}

static void
udbp_bulk_write_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct udbp_softc *sc = usbd_xfer_softc(xfer);
        struct usb_page_cache *pc;
        struct mbuf *m;

        switch (USB_GET_STATE(xfer)) {
        case USB_ST_TRANSFERRED:

                sc->sc_packets_out++;

        case USB_ST_SETUP:
                if (sc->sc_flags & UDBP_FLAG_WRITE_STALL) {
                        usbd_transfer_start(sc->sc_xfer[UDBP_T_WR_CS]);
                        return;
                }
                /* get next mbuf, if any */

                NG_BT_MBUFQ_DEQUEUE(&sc->sc_xmitq_hipri, m);
                if (m == NULL) {
                        NG_BT_MBUFQ_DEQUEUE(&sc->sc_xmitq, m);
                        if (m == NULL) {
                                DPRINTF("Data queue is empty\n");
                                return;
                        }
                }
                if (m->m_pkthdr.len > MCLBYTES) {
                        DPRINTF("truncating large packet "
                            "from %d to %d bytes\n", m->m_pkthdr.len,
                            MCLBYTES);
                        m->m_pkthdr.len = MCLBYTES;
                }
                pc = usbd_xfer_get_frame(xfer, 0);
                usbd_m_copy_in(pc, 0, m, 0, m->m_pkthdr.len);

                usbd_xfer_set_frame_len(xfer, 0, m->m_pkthdr.len);

                DPRINTF("packet out: %d bytes\n", m->m_pkthdr.len);

                m_freem(m);

                usbd_transfer_submit(xfer);
                return;

        default:                        /* Error */
                if (error != USB_ERR_CANCELLED) {
                        /* try to clear stall first */
                        sc->sc_flags |= UDBP_FLAG_WRITE_STALL;
                        usbd_transfer_start(sc->sc_xfer[UDBP_T_WR_CS]);
                }
                return;
        }
}

static void
udbp_bulk_write_clear_stall_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct udbp_softc *sc = usbd_xfer_softc(xfer);
        struct usb_xfer *xfer_other = sc->sc_xfer[UDBP_T_WR];

        if (usbd_clear_stall_callback(xfer, xfer_other)) {
                DPRINTF("stall cleared\n");
                sc->sc_flags &= ~UDBP_FLAG_WRITE_STALL;
                usbd_transfer_start(xfer_other);
        }
}

/***********************************************************************
 * Start of Netgraph methods
 **********************************************************************/

/*
 * If this is a device node so this work is done in the attach()
 * routine and the constructor will return EINVAL as you should not be able
 * to create nodes that depend on hardware (unless you can add the hardware :)
 */
static int
ng_udbp_constructor(node_p node)
{
        return (EINVAL);
}

/*
 * Give our ok for a hook to be added...
 * If we are not running this might kick a device into life.
 * Possibly decode information out of the hook name.
 * Add the hook's private info to the hook structure.
 * (if we had some). In this example, we assume that there is a
 * an array of structs, called 'channel' in the private info,
 * one for each active channel. The private
 * pointer of each hook points to the appropriate UDBP_hookinfo struct
 * so that the source of an input packet is easily identified.
 */
static int
ng_udbp_newhook(node_p node, hook_p hook, const char *name)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(node);
        int32_t error = 0;

        if (strcmp(name, NG_UDBP_HOOK_NAME)) {
                return (EINVAL);
        }
        mtx_lock(&sc->sc_mtx);

        if (sc->sc_hook != NULL) {
                error = EISCONN;
        } else {
                sc->sc_hook = hook;
                NG_HOOK_SET_PRIVATE(hook, NULL);
        }

        mtx_unlock(&sc->sc_mtx);

        return (error);
}

/*
 * Get a netgraph control message.
 * Check it is one we understand. If needed, send a response.
 * We could save the address for an async action later, but don't here.
 * Always free the message.
 * The response should be in a malloc'd region that the caller can 'free'.
 * A response is not required.
 * Theoretically you could respond defferently to old message types if
 * the cookie in the header didn't match what we consider to be current
 * (so that old userland programs could continue to work).
 */
static int
ng_udbp_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(node);
        struct ng_mesg *resp = NULL;
        int error = 0;
        struct ng_mesg *msg;

        NGI_GET_MSG(item, msg);
        /* Deal with message according to cookie and command */
        switch (msg->header.typecookie) {
        case NGM_UDBP_COOKIE:
                switch (msg->header.cmd) {
                case NGM_UDBP_GET_STATUS:
                        {
                                struct ngudbpstat *stats;

                                NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
                                if (!resp) {
                                        error = ENOMEM;
                                        break;
                                }
                                stats = (struct ngudbpstat *)resp->data;
                                mtx_lock(&sc->sc_mtx);
                                stats->packets_in = sc->sc_packets_in;
                                stats->packets_out = sc->sc_packets_out;
                                mtx_unlock(&sc->sc_mtx);
                                break;
                        }
                case NGM_UDBP_SET_FLAG:
                        if (msg->header.arglen != sizeof(uint32_t)) {
                                error = EINVAL;
                                break;
                        }
                        DPRINTF("flags = 0x%08x\n",
                            *((uint32_t *)msg->data));
                        break;
                default:
                        error = EINVAL; /* unknown command */
                        break;
                }
                break;
        default:
                error = EINVAL;         /* unknown cookie type */
                break;
        }

        /* Take care of synchronous response, if any */
        NG_RESPOND_MSG(error, node, item, resp);
        NG_FREE_MSG(msg);
        return (error);
}

/*
 * Accept data from the hook and queue it for output.
 */
static int
ng_udbp_rcvdata(hook_p hook, item_p item)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
        struct ng_bt_mbufq *queue_ptr;
        struct mbuf *m;
        struct ng_tag_prio *ptag;
        int error;

        if (sc == NULL) {
                NG_FREE_ITEM(item);
                return (EHOSTDOWN);
        }
        NGI_GET_M(item, m);
        NG_FREE_ITEM(item);

        /*
         * Now queue the data for when it can be sent
         */
        ptag = (void *)m_tag_locate(m, NGM_GENERIC_COOKIE,
            NG_TAG_PRIO, NULL);

        if (ptag && (ptag->priority > NG_PRIO_CUTOFF))
                queue_ptr = &sc->sc_xmitq_hipri;
        else
                queue_ptr = &sc->sc_xmitq;

        mtx_lock(&sc->sc_mtx);

        if (NG_BT_MBUFQ_FULL(queue_ptr)) {
                NG_BT_MBUFQ_DROP(queue_ptr);
                NG_FREE_M(m);
                error = ENOBUFS;
        } else {
                NG_BT_MBUFQ_ENQUEUE(queue_ptr, m);
                /*
                 * start bulk-out transfer, if not already started:
                 */
                usbd_transfer_start(sc->sc_xfer[UDBP_T_WR]);
                error = 0;
        }

        mtx_unlock(&sc->sc_mtx);

        return (error);
}

/*
 * Do local shutdown processing..
 * We are a persistent device, we refuse to go away, and
 * only remove our links and reset ourself.
 */
static int
ng_udbp_rmnode(node_p node)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(node);

        /* Let old node go */
        NG_NODE_SET_PRIVATE(node, NULL);
        NG_NODE_UNREF(node);            /* forget it ever existed */

        if (sc == NULL) {
                goto done;
        }
        /* Create Netgraph node */
        if (ng_make_node_common(&ng_udbp_typestruct, &sc->sc_node) != 0) {
                printf("%s: Could not create Netgraph node\n",
                    sc->sc_name);
                sc->sc_node = NULL;
                goto done;
        }
        /* Name node */
        if (ng_name_node(sc->sc_node, sc->sc_name) != 0) {
                printf("%s: Could not name Netgraph node\n",
                    sc->sc_name);
                NG_NODE_UNREF(sc->sc_node);
                sc->sc_node = NULL;
                goto done;
        }
        NG_NODE_SET_PRIVATE(sc->sc_node, sc);

done:
        if (sc) {
                mtx_unlock(&sc->sc_mtx);
        }
        return (0);
}

/*
 * This is called once we've already connected a new hook to the other node.
 * It gives us a chance to balk at the last minute.
 */
static int
ng_udbp_connect(hook_p hook)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

        /* force outward queueing */
        NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));

        mtx_lock(&sc->sc_mtx);

        sc->sc_flags |= (UDBP_FLAG_READ_STALL |
            UDBP_FLAG_WRITE_STALL);

        /* start bulk-in transfer */
        usbd_transfer_start(sc->sc_xfer[UDBP_T_RD]);

        /* start bulk-out transfer */
        usbd_transfer_start(sc->sc_xfer[UDBP_T_WR]);

        mtx_unlock(&sc->sc_mtx);

        return (0);
}

/*
 * Dook disconnection
 *
 * For this type, removal of the last link destroys the node
 */
static int
ng_udbp_disconnect(hook_p hook)
{
        struct udbp_softc *sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
        int error = 0;

        if (sc != NULL) {
                mtx_lock(&sc->sc_mtx);

                if (hook != sc->sc_hook) {
                        error = EINVAL;
                } else {
                        /* stop bulk-in transfer */
                        usbd_transfer_stop(sc->sc_xfer[UDBP_T_RD_CS]);
                        usbd_transfer_stop(sc->sc_xfer[UDBP_T_RD]);

                        /* stop bulk-out transfer */
                        usbd_transfer_stop(sc->sc_xfer[UDBP_T_WR_CS]);
                        usbd_transfer_stop(sc->sc_xfer[UDBP_T_WR]);

                        /* cleanup queues */
                        NG_BT_MBUFQ_DRAIN(&sc->sc_xmitq);
                        NG_BT_MBUFQ_DRAIN(&sc->sc_xmitq_hipri);

                        if (sc->sc_bulk_in_buffer) {
                                m_freem(sc->sc_bulk_in_buffer);
                                sc->sc_bulk_in_buffer = NULL;
                        }
                        sc->sc_hook = NULL;
                }

                mtx_unlock(&sc->sc_mtx);
        }
        if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
            && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
                ng_rmnode_self(NG_HOOK_NODE(hook));

        return (error);
}