kernel - Remove mplock from KTRACE paths

[dragonfly.git] / sys / kern / subr_bus.c

/*
 * Copyright (c) 1997,1998 Doug Rabson
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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.
 *
 * $FreeBSD: src/sys/kern/subr_bus.c,v 1.54.2.9 2002/10/10 15:13:32 jhb Exp $
 */

#include "opt_bus.h"

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/kobj.h>
#include <sys/bus_private.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/rman.h>
#include <sys/device.h>
#include <sys/lock.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/filio.h>
#include <sys/event.h>
#include <sys/signalvar.h>
#include <sys/machintr.h>
#include <sys/vnode.h>

#include <machine/stdarg.h>     /* for device_printf() */

#include <sys/thread2.h>
#include <sys/mplock2.h>

SYSCTL_NODE(_hw, OID_AUTO, bus, CTLFLAG_RW, NULL, NULL);
SYSCTL_NODE(, OID_AUTO, dev, CTLFLAG_RW, NULL, NULL);

MALLOC_DEFINE(M_BUS, "bus", "Bus data structures");

#ifdef BUS_DEBUG
#define PDEBUG(a)       (kprintf("%s:%d: ", __func__, __LINE__), kprintf a, kprintf("\n"))
#define DEVICENAME(d)   ((d)? device_get_name(d): "no device")
#define DRIVERNAME(d)   ((d)? d->name : "no driver")
#define DEVCLANAME(d)   ((d)? d->name : "no devclass")

/* Produce the indenting, indent*2 spaces plus a '.' ahead of that to 
 * prevent syslog from deleting initial spaces
 */
#define indentprintf(p) do { int iJ; kprintf("."); for (iJ=0; iJ<indent; iJ++) kprintf("  "); kprintf p ; } while(0)

static void     print_device_short(device_t dev, int indent);
static void     print_device(device_t dev, int indent);
void            print_device_tree_short(device_t dev, int indent);
void            print_device_tree(device_t dev, int indent);
static void     print_driver_short(driver_t *driver, int indent);
static void     print_driver(driver_t *driver, int indent);
static void     print_driver_list(driver_list_t drivers, int indent);
static void     print_devclass_short(devclass_t dc, int indent);
static void     print_devclass(devclass_t dc, int indent);
void            print_devclass_list_short(void);
void            print_devclass_list(void);

#else
/* Make the compiler ignore the function calls */
#define PDEBUG(a)                       /* nop */
#define DEVICENAME(d)                   /* nop */
#define DRIVERNAME(d)                   /* nop */
#define DEVCLANAME(d)                   /* nop */

#define print_device_short(d,i)         /* nop */
#define print_device(d,i)               /* nop */
#define print_device_tree_short(d,i)    /* nop */
#define print_device_tree(d,i)          /* nop */
#define print_driver_short(d,i)         /* nop */
#define print_driver(d,i)               /* nop */
#define print_driver_list(d,i)          /* nop */
#define print_devclass_short(d,i)       /* nop */
#define print_devclass(d,i)             /* nop */
#define print_devclass_list_short()     /* nop */
#define print_devclass_list()           /* nop */
#endif

/*
 * dev sysctl tree
 */

enum {
        DEVCLASS_SYSCTL_PARENT,
};

static int
devclass_sysctl_handler(SYSCTL_HANDLER_ARGS)
{
        devclass_t dc = (devclass_t)arg1;
        const char *value;

        switch (arg2) {
        case DEVCLASS_SYSCTL_PARENT:
                value = dc->parent ? dc->parent->name : "";
                break;
        default:
                return (EINVAL);
        }
        return (SYSCTL_OUT(req, value, strlen(value)));
}

static void
devclass_sysctl_init(devclass_t dc)
{

        if (dc->sysctl_tree != NULL)
                return;
        sysctl_ctx_init(&dc->sysctl_ctx);
        dc->sysctl_tree = SYSCTL_ADD_NODE(&dc->sysctl_ctx,
            SYSCTL_STATIC_CHILDREN(_dev), OID_AUTO, dc->name,
            CTLFLAG_RD, NULL, "");
        SYSCTL_ADD_PROC(&dc->sysctl_ctx, SYSCTL_CHILDREN(dc->sysctl_tree),
            OID_AUTO, "%parent", CTLTYPE_STRING | CTLFLAG_RD,
            dc, DEVCLASS_SYSCTL_PARENT, devclass_sysctl_handler, "A",
            "parent class");
}

enum {
        DEVICE_SYSCTL_DESC,
        DEVICE_SYSCTL_DRIVER,
        DEVICE_SYSCTL_LOCATION,
        DEVICE_SYSCTL_PNPINFO,
        DEVICE_SYSCTL_PARENT,
};

static int
device_sysctl_handler(SYSCTL_HANDLER_ARGS)
{
        device_t dev = (device_t)arg1;
        const char *value;
        char *buf;
        int error;

        buf = NULL;
        switch (arg2) {
        case DEVICE_SYSCTL_DESC:
                value = dev->desc ? dev->desc : "";
                break;
        case DEVICE_SYSCTL_DRIVER:
                value = dev->driver ? dev->driver->name : "";
                break;
        case DEVICE_SYSCTL_LOCATION:
                value = buf = kmalloc(1024, M_BUS, M_WAITOK | M_ZERO);
                bus_child_location_str(dev, buf, 1024);
                break;
        case DEVICE_SYSCTL_PNPINFO:
                value = buf = kmalloc(1024, M_BUS, M_WAITOK | M_ZERO);
                bus_child_pnpinfo_str(dev, buf, 1024);
                break;
        case DEVICE_SYSCTL_PARENT:
                value = dev->parent ? dev->parent->nameunit : "";
                break;
        default:
                return (EINVAL);
        }
        error = SYSCTL_OUT(req, value, strlen(value));
        if (buf != NULL)
                kfree(buf, M_BUS);
        return (error);
}

static void
device_sysctl_init(device_t dev)
{
        devclass_t dc = dev->devclass;

        if (dev->sysctl_tree != NULL)
                return;
        devclass_sysctl_init(dc);
        sysctl_ctx_init(&dev->sysctl_ctx);
        dev->sysctl_tree = SYSCTL_ADD_NODE(&dev->sysctl_ctx,
            SYSCTL_CHILDREN(dc->sysctl_tree), OID_AUTO,
            dev->nameunit + strlen(dc->name),
            CTLFLAG_RD, NULL, "");
        SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
            OID_AUTO, "%desc", CTLTYPE_STRING | CTLFLAG_RD,
            dev, DEVICE_SYSCTL_DESC, device_sysctl_handler, "A",
            "device description");
        SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
            OID_AUTO, "%driver", CTLTYPE_STRING | CTLFLAG_RD,
            dev, DEVICE_SYSCTL_DRIVER, device_sysctl_handler, "A",
            "device driver name");
        SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
            OID_AUTO, "%location", CTLTYPE_STRING | CTLFLAG_RD,
            dev, DEVICE_SYSCTL_LOCATION, device_sysctl_handler, "A",
            "device location relative to parent");
        SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
            OID_AUTO, "%pnpinfo", CTLTYPE_STRING | CTLFLAG_RD,
            dev, DEVICE_SYSCTL_PNPINFO, device_sysctl_handler, "A",
            "device identification");
        SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
            OID_AUTO, "%parent", CTLTYPE_STRING | CTLFLAG_RD,
            dev, DEVICE_SYSCTL_PARENT, device_sysctl_handler, "A",
            "parent device");
}

static void
device_sysctl_update(device_t dev)
{
        devclass_t dc = dev->devclass;

        if (dev->sysctl_tree == NULL)
                return;
        sysctl_rename_oid(dev->sysctl_tree, dev->nameunit + strlen(dc->name));
}

static void
device_sysctl_fini(device_t dev)
{
        if (dev->sysctl_tree == NULL)
                return;
        sysctl_ctx_free(&dev->sysctl_ctx);
        dev->sysctl_tree = NULL;
}

static void     device_attach_async(device_t dev);
static void     device_attach_thread(void *arg);
static int      device_doattach(device_t dev);

static int do_async_attach = 0;
static int numasyncthreads;
TUNABLE_INT("kern.do_async_attach", &do_async_attach);

/*
 * /dev/devctl implementation
 */

/*
 * This design allows only one reader for /dev/devctl.  This is not desirable
 * in the long run, but will get a lot of hair out of this implementation.
 * Maybe we should make this device a clonable device.
 *
 * Also note: we specifically do not attach a device to the device_t tree
 * to avoid potential chicken and egg problems.  One could argue that all
 * of this belongs to the root node.  One could also further argue that the
 * sysctl interface that we have not might more properly be an ioctl
 * interface, but at this stage of the game, I'm not inclined to rock that
 * boat.
 *
 * I'm also not sure that the SIGIO support is done correctly or not, as
 * I copied it from a driver that had SIGIO support that likely hasn't been
 * tested since 3.4 or 2.2.8!
 */

static int sysctl_devctl_disable(SYSCTL_HANDLER_ARGS);
static int devctl_disable = 0;
TUNABLE_INT("hw.bus.devctl_disable", &devctl_disable);
SYSCTL_PROC(_hw_bus, OID_AUTO, devctl_disable, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
    sysctl_devctl_disable, "I", "devctl disable");

static d_open_t         devopen;
static d_close_t        devclose;
static d_read_t         devread;
static d_ioctl_t        devioctl;
static d_kqfilter_t     devkqfilter;

static struct dev_ops devctl_ops = {
        { "devctl", 0, 0 },
        .d_open =       devopen,
        .d_close =      devclose,
        .d_read =       devread,
        .d_ioctl =      devioctl,
        .d_kqfilter =   devkqfilter
};

struct dev_event_info
{
        char *dei_data;
        TAILQ_ENTRY(dev_event_info) dei_link;
};

TAILQ_HEAD(devq, dev_event_info);

static struct dev_softc
{
        int     inuse;
        struct lock lock;
        struct kqinfo kq;
        struct devq devq;
        struct proc *async_proc;
} devsoftc;

static void
devinit(void)
{
        make_dev(&devctl_ops, 0, UID_ROOT, GID_WHEEL, 0600, "devctl");
        lockinit(&devsoftc.lock, "dev mtx", 0, 0);
        TAILQ_INIT(&devsoftc.devq);
}

static int
devopen(struct dev_open_args *ap)
{
        if (devsoftc.inuse)
                return (EBUSY);
        /* move to init */
        devsoftc.inuse = 1;
        devsoftc.async_proc = NULL;
        return (0);
}

static int
devclose(struct dev_close_args *ap)
{
        devsoftc.inuse = 0;
        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        wakeup(&devsoftc);
        lockmgr(&devsoftc.lock, LK_RELEASE);

        return (0);
}

/*
 * The read channel for this device is used to report changes to
 * userland in realtime.  We are required to free the data as well as
 * the n1 object because we allocate them separately.  Also note that
 * we return one record at a time.  If you try to read this device a
 * character at a time, you will lose the rest of the data.  Listening
 * programs are expected to cope.
 */
static int
devread(struct dev_read_args *ap)
{
        struct uio *uio = ap->a_uio;
        struct dev_event_info *n1;
        int rv;

        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        while (TAILQ_EMPTY(&devsoftc.devq)) {
                if (ap->a_ioflag & IO_NDELAY) {
                        lockmgr(&devsoftc.lock, LK_RELEASE);
                        return (EAGAIN);
                }
                tsleep_interlock(&devsoftc, PCATCH);
                lockmgr(&devsoftc.lock, LK_RELEASE);
                rv = tsleep(&devsoftc, PCATCH | PINTERLOCKED, "devctl", 0);
                lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
                if (rv) {
                        /*
                         * Need to translate ERESTART to EINTR here? -- jake
                         */
                        lockmgr(&devsoftc.lock, LK_RELEASE);
                        return (rv);
                }
        }
        n1 = TAILQ_FIRST(&devsoftc.devq);
        TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
        lockmgr(&devsoftc.lock, LK_RELEASE);
        rv = uiomove(n1->dei_data, strlen(n1->dei_data), uio);
        kfree(n1->dei_data, M_BUS);
        kfree(n1, M_BUS);
        return (rv);
}

static  int
devioctl(struct dev_ioctl_args *ap)
{
        switch (ap->a_cmd) {

        case FIONBIO:
                return (0);
        case FIOASYNC:
                if (*(int*)ap->a_data)
                        devsoftc.async_proc = curproc;
                else
                        devsoftc.async_proc = NULL;
                return (0);

                /* (un)Support for other fcntl() calls. */
        case FIOCLEX:
        case FIONCLEX:
        case FIONREAD:
        case FIOSETOWN:
        case FIOGETOWN:
        default:
                break;
        }
        return (ENOTTY);
}

static void dev_filter_detach(struct knote *);
static int dev_filter_read(struct knote *, long);

static struct filterops dev_filtops =
        { FILTEROP_ISFD, NULL, dev_filter_detach, dev_filter_read };

static int
devkqfilter(struct dev_kqfilter_args *ap)
{
        struct knote *kn = ap->a_kn;
        struct klist *klist;

        ap->a_result = 0;
        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &dev_filtops;
                break;
        default:
                ap->a_result = EOPNOTSUPP;
                lockmgr(&devsoftc.lock, LK_RELEASE);
                return (0);
        }

        klist = &devsoftc.kq.ki_note;
        knote_insert(klist, kn);

        lockmgr(&devsoftc.lock, LK_RELEASE);

        return (0);
}

static void
dev_filter_detach(struct knote *kn)
{
        struct klist *klist;

        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        klist = &devsoftc.kq.ki_note;
        knote_remove(klist, kn);
        lockmgr(&devsoftc.lock, LK_RELEASE);
}

static int
dev_filter_read(struct knote *kn, long hint)
{
        int ready = 0;

        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        if (!TAILQ_EMPTY(&devsoftc.devq))
                ready = 1;
        lockmgr(&devsoftc.lock, LK_RELEASE);

        return (ready);
}


/**
 * @brief Return whether the userland process is running
 */
boolean_t
devctl_process_running(void)
{
        return (devsoftc.inuse == 1);
}

/**
 * @brief Queue data to be read from the devctl device
 *
 * Generic interface to queue data to the devctl device.  It is
 * assumed that @p data is properly formatted.  It is further assumed
 * that @p data is allocated using the M_BUS malloc type.
 */
void
devctl_queue_data(char *data)
{
        struct dev_event_info *n1 = NULL;
        struct proc *p;

        n1 = kmalloc(sizeof(*n1), M_BUS, M_NOWAIT);
        if (n1 == NULL)
                return;
        n1->dei_data = data;
        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        TAILQ_INSERT_TAIL(&devsoftc.devq, n1, dei_link);
        wakeup(&devsoftc);
        lockmgr(&devsoftc.lock, LK_RELEASE);
        KNOTE(&devsoftc.kq.ki_note, 0);
        p = devsoftc.async_proc;
        if (p != NULL)
                ksignal(p, SIGIO);
}

/**
 * @brief Send a 'notification' to userland, using standard ways
 */
void
devctl_notify(const char *system, const char *subsystem, const char *type,
    const char *data)
{
        int len = 0;
        char *msg;

        if (system == NULL)
                return;         /* BOGUS!  Must specify system. */
        if (subsystem == NULL)
                return;         /* BOGUS!  Must specify subsystem. */
        if (type == NULL)
                return;         /* BOGUS!  Must specify type. */
        len += strlen(" system=") + strlen(system);
        len += strlen(" subsystem=") + strlen(subsystem);
        len += strlen(" type=") + strlen(type);
        /* add in the data message plus newline. */
        if (data != NULL)
                len += strlen(data);
        len += 3;       /* '!', '\n', and NUL */
        msg = kmalloc(len, M_BUS, M_NOWAIT);
        if (msg == NULL)
                return;         /* Drop it on the floor */
        if (data != NULL)
                ksnprintf(msg, len, "!system=%s subsystem=%s type=%s %s\n",
                    system, subsystem, type, data);
        else
                ksnprintf(msg, len, "!system=%s subsystem=%s type=%s\n",
                    system, subsystem, type);
        devctl_queue_data(msg);
}

/*
 * Common routine that tries to make sending messages as easy as possible.
 * We allocate memory for the data, copy strings into that, but do not
 * free it unless there's an error.  The dequeue part of the driver should
 * free the data.  We don't send data when the device is disabled.  We do
 * send data, even when we have no listeners, because we wish to avoid
 * races relating to startup and restart of listening applications.
 *
 * devaddq is designed to string together the type of event, with the
 * object of that event, plus the plug and play info and location info
 * for that event.  This is likely most useful for devices, but less
 * useful for other consumers of this interface.  Those should use
 * the devctl_queue_data() interface instead.
 */
static void
devaddq(const char *type, const char *what, device_t dev)
{
        char *data = NULL;
        char *loc = NULL;
        char *pnp = NULL;
        const char *parstr;

        if (devctl_disable)
                return;
        data = kmalloc(1024, M_BUS, M_NOWAIT);
        if (data == NULL)
                goto bad;

        /* get the bus specific location of this device */
        loc = kmalloc(1024, M_BUS, M_NOWAIT);
        if (loc == NULL)
                goto bad;
        *loc = '\0';
        bus_child_location_str(dev, loc, 1024);

        /* Get the bus specific pnp info of this device */
        pnp = kmalloc(1024, M_BUS, M_NOWAIT);
        if (pnp == NULL)
                goto bad;
        *pnp = '\0';
        bus_child_pnpinfo_str(dev, pnp, 1024);

        /* Get the parent of this device, or / if high enough in the tree. */
        if (device_get_parent(dev) == NULL)
                parstr = ".";   /* Or '/' ? */
        else
                parstr = device_get_nameunit(device_get_parent(dev));
        /* String it all together. */
        ksnprintf(data, 1024, "%s%s at %s %s on %s\n", type, what, loc, pnp,
          parstr);
        kfree(loc, M_BUS);
        kfree(pnp, M_BUS);
        devctl_queue_data(data);
        return;
bad:
        kfree(pnp, M_BUS);
        kfree(loc, M_BUS);
        kfree(data, M_BUS);
        return;
}

/*
 * A device was added to the tree.  We are called just after it successfully
 * attaches (that is, probe and attach success for this device).  No call
 * is made if a device is merely parented into the tree.  See devnomatch
 * if probe fails.  If attach fails, no notification is sent (but maybe
 * we should have a different message for this).
 */
static void
devadded(device_t dev)
{
        char *pnp = NULL;
        char *tmp = NULL;

        pnp = kmalloc(1024, M_BUS, M_NOWAIT);
        if (pnp == NULL)
                goto fail;
        tmp = kmalloc(1024, M_BUS, M_NOWAIT);
        if (tmp == NULL)
                goto fail;
        *pnp = '\0';
        bus_child_pnpinfo_str(dev, pnp, 1024);
        ksnprintf(tmp, 1024, "%s %s", device_get_nameunit(dev), pnp);
        devaddq("+", tmp, dev);
fail:
        if (pnp != NULL)
                kfree(pnp, M_BUS);
        if (tmp != NULL)
                kfree(tmp, M_BUS);
        return;
}

/*
 * A device was removed from the tree.  We are called just before this
 * happens.
 */
static void
devremoved(device_t dev)
{
        char *pnp = NULL;
        char *tmp = NULL;

        pnp = kmalloc(1024, M_BUS, M_NOWAIT);
        if (pnp == NULL)
                goto fail;
        tmp = kmalloc(1024, M_BUS, M_NOWAIT);
        if (tmp == NULL)
                goto fail;
        *pnp = '\0';
        bus_child_pnpinfo_str(dev, pnp, 1024);
        ksnprintf(tmp, 1024, "%s %s", device_get_nameunit(dev), pnp);
        devaddq("-", tmp, dev);
fail:
        if (pnp != NULL)
                kfree(pnp, M_BUS);
        if (tmp != NULL)
                kfree(tmp, M_BUS);
        return;
}

/*
 * Called when there's no match for this device.  This is only called
 * the first time that no match happens, so we don't keep getitng this
 * message.  Should that prove to be undesirable, we can change it.
 * This is called when all drivers that can attach to a given bus
 * decline to accept this device.  Other errrors may not be detected.
 */
static void
devnomatch(device_t dev)
{
        devaddq("?", "", dev);
}

static int
sysctl_devctl_disable(SYSCTL_HANDLER_ARGS)
{
        struct dev_event_info *n1;
        int dis, error;

        dis = devctl_disable;
        error = sysctl_handle_int(oidp, &dis, 0, req);
        if (error || !req->newptr)
                return (error);
        lockmgr(&devsoftc.lock, LK_EXCLUSIVE);
        devctl_disable = dis;
        if (dis) {
                while (!TAILQ_EMPTY(&devsoftc.devq)) {
                        n1 = TAILQ_FIRST(&devsoftc.devq);
                        TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
                        kfree(n1->dei_data, M_BUS);
                        kfree(n1, M_BUS);
                }
        }
        lockmgr(&devsoftc.lock, LK_RELEASE);
        return (0);
}

/* End of /dev/devctl code */

TAILQ_HEAD(,device)     bus_data_devices;
static int bus_data_generation = 1;

kobj_method_t null_methods[] = {
        { 0, 0 }
};

DEFINE_CLASS(null, null_methods, 0);

/*
 * Devclass implementation
 */

static devclass_list_t devclasses = TAILQ_HEAD_INITIALIZER(devclasses);

static devclass_t
devclass_find_internal(const char *classname, const char *parentname,
                       int create)
{
        devclass_t dc;

        PDEBUG(("looking for %s", classname));
        if (classname == NULL)
                return(NULL);

        TAILQ_FOREACH(dc, &devclasses, link)
                if (!strcmp(dc->name, classname))
                        break;

        if (create && !dc) {
                PDEBUG(("creating %s", classname));
                dc = kmalloc(sizeof(struct devclass) + strlen(classname) + 1,
                            M_BUS, M_INTWAIT | M_ZERO);
                dc->parent = NULL;
                dc->name = (char*) (dc + 1);
                strcpy(dc->name, classname);
                dc->devices = NULL;
                dc->maxunit = 0;
                TAILQ_INIT(&dc->drivers);
                TAILQ_INSERT_TAIL(&devclasses, dc, link);

                bus_data_generation_update();

        }

        /*
         * If a parent class is specified, then set that as our parent so
         * that this devclass will support drivers for the parent class as
         * well.  If the parent class has the same name don't do this though
         * as it creates a cycle that can trigger an infinite loop in
         * device_probe_child() if a device exists for which there is no
         * suitable driver.
         */
        if (parentname && dc && !dc->parent &&
            strcmp(classname, parentname) != 0)
                dc->parent = devclass_find_internal(parentname, NULL, FALSE);

        return(dc);
}

devclass_t
devclass_create(const char *classname)
{
        return(devclass_find_internal(classname, NULL, TRUE));
}

devclass_t
devclass_find(const char *classname)
{
        return(devclass_find_internal(classname, NULL, FALSE));
}

device_t
devclass_find_unit(const char *classname, int unit)
{
        devclass_t dc;

        if ((dc = devclass_find(classname)) != NULL)
            return(devclass_get_device(dc, unit));
        return (NULL);
}

int
devclass_add_driver(devclass_t dc, driver_t *driver)
{
        driverlink_t dl;
        device_t dev;
        int i;

        PDEBUG(("%s", DRIVERNAME(driver)));

        dl = kmalloc(sizeof *dl, M_BUS, M_INTWAIT | M_ZERO);

        /*
         * Compile the driver's methods. Also increase the reference count
         * so that the class doesn't get freed when the last instance
         * goes. This means we can safely use static methods and avoids a
         * double-free in devclass_delete_driver.
         */
        kobj_class_instantiate(driver);

        /*
         * Make sure the devclass which the driver is implementing exists.
         */
        devclass_find_internal(driver->name, NULL, TRUE);

        dl->driver = driver;
        TAILQ_INSERT_TAIL(&dc->drivers, dl, link);

        /*
         * Call BUS_DRIVER_ADDED for any existing busses in this class,
         * but only if the bus has already been attached (otherwise we
         * might probe too early).
         *
         * This is what will cause a newly loaded module to be associated
         * with hardware.  bus_generic_driver_added() is typically what ends
         * up being called.
         */
        for (i = 0; i < dc->maxunit; i++) {
                if ((dev = dc->devices[i]) != NULL) {
                        if (dev->state >= DS_ATTACHED)
                                BUS_DRIVER_ADDED(dev, driver);
                }
        }

        bus_data_generation_update();
        return(0);
}

int
devclass_delete_driver(devclass_t busclass, driver_t *driver)
{
        devclass_t dc = devclass_find(driver->name);
        driverlink_t dl;
        device_t dev;
        int i;
        int error;

        PDEBUG(("%s from devclass %s", driver->name, DEVCLANAME(busclass)));

        if (!dc)
                return(0);

        /*
         * Find the link structure in the bus' list of drivers.
         */
        TAILQ_FOREACH(dl, &busclass->drivers, link)
                if (dl->driver == driver)
                        break;

        if (!dl) {
                PDEBUG(("%s not found in %s list", driver->name, busclass->name));
                return(ENOENT);
        }

        /*
         * Disassociate from any devices.  We iterate through all the
         * devices in the devclass of the driver and detach any which are
         * using the driver and which have a parent in the devclass which
         * we are deleting from.
         *
         * Note that since a driver can be in multiple devclasses, we
         * should not detach devices which are not children of devices in
         * the affected devclass.
         */
        for (i = 0; i < dc->maxunit; i++)
                if (dc->devices[i]) {
                        dev = dc->devices[i];
                        if (dev->driver == driver && dev->parent &&
                            dev->parent->devclass == busclass) {
                                if ((error = device_detach(dev)) != 0)
                                        return(error);
                                device_set_driver(dev, NULL);
                        }
                }

        TAILQ_REMOVE(&busclass->drivers, dl, link);
        kfree(dl, M_BUS);

        kobj_class_uninstantiate(driver);

        bus_data_generation_update();
        return(0);
}

static driverlink_t
devclass_find_driver_internal(devclass_t dc, const char *classname)
{
        driverlink_t dl;

        PDEBUG(("%s in devclass %s", classname, DEVCLANAME(dc)));

        TAILQ_FOREACH(dl, &dc->drivers, link)
                if (!strcmp(dl->driver->name, classname))
                        return(dl);

        PDEBUG(("not found"));
        return(NULL);
}

kobj_class_t
devclass_find_driver(devclass_t dc, const char *classname)
{
        driverlink_t dl;

        dl = devclass_find_driver_internal(dc, classname);
        if (dl)
                return(dl->driver);
        else
                return(NULL);
}

const char *
devclass_get_name(devclass_t dc)
{
        return(dc->name);
}

device_t
devclass_get_device(devclass_t dc, int unit)
{
        if (dc == NULL || unit < 0 || unit >= dc->maxunit)
                return(NULL);
        return(dc->devices[unit]);
}

void *
devclass_get_softc(devclass_t dc, int unit)
{
        device_t dev;

        dev = devclass_get_device(dc, unit);
        if (!dev)
                return(NULL);

        return(device_get_softc(dev));
}

int
devclass_get_devices(devclass_t dc, device_t **devlistp, int *devcountp)
{
        int i;
        int count;
        device_t *list;
    
        count = 0;
        for (i = 0; i < dc->maxunit; i++)
                if (dc->devices[i])
                        count++;

        list = kmalloc(count * sizeof(device_t), M_TEMP, M_INTWAIT | M_ZERO);

        count = 0;
        for (i = 0; i < dc->maxunit; i++)
                if (dc->devices[i]) {
                        list[count] = dc->devices[i];
                        count++;
                }

        *devlistp = list;
        *devcountp = count;

        return(0);
}

/**
 * @brief Get a list of drivers in the devclass
 *
 * An array containing a list of pointers to all the drivers in the
 * given devclass is allocated and returned in @p *listp.  The number
 * of drivers in the array is returned in @p *countp. The caller should
 * free the array using @c free(p, M_TEMP).
 *
 * @param dc            the devclass to examine
 * @param listp         gives location for array pointer return value
 * @param countp        gives location for number of array elements
 *                      return value
 *
 * @retval 0            success
 * @retval ENOMEM       the array allocation failed
 */
int
devclass_get_drivers(devclass_t dc, driver_t ***listp, int *countp)
{
        driverlink_t dl;
        driver_t **list;
        int count;

        count = 0;
        TAILQ_FOREACH(dl, &dc->drivers, link)
                count++;
        list = kmalloc(count * sizeof(driver_t *), M_TEMP, M_NOWAIT);
        if (list == NULL)
                return (ENOMEM);

        count = 0;
        TAILQ_FOREACH(dl, &dc->drivers, link) {
                list[count] = dl->driver;
                count++;
        }
        *listp = list;
        *countp = count;

        return (0);
}

/**
 * @brief Get the number of devices in a devclass
 *
 * @param dc            the devclass to examine
 */
int
devclass_get_count(devclass_t dc)
{
        int count, i;

        count = 0;
        for (i = 0; i < dc->maxunit; i++)
                if (dc->devices[i])
                        count++;
        return (count);
}

int
devclass_get_maxunit(devclass_t dc)
{
        return(dc->maxunit);
}

void
devclass_set_parent(devclass_t dc, devclass_t pdc)
{
        dc->parent = pdc;
}

devclass_t
devclass_get_parent(devclass_t dc)
{
        return(dc->parent);
}

static int
devclass_alloc_unit(devclass_t dc, int *unitp)
{
        int unit = *unitp;

        PDEBUG(("unit %d in devclass %s", unit, DEVCLANAME(dc)));

        /* If we have been given a wired unit number, check for existing device */
        if (unit != -1) {
                if (unit >= 0 && unit < dc->maxunit &&
                    dc->devices[unit] != NULL) {
                        if (bootverbose)
                                kprintf("%s-: %s%d exists, using next available unit number\n",
                                       dc->name, dc->name, unit);
                        /* find the next available slot */
                        while (++unit < dc->maxunit && dc->devices[unit] != NULL)
                                ;
                }
        } else {
                /* Unwired device, find the next available slot for it */
                unit = 0;
                while (unit < dc->maxunit && dc->devices[unit] != NULL)
                        unit++;
        }

        /*
         * We've selected a unit beyond the length of the table, so let's
         * extend the table to make room for all units up to and including
         * this one.
         */
        if (unit >= dc->maxunit) {
                device_t *newlist;
                int newsize;

                newsize = (unit + 1);
                newlist = kmalloc(sizeof(device_t) * newsize, M_BUS,
                                 M_INTWAIT | M_ZERO);
                if (newlist == NULL)
                        return(ENOMEM);
                bcopy(dc->devices, newlist, sizeof(device_t) * dc->maxunit);
                if (dc->devices)
                        kfree(dc->devices, M_BUS);
                dc->devices = newlist;
                dc->maxunit = newsize;
        }
        PDEBUG(("now: unit %d in devclass %s", unit, DEVCLANAME(dc)));

        *unitp = unit;
        return(0);
}

static int
devclass_add_device(devclass_t dc, device_t dev)
{
        int buflen, error;

        PDEBUG(("%s in devclass %s", DEVICENAME(dev), DEVCLANAME(dc)));

        buflen = strlen(dc->name) + 5;
        dev->nameunit = kmalloc(buflen, M_BUS, M_INTWAIT | M_ZERO);
        if (dev->nameunit == NULL)
                return(ENOMEM);

        if ((error = devclass_alloc_unit(dc, &dev->unit)) != 0) {
                kfree(dev->nameunit, M_BUS);
                dev->nameunit = NULL;
                return(error);
        }
        dc->devices[dev->unit] = dev;
        dev->devclass = dc;
        ksnprintf(dev->nameunit, buflen, "%s%d", dc->name, dev->unit);

        return(0);
}

static int
devclass_delete_device(devclass_t dc, device_t dev)
{
        if (!dc || !dev)
                return(0);

        PDEBUG(("%s in devclass %s", DEVICENAME(dev), DEVCLANAME(dc)));

        if (dev->devclass != dc || dc->devices[dev->unit] != dev)
                panic("devclass_delete_device: inconsistent device class");
        dc->devices[dev->unit] = NULL;
        if (dev->flags & DF_WILDCARD)
                dev->unit = -1;
        dev->devclass = NULL;
        kfree(dev->nameunit, M_BUS);
        dev->nameunit = NULL;

        return(0);
}

static device_t
make_device(device_t parent, const char *name, int unit)
{
        device_t dev;
        devclass_t dc;

        PDEBUG(("%s at %s as unit %d", name, DEVICENAME(parent), unit));

        if (name != NULL) {
                dc = devclass_find_internal(name, NULL, TRUE);
                if (!dc) {
                        kprintf("make_device: can't find device class %s\n", name);
                        return(NULL);
                }
        } else
                dc = NULL;

        dev = kmalloc(sizeof(struct device), M_BUS, M_INTWAIT | M_ZERO);
        if (!dev)
                return(0);

        dev->parent = parent;
        TAILQ_INIT(&dev->children);
        kobj_init((kobj_t) dev, &null_class);
        dev->driver = NULL;
        dev->devclass = NULL;
        dev->unit = unit;
        dev->nameunit = NULL;
        dev->desc = NULL;
        dev->busy = 0;
        dev->devflags = 0;
        dev->flags = DF_ENABLED;
        dev->order = 0;
        if (unit == -1)
                dev->flags |= DF_WILDCARD;
        if (name) {
                dev->flags |= DF_FIXEDCLASS;
                if (devclass_add_device(dc, dev) != 0) {
                        kobj_delete((kobj_t)dev, M_BUS);
                        return(NULL);
                }
        }
        dev->ivars = NULL;
        dev->softc = NULL;

        dev->state = DS_NOTPRESENT;

        TAILQ_INSERT_TAIL(&bus_data_devices, dev, devlink);
        bus_data_generation_update();

        return(dev);
}

static int
device_print_child(device_t dev, device_t child)
{
        int retval = 0;

        if (device_is_alive(child))
                retval += BUS_PRINT_CHILD(dev, child);
        else
                retval += device_printf(child, " not found\n");

        return(retval);
}

device_t
device_add_child(device_t dev, const char *name, int unit)
{
        return device_add_child_ordered(dev, 0, name, unit);
}

device_t
device_add_child_ordered(device_t dev, int order, const char *name, int unit)
{
        device_t child;
        device_t place;

        PDEBUG(("%s at %s with order %d as unit %d", name, DEVICENAME(dev),
                order, unit));

        child = make_device(dev, name, unit);
        if (child == NULL)
                return child;
        child->order = order;

        TAILQ_FOREACH(place, &dev->children, link)
                if (place->order > order)
                        break;

        if (place) {
                /*
                 * The device 'place' is the first device whose order is
                 * greater than the new child.
                 */
                TAILQ_INSERT_BEFORE(place, child, link);
        } else {
                /*
                 * The new child's order is greater or equal to the order of
                 * any existing device. Add the child to the tail of the list.
                 */
                TAILQ_INSERT_TAIL(&dev->children, child, link);
        }

        bus_data_generation_update();
        return(child);
}

int
device_delete_child(device_t dev, device_t child)
{
        int error;
        device_t grandchild;

        PDEBUG(("%s from %s", DEVICENAME(child), DEVICENAME(dev)));

        /* remove children first */
        while ( (grandchild = TAILQ_FIRST(&child->children)) ) {
                error = device_delete_child(child, grandchild);
                if (error)
                        return(error);
        }

        if ((error = device_detach(child)) != 0)
                return(error);
        if (child->devclass)
                devclass_delete_device(child->devclass, child);
        TAILQ_REMOVE(&dev->children, child, link);
        TAILQ_REMOVE(&bus_data_devices, child, devlink);
        kobj_delete((kobj_t)child, M_BUS);

        bus_data_generation_update();
        return(0);
}

/**
 * @brief Delete all children devices of the given device, if any.
 *
 * This function deletes all children devices of the given device, if
 * any, using the device_delete_child() function for each device it
 * finds. If a child device cannot be deleted, this function will
 * return an error code.
 * 
 * @param dev           the parent device
 *
 * @retval 0            success
 * @retval non-zero     a device would not detach
 */
int
device_delete_children(device_t dev)
{
        device_t child;
        int error;

        PDEBUG(("Deleting all children of %s", DEVICENAME(dev)));

        error = 0;

        while ((child = TAILQ_FIRST(&dev->children)) != NULL) {
                error = device_delete_child(dev, child);
                if (error) {
                        PDEBUG(("Failed deleting %s", DEVICENAME(child)));
                        break;
                }
        }
        return (error);
}

/**
 * @brief Find a device given a unit number
 *
 * This is similar to devclass_get_devices() but only searches for
 * devices which have @p dev as a parent.
 *
 * @param dev           the parent device to search
 * @param unit          the unit number to search for.  If the unit is -1,
 *                      return the first child of @p dev which has name
 *                      @p classname (that is, the one with the lowest unit.)
 *
 * @returns             the device with the given unit number or @c
 *                      NULL if there is no such device
 */
device_t
device_find_child(device_t dev, const char *classname, int unit)
{
        devclass_t dc;
        device_t child;

        dc = devclass_find(classname);
        if (!dc)
                return(NULL);

        if (unit != -1) {
                child = devclass_get_device(dc, unit);
                if (child && child->parent == dev)
                        return (child);
        } else {
                for (unit = 0; unit < devclass_get_maxunit(dc); unit++) {
                        child = devclass_get_device(dc, unit);
                        if (child && child->parent == dev)
                                return (child);
                }
        }
        return(NULL);
}

static driverlink_t
first_matching_driver(devclass_t dc, device_t dev)
{
        if (dev->devclass)
                return(devclass_find_driver_internal(dc, dev->devclass->name));
        else
                return(TAILQ_FIRST(&dc->drivers));
}

static driverlink_t
next_matching_driver(devclass_t dc, device_t dev, driverlink_t last)
{
        if (dev->devclass) {
                driverlink_t dl;
                for (dl = TAILQ_NEXT(last, link); dl; dl = TAILQ_NEXT(dl, link))
                        if (!strcmp(dev->devclass->name, dl->driver->name))
                                return(dl);
                return(NULL);
        } else
                return(TAILQ_NEXT(last, link));
}

int
device_probe_child(device_t dev, device_t child)
{
        devclass_t dc;
        driverlink_t best = NULL;
        driverlink_t dl;
        int result, pri = 0;
        int hasclass = (child->devclass != NULL);

        dc = dev->devclass;
        if (!dc)
                panic("device_probe_child: parent device has no devclass");

        if (child->state == DS_ALIVE)
                return(0);

        for (; dc; dc = dc->parent) {
                for (dl = first_matching_driver(dc, child); dl;
                     dl = next_matching_driver(dc, child, dl)) {
                        PDEBUG(("Trying %s", DRIVERNAME(dl->driver)));
                        device_set_driver(child, dl->driver);
                        if (!hasclass)
                                device_set_devclass(child, dl->driver->name);
                        result = DEVICE_PROBE(child);
                        if (!hasclass)
                                device_set_devclass(child, 0);

                        /*
                         * If the driver returns SUCCESS, there can be
                         * no higher match for this device.
                         */
                        if (result == 0) {
                                best = dl;
                                pri = 0;
                                break;
                        }

                        /*
                         * The driver returned an error so it
                         * certainly doesn't match.
                         */
                        if (result > 0) {
                                device_set_driver(child, NULL);
                                continue;
                        }

                        /*
                         * A priority lower than SUCCESS, remember the
                         * best matching driver. Initialise the value
                         * of pri for the first match.
                         */
                        if (best == NULL || result > pri) {
                                best = dl;
                                pri = result;
                                continue;
                        }
                }
                /*
                 * If we have unambiguous match in this devclass,
                 * don't look in the parent.
                 */
                if (best && pri == 0)
                        break;
        }

        /*
         * If we found a driver, change state and initialise the devclass.
         */
        if (best) {
                if (!child->devclass)
                        device_set_devclass(child, best->driver->name);
                device_set_driver(child, best->driver);
                if (pri < 0) {
                        /*
                         * A bit bogus. Call the probe method again to make
                         * sure that we have the right description.
                         */
                        DEVICE_PROBE(child);
                }

                bus_data_generation_update();
                child->state = DS_ALIVE;
                return(0);
        }

        return(ENXIO);
}

device_t
device_get_parent(device_t dev)
{
        return dev->parent;
}

int
device_get_children(device_t dev, device_t **devlistp, int *devcountp)
{
        int count;
        device_t child;
        device_t *list;
    
        count = 0;
        TAILQ_FOREACH(child, &dev->children, link)
                count++;

        list = kmalloc(count * sizeof(device_t), M_TEMP, M_INTWAIT | M_ZERO);

        count = 0;
        TAILQ_FOREACH(child, &dev->children, link) {
                list[count] = child;
                count++;
        }

        *devlistp = list;
        *devcountp = count;

        return(0);
}

driver_t *
device_get_driver(device_t dev)
{
        return(dev->driver);
}

devclass_t
device_get_devclass(device_t dev)
{
        return(dev->devclass);
}

const char *
device_get_name(device_t dev)
{
        if (dev->devclass)
                return devclass_get_name(dev->devclass);
        return(NULL);
}

const char *
device_get_nameunit(device_t dev)
{
        return(dev->nameunit);
}

int
device_get_unit(device_t dev)
{
        return(dev->unit);
}

const char *
device_get_desc(device_t dev)
{
        return(dev->desc);
}

uint32_t
device_get_flags(device_t dev)
{
        return(dev->devflags);
}

struct sysctl_ctx_list *
device_get_sysctl_ctx(device_t dev)
{
        return (&dev->sysctl_ctx);
}

struct sysctl_oid *
device_get_sysctl_tree(device_t dev)
{
        return (dev->sysctl_tree);
}

int
device_print_prettyname(device_t dev)
{
        const char *name = device_get_name(dev);

        if (name == NULL)
                return kprintf("unknown: ");
        else
                return kprintf("%s%d: ", name, device_get_unit(dev));
}

int
device_printf(device_t dev, const char * fmt, ...)
{
        __va_list ap;
        int retval;

        retval = device_print_prettyname(dev);
        __va_start(ap, fmt);
        retval += kvprintf(fmt, ap);
        __va_end(ap);
        return retval;
}

static void
device_set_desc_internal(device_t dev, const char* desc, int copy)
{
        if (dev->desc && (dev->flags & DF_DESCMALLOCED)) {
                kfree(dev->desc, M_BUS);
                dev->flags &= ~DF_DESCMALLOCED;
                dev->desc = NULL;
        }

        if (copy && desc) {
                dev->desc = kmalloc(strlen(desc) + 1, M_BUS, M_INTWAIT);
                if (dev->desc) {
                        strcpy(dev->desc, desc);
                        dev->flags |= DF_DESCMALLOCED;
                }
        } else {
                /* Avoid a -Wcast-qual warning */
                dev->desc = (char *)(uintptr_t) desc;
        }

        bus_data_generation_update();
}

void
device_set_desc(device_t dev, const char* desc)
{
        device_set_desc_internal(dev, desc, FALSE);
}

void
device_set_desc_copy(device_t dev, const char* desc)
{
        device_set_desc_internal(dev, desc, TRUE);
}

void
device_set_flags(device_t dev, uint32_t flags)
{
        dev->devflags = flags;
}

void *
device_get_softc(device_t dev)
{
        return dev->softc;
}

void
device_set_softc(device_t dev, void *softc)
{
        if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC))
                kfree(dev->softc, M_BUS);
        dev->softc = softc;
        if (dev->softc)
                dev->flags |= DF_EXTERNALSOFTC;
        else
                dev->flags &= ~DF_EXTERNALSOFTC;
}

void
device_set_async_attach(device_t dev, int enable)
{
        if (enable)
                dev->flags |= DF_ASYNCPROBE;
        else
                dev->flags &= ~DF_ASYNCPROBE;
}

void *
device_get_ivars(device_t dev)
{
        return dev->ivars;
}

void
device_set_ivars(device_t dev, void * ivars)
{
        if (!dev)
                return;

        dev->ivars = ivars;
}

device_state_t
device_get_state(device_t dev)
{
        return(dev->state);
}

void
device_enable(device_t dev)
{
        dev->flags |= DF_ENABLED;
}

void
device_disable(device_t dev)
{
        dev->flags &= ~DF_ENABLED;
}

/*
 * YYY cannot block
 */
void
device_busy(device_t dev)
{
        if (dev->state < DS_ATTACHED)
                panic("device_busy: called for unattached device");
        if (dev->busy == 0 && dev->parent)
                device_busy(dev->parent);
        dev->busy++;
        dev->state = DS_BUSY;
}

/*
 * YYY cannot block
 */
void
device_unbusy(device_t dev)
{
        if (dev->state != DS_BUSY)
                panic("device_unbusy: called for non-busy device");
        dev->busy--;
        if (dev->busy == 0) {
                if (dev->parent)
                        device_unbusy(dev->parent);
                dev->state = DS_ATTACHED;
        }
}

void
device_quiet(device_t dev)
{
        dev->flags |= DF_QUIET;
}

void
device_verbose(device_t dev)
{
        dev->flags &= ~DF_QUIET;
}

int
device_is_quiet(device_t dev)
{
        return((dev->flags & DF_QUIET) != 0);
}

int
device_is_enabled(device_t dev)
{
        return((dev->flags & DF_ENABLED) != 0);
}

int
device_is_alive(device_t dev)
{
        return(dev->state >= DS_ALIVE);
}

int
device_is_attached(device_t dev)
{
        return(dev->state >= DS_ATTACHED);
}

int
device_set_devclass(device_t dev, const char *classname)
{
        devclass_t dc;
        int error;

        if (!classname) {
                if (dev->devclass)
                        devclass_delete_device(dev->devclass, dev);
                return(0);
        }

        if (dev->devclass) {
                kprintf("device_set_devclass: device class already set\n");
                return(EINVAL);
        }

        dc = devclass_find_internal(classname, NULL, TRUE);
        if (!dc)
                return(ENOMEM);

        error = devclass_add_device(dc, dev);

        bus_data_generation_update();
        return(error);
}

int
device_set_driver(device_t dev, driver_t *driver)
{
        if (dev->state >= DS_ATTACHED)
                return(EBUSY);

        if (dev->driver == driver)
                return(0);

        if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC)) {
                kfree(dev->softc, M_BUS);
                dev->softc = NULL;
        }
        device_set_desc(dev, NULL);
        kobj_delete((kobj_t) dev, 0);
        dev->driver = driver;
        if (driver) {
                kobj_init((kobj_t) dev, (kobj_class_t) driver);
                if (!(dev->flags & DF_EXTERNALSOFTC))
                        dev->softc = kmalloc(driver->size, M_BUS,
                                            M_INTWAIT | M_ZERO);
        } else {
                kobj_init((kobj_t) dev, &null_class);
        }

        bus_data_generation_update();
        return(0);
}

int
device_probe_and_attach(device_t dev)
{
        device_t bus = dev->parent;
        int error = 0;

        if (dev->state >= DS_ALIVE)
                return(0);

        if ((dev->flags & DF_ENABLED) == 0) {
                if (bootverbose) {
                        device_print_prettyname(dev);
                        kprintf("not probed (disabled)\n");
                }
                return(0);
        }

        error = device_probe_child(bus, dev);
        if (error) {
                if (!(dev->flags & DF_DONENOMATCH)) {
                        BUS_PROBE_NOMATCH(bus, dev);
                        devnomatch(dev);
                        dev->flags |= DF_DONENOMATCH;
                }
                return(error);
        }

        /*
         * Output the exact device chain prior to the attach in case the  
         * system locks up during attach, and generate the full info after
         * the attach so correct irq and other information is displayed.
         */
        if (bootverbose && !device_is_quiet(dev)) {
                device_t tmp;

                kprintf("%s", device_get_nameunit(dev));
                for (tmp = dev->parent; tmp; tmp = tmp->parent)
                        kprintf(".%s", device_get_nameunit(tmp));
                kprintf("\n");
        }
        if (!device_is_quiet(dev))
                device_print_child(bus, dev);
        if ((dev->flags & DF_ASYNCPROBE) && do_async_attach) {
                kprintf("%s: probing asynchronously\n",
                        device_get_nameunit(dev));
                dev->state = DS_INPROGRESS;
                device_attach_async(dev);
                error = 0;
        } else {
                error = device_doattach(dev);
        }
        return(error);
}

/*
 * Device is known to be alive, do the attach asynchronously.
 * However, serialize the attaches with the mp lock.
 */
static void
device_attach_async(device_t dev)
{
        thread_t td;

        atomic_add_int(&numasyncthreads, 1);
        lwkt_create(device_attach_thread, dev, &td, NULL,
                    0, 0, "%s", (dev->desc ? dev->desc : "devattach"));
}

static void
device_attach_thread(void *arg)
{
        device_t dev = arg;

        (void)device_doattach(dev);
        atomic_subtract_int(&numasyncthreads, 1);
        wakeup(&numasyncthreads);
}

/*
 * Device is known to be alive, do the attach (synchronous or asynchronous)
 */
static int
device_doattach(device_t dev)
{
        device_t bus = dev->parent;
        int hasclass = (dev->devclass != NULL);
        int error;

        device_sysctl_init(dev);
        error = DEVICE_ATTACH(dev);
        if (error == 0) {
                dev->state = DS_ATTACHED;
                if (bootverbose && !device_is_quiet(dev))
                        device_print_child(bus, dev);
                device_sysctl_update(dev);
                devadded(dev);
        } else {
                kprintf("device_probe_and_attach: %s%d attach returned %d\n",
                       dev->driver->name, dev->unit, error);
                /* Unset the class that was set in device_probe_child */
                if (!hasclass)
                        device_set_devclass(dev, 0);
                device_set_driver(dev, NULL);
                dev->state = DS_NOTPRESENT;
                device_sysctl_fini(dev);
        }
        return(error);
}

int
device_detach(device_t dev)
{
        int error;

        PDEBUG(("%s", DEVICENAME(dev)));
        if (dev->state == DS_BUSY)
                return(EBUSY);
        if (dev->state != DS_ATTACHED)
                return(0);

        if ((error = DEVICE_DETACH(dev)) != 0)
                return(error);
        devremoved(dev);
        device_printf(dev, "detached\n");
        if (dev->parent)
                BUS_CHILD_DETACHED(dev->parent, dev);

        if (!(dev->flags & DF_FIXEDCLASS))
                devclass_delete_device(dev->devclass, dev);

        dev->state = DS_NOTPRESENT;
        device_set_driver(dev, NULL);
        device_sysctl_fini(dev);

        return(0);
}

int
device_shutdown(device_t dev)
{
        if (dev->state < DS_ATTACHED)
                return 0;
        PDEBUG(("%s", DEVICENAME(dev)));
        return DEVICE_SHUTDOWN(dev);
}

int
device_set_unit(device_t dev, int unit)
{
        devclass_t dc;
        int err;

        dc = device_get_devclass(dev);
        if (unit < dc->maxunit && dc->devices[unit])
                return(EBUSY);
        err = devclass_delete_device(dc, dev);
        if (err)
                return(err);
        dev->unit = unit;
        err = devclass_add_device(dc, dev);
        if (err)
                return(err);

        bus_data_generation_update();
        return(0);
}

/*======================================*/
/*
 * Access functions for device resources.
 */

/* Supplied by config(8) in ioconf.c */
extern struct config_device config_devtab[];
extern int devtab_count;

/* Runtime version */
struct config_device *devtab = config_devtab;

static int
resource_new_name(const char *name, int unit)
{
        struct config_device *new;

        new = kmalloc((devtab_count + 1) * sizeof(*new), M_TEMP,
                     M_INTWAIT | M_ZERO);
        if (devtab && devtab_count > 0)
                bcopy(devtab, new, devtab_count * sizeof(*new));
        new[devtab_count].name = kmalloc(strlen(name) + 1, M_TEMP, M_INTWAIT);
        if (new[devtab_count].name == NULL) {
                kfree(new, M_TEMP);
                return(-1);
        }
        strcpy(new[devtab_count].name, name);
        new[devtab_count].unit = unit;
        new[devtab_count].resource_count = 0;
        new[devtab_count].resources = NULL;
        if (devtab && devtab != config_devtab)
                kfree(devtab, M_TEMP);
        devtab = new;
        return devtab_count++;
}

static int
resource_new_resname(int j, const char *resname, resource_type type)
{
        struct config_resource *new;
        int i;

        i = devtab[j].resource_count;
        new = kmalloc((i + 1) * sizeof(*new), M_TEMP, M_INTWAIT | M_ZERO);
        if (devtab[j].resources && i > 0)
                bcopy(devtab[j].resources, new, i * sizeof(*new));
        new[i].name = kmalloc(strlen(resname) + 1, M_TEMP, M_INTWAIT);
        if (new[i].name == NULL) {
                kfree(new, M_TEMP);
                return(-1);
        }
        strcpy(new[i].name, resname);
        new[i].type = type;
        if (devtab[j].resources)
                kfree(devtab[j].resources, M_TEMP);
        devtab[j].resources = new;
        devtab[j].resource_count = i + 1;
        return(i);
}

static int
resource_match_string(int i, const char *resname, const char *value)
{
        int j;
        struct config_resource *res;

        for (j = 0, res = devtab[i].resources;
             j < devtab[i].resource_count; j++, res++)
                if (!strcmp(res->name, resname)
                    && res->type == RES_STRING
                    && !strcmp(res->u.stringval, value))
                        return(j);
        return(-1);
}

static int
resource_find(const char *name, int unit, const char *resname, 
              struct config_resource **result)
{
        int i, j;
        struct config_resource *res;

        /*
         * First check specific instances, then generic.
         */
        for (i = 0; i < devtab_count; i++) {
                if (devtab[i].unit < 0)
                        continue;
                if (!strcmp(devtab[i].name, name) && devtab[i].unit == unit) {
                        res = devtab[i].resources;
                        for (j = 0; j < devtab[i].resource_count; j++, res++)
                                if (!strcmp(res->name, resname)) {
                                        *result = res;
                                        return(0);
                                }
                }
        }
        for (i = 0; i < devtab_count; i++) {
                if (devtab[i].unit >= 0)
                        continue;
                /* XXX should this `&& devtab[i].unit == unit' be here? */
                /* XXX if so, then the generic match does nothing */
                if (!strcmp(devtab[i].name, name) && devtab[i].unit == unit) {
                        res = devtab[i].resources;
                        for (j = 0; j < devtab[i].resource_count; j++, res++)
                                if (!strcmp(res->name, resname)) {
                                        *result = res;
                                        return(0);
                                }
                }
        }
        return(ENOENT);
}

static int
resource_kenv(const char *name, int unit, const char *resname, long *result)
{
        const char *env;
        char buf[64];

        ksnprintf(buf, sizeof(buf), "%s%d.%s", name, unit, resname);
        if ((env = kgetenv(buf)) != NULL) {
                *result = strtol(env, NULL, 0);
                return(0);
        }
        return (ENOENT);
}

int
resource_int_value(const char *name, int unit, const char *resname, int *result)
{
        struct config_resource *res;
        long kvalue = 0;
        int error;

        if (resource_kenv(name, unit, resname, &kvalue) == 0) {
                *result = (int)kvalue;
                return 0;
        }
        if ((error = resource_find(name, unit, resname, &res)) != 0)
                return(error);
        if (res->type != RES_INT)
                return(EFTYPE);
        *result = res->u.intval;
        return(0);
}

int
resource_long_value(const char *name, int unit, const char *resname,
                    long *result)
{
        struct config_resource *res;
        long kvalue;
        int error;

        if (resource_kenv(name, unit, resname, &kvalue) == 0) {
                *result = kvalue;
                return 0;
        }
        if ((error = resource_find(name, unit, resname, &res)) != 0)
                return(error);
        if (res->type != RES_LONG)
                return(EFTYPE);
        *result = res->u.longval;
        return(0);
}

int
resource_string_value(const char *name, int unit, const char *resname,
    const char **result)
{
        int error;
        struct config_resource *res;
        char buf[64];
        const char *env;

        ksnprintf(buf, sizeof(buf), "%s%d.%s", name, unit, resname);
        if ((env = kgetenv(buf)) != NULL) {
                *result = env;
                return 0;
        }

        if ((error = resource_find(name, unit, resname, &res)) != 0)
                return(error);
        if (res->type != RES_STRING)
                return(EFTYPE);
        *result = res->u.stringval;
        return(0);
}

int
resource_query_string(int i, const char *resname, const char *value)
{
        if (i < 0)
                i = 0;
        else
                i = i + 1;
        for (; i < devtab_count; i++)
                if (resource_match_string(i, resname, value) >= 0)
                        return(i);
        return(-1);
}

int
resource_locate(int i, const char *resname)
{
        if (i < 0)
                i = 0;
        else
                i = i + 1;
        for (; i < devtab_count; i++)
                if (!strcmp(devtab[i].name, resname))
                        return(i);
        return(-1);
}

int
resource_count(void)
{
        return(devtab_count);
}

char *
resource_query_name(int i)
{
        return(devtab[i].name);
}

int
resource_query_unit(int i)
{
        return(devtab[i].unit);
}

static int
resource_create(const char *name, int unit, const char *resname,
                resource_type type, struct config_resource **result)
{
        int i, j;
        struct config_resource *res = NULL;

        for (i = 0; i < devtab_count; i++)
                if (!strcmp(devtab[i].name, name) && devtab[i].unit == unit) {
                        res = devtab[i].resources;
                        break;
                }
        if (res == NULL) {
                i = resource_new_name(name, unit);
                if (i < 0)
                        return(ENOMEM);
                res = devtab[i].resources;
        }
        for (j = 0; j < devtab[i].resource_count; j++, res++)
                if (!strcmp(res->name, resname)) {
                        *result = res;
                        return(0);
                }
        j = resource_new_resname(i, resname, type);
        if (j < 0)
                return(ENOMEM);
        res = &devtab[i].resources[j];
        *result = res;
        return(0);
}

int
resource_set_int(const char *name, int unit, const char *resname, int value)
{
        int error;
        struct config_resource *res;

        error = resource_create(name, unit, resname, RES_INT, &res);
        if (error)
                return(error);
        if (res->type != RES_INT)
                return(EFTYPE);
        res->u.intval = value;
        return(0);
}

int
resource_set_long(const char *name, int unit, const char *resname, long value)
{
        int error;
        struct config_resource *res;

        error = resource_create(name, unit, resname, RES_LONG, &res);
        if (error)
                return(error);
        if (res->type != RES_LONG)
                return(EFTYPE);
        res->u.longval = value;
        return(0);
}

int
resource_set_string(const char *name, int unit, const char *resname,
                    const char *value)
{
        int error;
        struct config_resource *res;

        error = resource_create(name, unit, resname, RES_STRING, &res);
        if (error)
                return(error);
        if (res->type != RES_STRING)
                return(EFTYPE);
        if (res->u.stringval)
                kfree(res->u.stringval, M_TEMP);
        res->u.stringval = kmalloc(strlen(value) + 1, M_TEMP, M_INTWAIT);
        if (res->u.stringval == NULL)
                return(ENOMEM);
        strcpy(res->u.stringval, value);
        return(0);
}

static void
resource_cfgload(void *dummy __unused)
{
        struct config_resource *res, *cfgres;
        int i, j;
        int error;
        char *name, *resname;
        int unit;
        resource_type type;
        char *stringval;
        int config_devtab_count;

        config_devtab_count = devtab_count;
        devtab = NULL;
        devtab_count = 0;

        for (i = 0; i < config_devtab_count; i++) {
                name = config_devtab[i].name;
                unit = config_devtab[i].unit;

                for (j = 0; j < config_devtab[i].resource_count; j++) {
                        cfgres = config_devtab[i].resources;
                        resname = cfgres[j].name;
                        type = cfgres[j].type;
                        error = resource_create(name, unit, resname, type,
                                                &res);
                        if (error) {
                                kprintf("create resource %s%d: error %d\n",
                                        name, unit, error);
                                continue;
                        }
                        if (res->type != type) {
                                kprintf("type mismatch %s%d: %d != %d\n",
                                        name, unit, res->type, type);
                                continue;
                        }
                        switch (type) {
                        case RES_INT:
                                res->u.intval = cfgres[j].u.intval;
                                break;
                        case RES_LONG:
                                res->u.longval = cfgres[j].u.longval;
                                break;
                        case RES_STRING:
                                if (res->u.stringval)
                                        kfree(res->u.stringval, M_TEMP);
                                stringval = cfgres[j].u.stringval;
                                res->u.stringval = kmalloc(strlen(stringval) + 1,
                                                          M_TEMP, M_INTWAIT);
                                if (res->u.stringval == NULL)
                                        break;
                                strcpy(res->u.stringval, stringval);
                                break;
                        default:
                                panic("unknown resource type %d", type);
                        }
                }
        }
}
SYSINIT(cfgload, SI_BOOT1_POST, SI_ORDER_ANY + 50, resource_cfgload, 0);


/*======================================*/
/*
 * Some useful method implementations to make life easier for bus drivers.
 */

void
resource_list_init(struct resource_list *rl)
{
        SLIST_INIT(rl);
}

void
resource_list_free(struct resource_list *rl)
{
        struct resource_list_entry *rle;

        while ((rle = SLIST_FIRST(rl)) != NULL) {
                if (rle->res)
                        panic("resource_list_free: resource entry is busy");
                SLIST_REMOVE_HEAD(rl, link);
                kfree(rle, M_BUS);
        }
}

void
resource_list_add(struct resource_list *rl, int type, int rid,
    u_long start, u_long end, u_long count, int cpuid)
{
        struct resource_list_entry *rle;

        rle = resource_list_find(rl, type, rid);
        if (rle == NULL) {
                rle = kmalloc(sizeof(struct resource_list_entry), M_BUS,
                             M_INTWAIT);
                SLIST_INSERT_HEAD(rl, rle, link);
                rle->type = type;
                rle->rid = rid;
                rle->res = NULL;
                rle->cpuid = -1;
        }

        if (rle->res)
                panic("resource_list_add: resource entry is busy");

        rle->start = start;
        rle->end = end;
        rle->count = count;

        if (cpuid != -1) {
                if (rle->cpuid != -1 && rle->cpuid != cpuid) {
                        panic("resource_list_add: moving from cpu%d -> cpu%d",
                            rle->cpuid, cpuid);
                }
                rle->cpuid = cpuid;
        }
}

struct resource_list_entry*
resource_list_find(struct resource_list *rl,
                   int type, int rid)
{
        struct resource_list_entry *rle;

        SLIST_FOREACH(rle, rl, link)
                if (rle->type == type && rle->rid == rid)
                        return(rle);
        return(NULL);
}

void
resource_list_delete(struct resource_list *rl,
                     int type, int rid)
{
        struct resource_list_entry *rle = resource_list_find(rl, type, rid);

        if (rle) {
                if (rle->res != NULL)
                        panic("resource_list_delete: resource has not been released");
                SLIST_REMOVE(rl, rle, resource_list_entry, link);
                kfree(rle, M_BUS);
        }
}

struct resource *
resource_list_alloc(struct resource_list *rl,
                    device_t bus, device_t child,
                    int type, int *rid,
                    u_long start, u_long end,
                    u_long count, u_int flags, int cpuid)
{
        struct resource_list_entry *rle = NULL;
        int passthrough = (device_get_parent(child) != bus);
        int isdefault = (start == 0UL && end == ~0UL);

        if (passthrough) {
                return(BUS_ALLOC_RESOURCE(device_get_parent(bus), child,
                                          type, rid,
                                          start, end, count, flags, cpuid));
        }

        rle = resource_list_find(rl, type, *rid);

        if (!rle)
                return(0);              /* no resource of that type/rid */

        if (rle->res)
                panic("resource_list_alloc: resource entry is busy");

        if (isdefault) {
                start = rle->start;
                count = max(count, rle->count);
                end = max(rle->end, start + count - 1);
        }
        cpuid = rle->cpuid;

        rle->res = BUS_ALLOC_RESOURCE(device_get_parent(bus), child,
                                      type, rid, start, end, count,
                                      flags, cpuid);

        /*
         * Record the new range.
         */
        if (rle->res) {
                rle->start = rman_get_start(rle->res);
                rle->end = rman_get_end(rle->res);
                rle->count = count;
        }

        return(rle->res);
}

int
resource_list_release(struct resource_list *rl,
                      device_t bus, device_t child,
                      int type, int rid, struct resource *res)
{
        struct resource_list_entry *rle = NULL;
        int passthrough = (device_get_parent(child) != bus);
        int error;

        if (passthrough) {
                return(BUS_RELEASE_RESOURCE(device_get_parent(bus), child,
                                            type, rid, res));
        }

        rle = resource_list_find(rl, type, rid);

        if (!rle)
                panic("resource_list_release: can't find resource");
        if (!rle->res)
                panic("resource_list_release: resource entry is not busy");

        error = BUS_RELEASE_RESOURCE(device_get_parent(bus), child,
                                     type, rid, res);
        if (error)
                return(error);

        rle->res = NULL;
        return(0);
}

int
resource_list_print_type(struct resource_list *rl, const char *name, int type,
                         const char *format)
{
        struct resource_list_entry *rle;
        int printed, retval;

        printed = 0;
        retval = 0;
        /* Yes, this is kinda cheating */
        SLIST_FOREACH(rle, rl, link) {
                if (rle->type == type) {
                        if (printed == 0)
                                retval += kprintf(" %s ", name);
                        else
                                retval += kprintf(",");
                        printed++;
                        retval += kprintf(format, rle->start);
                        if (rle->count > 1) {
                                retval += kprintf("-");
                                retval += kprintf(format, rle->start +
                                                 rle->count - 1);
                        }
                }
        }
        return(retval);
}

/*
 * Generic driver/device identify functions.  These will install a device
 * rendezvous point under the parent using the same name as the driver
 * name, which will at a later time be probed and attached.
 *
 * These functions are used when the parent does not 'scan' its bus for
 * matching devices, or for the particular devices using these functions,
 * or when the device is a pseudo or synthesized device (such as can be
 * found under firewire and ppbus).
 */
int
bus_generic_identify(driver_t *driver, device_t parent)
{
        if (parent->state == DS_ATTACHED)
                return (0);
        BUS_ADD_CHILD(parent, parent, 0, driver->name, -1);
        return (0);
}

int
bus_generic_identify_sameunit(driver_t *driver, device_t parent)
{
        if (parent->state == DS_ATTACHED)
                return (0);
        BUS_ADD_CHILD(parent, parent, 0, driver->name, device_get_unit(parent));
        return (0);
}

/*
 * Call DEVICE_IDENTIFY for each driver.
 */
int
bus_generic_probe(device_t dev)
{
        devclass_t dc = dev->devclass;
        driverlink_t dl;

        TAILQ_FOREACH(dl, &dc->drivers, link) {
                DEVICE_IDENTIFY(dl->driver, dev);
        }

        return(0);
}

/*
 * This is an aweful hack due to the isa bus and autoconf code not
 * probing the ISA devices until after everything else has configured.
 * The ISA bus did a dummy attach long ago so we have to set it back
 * to an earlier state so the probe thinks its the initial probe and
 * not a bus rescan.
 *
 * XXX remove by properly defering the ISA bus scan.
 */
int
bus_generic_probe_hack(device_t dev)
{
        if (dev->state == DS_ATTACHED) {
                dev->state = DS_ALIVE;
                bus_generic_probe(dev);
                dev->state = DS_ATTACHED;
        }
        return (0);
}

int
bus_generic_attach(device_t dev)
{
        device_t child;

        TAILQ_FOREACH(child, &dev->children, link) {
                device_probe_and_attach(child);
        }

        return(0);
}

int
bus_generic_detach(device_t dev)
{
        device_t child;
        int error;

        if (dev->state != DS_ATTACHED)
                return(EBUSY);

        TAILQ_FOREACH(child, &dev->children, link)
                if ((error = device_detach(child)) != 0)
                        return(error);

        return 0;
}

int
bus_generic_shutdown(device_t dev)
{
        device_t child;

        TAILQ_FOREACH(child, &dev->children, link)
                device_shutdown(child);

        return(0);
}

int
bus_generic_suspend(device_t dev)
{
        int error;
        device_t child, child2;

        TAILQ_FOREACH(child, &dev->children, link) {
                error = DEVICE_SUSPEND(child);
                if (error) {
                        for (child2 = TAILQ_FIRST(&dev->children);
                             child2 && child2 != child; 
                             child2 = TAILQ_NEXT(child2, link))
                                DEVICE_RESUME(child2);
                        return(error);
                }
        }
        return(0);
}

int
bus_generic_resume(device_t dev)
{
        device_t child;

        TAILQ_FOREACH(child, &dev->children, link)
                DEVICE_RESUME(child);
                /* if resume fails, there's nothing we can usefully do... */

        return(0);
}

int
bus_print_child_header(device_t dev, device_t child)
{
        int retval = 0;

        if (device_get_desc(child))
                retval += device_printf(child, "<%s>", device_get_desc(child));
        else
                retval += kprintf("%s", device_get_nameunit(child));
        if (bootverbose) {
                if (child->state != DS_ATTACHED)
                        kprintf(" [tentative]");
                else
                        kprintf(" [attached!]");
        }
        return(retval);
}

int
bus_print_child_footer(device_t dev, device_t child)
{
        return(kprintf(" on %s\n", device_get_nameunit(dev)));
}

device_t
bus_generic_add_child(device_t dev, device_t child, int order,
                      const char *name, int unit)
{
        if (dev->parent)
                dev = BUS_ADD_CHILD(dev->parent, child, order, name, unit);
        else
                dev = device_add_child_ordered(child, order, name, unit);
        return(dev);
                
}

int
bus_generic_print_child(device_t dev, device_t child)
{
        int retval = 0;

        retval += bus_print_child_header(dev, child);
        retval += bus_print_child_footer(dev, child);

        return(retval);
}

int
bus_generic_read_ivar(device_t dev, device_t child, int index, 
                      uintptr_t * result)
{
        int error;

        if (dev->parent)
                error = BUS_READ_IVAR(dev->parent, child, index, result);
        else
                error = ENOENT;
        return (error);
}

int
bus_generic_write_ivar(device_t dev, device_t child, int index, 
                       uintptr_t value)
{
        int error;

        if (dev->parent)
                error = BUS_WRITE_IVAR(dev->parent, child, index, value);
        else
                error = ENOENT;
        return (error);
}

/*
 * Resource list are used for iterations, do not recurse.
 */
struct resource_list *
bus_generic_get_resource_list(device_t dev, device_t child)
{
        return (NULL);
}

void
bus_generic_driver_added(device_t dev, driver_t *driver)
{
        device_t child;

        DEVICE_IDENTIFY(driver, dev);
        TAILQ_FOREACH(child, &dev->children, link) {
                if (child->state == DS_NOTPRESENT)
                        device_probe_and_attach(child);
        }
}

int
bus_generic_setup_intr(device_t dev, device_t child, struct resource *irq,
    int flags, driver_intr_t *intr, void *arg, void **cookiep,
    lwkt_serialize_t serializer, const char *desc)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent) {
                return BUS_SETUP_INTR(dev->parent, child, irq, flags,
                    intr, arg, cookiep, serializer, desc);
        } else {
                return EINVAL;
        }
}

int
bus_generic_teardown_intr(device_t dev, device_t child, struct resource *irq,
                          void *cookie)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_TEARDOWN_INTR(dev->parent, child, irq, cookie));
        else
                return(EINVAL);
}

int
bus_generic_disable_intr(device_t dev, device_t child, void *cookie)
{
        if (dev->parent)
                return(BUS_DISABLE_INTR(dev->parent, child, cookie));
        else
                return(0);
}

void
bus_generic_enable_intr(device_t dev, device_t child, void *cookie)
{
        if (dev->parent)
                BUS_ENABLE_INTR(dev->parent, child, cookie);
}

int
bus_generic_config_intr(device_t dev, device_t child, int irq, enum intr_trigger trig,
    enum intr_polarity pol)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_CONFIG_INTR(dev->parent, child, irq, trig, pol));
        else
                return(EINVAL);
}

struct resource *
bus_generic_alloc_resource(device_t dev, device_t child, int type, int *rid,
    u_long start, u_long end, u_long count, u_int flags, int cpuid)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_ALLOC_RESOURCE(dev->parent, child, type, rid, 
                                           start, end, count, flags, cpuid));
        else
                return(NULL);
}

int
bus_generic_release_resource(device_t dev, device_t child, int type, int rid,
                             struct resource *r)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_RELEASE_RESOURCE(dev->parent, child, type, rid, r));
        else
                return(EINVAL);
}

int
bus_generic_activate_resource(device_t dev, device_t child, int type, int rid,
                              struct resource *r)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_ACTIVATE_RESOURCE(dev->parent, child, type, rid, r));
        else
                return(EINVAL);
}

int
bus_generic_deactivate_resource(device_t dev, device_t child, int type,
                                int rid, struct resource *r)
{
        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent)
                return(BUS_DEACTIVATE_RESOURCE(dev->parent, child, type, rid,
                                               r));
        else
                return(EINVAL);
}

int
bus_generic_get_resource(device_t dev, device_t child, int type, int rid,
                         u_long *startp, u_long *countp)
{
        int error;

        error = ENOENT;
        if (dev->parent) {
                error = BUS_GET_RESOURCE(dev->parent, child, type, rid, 
                                         startp, countp);
        }
        return (error);
}

int
bus_generic_set_resource(device_t dev, device_t child, int type, int rid,
                        u_long start, u_long count, int cpuid)
{
        int error;

        error = EINVAL;
        if (dev->parent) {
                error = BUS_SET_RESOURCE(dev->parent, child, type, rid, 
                                         start, count, cpuid);
        }
        return (error);
}

void
bus_generic_delete_resource(device_t dev, device_t child, int type, int rid)
{
        if (dev->parent)
                BUS_DELETE_RESOURCE(dev, child, type, rid);
}

/**
 * @brief Helper function for implementing BUS_GET_DMA_TAG().
 *
 * This simple implementation of BUS_GET_DMA_TAG() simply calls the
 * BUS_GET_DMA_TAG() method of the parent of @p dev.
 */
bus_dma_tag_t
bus_generic_get_dma_tag(device_t dev, device_t child)
{

        /* Propagate up the bus hierarchy until someone handles it. */
        if (dev->parent != NULL)
                return (BUS_GET_DMA_TAG(dev->parent, child));
        return (NULL);
}

int
bus_generic_rl_get_resource(device_t dev, device_t child, int type, int rid,
    u_long *startp, u_long *countp)
{
        struct resource_list *rl = NULL;
        struct resource_list_entry *rle = NULL;

        rl = BUS_GET_RESOURCE_LIST(dev, child);
        if (!rl)
                return(EINVAL);

        rle = resource_list_find(rl, type, rid);
        if (!rle)
                return(ENOENT);

        if (startp)
                *startp = rle->start;
        if (countp)
                *countp = rle->count;

        return(0);
}

int
bus_generic_rl_set_resource(device_t dev, device_t child, int type, int rid,
    u_long start, u_long count, int cpuid)
{
        struct resource_list *rl = NULL;

        rl = BUS_GET_RESOURCE_LIST(dev, child);
        if (!rl)
                return(EINVAL);

        resource_list_add(rl, type, rid, start, (start + count - 1), count,
            cpuid);

        return(0);
}

void
bus_generic_rl_delete_resource(device_t dev, device_t child, int type, int rid)
{
        struct resource_list *rl = NULL;

        rl = BUS_GET_RESOURCE_LIST(dev, child);
        if (!rl)
                return;

        resource_list_delete(rl, type, rid);
}

int
bus_generic_rl_release_resource(device_t dev, device_t child, int type,
    int rid, struct resource *r)
{
        struct resource_list *rl = NULL;

        rl = BUS_GET_RESOURCE_LIST(dev, child);
        if (!rl)
                return(EINVAL);

        return(resource_list_release(rl, dev, child, type, rid, r));
}

struct resource *
bus_generic_rl_alloc_resource(device_t dev, device_t child, int type,
    int *rid, u_long start, u_long end, u_long count, u_int flags, int cpuid)
{
        struct resource_list *rl = NULL;

        rl = BUS_GET_RESOURCE_LIST(dev, child);
        if (!rl)
                return(NULL);

        return(resource_list_alloc(rl, dev, child, type, rid,
            start, end, count, flags, cpuid));
}

int
bus_generic_child_present(device_t bus, device_t child)
{
        return(BUS_CHILD_PRESENT(device_get_parent(bus), bus));
}


/*
 * Some convenience functions to make it easier for drivers to use the
 * resource-management functions.  All these really do is hide the
 * indirection through the parent's method table, making for slightly
 * less-wordy code.  In the future, it might make sense for this code
 * to maintain some sort of a list of resources allocated by each device.
 */
int
bus_alloc_resources(device_t dev, struct resource_spec *rs,
    struct resource **res)
{
        int i;

        for (i = 0; rs[i].type != -1; i++)
                res[i] = NULL;
        for (i = 0; rs[i].type != -1; i++) {
                res[i] = bus_alloc_resource_any(dev,
                    rs[i].type, &rs[i].rid, rs[i].flags);
                if (res[i] == NULL) {
                        bus_release_resources(dev, rs, res);
                        return (ENXIO);
                }
        }
        return (0);
}

void
bus_release_resources(device_t dev, const struct resource_spec *rs,
    struct resource **res)
{
        int i;

        for (i = 0; rs[i].type != -1; i++)
                if (res[i] != NULL) {
                        bus_release_resource(
                            dev, rs[i].type, rs[i].rid, res[i]);
                        res[i] = NULL;
                }
}

struct resource *
bus_alloc_resource(device_t dev, int type, int *rid, u_long start, u_long end,
                   u_long count, u_int flags)
{
        if (dev->parent == NULL)
                return(0);
        return(BUS_ALLOC_RESOURCE(dev->parent, dev, type, rid, start, end,
                                  count, flags, -1));
}

struct resource *
bus_alloc_legacy_irq_resource(device_t dev, int *rid, u_long irq, u_int flags)
{
        if (dev->parent == NULL)
                return(0);
        return BUS_ALLOC_RESOURCE(dev->parent, dev, SYS_RES_IRQ, rid,
            irq, irq, 1, flags, machintr_legacy_intr_cpuid(irq));
}

int
bus_activate_resource(device_t dev, int type, int rid, struct resource *r)
{
        if (dev->parent == NULL)
                return(EINVAL);
        return(BUS_ACTIVATE_RESOURCE(dev->parent, dev, type, rid, r));
}

int
bus_deactivate_resource(device_t dev, int type, int rid, struct resource *r)
{
        if (dev->parent == NULL)
                return(EINVAL);
        return(BUS_DEACTIVATE_RESOURCE(dev->parent, dev, type, rid, r));
}

int
bus_release_resource(device_t dev, int type, int rid, struct resource *r)
{
        if (dev->parent == NULL)
                return(EINVAL);
        return(BUS_RELEASE_RESOURCE(dev->parent, dev, type, rid, r));
}

int
bus_setup_intr_descr(device_t dev, struct resource *r, int flags,
    driver_intr_t handler, void *arg, void **cookiep,
    lwkt_serialize_t serializer, const char *desc)
{
        if (dev->parent == NULL)
                return EINVAL;
        return BUS_SETUP_INTR(dev->parent, dev, r, flags, handler, arg,
            cookiep, serializer, desc);
}

int
bus_setup_intr(device_t dev, struct resource *r, int flags,
    driver_intr_t handler, void *arg, void **cookiep,
    lwkt_serialize_t serializer)
{
        return bus_setup_intr_descr(dev, r, flags, handler, arg, cookiep,
            serializer, NULL);
}

int
bus_teardown_intr(device_t dev, struct resource *r, void *cookie)
{
        if (dev->parent == NULL)
                return(EINVAL);
        return(BUS_TEARDOWN_INTR(dev->parent, dev, r, cookie));
}

void
bus_enable_intr(device_t dev, void *cookie)
{
        if (dev->parent)
                BUS_ENABLE_INTR(dev->parent, dev, cookie);
}

int
bus_disable_intr(device_t dev, void *cookie)
{
        if (dev->parent)
                return(BUS_DISABLE_INTR(dev->parent, dev, cookie));
        else
                return(0);
}

int
bus_set_resource(device_t dev, int type, int rid,
                 u_long start, u_long count, int cpuid)
{
        return(BUS_SET_RESOURCE(device_get_parent(dev), dev, type, rid,
                                start, count, cpuid));
}

int
bus_get_resource(device_t dev, int type, int rid,
                 u_long *startp, u_long *countp)
{
        return(BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
                                startp, countp));
}

u_long
bus_get_resource_start(device_t dev, int type, int rid)
{
        u_long start, count;
        int error;

        error = BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
                                 &start, &count);
        if (error)
                return(0);
        return(start);
}

u_long
bus_get_resource_count(device_t dev, int type, int rid)
{
        u_long start, count;
        int error;

        error = BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
                                 &start, &count);
        if (error)
                return(0);
        return(count);
}

void
bus_delete_resource(device_t dev, int type, int rid)
{
        BUS_DELETE_RESOURCE(device_get_parent(dev), dev, type, rid);
}

int
bus_child_present(device_t child)
{
        return (BUS_CHILD_PRESENT(device_get_parent(child), child));
}

int
bus_child_pnpinfo_str(device_t child, char *buf, size_t buflen)
{
        device_t parent;

        parent = device_get_parent(child);
        if (parent == NULL) {
                *buf = '\0';
                return (0);
        }
        return (BUS_CHILD_PNPINFO_STR(parent, child, buf, buflen));
}

int
bus_child_location_str(device_t child, char *buf, size_t buflen)
{
        device_t parent;

        parent = device_get_parent(child);
        if (parent == NULL) {
                *buf = '\0';
                return (0);
        }
        return (BUS_CHILD_LOCATION_STR(parent, child, buf, buflen));
}

/**
 * @brief Wrapper function for BUS_GET_DMA_TAG().
 *
 * This function simply calls the BUS_GET_DMA_TAG() method of the
 * parent of @p dev.
 */
bus_dma_tag_t
bus_get_dma_tag(device_t dev)
{
        device_t parent;

        parent = device_get_parent(dev);
        if (parent == NULL)
                return (NULL);
        return (BUS_GET_DMA_TAG(parent, dev));
}

static int
root_print_child(device_t dev, device_t child)
{
        return(0);
}

static int
root_setup_intr(device_t dev, device_t child, driver_intr_t *intr, void *arg,
                void **cookiep, lwkt_serialize_t serializer, const char *desc)
{
        /*
         * If an interrupt mapping gets to here something bad has happened.
         */
        panic("root_setup_intr");
}

/*
 * If we get here, assume that the device is permanant and really is
 * present in the system.  Removable bus drivers are expected to intercept
 * this call long before it gets here.  We return -1 so that drivers that
 * really care can check vs -1 or some ERRNO returned higher in the food
 * chain.
 */
static int
root_child_present(device_t dev, device_t child)
{
        return(-1);
}

/*
 * XXX NOTE! other defaults may be set in bus_if.m
 */
static kobj_method_t root_methods[] = {
        /* Device interface */
        KOBJMETHOD(device_shutdown,     bus_generic_shutdown),
        KOBJMETHOD(device_suspend,      bus_generic_suspend),
        KOBJMETHOD(device_resume,       bus_generic_resume),

        /* Bus interface */
        KOBJMETHOD(bus_add_child,       bus_generic_add_child),
        KOBJMETHOD(bus_print_child,     root_print_child),
        KOBJMETHOD(bus_read_ivar,       bus_generic_read_ivar),
        KOBJMETHOD(bus_write_ivar,      bus_generic_write_ivar),
        KOBJMETHOD(bus_setup_intr,      root_setup_intr),
        KOBJMETHOD(bus_child_present,   root_child_present),

        KOBJMETHOD_END
};

static driver_t root_driver = {
        "root",
        root_methods,
        1,                      /* no softc */
};

device_t        root_bus;
devclass_t      root_devclass;

static int
root_bus_module_handler(module_t mod, int what, void* arg)
{
        switch (what) {
        case MOD_LOAD:
                TAILQ_INIT(&bus_data_devices);
                root_bus = make_device(NULL, "root", 0);
                root_bus->desc = "System root bus";
                kobj_init((kobj_t) root_bus, (kobj_class_t) &root_driver);
                root_bus->driver = &root_driver;
                root_bus->state = DS_ALIVE;
                root_devclass = devclass_find_internal("root", NULL, FALSE);
                devinit();
                return(0);

        case MOD_SHUTDOWN:
                device_shutdown(root_bus);
                return(0);
        default:
                return(0);
        }
}

static moduledata_t root_bus_mod = {
        "rootbus",
        root_bus_module_handler,
        0
};
DECLARE_MODULE(rootbus, root_bus_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);

void
root_bus_configure(void)
{
        int warncount;
        device_t dev;

        PDEBUG(("."));

        /*
         * handle device_identify based device attachments to the root_bus
         * (typically nexus).
         */
        bus_generic_probe(root_bus);

        /*
         * Probe and attach the devices under root_bus.
         */
        TAILQ_FOREACH(dev, &root_bus->children, link) {
                device_probe_and_attach(dev);
        }

        /*
         * Wait for all asynchronous attaches to complete.  If we don't
         * our legacy ISA bus scan could steal device unit numbers or
         * even I/O ports.
         */
        warncount = 10;
        if (numasyncthreads)
                kprintf("Waiting for async drivers to attach\n");
        while (numasyncthreads > 0) {
                if (tsleep(&numasyncthreads, 0, "rootbus", hz) == EWOULDBLOCK)
                        --warncount;
                if (warncount == 0) {
                        kprintf("Warning: Still waiting for %d "
                                "drivers to attach\n", numasyncthreads);
                } else if (warncount == -30) {
                        kprintf("Giving up on %d drivers\n", numasyncthreads);
                        break;
                }
        }
        root_bus->state = DS_ATTACHED;
}

int
driver_module_handler(module_t mod, int what, void *arg)
{
        int error;
        struct driver_module_data *dmd;
        devclass_t bus_devclass;
        kobj_class_t driver;
        const char *parentname;

        dmd = (struct driver_module_data *)arg;
        bus_devclass = devclass_find_internal(dmd->dmd_busname, NULL, TRUE);
        error = 0;

        switch (what) {
        case MOD_LOAD:
                if (dmd->dmd_chainevh)
                        error = dmd->dmd_chainevh(mod,what,dmd->dmd_chainarg);

                driver = dmd->dmd_driver;
                PDEBUG(("Loading module: driver %s on bus %s",
                        DRIVERNAME(driver), dmd->dmd_busname));

                /*
                 * If the driver has any base classes, make the
                 * devclass inherit from the devclass of the driver's
                 * first base class. This will allow the system to
                 * search for drivers in both devclasses for children
                 * of a device using this driver.
                 */
                if (driver->baseclasses)
                        parentname = driver->baseclasses[0]->name;
                else
                        parentname = NULL;
                *dmd->dmd_devclass = devclass_find_internal(driver->name,
                                                            parentname, TRUE);

                error = devclass_add_driver(bus_devclass, driver);
                if (error)
                        break;
                break;

        case MOD_UNLOAD:
                PDEBUG(("Unloading module: driver %s from bus %s",
                        DRIVERNAME(dmd->dmd_driver), dmd->dmd_busname));
                error = devclass_delete_driver(bus_devclass, dmd->dmd_driver);

                if (!error && dmd->dmd_chainevh)
                        error = dmd->dmd_chainevh(mod,what,dmd->dmd_chainarg);
                break;
        }

        return (error);
}

#ifdef BUS_DEBUG

/*
 * The _short versions avoid iteration by not calling anything that prints
 * more than oneliners. I love oneliners.
 */

static void
print_device_short(device_t dev, int indent)
{
        if (!dev)
                return;

        indentprintf(("device %d: <%s> %sparent,%schildren,%s%s%s%s,%sivars,%ssoftc,busy=%d\n",
                      dev->unit, dev->desc,
                      (dev->parent? "":"no "),
                      (TAILQ_EMPTY(&dev->children)? "no ":""),
                      (dev->flags&DF_ENABLED? "enabled,":"disabled,"),
                      (dev->flags&DF_FIXEDCLASS? "fixed,":""),
                      (dev->flags&DF_WILDCARD? "wildcard,":""),
                      (dev->flags&DF_DESCMALLOCED? "descmalloced,":""),
                      (dev->ivars? "":"no "),
                      (dev->softc? "":"no "),
                      dev->busy));
}

static void
print_device(device_t dev, int indent)
{
        if (!dev)
                return;

        print_device_short(dev, indent);

        indentprintf(("Parent:\n"));
        print_device_short(dev->parent, indent+1);
        indentprintf(("Driver:\n"));
        print_driver_short(dev->driver, indent+1);
        indentprintf(("Devclass:\n"));
        print_devclass_short(dev->devclass, indent+1);
}

/*
 * Print the device and all its children (indented).
 */
void
print_device_tree_short(device_t dev, int indent)
{
        device_t child;

        if (!dev)
                return;

        print_device_short(dev, indent);

        TAILQ_FOREACH(child, &dev->children, link)
                print_device_tree_short(child, indent+1);
}

/*
 * Print the device and all its children (indented).
 */
void
print_device_tree(device_t dev, int indent)
{
        device_t child;

        if (!dev)
                return;

        print_device(dev, indent);

        TAILQ_FOREACH(child, &dev->children, link)
                print_device_tree(child, indent+1);
}

static void
print_driver_short(driver_t *driver, int indent)
{
        if (!driver)
                return;

        indentprintf(("driver %s: softc size = %zu\n",
                      driver->name, driver->size));
}

static void
print_driver(driver_t *driver, int indent)
{
        if (!driver)
                return;

        print_driver_short(driver, indent);
}


static void
print_driver_list(driver_list_t drivers, int indent)
{
        driverlink_t driver;

        TAILQ_FOREACH(driver, &drivers, link)
                print_driver(driver->driver, indent);
}

static void
print_devclass_short(devclass_t dc, int indent)
{
        if (!dc)
                return;

        indentprintf(("devclass %s: max units = %d\n", dc->name, dc->maxunit));
}

static void
print_devclass(devclass_t dc, int indent)
{
        int i;

        if (!dc)
                return;

        print_devclass_short(dc, indent);
        indentprintf(("Drivers:\n"));
        print_driver_list(dc->drivers, indent+1);

        indentprintf(("Devices:\n"));
        for (i = 0; i < dc->maxunit; i++)
                if (dc->devices[i])
                        print_device(dc->devices[i], indent+1);
}

void
print_devclass_list_short(void)
{
        devclass_t dc;

        kprintf("Short listing of devclasses, drivers & devices:\n");
        TAILQ_FOREACH(dc, &devclasses, link) {
                print_devclass_short(dc, 0);
        }
}

void
print_devclass_list(void)
{
        devclass_t dc;

        kprintf("Full listing of devclasses, drivers & devices:\n");
        TAILQ_FOREACH(dc, &devclasses, link) {
                print_devclass(dc, 0);
        }
}

#endif

/*
 * Check to see if a device is disabled via a disabled hint.
 */
int
resource_disabled(const char *name, int unit)
{
        int error, value;

        error = resource_int_value(name, unit, "disabled", &value);
        if (error)
               return(0);
        return(value);
}

/*
 * User-space access to the device tree.
 *
 * We implement a small set of nodes:
 *
 * hw.bus                       Single integer read method to obtain the
 *                              current generation count.
 * hw.bus.devices               Reads the entire device tree in flat space.
 * hw.bus.rman                  Resource manager interface
 *
 * We might like to add the ability to scan devclasses and/or drivers to
 * determine what else is currently loaded/available.
 */

static int
sysctl_bus(SYSCTL_HANDLER_ARGS)
{
        struct u_businfo        ubus;

        ubus.ub_version = BUS_USER_VERSION;
        ubus.ub_generation = bus_data_generation;

        return (SYSCTL_OUT(req, &ubus, sizeof(ubus)));
}
SYSCTL_NODE(_hw_bus, OID_AUTO, info, CTLFLAG_RW, sysctl_bus,
    "bus-related data");

static int
sysctl_devices(SYSCTL_HANDLER_ARGS)
{
        int                     *name = (int *)arg1;
        u_int                   namelen = arg2;
        int                     index;
        struct device           *dev;
        struct u_device         udev;   /* XXX this is a bit big */
        int                     error;

        if (namelen != 2)
                return (EINVAL);

        if (bus_data_generation_check(name[0]))
                return (EINVAL);

        index = name[1];

        /*
         * Scan the list of devices, looking for the requested index.
         */
        TAILQ_FOREACH(dev, &bus_data_devices, devlink) {
                if (index-- == 0)
                        break;
        }
        if (dev == NULL)
                return (ENOENT);

        /*
         * Populate the return array.
         */
        bzero(&udev, sizeof(udev));
        udev.dv_handle = (uintptr_t)dev;
        udev.dv_parent = (uintptr_t)dev->parent;
        if (dev->nameunit != NULL)
                strlcpy(udev.dv_name, dev->nameunit, sizeof(udev.dv_name));
        if (dev->desc != NULL)
                strlcpy(udev.dv_desc, dev->desc, sizeof(udev.dv_desc));
        if (dev->driver != NULL && dev->driver->name != NULL)
                strlcpy(udev.dv_drivername, dev->driver->name,
                    sizeof(udev.dv_drivername));
        bus_child_pnpinfo_str(dev, udev.dv_pnpinfo, sizeof(udev.dv_pnpinfo));
        bus_child_location_str(dev, udev.dv_location, sizeof(udev.dv_location));
        udev.dv_devflags = dev->devflags;
        udev.dv_flags = dev->flags;
        udev.dv_state = dev->state;
        error = SYSCTL_OUT(req, &udev, sizeof(udev));
        return (error);
}

SYSCTL_NODE(_hw_bus, OID_AUTO, devices, CTLFLAG_RD, sysctl_devices,
    "system device tree");

int
bus_data_generation_check(int generation)
{
        if (generation != bus_data_generation)
                return (1);

        /* XXX generate optimised lists here? */
        return (0);
}

void
bus_data_generation_update(void)
{
        bus_data_generation++;
}

const char *
intr_str_polarity(enum intr_polarity pola)
{
        switch (pola) {
        case INTR_POLARITY_LOW:
                return "low";

        case INTR_POLARITY_HIGH:
                return "high";

        case INTR_POLARITY_CONFORM:
                return "conform";
        }
        return "unknown";
}

const char *
intr_str_trigger(enum intr_trigger trig)
{
        switch (trig) {
        case INTR_TRIGGER_EDGE:
                return "edge";

        case INTR_TRIGGER_LEVEL:
                return "level";

        case INTR_TRIGGER_CONFORM:
                return "conform";
        }
        return "unknown";
}

int
device_getenv_int(device_t dev, const char *knob, int def)
{
        char env[128];

        /* Deprecated; for compat */
        ksnprintf(env, sizeof(env), "hw.%s.%s", device_get_nameunit(dev), knob);
        kgetenv_int(env, &def);

        /* Prefer dev.driver.unit.knob */
        ksnprintf(env, sizeof(env), "dev.%s.%d.%s",
            device_get_name(dev), device_get_unit(dev), knob);
        kgetenv_int(env, &def);

        return def;
}

void
device_getenv_string(device_t dev, const char *knob, char * __restrict data,
    int dlen, const char * __restrict def)
{
        char env[128];

        strlcpy(data, def, dlen);

        /* Deprecated; for compat */
        ksnprintf(env, sizeof(env), "hw.%s.%s", device_get_nameunit(dev), knob);
        kgetenv_string(env, data, dlen);

        /* Prefer dev.driver.unit.knob */
        ksnprintf(env, sizeof(env), "dev.%s.%d.%s",
            device_get_name(dev), device_get_unit(dev), knob);
        kgetenv_string(env, data, dlen);
}