/* $NetBSD: subr_autoconf.c,v 1.320 2026/03/24 13:28:06 yamt Exp $ */

/*
 * Copyright (c) 1996, 2000 Christopher G. Demetriou
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *          This product includes software developed for the
 *          NetBSD Project.  See http://www.NetBSD.org/ for
 *          information about NetBSD.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 *
 * --(license Id: LICENSE.proto,v 1.1 2000/06/13 21:40:26 cgd Exp )--
 */

/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Lawrence Berkeley Laboratories.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 * from: Header: subr_autoconf.c,v 1.12 93/02/01 19:31:48 torek Exp  (LBL)
 *
 *      @(#)subr_autoconf.c     8.3 (Berkeley) 5/17/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.320 2026/03/24 13:28:06 yamt Exp $");

#ifdef _KERNEL_OPT
#include "opt_ddb.h"
#include "drvctl.h"
#endif

#include <sys/param.h>
#include <sys/types.h>

#include <sys/buf.h>
#include <sys/callout.h>
#include <sys/conf.h>
#include <sys/cpu.h>
#include <sys/device.h>
#include <sys/device_calls.h>
#include <sys/device_impl.h>
#include <sys/devmon.h>
#include <sys/dirent.h>
#include <sys/disk.h>
#include <sys/disklabel.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/kthread.h>
#include <sys/localcount.h>
#include <sys/lockf.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/reboot.h>
#include <sys/rndsource.h>
#include <sys/sdt.h>
#include <sys/stdarg.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/unistd.h>

#include <machine/limits.h>

/*
 * Autoconfiguration subroutines.
 */

/*
 * Device autoconfiguration timings are mixed into the entropy pool.
 */
static krndsource_t rnd_autoconf_source;

/*
 * ioconf.c exports exactly two names: cfdata and cfroots.  All system
 * devices and drivers are found via these tables.
 */
extern struct cfdata cfdata[];
extern const short cfroots[];

/*
 * List of all cfdriver structures.  We use this to detect duplicates
 * when other cfdrivers are loaded.
 */
struct cfdriverlist allcfdrivers = LIST_HEAD_INITIALIZER(&allcfdrivers);
extern struct cfdriver * const cfdriver_list_initial[];

/*
 * Initial list of cfattach's.
 */
extern const struct cfattachinit cfattachinit[];

/*
 * List of all cfattach interface attributes.  Kept separately from
 * cfattaches themselves because they're extremely uncommon.
 */
static LIST_HEAD(, cfattachiattr) allcfattachiattrs =
    LIST_HEAD_INITIALIZER(allcfattachiattrs);

/*
 * List of cfdata tables.  We always have one such list -- the one
 * built statically when the kernel was configured.
 */
struct cftablelist allcftables = TAILQ_HEAD_INITIALIZER(allcftables);
static struct cftable initcftable;

#define ROOT ((device_t)NULL)

struct matchinfo {
        cfsubmatch_t fn;
        device_t parent;
        const int *locs;
        void    *aux;
        struct  cfdata *match;
        int     pri;
};

struct alldevs_foray {
        int                     af_s;
        struct devicelist       af_garbage;
};

/*
 * Internal version of the cfargs structure; all versions are
 * canonicalized to this.
 */
struct cfargs_internal {
        union {
                cfsubmatch_t    submatch;/* submatch function (direct config) */
                cfsearch_t      search;  /* search function (indirect config) */
        };
        const char *    iattr;          /* interface attribute */
        const int *     locators;       /* locators array */
        devhandle_t     devhandle;      /* devhandle_t (by value) */
};

static char *number(char *, int);
static void mapply(struct matchinfo *, cfdata_t);
static void config_devdelete(device_t);
static void config_devunlink(device_t, struct devicelist *);
static void config_makeroom(int, struct cfdriver *);
static void config_devlink(device_t);
static void config_alldevs_enter(struct alldevs_foray *);
static void config_alldevs_exit(struct alldevs_foray *);
static void config_add_attrib_dict(device_t);
static device_t config_attach_internal(device_t, cfdata_t, void *,
                    cfprint_t, const struct cfargs_internal *);

static void config_collect_garbage(struct devicelist *);
static void config_dump_garbage(struct devicelist *);

static void pmflock_debug(device_t, const char *, int);

static device_t deviter_next1(deviter_t *);
static void deviter_reinit(deviter_t *);

struct deferred_config {
        TAILQ_ENTRY(deferred_config) dc_queue;
        device_t dc_dev;
        void (*dc_func)(device_t);
};

TAILQ_HEAD(deferred_config_head, deferred_config);

static struct deferred_config_head deferred_config_queue =
        TAILQ_HEAD_INITIALIZER(deferred_config_queue);
static struct deferred_config_head interrupt_config_queue =
        TAILQ_HEAD_INITIALIZER(interrupt_config_queue);
static int interrupt_config_threads = 8;
static struct deferred_config_head mountroot_config_queue =
        TAILQ_HEAD_INITIALIZER(mountroot_config_queue);
static int mountroot_config_threads = 2;
static lwp_t **mountroot_config_lwpids;
static size_t mountroot_config_lwpids_size;
bool root_is_mounted = false;

static void config_process_deferred(struct deferred_config_head *, device_t);

/* Hooks to finalize configuration once all real devices have been found. */
struct finalize_hook {
        TAILQ_ENTRY(finalize_hook) f_list;
        int (*f_func)(device_t);
        device_t f_dev;
};
static TAILQ_HEAD(, finalize_hook) config_finalize_list =
        TAILQ_HEAD_INITIALIZER(config_finalize_list);
static int config_finalize_done;

/* list of all devices */
static struct devicelist alldevs = TAILQ_HEAD_INITIALIZER(alldevs);
static kmutex_t alldevs_lock __cacheline_aligned;
static devgen_t alldevs_gen = 1;
static int alldevs_nread = 0;
static int alldevs_nwrite = 0;
static bool alldevs_garbage = false;

static struct devicelist config_pending =
    TAILQ_HEAD_INITIALIZER(config_pending);
static kmutex_t config_misc_lock;
static kcondvar_t config_misc_cv;

static bool detachall = false;

#define STREQ(s1, s2)                   \
        (*(s1) == *(s2) && strcmp((s1), (s2)) == 0)

static bool config_initialized = false; /* config_init() has been called. */

static int config_do_twiddle;
static callout_t config_twiddle_ch;

static void sysctl_detach_setup(struct sysctllog **);

int no_devmon_insert(const char *, prop_dictionary_t);
int (*devmon_insert_vec)(const char *, prop_dictionary_t) = no_devmon_insert;

typedef int (*cfdriver_fn)(struct cfdriver *);
static int
frob_cfdrivervec(struct cfdriver * const *cfdriverv,
        cfdriver_fn drv_do, cfdriver_fn drv_undo,
        const char *style, bool dopanic)
{
        void (*pr)(const char *, ...) __printflike(1, 2) =
            dopanic ? panic : printf;
        int i, error = 0, e2 __diagused;

        for (i = 0; cfdriverv[i] != NULL; i++) {
                if ((error = drv_do(cfdriverv[i])) != 0) {
                        pr("configure: `%s' driver %s failed: %d",
                            cfdriverv[i]->cd_name, style, error);
                        goto bad;
                }
        }

        KASSERT(error == 0);
        return 0;

 bad:
        printf("\n");
        for (i--; i >= 0; i--) {
                e2 = drv_undo(cfdriverv[i]);
                KASSERT(e2 == 0);
        }

        return error;
}

typedef int (*cfattach_fn)(const char *, struct cfattach *,
    struct cfattachiattr * const *);
static int config_cfattach_attach_iattrs(const char *, struct cfattach *,
    struct cfattachiattr * const *);
static int config_cfattach_detach_iattrs(const char *, struct cfattach *,
    struct cfattachiattr * const *);
static int
frob_cfattachvec(const struct cfattachinit *cfattachv,
        cfattach_fn att_do, cfattach_fn att_undo,
        const char *style, bool dopanic)
{
        const struct cfattachinit *cfai = NULL;
        void (*pr)(const char *, ...) __printflike(1, 2) =
            dopanic ? panic : printf;
        int j = 0, error = 0, e2 __diagused;

        for (cfai = &cfattachv[0]; cfai->cfai_name != NULL; cfai++) {
                for (j = 0; cfai->cfai_list[j] != NULL; j++) {
                        if ((error = att_do(cfai->cfai_name,
                            cfai->cfai_list[j], cfai->cfai_iattrs)) != 0) {
                                pr("configure: attachment `%s' "
                                    "of `%s' driver %s failed: %d",
                                    cfai->cfai_list[j]->ca_name,
                                    cfai->cfai_name, style, error);
                                goto bad;
                        }
                }
        }

        KASSERT(error == 0);
        return 0;

 bad:
        /*
         * Rollback in reverse order.  dunno if super-important, but
         * do that anyway.  Although the code looks a little like
         * someone did a little integration (in the math sense).
         */
        printf("\n");
        if (cfai) {
                bool last;

                for (last = false; last == false; ) {
                        if (cfai == &cfattachv[0])
                                last = true;
                        for (j--; j >= 0; j--) {
                                e2 = att_undo(cfai->cfai_name,
                                    cfai->cfai_list[j], cfai->cfai_iattrs);
                                KASSERT(e2 == 0);
                        }
                        if (!last) {
                                cfai--;
                                for (j = 0; cfai->cfai_list[j] != NULL; j++)
                                        ;
                        }
                }
        }

        return error;
}

/*
 * Initialize the autoconfiguration data structures.  Normally this
 * is done by configure(), but some platforms need to do this very
 * early (to e.g. initialize the console).
 */
void
config_init(void)
{

        KASSERT(config_initialized == false);

        mutex_init(&alldevs_lock, MUTEX_DEFAULT, IPL_VM);

        mutex_init(&config_misc_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&config_misc_cv, "cfgmisc");

        callout_init(&config_twiddle_ch, CALLOUT_MPSAFE);

        frob_cfdrivervec(cfdriver_list_initial,
            config_cfdriver_attach, NULL, "bootstrap", true);
        frob_cfattachvec(cfattachinit,
            config_cfattach_attach_iattrs, NULL, "bootstrap", true);

        initcftable.ct_cfdata = cfdata;
        TAILQ_INSERT_TAIL(&allcftables, &initcftable, ct_list);

        rnd_attach_source(&rnd_autoconf_source, "autoconf", RND_TYPE_UNKNOWN,
            RND_FLAG_COLLECT_TIME);

        config_initialized = true;
}

/*
 * Init or fini drivers and attachments.  Either all or none
 * are processed (via rollback).  It would be nice if this were
 * atomic to outside consumers, but with the current state of
 * locking ...
 */
int
config_init_component(struct cfdriver * const *cfdriverv,
        const struct cfattachinit *cfattachv, struct cfdata *cfdatav)
{
        int error;

        KERNEL_LOCK(1, NULL);

        if ((error = frob_cfdrivervec(cfdriverv,
            config_cfdriver_attach, config_cfdriver_detach, "init", false))!= 0)
                goto out;
        if ((error = frob_cfattachvec(cfattachv,
            config_cfattach_attach_iattrs, config_cfattach_detach_iattrs,
            "init", false)) != 0) {
                frob_cfdrivervec(cfdriverv,
                    config_cfdriver_detach, NULL, "init rollback", true);
                goto out;
        }
        if ((error = config_cfdata_attach(cfdatav, 1)) != 0) {
                frob_cfattachvec(cfattachv,
                    config_cfattach_detach_iattrs, NULL, "init rollback", true);
                frob_cfdrivervec(cfdriverv,
                    config_cfdriver_detach, NULL, "init rollback", true);
                goto out;
        }

        /* Success!  */
        error = 0;

out:    KERNEL_UNLOCK_ONE(NULL);
        return error;
}

int
config_fini_component(struct cfdriver * const *cfdriverv,
        const struct cfattachinit *cfattachv, struct cfdata *cfdatav)
{
        int error;

        KERNEL_LOCK(1, NULL);

        if ((error = config_cfdata_detach(cfdatav)) != 0)
                goto out;
        if ((error = frob_cfattachvec(cfattachv,
            config_cfattach_detach_iattrs, config_cfattach_attach_iattrs,
            "fini", false)) != 0) {
                if (config_cfdata_attach(cfdatav, 0) != 0)
                        panic("config_cfdata fini rollback failed");
                goto out;
        }
        if ((error = frob_cfdrivervec(cfdriverv,
            config_cfdriver_detach, config_cfdriver_attach,
            "fini", false)) != 0) {
                frob_cfattachvec(cfattachv,
                    config_cfattach_attach_iattrs, NULL, "fini rollback", true);
                if (config_cfdata_attach(cfdatav, 0) != 0)
                        panic("config_cfdata fini rollback failed");
                goto out;
        }

        /* Success!  */
        error = 0;

out:    KERNEL_UNLOCK_ONE(NULL);
        return error;
}

void
config_init_mi(void)
{

        if (!config_initialized)
                config_init();

        sysctl_detach_setup(NULL);
}

void
config_deferred(device_t dev)
{

        KASSERT(KERNEL_LOCKED_P());

        config_process_deferred(&deferred_config_queue, dev);
        config_process_deferred(&interrupt_config_queue, dev);
        config_process_deferred(&mountroot_config_queue, dev);
}

static void
config_interrupts_thread(void *cookie)
{
        struct deferred_config *dc;
        device_t dev;

        mutex_enter(&config_misc_lock);
        while ((dc = TAILQ_FIRST(&interrupt_config_queue)) != NULL) {
                TAILQ_REMOVE(&interrupt_config_queue, dc, dc_queue);
                mutex_exit(&config_misc_lock);

                dev = dc->dc_dev;
                (*dc->dc_func)(dev);
                if (!device_pmf_is_registered(dev))
                        aprint_debug_dev(dev,
                            "WARNING: power management not supported\n");
                config_pending_decr(dev);
                kmem_free(dc, sizeof(*dc));

                mutex_enter(&config_misc_lock);
        }
        mutex_exit(&config_misc_lock);

        kthread_exit(0);
}

void
config_create_interruptthreads(void)
{
        int i;

        for (i = 0; i < interrupt_config_threads; i++) {
                (void)kthread_create(PRI_NONE, 0/*XXXSMP */, NULL,
                    config_interrupts_thread, NULL, NULL, "configintr");
        }
}

static void
config_mountroot_thread(void *cookie)
{
        struct deferred_config *dc;

        mutex_enter(&config_misc_lock);
        while ((dc = TAILQ_FIRST(&mountroot_config_queue)) != NULL) {
                TAILQ_REMOVE(&mountroot_config_queue, dc, dc_queue);
                mutex_exit(&config_misc_lock);

                (*dc->dc_func)(dc->dc_dev);
                kmem_free(dc, sizeof(*dc));

                mutex_enter(&config_misc_lock);
        }
        mutex_exit(&config_misc_lock);

        kthread_exit(0);
}

void
config_create_mountrootthreads(void)
{
        int i;

        if (!root_is_mounted)
                root_is_mounted = true;

        mountroot_config_lwpids_size = sizeof(mountroot_config_lwpids) *
                                       mountroot_config_threads;
        mountroot_config_lwpids = kmem_alloc(mountroot_config_lwpids_size,
                                             KM_NOSLEEP);
        KASSERT(mountroot_config_lwpids);
        for (i = 0; i < mountroot_config_threads; i++) {
                mountroot_config_lwpids[i] = 0;
                (void)kthread_create(PRI_NONE, KTHREAD_MUSTJOIN/* XXXSMP */,
                                     NULL, config_mountroot_thread, NULL,
                                     &mountroot_config_lwpids[i],
                                     "configroot");
        }
}

void
config_finalize_mountroot(void)
{
        int i, error;

        for (i = 0; i < mountroot_config_threads; i++) {
                if (mountroot_config_lwpids[i] == 0)
                        continue;

                error = kthread_join(mountroot_config_lwpids[i]);
                if (error)
                        printf("%s: thread %x joined with error %d\n",
                               __func__, i, error);
        }
        kmem_free(mountroot_config_lwpids, mountroot_config_lwpids_size);
}

/*
 * Announce device attach/detach to userland listeners.
 */

int
no_devmon_insert(const char *name, prop_dictionary_t p)
{

        return SET_ERROR(ENODEV);
}

static void
devmon_report_device(device_t dev, bool isattach)
{
        prop_dictionary_t ev, dict = device_properties(dev);
        const char *parent;
        const char *what;
        const char *where;
        device_t pdev = device_parent(dev);

        /* If currently no drvctl device, just return */
        if (devmon_insert_vec == no_devmon_insert)
                return;

        ev = prop_dictionary_create();
        if (ev == NULL)
                return;

        what = (isattach ? "device-attach" : "device-detach");
        parent = (pdev == NULL ? "root" : device_xname(pdev));
        if (prop_dictionary_get_string(dict, "location", &where)) {
                prop_dictionary_set_string(ev, "location", where);
                aprint_debug("ev: %s %s at %s in [%s]\n",
                    what, device_xname(dev), parent, where); 
        }
        if (!prop_dictionary_set_string(ev, "device", device_xname(dev)) ||
            !prop_dictionary_set_string(ev, "parent", parent)) {
                prop_object_release(ev);
                return;
        }

        if ((*devmon_insert_vec)(what, ev) != 0)
                prop_object_release(ev);
}

/*
 * Add a cfdriver to the system.
 */
int
config_cfdriver_attach(struct cfdriver *cd)
{
        struct cfdriver *lcd;

        /* Make sure this driver isn't already in the system. */
        LIST_FOREACH(lcd, &allcfdrivers, cd_list) {
                if (STREQ(lcd->cd_name, cd->cd_name))
                        return SET_ERROR(EEXIST);
        }

        LIST_INIT(&cd->cd_attach);
        LIST_INSERT_HEAD(&allcfdrivers, cd, cd_list);

        return 0;
}

/*
 * Remove a cfdriver from the system.
 */
int
config_cfdriver_detach(struct cfdriver *cd)
{
        struct alldevs_foray af;
        int i, rc = 0;

        config_alldevs_enter(&af);
        /* Make sure there are no active instances. */
        for (i = 0; i < cd->cd_ndevs; i++) {
                if (cd->cd_devs[i] != NULL) {
                        rc = SET_ERROR(EBUSY);
                        break;
                }
        }
        config_alldevs_exit(&af);

        if (rc != 0)
                return rc;

        /* ...and no attachments loaded. */
        if (LIST_EMPTY(&cd->cd_attach) == 0)
                return SET_ERROR(EBUSY);

        LIST_REMOVE(cd, cd_list);

        KASSERT(cd->cd_devs == NULL);

        return 0;
}

/*
 * Look up a cfdriver by name.
 */
struct cfdriver *
config_cfdriver_lookup(const char *name)
{
        struct cfdriver *cd;

        LIST_FOREACH(cd, &allcfdrivers, cd_list) {
                if (STREQ(cd->cd_name, name))
                        return cd;
        }

        return NULL;
}

/*
 * Add a cfattach to the specified driver.
 */
static int
config_cfattach_attach_iattrs(const char *driver, struct cfattach *ca,
    struct cfattachiattr * const *cfias)
{
        struct cfattach *lca;
        struct cfdriver *cd;

        cd = config_cfdriver_lookup(driver);
        if (cd == NULL)
                return SET_ERROR(ESRCH);

        /* Make sure this attachment isn't already on this driver. */
        LIST_FOREACH(lca, &cd->cd_attach, ca_list) {
                if (STREQ(lca->ca_name, ca->ca_name))
                        return SET_ERROR(EEXIST);
        }

        LIST_INSERT_HEAD(&cd->cd_attach, ca, ca_list);

        if (cfias != NULL) {
                struct cfattachiattr *cfia;
                for (; (cfia = *cfias) != NULL; cfias++) {
                        if (cfia->cfia_attach == ca) {
                                LIST_INSERT_HEAD(&allcfattachiattrs, cfia,
                                    cfia_list);
                        }
                }
        }

        return 0;
}

int
config_cfattach_attach(const char *driver, struct cfattach *ca)
{
        return config_cfattach_attach_iattrs(driver, ca, NULL);
}

/*
 * Remove a cfattach from the specified driver.
 */
int
config_cfattach_detach_iattrs(const char *driver, struct cfattach *ca,
    struct cfattachiattr * const *cfias __unused)
{
        struct alldevs_foray af;
        struct cfdriver *cd;
        device_t dev;
        int i, rc = 0;

        cd = config_cfdriver_lookup(driver);
        if (cd == NULL)
                return SET_ERROR(ESRCH);

        config_alldevs_enter(&af);
        /* Make sure there are no active instances. */
        for (i = 0; i < cd->cd_ndevs; i++) {
                if ((dev = cd->cd_devs[i]) == NULL)
                        continue;
                if (dev->dv_cfattach == ca) {
                        rc = SET_ERROR(EBUSY);
                        break;
                }
        }
        config_alldevs_exit(&af);

        if (rc != 0)
                return rc;

        LIST_REMOVE(ca, ca_list);

        /*
         * The cfattach is going away, so we always traverse the
         * list of cfattach iattrs and remove any that reference
         * it.  The "cfias" argument is largely due to the need
         * to have this fuction's signature match.
         */
        struct cfattachiattr *cfia, *next_cfia;
        LIST_FOREACH_SAFE(cfia, &allcfattachiattrs, cfia_list, next_cfia) {
                if (cfia->cfia_attach == ca) {
                        LIST_REMOVE(cfia, cfia_list);
                }
        }

        return 0;
}

int
config_cfattach_detach(const char *driver, struct cfattach *ca)
{
        return config_cfattach_detach_iattrs(driver, ca, NULL);
}

/*
 * Look up a cfattach by name.
 */
static struct cfattach *
config_cfattach_lookup_cd(struct cfdriver *cd, const char *atname)
{
        struct cfattach *ca;

        LIST_FOREACH(ca, &cd->cd_attach, ca_list) {
                if (STREQ(ca->ca_name, atname))
                        return ca;
        }

        return NULL;
}

/*
 * Look up a cfattach by driver/attachment name.
 */
struct cfattach *
config_cfattach_lookup(const char *name, const char *atname)
{
        struct cfdriver *cd;

        cd = config_cfdriver_lookup(name);
        if (cd == NULL)
                return NULL;

        return config_cfattach_lookup_cd(cd, atname);
}

/*
 * Apply the matching function and choose the best.  This is used
 * a few times and we want to keep the code small.
 */
static void
mapply(struct matchinfo *m, cfdata_t cf)
{
        int pri;

        if (m->fn != NULL) {
                pri = (*m->fn)(m->parent, cf, m->locs, m->aux);
        } else {
                pri = config_match(m->parent, cf, m->aux);
        }
        if (pri > m->pri) {
                m->match = cf;
                m->pri = pri;
        }
}

int
config_stdsubmatch(device_t parent, cfdata_t cf, const int *locs, void *aux)
{
        const struct cfiattrdata *ci;
        const struct cflocdesc *cl;
        int nlocs, i;

        ci = cfiattr_lookup(cfdata_ifattr(cf), parent->dv_cfdriver,
            parent->dv_cfattach);
        KASSERT(ci);
        nlocs = ci->ci_loclen;
        KASSERT(!nlocs || locs);
        for (i = 0; i < nlocs; i++) {
                cl = &ci->ci_locdesc[i];
                if (cl->cld_defaultstr != NULL &&
                    cf->cf_loc[i] == cl->cld_default)
                        continue;
                if (cf->cf_loc[i] == locs[i])
                        continue;
                return 0;
        }

        return config_match(parent, cf, aux);
}

/*
 * Helper function: check whether the driver supports the interface attribute
 * and return its descriptor structure.
 */
static const struct cfiattrdata *
cfdriver_get_iattr(const struct cfdriver *cd, const char *ia)
{
        const struct cfiattrdata * const *cpp;

        if (cd->cd_attrs == NULL)
                return 0;

        for (cpp = cd->cd_attrs; *cpp; cpp++) {
                if (STREQ((*cpp)->ci_name, ia)) {
                        /* Match. */
                        return *cpp;
                }
        }
        return 0;
}

/*
 * Like above, but for attachments.
 */
static const struct cfiattrdata *
cfattach_get_iattr(const struct cfattach *ca, const char *ia)
{
        struct cfattachiattr *cfia;

        LIST_FOREACH(cfia, &allcfattachiattrs, cfia_list) {
                if (cfia->cfia_attach == ca &&
                    STREQ(cfia->cfia_iattr->ci_name, ia)) {
                        /* Match. */
                        return cfia->cfia_iattr;
                }
        }
        return NULL;
}

/*
 * Short-hand for looking at both the cfdriver and cfattach of a
 * device for an interface attribute.
 */
static const struct cfiattrdata *
device_get_iattr(device_t dev, const char *name)
{
        const struct cfiattrdata *ia;

        ia = cfdriver_get_iattr(dev->dv_cfdriver, name);
        if (ia == NULL) {
                ia = cfattach_get_iattr(dev->dv_cfattach, name);
        }
        return ia;
}

static int __diagused
cfdriver_iattr_count(const struct cfdriver *cd)
{
        const struct cfiattrdata * const *cpp;
        int i;

        if (cd->cd_attrs == NULL)
                return 0;

        for (i = 0, cpp = cd->cd_attrs; *cpp; cpp++) {
                i++;
        }
        return i;
}

/*
 * Lookup an interface attribute description by name.
 * If the driver is given, consider only its supported attributes.
 */
const struct cfiattrdata *
cfiattr_lookup(const char *name, const struct cfdriver *cd,
    const struct cfattach *ca)
{
        const struct cfdriver *d;
        const struct cfiattrdata *ia;

        if (cd) {
                ia = cfdriver_get_iattr(cd, name);
                if (ia == NULL)
                        ia = cfattach_get_iattr(ca, name);
                return ia;
        }

        LIST_FOREACH(d, &allcfdrivers, cd_list) {
                ia = cfdriver_get_iattr(d, name);
                if (ia)
                        return ia;
        }
        return 0;
}

/*
 * Determine if `parent' is a potential parent for a device spec based
 * on `cfp'.
 */
static int
cfparent_match(const device_t parent, const struct cfparent *cfp)
{
        struct cfdriver *pcd;

        /* We don't match root nodes here. */
        if (cfp == NULL)
                return 0;

        pcd = parent->dv_cfdriver;
        KASSERT(pcd != NULL);

        /*
         * First, ensure this parent has the correct interface
         * attribute.
         */
        if (!device_get_iattr(parent, cfp->cfp_iattr))
                return 0;

        /*
         * If no specific parent device instance was specified (i.e.
         * we're attaching to the attribute only), we're done!
         */
        if (cfp->cfp_parent == NULL)
                return 1;

        /*
         * Check the parent device's name.
         */
        if (STREQ(pcd->cd_name, cfp->cfp_parent) == 0)
                return 0;       /* not the same parent */

        /*
         * Make sure the unit number matches.
         */
        if (cfp->cfp_unit == DVUNIT_ANY ||      /* wildcard */
            cfp->cfp_unit == parent->dv_unit)
                return 1;

        /* Unit numbers don't match. */
        return 0;
}

/*
 * Helper for config_cfdata_attach(): check all devices whether it could be
 * parent any attachment in the config data table passed, and rescan.
 */
static void
rescan_with_cfdata(const struct cfdata *cf)
{
        device_t d;
        const struct cfdata *cf1;
        deviter_t di;

        KASSERT(KERNEL_LOCKED_P());

        /*
         * "alldevs" is likely longer than a modules's cfdata, so make it
         * the outer loop.
         */
        for (d = deviter_first(&di, 0); d != NULL; d = deviter_next(&di)) {

                if (!(d->dv_cfattach->ca_rescan))
                        continue;

                for (cf1 = cf; cf1->cf_name; cf1++) {

                        if (!cfparent_match(d, cf1->cf_pspec))
                                continue;

                        (*d->dv_cfattach->ca_rescan)(d,
                                cfdata_ifattr(cf1), cf1->cf_loc);

                        config_deferred(d);
                }
        }
        deviter_release(&di);
}

/*
 * Attach a supplemental config data table and rescan potential
 * parent devices if required.
 */
int
config_cfdata_attach(cfdata_t cf, int scannow)
{
        struct cftable *ct;

        KERNEL_LOCK(1, NULL);

        ct = kmem_alloc(sizeof(*ct), KM_SLEEP);
        ct->ct_cfdata = cf;
        TAILQ_INSERT_TAIL(&allcftables, ct, ct_list);

        if (scannow)
                rescan_with_cfdata(cf);

        KERNEL_UNLOCK_ONE(NULL);

        return 0;
}

/*
 * Helper for config_cfdata_detach: check whether a device is
 * found through any attachment in the config data table.
 */
static int
dev_in_cfdata(device_t d, cfdata_t cf)
{
        const struct cfdata *cf1;

        for (cf1 = cf; cf1->cf_name; cf1++)
                if (d->dv_cfdata == cf1)
                        return 1;

        return 0;
}

/*
 * Detach a supplemental config data table. Detach all devices found
 * through that table (and thus keeping references to it) before.
 */
int
config_cfdata_detach(cfdata_t cf)
{
        device_t d;
        int error = 0;
        struct cftable *ct;
        deviter_t di;

        KERNEL_LOCK(1, NULL);

        for (d = deviter_first(&di, DEVITER_F_RW); d != NULL;
             d = deviter_next(&di)) {
                if (!dev_in_cfdata(d, cf))
                        continue;
                if ((error = config_detach(d, 0)) != 0)
                        break;
        }
        deviter_release(&di);
        if (error) {
                aprint_error_dev(d, "unable to detach instance\n");
                goto out;
        }

        TAILQ_FOREACH(ct, &allcftables, ct_list) {
                if (ct->ct_cfdata == cf) {
                        TAILQ_REMOVE(&allcftables, ct, ct_list);
                        kmem_free(ct, sizeof(*ct));
                        error = 0;
                        goto out;
                }
        }

        /* not found -- shouldn't happen */
        error = SET_ERROR(EINVAL);

out:    KERNEL_UNLOCK_ONE(NULL);
        return error;
}

/*
 * Invoke the "match" routine for a cfdata entry on behalf of
 * an external caller, usually a direct config "submatch" routine.
 */
int
config_match(device_t parent, cfdata_t cf, void *aux)
{
        struct cfattach *ca;

        KASSERT(KERNEL_LOCKED_P());

        ca = config_cfattach_lookup(cf->cf_name, cf->cf_atname);
        if (ca == NULL) {
                /* No attachment for this entry, oh well. */
                return 0;
        }

        return (*ca->ca_match)(parent, cf, aux);
}

/*
 * Invoke the "probe" routine for a cfdata entry on behalf of
 * an external caller, usually an indirect config "search" routine.
 */
int
config_probe(device_t parent, cfdata_t cf, void *aux)
{
        /*
         * This is currently a synonym for config_match(), but this
         * is an implementation detail; "match" and "probe" routines
         * have different behaviors.
         *
         * XXX config_probe() should return a bool, because there is
         * XXX no match score for probe -- it's either there or it's
         * XXX not, but some ports abuse the return value as a way
         * XXX to attach "critical" devices before "non-critical"
         * XXX devices.
         */
        return config_match(parent, cf, aux);
}

static struct cfargs_internal *
cfargs_canonicalize(const struct cfargs * const cfargs,
    struct cfargs_internal * const store)
{
        struct cfargs_internal *args = store;

        memset(args, 0, sizeof(*args));

        /* If none specified, are all-NULL pointers are good. */
        if (cfargs == NULL) {
                return args;
        }

        /*
         * Only one arguments version is recognized at this time.
         */
        if (cfargs->cfargs_version != CFARGS_VERSION) {
                panic("cfargs_canonicalize: unknown version %lu\n",
                    (unsigned long)cfargs->cfargs_version);
        }

        /*
         * submatch and search are mutually-exclusive.
         */
        if (cfargs->submatch != NULL && cfargs->search != NULL) {
                panic("cfargs_canonicalize: submatch and search are "
                      "mutually-exclusive");
        }
        if (cfargs->submatch != NULL) {
                args->submatch = cfargs->submatch;
        } else if (cfargs->search != NULL) {
                args->search = cfargs->search;
        }

        args->iattr = cfargs->iattr;
        args->locators = cfargs->locators;
        args->devhandle = cfargs->devhandle;

        return args;
}

/*
 * Iterate over all potential children of some device, calling the given
 * function (default being the child's match function) for each one.
 * Nonzero returns are matches; the highest value returned is considered
 * the best match.  Return the `found child' if we got a match, or NULL
 * otherwise.  The `aux' pointer is simply passed on through.
 *
 * Note that this function is designed so that it can be used to apply
 * an arbitrary function to all potential children (its return value
 * can be ignored).
 */
static cfdata_t
config_search_internal(device_t parent, void *aux,
    const struct cfargs_internal * const args)
{
        struct cftable *ct;
        cfdata_t cf;
        struct matchinfo m;

        KASSERT(config_initialized);
        KASSERTMSG((!args->iattr ||
                device_get_iattr(parent, args->iattr)),
            "%s searched for child at interface attribute %s,"
            " but device %s(4) has no such interface attribute in config(5)",
            device_xname(parent), args->iattr,
            parent->dv_cfdriver->cd_name);
        KASSERTMSG((args->iattr ||
                cfdriver_iattr_count(parent->dv_cfdriver) < 2),
            "%s searched for child without interface attribute,"
            " needed to disambiguate among the %d declared for in %s(4)"
            " in config(5)",
            device_xname(parent),
            cfdriver_iattr_count(parent->dv_cfdriver),
            parent->dv_cfdriver->cd_name);

        m.fn = args->submatch;          /* N.B. union */
        m.parent = parent;
        m.locs = args->locators;
        m.aux = aux;
        m.match = NULL;
        m.pri = 0;

        TAILQ_FOREACH(ct, &allcftables, ct_list) {
                for (cf = ct->ct_cfdata; cf->cf_name; cf++) {

                        /* We don't match root nodes here. */
                        if (!cf->cf_pspec)
                                continue;

                        /*
                         * Skip cf if no longer eligible, otherwise scan
                         * through parents for one matching `parent', and
                         * try match function.
                         */
                        if (cf->cf_fstate == FSTATE_FOUND)
                                continue;
                        if (cf->cf_fstate == FSTATE_DNOTFOUND ||
                            cf->cf_fstate == FSTATE_DSTAR)
                                continue;

                        /*
                         * If an interface attribute was specified,
                         * consider only children which attach to
                         * that attribute.
                         */
                        if (args->iattr != NULL &&
                            !STREQ(args->iattr, cfdata_ifattr(cf)))
                                continue;

                        if (cfparent_match(parent, cf->cf_pspec))
                                mapply(&m, cf);
                }
        }
        rnd_add_uint32(&rnd_autoconf_source, 0);
        return m.match;
}

cfdata_t
config_search(device_t parent, void *aux, const struct cfargs *cfargs)
{
        cfdata_t cf;
        struct cfargs_internal store;

        cf = config_search_internal(parent, aux,
            cfargs_canonicalize(cfargs, &store));

        return cf;
}

/*
 * Find the given root device.
 * This is much like config_search, but there is no parent.
 * Don't bother with multiple cfdata tables; the root node
 * must always be in the initial table.
 */
cfdata_t
config_rootsearch(cfsubmatch_t fn, const char *rootname, void *aux)
{
        cfdata_t cf;
        const short *p;
        struct matchinfo m;

        m.fn = fn;
        m.parent = ROOT;
        m.aux = aux;
        m.match = NULL;
        m.pri = 0;
        m.locs = 0;
        /*
         * Look at root entries for matching name.  We do not bother
         * with found-state here since only one root should ever be
         * searched (and it must be done first).
         */
        for (p = cfroots; *p >= 0; p++) {
                cf = &cfdata[*p];
                if (strcmp(cf->cf_name, rootname) == 0)
                        mapply(&m, cf);
        }
        return m.match;
}

static const char * const msgs[] = {
[QUIET]         =       "",
[UNCONF]        =       " not configured\n",
[UNSUPP]        =       " unsupported\n",
};

/*
 * The given `aux' argument describes a device that has been found
 * on the given parent, but not necessarily configured.  Locate the
 * configuration data for that device (using the submatch function
 * provided, or using candidates' cd_match configuration driver
 * functions) and attach it, and return its device_t.  If the device was
 * not configured, call the given `print' function and return NULL.
 */
device_t
config_found_acquire(device_t parent, void *aux, cfprint_t print,
    const struct cfargs * const cfargs)
{
        cfdata_t cf;
        struct cfargs_internal store;
        const struct cfargs_internal * const args =
            cfargs_canonicalize(cfargs, &store);
        device_t dev;

        KERNEL_LOCK(1, NULL);

        cf = config_search_internal(parent, aux, args);
        if (cf != NULL) {
                dev = config_attach_internal(parent, cf, aux, print, args);
                goto out;
        }

        if (print) {
                if (config_do_twiddle && cold)
                        twiddle();

                const int pret = (*print)(aux, device_xname(parent));
                KASSERT(pret >= 0);
                KASSERT(pret < __arraycount(msgs));
                KASSERT(msgs[pret] != NULL);
                aprint_normal("%s", msgs[pret]);
        }

        dev = NULL;

out:    KERNEL_UNLOCK_ONE(NULL);
        return dev;
}

/*
 * config_found(parent, aux, print, cfargs)
 *
 *      Legacy entry point for callers whose use of the returned
 *      device_t is not delimited by device_release.
 *
 *      The caller is required to hold the kernel lock as a fragile
 *      defence against races.
 *
 *      Callers should ignore the return value or be converted to
 *      config_found_acquire with a matching device_release once they
 *      have finished with the returned device_t.
 */
device_t
config_found(device_t parent, void *aux, cfprint_t print,
    const struct cfargs * const cfargs)
{
        device_t dev;

        KASSERT(KERNEL_LOCKED_P());

        dev = config_found_acquire(parent, aux, print, cfargs);
        if (dev == NULL)
                return NULL;
        device_release(dev);

        return dev;
}

/*
 * As above, but for root devices.
 */
device_t
config_rootfound(const char *rootname, void *aux)
{
        cfdata_t cf;
        device_t dev = NULL;

        KERNEL_LOCK(1, NULL);
        if ((cf = config_rootsearch(NULL, rootname, aux)) != NULL)
                dev = config_attach(ROOT, cf, aux, NULL, CFARGS_NONE);
        else
                aprint_error("root device %s not configured\n", rootname);
        KERNEL_UNLOCK_ONE(NULL);
        return dev;
}

/* just like sprintf(buf, "%d") except that it works from the end */
static char *
number(char *ep, int n)
{

        *--ep = 0;
        while (n >= 10) {
                *--ep = (n % 10) + '0';
                n /= 10;
        }
        *--ep = n + '0';
        return ep;
}

/*
 * Expand the size of the cd_devs array if necessary.
 *
 * The caller must hold alldevs_lock. config_makeroom() may release and
 * re-acquire alldevs_lock, so callers should re-check conditions such
 * as alldevs_nwrite == 0 and alldevs_nread == 0 when config_makeroom()
 * returns.
 */
static void
config_makeroom(int n, struct cfdriver *cd)
{
        int ondevs, nndevs;
        device_t *osp, *nsp;

        KASSERT(mutex_owned(&alldevs_lock));
        alldevs_nwrite++;

        /* XXX arithmetic overflow */
        for (nndevs = MAX(4, cd->cd_ndevs); nndevs <= n; nndevs += nndevs)
                ;

        while (n >= cd->cd_ndevs) {
                /*
                 * Need to expand the array.
                 */
                ondevs = cd->cd_ndevs;
                osp = cd->cd_devs;

                /*
                 * Release alldevs_lock around allocation, which may
                 * sleep.
                 */
                mutex_exit(&alldevs_lock);
                nsp = kmem_alloc(sizeof(device_t) * nndevs, KM_SLEEP);
                mutex_enter(&alldevs_lock);

                /*
                 * If another thread moved the array while we did
                 * not hold alldevs_lock, try again.
                 */
                if (cd->cd_devs != osp || cd->cd_ndevs != ondevs) {
                        mutex_exit(&alldevs_lock);
                        kmem_free(nsp, sizeof(device_t) * nndevs);
                        mutex_enter(&alldevs_lock);
                        continue;
                }

                memset(nsp + ondevs, 0, sizeof(device_t) * (nndevs - ondevs));
                if (ondevs != 0)
                        memcpy(nsp, cd->cd_devs, sizeof(device_t) * ondevs);

                cd->cd_ndevs = nndevs;
                cd->cd_devs = nsp;
                if (ondevs != 0) {
                        mutex_exit(&alldevs_lock);
                        kmem_free(osp, sizeof(device_t) * ondevs);
                        mutex_enter(&alldevs_lock);
                }
        }
        KASSERT(mutex_owned(&alldevs_lock));
        alldevs_nwrite--;
}

/*
 * Put dev into the devices list.
 */
static void
config_devlink(device_t dev)
{

        mutex_enter(&alldevs_lock);

        KASSERT(device_cfdriver(dev)->cd_devs[dev->dv_unit] == dev);

        dev->dv_add_gen = alldevs_gen;
        /* It is safe to add a device to the tail of the list while
         * readers and writers are in the list.
         */
        TAILQ_INSERT_TAIL(&alldevs, dev, dv_list);
        mutex_exit(&alldevs_lock);
}

static void
config_devfree(device_t dev)
{

        KASSERT(dev->dv_flags & DVF_PRIV_ALLOC);
        KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);

        if (dev->dv_cfattach->ca_devsize > 0)
                kmem_free(dev->dv_private, dev->dv_cfattach->ca_devsize);
        kmem_free(dev, sizeof(*dev));
}

/*
 * Caller must hold alldevs_lock.
 */
static void
config_devunlink(device_t dev, struct devicelist *garbage)
{
        struct device_garbage *dg = &dev->dv_garbage;
        cfdriver_t cd = device_cfdriver(dev);
        int i;

        KASSERT(mutex_owned(&alldevs_lock));
        KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);

        /* Unlink from device list.  Link to garbage list. */
        TAILQ_REMOVE(&alldevs, dev, dv_list);
        TAILQ_INSERT_TAIL(garbage, dev, dv_list);

        /* Remove from cfdriver's array. */
        cd->cd_devs[dev->dv_unit] = NULL;

        /*
         * If the device now has no units in use, unlink its softc array.
         */
        for (i = 0; i < cd->cd_ndevs; i++) {
                if (cd->cd_devs[i] != NULL)
                        break;
        }
        /* Nothing found.  Unlink, now.  Deallocate, later. */
        if (i == cd->cd_ndevs) {
                dg->dg_ndevs = cd->cd_ndevs;
                dg->dg_devs = cd->cd_devs;
                cd->cd_devs = NULL;
                cd->cd_ndevs = 0;
        }
}

static void
config_devdelete(device_t dev)
{
        struct device_garbage *dg = &dev->dv_garbage;
        device_lock_t dvl = device_getlock(dev);

        KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);

        if (dg->dg_devs != NULL)
                kmem_free(dg->dg_devs, sizeof(device_t) * dg->dg_ndevs);

        localcount_fini(dev->dv_localcount);
        kmem_free(dev->dv_localcount, sizeof(*dev->dv_localcount));

        cv_destroy(&dvl->dvl_cv);
        mutex_destroy(&dvl->dvl_mtx);

        KASSERT(dev->dv_properties != NULL);
        prop_object_release(dev->dv_properties);

        if (dev->dv_activity_handlers)
                panic("%s with registered handlers", __func__);

        if (dev->dv_locators) {
                size_t amount = *--dev->dv_locators;
                kmem_free(dev->dv_locators, amount);
        }

        config_devfree(dev);
}

static int
config_unit_nextfree(cfdriver_t cd, cfdata_t cf)
{
        int unit = cf->cf_unit;

        KASSERT(mutex_owned(&alldevs_lock));

        if (unit < 0)
                return -1;
        if (cf->cf_fstate == FSTATE_STAR) {
                for (; unit < cd->cd_ndevs; unit++)
                        if (cd->cd_devs[unit] == NULL)
                                break;
                /*
                 * unit is now the unit of the first NULL device pointer,
                 * or max(cd->cd_ndevs,cf->cf_unit).
                 */
        } else {
                if (unit < cd->cd_ndevs && cd->cd_devs[unit] != NULL)
                        unit = -1;
        }
        return unit;
}

static int
config_unit_alloc(device_t dev, cfdriver_t cd, cfdata_t cf)
{
        struct alldevs_foray af;
        int unit;

        config_alldevs_enter(&af);
        for (;;) {
                unit = config_unit_nextfree(cd, cf);
                if (unit == -1)
                        break;
                if (unit < cd->cd_ndevs) {
                        cd->cd_devs[unit] = dev;
                        dev->dv_unit = unit;
                        break;
                }
                config_makeroom(unit, cd);
        }
        config_alldevs_exit(&af);

        return unit;
}

static device_t
config_devalloc(const device_t parent, const cfdata_t cf,
    const struct cfargs_internal * const args)
{
        cfdriver_t cd;
        cfattach_t ca;
        size_t lname, lunit;
        const char *xunit;
        int myunit;
        char num[10];
        device_t dev;
        void *dev_private;
        const struct cfiattrdata *ia;
        device_lock_t dvl;

        cd = config_cfdriver_lookup(cf->cf_name);
        if (cd == NULL)
                return NULL;

        ca = config_cfattach_lookup_cd(cd, cf->cf_atname);
        if (ca == NULL)
                return NULL;

        /* get memory for all device vars */
        KASSERT(ca->ca_flags & DVF_PRIV_ALLOC);
        if (ca->ca_devsize > 0) {
                dev_private = kmem_zalloc(ca->ca_devsize, KM_SLEEP);
        } else {
                dev_private = NULL;
        }
        dev = kmem_zalloc(sizeof(*dev), KM_SLEEP);

        dev->dv_handle = args->devhandle;

        dev->dv_class = cd->cd_class;
        dev->dv_cfdata = cf;
        dev->dv_cfdriver = cd;
        dev->dv_cfattach = ca;
        dev->dv_activity_count = 0;
        dev->dv_activity_handlers = NULL;
        dev->dv_private = dev_private;
        dev->dv_flags = ca->ca_flags;   /* inherit flags from class */
        dev->dv_attaching = curlwp;

        myunit = config_unit_alloc(dev, cd, cf);
        if (myunit == -1) {
                config_devfree(dev);
                return NULL;
        }

        /* compute length of name and decimal expansion of unit number */
        lname = strlen(cd->cd_name);
        xunit = number(&num[sizeof(num)], myunit);
        lunit = &num[sizeof(num)] - xunit;
        if (lname + lunit > sizeof(dev->dv_xname))
                panic("config_devalloc: device name too long");

        dvl = device_getlock(dev);

        mutex_init(&dvl->dvl_mtx, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&dvl->dvl_cv, "pmfsusp");

        memcpy(dev->dv_xname, cd->cd_name, lname);
        memcpy(dev->dv_xname + lname, xunit, lunit);
        dev->dv_parent = parent;
        if (parent != NULL)
                dev->dv_depth = parent->dv_depth + 1;
        else
                dev->dv_depth = 0;
        dev->dv_flags |= DVF_ACTIVE;    /* always initially active */
        if (args->locators) {
                KASSERT(parent); /* no locators at root */
                ia = cfiattr_lookup(cfdata_ifattr(cf), parent->dv_cfdriver,
                    parent->dv_cfattach);
                dev->dv_locators =
                    kmem_alloc(sizeof(int) * (ia->ci_loclen + 1), KM_SLEEP);
                *dev->dv_locators++ = sizeof(int) * (ia->ci_loclen + 1);
                memcpy(dev->dv_locators, args->locators,
                    sizeof(int) * ia->ci_loclen);
        }
        dev->dv_properties = prop_dictionary_create();
        KASSERT(dev->dv_properties != NULL);

        prop_dictionary_set_string_nocopy(dev->dv_properties,
            "device-driver", dev->dv_cfdriver->cd_name);
        prop_dictionary_set_uint16(dev->dv_properties,
            "device-unit", dev->dv_unit);
        if (parent != NULL) {
                prop_dictionary_set_string(dev->dv_properties,
                    "device-parent", device_xname(parent));
        }

        dev->dv_localcount = kmem_zalloc(sizeof(*dev->dv_localcount),
            KM_SLEEP);
        localcount_init(dev->dv_localcount);

        if (dev->dv_cfdriver->cd_attrs != NULL)
                config_add_attrib_dict(dev);

        return dev;
}

/*
 * Create an array of device attach attributes and add it
 * to the device's dv_properties dictionary.
 *
 * <key>interface-attributes</key>
 * <array>
 *    <dict>
 *       <key>attribute-name</key>
 *       <string>foo</string>
 *       <key>locators</key>
 *       <array>
 *          <dict>
 *             <key>loc-name</key>
 *             <string>foo-loc1</string>
 *          </dict>
 *          <dict>
 *             <key>loc-name</key>
 *             <string>foo-loc2</string>
 *             <key>default</key>
 *             <string>foo-loc2-default</string>
 *          </dict>
 *          ...
 *       </array>
 *    </dict>
 *    ...
 * </array>
 */

static void
config_add_attrib_dict(device_t dev)
{
        int i, j;
        const struct cfiattrdata *ci;
        prop_dictionary_t attr_dict, loc_dict;
        prop_array_t attr_array, loc_array;

        if ((attr_array = prop_array_create()) == NULL)
                return;

        for (i = 0; ; i++) {
                if ((ci = dev->dv_cfdriver->cd_attrs[i]) == NULL)
                        break;
                if ((attr_dict = prop_dictionary_create()) == NULL)
                        break;
                prop_dictionary_set_string_nocopy(attr_dict, "attribute-name",
                    ci->ci_name);

                /* Create an array of the locator names and defaults */

                if (ci->ci_loclen != 0 &&
                    (loc_array = prop_array_create()) != NULL) {
                        for (j = 0; j < ci->ci_loclen; j++) {
                                loc_dict = prop_dictionary_create();
                                if (loc_dict == NULL)
                                        continue;
                                prop_dictionary_set_string_nocopy(loc_dict,
                                    "loc-name", ci->ci_locdesc[j].cld_name);
                                if (ci->ci_locdesc[j].cld_defaultstr != NULL)
                                        prop_dictionary_set_string_nocopy(
                                            loc_dict, "default",
                                            ci->ci_locdesc[j].cld_defaultstr);
                                prop_array_set(loc_array, j, loc_dict);
                                prop_object_release(loc_dict);
                        }
                        prop_dictionary_set_and_rel(attr_dict, "locators",
                            loc_array);
                }
                prop_array_add(attr_array, attr_dict);
                prop_object_release(attr_dict);
        }
        if (i == 0)
                prop_object_release(attr_array);
        else
                prop_dictionary_set_and_rel(dev->dv_properties,
                    "interface-attributes", attr_array);

        return;
}

static void
config_device_register(device_t dev, void *aux)
{
        struct device_register_args args = {
                .aux = aux,
        };

        /* We don't really care if this fails. */
        device_call(dev, DEVICE_REGISTER(&args));

        device_register(dev, aux);
}

/*
 * Attach a found device.
 *
 * Returns the device referenced, to be released with device_release.
 */
static device_t
config_attach_internal(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
    const struct cfargs_internal * const args)
{
        device_t dev;
        struct cftable *ct;
        const char *drvname;
        bool deferred;

        KASSERT(KERNEL_LOCKED_P());

        dev = config_devalloc(parent, cf, args);
        if (!dev)
                panic("config_attach: allocation of device softc failed");

        /* XXX redundant - see below? */
        if (cf->cf_fstate != FSTATE_STAR) {
                KASSERT(cf->cf_fstate == FSTATE_NOTFOUND);
                cf->cf_fstate = FSTATE_FOUND;
        }

        config_devlink(dev);

        if (config_do_twiddle && cold)
                twiddle();
        else
                aprint_naive("Found ");
        /*
         * We want the next two printfs for normal, verbose, and quiet,
         * but not silent (in which case, we're twiddling, instead).
         */
        if (parent == ROOT) {
                aprint_naive("%s (root)", device_xname(dev));
                aprint_normal("%s (root)", device_xname(dev));
        } else {
                aprint_naive("%s at %s", device_xname(dev),
                    device_xname(parent));
                aprint_normal("%s at %s", device_xname(dev),
                    device_xname(parent));
                if (print)
                        (void) (*print)(aux, NULL);
        }

        /*
         * Before attaching, clobber any unfound devices that are
         * otherwise identical.
         * XXX code above is redundant?
         */
        drvname = dev->dv_cfdriver->cd_name;
        TAILQ_FOREACH(ct, &allcftables, ct_list) {
                for (cf = ct->ct_cfdata; cf->cf_name; cf++) {
                        if (STREQ(cf->cf_name, drvname) &&
                            cf->cf_unit == dev->dv_unit) {
                                if (cf->cf_fstate == FSTATE_NOTFOUND)
                                        cf->cf_fstate = FSTATE_FOUND;
                        }
                }
        }
        config_device_register(dev, aux);

        /* Let userland know */
        devmon_report_device(dev, true);

        /*
         * Prevent detach until the driver's attach function, and all
         * deferred actions, have finished.
         */
        config_pending_incr(dev);

        /*
         * Prevent concurrent detach from destroying the device_t until
         * the caller has released the device.
         */
        device_acquire(dev);

        /* Call the driver's attach function.  */
        (*dev->dv_cfattach->ca_attach)(parent, dev, aux);

        /*
         * Allow other threads to acquire references to the device now
         * that the driver's attach function is done.
         */
        mutex_enter(&config_misc_lock);
        KASSERT(dev->dv_attaching == curlwp);
        dev->dv_attaching = NULL;
        cv_broadcast(&config_misc_cv);
        mutex_exit(&config_misc_lock);

        /*
         * Synchronous parts of attach are done.  Allow detach, unless
         * the driver's attach function scheduled deferred actions.
         */
        config_pending_decr(dev);

        mutex_enter(&config_misc_lock);
        deferred = (dev->dv_pending != 0);
        mutex_exit(&config_misc_lock);

        if (!deferred && !device_pmf_is_registered(dev))
                aprint_debug_dev(dev,
                    "WARNING: power management not supported\n");

        config_process_deferred(&deferred_config_queue, dev);

        device_register_post_config(dev, aux);
        rnd_add_uint32(&rnd_autoconf_source, 0);
        return dev;
}

device_t
config_attach_acquire(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
    const struct cfargs *cfargs)
{
        struct cfargs_internal store;
        device_t dev;

        KERNEL_LOCK(1, NULL);
        dev = config_attach_internal(parent, cf, aux, print,
            cfargs_canonicalize(cfargs, &store));
        KERNEL_UNLOCK_ONE(NULL);

        return dev;
}

/*
 * config_attach(parent, cf, aux, print, cfargs)
 *
 *      Legacy entry point for callers whose use of the returned
 *      device_t is not delimited by device_release.
 *
 *      The caller is required to hold the kernel lock as a fragile
 *      defence against races.
 *
 *      Callers should ignore the return value or be converted to
 *      config_attach_acquire with a matching device_release once they
 *      have finished with the returned device_t.
 */
device_t
config_attach(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
    const struct cfargs *cfargs)
{
        device_t dev;

        KASSERT(KERNEL_LOCKED_P());

        dev = config_attach_acquire(parent, cf, aux, print, cfargs);
        if (dev == NULL)
                return NULL;
        device_release(dev);

        return dev;
}

/*
 * As above, but for pseudo-devices.  Pseudo-devices attached in this
 * way are silently inserted into the device tree, and their children
 * attached.
 *
 * Note that because pseudo-devices are attached silently, any information
 * the attach routine wishes to print should be prefixed with the device
 * name by the attach routine.
 */
device_t
config_attach_pseudo_acquire(cfdata_t cf, void *aux)
{
        device_t dev;

        KERNEL_LOCK(1, NULL);

        struct cfargs_internal args = { };
        dev = config_devalloc(ROOT, cf, &args);
        if (!dev)
                goto out;

        /* XXX mark busy in cfdata */

        if (cf->cf_fstate != FSTATE_STAR) {
                KASSERT(cf->cf_fstate == FSTATE_NOTFOUND);
                cf->cf_fstate = FSTATE_FOUND;
        }

        config_devlink(dev);

#if 0   /* XXXJRT not yet */
        config_device_register(dev, NULL);      /* like a root node */
#endif

        /* Let userland know */
        devmon_report_device(dev, true);

        /*
         * Prevent detach until the driver's attach function, and all
         * deferred actions, have finished.
         */
        config_pending_incr(dev);

        /*
         * Prevent concurrent detach from destroying the device_t until
         * the caller has released the device.
         */
        device_acquire(dev);

        /* Call the driver's attach function.  */
        (*dev->dv_cfattach->ca_attach)(ROOT, dev, aux);

        /*
         * Allow other threads to acquire references to the device now
         * that the driver's attach function is done.
         */
        mutex_enter(&config_misc_lock);
        KASSERT(dev->dv_attaching == curlwp);
        dev->dv_attaching = NULL;
        cv_broadcast(&config_misc_cv);
        mutex_exit(&config_misc_lock);

        /*
         * Synchronous parts of attach are done.  Allow detach, unless
         * the driver's attach function scheduled deferred actions.
         */
        config_pending_decr(dev);

        config_process_deferred(&deferred_config_queue, dev);

out:    KERNEL_UNLOCK_ONE(NULL);
        return dev;
}

/*
 * config_attach_pseudo(cf)
 *
 *      Legacy entry point for callers whose use of the returned
 *      device_t is not delimited by device_release.
 *
 *      The caller is required to hold the kernel lock as a fragile
 *      defence against races.
 *
 *      Callers should ignore the return value or be converted to
 *      config_attach_pseudo_acquire with a matching device_release
 *      once they have finished with the returned device_t.  As a
 *      bonus, config_attach_pseudo_acquire can pass a non-null aux
 *      argument into the driver's attach routine.
 */
device_t
config_attach_pseudo(cfdata_t cf)
{
        device_t dev;

        dev = config_attach_pseudo_acquire(cf, NULL);
        if (dev == NULL)
                return dev;
        device_release(dev);

        return dev;
}

/*
 * Caller must hold alldevs_lock.
 */
static void
config_collect_garbage(struct devicelist *garbage)
{
        device_t dv;

        KASSERT(!cpu_intr_p());
        KASSERT(!cpu_softintr_p());
        KASSERT(mutex_owned(&alldevs_lock));

        while (alldevs_nwrite == 0 && alldevs_nread == 0 && alldevs_garbage) {
                TAILQ_FOREACH(dv, &alldevs, dv_list) {
                        if (dv->dv_del_gen != 0)
                                break;
                }
                if (dv == NULL) {
                        alldevs_garbage = false;
                        break;
                }
                config_devunlink(dv, garbage);
        }
        KASSERT(mutex_owned(&alldevs_lock));
}

static void
config_dump_garbage(struct devicelist *garbage)
{
        device_t dv;

        while ((dv = TAILQ_FIRST(garbage)) != NULL) {
                TAILQ_REMOVE(garbage, dv, dv_list);
                config_devdelete(dv);
        }
}

static int
config_detach_enter(device_t dev)
{
        struct lwp *l __diagused;
        int error = 0;

        mutex_enter(&config_misc_lock);

        /*
         * Wait until attach has fully completed, and until any
         * concurrent detach (e.g., drvctl racing with USB event
         * thread) has completed.
         *
         * Caller must hold alldevs_nread or alldevs_nwrite (e.g., via
         * deviter) to ensure the winner of the race doesn't free the
         * device leading the loser of the race into use-after-free.
         *
         * XXX Not all callers do this!
         */
        while (dev->dv_pending || dev->dv_detaching) {
                KASSERTMSG(dev->dv_detaching != curlwp,
                    "recursively detaching %s", device_xname(dev));
                error = cv_wait_sig(&config_misc_cv, &config_misc_lock);
                if (error)
                        goto out;
        }

        /*
         * Attach has completed, and no other concurrent detach is
         * running.  Claim the device for detaching.  This will cause
         * all new attempts to acquire references to block.
         */
        KASSERTMSG((l = dev->dv_attaching) == NULL,
            "lwp %ld [%s] @ %p attaching %s",
            (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
            device_xname(dev));
        KASSERTMSG((l = dev->dv_detaching) == NULL,
            "lwp %ld [%s] @ %p detaching %s",
            (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
            device_xname(dev));
        dev->dv_detaching = curlwp;

out:    mutex_exit(&config_misc_lock);
        return error;
}

static void
config_detach_exit(device_t dev)
{
        struct lwp *l __diagused;

        mutex_enter(&config_misc_lock);
        KASSERTMSG(dev->dv_detaching != NULL, "not detaching %s",
            device_xname(dev));
        KASSERTMSG((l = dev->dv_detaching) == curlwp,
            "lwp %ld [%s] @ %p detaching %s",
            (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
            device_xname(dev));
        dev->dv_detaching = NULL;
        cv_broadcast(&config_misc_cv);
        mutex_exit(&config_misc_lock);
}

/*
 * Detach a device.  Optionally forced (e.g. because of hardware
 * removal) and quiet.  Returns zero if successful, non-zero
 * (an error code) otherwise.
 *
 * Note that this code wants to be run from a process context, so
 * that the detach can sleep to allow processes which have a device
 * open to run and unwind their stacks.
 *
 * Caller must hold a reference with device_acquire or
 * device_lookup_acquire.
 */
int
config_detach_release(device_t dev, int flags)
{
        struct alldevs_foray af;
        struct cftable *ct;
        cfdata_t cf;
        const struct cfattach *ca;
        struct cfdriver *cd;
        device_t d __diagused;
        int rv = 0;

        KERNEL_LOCK(1, NULL);

        cf = dev->dv_cfdata;
        KASSERTMSG((cf == NULL || cf->cf_fstate == FSTATE_FOUND ||
                cf->cf_fstate == FSTATE_STAR),
            "config_detach: %s: bad device fstate: %d",
            device_xname(dev), cf ? cf->cf_fstate : -1);

        cd = dev->dv_cfdriver;
        KASSERT(cd != NULL);

        ca = dev->dv_cfattach;
        KASSERT(ca != NULL);

        /*
         * Only one detach at a time, please -- and not until fully
         * attached.
         */
        rv = config_detach_enter(dev);
        device_release(dev);
        if (rv) {
                KERNEL_UNLOCK_ONE(NULL);
                return rv;
        }

        mutex_enter(&alldevs_lock);
        if (dev->dv_del_gen != 0) {
                mutex_exit(&alldevs_lock);
#ifdef DIAGNOSTIC
                printf("%s: %s is already detached\n", __func__,
                    device_xname(dev));
#endif /* DIAGNOSTIC */
                config_detach_exit(dev);
                KERNEL_UNLOCK_ONE(NULL);
                return SET_ERROR(ENOENT);
        }
        alldevs_nwrite++;
        mutex_exit(&alldevs_lock);

        /*
         * Call the driver's .ca_detach function, unless it has none or
         * we are skipping it because it's unforced shutdown time and
         * the driver didn't ask to detach on shutdown.
         */
        if (!detachall &&
            (flags & (DETACH_SHUTDOWN|DETACH_FORCE)) == DETACH_SHUTDOWN &&
            (dev->dv_flags & DVF_DETACH_SHUTDOWN) == 0) {
                rv = SET_ERROR(EOPNOTSUPP);
        } else if (ca->ca_detach != NULL) {
                rv = (*ca->ca_detach)(dev, flags);
        } else
                rv = SET_ERROR(EOPNOTSUPP);

        KASSERTMSG(!dev->dv_detach_done, "%s detached twice, error=%d",
            device_xname(dev), rv);

        /*
         * If it was not possible to detach the device, then we either
         * panic() (for the forced but failed case), or return an error.
         */
        if (rv) {
                /*
                 * Detach failed -- likely EOPNOTSUPP or EBUSY.  Driver
                 * must not have called config_detach_commit.
                 */
                KASSERTMSG(!dev->dv_detach_committed,
                    "%s committed to detaching and then backed out, error=%d",
                    device_xname(dev), rv);
                if (flags & DETACH_FORCE) {
                        panic("config_detach: forced detach of %s failed (%d)",
                            device_xname(dev), rv);
                }
                goto out;
        }

        /*
         * The device has now been successfully detached.
         */
        dev->dv_detach_done = true;

        /*
         * If .ca_detach didn't commit to detach, then do that for it.
         * This wakes any pending device_lookup_acquire calls so they
         * will fail.
         */
        config_detach_commit(dev);

        /*
         * If it was possible to detach the device, ensure that the
         * device is deactivated.
         */
        dev->dv_flags &= ~DVF_ACTIVE; /* XXXSMP */

        /*
         * Wait for all device_lookup_acquire references -- mostly, for
         * all attempts to open the device -- to drain.  It is the
         * responsibility of .ca_detach to ensure anything with open
         * references will be interrupted and release them promptly,
         * not block indefinitely.  All new attempts to acquire
         * references will fail, as config_detach_commit has arranged
         * by now.
         */
        mutex_enter(&config_misc_lock);
        localcount_drain(dev->dv_localcount,
            &config_misc_cv, &config_misc_lock);
        mutex_exit(&config_misc_lock);

        /* Let userland know */
        devmon_report_device(dev, false);

#ifdef DIAGNOSTIC
        /*
         * Sanity: If you're successfully detached, you should have no
         * children.  (Note that because children must be attached
         * after parents, we only need to search the latter part of
         * the list.)
         */
        mutex_enter(&alldevs_lock);
        for (d = TAILQ_NEXT(dev, dv_list); d != NULL;
            d = TAILQ_NEXT(d, dv_list)) {
                if (d->dv_parent == dev && d->dv_del_gen == 0) {
                        printf("config_detach: detached device %s"
                            " has children %s\n", device_xname(dev),
                            device_xname(d));
                        panic("config_detach");
                }
        }
        mutex_exit(&alldevs_lock);
#endif

        /* notify the parent that the child is gone */
        if (dev->dv_parent) {
                device_t p = dev->dv_parent;
                if (p->dv_cfattach->ca_childdetached)
                        (*p->dv_cfattach->ca_childdetached)(p, dev);
        }

        /*
         * Mark cfdata to show that the unit can be reused, if possible.
         */
        TAILQ_FOREACH(ct, &allcftables, ct_list) {
                for (cf = ct->ct_cfdata; cf->cf_name; cf++) {
                        if (STREQ(cf->cf_name, cd->cd_name)) {
                                if (cf->cf_fstate == FSTATE_FOUND &&
                                    cf->cf_unit == dev->dv_unit)
                                        cf->cf_fstate = FSTATE_NOTFOUND;
                        }
                }
        }

        if (dev->dv_cfdata != NULL && (flags & DETACH_QUIET) == 0)
                aprint_normal_dev(dev, "detached\n");

out:
        config_detach_exit(dev);

        config_alldevs_enter(&af);
        KASSERT(alldevs_nwrite != 0);
        --alldevs_nwrite;
        if (rv == 0 && dev->dv_del_gen == 0) {
                if (alldevs_nwrite == 0 && alldevs_nread == 0)
                        config_devunlink(dev, &af.af_garbage);
                else {
                        dev->dv_del_gen = alldevs_gen;
                        alldevs_garbage = true;
                }
        }
        config_alldevs_exit(&af);

        KERNEL_UNLOCK_ONE(NULL);

        return rv;
}

/*
 * config_detach(dev, flags)
 *
 *      Legacy entry point for callers that have not acquired a
 *      reference to dev.
 *
 *      The caller is required to hold the kernel lock as a fragile
 *      defence against races.
 *
 *      Callers should be converted to use device_acquire under a lock
 *      taken also by .ca_childdetached to synchronize access to the
 *      device_t, and then config_detach_release ouside the lock.
 *      Alternatively, most drivers detach children only in their own
 *      detach routines, which can be done with config_detach_children
 *      instead.
 */
int
config_detach(device_t dev, int flags)
{

        device_acquire(dev);
        return config_detach_release(dev, flags);
}

/*
 * config_detach_commit(dev)
 *
 *      Issued by a driver's .ca_detach routine to notify anyone
 *      waiting in device_lookup_acquire that the driver is committed
 *      to detaching the device, which allows device_lookup_acquire to
 *      wake up and fail immediately.
 *
 *      Safe to call multiple times -- idempotent.  Must be called
 *      during config_detach_enter/exit.  Safe to use with
 *      device_lookup because the device is not actually removed from
 *      the table until after config_detach_exit.
 */
void
config_detach_commit(device_t dev)
{
        struct lwp *l __diagused;

        mutex_enter(&config_misc_lock);
        KASSERTMSG(dev->dv_detaching != NULL, "not detaching %s",
            device_xname(dev));
        KASSERTMSG((l = dev->dv_detaching) == curlwp,
            "lwp %ld [%s] @ %p detaching %s",
            (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
            device_xname(dev));
        dev->dv_detach_committed = true;
        cv_broadcast(&config_misc_cv);
        mutex_exit(&config_misc_lock);
}

int
config_detach_children(device_t parent, int flags)
{
        device_t dv;
        deviter_t di;
        int error = 0;

        KASSERT(KERNEL_LOCKED_P());

        for (dv = deviter_first(&di, DEVITER_F_RW); dv != NULL;
             dv = deviter_next(&di)) {
                if (device_parent(dv) != parent)
                        continue;
                if ((error = config_detach(dv, flags)) != 0)
                        break;
        }
        deviter_release(&di);
        return error;
}

device_t
shutdown_first(struct shutdown_state *s)
{
        if (!s->initialized) {
                deviter_init(&s->di, DEVITER_F_SHUTDOWN|DEVITER_F_LEAVES_FIRST);
                s->initialized = true;
        }
        return shutdown_next(s);
}

device_t
shutdown_next(struct shutdown_state *s)
{
        device_t dv;

        while ((dv = deviter_next(&s->di)) != NULL && !device_is_active(dv))
                ;

        if (dv == NULL)
                s->initialized = false;

        return dv;
}

bool
config_detach_all(int how)
{
        static struct shutdown_state s;
        device_t curdev;
        bool progress = false;
        int flags;

        KERNEL_LOCK(1, NULL);

        if ((how & (RB_NOSYNC|RB_DUMP)) != 0)
                goto out;

        if ((how & RB_POWERDOWN) == RB_POWERDOWN)
                flags = DETACH_SHUTDOWN | DETACH_POWEROFF;
        else
                flags = DETACH_SHUTDOWN;

        for (curdev = shutdown_first(&s); curdev != NULL;
             curdev = shutdown_next(&s)) {
                aprint_debug(" detaching %s, ", device_xname(curdev));
                if (config_detach(curdev, flags) == 0) {
                        progress = true;
                        aprint_debug("success.");
                } else
                        aprint_debug("failed.");
        }

out:    KERNEL_UNLOCK_ONE(NULL);
        return progress;
}

static bool
device_is_ancestor_of(device_t ancestor, device_t descendant)
{
        device_t dv;

        for (dv = descendant; dv != NULL; dv = device_parent(dv)) {
                if (device_parent(dv) == ancestor)
                        return true;
        }
        return false;
}

int
config_deactivate(device_t dev)
{
        deviter_t di;
        const struct cfattach *ca;
        device_t descendant;
        int s, rv = 0, oflags;

        for (descendant = deviter_first(&di, DEVITER_F_ROOT_FIRST);
             descendant != NULL;
             descendant = deviter_next(&di)) {
                if (dev != descendant &&
                    !device_is_ancestor_of(dev, descendant))
                        continue;

                if ((descendant->dv_flags & DVF_ACTIVE) == 0)
                        continue;

                ca = descendant->dv_cfattach;
                oflags = descendant->dv_flags;

                descendant->dv_flags &= ~DVF_ACTIVE;
                if (ca->ca_activate == NULL)
                        continue;
                s = splhigh();
                rv = (*ca->ca_activate)(descendant, DVACT_DEACTIVATE);
                splx(s);
                if (rv != 0)
                        descendant->dv_flags = oflags;
        }
        deviter_release(&di);
        return rv;
}

/*
 * Defer the configuration of the specified device until all
 * of its parent's devices have been attached.
 */
void
config_defer(device_t dev, void (*func)(device_t))
{
        struct deferred_config *dc;

        if (dev->dv_parent == NULL)
                panic("config_defer: can't defer config of a root device");

        dc = kmem_alloc(sizeof(*dc), KM_SLEEP);

        config_pending_incr(dev);

        mutex_enter(&config_misc_lock);
#ifdef DIAGNOSTIC
        struct deferred_config *odc;
        TAILQ_FOREACH(odc, &deferred_config_queue, dc_queue) {
                if (odc->dc_dev == dev)
                        panic("config_defer: deferred twice");
        }
#endif
        dc->dc_dev = dev;
        dc->dc_func = func;
        TAILQ_INSERT_TAIL(&deferred_config_queue, dc, dc_queue);
        mutex_exit(&config_misc_lock);
}

/*
 * Defer some autoconfiguration for a device until after interrupts
 * are enabled.
 */
void
config_interrupts(device_t dev, void (*func)(device_t))
{
        struct deferred_config *dc;

        /*
         * If interrupts are enabled, callback now.
         */
        if (cold == 0) {
                (*func)(dev);
                return;
        }

        dc = kmem_alloc(sizeof(*dc), KM_SLEEP);

        config_pending_incr(dev);

        mutex_enter(&config_misc_lock);
#ifdef DIAGNOSTIC
        struct deferred_config *odc;
        TAILQ_FOREACH(odc, &interrupt_config_queue, dc_queue) {
                if (odc->dc_dev == dev)
                        panic("config_interrupts: deferred twice");
        }
#endif
        dc->dc_dev = dev;
        dc->dc_func = func;
        TAILQ_INSERT_TAIL(&interrupt_config_queue, dc, dc_queue);
        mutex_exit(&config_misc_lock);
}

/*
 * Defer some autoconfiguration for a device until after root file system
 * is mounted (to load firmware etc).
 */
void
config_mountroot(device_t dev, void (*func)(device_t))
{
        struct deferred_config *dc;

        /*
         * If root file system is mounted, callback now.
         */
        if (root_is_mounted) {
                (*func)(dev);
                return;
        }

        dc = kmem_alloc(sizeof(*dc), KM_SLEEP);

        mutex_enter(&config_misc_lock);
#ifdef DIAGNOSTIC
        struct deferred_config *odc;
        TAILQ_FOREACH(odc, &mountroot_config_queue, dc_queue) {
                if (odc->dc_dev == dev)
                        panic("%s: deferred twice", __func__);
        }
#endif

        dc->dc_dev = dev;
        dc->dc_func = func;
        TAILQ_INSERT_TAIL(&mountroot_config_queue, dc, dc_queue);
        mutex_exit(&config_misc_lock);
}

/*
 * Process a deferred configuration queue.
 */
static void
config_process_deferred(struct deferred_config_head *queue, device_t parent)
{
        struct deferred_config *dc;

        KASSERT(KERNEL_LOCKED_P());

        mutex_enter(&config_misc_lock);
        dc = TAILQ_FIRST(queue);
        while (dc) {
                if (parent == NULL || dc->dc_dev->dv_parent == parent) {
                        TAILQ_REMOVE(queue, dc, dc_queue);
                        mutex_exit(&config_misc_lock);

                        (*dc->dc_func)(dc->dc_dev);
                        config_pending_decr(dc->dc_dev);
                        kmem_free(dc, sizeof(*dc));

                        mutex_enter(&config_misc_lock);
                        /* Restart, queue might have changed */
                        dc = TAILQ_FIRST(queue);
                } else {
                        dc = TAILQ_NEXT(dc, dc_queue);
                }
        }
        mutex_exit(&config_misc_lock);
}

/*
 * Manipulate the config_pending semaphore.
 */
void
config_pending_incr(device_t dev)
{

        mutex_enter(&config_misc_lock);
        KASSERTMSG(dev->dv_pending < INT_MAX,
            "%s: excess config_pending_incr", device_xname(dev));
        if (dev->dv_pending++ == 0)
                TAILQ_INSERT_TAIL(&config_pending, dev, dv_pending_list);
#ifdef DEBUG_AUTOCONF
        printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
#endif
        mutex_exit(&config_misc_lock);
}

void
config_pending_decr(device_t dev)
{

        mutex_enter(&config_misc_lock);
        KASSERTMSG(dev->dv_pending > 0,
            "%s: excess config_pending_decr", device_xname(dev));
        if (--dev->dv_pending == 0) {
                TAILQ_REMOVE(&config_pending, dev, dv_pending_list);
                cv_broadcast(&config_misc_cv);
        }
#ifdef DEBUG_AUTOCONF
        printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
#endif
        mutex_exit(&config_misc_lock);
}

/*
 * Register a "finalization" routine.  Finalization routines are
 * called iteratively once all real devices have been found during
 * autoconfiguration, for as long as any one finalizer has done
 * any work.
 */
int
config_finalize_register(device_t dev, int (*fn)(device_t))
{
        struct finalize_hook *f;
        int error = 0;

        KERNEL_LOCK(1, NULL);

        /*
         * If finalization has already been done, invoke the
         * callback function now.
         */
        if (config_finalize_done) {
                while ((*fn)(dev) != 0)
                        /* loop */ ;
                goto out;
        }

        /* Ensure this isn't already on the list. */
        TAILQ_FOREACH(f, &config_finalize_list, f_list) {
                if (f->f_func == fn && f->f_dev == dev) {
                        error = SET_ERROR(EEXIST);
                        goto out;
                }
        }

        f = kmem_alloc(sizeof(*f), KM_SLEEP);
        f->f_func = fn;
        f->f_dev = dev;
        TAILQ_INSERT_TAIL(&config_finalize_list, f, f_list);

        /* Success!  */
        error = 0;

out:    KERNEL_UNLOCK_ONE(NULL);
        return error;
}

void
config_finalize(void)
{
        struct finalize_hook *f;
        struct pdevinit *pdev;
        extern struct pdevinit pdevinit[];
        unsigned t0 = getticks();
        int errcnt, rv;

        /*
         * Now that device driver threads have been created, wait for
         * them to finish any deferred autoconfiguration.
         */
        mutex_enter(&config_misc_lock);
        while (!TAILQ_EMPTY(&config_pending)) {
                const unsigned t1 = getticks();

                if (t1 - t0 >= hz) {
                        void (*pr)(const char *, ...) __printflike(1,2);
                        device_t dev;

                        if (t1 - t0 >= 60*hz) {
                                pr = aprint_normal;
                                t0 = t1;
                        } else {
                                pr = aprint_debug;
                        }

                        (*pr)("waiting for devices:");
                        TAILQ_FOREACH(dev, &config_pending, dv_pending_list)
                                (*pr)(" %s", device_xname(dev));
                        (*pr)("\n");
                }

                (void)cv_timedwait(&config_misc_cv, &config_misc_lock,
                    mstohz(1000));
        }
        mutex_exit(&config_misc_lock);

        KERNEL_LOCK(1, NULL);

        /* Attach pseudo-devices. */
        for (pdev = pdevinit; pdev->pdev_attach != NULL; pdev++)
                (*pdev->pdev_attach)(pdev->pdev_count);

        /* Run the hooks until none of them does any work. */
        do {
                rv = 0;
                TAILQ_FOREACH(f, &config_finalize_list, f_list)
                        rv |= (*f->f_func)(f->f_dev);
        } while (rv != 0);

        config_finalize_done = 1;

        /* Now free all the hooks. */
        while ((f = TAILQ_FIRST(&config_finalize_list)) != NULL) {
                TAILQ_REMOVE(&config_finalize_list, f, f_list);
                kmem_free(f, sizeof(*f));
        }

        KERNEL_UNLOCK_ONE(NULL);

        errcnt = aprint_get_error_count();
        if ((boothowto & (AB_QUIET|AB_SILENT)) != 0 &&
            (boothowto & AB_VERBOSE) == 0) {
                mutex_enter(&config_misc_lock);
                if (config_do_twiddle) {
                        config_do_twiddle = 0;
                        printf_nolog(" done.\n");
                }
                mutex_exit(&config_misc_lock);
        }
        if (errcnt != 0) {
                printf("WARNING: %d error%s while detecting hardware; "
                    "check system log.\n", errcnt,
                    errcnt == 1 ? "" : "s");
        }
}

void
config_twiddle_init(void)
{

        if ((boothowto & (AB_SILENT|AB_VERBOSE)) == AB_SILENT) {
                config_do_twiddle = 1;
        }
        callout_setfunc(&config_twiddle_ch, config_twiddle_fn, NULL);
}

void
config_twiddle_fn(void *cookie)
{

        mutex_enter(&config_misc_lock);
        if (config_do_twiddle) {
                twiddle();
                callout_schedule(&config_twiddle_ch, mstohz(100));
        }
        mutex_exit(&config_misc_lock);
}

static void
config_alldevs_enter(struct alldevs_foray *af)
{
        TAILQ_INIT(&af->af_garbage);
        mutex_enter(&alldevs_lock);
        config_collect_garbage(&af->af_garbage);
}

static void
config_alldevs_exit(struct alldevs_foray *af)
{
        mutex_exit(&alldevs_lock);
        config_dump_garbage(&af->af_garbage);
}

/*
 * device_lookup:
 *
 *      Look up a device instance for a given driver.
 *
 *      Caller is responsible for ensuring the device's state is
 *      stable, either by holding a reference already obtained with
 *      device_lookup_acquire or by otherwise ensuring the device is
 *      attached and can't be detached (e.g., holding an open device
 *      node and ensuring *_detach calls vdevgone).
 *
 *      XXX Find a way to assert this.
 *
 *      Safe for use up to and including interrupt context at IPL_VM.
 *      Never sleeps.
 */
device_t
device_lookup(cfdriver_t cd, int unit)
{
        device_t dv;

        mutex_enter(&alldevs_lock);
        if (unit < 0 || unit >= cd->cd_ndevs)
                dv = NULL;
        else if ((dv = cd->cd_devs[unit]) != NULL && dv->dv_del_gen != 0)
                dv = NULL;
        mutex_exit(&alldevs_lock);

        return dv;
}

/*
 * device_lookup_private:
 *
 *      Look up a softc instance for a given driver.
 */
void *
device_lookup_private(cfdriver_t cd, int unit)
{

        return device_private(device_lookup(cd, unit));
}

/*
 * device_lookup_acquire:
 *
 *      Look up a device instance for a given driver, and return a
 *      reference to it that must be released by device_release.
 *
 *      => If the device is still attaching, blocks until *_attach has
 *         returned.
 *
 *      => If the device is detaching, blocks until *_detach has
 *         returned.  May succeed or fail in that case, depending on
 *         whether *_detach has backed out (EBUSY) or committed to
 *         detaching.
 *
 *      May sleep.
 */
device_t
device_lookup_acquire(cfdriver_t cd, int unit)
{
        device_t dv;

        ASSERT_SLEEPABLE();

        /* XXX This should have a pserialized fast path -- TBD.  */
        mutex_enter(&config_misc_lock);
        mutex_enter(&alldevs_lock);
retry:  if (unit < 0 || unit >= cd->cd_ndevs ||
            (dv = cd->cd_devs[unit]) == NULL ||
            dv->dv_del_gen != 0 ||
            dv->dv_detach_committed) {
                dv = NULL;
        } else {
                /*
                 * Wait for the device to stabilize, if attaching or
                 * detaching.  Either way we must wait for *_attach or
                 * *_detach to complete, and either way we must retry:
                 * even if detaching, *_detach might fail (EBUSY) so
                 * the device may still be there.
                 */
                if ((dv->dv_attaching != NULL && dv->dv_attaching != curlwp) ||
                    dv->dv_detaching != NULL) {
                        mutex_exit(&alldevs_lock);
                        cv_wait(&config_misc_cv, &config_misc_lock);
                        mutex_enter(&alldevs_lock);
                        goto retry;
                }
                device_acquire(dv);
        }
        mutex_exit(&alldevs_lock);
        mutex_exit(&config_misc_lock);

        return dv;
}

/*
 * device_acquire:
 *
 *      Acquire a reference to a device.  It is the caller's
 *      responsibility to ensure that the device's .ca_detach routine
 *      cannot return before calling this.  Caller must release the
 *      reference with device_release or config_detach_release.
 */
void
device_acquire(device_t dv)
{

        /*
         * No lock because the caller has promised that this can't
         * change concurrently with device_acquire.
         */
        KASSERTMSG(!dv->dv_detach_done, "%s",
            dv == NULL ? "(null)" : device_xname(dv));
        localcount_acquire(dv->dv_localcount);
}

/*
 * device_release:
 *
 *      Release a reference to a device acquired with device_acquire or
 *      device_lookup_acquire.
 */
void
device_release(device_t dv)
{

        localcount_release(dv->dv_localcount,
            &config_misc_cv, &config_misc_lock);
}

/*
 * device_find_by_xname:
 *
 *      Returns the device of the given name or NULL if it doesn't exist.
 */
device_t
device_find_by_xname(const char *name)
{
        device_t dv;
        deviter_t di;

        for (dv = deviter_first(&di, 0); dv != NULL; dv = deviter_next(&di)) {
                if (strcmp(device_xname(dv), name) == 0)
                        break;
        }
        deviter_release(&di);

        return dv;
}

/*
 * device_find_by_driver_unit:
 *
 *      Returns the device of the given driver name and unit or
 *      NULL if it doesn't exist.
 */
device_t
device_find_by_driver_unit(const char *name, int unit)
{
        struct cfdriver *cd;

        if ((cd = config_cfdriver_lookup(name)) == NULL)
                return NULL;
        return device_lookup(cd, unit);
}

static bool
match_strcmp(const char * const s1, const char * const s2)
{
        return strcmp(s1, s2) == 0;
}

static bool
match_pmatch(const char * const s1, const char * const s2)
{
        return pmatch(s1, s2, NULL) == 2;
}

static bool
strarray_match_internal(const char ** const strings,
    unsigned int const nstrings, const char * const str,
    unsigned int * const indexp,
    bool (*match_fn)(const char *, const char *))
{
        unsigned int i;

        if (strings == NULL || nstrings == 0) {
                return false;
        }

        for (i = 0; i < nstrings; i++) {
                if ((*match_fn)(strings[i], str)) {
                        *indexp = i;
                        return true;
                }
        }

        return false;
}

static int
strarray_match(const char ** const strings, unsigned int const nstrings,
    const char * const str)
{
        unsigned int idx;

        if (strarray_match_internal(strings, nstrings, str, &idx,
                                    match_strcmp)) {
                return (int)(nstrings - idx);
        }
        return 0;
}

static int
strarray_pmatch(const char ** const strings, unsigned int const nstrings,
    const char * const pattern)
{
        unsigned int idx;

        if (strarray_match_internal(strings, nstrings, pattern, &idx,
                                    match_pmatch)) {
                return (int)(nstrings - idx);
        }
        return 0;
}

static int
device_compatible_match_strarray_internal(
    const char **device_compats, int ndevice_compats,
    const struct device_compatible_entry *driver_compats,
    const struct device_compatible_entry **matching_entryp,
    int (*match_fn)(const char **, unsigned int, const char *))
{
        const struct device_compatible_entry *dce = NULL;
        int rv;

        if (ndevice_compats == 0 || device_compats == NULL ||
            driver_compats == NULL)
                return 0;

        for (dce = driver_compats; dce->compat != NULL; dce++) {
                rv = (*match_fn)(device_compats, ndevice_compats, dce->compat);
                if (rv != 0) {
                        if (matching_entryp != NULL) {
                                *matching_entryp = dce;
                        }
                        return rv;
                }
        }
        return 0;
}

/*
 * device_compatible_match:
 *
 *      Match a driver's "compatible" data against a device's
 *      "compatible" strings.  Returns resulted weighted by
 *      which device "compatible" string was matched.
 */
int
device_compatible_match(const char **device_compats, int ndevice_compats,
    const struct device_compatible_entry *driver_compats)
{
        return device_compatible_match_strarray_internal(device_compats,
            ndevice_compats, driver_compats, NULL, strarray_match);
}

/*
 * device_compatible_pmatch:
 *
 *      Like device_compatible_match(), but uses pmatch(9) to compare
 *      the device "compatible" strings against patterns in the
 *      driver's "compatible" data.
 */
int
device_compatible_pmatch(const char **device_compats, int ndevice_compats,
    const struct device_compatible_entry *driver_compats)
{
        return device_compatible_match_strarray_internal(device_compats,
            ndevice_compats, driver_compats, NULL, strarray_pmatch);
}

static int
device_compatible_match_strlist_internal(
    const char * const device_compats, size_t const device_compatsize,
    const struct device_compatible_entry *driver_compats,
    const struct device_compatible_entry **matching_entryp,
    int (*match_fn)(const char *, size_t, const char *))
{
        const struct device_compatible_entry *dce = NULL;
        int rv;

        if (device_compats == NULL || device_compatsize == 0 ||
            driver_compats == NULL)
                return 0;

        for (dce = driver_compats; dce->compat != NULL; dce++) {
                rv = (*match_fn)(device_compats, device_compatsize,
                    dce->compat);
                if (rv != 0) {
                        if (matching_entryp != NULL) {
                                *matching_entryp = dce;
                        }
                        return rv;
                }
        }
        return 0;
}

/*
 * device_compatible_match_strlist:
 *
 *      Like device_compatible_match(), but take the device
 *      "compatible" strings as an OpenFirmware-style string
 *      list.
 */
int
device_compatible_match_strlist(
    const char * const device_compats, size_t const device_compatsize,
    const struct device_compatible_entry *driver_compats)
{
        return device_compatible_match_strlist_internal(device_compats,
            device_compatsize, driver_compats, NULL, strlist_match);
}

/*
 * device_compatible_pmatch_strlist:
 *
 *      Like device_compatible_pmatch(), but take the device
 *      "compatible" strings as an OpenFirmware-style string
 *      list.
 */
int
device_compatible_pmatch_strlist(
    const char * const device_compats, size_t const device_compatsize,
    const struct device_compatible_entry *driver_compats)
{
        return device_compatible_match_strlist_internal(device_compats,
            device_compatsize, driver_compats, NULL, strlist_pmatch);
}

static int
device_compatible_match_id_internal(
    uintptr_t const id, uintptr_t const mask, uintptr_t const sentinel_id,
    const struct device_compatible_entry *driver_compats,
    const struct device_compatible_entry **matching_entryp)
{
        const struct device_compatible_entry *dce = NULL;

        if (mask == 0)
                return 0;

        for (dce = driver_compats; dce->id != sentinel_id; dce++) {
                if ((id & mask) == dce->id) {
                        if (matching_entryp != NULL) {
                                *matching_entryp = dce;
                        }
                        return 1;
                }
        }
        return 0;
}

/*
 * device_compatible_match_id:
 *
 *      Like device_compatible_match(), but takes a single
 *      unsigned integer device ID.
 */
int
device_compatible_match_id(
    uintptr_t const id, uintptr_t const sentinel_id,
    const struct device_compatible_entry *driver_compats)
{
        return device_compatible_match_id_internal(id, (uintptr_t)-1,
            sentinel_id, driver_compats, NULL);
}

/*
 * device_compatible_lookup:
 *
 *      Look up and return the device_compatible_entry, using the
 *      same matching criteria used by device_compatible_match().
 */
const struct device_compatible_entry *
device_compatible_lookup(const char **device_compats, int ndevice_compats,
                         const struct device_compatible_entry *driver_compats)
{
        const struct device_compatible_entry *dce;

        if (device_compatible_match_strarray_internal(device_compats,
            ndevice_compats, driver_compats, &dce, strarray_match)) {
                return dce;
        }
        return NULL;
}

/*
 * device_compatible_plookup:
 *
 *      Look up and return the device_compatible_entry, using the
 *      same matching criteria used by device_compatible_pmatch().
 */
const struct device_compatible_entry *
device_compatible_plookup(const char **device_compats, int ndevice_compats,
                          const struct device_compatible_entry *driver_compats)
{
        const struct device_compatible_entry *dce;

        if (device_compatible_match_strarray_internal(device_compats,
            ndevice_compats, driver_compats, &dce, strarray_pmatch)) {
                return dce;
        }
        return NULL;
}

/*
 * device_compatible_lookup_strlist:
 *
 *      Like device_compatible_lookup(), but take the device
 *      "compatible" strings as an OpenFirmware-style string
 *      list.
 */
const struct device_compatible_entry *
device_compatible_lookup_strlist(
    const char * const device_compats, size_t const device_compatsize,
    const struct device_compatible_entry *driver_compats)
{
        const struct device_compatible_entry *dce;

        if (device_compatible_match_strlist_internal(device_compats,
            device_compatsize, driver_compats, &dce, strlist_match)) {
                return dce;
        }
        return NULL;
}

/*
 * device_compatible_plookup_strlist:
 *
 *      Like device_compatible_plookup(), but take the device
 *      "compatible" strings as an OpenFirmware-style string
 *      list.
 */
const struct device_compatible_entry *
device_compatible_plookup_strlist(
    const char * const device_compats, size_t const device_compatsize,
    const struct device_compatible_entry *driver_compats)
{
        const struct device_compatible_entry *dce;

        if (device_compatible_match_strlist_internal(device_compats,
            device_compatsize, driver_compats, &dce, strlist_pmatch)) {
                return dce;
        }
        return NULL;
}

/*
 * device_compatible_lookup_id:
 *
 *      Like device_compatible_lookup(), but takes a single
 *      unsigned integer device ID.
 */
const struct device_compatible_entry *
device_compatible_lookup_id(
    uintptr_t const id, uintptr_t const sentinel_id,
    const struct device_compatible_entry *driver_compats)
{
        const struct device_compatible_entry *dce;

        if (device_compatible_match_id_internal(id, (uintptr_t)-1,
            sentinel_id, driver_compats, &dce)) {
                return dce;
        }
        return NULL;
}

/*
 * Power management related functions.
 */

bool
device_pmf_is_registered(device_t dev)
{
        return (dev->dv_flags & DVF_POWER_HANDLERS) != 0;
}

bool
device_pmf_driver_suspend(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_DRIVER_SUSPENDED) != 0)
                return true;
        if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0)
                return false;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_DRIVER &&
            dev->dv_driver_suspend != NULL &&
            !(*dev->dv_driver_suspend)(dev, qual))
                return false;

        dev->dv_flags |= DVF_DRIVER_SUSPENDED;
        return true;
}

bool
device_pmf_driver_resume(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_DRIVER_SUSPENDED) == 0)
                return true;
        if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0)
                return false;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_DRIVER &&
            dev->dv_driver_resume != NULL &&
            !(*dev->dv_driver_resume)(dev, qual))
                return false;

        dev->dv_flags &= ~DVF_DRIVER_SUSPENDED;
        return true;
}

bool
device_pmf_driver_shutdown(device_t dev, int how)
{

        if (*dev->dv_driver_shutdown != NULL &&
            !(*dev->dv_driver_shutdown)(dev, how))
                return false;
        return true;
}

void
device_pmf_driver_register(device_t dev,
    bool (*suspend)(device_t, const pmf_qual_t *),
    bool (*resume)(device_t, const pmf_qual_t *),
    bool (*shutdown)(device_t, int))
{

        dev->dv_driver_suspend = suspend;
        dev->dv_driver_resume = resume;
        dev->dv_driver_shutdown = shutdown;
        dev->dv_flags |= DVF_POWER_HANDLERS;
}

void
device_pmf_driver_deregister(device_t dev)
{
        device_lock_t dvl = device_getlock(dev);

        dev->dv_driver_suspend = NULL;
        dev->dv_driver_resume = NULL;

        mutex_enter(&dvl->dvl_mtx);
        dev->dv_flags &= ~DVF_POWER_HANDLERS;
        while (dvl->dvl_nlock > 0 || dvl->dvl_nwait > 0) {
                /* Wake a thread that waits for the lock.  That
                 * thread will fail to acquire the lock, and then
                 * it will wake the next thread that waits for the
                 * lock, or else it will wake us.
                 */
                cv_signal(&dvl->dvl_cv);
                pmflock_debug(dev, __func__, __LINE__);
                cv_wait(&dvl->dvl_cv, &dvl->dvl_mtx);
                pmflock_debug(dev, __func__, __LINE__);
        }
        mutex_exit(&dvl->dvl_mtx);
}

void
device_pmf_driver_child_register(device_t dev)
{
        device_t parent = device_parent(dev);

        if (parent == NULL || parent->dv_driver_child_register == NULL)
                return;
        (*parent->dv_driver_child_register)(dev);
}

void
device_pmf_driver_set_child_register(device_t dev,
    void (*child_register)(device_t))
{
        dev->dv_driver_child_register = child_register;
}

static void
pmflock_debug(device_t dev, const char *func, int line)
{
#ifdef PMFLOCK_DEBUG
        device_lock_t dvl = device_getlock(dev);
        const char *curlwp_name;

        if (curlwp->l_name != NULL)
                curlwp_name = curlwp->l_name;
        else
                curlwp_name = curlwp->l_proc->p_comm;

        aprint_debug_dev(dev,
            "%s.%d, %s dvl_nlock %d dvl_nwait %d dv_flags %x\n", func, line,
            curlwp_name, dvl->dvl_nlock, dvl->dvl_nwait, dev->dv_flags);
#endif  /* PMFLOCK_DEBUG */
}

static bool
device_pmf_lock1(device_t dev)
{
        device_lock_t dvl = device_getlock(dev);

        while (device_pmf_is_registered(dev) &&
            dvl->dvl_nlock > 0 && dvl->dvl_holder != curlwp) {
                dvl->dvl_nwait++;
                pmflock_debug(dev, __func__, __LINE__);
                cv_wait(&dvl->dvl_cv, &dvl->dvl_mtx);
                pmflock_debug(dev, __func__, __LINE__);
                dvl->dvl_nwait--;
        }
        if (!device_pmf_is_registered(dev)) {
                pmflock_debug(dev, __func__, __LINE__);
                /* We could not acquire the lock, but some other thread may
                 * wait for it, also.  Wake that thread.
                 */
                cv_signal(&dvl->dvl_cv);
                return false;
        }
        dvl->dvl_nlock++;
        dvl->dvl_holder = curlwp;
        pmflock_debug(dev, __func__, __LINE__);
        return true;
}

bool
device_pmf_lock(device_t dev)
{
        bool rc;
        device_lock_t dvl = device_getlock(dev);

        mutex_enter(&dvl->dvl_mtx);
        rc = device_pmf_lock1(dev);
        mutex_exit(&dvl->dvl_mtx);

        return rc;
}

void
device_pmf_unlock(device_t dev)
{
        device_lock_t dvl = device_getlock(dev);

        KASSERT(dvl->dvl_nlock > 0);
        mutex_enter(&dvl->dvl_mtx);
        if (--dvl->dvl_nlock == 0)
                dvl->dvl_holder = NULL;
        cv_signal(&dvl->dvl_cv);
        pmflock_debug(dev, __func__, __LINE__);
        mutex_exit(&dvl->dvl_mtx);
}

device_lock_t
device_getlock(device_t dev)
{
        return &dev->dv_lock;
}

void *
device_pmf_bus_private(device_t dev)
{
        return dev->dv_bus_private;
}

bool
device_pmf_bus_suspend(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0)
                return true;
        if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0 ||
            (dev->dv_flags & DVF_DRIVER_SUSPENDED) == 0)
                return false;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_BUS &&
            dev->dv_bus_suspend != NULL &&
            !(*dev->dv_bus_suspend)(dev, qual))
                return false;

        dev->dv_flags |= DVF_BUS_SUSPENDED;
        return true;
}

bool
device_pmf_bus_resume(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_BUS_SUSPENDED) == 0)
                return true;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_BUS &&
            dev->dv_bus_resume != NULL &&
            !(*dev->dv_bus_resume)(dev, qual))
                return false;

        dev->dv_flags &= ~DVF_BUS_SUSPENDED;
        return true;
}

bool
device_pmf_bus_shutdown(device_t dev, int how)
{

        if (*dev->dv_bus_shutdown != NULL &&
            !(*dev->dv_bus_shutdown)(dev, how))
                return false;
        return true;
}

void
device_pmf_bus_register(device_t dev, void *priv,
    bool (*suspend)(device_t, const pmf_qual_t *),
    bool (*resume)(device_t, const pmf_qual_t *),
    bool (*shutdown)(device_t, int), void (*deregister)(device_t))
{
        dev->dv_bus_private = priv;
        dev->dv_bus_resume = resume;
        dev->dv_bus_suspend = suspend;
        dev->dv_bus_shutdown = shutdown;
        dev->dv_bus_deregister = deregister;
}

void
device_pmf_bus_deregister(device_t dev)
{
        if (dev->dv_bus_deregister == NULL)
                return;
        (*dev->dv_bus_deregister)(dev);
        dev->dv_bus_private = NULL;
        dev->dv_bus_suspend = NULL;
        dev->dv_bus_resume = NULL;
        dev->dv_bus_deregister = NULL;
}

void *
device_pmf_class_private(device_t dev)
{
        return dev->dv_class_private;
}

bool
device_pmf_class_suspend(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_CLASS_SUSPENDED) != 0)
                return true;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_CLASS &&
            dev->dv_class_suspend != NULL &&
            !(*dev->dv_class_suspend)(dev, qual))
                return false;

        dev->dv_flags |= DVF_CLASS_SUSPENDED;
        return true;
}

bool
device_pmf_class_resume(device_t dev, const pmf_qual_t *qual)
{
        if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0)
                return true;
        if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0 ||
            (dev->dv_flags & DVF_DRIVER_SUSPENDED) != 0)
                return false;
        if (pmf_qual_depth(qual) <= DEVACT_LEVEL_CLASS &&
            dev->dv_class_resume != NULL &&
            !(*dev->dv_class_resume)(dev, qual))
                return false;

        dev->dv_flags &= ~DVF_CLASS_SUSPENDED;
        return true;
}

void
device_pmf_class_register(device_t dev, void *priv,
    bool (*suspend)(device_t, const pmf_qual_t *),
    bool (*resume)(device_t, const pmf_qual_t *),
    void (*deregister)(device_t))
{
        dev->dv_class_private = priv;
        dev->dv_class_suspend = suspend;
        dev->dv_class_resume = resume;
        dev->dv_class_deregister = deregister;
}

void
device_pmf_class_deregister(device_t dev)
{
        if (dev->dv_class_deregister == NULL)
                return;
        (*dev->dv_class_deregister)(dev);
        dev->dv_class_private = NULL;
        dev->dv_class_suspend = NULL;
        dev->dv_class_resume = NULL;
        dev->dv_class_deregister = NULL;
}

bool
device_active(device_t dev, devactive_t type)
{
        size_t i;

        if (dev->dv_activity_count == 0)
                return false;

        for (i = 0; i < dev->dv_activity_count; ++i) {
                if (dev->dv_activity_handlers[i] == NULL)
                        break;
                (*dev->dv_activity_handlers[i])(dev, type);
        }

        return true;
}

bool
device_active_register(device_t dev, void (*handler)(device_t, devactive_t))
{
        void (**new_handlers)(device_t, devactive_t);
        void (**old_handlers)(device_t, devactive_t);
        size_t i, old_size, new_size;
        int s;

        old_handlers = dev->dv_activity_handlers;
        old_size = dev->dv_activity_count;

        KASSERT(old_size == 0 || old_handlers != NULL);

        for (i = 0; i < old_size; ++i) {
                KASSERT(old_handlers[i] != handler);
                if (old_handlers[i] == NULL) {
                        old_handlers[i] = handler;
                        return true;
                }
        }

        new_size = old_size + 4;
        new_handlers = kmem_alloc(sizeof(void *) * new_size, KM_SLEEP);

        for (i = 0; i < old_size; ++i)
                new_handlers[i] = old_handlers[i];
        new_handlers[old_size] = handler;
        for (i = old_size+1; i < new_size; ++i)
                new_handlers[i] = NULL;

        s = splhigh();
        dev->dv_activity_count = new_size;
        dev->dv_activity_handlers = new_handlers;
        splx(s);

        if (old_size > 0)
                kmem_free(old_handlers, sizeof(void *) * old_size);

        return true;
}

void
device_active_deregister(device_t dev, void (*handler)(device_t, devactive_t))
{
        void (**old_handlers)(device_t, devactive_t);
        size_t i, old_size;
        int s;

        old_handlers = dev->dv_activity_handlers;
        old_size = dev->dv_activity_count;

        for (i = 0; i < old_size; ++i) {
                if (old_handlers[i] == handler)
                        break;
                if (old_handlers[i] == NULL)
                        return; /* XXX panic? */
        }

        if (i == old_size)
                return; /* XXX panic? */

        for (; i < old_size - 1; ++i) {
                if ((old_handlers[i] = old_handlers[i + 1]) != NULL)
                        continue;

                if (i == 0) {
                        s = splhigh();
                        dev->dv_activity_count = 0;
                        dev->dv_activity_handlers = NULL;
                        splx(s);
                        kmem_free(old_handlers, sizeof(void *) * old_size);
                }
                return;
        }
        old_handlers[i] = NULL;
}

/* Return true iff the device_t `dev' exists at generation `gen'. */
static bool
device_exists_at(device_t dv, devgen_t gen)
{
        return (dv->dv_del_gen == 0 || dv->dv_del_gen > gen) &&
            dv->dv_add_gen <= gen;
}

static bool
deviter_visits(const deviter_t *di, device_t dv)
{
        return device_exists_at(dv, di->di_gen);
}

/*
 * Device Iteration
 *
 * deviter_t: a device iterator.  Holds state for a "walk" visiting
 *     each device_t's in the device tree.
 *
 * deviter_init(di, flags): initialize the device iterator `di'
 *     to "walk" the device tree.  deviter_next(di) will return
 *     the first device_t in the device tree, or NULL if there are
 *     no devices.
 *
 *     `flags' is one or more of DEVITER_F_RW, indicating that the
 *     caller intends to modify the device tree by calling
 *     config_detach(9) on devices in the order that the iterator
 *     returns them; DEVITER_F_ROOT_FIRST, asking for the devices
 *     nearest the "root" of the device tree to be returned, first;
 *     DEVITER_F_LEAVES_FIRST, asking for the devices furthest from
 *     the root of the device tree, first; and DEVITER_F_SHUTDOWN,
 *     indicating both that deviter_init() should not respect any
 *     locks on the device tree, and that deviter_next(di) may run
 *     in more than one LWP before the walk has finished.
 *
 *     Only one DEVITER_F_RW iterator may be in the device tree at
 *     once.
 *
 *     DEVITER_F_SHUTDOWN implies DEVITER_F_RW.
 *
 *     Results are undefined if the flags DEVITER_F_ROOT_FIRST and
 *     DEVITER_F_LEAVES_FIRST are used in combination.
 *
 * deviter_first(di, flags): initialize the device iterator `di'
 *     and return the first device_t in the device tree, or NULL
 *     if there are no devices.  The statement
 *
 *         dv = deviter_first(di);
 *
 *     is shorthand for
 *
 *         deviter_init(di);
 *         dv = deviter_next(di);
 *
 * deviter_next(di): return the next device_t in the device tree,
 *     or NULL if there are no more devices.  deviter_next(di)
 *     is undefined if `di' was not initialized with deviter_init() or
 *     deviter_first().
 *
 * deviter_release(di): stops iteration (subsequent calls to
 *     deviter_next() will return NULL), releases any locks and
 *     resources held by the device iterator.
 *
 * Device iteration does not return device_t's in any particular
 * order.  An iterator will never return the same device_t twice.
 * Device iteration is guaranteed to complete---i.e., if deviter_next(di)
 * is called repeatedly on the same `di', it will eventually return
 * NULL.  It is ok to attach/detach devices during device iteration.
 */
void
deviter_init(deviter_t *di, deviter_flags_t flags)
{
        device_t dv;

        memset(di, 0, sizeof(*di));

        if ((flags & DEVITER_F_SHUTDOWN) != 0)
                flags |= DEVITER_F_RW;

        mutex_enter(&alldevs_lock);
        if ((flags & DEVITER_F_RW) != 0)
                alldevs_nwrite++;
        else
                alldevs_nread++;
        di->di_gen = alldevs_gen++;
        di->di_flags = flags;

        switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
        case DEVITER_F_LEAVES_FIRST:
                TAILQ_FOREACH(dv, &alldevs, dv_list) {
                        if (!deviter_visits(di, dv))
                                continue;
                        di->di_curdepth = MAX(di->di_curdepth, dv->dv_depth);
                }
                break;
        case DEVITER_F_ROOT_FIRST:
                TAILQ_FOREACH(dv, &alldevs, dv_list) {
                        if (!deviter_visits(di, dv))
                                continue;
                        di->di_maxdepth = MAX(di->di_maxdepth, dv->dv_depth);
                }
                break;
        default:
                break;
        }

        deviter_reinit(di);
        mutex_exit(&alldevs_lock);
}

static void
deviter_reinit(deviter_t *di)
{

        KASSERT(mutex_owned(&alldevs_lock));
        if ((di->di_flags & DEVITER_F_RW) != 0)
                di->di_prev = TAILQ_LAST(&alldevs, devicelist);
        else
                di->di_prev = TAILQ_FIRST(&alldevs);
}

device_t
deviter_first(deviter_t *di, deviter_flags_t flags)
{

        deviter_init(di, flags);
        return deviter_next(di);
}

static device_t
deviter_next2(deviter_t *di)
{
        device_t dv;

        KASSERT(mutex_owned(&alldevs_lock));

        dv = di->di_prev;

        if (dv == NULL)
                return NULL;

        if ((di->di_flags & DEVITER_F_RW) != 0)
                di->di_prev = TAILQ_PREV(dv, devicelist, dv_list);
        else
                di->di_prev = TAILQ_NEXT(dv, dv_list);

        return dv;
}

static device_t
deviter_next1(deviter_t *di)
{
        device_t dv;

        KASSERT(mutex_owned(&alldevs_lock));

        do {
                dv = deviter_next2(di);
        } while (dv != NULL && !deviter_visits(di, dv));

        return dv;
}

device_t
deviter_next(deviter_t *di)
{
        device_t dv = NULL;

        mutex_enter(&alldevs_lock);
        switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
        case 0:
                dv = deviter_next1(di);
                break;
        case DEVITER_F_LEAVES_FIRST:
                while (di->di_curdepth >= 0) {
                        if ((dv = deviter_next1(di)) == NULL) {
                                di->di_curdepth--;
                                deviter_reinit(di);
                        } else if (dv->dv_depth == di->di_curdepth)
                                break;
                }
                break;
        case DEVITER_F_ROOT_FIRST:
                while (di->di_curdepth <= di->di_maxdepth) {
                        if ((dv = deviter_next1(di)) == NULL) {
                                di->di_curdepth++;
                                deviter_reinit(di);
                        } else if (dv->dv_depth == di->di_curdepth)
                                break;
                }
                break;
        default:
                break;
        }
        mutex_exit(&alldevs_lock);

        return dv;
}

void
deviter_release(deviter_t *di)
{
        bool rw = (di->di_flags & DEVITER_F_RW) != 0;

        mutex_enter(&alldevs_lock);
        if (rw)
                --alldevs_nwrite;
        else
                --alldevs_nread;
        /* XXX wake a garbage-collection thread */
        mutex_exit(&alldevs_lock);
}

const char *
cfdata_ifattr(const struct cfdata *cf)
{
        return cf->cf_pspec->cfp_iattr;
}

bool
ifattr_match(const char *snull, const char *t)
{
        return (snull == NULL) || strcmp(snull, t) == 0;
}

void
null_childdetached(device_t self, device_t child)
{
        /* do nothing */
}

static void
sysctl_detach_setup(struct sysctllog **clog)
{

        sysctl_createv(clog, 0, NULL, NULL,
                CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                CTLTYPE_BOOL, "detachall",
                SYSCTL_DESCR("Detach all devices at shutdown"),
                NULL, 0, &detachall, 0,
                CTL_KERN, CTL_CREATE, CTL_EOL);
}