subr_rman.c

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/*-
 * Copyright 1998 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. 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.
 */

/*
 * The kernel resource manager.  This code is responsible for keeping track
 * of hardware resources which are apportioned out to various drivers.
 * It does not actually assign those resources, and it is not expected
 * that end-device drivers will call into this code directly.  Rather,
 * the code which implements the buses that those devices are attached to,
 * and the code which manages CPU resources, will call this code, and the
 * end-device drivers will make upcalls to that code to actually perform
 * the allocation.
 *
 * There are two sorts of resources managed by this code.  The first is
 * the more familiar array (RMAN_ARRAY) type; resources in this class
 * consist of a sequence of individually-allocatable objects which have
 * been numbered in some well-defined order.  Most of the resources
 * are of this type, as it is the most familiar.  The second type is
 * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
 * resources in which each instance is indistinguishable from every
 * other instance).  The principal anticipated application of gauges
 * is in the context of power consumption, where a bus may have a specific
 * power budget which all attached devices share.  RMAN_GAUGE is not
 * implemented yet.
 *
 * For array resources, we make one simplifying assumption: two clients
 * sharing the same resource must use the same range of indices.  That
 * is to say, sharing of overlapping-but-not-identical regions is not
 * permitted.
 */

#include "opt_ddb.h"

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/bus.h>            /* XXX debugging */
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/sysctl.h>

#ifdef DDB
#include <ddb/ddb.h>
#endif

/*
 * We use a linked list rather than a bitmap because we need to be able to
 * represent potentially huge objects (like all of a processor's physical
 * address space).  That is also why the indices are defined to have type
 * `unsigned long' -- that being the largest integral type in ISO C (1990).
 * The 1999 version of C allows `long long'; we may need to switch to that
 * at some point in the future, particularly if we want to support 36-bit
 * addresses on IA32 hardware.
 */
struct resource_i {
        struct resource         r_r;
        TAILQ_ENTRY(resource_i) r_link;
        LIST_ENTRY(resource_i)  r_sharelink;
        LIST_HEAD(, resource_i) *r_sharehead;
        u_long  r_start;        /* index of the first entry in this resource */
        u_long  r_end;          /* index of the last entry (inclusive) */
        u_int   r_flags;
        void    *r_virtual;     /* virtual address of this resource */
        struct device *r_dev;   /* device which has allocated this resource */
        struct rman *r_rm;      /* resource manager from whence this came */
        int     r_rid;          /* optional rid for this resource. */
};

static int rman_debug = 0;
TUNABLE_INT("debug.rman_debug", &rman_debug);
SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
    &rman_debug, 0, "rman debug");

#define DPRINTF(params) if (rman_debug) printf params

static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");

struct rman_head rman_head;
static struct mtx rman_mtx; /* mutex to protect rman_head */
static int int_rman_release_resource(struct rman *rm, struct resource_i *r);

static __inline struct resource_i *
int_alloc_resource(int malloc_flag)
{
        struct resource_i *r;

        r = malloc(sizeof *r, M_RMAN, malloc_flag | M_ZERO);
        if (r != NULL) {
                r->r_r.__r_i = r;
        }
        return (r);
}

int
rman_init(struct rman *rm)
{
        static int once = 0;

        if (once == 0) {
                once = 1;
                TAILQ_INIT(&rman_head);
                mtx_init(&rman_mtx, "rman head", NULL, MTX_DEF);
        }

        if (rm->rm_start == 0 && rm->rm_end == 0)
                rm->rm_end = ~0ul;
        if (rm->rm_type == RMAN_UNINIT)
                panic("rman_init");
        if (rm->rm_type == RMAN_GAUGE)
                panic("implement RMAN_GAUGE");

        TAILQ_INIT(&rm->rm_list);
        rm->rm_mtx = malloc(sizeof *rm->rm_mtx, M_RMAN, M_NOWAIT | M_ZERO);
        if (rm->rm_mtx == NULL)
                return ENOMEM;
        mtx_init(rm->rm_mtx, "rman", NULL, MTX_DEF);

        mtx_lock(&rman_mtx);
        TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
        mtx_unlock(&rman_mtx);
        return 0;
}

int
rman_manage_region(struct rman *rm, u_long start, u_long end)
{
        struct resource_i *r, *s, *t;

        DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
            rm->rm_descr, start, end));
        if (start < rm->rm_start || end > rm->rm_end)
                return EINVAL;
        r = int_alloc_resource(M_NOWAIT);
        if (r == NULL)
                return ENOMEM;
        r->r_start = start;
        r->r_end = end;
        r->r_rm = rm;

        mtx_lock(rm->rm_mtx);

        /* Skip entries before us. */
        TAILQ_FOREACH(s, &rm->rm_list, r_link) {
                if (s->r_end == ULONG_MAX)
                        break;
                if (s->r_end + 1 >= r->r_start)
                        break;
        }

        /* If we ran off the end of the list, insert at the tail. */
        if (s == NULL) {
                TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
        } else {
                /* Check for any overlap with the current region. */
                if (r->r_start <= s->r_end && r->r_end >= s->r_start)
                        return EBUSY;

                /* Check for any overlap with the next region. */
                t = TAILQ_NEXT(s, r_link);
                if (t && r->r_start <= t->r_end && r->r_end >= t->r_start)
                        return EBUSY;

                /*
                 * See if this region can be merged with the next region.  If
                 * not, clear the pointer.
                 */
                if (t && (r->r_end + 1 != t->r_start || t->r_flags != 0))
                        t = NULL;

                /* See if we can merge with the current region. */
                if (s->r_end + 1 == r->r_start && s->r_flags == 0) {
                        /* Can we merge all 3 regions? */
                        if (t != NULL) {
                                s->r_end = t->r_end;
                                TAILQ_REMOVE(&rm->rm_list, t, r_link);
                                free(r, M_RMAN);
                                free(t, M_RMAN);
                        } else {
                                s->r_end = r->r_end;
                                free(r, M_RMAN);
                        }
                } else if (t != NULL) {
                        /* Can we merge with just the next region? */
                        t->r_start = r->r_start;
                        free(r, M_RMAN);
                } else if (s->r_end < r->r_start) {
                        TAILQ_INSERT_AFTER(&rm->rm_list, s, r, r_link);
                } else {
                        TAILQ_INSERT_BEFORE(s, r, r_link);
                }
        }

        mtx_unlock(rm->rm_mtx);
        return 0;
}

int
rman_init_from_resource(struct rman *rm, struct resource *r)
{
        int rv;

        if ((rv = rman_init(rm)) != 0)
                return (rv);
        return (rman_manage_region(rm, r->__r_i->r_start, r->__r_i->r_end));
}

int
rman_fini(struct rman *rm)
{
        struct resource_i *r;

        mtx_lock(rm->rm_mtx);
        TAILQ_FOREACH(r, &rm->rm_list, r_link) {
                if (r->r_flags & RF_ALLOCATED) {
                        mtx_unlock(rm->rm_mtx);
                        return EBUSY;
                }
        }

        /*
         * There really should only be one of these if we are in this
         * state and the code is working properly, but it can't hurt.
         */
        while (!TAILQ_EMPTY(&rm->rm_list)) {
                r = TAILQ_FIRST(&rm->rm_list);
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
                free(r, M_RMAN);
        }
        mtx_unlock(rm->rm_mtx);
        mtx_lock(&rman_mtx);
        TAILQ_REMOVE(&rman_head, rm, rm_link);
        mtx_unlock(&rman_mtx);
        mtx_destroy(rm->rm_mtx);
        free(rm->rm_mtx, M_RMAN);

        return 0;
}

int
rman_first_free_region(struct rman *rm, u_long *start, u_long *end)
{
        struct resource_i *r;

        mtx_lock(rm->rm_mtx);
        TAILQ_FOREACH(r, &rm->rm_list, r_link) {
                if (!(r->r_flags & RF_ALLOCATED)) {
                        *start = r->r_start;
                        *end = r->r_end;
                        mtx_unlock(rm->rm_mtx);
                        return (0);
                }
        }
        mtx_unlock(rm->rm_mtx);
        return (ENOENT);
}

int
rman_last_free_region(struct rman *rm, u_long *start, u_long *end)
{
        struct resource_i *r;

        mtx_lock(rm->rm_mtx);
        TAILQ_FOREACH_REVERSE(r, &rm->rm_list, resource_head, r_link) {
                if (!(r->r_flags & RF_ALLOCATED)) {
                        *start = r->r_start;
                        *end = r->r_end;
                        mtx_unlock(rm->rm_mtx);
                        return (0);
                }
        }
        mtx_unlock(rm->rm_mtx);
        return (ENOENT);
}

/* Shrink or extend one or both ends of an allocated resource. */
int
rman_adjust_resource(struct resource *rr, u_long start, u_long end)
{
        struct resource_i *r, *s, *t, *new;
        struct rman *rm;

        /* Not supported for shared resources. */
        r = rr->__r_i;
        if (r->r_flags & RF_SHAREABLE)
                return (EINVAL);

        /*
         * This does not support wholesale moving of a resource.  At
         * least part of the desired new range must overlap with the
         * existing resource.
         */
        if (end < r->r_start || r->r_end < start)
                return (EINVAL);

        /*
         * Find the two resource regions immediately adjacent to the
         * allocated resource.
         */
        rm = r->r_rm;
        mtx_lock(rm->rm_mtx);
#ifdef INVARIANTS
        TAILQ_FOREACH(s, &rm->rm_list, r_link) {
                if (s == r)
                        break;
        }
        if (s == NULL)
                panic("resource not in list");
#endif
        s = TAILQ_PREV(r, resource_head, r_link);
        t = TAILQ_NEXT(r, r_link);
        KASSERT(s == NULL || s->r_end + 1 == r->r_start,
            ("prev resource mismatch"));
        KASSERT(t == NULL || r->r_end + 1 == t->r_start,
            ("next resource mismatch"));

        /*
         * See if the changes are permitted.  Shrinking is always allowed,
         * but growing requires sufficient room in the adjacent region.
         */
        if (start < r->r_start && (s == NULL || (s->r_flags & RF_ALLOCATED) ||
            s->r_start > start)) {
                mtx_unlock(rm->rm_mtx);
                return (EBUSY);
        }
        if (end > r->r_end && (t == NULL || (t->r_flags & RF_ALLOCATED) ||
            t->r_end < end)) {
                mtx_unlock(rm->rm_mtx);
                return (EBUSY);
        }

        /*
         * While holding the lock, grow either end of the resource as
         * needed and shrink either end if the shrinking does not require
         * allocating a new resource.  We can safely drop the lock and then
         * insert a new range to handle the shrinking case afterwards.
         */
        if (start < r->r_start ||
            (start > r->r_start && s != NULL && !(s->r_flags & RF_ALLOCATED))) {
                KASSERT(s->r_flags == 0, ("prev is busy"));
                r->r_start = start;
                if (s->r_start == start) {
                        TAILQ_REMOVE(&rm->rm_list, s, r_link);
                        free(s, M_RMAN);
                } else
                        s->r_end = start - 1;
        }
        if (end > r->r_end ||
            (end < r->r_end && t != NULL && !(t->r_flags & RF_ALLOCATED))) {
                KASSERT(t->r_flags == 0, ("next is busy"));
                r->r_end = end;
                if (t->r_end == end) {
                        TAILQ_REMOVE(&rm->rm_list, t, r_link);
                        free(t, M_RMAN);
                } else
                        t->r_start = end + 1;
        }
        mtx_unlock(rm->rm_mtx);

        /*
         * Handle the shrinking cases that require allocating a new
         * resource to hold the newly-free region.  We have to recheck
         * if we still need this new region after acquiring the lock.
         */
        if (start > r->r_start) {
                new = int_alloc_resource(M_WAITOK);
                new->r_start = r->r_start;
                new->r_end = start - 1;
                new->r_rm = rm;
                mtx_lock(rm->rm_mtx);
                r->r_start = start;
                s = TAILQ_PREV(r, resource_head, r_link);
                if (s != NULL && !(s->r_flags & RF_ALLOCATED)) {
                        s->r_end = start - 1;
                        free(new, M_RMAN);
                } else
                        TAILQ_INSERT_BEFORE(r, new, r_link);
                mtx_unlock(rm->rm_mtx);
        }
        if (end < r->r_end) {
                new = int_alloc_resource(M_WAITOK);
                new->r_start = end + 1;
                new->r_end = r->r_end;
                new->r_rm = rm;
                mtx_lock(rm->rm_mtx);
                r->r_end = end;
                t = TAILQ_NEXT(r, r_link);
                if (t != NULL && !(t->r_flags & RF_ALLOCATED)) {
                        t->r_start = end + 1;
                        free(new, M_RMAN);
                } else
                        TAILQ_INSERT_AFTER(&rm->rm_list, r, new, r_link);
                mtx_unlock(rm->rm_mtx);
        }
        return (0);
}

#define SHARE_TYPE(f)   (f & (RF_SHAREABLE | RF_PREFETCHABLE))

struct resource *
rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
                            u_long count, u_long bound, u_int flags,
                            struct device *dev)
{
        u_int new_rflags;
        struct resource_i *r, *s, *rv;
        u_long rstart, rend, amask, bmask;

        rv = NULL;

        DPRINTF(("rman_reserve_resource_bound: <%s> request: [%#lx, %#lx], "
               "length %#lx, flags %u, device %s\n", rm->rm_descr, start, end,
               count, flags,
               dev == NULL ? "<null>" : device_get_nameunit(dev)));
        KASSERT((flags & RF_FIRSTSHARE) == 0,
            ("invalid flags %#x", flags));
        new_rflags = (flags & ~RF_FIRSTSHARE) | RF_ALLOCATED;

        mtx_lock(rm->rm_mtx);

        for (r = TAILQ_FIRST(&rm->rm_list);
             r && r->r_end < start + count - 1;
             r = TAILQ_NEXT(r, r_link))
                ;

        if (r == NULL) {
                DPRINTF(("could not find a region\n"));
                goto out;
        }

        amask = (1ul << RF_ALIGNMENT(flags)) - 1;
        KASSERT(start <= ULONG_MAX - amask,
            ("start (%#lx) + amask (%#lx) would wrap around", start, amask));

        /* If bound is 0, bmask will also be 0 */
        bmask = ~(bound - 1);
        /*
         * First try to find an acceptable totally-unshared region.
         */
        for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
                DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
                /*
                 * The resource list is sorted, so there is no point in
                 * searching further once r_start is too large.
                 */
                if (s->r_start > end - (count - 1)) {
                        DPRINTF(("s->r_start (%#lx) + count - 1> end (%#lx)\n",
                            s->r_start, end));
                        break;
                }
                if (s->r_start > ULONG_MAX - amask) {
                        DPRINTF(("s->r_start (%#lx) + amask (%#lx) too large\n",
                            s->r_start, amask));
                        break;
                }
                if (s->r_flags & RF_ALLOCATED) {
                        DPRINTF(("region is allocated\n"));
                        continue;
                }
                rstart = ulmax(s->r_start, start);
                /*
                 * Try to find a region by adjusting to boundary and alignment
                 * until both conditions are satisfied. This is not an optimal
                 * algorithm, but in most cases it isn't really bad, either.
                 */
                do {
                        rstart = (rstart + amask) & ~amask;
                        if (((rstart ^ (rstart + count - 1)) & bmask) != 0)
                                rstart += bound - (rstart & ~bmask);
                } while ((rstart & amask) != 0 && rstart < end &&
                    rstart < s->r_end);
                rend = ulmin(s->r_end, ulmax(rstart + count - 1, end));
                if (rstart > rend) {
                        DPRINTF(("adjusted start exceeds end\n"));
                        continue;
                }
                DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
                       rstart, rend, (rend - rstart + 1), count));

                if ((rend - rstart + 1) >= count) {
                        DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
                               rstart, rend, (rend - rstart + 1)));
                        if ((s->r_end - s->r_start + 1) == count) {
                                DPRINTF(("candidate region is entire chunk\n"));
                                rv = s;
                                rv->r_flags = new_rflags;
                                rv->r_dev = dev;
                                goto out;
                        }

                        /*
                         * If s->r_start < rstart and
                         *    s->r_end > rstart + count - 1, then
                         * we need to split the region into three pieces
                         * (the middle one will get returned to the user).
                         * Otherwise, we are allocating at either the
                         * beginning or the end of s, so we only need to
                         * split it in two.  The first case requires
                         * two new allocations; the second requires but one.
                         */
                        rv = int_alloc_resource(M_NOWAIT);
                        if (rv == NULL)
                                goto out;
                        rv->r_start = rstart;
                        rv->r_end = rstart + count - 1;
                        rv->r_flags = new_rflags;
                        rv->r_dev = dev;
                        rv->r_rm = rm;

                        if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
                                DPRINTF(("splitting region in three parts: "
                                       "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
                                       s->r_start, rv->r_start - 1,
                                       rv->r_start, rv->r_end,
                                       rv->r_end + 1, s->r_end));
                                /*
                                 * We are allocating in the middle.
                                 */
                                r = int_alloc_resource(M_NOWAIT);
                                if (r == NULL) {
                                        free(rv, M_RMAN);
                                        rv = NULL;
                                        goto out;
                                }
                                r->r_start = rv->r_end + 1;
                                r->r_end = s->r_end;
                                r->r_flags = s->r_flags;
                                r->r_rm = rm;
                                s->r_end = rv->r_start - 1;
                                TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
                                                     r_link);
                                TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
                                                     r_link);
                        } else if (s->r_start == rv->r_start) {
                                DPRINTF(("allocating from the beginning\n"));
                                /*
                                 * We are allocating at the beginning.
                                 */
                                s->r_start = rv->r_end + 1;
                                TAILQ_INSERT_BEFORE(s, rv, r_link);
                        } else {
                                DPRINTF(("allocating at the end\n"));
                                /*
                                 * We are allocating at the end.
                                 */
                                s->r_end = rv->r_start - 1;
                                TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
                                                     r_link);
                        }
                        goto out;
                }
        }

        /*
         * Now find an acceptable shared region, if the client's requirements
         * allow sharing.  By our implementation restriction, a candidate
         * region must match exactly by both size and sharing type in order
         * to be considered compatible with the client's request.  (The
         * former restriction could probably be lifted without too much
         * additional work, but this does not seem warranted.)
         */
        DPRINTF(("no unshared regions found\n"));
        if ((flags & RF_SHAREABLE) == 0)
                goto out;

        for (s = r; s && s->r_end <= end; s = TAILQ_NEXT(s, r_link)) {
                if (SHARE_TYPE(s->r_flags) == SHARE_TYPE(flags) &&
                    s->r_start >= start &&
                    (s->r_end - s->r_start + 1) == count &&
                    (s->r_start & amask) == 0 &&
                    ((s->r_start ^ s->r_end) & bmask) == 0) {
                        rv = int_alloc_resource(M_NOWAIT);
                        if (rv == NULL)
                                goto out;
                        rv->r_start = s->r_start;
                        rv->r_end = s->r_end;
                        rv->r_flags = new_rflags;
                        rv->r_dev = dev;
                        rv->r_rm = rm;
                        if (s->r_sharehead == NULL) {
                                s->r_sharehead = malloc(sizeof *s->r_sharehead,
                                                M_RMAN, M_NOWAIT | M_ZERO);
                                if (s->r_sharehead == NULL) {
                                        free(rv, M_RMAN);
                                        rv = NULL;
                                        goto out;
                                }
                                LIST_INIT(s->r_sharehead);
                                LIST_INSERT_HEAD(s->r_sharehead, s,
                                                 r_sharelink);
                                s->r_flags |= RF_FIRSTSHARE;
                        }
                        rv->r_sharehead = s->r_sharehead;
                        LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
                        goto out;
                }
        }
        /*
         * We couldn't find anything.
         */

out:
        mtx_unlock(rm->rm_mtx);
        return (rv == NULL ? NULL : &rv->r_r);
}

struct resource *
rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
                      u_int flags, struct device *dev)
{

        return (rman_reserve_resource_bound(rm, start, end, count, 0, flags,
            dev));
}

int
rman_activate_resource(struct resource *re)
{
        struct resource_i *r;
        struct rman *rm;

        r = re->__r_i;
        rm = r->r_rm;
        mtx_lock(rm->rm_mtx);
        r->r_flags |= RF_ACTIVE;
        mtx_unlock(rm->rm_mtx);
        return 0;
}

int
rman_deactivate_resource(struct resource *r)
{
        struct rman *rm;

        rm = r->__r_i->r_rm;
        mtx_lock(rm->rm_mtx);
        r->__r_i->r_flags &= ~RF_ACTIVE;
        mtx_unlock(rm->rm_mtx);
        return 0;
}

static int
int_rman_release_resource(struct rman *rm, struct resource_i *r)
{
        struct resource_i *s, *t;

        if (r->r_flags & RF_ACTIVE)
                r->r_flags &= ~RF_ACTIVE;

        /*
         * Check for a sharing list first.  If there is one, then we don't
         * have to think as hard.
         */
        if (r->r_sharehead) {
                /*
                 * If a sharing list exists, then we know there are at
                 * least two sharers.
                 *
                 * If we are in the main circleq, appoint someone else.
                 */
                LIST_REMOVE(r, r_sharelink);
                s = LIST_FIRST(r->r_sharehead);
                if (r->r_flags & RF_FIRSTSHARE) {
                        s->r_flags |= RF_FIRSTSHARE;
                        TAILQ_INSERT_BEFORE(r, s, r_link);
                        TAILQ_REMOVE(&rm->rm_list, r, r_link);
                }

                /*
                 * Make sure that the sharing list goes away completely
                 * if the resource is no longer being shared at all.
                 */
                if (LIST_NEXT(s, r_sharelink) == NULL) {
                        free(s->r_sharehead, M_RMAN);
                        s->r_sharehead = NULL;
                        s->r_flags &= ~RF_FIRSTSHARE;
                }
                goto out;
        }

        /*
         * Look at the adjacent resources in the list and see if our
         * segment can be merged with any of them.  If either of the
         * resources is allocated or is not exactly adjacent then they
         * cannot be merged with our segment.
         */
        s = TAILQ_PREV(r, resource_head, r_link);
        if (s != NULL && ((s->r_flags & RF_ALLOCATED) != 0 ||
            s->r_end + 1 != r->r_start))
                s = NULL;
        t = TAILQ_NEXT(r, r_link);
        if (t != NULL && ((t->r_flags & RF_ALLOCATED) != 0 ||
            r->r_end + 1 != t->r_start))
                t = NULL;

        if (s != NULL && t != NULL) {
                /*
                 * Merge all three segments.
                 */
                s->r_end = t->r_end;
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
                TAILQ_REMOVE(&rm->rm_list, t, r_link);
                free(t, M_RMAN);
        } else if (s != NULL) {
                /*
                 * Merge previous segment with ours.
                 */
                s->r_end = r->r_end;
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
        } else if (t != NULL) {
                /*
                 * Merge next segment with ours.
                 */
                t->r_start = r->r_start;
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
        } else {
                /*
                 * At this point, we know there is nothing we
                 * can potentially merge with, because on each
                 * side, there is either nothing there or what is
                 * there is still allocated.  In that case, we don't
                 * want to remove r from the list; we simply want to
                 * change it to an unallocated region and return
                 * without freeing anything.
                 */
                r->r_flags &= ~RF_ALLOCATED;
                r->r_dev = NULL;
                return 0;
        }

out:
        free(r, M_RMAN);
        return 0;
}

int
rman_release_resource(struct resource *re)
{
        int rv;
        struct resource_i *r;
        struct rman *rm;

        r = re->__r_i;
        rm = r->r_rm;
        mtx_lock(rm->rm_mtx);
        rv = int_rman_release_resource(rm, r);
        mtx_unlock(rm->rm_mtx);
        return (rv);
}

uint32_t
rman_make_alignment_flags(uint32_t size)
{
        int i;

        /*
         * Find the hightest bit set, and add one if more than one bit
         * set.  We're effectively computing the ceil(log2(size)) here.
         */
        for (i = 31; i > 0; i--)
                if ((1 << i) & size)
                        break;
        if (~(1 << i) & size)
                i++;

        return(RF_ALIGNMENT_LOG2(i));
}

void
rman_set_start(struct resource *r, u_long start)
{

        r->__r_i->r_start = start;
}

u_long
rman_get_start(struct resource *r)
{

        return (r->__r_i->r_start);
}

void
rman_set_end(struct resource *r, u_long end)
{

        r->__r_i->r_end = end;
}

u_long
rman_get_end(struct resource *r)
{

        return (r->__r_i->r_end);
}

u_long
rman_get_size(struct resource *r)
{

        return (r->__r_i->r_end - r->__r_i->r_start + 1);
}

u_int
rman_get_flags(struct resource *r)
{

        return (r->__r_i->r_flags);
}

void
rman_set_virtual(struct resource *r, void *v)
{

        r->__r_i->r_virtual = v;
}

void *
rman_get_virtual(struct resource *r)
{

        return (r->__r_i->r_virtual);
}

void
rman_set_bustag(struct resource *r, bus_space_tag_t t)
{

        r->r_bustag = t;
}

bus_space_tag_t
rman_get_bustag(struct resource *r)
{

        return (r->r_bustag);
}

void
rman_set_bushandle(struct resource *r, bus_space_handle_t h)
{

        r->r_bushandle = h;
}

bus_space_handle_t
rman_get_bushandle(struct resource *r)
{

        return (r->r_bushandle);
}

void
rman_set_rid(struct resource *r, int rid)
{

        r->__r_i->r_rid = rid;
}

int
rman_get_rid(struct resource *r)
{

        return (r->__r_i->r_rid);
}

void
rman_set_device(struct resource *r, struct device *dev)
{

        r->__r_i->r_dev = dev;
}

struct device *
rman_get_device(struct resource *r)
{

        return (r->__r_i->r_dev);
}

int
rman_is_region_manager(struct resource *r, struct rman *rm)
{

        return (r->__r_i->r_rm == rm);
}

/*
 * Sysctl interface for scanning the resource lists.
 *
 * We take two input parameters; the index into the list of resource
 * managers, and the resource offset into the list.
 */
static int
sysctl_rman(SYSCTL_HANDLER_ARGS)
{
        int                     *name = (int *)arg1;
        u_int                   namelen = arg2;
        int                     rman_idx, res_idx;
        struct rman             *rm;
        struct resource_i       *res;
        struct resource_i       *sres;
        struct u_rman           urm;
        struct u_resource       ures;
        int                     error;

        if (namelen != 3)
                return (EINVAL);

        if (bus_data_generation_check(name[0]))
                return (EINVAL);
        rman_idx = name[1];
        res_idx = name[2];

        /*
         * Find the indexed resource manager
         */
        mtx_lock(&rman_mtx);
        TAILQ_FOREACH(rm, &rman_head, rm_link) {
                if (rman_idx-- == 0)
                        break;
        }
        mtx_unlock(&rman_mtx);
        if (rm == NULL)
                return (ENOENT);

        /*
         * If the resource index is -1, we want details on the
         * resource manager.
         */
        if (res_idx == -1) {
                bzero(&urm, sizeof(urm));
                urm.rm_handle = (uintptr_t)rm;
                if (rm->rm_descr != NULL)
                        strlcpy(urm.rm_descr, rm->rm_descr, RM_TEXTLEN);
                urm.rm_start = rm->rm_start;
                urm.rm_size = rm->rm_end - rm->rm_start + 1;
                urm.rm_type = rm->rm_type;

                error = SYSCTL_OUT(req, &urm, sizeof(urm));
                return (error);
        }

        /*
         * Find the indexed resource and return it.
         */
        mtx_lock(rm->rm_mtx);
        TAILQ_FOREACH(res, &rm->rm_list, r_link) {
                if (res->r_sharehead != NULL) {
                        LIST_FOREACH(sres, res->r_sharehead, r_sharelink)
                                if (res_idx-- == 0) {
                                        res = sres;
                                        goto found;
                                }
                }
                else if (res_idx-- == 0)
                                goto found;
        }
        mtx_unlock(rm->rm_mtx);
        return (ENOENT);

found:
        bzero(&ures, sizeof(ures));
        ures.r_handle = (uintptr_t)res;
        ures.r_parent = (uintptr_t)res->r_rm;
        ures.r_device = (uintptr_t)res->r_dev;
        if (res->r_dev != NULL) {
                if (device_get_name(res->r_dev) != NULL) {
                        snprintf(ures.r_devname, RM_TEXTLEN,
                            "%s%d",
                            device_get_name(res->r_dev),
                            device_get_unit(res->r_dev));
                } else {
                        strlcpy(ures.r_devname, "nomatch",
                            RM_TEXTLEN);
                }
        } else {
                ures.r_devname[0] = '\0';
        }
        ures.r_start = res->r_start;
        ures.r_size = res->r_end - res->r_start + 1;
        ures.r_flags = res->r_flags;

        mtx_unlock(rm->rm_mtx);
        error = SYSCTL_OUT(req, &ures, sizeof(ures));
        return (error);
}

static SYSCTL_NODE(_hw_bus, OID_AUTO, rman, CTLFLAG_RD, sysctl_rman,
    "kernel resource manager");

#ifdef DDB
static void
dump_rman_header(struct rman *rm)
{

        if (db_pager_quit)
                return;
        db_printf("rman %p: %s (0x%lx-0x%lx full range)\n",
            rm, rm->rm_descr, rm->rm_start, rm->rm_end);
}

static void
dump_rman(struct rman *rm)
{
        struct resource_i *r;
        const char *devname;

        if (db_pager_quit)
                return;
        TAILQ_FOREACH(r, &rm->rm_list, r_link) {
                if (r->r_dev != NULL) {
                        devname = device_get_nameunit(r->r_dev);
                        if (devname == NULL)
                                devname = "nomatch";
                } else
                        devname = NULL;
                db_printf("    0x%lx-0x%lx (RID=%d) ",
                    r->r_start, r->r_end, r->r_rid);
                if (devname != NULL)
                        db_printf("(%s)\n", devname);
                else
                        db_printf("----\n");
                if (db_pager_quit)
                        return;
        }
}

DB_SHOW_COMMAND(rman, db_show_rman)
{

        if (have_addr) {
                dump_rman_header((struct rman *)addr);
                dump_rman((struct rman *)addr);
        }
}

DB_SHOW_COMMAND(rmans, db_show_rmans)
{
        struct rman *rm;

        TAILQ_FOREACH(rm, &rman_head, rm_link) {
                dump_rman_header(rm);
        }
}

DB_SHOW_ALL_COMMAND(rman, db_show_all_rman)
{
        struct rman *rm;

        TAILQ_FOREACH(rm, &rman_head, rm_link) {
                dump_rman_header(rm);
                dump_rman(rm);
        }
}
DB_SHOW_ALIAS(allrman, db_show_all_rman);
#endif