/*
 * 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.
 *
 * $FreeBSD: src/sys/kern/subr_rman.c,v 1.10.2.1 2001/06/05 08:06:08 imp Exp $
 */

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

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) kprintf params

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

TAILQ_HEAD(rman_head, rman);
static struct rman_head rman_head;
static struct lwkt_token rman_tok;      /* mutex to protect rman_head */
static int int_rman_activate_resource(struct rman *rm, struct resource *r,
                                       struct resource **whohas);
static int int_rman_deactivate_resource(struct resource *r);
static int int_rman_release_resource(struct rman *rm, struct resource *r);

int
rman_init(struct rman *rm, int cpuid)
{
        static int once;

        if (once == 0) {
                once = 1;
                TAILQ_INIT(&rman_head);
                lwkt_token_init(&rman_tok, "rman");
        }

        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_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
        if (rm->rm_slock == NULL)
                return ENOMEM;
        lwkt_token_init(rm->rm_slock, "rmanslock");

        rm->rm_cpuid = cpuid;
        rm->rm_hold = 0;

        lwkt_gettoken(&rman_tok);
        TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
        lwkt_reltoken(&rman_tok);

        return 0;
}

/*
 * NB: this interface is not robust against programming errors which
 * add multiple copies of the same region.
 */
int
rman_manage_region(struct rman *rm, u_long start, u_long end)
{
        struct resource *r, *s;

        DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
            rm->rm_descr, start, end));
        r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO);
        if (r == NULL)
                return ENOMEM;
        r->r_sharehead = 0;
        r->r_start = start;
        r->r_end = end;
        r->r_flags = 0;
        r->r_dev = 0;
        r->r_rm = rm;

        lwkt_gettoken(rm->rm_slock);
        for (s = TAILQ_FIRST(&rm->rm_list);
             s && s->r_end < r->r_start;
             s = TAILQ_NEXT(s, r_link))
                ;

        if (s == NULL)
                TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
        else
                TAILQ_INSERT_BEFORE(s, r, r_link);

        lwkt_reltoken(rm->rm_slock);
        return 0;
}

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

        /*
         * All resources must already have been deallocated.
         */
        lwkt_gettoken(rm->rm_slock);
        TAILQ_FOREACH(r, &rm->rm_list, r_link) {
                if (r->r_flags & RF_ALLOCATED) {
                        lwkt_reltoken(rm->rm_slock);
                        return EBUSY;
                }
        }

        /*
         * Protected list removal.  Once removed, wait for any temporary
         * holds to be dropped before actually destroying the resource.
         */
        lwkt_gettoken(&rman_tok);
        TAILQ_REMOVE(&rman_head, rm, rm_link);
        lwkt_reltoken(&rman_tok);

        if (rm->rm_hold) {
                kprintf("debug: rman_fini(): rm_hold race fixed on %s\n",
                        rm->rm_descr);
                while (rm->rm_hold)
                        tsleep(rm, 0, "rmfree", 2);
        }

        /*
         * Destroy all elements remaining on rm_list
         */
        while ((r = TAILQ_FIRST(&rm->rm_list)) != NULL) {
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
                kfree(r, M_RMAN);
        }
        lwkt_reltoken(rm->rm_slock);

        /*
         * Final cleanup
         */
        lwkt_token_uninit(rm->rm_slock);
        kfree(rm->rm_slock, M_RMAN);
        rm->rm_slock = NULL;

        return 0;
}

struct resource *
rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
                      u_int flags, device_t dev)
{
        u_int   want_activate;
        struct  resource *r, *s, *rv;
        u_long  rstart, rend;

        rv = NULL;

        DPRINTF(("rman_reserve_resource: <%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)));
        want_activate = (flags & RF_ACTIVE);
        flags &= ~RF_ACTIVE;

        lwkt_gettoken(rm->rm_slock);

        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;
        }

        /*
         * 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));
                if (s->r_start > end - (count - 1)) {
                        DPRINTF(("s->r_start (%#lx) > end (%#lx)\n",
                            s->r_start, end));
                        break;
                }
                if (s->r_flags & RF_ALLOCATED) {
                        DPRINTF(("region is allocated\n"));
                        continue;
                }
                rstart = ulmax(s->r_start, start);
                rstart = rounddown2(rstart + (1ul << RF_ALIGNMENT(flags)) - 1,
                    1ul << RF_ALIGNMENT(flags));
                rend = ulmin(s->r_end, ulmax(start + count - 1, end));
                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 |= RF_ALLOCATED | flags;
                                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 = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
                        if (rv == NULL)
                                goto out;
                        rv->r_start = rstart;
                        rv->r_end = rstart + count - 1;
                        rv->r_flags = flags | RF_ALLOCATED;
                        rv->r_dev = dev;
                        rv->r_sharehead = 0;
                        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 = kmalloc(sizeof *r, M_RMAN,
                                    M_NOWAIT | M_ZERO);
                                if (r == NULL) {
                                        kfree(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_dev = 0;
                                r->r_sharehead = 0;
                                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 | RF_TIMESHARE)) == 0)
                goto out;

        for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
                if (s->r_start > end)
                        break;
                if ((s->r_flags & flags) != flags)
                        continue;
                rstart = ulmax(s->r_start, start);
                rend = ulmin(s->r_end, ulmax(start + count, end));
                if (s->r_start >= start && s->r_end <= end
                    && (s->r_end - s->r_start + 1) == count) {
                        rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
                        if (rv == NULL)
                                goto out;
                        rv->r_start = s->r_start;
                        rv->r_end = s->r_end;
                        rv->r_flags = s->r_flags & 
                                (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
                        rv->r_dev = dev;
                        rv->r_rm = rm;
                        if (s->r_sharehead == 0) {
                                s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
                                                        M_RMAN,
                                                        M_NOWAIT | M_ZERO);
                                if (s->r_sharehead == 0) {
                                        kfree(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.
         */
        DPRINTF(("no region found\n"));
out:
        /*
         * If the user specified RF_ACTIVE in the initial flags,
         * which is reflected in `want_activate', we attempt to atomically
         * activate the resource.  If this fails, we release the resource
         * and indicate overall failure.  (This behavior probably doesn't
         * make sense for RF_TIMESHARE-type resources.)
         */
        if (rv && want_activate) {
                struct resource *whohas;
                DPRINTF(("activating region\n"));
                if (int_rman_activate_resource(rm, rv, &whohas)) {
                        int_rman_release_resource(rm, rv);
                        rv = NULL;
                }
        }
        lwkt_reltoken(rm->rm_slock);
        return (rv);
}

static int
int_rman_activate_resource(struct rman *rm, struct resource *r,
                           struct resource **whohas)
{
        struct resource *s;
        int ok;

        /*
         * If we are not timesharing, then there is nothing much to do.
         * If we already have the resource, then there is nothing at all to do.
         * If we are not on a sharing list with anybody else, then there is
         * little to do.
         */
        if ((r->r_flags & RF_TIMESHARE) == 0
            || (r->r_flags & RF_ACTIVE) != 0
            || r->r_sharehead == 0) {
                r->r_flags |= RF_ACTIVE;
                return 0;
        }

        ok = 1;
        for (s = LIST_FIRST(r->r_sharehead); s && ok;
             s = LIST_NEXT(s, r_sharelink)) {
                if ((s->r_flags & RF_ACTIVE) != 0) {
                        ok = 0;
                        *whohas = s;
                }
        }
        if (ok) {
                r->r_flags |= RF_ACTIVE;
                return 0;
        }
        return EBUSY;
}

int
rman_activate_resource(struct resource *r)
{
        int rv;
        struct resource *whohas;
        struct rman *rm;

        rm = r->r_rm;
        lwkt_gettoken(rm->rm_slock);
        rv = int_rman_activate_resource(rm, r, &whohas);
        lwkt_reltoken(rm->rm_slock);
        return rv;
}

#if 0

/* XXX */
int
rman_await_resource(struct resource *r, int slpflags, int timo)
{
        int     rv;
        struct  resource *whohas;
        struct  rman *rm;

        rm = r->r_rm;
        for (;;) {
                lwkt_gettoken(rm->rm_slock);
                rv = int_rman_activate_resource(rm, r, &whohas);
                if (rv != EBUSY)
                        return (rv);    /* returns with ilock held */

                if (r->r_sharehead == 0)
                        panic("rman_await_resource");
                /*
                 * A critical section will hopefully will prevent a race 
                 * between lwkt_reltoken and tsleep where a process
                 * could conceivably get in and release the resource
                 * before we have a chance to sleep on it. YYY
                 */
                crit_enter();
                whohas->r_flags |= RF_WANTED;
                rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
                if (rv) {
                        lwkt_reltoken(rm->rm_slock);
                        crit_exit();
                        return rv;
                }
                crit_exit();
        }
}

#endif

static int
int_rman_deactivate_resource(struct resource *r)
{
        r->r_flags &= ~RF_ACTIVE;
        if (r->r_flags & RF_WANTED) {
                r->r_flags &= ~RF_WANTED;
                wakeup(r->r_sharehead);
        }
        return 0;
}

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

        rm = r->r_rm;
        lwkt_gettoken(rm->rm_slock);
        int_rman_deactivate_resource(r);
        lwkt_reltoken(rm->rm_slock);
        return 0;
}

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

        if (r->r_flags & RF_ACTIVE)
                int_rman_deactivate_resource(r);

        /*
         * 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) == 0) {
                        kfree(s->r_sharehead, M_RMAN);
                        s->r_sharehead = 0;
                        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.
         */
        s = TAILQ_PREV(r, resource_head, r_link);
        t = TAILQ_NEXT(r, r_link);

        if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0
            && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
                /*
                 * 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);
                kfree(t, M_RMAN);
        } else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) {
                /*
                 * Merge previous segment with ours.
                 */
                s->r_end = r->r_end;
                TAILQ_REMOVE(&rm->rm_list, r, r_link);
        } else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
                /*
                 * 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;
                return 0;
        }

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

int
rman_release_resource(struct resource *r)
{
        struct  rman *rm = r->r_rm;
        int     rv;

        lwkt_gettoken(rm->rm_slock);
        rv = int_rman_release_resource(rm, r);
        lwkt_reltoken(rm->rm_slock);
        return (rv);
}

/*
 * Find the hightest bit set, and add one if more than one bit
 * set.  We're effectively computing the ceil(log2(size)) here.
 *
 * This function cannot compute alignments above (1LU<<63)+1
 * as this would require returning '64' which will not fit in
 * the flags field and doesn't work well for calculations either.
 */
uint32_t
rman_make_alignment_flags(size_t size)
{
        int i;

        for (i = 63; i; --i) {
                if ((1LU << i) & size)
                        break;
        }
        if (~(1LU << i) & size)
                ++i;
        if (i == 64)
                i = 63;
        return(RF_ALIGNMENT_LOG2(i));
}

/*
 * 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         *res;
        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
         */
        error = ENOENT;
        lwkt_gettoken(&rman_tok);

        TAILQ_FOREACH(rm, &rman_head, rm_link) {
                if (rman_idx-- == 0)
                        break;
        }
        if (rm == NULL)
                goto done;

        /*
         * If the resource index is -1, we want details on the
         * resource manager.
         */
        if (res_idx == -1) {
                urm.rm_handle = (uintptr_t)rm;
                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;
                urm.rm_cpuid = rm->rm_cpuid;

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

        /*
         * Find the indexed resource and return it.
         */
        atomic_add_int(&rm->rm_hold, 1);        /* temp prevent destruction */
        lwkt_gettoken(rm->rm_slock);

        TAILQ_FOREACH(res, &rm->rm_list, r_link) {
                if (res_idx-- == 0) {
                        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) {
                                        ksnprintf(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;

                        error = SYSCTL_OUT(req, &ures, sizeof(ures));
                        break;
                }
        }
        lwkt_reltoken(rm->rm_slock);
        atomic_add_int(&rm->rm_hold, -1);
done:
        lwkt_reltoken(&rman_tok);

        return (error);
}

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