USB: serial: mos7720: fix non-atomic allocation in write path

[linux/fpc-iii.git] / drivers / uwb / rsv.c

/*
 * UWB reservation management.
 *
 * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <linux/kernel.h>
#include <linux/uwb.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/export.h>

#include "uwb-internal.h"

static void uwb_rsv_timer(unsigned long arg);

static const char *rsv_states[] = {
        [UWB_RSV_STATE_NONE]                 = "none            ",
        [UWB_RSV_STATE_O_INITIATED]          = "o initiated     ",
        [UWB_RSV_STATE_O_PENDING]            = "o pending       ",
        [UWB_RSV_STATE_O_MODIFIED]           = "o modified      ",
        [UWB_RSV_STATE_O_ESTABLISHED]        = "o established   ",
        [UWB_RSV_STATE_O_TO_BE_MOVED]        = "o to be moved   ",
        [UWB_RSV_STATE_O_MOVE_EXPANDING]     = "o move expanding",
        [UWB_RSV_STATE_O_MOVE_COMBINING]     = "o move combining",
        [UWB_RSV_STATE_O_MOVE_REDUCING]      = "o move reducing ",
        [UWB_RSV_STATE_T_ACCEPTED]           = "t accepted      ",
        [UWB_RSV_STATE_T_CONFLICT]           = "t conflict      ",
        [UWB_RSV_STATE_T_PENDING]            = "t pending       ",
        [UWB_RSV_STATE_T_DENIED]             = "t denied        ",
        [UWB_RSV_STATE_T_RESIZED]            = "t resized       ",
        [UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = "t expanding acc ",
        [UWB_RSV_STATE_T_EXPANDING_CONFLICT] = "t expanding conf",
        [UWB_RSV_STATE_T_EXPANDING_PENDING]  = "t expanding pend",
        [UWB_RSV_STATE_T_EXPANDING_DENIED]   = "t expanding den ",
};

static const char *rsv_types[] = {
        [UWB_DRP_TYPE_ALIEN_BP] = "alien-bp",
        [UWB_DRP_TYPE_HARD]     = "hard",
        [UWB_DRP_TYPE_SOFT]     = "soft",
        [UWB_DRP_TYPE_PRIVATE]  = "private",
        [UWB_DRP_TYPE_PCA]      = "pca",
};

bool uwb_rsv_has_two_drp_ies(struct uwb_rsv *rsv)
{
        static const bool has_two_drp_ies[] = {
                [UWB_RSV_STATE_O_INITIATED]               = false,
                [UWB_RSV_STATE_O_PENDING]                 = false,
                [UWB_RSV_STATE_O_MODIFIED]                = false,
                [UWB_RSV_STATE_O_ESTABLISHED]             = false,
                [UWB_RSV_STATE_O_TO_BE_MOVED]             = false,
                [UWB_RSV_STATE_O_MOVE_COMBINING]          = false,
                [UWB_RSV_STATE_O_MOVE_REDUCING]           = false,
                [UWB_RSV_STATE_O_MOVE_EXPANDING]          = true,
                [UWB_RSV_STATE_T_ACCEPTED]                = false,
                [UWB_RSV_STATE_T_CONFLICT]                = false,
                [UWB_RSV_STATE_T_PENDING]                 = false,
                [UWB_RSV_STATE_T_DENIED]                  = false,
                [UWB_RSV_STATE_T_RESIZED]                 = false,
                [UWB_RSV_STATE_T_EXPANDING_ACCEPTED]      = true,
                [UWB_RSV_STATE_T_EXPANDING_CONFLICT]      = true,
                [UWB_RSV_STATE_T_EXPANDING_PENDING]       = true,
                [UWB_RSV_STATE_T_EXPANDING_DENIED]        = true,
        };

        return has_two_drp_ies[rsv->state];
}

/**
 * uwb_rsv_state_str - return a string for a reservation state
 * @state: the reservation state.
 */
const char *uwb_rsv_state_str(enum uwb_rsv_state state)
{
        if (state < UWB_RSV_STATE_NONE || state >= UWB_RSV_STATE_LAST)
                return "unknown";
        return rsv_states[state];
}
EXPORT_SYMBOL_GPL(uwb_rsv_state_str);

/**
 * uwb_rsv_type_str - return a string for a reservation type
 * @type: the reservation type
 */
const char *uwb_rsv_type_str(enum uwb_drp_type type)
{
        if (type < UWB_DRP_TYPE_ALIEN_BP || type > UWB_DRP_TYPE_PCA)
                return "invalid";
        return rsv_types[type];
}
EXPORT_SYMBOL_GPL(uwb_rsv_type_str);

void uwb_rsv_dump(char *text, struct uwb_rsv *rsv)
{
        struct device *dev = &rsv->rc->uwb_dev.dev;
        struct uwb_dev_addr devaddr;
        char owner[UWB_ADDR_STRSIZE], target[UWB_ADDR_STRSIZE];

        uwb_dev_addr_print(owner, sizeof(owner), &rsv->owner->dev_addr);
        if (rsv->target.type == UWB_RSV_TARGET_DEV)
                devaddr = rsv->target.dev->dev_addr;
        else
                devaddr = rsv->target.devaddr;
        uwb_dev_addr_print(target, sizeof(target), &devaddr);

        dev_dbg(dev, "rsv %s %s -> %s: %s\n",
                text, owner, target, uwb_rsv_state_str(rsv->state));
}

static void uwb_rsv_release(struct kref *kref)
{
        struct uwb_rsv *rsv = container_of(kref, struct uwb_rsv, kref);

        kfree(rsv);
}

void uwb_rsv_get(struct uwb_rsv *rsv)
{
        kref_get(&rsv->kref);
}

void uwb_rsv_put(struct uwb_rsv *rsv)
{
        kref_put(&rsv->kref, uwb_rsv_release);
}

/*
 * Get a free stream index for a reservation.
 *
 * If the target is a DevAddr (e.g., a WUSB cluster reservation) then
 * the stream is allocated from a pool of per-RC stream indexes,
 * otherwise a unique stream index for the target is selected.
 */
static int uwb_rsv_get_stream(struct uwb_rsv *rsv)
{
        struct uwb_rc *rc = rsv->rc;
        struct device *dev = &rc->uwb_dev.dev;
        unsigned long *streams_bm;
        int stream;

        switch (rsv->target.type) {
        case UWB_RSV_TARGET_DEV:
                streams_bm = rsv->target.dev->streams;
                break;
        case UWB_RSV_TARGET_DEVADDR:
                streams_bm = rc->uwb_dev.streams;
                break;
        default:
                return -EINVAL;
        }

        stream = find_first_zero_bit(streams_bm, UWB_NUM_STREAMS);
        if (stream >= UWB_NUM_STREAMS) {
                dev_err(dev, "%s: no available stream found\n", __func__);
                return -EBUSY;
        }

        rsv->stream = stream;
        set_bit(stream, streams_bm);

        dev_dbg(dev, "get stream %d\n", rsv->stream);

        return 0;
}

static void uwb_rsv_put_stream(struct uwb_rsv *rsv)
{
        struct uwb_rc *rc = rsv->rc;
        struct device *dev = &rc->uwb_dev.dev;
        unsigned long *streams_bm;

        switch (rsv->target.type) {
        case UWB_RSV_TARGET_DEV:
                streams_bm = rsv->target.dev->streams;
                break;
        case UWB_RSV_TARGET_DEVADDR:
                streams_bm = rc->uwb_dev.streams;
                break;
        default:
                return;
        }

        clear_bit(rsv->stream, streams_bm);

        dev_dbg(dev, "put stream %d\n", rsv->stream);
}

void uwb_rsv_backoff_win_timer(unsigned long arg)
{
        struct uwb_drp_backoff_win *bow = (struct uwb_drp_backoff_win *)arg;
        struct uwb_rc *rc = container_of(bow, struct uwb_rc, bow);
        struct device *dev = &rc->uwb_dev.dev;

        bow->can_reserve_extra_mases = true;
        if (bow->total_expired <= 4) {
                bow->total_expired++;
        } else {
                /* after 4 backoff window has expired we can exit from
                 * the backoff procedure */
                bow->total_expired = 0;
                bow->window = UWB_DRP_BACKOFF_WIN_MIN >> 1;
        }
        dev_dbg(dev, "backoff_win_timer total_expired=%d, n=%d\n", bow->total_expired, bow->n);

        /* try to relocate all the "to be moved" relocations */
        uwb_rsv_handle_drp_avail_change(rc);
}

void uwb_rsv_backoff_win_increment(struct uwb_rc *rc)
{
        struct uwb_drp_backoff_win *bow = &rc->bow;
        struct device *dev = &rc->uwb_dev.dev;
        unsigned timeout_us;

        dev_dbg(dev, "backoff_win_increment: window=%d\n", bow->window);

        bow->can_reserve_extra_mases = false;

        if((bow->window << 1) == UWB_DRP_BACKOFF_WIN_MAX)
                return;

        bow->window <<= 1;
        bow->n = prandom_u32() & (bow->window - 1);
        dev_dbg(dev, "new_window=%d, n=%d\n", bow->window, bow->n);

        /* reset the timer associated variables */
        timeout_us = bow->n * UWB_SUPERFRAME_LENGTH_US;
        bow->total_expired = 0;
        mod_timer(&bow->timer, jiffies + usecs_to_jiffies(timeout_us));
}

static void uwb_rsv_stroke_timer(struct uwb_rsv *rsv)
{
        int sframes = UWB_MAX_LOST_BEACONS;

        /*
         * Multicast reservations can become established within 1
         * super frame and should not be terminated if no response is
         * received.
         */
        if (rsv->state == UWB_RSV_STATE_NONE) {
                sframes = 0;
        } else if (rsv->is_multicast) {
                if (rsv->state == UWB_RSV_STATE_O_INITIATED
                    || rsv->state == UWB_RSV_STATE_O_MOVE_EXPANDING
                    || rsv->state == UWB_RSV_STATE_O_MOVE_COMBINING
                    || rsv->state == UWB_RSV_STATE_O_MOVE_REDUCING)
                        sframes = 1;
                if (rsv->state == UWB_RSV_STATE_O_ESTABLISHED)
                        sframes = 0;

        }

        if (sframes > 0) {
                /*
                 * Add an additional 2 superframes to account for the
                 * time to send the SET DRP IE command.
                 */
                unsigned timeout_us = (sframes + 2) * UWB_SUPERFRAME_LENGTH_US;
                mod_timer(&rsv->timer, jiffies + usecs_to_jiffies(timeout_us));
        } else
                del_timer(&rsv->timer);
}

/*
 * Update a reservations state, and schedule an update of the
 * transmitted DRP IEs.
 */
static void uwb_rsv_state_update(struct uwb_rsv *rsv,
                                 enum uwb_rsv_state new_state)
{
        rsv->state = new_state;
        rsv->ie_valid = false;

        uwb_rsv_dump("SU", rsv);

        uwb_rsv_stroke_timer(rsv);
        uwb_rsv_sched_update(rsv->rc);
}

static void uwb_rsv_callback(struct uwb_rsv *rsv)
{
        if (rsv->callback)
                rsv->callback(rsv);
}

void uwb_rsv_set_state(struct uwb_rsv *rsv, enum uwb_rsv_state new_state)
{
        struct uwb_rsv_move *mv = &rsv->mv;

        if (rsv->state == new_state) {
                switch (rsv->state) {
                case UWB_RSV_STATE_O_ESTABLISHED:
                case UWB_RSV_STATE_O_MOVE_EXPANDING:
                case UWB_RSV_STATE_O_MOVE_COMBINING:
                case UWB_RSV_STATE_O_MOVE_REDUCING:
                case UWB_RSV_STATE_T_ACCEPTED:
                case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
                case UWB_RSV_STATE_T_RESIZED:
                case UWB_RSV_STATE_NONE:
                        uwb_rsv_stroke_timer(rsv);
                        break;
                default:
                        /* Expecting a state transition so leave timer
                           as-is. */
                        break;
                }
                return;
        }

        uwb_rsv_dump("SC", rsv);

        switch (new_state) {
        case UWB_RSV_STATE_NONE:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_NONE);
                uwb_rsv_remove(rsv);
                uwb_rsv_callback(rsv);
                break;
        case UWB_RSV_STATE_O_INITIATED:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_INITIATED);
                break;
        case UWB_RSV_STATE_O_PENDING:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_PENDING);
                break;
        case UWB_RSV_STATE_O_MODIFIED:
                /* in the companion there are the MASes to drop */
                bitmap_andnot(rsv->mas.bm, rsv->mas.bm, mv->companion_mas.bm, UWB_NUM_MAS);
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MODIFIED);
                break;
        case UWB_RSV_STATE_O_ESTABLISHED:
                if (rsv->state == UWB_RSV_STATE_O_MODIFIED
                    || rsv->state == UWB_RSV_STATE_O_MOVE_REDUCING) {
                        uwb_drp_avail_release(rsv->rc, &mv->companion_mas);
                        rsv->needs_release_companion_mas = false;
                }
                uwb_drp_avail_reserve(rsv->rc, &rsv->mas);
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                uwb_rsv_callback(rsv);
                break;
        case UWB_RSV_STATE_O_MOVE_EXPANDING:
                rsv->needs_release_companion_mas = true;
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
                break;
        case UWB_RSV_STATE_O_MOVE_COMBINING:
                rsv->needs_release_companion_mas = false;
                uwb_drp_avail_reserve(rsv->rc, &mv->companion_mas);
                bitmap_or(rsv->mas.bm, rsv->mas.bm, mv->companion_mas.bm, UWB_NUM_MAS);
                rsv->mas.safe   += mv->companion_mas.safe;
                rsv->mas.unsafe += mv->companion_mas.unsafe;
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
                break;
        case UWB_RSV_STATE_O_MOVE_REDUCING:
                bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS);
                rsv->needs_release_companion_mas = true;
                rsv->mas.safe   = mv->final_mas.safe;
                rsv->mas.unsafe = mv->final_mas.unsafe;
                bitmap_copy(rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS);
                bitmap_copy(rsv->mas.unsafe_bm, mv->final_mas.unsafe_bm, UWB_NUM_MAS);
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
                break;
        case UWB_RSV_STATE_T_ACCEPTED:
        case UWB_RSV_STATE_T_RESIZED:
                rsv->needs_release_companion_mas = false;
                uwb_drp_avail_reserve(rsv->rc, &rsv->mas);
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_ACCEPTED);
                uwb_rsv_callback(rsv);
                break;
        case UWB_RSV_STATE_T_DENIED:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_DENIED);
                break;
        case UWB_RSV_STATE_T_CONFLICT:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_CONFLICT);
                break;
        case UWB_RSV_STATE_T_PENDING:
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_PENDING);
                break;
        case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
                rsv->needs_release_companion_mas = true;
                uwb_drp_avail_reserve(rsv->rc, &mv->companion_mas);
                uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_EXPANDING_ACCEPTED);
                break;
        default:
                dev_err(&rsv->rc->uwb_dev.dev, "unhandled state: %s (%d)\n",
                        uwb_rsv_state_str(new_state), new_state);
        }
}

static void uwb_rsv_handle_timeout_work(struct work_struct *work)
{
        struct uwb_rsv *rsv = container_of(work, struct uwb_rsv,
                                           handle_timeout_work);
        struct uwb_rc *rc = rsv->rc;

        mutex_lock(&rc->rsvs_mutex);

        uwb_rsv_dump("TO", rsv);

        switch (rsv->state) {
        case UWB_RSV_STATE_O_INITIATED:
                if (rsv->is_multicast) {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                        goto unlock;
                }
                break;
        case UWB_RSV_STATE_O_MOVE_EXPANDING:
                if (rsv->is_multicast) {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
                        goto unlock;
                }
                break;
        case UWB_RSV_STATE_O_MOVE_COMBINING:
                if (rsv->is_multicast) {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
                        goto unlock;
                }
                break;
        case UWB_RSV_STATE_O_MOVE_REDUCING:
                if (rsv->is_multicast) {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                        goto unlock;
                }
                break;
        case UWB_RSV_STATE_O_ESTABLISHED:
                if (rsv->is_multicast)
                        goto unlock;
                break;
        case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
                /*
                 * The time out could be for the main or of the
                 * companion DRP, assume it's for the companion and
                 * drop that first.  A further time out is required to
                 * drop the main.
                 */
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
                uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
                goto unlock;
        case UWB_RSV_STATE_NONE:
                goto unlock;
        default:
                break;
        }

        uwb_rsv_remove(rsv);

unlock:
        mutex_unlock(&rc->rsvs_mutex);
}

static struct uwb_rsv *uwb_rsv_alloc(struct uwb_rc *rc)
{
        struct uwb_rsv *rsv;

        rsv = kzalloc(sizeof(struct uwb_rsv), GFP_KERNEL);
        if (!rsv)
                return NULL;

        INIT_LIST_HEAD(&rsv->rc_node);
        INIT_LIST_HEAD(&rsv->pal_node);
        kref_init(&rsv->kref);
        setup_timer(&rsv->timer, uwb_rsv_timer, (unsigned long)rsv);

        rsv->rc = rc;
        INIT_WORK(&rsv->handle_timeout_work, uwb_rsv_handle_timeout_work);

        return rsv;
}

/**
 * uwb_rsv_create - allocate and initialize a UWB reservation structure
 * @rc: the radio controller
 * @cb: callback to use when the reservation completes or terminates
 * @pal_priv: data private to the PAL to be passed in the callback
 *
 * The callback is called when the state of the reservation changes from:
 *
 *   - pending to accepted
 *   - pending to denined
 *   - accepted to terminated
 *   - pending to terminated
 */
struct uwb_rsv *uwb_rsv_create(struct uwb_rc *rc, uwb_rsv_cb_f cb, void *pal_priv)
{
        struct uwb_rsv *rsv;

        rsv = uwb_rsv_alloc(rc);
        if (!rsv)
                return NULL;

        rsv->callback = cb;
        rsv->pal_priv = pal_priv;

        return rsv;
}
EXPORT_SYMBOL_GPL(uwb_rsv_create);

void uwb_rsv_remove(struct uwb_rsv *rsv)
{
        uwb_rsv_dump("RM", rsv);

        if (rsv->state != UWB_RSV_STATE_NONE)
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);

        if (rsv->needs_release_companion_mas)
                uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
        uwb_drp_avail_release(rsv->rc, &rsv->mas);

        if (uwb_rsv_is_owner(rsv))
                uwb_rsv_put_stream(rsv);

        uwb_dev_put(rsv->owner);
        if (rsv->target.type == UWB_RSV_TARGET_DEV)
                uwb_dev_put(rsv->target.dev);

        list_del_init(&rsv->rc_node);
        uwb_rsv_put(rsv);
}

/**
 * uwb_rsv_destroy - free a UWB reservation structure
 * @rsv: the reservation to free
 *
 * The reservation must already be terminated.
 */
void uwb_rsv_destroy(struct uwb_rsv *rsv)
{
        uwb_rsv_put(rsv);
}
EXPORT_SYMBOL_GPL(uwb_rsv_destroy);

/**
 * usb_rsv_establish - start a reservation establishment
 * @rsv: the reservation
 *
 * The PAL should fill in @rsv's owner, target, type, max_mas,
 * min_mas, max_interval and is_multicast fields.  If the target is a
 * uwb_dev it must be referenced.
 *
 * The reservation's callback will be called when the reservation is
 * accepted, denied or times out.
 */
int uwb_rsv_establish(struct uwb_rsv *rsv)
{
        struct uwb_rc *rc = rsv->rc;
        struct uwb_mas_bm available;
        struct device *dev = &rc->uwb_dev.dev;
        int ret;

        mutex_lock(&rc->rsvs_mutex);
        ret = uwb_rsv_get_stream(rsv);
        if (ret) {
                dev_err(dev, "%s: uwb_rsv_get_stream failed: %d\n",
                        __func__, ret);
                goto out;
        }

        rsv->tiebreaker = prandom_u32() & 1;
        /* get available mas bitmap */
        uwb_drp_available(rc, &available);

        ret = uwb_rsv_find_best_allocation(rsv, &available, &rsv->mas);
        if (ret == UWB_RSV_ALLOC_NOT_FOUND) {
                ret = -EBUSY;
                uwb_rsv_put_stream(rsv);
                dev_err(dev, "%s: uwb_rsv_find_best_allocation failed: %d\n",
                        __func__, ret);
                goto out;
        }

        ret = uwb_drp_avail_reserve_pending(rc, &rsv->mas);
        if (ret != 0) {
                uwb_rsv_put_stream(rsv);
                dev_err(dev, "%s: uwb_drp_avail_reserve_pending failed: %d\n",
                        __func__, ret);
                goto out;
        }

        uwb_rsv_get(rsv);
        list_add_tail(&rsv->rc_node, &rc->reservations);
        rsv->owner = &rc->uwb_dev;
        uwb_dev_get(rsv->owner);
        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_INITIATED);
out:
        mutex_unlock(&rc->rsvs_mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(uwb_rsv_establish);

/**
 * uwb_rsv_modify - modify an already established reservation
 * @rsv: the reservation to modify
 * @max_mas: new maximum MAS to reserve
 * @min_mas: new minimum MAS to reserve
 * @max_interval: new max_interval to use
 *
 * FIXME: implement this once there are PALs that use it.
 */
int uwb_rsv_modify(struct uwb_rsv *rsv, int max_mas, int min_mas, int max_interval)
{
        return -ENOSYS;
}
EXPORT_SYMBOL_GPL(uwb_rsv_modify);

/*
 * move an already established reservation (rc->rsvs_mutex must to be
 * taken when tis function is called)
 */
int uwb_rsv_try_move(struct uwb_rsv *rsv, struct uwb_mas_bm *available)
{
        struct uwb_rc *rc = rsv->rc;
        struct uwb_drp_backoff_win *bow = &rc->bow;
        struct device *dev = &rc->uwb_dev.dev;
        struct uwb_rsv_move *mv;
        int ret = 0;

        if (bow->can_reserve_extra_mases == false)
                return -EBUSY;

        mv = &rsv->mv;

        if (uwb_rsv_find_best_allocation(rsv, available, &mv->final_mas) == UWB_RSV_ALLOC_FOUND) {

                if (!bitmap_equal(rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS)) {
                        /* We want to move the reservation */
                        bitmap_andnot(mv->companion_mas.bm, mv->final_mas.bm, rsv->mas.bm, UWB_NUM_MAS);
                        uwb_drp_avail_reserve_pending(rc, &mv->companion_mas);
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
                }
        } else {
                dev_dbg(dev, "new allocation not found\n");
        }

        return ret;
}

/* It will try to move every reservation in state O_ESTABLISHED giving
 * to the MAS allocator algorithm an availability that is the real one
 * plus the allocation already established from the reservation. */
void uwb_rsv_handle_drp_avail_change(struct uwb_rc *rc)
{
        struct uwb_drp_backoff_win *bow = &rc->bow;
        struct uwb_rsv *rsv;
        struct uwb_mas_bm mas;

        if (bow->can_reserve_extra_mases == false)
                return;

        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                if (rsv->state == UWB_RSV_STATE_O_ESTABLISHED ||
                    rsv->state == UWB_RSV_STATE_O_TO_BE_MOVED) {
                        uwb_drp_available(rc, &mas);
                        bitmap_or(mas.bm, mas.bm, rsv->mas.bm, UWB_NUM_MAS);
                        uwb_rsv_try_move(rsv, &mas);
                }
        }

}

/**
 * uwb_rsv_terminate - terminate an established reservation
 * @rsv: the reservation to terminate
 *
 * A reservation is terminated by removing the DRP IE from the beacon,
 * the other end will consider the reservation to be terminated when
 * it does not see the DRP IE for at least mMaxLostBeacons.
 *
 * If applicable, the reference to the target uwb_dev will be released.
 */
void uwb_rsv_terminate(struct uwb_rsv *rsv)
{
        struct uwb_rc *rc = rsv->rc;

        mutex_lock(&rc->rsvs_mutex);

        if (rsv->state != UWB_RSV_STATE_NONE)
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);

        mutex_unlock(&rc->rsvs_mutex);
}
EXPORT_SYMBOL_GPL(uwb_rsv_terminate);

/**
 * uwb_rsv_accept - accept a new reservation from a peer
 * @rsv:      the reservation
 * @cb:       call back for reservation changes
 * @pal_priv: data to be passed in the above call back
 *
 * Reservation requests from peers are denied unless a PAL accepts it
 * by calling this function.
 *
 * The PAL call uwb_rsv_destroy() for all accepted reservations before
 * calling uwb_pal_unregister().
 */
void uwb_rsv_accept(struct uwb_rsv *rsv, uwb_rsv_cb_f cb, void *pal_priv)
{
        uwb_rsv_get(rsv);

        rsv->callback = cb;
        rsv->pal_priv = pal_priv;
        rsv->state    = UWB_RSV_STATE_T_ACCEPTED;
}
EXPORT_SYMBOL_GPL(uwb_rsv_accept);

/*
 * Is a received DRP IE for this reservation?
 */
static bool uwb_rsv_match(struct uwb_rsv *rsv, struct uwb_dev *src,
                          struct uwb_ie_drp *drp_ie)
{
        struct uwb_dev_addr *rsv_src;
        int stream;

        stream = uwb_ie_drp_stream_index(drp_ie);

        if (rsv->stream != stream)
                return false;

        switch (rsv->target.type) {
        case UWB_RSV_TARGET_DEVADDR:
                return rsv->stream == stream;
        case UWB_RSV_TARGET_DEV:
                if (uwb_ie_drp_owner(drp_ie))
                        rsv_src = &rsv->owner->dev_addr;
                else
                        rsv_src = &rsv->target.dev->dev_addr;
                return uwb_dev_addr_cmp(&src->dev_addr, rsv_src) == 0;
        }
        return false;
}

static struct uwb_rsv *uwb_rsv_new_target(struct uwb_rc *rc,
                                          struct uwb_dev *src,
                                          struct uwb_ie_drp *drp_ie)
{
        struct uwb_rsv *rsv;
        struct uwb_pal *pal;
        enum uwb_rsv_state state;

        rsv = uwb_rsv_alloc(rc);
        if (!rsv)
                return NULL;

        rsv->rc          = rc;
        rsv->owner       = src;
        uwb_dev_get(rsv->owner);
        rsv->target.type = UWB_RSV_TARGET_DEV;
        rsv->target.dev  = &rc->uwb_dev;
        uwb_dev_get(&rc->uwb_dev);
        rsv->type        = uwb_ie_drp_type(drp_ie);
        rsv->stream      = uwb_ie_drp_stream_index(drp_ie);
        uwb_drp_ie_to_bm(&rsv->mas, drp_ie);

        /*
         * See if any PALs are interested in this reservation. If not,
         * deny the request.
         */
        rsv->state = UWB_RSV_STATE_T_DENIED;
        mutex_lock(&rc->uwb_dev.mutex);
        list_for_each_entry(pal, &rc->pals, node) {
                if (pal->new_rsv)
                        pal->new_rsv(pal, rsv);
                if (rsv->state == UWB_RSV_STATE_T_ACCEPTED)
                        break;
        }
        mutex_unlock(&rc->uwb_dev.mutex);

        list_add_tail(&rsv->rc_node, &rc->reservations);
        state = rsv->state;
        rsv->state = UWB_RSV_STATE_NONE;

        /* FIXME: do something sensible here */
        if (state == UWB_RSV_STATE_T_ACCEPTED
            && uwb_drp_avail_reserve_pending(rc, &rsv->mas) == -EBUSY) {
                /* FIXME: do something sensible here */
        } else {
                uwb_rsv_set_state(rsv, state);
        }

        return rsv;
}

/**
 * uwb_rsv_get_usable_mas - get the bitmap of the usable MAS of a reservations
 * @rsv: the reservation.
 * @mas: returns the available MAS.
 *
 * The usable MAS of a reservation may be less than the negotiated MAS
 * if alien BPs are present.
 */
void uwb_rsv_get_usable_mas(struct uwb_rsv *rsv, struct uwb_mas_bm *mas)
{
        bitmap_zero(mas->bm, UWB_NUM_MAS);
        bitmap_andnot(mas->bm, rsv->mas.bm, rsv->rc->cnflt_alien_bitmap.bm, UWB_NUM_MAS);
}
EXPORT_SYMBOL_GPL(uwb_rsv_get_usable_mas);

/**
 * uwb_rsv_find - find a reservation for a received DRP IE.
 * @rc: the radio controller
 * @src: source of the DRP IE
 * @drp_ie: the DRP IE
 *
 * If the reservation cannot be found and the DRP IE is from a peer
 * attempting to establish a new reservation, create a new reservation
 * and add it to the list.
 */
struct uwb_rsv *uwb_rsv_find(struct uwb_rc *rc, struct uwb_dev *src,
                             struct uwb_ie_drp *drp_ie)
{
        struct uwb_rsv *rsv;

        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                if (uwb_rsv_match(rsv, src, drp_ie))
                        return rsv;
        }

        if (uwb_ie_drp_owner(drp_ie))
                return uwb_rsv_new_target(rc, src, drp_ie);

        return NULL;
}

/*
 * Go through all the reservations and check for timeouts and (if
 * necessary) update their DRP IEs.
 *
 * FIXME: look at building the SET_DRP_IE command here rather than
 * having to rescan the list in uwb_rc_send_all_drp_ie().
 */
static bool uwb_rsv_update_all(struct uwb_rc *rc)
{
        struct uwb_rsv *rsv, *t;
        bool ie_updated = false;

        list_for_each_entry_safe(rsv, t, &rc->reservations, rc_node) {
                if (!rsv->ie_valid) {
                        uwb_drp_ie_update(rsv);
                        ie_updated = true;
                }
        }

        return ie_updated;
}

void uwb_rsv_queue_update(struct uwb_rc *rc)
{
        unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;

        queue_delayed_work(rc->rsv_workq, &rc->rsv_update_work, usecs_to_jiffies(delay_us));
}

/**
 * uwb_rsv_sched_update - schedule an update of the DRP IEs
 * @rc: the radio controller.
 *
 * To improve performance and ensure correctness with [ECMA-368] the
 * number of SET-DRP-IE commands that are done are limited.
 *
 * DRP IEs update come from two sources: DRP events from the hardware
 * which all occur at the beginning of the superframe ('syncronous'
 * events) and reservation establishment/termination requests from
 * PALs or timers ('asynchronous' events).
 *
 * A delayed work ensures that all the synchronous events result in
 * one SET-DRP-IE command.
 *
 * Additional logic (the set_drp_ie_pending and rsv_updated_postponed
 * flags) will prevent an asynchrous event starting a SET-DRP-IE
 * command if one is currently awaiting a response.
 *
 * FIXME: this does leave a window where an asynchrous event can delay
 * the SET-DRP-IE for a synchronous event by one superframe.
 */
void uwb_rsv_sched_update(struct uwb_rc *rc)
{
        spin_lock_irq(&rc->rsvs_lock);
        if (!delayed_work_pending(&rc->rsv_update_work)) {
                if (rc->set_drp_ie_pending > 0) {
                        rc->set_drp_ie_pending++;
                        goto unlock;
                }
                uwb_rsv_queue_update(rc);
        }
unlock:
        spin_unlock_irq(&rc->rsvs_lock);
}

/*
 * Update DRP IEs and, if necessary, the DRP Availability IE and send
 * the updated IEs to the radio controller.
 */
static void uwb_rsv_update_work(struct work_struct *work)
{
        struct uwb_rc *rc = container_of(work, struct uwb_rc,
                                         rsv_update_work.work);
        bool ie_updated;

        mutex_lock(&rc->rsvs_mutex);

        ie_updated = uwb_rsv_update_all(rc);

        if (!rc->drp_avail.ie_valid) {
                uwb_drp_avail_ie_update(rc);
                ie_updated = true;
        }

        if (ie_updated && (rc->set_drp_ie_pending == 0))
                uwb_rc_send_all_drp_ie(rc);

        mutex_unlock(&rc->rsvs_mutex);
}

static void uwb_rsv_alien_bp_work(struct work_struct *work)
{
        struct uwb_rc *rc = container_of(work, struct uwb_rc,
                                         rsv_alien_bp_work.work);
        struct uwb_rsv *rsv;

        mutex_lock(&rc->rsvs_mutex);

        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                if (rsv->type != UWB_DRP_TYPE_ALIEN_BP) {
                        uwb_rsv_callback(rsv);
                }
        }

        mutex_unlock(&rc->rsvs_mutex);
}

static void uwb_rsv_timer(unsigned long arg)
{
        struct uwb_rsv *rsv = (struct uwb_rsv *)arg;

        queue_work(rsv->rc->rsv_workq, &rsv->handle_timeout_work);
}

/**
 * uwb_rsv_remove_all - remove all reservations
 * @rc: the radio controller
 *
 * A DRP IE update is not done.
 */
void uwb_rsv_remove_all(struct uwb_rc *rc)
{
        struct uwb_rsv *rsv, *t;

        mutex_lock(&rc->rsvs_mutex);
        list_for_each_entry_safe(rsv, t, &rc->reservations, rc_node) {
                if (rsv->state != UWB_RSV_STATE_NONE)
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
                del_timer_sync(&rsv->timer);
        }
        /* Cancel any postponed update. */
        rc->set_drp_ie_pending = 0;
        mutex_unlock(&rc->rsvs_mutex);

        cancel_delayed_work_sync(&rc->rsv_update_work);
        flush_workqueue(rc->rsv_workq);

        mutex_lock(&rc->rsvs_mutex);
        list_for_each_entry_safe(rsv, t, &rc->reservations, rc_node) {
                uwb_rsv_remove(rsv);
        }
        mutex_unlock(&rc->rsvs_mutex);
}

void uwb_rsv_init(struct uwb_rc *rc)
{
        INIT_LIST_HEAD(&rc->reservations);
        INIT_LIST_HEAD(&rc->cnflt_alien_list);
        mutex_init(&rc->rsvs_mutex);
        spin_lock_init(&rc->rsvs_lock);
        INIT_DELAYED_WORK(&rc->rsv_update_work, uwb_rsv_update_work);
        INIT_DELAYED_WORK(&rc->rsv_alien_bp_work, uwb_rsv_alien_bp_work);
        rc->bow.can_reserve_extra_mases = true;
        rc->bow.total_expired = 0;
        rc->bow.window = UWB_DRP_BACKOFF_WIN_MIN >> 1;
        setup_timer(&rc->bow.timer, uwb_rsv_backoff_win_timer,
                        (unsigned long)&rc->bow);

        bitmap_complement(rc->uwb_dev.streams, rc->uwb_dev.streams, UWB_NUM_STREAMS);
}

int uwb_rsv_setup(struct uwb_rc *rc)
{
        char name[16];

        snprintf(name, sizeof(name), "%s_rsvd", dev_name(&rc->uwb_dev.dev));
        rc->rsv_workq = create_singlethread_workqueue(name);
        if (rc->rsv_workq == NULL)
                return -ENOMEM;

        return 0;
}

void uwb_rsv_cleanup(struct uwb_rc *rc)
{
        uwb_rsv_remove_all(rc);
        destroy_workqueue(rc->rsv_workq);
}