treewide: remove redundant IS_ERR() before error code check

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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Ultra Wide Band
 * Dynamic Reservation Protocol handling
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
 */
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include "uwb-internal.h"


/* DRP Conflict Actions ([ECMA-368 2nd Edition] 17.4.6) */
enum uwb_drp_conflict_action {
        /* Reservation is maintained, no action needed */
        UWB_DRP_CONFLICT_MANTAIN = 0,

        /* the device shall not transmit frames in conflicting MASs in
         * the following superframe. If the device is the reservation
         * target, it shall also set the Reason Code in its DRP IE to
         * Conflict in its beacon in the following superframe.
         */
        UWB_DRP_CONFLICT_ACT1,

        /* the device shall not set the Reservation Status bit to ONE
         * and shall not transmit frames in conflicting MASs. If the
         * device is the reservation target, it shall also set the
         * Reason Code in its DRP IE to Conflict.
         */
        UWB_DRP_CONFLICT_ACT2,

        /* the device shall not transmit frames in conflicting MASs in
         * the following superframe. It shall remove the conflicting
         * MASs from the reservation or set the Reservation Status to
         * ZERO in its beacon in the following superframe. If the
         * device is the reservation target, it shall also set the
         * Reason Code in its DRP IE to Conflict.
         */
        UWB_DRP_CONFLICT_ACT3,
};


static void uwb_rc_set_drp_cmd_done(struct uwb_rc *rc, void *arg,
                                    struct uwb_rceb *reply, ssize_t reply_size)
{
        struct uwb_rc_evt_set_drp_ie *r = (struct uwb_rc_evt_set_drp_ie *)reply;
        unsigned long flags;

        if (r != NULL) {
                if (r->bResultCode != UWB_RC_RES_SUCCESS)
                        dev_err(&rc->uwb_dev.dev, "SET-DRP-IE failed: %s (%d)\n",
                                uwb_rc_strerror(r->bResultCode), r->bResultCode);
        } else
                dev_err(&rc->uwb_dev.dev, "SET-DRP-IE: timeout\n");

        spin_lock_irqsave(&rc->rsvs_lock, flags);
        if (rc->set_drp_ie_pending > 1) {
                rc->set_drp_ie_pending = 0;
                uwb_rsv_queue_update(rc);
        } else {
                rc->set_drp_ie_pending = 0;
        }
        spin_unlock_irqrestore(&rc->rsvs_lock, flags);
}

/**
 * Construct and send the SET DRP IE
 *
 * @rc:         UWB Host controller
 * @returns:    >= 0 number of bytes still available in the beacon
 *              < 0 errno code on error.
 *
 * See WUSB[8.6.2.7]: The host must set all the DRP IEs that it wants the
 * device to include in its beacon at the same time. We thus have to
 * traverse all reservations and include the DRP IEs of all PENDING
 * and NEGOTIATED reservations in a SET DRP command for transmission.
 *
 * A DRP Availability IE is appended.
 *
 * rc->rsvs_mutex is held
 *
 * FIXME We currently ignore the returned value indicating the remaining space
 * in beacon. This could be used to deny reservation requests earlier if
 * determined that they would cause the beacon space to be exceeded.
 */
int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
{
        int result;
        struct uwb_rc_cmd_set_drp_ie *cmd;
        struct uwb_rsv *rsv;
        struct uwb_rsv_move *mv;
        int num_bytes = 0;
        u8 *IEDataptr;

        result = -ENOMEM;
        /* First traverse all reservations to determine memory needed. */
        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                if (rsv->drp_ie != NULL) {
                        num_bytes += rsv->drp_ie->hdr.length + 2;
                        if (uwb_rsv_has_two_drp_ies(rsv) &&
                                (rsv->mv.companion_drp_ie != NULL)) {
                                mv = &rsv->mv;
                                num_bytes +=
                                        mv->companion_drp_ie->hdr.length + 2;
                        }
                }
        }
        num_bytes += sizeof(rc->drp_avail.ie);
        cmd = kzalloc(sizeof(*cmd) + num_bytes, GFP_KERNEL);
        if (cmd == NULL)
                goto error;
        cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
        cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_SET_DRP_IE);
        cmd->wIELength = num_bytes;
        IEDataptr = (u8 *)&cmd->IEData[0];

        /* FIXME: DRV avail IE is not always needed */
        /* put DRP avail IE first */
        memcpy(IEDataptr, &rc->drp_avail.ie, sizeof(rc->drp_avail.ie));
        IEDataptr += sizeof(struct uwb_ie_drp_avail);

        /* Next traverse all reservations to place IEs in allocated memory. */
        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                if (rsv->drp_ie != NULL) {
                        memcpy(IEDataptr, rsv->drp_ie,
                               rsv->drp_ie->hdr.length + 2);
                        IEDataptr += rsv->drp_ie->hdr.length + 2;

                        if (uwb_rsv_has_two_drp_ies(rsv) &&
                                (rsv->mv.companion_drp_ie != NULL)) {
                                mv = &rsv->mv;
                                memcpy(IEDataptr, mv->companion_drp_ie,
                                       mv->companion_drp_ie->hdr.length + 2);
                                IEDataptr +=
                                        mv->companion_drp_ie->hdr.length + 2;
                        }
                }
        }

        result = uwb_rc_cmd_async(rc, "SET-DRP-IE",
                                &cmd->rccb, sizeof(*cmd) + num_bytes,
                                UWB_RC_CET_GENERAL, UWB_RC_CMD_SET_DRP_IE,
                                uwb_rc_set_drp_cmd_done, NULL);

        rc->set_drp_ie_pending = 1;

        kfree(cmd);
error:
        return result;
}

/*
 * Evaluate the action to perform using conflict resolution rules
 *
 * Return a uwb_drp_conflict_action.
 */
static int evaluate_conflict_action(struct uwb_ie_drp *ext_drp_ie, int ext_beacon_slot,
                                    struct uwb_rsv *rsv, int our_status)
{
        int our_tie_breaker = rsv->tiebreaker;
        int our_type        = rsv->type;
        int our_beacon_slot = rsv->rc->uwb_dev.beacon_slot;

        int ext_tie_breaker = uwb_ie_drp_tiebreaker(ext_drp_ie);
        int ext_status      = uwb_ie_drp_status(ext_drp_ie);
        int ext_type        = uwb_ie_drp_type(ext_drp_ie);


        /* [ECMA-368 2nd Edition] 17.4.6 */
        if (ext_type == UWB_DRP_TYPE_PCA && our_type == UWB_DRP_TYPE_PCA) {
                return UWB_DRP_CONFLICT_MANTAIN;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-1 */
        if (our_type == UWB_DRP_TYPE_ALIEN_BP) {
                return UWB_DRP_CONFLICT_MANTAIN;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-2 */
        if (ext_type == UWB_DRP_TYPE_ALIEN_BP) {
                /* here we know our_type != UWB_DRP_TYPE_ALIEN_BP */
                return UWB_DRP_CONFLICT_ACT1;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-3 */
        if (our_status == 0 && ext_status == 1) {
                return UWB_DRP_CONFLICT_ACT2;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-4 */
        if (our_status == 1 && ext_status == 0) {
                return UWB_DRP_CONFLICT_MANTAIN;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-5a */
        if (our_tie_breaker == ext_tie_breaker &&
            our_beacon_slot <  ext_beacon_slot) {
                return UWB_DRP_CONFLICT_MANTAIN;
        }

        /* [ECMA-368 2nd Edition] 17.4.6-5b */
        if (our_tie_breaker != ext_tie_breaker &&
            our_beacon_slot >  ext_beacon_slot) {
                return UWB_DRP_CONFLICT_MANTAIN;
        }

        if (our_status == 0) {
                if (our_tie_breaker == ext_tie_breaker) {
                        /* [ECMA-368 2nd Edition] 17.4.6-6a */
                        if (our_beacon_slot > ext_beacon_slot) {
                                return UWB_DRP_CONFLICT_ACT2;
                        }
                } else  {
                        /* [ECMA-368 2nd Edition] 17.4.6-6b */
                        if (our_beacon_slot < ext_beacon_slot) {
                                return UWB_DRP_CONFLICT_ACT2;
                        }
                }
        } else {
                if (our_tie_breaker == ext_tie_breaker) {
                        /* [ECMA-368 2nd Edition] 17.4.6-7a */
                        if (our_beacon_slot > ext_beacon_slot) {
                                return UWB_DRP_CONFLICT_ACT3;
                        }
                } else {
                        /* [ECMA-368 2nd Edition] 17.4.6-7b */
                        if (our_beacon_slot < ext_beacon_slot) {
                                return UWB_DRP_CONFLICT_ACT3;
                        }
                }
        }
        return UWB_DRP_CONFLICT_MANTAIN;
}

static void handle_conflict_normal(struct uwb_ie_drp *drp_ie,
                                   int ext_beacon_slot,
                                   struct uwb_rsv *rsv,
                                   struct uwb_mas_bm *conflicting_mas)
{
        struct uwb_rc *rc = rsv->rc;
        struct uwb_rsv_move *mv = &rsv->mv;
        struct uwb_drp_backoff_win *bow = &rc->bow;
        int action;

        action = evaluate_conflict_action(drp_ie, ext_beacon_slot, rsv, uwb_rsv_status(rsv));

        if (uwb_rsv_is_owner(rsv)) {
                switch(action) {
                case UWB_DRP_CONFLICT_ACT2:
                        /* try move */
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_TO_BE_MOVED);
                        if (bow->can_reserve_extra_mases == false)
                                uwb_rsv_backoff_win_increment(rc);

                        break;
                case UWB_DRP_CONFLICT_ACT3:
                        uwb_rsv_backoff_win_increment(rc);
                        /* drop some mases with reason modified */
                        /* put in the companion the mases to be dropped */
                        bitmap_and(mv->companion_mas.bm, rsv->mas.bm, conflicting_mas->bm, UWB_NUM_MAS);
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);
                default:
                        break;
                }
        } else {
                switch(action) {
                case UWB_DRP_CONFLICT_ACT2:
                case UWB_DRP_CONFLICT_ACT3:
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
                default:
                        break;
                }

        }

}

static void handle_conflict_expanding(struct uwb_ie_drp *drp_ie, int ext_beacon_slot,
                                      struct uwb_rsv *rsv, bool companion_only,
                                      struct uwb_mas_bm *conflicting_mas)
{
        struct uwb_rc *rc = rsv->rc;
        struct uwb_drp_backoff_win *bow = &rc->bow;
        struct uwb_rsv_move *mv = &rsv->mv;
        int action;

        if (companion_only) {
                /* status of companion is 0 at this point */
                action = evaluate_conflict_action(drp_ie, ext_beacon_slot, rsv, 0);
                if (uwb_rsv_is_owner(rsv)) {
                        switch(action) {
                        case UWB_DRP_CONFLICT_ACT2:
                        case UWB_DRP_CONFLICT_ACT3:
                                uwb_rsv_set_state(rsv,
                                                UWB_RSV_STATE_O_ESTABLISHED);
                                rsv->needs_release_companion_mas = false;
                                if (bow->can_reserve_extra_mases == false)
                                        uwb_rsv_backoff_win_increment(rc);
                                uwb_drp_avail_release(rsv->rc,
                                                &rsv->mv.companion_mas);
                        }
                } else { /* rsv is target */
                        switch(action) {
                        case UWB_DRP_CONFLICT_ACT2:
                        case UWB_DRP_CONFLICT_ACT3:
                                uwb_rsv_set_state(rsv,
                                        UWB_RSV_STATE_T_EXPANDING_CONFLICT);
                                /* send_drp_avail_ie = true; */
                        }
                }
        } else { /* also base part of the reservation is conflicting */
                if (uwb_rsv_is_owner(rsv)) {
                        uwb_rsv_backoff_win_increment(rc);
                        /* remove companion part */
                        uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);

                        /* drop some mases with reason modified */

                        /* put in the companion the mases to be dropped */
                        bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm,
                                        conflicting_mas->bm, UWB_NUM_MAS);
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);
                } else { /* it is a target rsv */
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
                        /* send_drp_avail_ie = true; */
                }
        }
}

static void uwb_drp_handle_conflict_rsv(struct uwb_rc *rc, struct uwb_rsv *rsv,
                                        struct uwb_rc_evt_drp *drp_evt,
                                        struct uwb_ie_drp *drp_ie,
                                        struct uwb_mas_bm *conflicting_mas)
{
        struct uwb_rsv_move *mv;

        /* check if the conflicting reservation has two drp_ies */
        if (uwb_rsv_has_two_drp_ies(rsv)) {
                mv = &rsv->mv;
                if (bitmap_intersects(rsv->mas.bm, conflicting_mas->bm,
                                                                UWB_NUM_MAS)) {
                        handle_conflict_expanding(drp_ie,
                                                drp_evt->beacon_slot_number,
                                                rsv, false, conflicting_mas);
                } else {
                        if (bitmap_intersects(mv->companion_mas.bm,
                                        conflicting_mas->bm, UWB_NUM_MAS)) {
                                handle_conflict_expanding(
                                        drp_ie, drp_evt->beacon_slot_number,
                                        rsv, true, conflicting_mas);
                        }
                }
        } else if (bitmap_intersects(rsv->mas.bm, conflicting_mas->bm,
                                                        UWB_NUM_MAS)) {
                handle_conflict_normal(drp_ie, drp_evt->beacon_slot_number,
                                        rsv, conflicting_mas);
        }
}

static void uwb_drp_handle_all_conflict_rsv(struct uwb_rc *rc,
                                            struct uwb_rc_evt_drp *drp_evt,
                                            struct uwb_ie_drp *drp_ie,
                                            struct uwb_mas_bm *conflicting_mas)
{
        struct uwb_rsv *rsv;

        list_for_each_entry(rsv, &rc->reservations, rc_node) {
                uwb_drp_handle_conflict_rsv(rc, rsv, drp_evt, drp_ie,
                                                        conflicting_mas);
        }
}

static void uwb_drp_process_target_accepted(struct uwb_rc *rc,
        struct uwb_rsv *rsv, struct uwb_rc_evt_drp *drp_evt,
        struct uwb_ie_drp *drp_ie, struct uwb_mas_bm *mas)
{
        struct uwb_rsv_move *mv = &rsv->mv;
        int status;

        status = uwb_ie_drp_status(drp_ie);

        if (rsv->state == UWB_RSV_STATE_T_CONFLICT) {
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
                return;
        }

        if (rsv->state == UWB_RSV_STATE_T_EXPANDING_ACCEPTED) {
                /* drp_ie is companion */
                if (!bitmap_equal(rsv->mas.bm, mas->bm, UWB_NUM_MAS)) {
                        /* stroke companion */
                        uwb_rsv_set_state(rsv,
                                UWB_RSV_STATE_T_EXPANDING_ACCEPTED);
                }
        } else {
                if (!bitmap_equal(rsv->mas.bm, mas->bm, UWB_NUM_MAS)) {
                        if (uwb_drp_avail_reserve_pending(rc, mas) == -EBUSY) {
                                /* FIXME: there is a conflict, find
                                 * the conflicting reservations and
                                 * take a sensible action. Consider
                                 * that in drp_ie there is the
                                 * "neighbour" */
                                uwb_drp_handle_all_conflict_rsv(rc, drp_evt,
                                                drp_ie, mas);
                        } else {
                                /* accept the extra reservation */
                                bitmap_copy(mv->companion_mas.bm, mas->bm,
                                                                UWB_NUM_MAS);
                                uwb_rsv_set_state(rsv,
                                        UWB_RSV_STATE_T_EXPANDING_ACCEPTED);
                        }
                } else {
                        if (status) {
                                uwb_rsv_set_state(rsv,
                                                UWB_RSV_STATE_T_ACCEPTED);
                        }
                }

        }
}

/*
 * Based on the DRP IE, transition a target reservation to a new
 * state.
 */
static void uwb_drp_process_target(struct uwb_rc *rc, struct uwb_rsv *rsv,
                   struct uwb_ie_drp *drp_ie, struct uwb_rc_evt_drp *drp_evt)
{
        struct device *dev = &rc->uwb_dev.dev;
        struct uwb_rsv_move *mv = &rsv->mv;
        int status;
        enum uwb_drp_reason reason_code;
        struct uwb_mas_bm mas;

        status = uwb_ie_drp_status(drp_ie);
        reason_code = uwb_ie_drp_reason_code(drp_ie);
        uwb_drp_ie_to_bm(&mas, drp_ie);

        switch (reason_code) {
        case UWB_DRP_REASON_ACCEPTED:
                uwb_drp_process_target_accepted(rc, rsv, drp_evt, drp_ie, &mas);
                break;

        case UWB_DRP_REASON_MODIFIED:
                /* check to see if we have already modified the reservation */
                if (bitmap_equal(rsv->mas.bm, mas.bm, UWB_NUM_MAS)) {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
                        break;
                }

                /* find if the owner wants to expand or reduce */
                if (bitmap_subset(mas.bm, rsv->mas.bm, UWB_NUM_MAS)) {
                        /* owner is reducing */
                        bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm, mas.bm,
                                UWB_NUM_MAS);
                        uwb_drp_avail_release(rsv->rc, &mv->companion_mas);
                }

                bitmap_copy(rsv->mas.bm, mas.bm, UWB_NUM_MAS);
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_RESIZED);
                break;
        default:
                dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
                         reason_code, status);
        }
}

static void uwb_drp_process_owner_accepted(struct uwb_rsv *rsv,
                                                struct uwb_mas_bm *mas)
{
        struct uwb_rsv_move *mv = &rsv->mv;

        switch (rsv->state) {
        case UWB_RSV_STATE_O_PENDING:
        case UWB_RSV_STATE_O_INITIATED:
        case UWB_RSV_STATE_O_ESTABLISHED:
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                break;
        case UWB_RSV_STATE_O_MODIFIED:
                if (bitmap_equal(mas->bm, rsv->mas.bm, UWB_NUM_MAS))
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                else
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);
                break;

        case UWB_RSV_STATE_O_MOVE_REDUCING: /* shouldn' t be a problem */
                if (bitmap_equal(mas->bm, rsv->mas.bm, UWB_NUM_MAS))
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
                else
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
                break;
        case UWB_RSV_STATE_O_MOVE_EXPANDING:
                if (bitmap_equal(mas->bm, mv->companion_mas.bm, UWB_NUM_MAS)) {
                        /* Companion reservation accepted */
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
                } else {
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
                }
                break;
        case UWB_RSV_STATE_O_MOVE_COMBINING:
                if (bitmap_equal(mas->bm, rsv->mas.bm, UWB_NUM_MAS))
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
                else
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
                break;
        default:
                break;
        }
}
/*
 * Based on the DRP IE, transition an owner reservation to a new
 * state.
 */
static void uwb_drp_process_owner(struct uwb_rc *rc, struct uwb_rsv *rsv,
                                  struct uwb_dev *src, struct uwb_ie_drp *drp_ie,
                                  struct uwb_rc_evt_drp *drp_evt)
{
        struct device *dev = &rc->uwb_dev.dev;
        int status;
        enum uwb_drp_reason reason_code;
        struct uwb_mas_bm mas;

        status = uwb_ie_drp_status(drp_ie);
        reason_code = uwb_ie_drp_reason_code(drp_ie);
        uwb_drp_ie_to_bm(&mas, drp_ie);

        if (status) {
                switch (reason_code) {
                case UWB_DRP_REASON_ACCEPTED:
                        uwb_drp_process_owner_accepted(rsv, &mas);
                        break;
                default:
                        dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
                                 reason_code, status);
                }
        } else {
                switch (reason_code) {
                case UWB_DRP_REASON_PENDING:
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_PENDING);
                        break;
                case UWB_DRP_REASON_DENIED:
                        uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
                        break;
                case UWB_DRP_REASON_CONFLICT:
                        /* resolve the conflict */
                        bitmap_complement(mas.bm, src->last_availability_bm,
                                          UWB_NUM_MAS);
                        uwb_drp_handle_conflict_rsv(rc, rsv, drp_evt, drp_ie, &mas);
                        break;
                default:
                        dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
                                 reason_code, status);
                }
        }
}

static void uwb_cnflt_alien_stroke_timer(struct uwb_cnflt_alien *cnflt)
{
        unsigned timeout_us = UWB_MAX_LOST_BEACONS * UWB_SUPERFRAME_LENGTH_US;
        mod_timer(&cnflt->timer, jiffies + usecs_to_jiffies(timeout_us));
}

static void uwb_cnflt_update_work(struct work_struct *work)
{
        struct uwb_cnflt_alien *cnflt = container_of(work,
                                                     struct uwb_cnflt_alien,
                                                     cnflt_update_work);
        struct uwb_cnflt_alien *c;
        struct uwb_rc *rc = cnflt->rc;

        unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;

        mutex_lock(&rc->rsvs_mutex);

        list_del(&cnflt->rc_node);

        /* update rc global conflicting alien bitmap */
        bitmap_zero(rc->cnflt_alien_bitmap.bm, UWB_NUM_MAS);

        list_for_each_entry(c, &rc->cnflt_alien_list, rc_node) {
                bitmap_or(rc->cnflt_alien_bitmap.bm, rc->cnflt_alien_bitmap.bm,
                                                c->mas.bm, UWB_NUM_MAS);
        }

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

        kfree(cnflt);
        mutex_unlock(&rc->rsvs_mutex);
}

static void uwb_cnflt_timer(struct timer_list *t)
{
        struct uwb_cnflt_alien *cnflt = from_timer(cnflt, t, timer);

        queue_work(cnflt->rc->rsv_workq, &cnflt->cnflt_update_work);
}

/*
 * We have received an DRP_IE of type Alien BP and we need to make
 * sure we do not transmit in conflicting MASs.
 */
static void uwb_drp_handle_alien_drp(struct uwb_rc *rc, struct uwb_ie_drp *drp_ie)
{
        struct device *dev = &rc->uwb_dev.dev;
        struct uwb_mas_bm mas;
        struct uwb_cnflt_alien *cnflt;
        unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;

        uwb_drp_ie_to_bm(&mas, drp_ie);

        list_for_each_entry(cnflt, &rc->cnflt_alien_list, rc_node) {
                if (bitmap_equal(cnflt->mas.bm, mas.bm, UWB_NUM_MAS)) {
                        /* Existing alien BP reservation conflicting
                         * bitmap, just reset the timer */
                        uwb_cnflt_alien_stroke_timer(cnflt);
                        return;
                }
        }

        /* New alien BP reservation conflicting bitmap */

        /* alloc and initialize new uwb_cnflt_alien */
        cnflt = kzalloc(sizeof(struct uwb_cnflt_alien), GFP_KERNEL);
        if (!cnflt) {
                dev_err(dev, "failed to alloc uwb_cnflt_alien struct\n");
                return;
        }

        INIT_LIST_HEAD(&cnflt->rc_node);
        timer_setup(&cnflt->timer, uwb_cnflt_timer, 0);

        cnflt->rc = rc;
        INIT_WORK(&cnflt->cnflt_update_work, uwb_cnflt_update_work);

        bitmap_copy(cnflt->mas.bm, mas.bm, UWB_NUM_MAS);

        list_add_tail(&cnflt->rc_node, &rc->cnflt_alien_list);

        /* update rc global conflicting alien bitmap */
        bitmap_or(rc->cnflt_alien_bitmap.bm, rc->cnflt_alien_bitmap.bm, mas.bm, UWB_NUM_MAS);

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

        /* start the timer */
        uwb_cnflt_alien_stroke_timer(cnflt);
}

static void uwb_drp_process_not_involved(struct uwb_rc *rc,
                                         struct uwb_rc_evt_drp *drp_evt,
                                         struct uwb_ie_drp *drp_ie)
{
        struct uwb_mas_bm mas;

        uwb_drp_ie_to_bm(&mas, drp_ie);
        uwb_drp_handle_all_conflict_rsv(rc, drp_evt, drp_ie, &mas);
}

static void uwb_drp_process_involved(struct uwb_rc *rc, struct uwb_dev *src,
                                     struct uwb_rc_evt_drp *drp_evt,
                                     struct uwb_ie_drp *drp_ie)
{
        struct uwb_rsv *rsv;

        rsv = uwb_rsv_find(rc, src, drp_ie);
        if (!rsv) {
                /*
                 * No reservation? It's either for a recently
                 * terminated reservation; or the DRP IE couldn't be
                 * processed (e.g., an invalid IE or out of memory).
                 */
                return;
        }

        /*
         * Do nothing with DRP IEs for reservations that have been
         * terminated.
         */
        if (rsv->state == UWB_RSV_STATE_NONE) {
                uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
                return;
        }

        if (uwb_ie_drp_owner(drp_ie))
                uwb_drp_process_target(rc, rsv, drp_ie, drp_evt);
        else
                uwb_drp_process_owner(rc, rsv, src, drp_ie, drp_evt);

}


static bool uwb_drp_involves_us(struct uwb_rc *rc, struct uwb_ie_drp *drp_ie)
{
        return uwb_dev_addr_cmp(&rc->uwb_dev.dev_addr, &drp_ie->dev_addr) == 0;
}

/*
 * Process a received DRP IE.
 */
static void uwb_drp_process(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
                            struct uwb_dev *src, struct uwb_ie_drp *drp_ie)
{
        if (uwb_ie_drp_type(drp_ie) == UWB_DRP_TYPE_ALIEN_BP)
                uwb_drp_handle_alien_drp(rc, drp_ie);
        else if (uwb_drp_involves_us(rc, drp_ie))
                uwb_drp_process_involved(rc, src, drp_evt, drp_ie);
        else
                uwb_drp_process_not_involved(rc, drp_evt, drp_ie);
}

/*
 * Process a received DRP Availability IE
 */
static void uwb_drp_availability_process(struct uwb_rc *rc, struct uwb_dev *src,
                                         struct uwb_ie_drp_avail *drp_availability_ie)
{
        bitmap_copy(src->last_availability_bm,
                    drp_availability_ie->bmp, UWB_NUM_MAS);
}

/*
 * Process all the DRP IEs (both DRP IEs and the DRP Availability IE)
 * from a device.
 */
static
void uwb_drp_process_all(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
                         size_t ielen, struct uwb_dev *src_dev)
{
        struct device *dev = &rc->uwb_dev.dev;
        struct uwb_ie_hdr *ie_hdr;
        void *ptr;

        ptr = drp_evt->ie_data;
        for (;;) {
                ie_hdr = uwb_ie_next(&ptr, &ielen);
                if (!ie_hdr)
                        break;

                switch (ie_hdr->element_id) {
                case UWB_IE_DRP_AVAILABILITY:
                        uwb_drp_availability_process(rc, src_dev, (struct uwb_ie_drp_avail *)ie_hdr);
                        break;
                case UWB_IE_DRP:
                        uwb_drp_process(rc, drp_evt, src_dev, (struct uwb_ie_drp *)ie_hdr);
                        break;
                default:
                        dev_warn(dev, "unexpected IE in DRP notification\n");
                        break;
                }
        }

        if (ielen > 0)
                dev_warn(dev, "%d octets remaining in DRP notification\n",
                         (int)ielen);
}

/**
 * uwbd_evt_handle_rc_drp - handle a DRP_IE event
 * @evt: the DRP_IE event from the radio controller
 *
 * This processes DRP notifications from the radio controller, either
 * initiating a new reservation or transitioning an existing
 * reservation into a different state.
 *
 * DRP notifications can occur for three different reasons:
 *
 * - UWB_DRP_NOTIF_DRP_IE_RECVD: one or more DRP IEs with the RC as
 *   the target or source have been received.
 *
 *   These DRP IEs could be new or for an existing reservation.
 *
 *   If the DRP IE for an existing reservation ceases to be to
 *   received for at least mMaxLostBeacons, the reservation should be
 *   considered to be terminated.  Note that the TERMINATE reason (see
 *   below) may not always be signalled (e.g., the remote device has
 *   two or more reservations established with the RC).
 *
 * - UWB_DRP_NOTIF_CONFLICT: DRP IEs from any device in the beacon
 *   group conflict with the RC's reservations.
 *
 * - UWB_DRP_NOTIF_TERMINATE: DRP IEs are no longer being received
 *   from a device (i.e., it's terminated all reservations).
 *
 * Only the software state of the reservations is changed; the setting
 * of the radio controller's DRP IEs is done after all the events in
 * an event buffer are processed.  This saves waiting multiple times
 * for the SET_DRP_IE command to complete.
 */
int uwbd_evt_handle_rc_drp(struct uwb_event *evt)
{
        struct device *dev = &evt->rc->uwb_dev.dev;
        struct uwb_rc *rc = evt->rc;
        struct uwb_rc_evt_drp *drp_evt;
        size_t ielength, bytes_left;
        struct uwb_dev_addr src_addr;
        struct uwb_dev *src_dev;

        /* Is there enough data to decode the event (and any IEs in
           its payload)? */
        if (evt->notif.size < sizeof(*drp_evt)) {
                dev_err(dev, "DRP event: Not enough data to decode event "
                        "[%zu bytes left, %zu needed]\n",
                        evt->notif.size, sizeof(*drp_evt));
                return 0;
        }
        bytes_left = evt->notif.size - sizeof(*drp_evt);
        drp_evt = container_of(evt->notif.rceb, struct uwb_rc_evt_drp, rceb);
        ielength = le16_to_cpu(drp_evt->ie_length);
        if (bytes_left != ielength) {
                dev_err(dev, "DRP event: Not enough data in payload [%zu"
                        "bytes left, %zu declared in the event]\n",
                        bytes_left, ielength);
                return 0;
        }

        memcpy(src_addr.data, &drp_evt->src_addr, sizeof(src_addr));
        src_dev = uwb_dev_get_by_devaddr(rc, &src_addr);
        if (!src_dev) {
                /*
                 * A DRP notification from an unrecognized device.
                 *
                 * This is probably from a WUSB device that doesn't
                 * have an EUI-48 and therefore doesn't show up in the
                 * UWB device database.  It's safe to simply ignore
                 * these.
                 */
                return 0;
        }

        mutex_lock(&rc->rsvs_mutex);

        /* We do not distinguish from the reason */
        uwb_drp_process_all(rc, drp_evt, ielength, src_dev);

        mutex_unlock(&rc->rsvs_mutex);

        uwb_dev_put(src_dev);
        return 0;
}