kernel / drivers / 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 <[e-mail]>
 * 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;
}