/*
   * 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.
   *
   * 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/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)
  ",
  				uwb_rc_strerror(r->bResultCode), r->bResultCode);
  	} else
  		dev_err(&rc->uwb_dev.dev, "SET-DRP-IE: timeout
  ");

  	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)
  ",
  			 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)
  ",
  				 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)
  ",
  				 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(unsigned long arg)
  {
  	struct uwb_cnflt_alien *cnflt = (struct uwb_cnflt_alien *)arg;
  
  	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
  ");

  		return;
  	}

  	INIT_LIST_HEAD(&cnflt->rc_node);

  	setup_timer(&cnflt->timer, uwb_cnflt_timer, (unsigned long)cnflt);

  
  	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
  ");
  			break;
  		}
  	}
  
  	if (ielen > 0)
  		dev_warn(dev, "%d octets remaining in DRP notification
  ",
  			 (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]
  ",
  			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]
  ",
  			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;
  }