uwb: improved MAS allocator and reservation conflict handling

Greatly enhance the MAS allocator:
  - Handle row and column reservations.
  - Permit all the available MAS to be allocated.
  - Follows the WiMedia rules on MAS selection.

Take appropriate action when reservation conflicts are detected.
  - Correctly identify which reservation wins the conflict.
  - Protect alien BP reservations.
  - If an owned reservation loses, resize/move it.
  - Follow the backoff procedure before requesting additional MAS.

When reservations are terminated, move the remaining reservations (if
necessary) so they keep following the MAS allocation rules.

Signed-off-by: Stefano Panella <stefano.panella@csr.com>
Signed-off-by: David Vrabel <david.vrabel@csr.com>

1 files changed, 527 insertions, 154 deletions

diff --git a/drivers/uwb/drp.c b/drivers/uwb/drp.c
index fe32814..2b4f940 100644
--- a/drivers/uwb/drp.c
+++ b/drivers/uwb/drp.c
@@ -23,6 +23,59 @@
 #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 mantained, 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;
+
+	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(&rc->rsvs_lock);
+	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(&rc->rsvs_lock);
+}
+
 /**
  * Construct and send the SET DRP IE
  *
@@ -46,18 +99,23 @@
 int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
 {
 	int result;
-	struct device *dev = &rc->uwb_dev.dev;
 	struct uwb_rc_cmd_set_drp_ie *cmd;
-	struct uwb_rc_evt_set_drp_ie reply;
 	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)
+		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);
@@ -68,109 +126,322 @@ int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
 	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;	
+			}
 		}
 	}
-	memcpy(IEDataptr, &rc->drp_avail.ie, sizeof(rc->drp_avail.ie));
 
-	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
-	reply.rceb.wEvent = UWB_RC_CMD_SET_DRP_IE;
-	result = uwb_rc_cmd(rc, "SET-DRP-IE", &cmd->rccb,
-			sizeof(*cmd) + num_bytes, &reply.rceb,
-			sizeof(reply));
-	if (result < 0)
-		goto error_cmd;
-	result = le16_to_cpu(reply.wRemainingSpace);
-	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
-		dev_err(&rc->uwb_dev.dev, "SET-DRP-IE: command execution "
-				"failed: %s (%d). RemainingSpace in beacon "
-				"= %d\n", uwb_rc_strerror(reply.bResultCode),
-				reply.bResultCode, result);
-		result = -EIO;
-	} else {
-		dev_dbg(dev, "SET-DRP-IE sent. RemainingSpace in beacon "
-			     "= %d.\n", result);
-		result = 0;
-	}
-error_cmd:
+	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;
 }
 
-void uwb_drp_handle_timeout(struct uwb_rsv *rsv)
+/*
+ * 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)
 {
-	struct device *dev = &rsv->rc->uwb_dev.dev;
+	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;
+	}
 
-	dev_dbg(dev, "reservation timeout in state %s (%d)\n",
-		uwb_rsv_state_str(rsv->state), rsv->state);
+	/* [ECMA-368 2nd Edition] 17.4.6-4 */
+	if (our_status == 1 && ext_status == 0) {
+		return UWB_DRP_CONFLICT_MANTAIN;
+	}
 
-	switch (rsv->state) {
-	case UWB_RSV_STATE_O_INITIATED:
-		if (rsv->is_multicast) {
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
-			return;
+	/* [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;
+			}
 		}
-		break;
-	case UWB_RSV_STATE_O_ESTABLISHED:
-		if (rsv->is_multicast)
-			return;
-		break;
-	default:
-		break;
+	} 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);
 	}
-	uwb_rsv_remove(rsv);
 }
 
+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);	
+	}
+}
+	
 /*
  * 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_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);
 
-	if (status) {
-		switch (reason_code) {
-		case UWB_DRP_REASON_ACCEPTED:
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
-			break;
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+	switch (reason_code) {
+	case UWB_DRP_REASON_ACCEPTED:
+
+		if (rsv->state == UWB_RSV_STATE_T_CONFLICT) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
 			break;
-		default:
-			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
-				 reason_code, status);
 		}
-	} else {
-		switch (reason_code) {
-		case UWB_DRP_REASON_ACCEPTED:
-			/* New reservations are handled in uwb_rsv_find(). */
-			break;
-		case UWB_DRP_REASON_DENIED:
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
-			break;
-		case UWB_DRP_REASON_CONFLICT:
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+
+		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);
+				}
+			}
+			
+		}
+		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;
-		default:
-			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
-				 reason_code, status);
 		}
+
+		/* 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);
 	}
 }
 
@@ -179,23 +450,60 @@ static void uwb_drp_process_target(struct uwb_rc *rc, struct uwb_rsv *rsv,
  * state.
  */
 static void uwb_drp_process_owner(struct uwb_rc *rc, struct uwb_rsv *rsv,
-				  struct uwb_ie_drp *drp_ie)
+				  struct uwb_dev *src, 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);
 
 	if (status) {
 		switch (reason_code) {
 		case UWB_DRP_REASON_ACCEPTED:
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
-			break;
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+			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;	
+			}
 			break;
 		default:
 			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
@@ -210,9 +518,10 @@ static void uwb_drp_process_owner(struct uwb_rc *rc, struct uwb_rsv *rsv,
 			uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
 			break;
 		case UWB_DRP_REASON_CONFLICT:
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+			/* 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",
@@ -221,12 +530,110 @@ static void uwb_drp_process_owner(struct uwb_rc *rc, struct uwb_rsv *rsv,
 	}
 }
 
+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);
+}
+
 /*
- * Process a received DRP IE, it's either for a reservation owned by
- * the RC or targeted at it (or it's for a WUSB cluster reservation).
+ * 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_process(struct uwb_rc *rc, struct uwb_dev *src,
-		     struct uwb_ie_drp *drp_ie)
+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;
+	char buf[72];
+	unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;
+	
+	uwb_drp_ie_to_bm(&mas, drp_ie);
+	bitmap_scnprintf(buf, sizeof(buf), mas.bm, UWB_NUM_MAS);
+	
+	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");
+	INIT_LIST_HEAD(&cnflt->rc_node);
+	init_timer(&cnflt->timer);
+	cnflt->timer.function = uwb_cnflt_timer;
+	cnflt->timer.data     = (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;
 
@@ -239,7 +646,7 @@ static void uwb_drp_process(struct uwb_rc *rc, struct uwb_dev *src,
 		 */
 		return;
 	}
-
+	
 	/*
 	 * Do nothing with DRP IEs for reservations that have been
 	 * terminated.
@@ -248,13 +655,43 @@ static void uwb_drp_process(struct uwb_rc *rc, struct uwb_dev *src,
 		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);
+		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_owner(rc, rsv, drp_ie);
+		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)
@@ -276,10 +713,10 @@ void uwb_drp_process_all(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
 
 		switch (ie_hdr->element_id) {
 		case UWB_IE_DRP_AVAILABILITY:
-			/* FIXME: does something need to be done with this? */
+			uwb_drp_availability_process(rc, src_dev, (struct uwb_ie_drp_avail *)ie_hdr);
 			break;
 		case UWB_IE_DRP:
-			uwb_drp_process(rc, src_dev, (struct uwb_ie_drp *)ie_hdr);
+			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");
@@ -292,55 +729,6 @@ void uwb_drp_process_all(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
 			 (int)ielen);
 }
 
-
-/*
- * Go through all the DRP IEs and find the ones that conflict with our
- * reservations.
- *
- * FIXME: must resolve the conflict according the the rules in
- * [ECMA-368].
- */
-static
-void uwb_drp_process_conflict_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;
-	struct uwb_ie_drp *drp_ie;
-	void *ptr;
-
-	ptr = drp_evt->ie_data;
-	for (;;) {
-		ie_hdr = uwb_ie_next(&ptr, &ielen);
-		if (!ie_hdr)
-			break;
-
-		drp_ie = container_of(ie_hdr, struct uwb_ie_drp, hdr);
-
-		/* FIXME: check if this DRP IE conflicts. */
-	}
-
-	if (ielen > 0)
-		dev_warn(dev, "%d octets remaining in DRP notification\n",
-			 (int)ielen);
-}
-
-
-/*
- * Terminate all reservations owned by, or targeted at, 'uwb_dev'.
- */
-static void uwb_drp_terminate_all(struct uwb_rc *rc, struct uwb_dev *uwb_dev)
-{
-	struct uwb_rsv *rsv;
-
-	list_for_each_entry(rsv, &rc->reservations, rc_node) {
-		if (rsv->owner == uwb_dev
-		    || (rsv->target.type == UWB_RSV_TARGET_DEV && rsv->target.dev == uwb_dev))
-			uwb_rsv_remove(rsv);
-	}
-}
-
-
 /**
  * uwbd_evt_handle_rc_drp - handle a DRP_IE event
  * @evt: the DRP_IE event from the radio controller
@@ -381,7 +769,6 @@ int uwbd_evt_handle_rc_drp(struct uwb_event *evt)
 	size_t ielength, bytes_left;
 	struct uwb_dev_addr src_addr;
 	struct uwb_dev *src_dev;
-	int reason;
 
 	/* Is there enough data to decode the event (and any IEs in
 	   its payload)? */
@@ -417,22 +804,8 @@ int uwbd_evt_handle_rc_drp(struct uwb_event *evt)
 
 	mutex_lock(&rc->rsvs_mutex);
 
-	reason = uwb_rc_evt_drp_reason(drp_evt);
-
-	switch (reason) {
-	case UWB_DRP_NOTIF_DRP_IE_RCVD:
-		uwb_drp_process_all(rc, drp_evt, ielength, src_dev);
-		break;
-	case UWB_DRP_NOTIF_CONFLICT:
-		uwb_drp_process_conflict_all(rc, drp_evt, ielength, src_dev);
-		break;
-	case UWB_DRP_NOTIF_TERMINATE:
-		uwb_drp_terminate_all(rc, src_dev);
-		break;
-	default:
-		dev_warn(dev, "ignored DRP event with reason code: %d\n", reason);
-		break;
-	}
+	/* We do not distinguish from the reason */
+	uwb_drp_process_all(rc, drp_evt, ielength, src_dev);
 
 	mutex_unlock(&rc->rsvs_mutex);