drivers/uwb/drp.c - maze/linux - Git at Google

 /*
  * 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/delay.h>
 #include "uwb-internal.h"

 /**
  * 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->uwb_dev.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.
  */
 static
 int uwb_rc_gen_send_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;
 	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;
 	}
 	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];

 	/* 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;
 		}
 	}
 	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:
 	kfree(cmd);
 error:
 	return result;

 }
 /**
  * Send all DRP IEs associated with this host
  *
  * @returns:    >= 0 number of bytes still available in the beacon
  *              < 0 errno code on error.
  *
  * As per the protocol we obtain the host controller device lock to access
  * bandwidth structures.
  */
 int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
 {
 	int result;

 	mutex_lock(&rc->uwb_dev.mutex);
 	result = uwb_rc_gen_send_drp_ie(rc);
 	mutex_unlock(&rc->uwb_dev.mutex);
 	return result;
 }

 void uwb_drp_handle_timeout(struct uwb_rsv *rsv)
 {
 	struct device *dev = &rsv->rc->uwb_dev.dev;

 	dev_dbg(dev, "reservation timeout in state %s (%d)\n",
 		uwb_rsv_state_str(rsv->state), rsv->state);

 	switch (rsv->state) {
 	case UWB_RSV_STATE_O_INITIATED:
 		if (rsv->is_multicast) {
 			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
 			return;
 		}
 		break;
 	case UWB_RSV_STATE_O_ESTABLISHED:
 		if (rsv->is_multicast)
 			return;
 		break;
 	default:
 		break;
 	}
 	uwb_rsv_remove(rsv);
 }

 /*
  * 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 device *dev = &rc->uwb_dev.dev;
 	int status;
 	enum uwb_drp_reason reason_code;

 	status = uwb_ie_drp_status(drp_ie);
 	reason_code = uwb_ie_drp_reason_code(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);
 			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);
 			break;
 		default:
 			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
 				 reason_code, status);
 		}
 	}
 }

 /*
  * 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_ie_drp *drp_ie)
 {
 	struct device *dev = &rc->uwb_dev.dev;
 	int status;
 	enum uwb_drp_reason reason_code;

 	status = uwb_ie_drp_status(drp_ie);
 	reason_code = uwb_ie_drp_reason_code(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);
 			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:
 		case UWB_DRP_REASON_MODIFIED:
 			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
 				reason_code, status);
 			break;
 		default:
 			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
 				 reason_code, status);
 		}
 	}
 }

 /*
  * 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).
  */
 static void uwb_drp_process(struct uwb_rc *rc, struct uwb_dev *src,
 		     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);
 	else
 		uwb_drp_process_owner(rc, rsv, drp_ie);
 }


 /*
  * 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:
 			/* FIXME: does something need to be done with this? */
 			break;
 		case UWB_IE_DRP:
 			uwb_drp_process(rc, 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);
 }


 /*
  * 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
  *
  * 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 recieved.
  *
  *   These DRP IEs could be new or for an existing reservation.
  *
  *   If the DRP IE for an existing reservation ceases to be to
  *   recieved 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;
 	int reason;

 	/* 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);

 	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;
 	}

 	mutex_unlock(&rc->rsvs_mutex);

 	uwb_dev_put(src_dev);
 	return 0;
 }
	/*
	* 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/delay.h>
	#include "uwb-internal.h"

	/**
	* 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->uwb_dev.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.
	*/
	static
	int uwb_rc_gen_send_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;
	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;
	}
	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];

	/* 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;
	}
	}
	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:
	kfree(cmd);
	error:
	return result;

	}
	/**
	* Send all DRP IEs associated with this host
	*
	* @returns: >= 0 number of bytes still available in the beacon
	* < 0 errno code on error.
	*
	* As per the protocol we obtain the host controller device lock to access
	* bandwidth structures.
	*/
	int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
	{
	int result;

	mutex_lock(&rc->uwb_dev.mutex);
	result = uwb_rc_gen_send_drp_ie(rc);
	mutex_unlock(&rc->uwb_dev.mutex);
	return result;
	}

	void uwb_drp_handle_timeout(struct uwb_rsv *rsv)
	{
	struct device *dev = &rsv->rc->uwb_dev.dev;

	dev_dbg(dev, "reservation timeout in state %s (%d)\n",
	uwb_rsv_state_str(rsv->state), rsv->state);

	switch (rsv->state) {
	case UWB_RSV_STATE_O_INITIATED:
	if (rsv->is_multicast) {
	uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
	return;
	}
	break;
	case UWB_RSV_STATE_O_ESTABLISHED:
	if (rsv->is_multicast)
	return;
	break;
	default:
	break;
	}
	uwb_rsv_remove(rsv);
	}

	/*
	* 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 device *dev = &rc->uwb_dev.dev;
	int status;
	enum uwb_drp_reason reason_code;

	status = uwb_ie_drp_status(drp_ie);
	reason_code = uwb_ie_drp_reason_code(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);
	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);
	break;
	default:
	dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
	reason_code, status);
	}
	}
	}

	/*
	* 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_ie_drp *drp_ie)
	{
	struct device *dev = &rc->uwb_dev.dev;
	int status;
	enum uwb_drp_reason reason_code;

	status = uwb_ie_drp_status(drp_ie);
	reason_code = uwb_ie_drp_reason_code(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);
	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:
	case UWB_DRP_REASON_MODIFIED:
	dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
	reason_code, status);
	break;
	default:
	dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
	reason_code, status);
	}
	}
	}

	/*
	* 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).
	*/
	static void uwb_drp_process(struct uwb_rc rc, struct uwb_dev src,
	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);
	else
	uwb_drp_process_owner(rc, rsv, drp_ie);
	}


	/*
	* 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:
	/* FIXME: does something need to be done with this? */
	break;
	case UWB_IE_DRP:
	uwb_drp_process(rc, 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);
	}


	/*
	* 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
	*
	* 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 recieved.
	*
	* These DRP IEs could be new or for an existing reservation.
	*
	* If the DRP IE for an existing reservation ceases to be to
	* recieved 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;
	int reason;

	/* 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);

	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;
	}

	mutex_unlock(&rc->rsvs_mutex);

	uwb_dev_put(src_dev);
	return 0;
	}