/*
   * Ultra Wide Band
   * Beacon management
   *
   * Copyright (C) 2005-2006 Intel Corporation
   * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
   *
   * 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, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   *
   *
   * FIXME: docs
   */
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/kdev_t.h>
  #include <linux/slab.h>
  
  #include "uwb-internal.h"
  
  /* Start Beaconing command structure */
  struct uwb_rc_cmd_start_beacon {
  	struct uwb_rccb rccb;
  	__le16 wBPSTOffset;
  	u8 bChannelNumber;
  } __attribute__((packed));
  
  
  static int uwb_rc_start_beacon(struct uwb_rc *rc, u16 bpst_offset, u8 channel)
  {
  	int result;
  	struct uwb_rc_cmd_start_beacon *cmd;
  	struct uwb_rc_evt_confirm reply;
  
  	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
  	if (cmd == NULL)
  		return -ENOMEM;
  	cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
  	cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_START_BEACON);
  	cmd->wBPSTOffset = cpu_to_le16(bpst_offset);
  	cmd->bChannelNumber = channel;
  	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
  	reply.rceb.wEvent = UWB_RC_CMD_START_BEACON;
  	result = uwb_rc_cmd(rc, "START-BEACON", &cmd->rccb, sizeof(*cmd),
  			    &reply.rceb, sizeof(reply));
  	if (result < 0)
  		goto error_cmd;
  	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
  		dev_err(&rc->uwb_dev.dev,
  			"START-BEACON: command execution failed: %s (%d)
  ",
  			uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
  		result = -EIO;
  	}
  error_cmd:
  	kfree(cmd);
  	return result;
  }
  
  static int uwb_rc_stop_beacon(struct uwb_rc *rc)
  {
  	int result;
  	struct uwb_rccb *cmd;
  	struct uwb_rc_evt_confirm reply;
  
  	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
  	if (cmd == NULL)
  		return -ENOMEM;
  	cmd->bCommandType = UWB_RC_CET_GENERAL;
  	cmd->wCommand = cpu_to_le16(UWB_RC_CMD_STOP_BEACON);
  	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
  	reply.rceb.wEvent = UWB_RC_CMD_STOP_BEACON;
  	result = uwb_rc_cmd(rc, "STOP-BEACON", cmd, sizeof(*cmd),
  			    &reply.rceb, sizeof(reply));
  	if (result < 0)
  		goto error_cmd;
  	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
  		dev_err(&rc->uwb_dev.dev,
  			"STOP-BEACON: command execution failed: %s (%d)
  ",
  			uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
  		result = -EIO;
  	}
  error_cmd:
  	kfree(cmd);
  	return result;
  }
  
  /*
   * Start/stop beacons
   *
   * @rc:          UWB Radio Controller to operate on
   * @channel:     UWB channel on which to beacon (WUSB[table
   *               5-12]). If -1, stop beaconing.
   * @bpst_offset: Beacon Period Start Time offset; FIXME-do zero
   *
   * According to WHCI 0.95 [4.13.6] the driver will only receive the RCEB
   * of a SET IE command after the device sent the first beacon that includes
   * the IEs specified in the SET IE command. So, after we start beaconing we
   * check if there is anything in the IE cache and call the SET IE command
   * if needed.
   */
  int uwb_rc_beacon(struct uwb_rc *rc, int channel, unsigned bpst_offset)
  {
  	int result;
  	struct device *dev = &rc->uwb_dev.dev;
  
  	dev_dbg(dev, "%s: channel = %d
  ", __func__, channel);
  	if (channel < 0)
  		channel = -1;
  	if (channel == -1)
  		result = uwb_rc_stop_beacon(rc);
  	else {
  		/* channel >= 0...dah */
  		result = uwb_rc_start_beacon(rc, bpst_offset, channel);
  		if (result < 0)
  			return result;
  		if (le16_to_cpu(rc->ies->wIELength) > 0) {
  			result = uwb_rc_set_ie(rc, rc->ies);
  			if (result < 0) {
  				dev_err(dev, "Cannot set new IE on device: "
  					"%d
  ", result);
  				result = uwb_rc_stop_beacon(rc);
  				channel = -1;
  				bpst_offset = 0;
  			}
  		}
  	}
  
  	if (result >= 0)
  		rc->beaconing = channel;
  	return result;
  }
  
  /*
   * Beacon cache
   *
   * The purpose of this is to speed up the lookup of becon information
   * when a new beacon arrives. The UWB Daemon uses it also to keep a
   * tab of which devices are in radio distance and which not. When a
   * device's beacon stays present for more than a certain amount of
   * time, it is considered a new, usable device. When a beacon ceases
   * to be received for a certain amount of time, it is considered that
   * the device is gone.
   *
   * FIXME: use an allocator for the entries
   * FIXME: use something faster for search than a list
   */
  
  void uwb_bce_kfree(struct kref *_bce)
  {
  	struct uwb_beca_e *bce = container_of(_bce, struct uwb_beca_e, refcnt);
  
  	kfree(bce->be);
  	kfree(bce);
  }
  
  
  /* Find a beacon by dev addr in the cache */
  static
  struct uwb_beca_e *__uwb_beca_find_bydev(struct uwb_rc *rc,
  					 const struct uwb_dev_addr *dev_addr)
  {
  	struct uwb_beca_e *bce, *next;
  	list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
  		if (!memcmp(&bce->dev_addr, dev_addr, sizeof(bce->dev_addr)))
  			goto out;
  	}
  	bce = NULL;
  out:
  	return bce;
  }
  
  /* Find a beacon by dev addr in the cache */
  static
  struct uwb_beca_e *__uwb_beca_find_bymac(struct uwb_rc *rc,
  					 const struct uwb_mac_addr *mac_addr)
  {
  	struct uwb_beca_e *bce, *next;
  	list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
  		if (!memcmp(bce->mac_addr, mac_addr->data,
  			    sizeof(struct uwb_mac_addr)))
  			goto out;
  	}
  	bce = NULL;
  out:
  	return bce;
  }
  
  /**
   * uwb_dev_get_by_devaddr - get a UWB device with a specific DevAddr
   * @rc:      the radio controller that saw the device
   * @devaddr: DevAddr of the UWB device to find
   *
   * There may be more than one matching device (in the case of a
   * DevAddr conflict), but only the first one is returned.
   */
  struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
  				       const struct uwb_dev_addr *devaddr)
  {
  	struct uwb_dev *found = NULL;
  	struct uwb_beca_e *bce;
  
  	mutex_lock(&rc->uwb_beca.mutex);
  	bce = __uwb_beca_find_bydev(rc, devaddr);
  	if (bce)
  		found = uwb_dev_try_get(rc, bce->uwb_dev);
  	mutex_unlock(&rc->uwb_beca.mutex);
  
  	return found;
  }
  
  /**
   * uwb_dev_get_by_macaddr - get a UWB device with a specific EUI-48
   * @rc:      the radio controller that saw the device
   * @devaddr: EUI-48 of the UWB device to find
   */
  struct uwb_dev *uwb_dev_get_by_macaddr(struct uwb_rc *rc,
  				       const struct uwb_mac_addr *macaddr)
  {
  	struct uwb_dev *found = NULL;
  	struct uwb_beca_e *bce;
  
  	mutex_lock(&rc->uwb_beca.mutex);
  	bce = __uwb_beca_find_bymac(rc, macaddr);
  	if (bce)
  		found = uwb_dev_try_get(rc, bce->uwb_dev);
  	mutex_unlock(&rc->uwb_beca.mutex);
  
  	return found;
  }
  
  /* Initialize a beacon cache entry */
  static void uwb_beca_e_init(struct uwb_beca_e *bce)
  {
  	mutex_init(&bce->mutex);
  	kref_init(&bce->refcnt);
  	stats_init(&bce->lqe_stats);
  	stats_init(&bce->rssi_stats);
  }
  
  /*
   * Add a beacon to the cache
   *
   * @be:         Beacon event information
   * @bf:         Beacon frame (part of b, really)
   * @ts_jiffies: Timestamp (in jiffies) when the beacon was received
   */
  static
  struct uwb_beca_e *__uwb_beca_add(struct uwb_rc *rc,
  				  struct uwb_rc_evt_beacon *be,
  				  struct uwb_beacon_frame *bf,
  				  unsigned long ts_jiffies)
  {
  	struct uwb_beca_e *bce;
  
  	bce = kzalloc(sizeof(*bce), GFP_KERNEL);
  	if (bce == NULL)
  		return NULL;
  	uwb_beca_e_init(bce);
  	bce->ts_jiffies = ts_jiffies;
  	bce->uwb_dev = NULL;
  	list_add(&bce->node, &rc->uwb_beca.list);
  	return bce;
  }
  
  /*
   * Wipe out beacon entries that became stale
   *
   * Remove associated devicest too.
   */
  void uwb_beca_purge(struct uwb_rc *rc)
  {
  	struct uwb_beca_e *bce, *next;
  	unsigned long expires;
  
  	mutex_lock(&rc->uwb_beca.mutex);
  	list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
  		expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
  		if (time_after(jiffies, expires)) {
  			uwbd_dev_offair(bce);
  		}
  	}
  	mutex_unlock(&rc->uwb_beca.mutex);
  }
  
  /* Clean up the whole beacon cache. Called on shutdown */
  void uwb_beca_release(struct uwb_rc *rc)
  {
  	struct uwb_beca_e *bce, *next;
  
  	mutex_lock(&rc->uwb_beca.mutex);
  	list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
  		list_del(&bce->node);
  		uwb_bce_put(bce);
  	}
  	mutex_unlock(&rc->uwb_beca.mutex);
  }
  
  static void uwb_beacon_print(struct uwb_rc *rc, struct uwb_rc_evt_beacon *be,
  			     struct uwb_beacon_frame *bf)
  {
  	char macbuf[UWB_ADDR_STRSIZE];
  	char devbuf[UWB_ADDR_STRSIZE];
  	char dstbuf[UWB_ADDR_STRSIZE];
  
  	uwb_mac_addr_print(macbuf, sizeof(macbuf), &bf->Device_Identifier);
  	uwb_dev_addr_print(devbuf, sizeof(devbuf), &bf->hdr.SrcAddr);
  	uwb_dev_addr_print(dstbuf, sizeof(dstbuf), &bf->hdr.DestAddr);
  	dev_info(&rc->uwb_dev.dev,
  		 "BEACON from %s to %s (ch%u offset %u slot %u MAC %s)
  ",
  		 devbuf, dstbuf, be->bChannelNumber, be->wBPSTOffset,
  		 bf->Beacon_Slot_Number, macbuf);
  }
  
  /*
   * @bce: beacon cache entry, referenced
   */
  ssize_t uwb_bce_print_IEs(struct uwb_dev *uwb_dev, struct uwb_beca_e *bce,
  			  char *buf, size_t size)
  {
  	ssize_t result = 0;
  	struct uwb_rc_evt_beacon *be;
  	struct uwb_beacon_frame *bf;
  	int ies_len;
  	struct uwb_ie_hdr *ies;
  
  	mutex_lock(&bce->mutex);
  
  	be = bce->be;
  	if (be) {
  		bf = (struct uwb_beacon_frame *)bce->be->BeaconInfo;
  		ies_len = be->wBeaconInfoLength - sizeof(struct uwb_beacon_frame);
  		ies = (struct uwb_ie_hdr *)bf->IEData;
  
  		result = uwb_ie_dump_hex(ies, ies_len, buf, size);
  	}
  
  	mutex_unlock(&bce->mutex);
  
  	return result;
  }
  
  /*
   * Verify that the beacon event, frame and IEs are ok
   */
  static int uwb_verify_beacon(struct uwb_rc *rc, struct uwb_event *evt,
  			     struct uwb_rc_evt_beacon *be)
  {
  	int result = -EINVAL;
  	struct uwb_beacon_frame *bf;
  	struct device *dev = &rc->uwb_dev.dev;
  
  	/* Is there enough data to decode a beacon frame? */
  	if (evt->notif.size < sizeof(*be) + sizeof(*bf)) {
  		dev_err(dev, "BEACON event: Not enough data to decode "
  			"(%zu vs %zu bytes needed)
  ", evt->notif.size,
  			sizeof(*be) + sizeof(*bf));
  		goto error;
  	}
  	/* FIXME: make sure beacon frame IEs are fine and that the whole thing
  	 * is consistent */
  	result = 0;
  error:
  	return result;
  }
  
  /*
   * Handle UWB_RC_EVT_BEACON events
   *
   * We check the beacon cache to see how the received beacon fares. If
   * is there already we refresh the timestamp. If not we create a new
   * entry.
   *
   * According to the WHCI and WUSB specs, only one beacon frame is
   * allowed per notification block, so we don't bother about scanning
   * for more.
   */
  int uwbd_evt_handle_rc_beacon(struct uwb_event *evt)
  {
  	int result = -EINVAL;
  	struct uwb_rc *rc;
  	struct uwb_rc_evt_beacon *be;
  	struct uwb_beacon_frame *bf;
  	struct uwb_beca_e *bce;
  	unsigned long last_ts;
  
  	rc = evt->rc;
  	be = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon, rceb);
  	result = uwb_verify_beacon(rc, evt, be);
  	if (result < 0)
  		return result;
  
  	/* FIXME: handle alien beacons. */
  	if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
  	    be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
  		return -ENOSYS;
  	}
  
  	bf = (struct uwb_beacon_frame *) be->BeaconInfo;
  
  	/*
  	 * Drop beacons from devices with a NULL EUI-48 -- they cannot
  	 * be uniquely identified.
  	 *
  	 * It's expected that these will all be WUSB devices and they
  	 * have a WUSB specific connection method so ignoring them
  	 * here shouldn't be a problem.
  	 */
  	if (uwb_mac_addr_bcast(&bf->Device_Identifier))
  		return 0;
  
  	mutex_lock(&rc->uwb_beca.mutex);
  	bce = __uwb_beca_find_bymac(rc, &bf->Device_Identifier);
  	if (bce == NULL) {
  		/* Not in there, a new device is pinging */
  		uwb_beacon_print(evt->rc, be, bf);
  		bce = __uwb_beca_add(rc, be, bf, evt->ts_jiffies);
  		if (bce == NULL) {
  			mutex_unlock(&rc->uwb_beca.mutex);
  			return -ENOMEM;
  		}
  	}
  	mutex_unlock(&rc->uwb_beca.mutex);
  
  	mutex_lock(&bce->mutex);
  	/* purge old beacon data */
  	kfree(bce->be);
  
  	last_ts = bce->ts_jiffies;
  
  	/* Update commonly used fields */
  	bce->ts_jiffies = evt->ts_jiffies;
  	bce->be = be;
  	bce->dev_addr = bf->hdr.SrcAddr;
  	bce->mac_addr = &bf->Device_Identifier;
  	be->wBPSTOffset = le16_to_cpu(be->wBPSTOffset);
  	be->wBeaconInfoLength = le16_to_cpu(be->wBeaconInfoLength);
  	stats_add_sample(&bce->lqe_stats, be->bLQI - 7);
  	stats_add_sample(&bce->rssi_stats, be->bRSSI + 18);
  
  	/*
  	 * This might be a beacon from a new device.
  	 */
  	if (bce->uwb_dev == NULL)
  		uwbd_dev_onair(evt->rc, bce);
  
  	mutex_unlock(&bce->mutex);
  
  	return 1; /* we keep the event data */
  }
  
  /*
   * Handle UWB_RC_EVT_BEACON_SIZE events
   *
   * XXXXX
   */
  int uwbd_evt_handle_rc_beacon_size(struct uwb_event *evt)
  {
  	int result = -EINVAL;
  	struct device *dev = &evt->rc->uwb_dev.dev;
  	struct uwb_rc_evt_beacon_size *bs;
  
  	/* Is there enough data to decode the event? */
  	if (evt->notif.size < sizeof(*bs)) {
  		dev_err(dev, "BEACON SIZE notification: Not enough data to "
  			"decode (%zu vs %zu bytes needed)
  ",
  			evt->notif.size, sizeof(*bs));
  		goto error;
  	}
  	bs = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon_size, rceb);
  	if (0)
  		dev_info(dev, "Beacon size changed to %u bytes "
  			"(FIXME: action?)
  ", le16_to_cpu(bs->wNewBeaconSize));
  	else {
  		/* temporary hack until we do something with this message... */
  		static unsigned count;
  		if (++count % 1000 == 0)
  			dev_info(dev, "Beacon size changed %u times "
  				"(FIXME: action?)
  ", count);
  	}
  	result = 0;
  error:
  	return result;
  }
  
  /**
   * uwbd_evt_handle_rc_bp_slot_change - handle a BP_SLOT_CHANGE event
   * @evt: the BP_SLOT_CHANGE notification from the radio controller
   *
   * If the event indicates that no beacon period slots were available
   * then radio controller has transitioned to a non-beaconing state.
   * Otherwise, simply save the current beacon slot.
   */
  int uwbd_evt_handle_rc_bp_slot_change(struct uwb_event *evt)
  {
  	struct uwb_rc *rc = evt->rc;
  	struct device *dev = &rc->uwb_dev.dev;
  	struct uwb_rc_evt_bp_slot_change *bpsc;
  
  	if (evt->notif.size < sizeof(*bpsc)) {
  		dev_err(dev, "BP SLOT CHANGE event: Not enough data
  ");
  		return -EINVAL;
  	}
  	bpsc = container_of(evt->notif.rceb, struct uwb_rc_evt_bp_slot_change, rceb);
  
  	if (uwb_rc_evt_bp_slot_change_no_slot(bpsc)) {
  		dev_err(dev, "stopped beaconing: No free slots in BP
  ");
  		mutex_lock(&rc->uwb_dev.mutex);
  		rc->beaconing = -1;
  		mutex_unlock(&rc->uwb_dev.mutex);
  	} else
  		rc->uwb_dev.beacon_slot = uwb_rc_evt_bp_slot_change_slot_num(bpsc);
  
  	return 0;
  }
  
  /**
   * Handle UWB_RC_EVT_BPOIE_CHANGE events
   *
   * XXXXX
   */
  struct uwb_ie_bpo {
  	struct uwb_ie_hdr hdr;
  	u8                bp_length;
  	u8                data[];
  } __attribute__((packed));
  
  int uwbd_evt_handle_rc_bpoie_change(struct uwb_event *evt)
  {
  	int result = -EINVAL;
  	struct device *dev = &evt->rc->uwb_dev.dev;
  	struct uwb_rc_evt_bpoie_change *bpoiec;
  	struct uwb_ie_bpo *bpoie;
  	static unsigned count;	/* FIXME: this is a temp hack */
  	size_t iesize;
  
  	/* Is there enough data to decode it? */
  	if (evt->notif.size < sizeof(*bpoiec)) {
  		dev_err(dev, "BPOIEC notification: Not enough data to "
  			"decode (%zu vs %zu bytes needed)
  ",
  			evt->notif.size, sizeof(*bpoiec));
  		goto error;
  	}
  	bpoiec = container_of(evt->notif.rceb, struct uwb_rc_evt_bpoie_change, rceb);
  	iesize = le16_to_cpu(bpoiec->wBPOIELength);
  	if (iesize < sizeof(*bpoie)) {
  		dev_err(dev, "BPOIEC notification: Not enough IE data to "
  			"decode (%zu vs %zu bytes needed)
  ",
  			iesize, sizeof(*bpoie));
  		goto error;
  	}
  	if (++count % 1000 == 0)	/* Lame placeholder */
  		dev_info(dev, "BPOIE: %u changes received
  ", count);
  	/*
  	 * FIXME: At this point we should go over all the IEs in the
  	 *        bpoiec->BPOIE array and act on each.
  	 */
  	result = 0;
  error:
  	return result;
  }
  
  /*
   * Print beaconing state.
   */
  static ssize_t uwb_rc_beacon_show(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {
  	struct uwb_dev *uwb_dev = to_uwb_dev(dev);
  	struct uwb_rc *rc = uwb_dev->rc;
  	ssize_t result;
  
  	mutex_lock(&rc->uwb_dev.mutex);
  	result = sprintf(buf, "%d
  ", rc->beaconing);
  	mutex_unlock(&rc->uwb_dev.mutex);
  	return result;
  }
  
  /*
   * Start beaconing on the specified channel, or stop beaconing.
   */
  static ssize_t uwb_rc_beacon_store(struct device *dev,
  				   struct device_attribute *attr,
  				   const char *buf, size_t size)
  {
  	struct uwb_dev *uwb_dev = to_uwb_dev(dev);
  	struct uwb_rc *rc = uwb_dev->rc;
  	int channel;
  	ssize_t result = -EINVAL;
  
  	result = sscanf(buf, "%d", &channel);
  	if (result >= 1)
  		result = uwb_radio_force_channel(rc, channel);
  
  	return result < 0 ? result : size;
  }
  DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);