/*
   * This file contains helper code to handle channel
   * settings and keeping track of what is possible at
   * any point in time.
   *
   * Copyright 2009	Johannes Berg <johannes@sipsolutions.net>
   */

  #include <linux/export.h>

  #include <net/cfg80211.h>
  #include "core.h"
  
  struct ieee80211_channel *

  rdev_freq_to_chan(struct cfg80211_registered_device *rdev,

  		  int freq, enum nl80211_channel_type channel_type)
  {
  	struct ieee80211_channel *chan;
  	struct ieee80211_sta_ht_cap *ht_cap;

  
  	chan = ieee80211_get_channel(&rdev->wiphy, freq);
  
  	/* Primary channel not allowed */
  	if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)

  		return NULL;

  
  	if (channel_type == NL80211_CHAN_HT40MINUS &&
  	    chan->flags & IEEE80211_CHAN_NO_HT40MINUS)

  		return NULL;

  	else if (channel_type == NL80211_CHAN_HT40PLUS &&
  		 chan->flags & IEEE80211_CHAN_NO_HT40PLUS)

  		return NULL;

  
  	ht_cap = &rdev->wiphy.bands[chan->band]->ht_cap;
  
  	if (channel_type != NL80211_CHAN_NO_HT) {
  		if (!ht_cap->ht_supported)

  			return NULL;

  		if (channel_type != NL80211_CHAN_HT20 &&
  		    (!(ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) ||
  		    ht_cap->cap & IEEE80211_HT_CAP_40MHZ_INTOLERANT))

  			return NULL;

  	}

  	return chan;
  }

  int cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
  				  struct ieee80211_channel *chan,
  				  enum nl80211_channel_type channel_type)

  {
  	struct ieee80211_channel *sec_chan;
  	int diff;
  
  	switch (channel_type) {
  	case NL80211_CHAN_HT40PLUS:
  		diff = 20;

  		break;

  	case NL80211_CHAN_HT40MINUS:
  		diff = -20;

  		break;

  	default:
  		return false;
  	}
  
  	sec_chan = ieee80211_get_channel(wiphy, chan->center_freq + diff);
  	if (!sec_chan)
  		return false;
  
  	/* we'll need a DFS capability later */
  	if (sec_chan->flags & (IEEE80211_CHAN_DISABLED |
  			       IEEE80211_CHAN_PASSIVE_SCAN |
  			       IEEE80211_CHAN_NO_IBSS |
  			       IEEE80211_CHAN_RADAR))
  		return false;
  
  	return true;
  }

  EXPORT_SYMBOL(cfg80211_can_beacon_sec_chan);

  int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
  		      struct wireless_dev *wdev, int freq,
  		      enum nl80211_channel_type channel_type)

  {
  	struct ieee80211_channel *chan;
  	int result;

  	if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR)

  		wdev = NULL;
  
  	if (wdev) {
  		ASSERT_WDEV_LOCK(wdev);
  
  		if (!netif_running(wdev->netdev))
  			return -ENETDOWN;
  	}

  
  	if (!rdev->ops->set_channel)
  		return -EOPNOTSUPP;
  
  	chan = rdev_freq_to_chan(rdev, freq, channel_type);
  	if (!chan)
  		return -EINVAL;

  	/* Both channels should be able to initiate communication */
  	if (wdev && (wdev->iftype == NL80211_IFTYPE_ADHOC ||
  		     wdev->iftype == NL80211_IFTYPE_AP ||
  		     wdev->iftype == NL80211_IFTYPE_AP_VLAN ||
  		     wdev->iftype == NL80211_IFTYPE_MESH_POINT ||
  		     wdev->iftype == NL80211_IFTYPE_P2P_GO)) {
  		switch (channel_type) {
  		case NL80211_CHAN_HT40PLUS:
  		case NL80211_CHAN_HT40MINUS:

  			if (!cfg80211_can_beacon_sec_chan(&rdev->wiphy, chan,
  							  channel_type)) {

  				printk(KERN_DEBUG
  				       "cfg80211: Secondary channel not "
  				       "allowed to initiate communication
  ");
  				return -EINVAL;
  			}
  			break;
  		default:
  			break;
  		}
  	}

  	result = rdev->ops->set_channel(&rdev->wiphy,
  					wdev ? wdev->netdev : NULL,
  					chan, channel_type);

  	if (result)
  		return result;

  	if (wdev)
  		wdev->channel = chan;

  
  	return 0;
  }