/*
   * Copyright 2002-2005, Instant802 Networks, Inc.
   * Copyright 2005-2006, Devicescape Software, Inc.
   * Copyright 2007	Johannes Berg <johannes@sipsolutions.net>

   * Copyright 2008-2011	Luis R. Rodriguez <mcgrof@qca.qualcomm.com>

   *

   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   */

  /**
   * DOC: Wireless regulatory infrastructure

   *
   * The usual implementation is for a driver to read a device EEPROM to
   * determine which regulatory domain it should be operating under, then
   * looking up the allowable channels in a driver-local table and finally
   * registering those channels in the wiphy structure.
   *

   * Another set of compliance enforcement is for drivers to use their
   * own compliance limits which can be stored on the EEPROM. The host
   * driver or firmware may ensure these are used.
   *
   * In addition to all this we provide an extra layer of regulatory
   * conformance. For drivers which do not have any regulatory
   * information CRDA provides the complete regulatory solution.
   * For others it provides a community effort on further restrictions
   * to enhance compliance.
   *
   * Note: When number of rules --> infinity we will not be able to
   * index on alpha2 any more, instead we'll probably have to
   * rely on some SHA1 checksum of the regdomain for example.
   *

   */

  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>

  #include <linux/export.h>

  #include <linux/slab.h>

  #include <linux/list.h>

  #include <linux/ctype.h>

  #include <linux/nl80211.h>
  #include <linux/platform_device.h>

  #include <linux/moduleparam.h>

  #include <net/cfg80211.h>

  #include "core.h"

  #include "reg.h"

  #include "regdb.h"

  #include "nl80211.h"

  #ifdef CONFIG_CFG80211_REG_DEBUG

  #define REG_DBG_PRINT(format, args...)			\
  	printk(KERN_DEBUG pr_fmt(format), ##args)

  #else

  #define REG_DBG_PRINT(args...)

  #endif

  /**
   * enum reg_request_treatment - regulatory request treatment
   *
   * @REG_REQ_OK: continue processing the regulatory request
   * @REG_REQ_IGNORE: ignore the regulatory request
   * @REG_REQ_INTERSECT: the regulatory domain resulting from this request should
   *	be intersected with the current one.
   * @REG_REQ_ALREADY_SET: the regulatory request will not change the current
   *	regulatory settings, and no further processing is required.
   * @REG_REQ_USER_HINT_HANDLED: a non alpha2  user hint was handled and no
   *	further processing is required, i.e., not need to update last_request
   *	etc. This should be used for user hints that do not provide an alpha2
   *	but some other type of regulatory hint, i.e., indoor operation.
   */

  enum reg_request_treatment {
  	REG_REQ_OK,
  	REG_REQ_IGNORE,
  	REG_REQ_INTERSECT,
  	REG_REQ_ALREADY_SET,

  	REG_REQ_USER_HINT_HANDLED,

  };

  static struct regulatory_request core_request_world = {
  	.initiator = NL80211_REGDOM_SET_BY_CORE,
  	.alpha2[0] = '0',
  	.alpha2[1] = '0',
  	.intersect = false,
  	.processed = true,
  	.country_ie_env = ENVIRON_ANY,
  };

  /*
   * Receipt of information from last regulatory request,
   * protected by RTNL (and can be accessed with RCU protection)
   */

  static struct regulatory_request __rcu *last_request =
  	(void __rcu *)&core_request_world;

  /* To trigger userspace events */
  static struct platform_device *reg_pdev;

  /*
   * Central wireless core regulatory domains, we only need two,

   * the current one and a world regulatory domain in case we have no

   * information to give us an alpha2.

   * (protected by RTNL, can be read under RCU)

   */

  const struct ieee80211_regdomain __rcu *cfg80211_regdomain;

  /*

   * Number of devices that registered to the core
   * that support cellular base station regulatory hints

   * (protected by RTNL)

   */
  static int reg_num_devs_support_basehint;

  /*
   * State variable indicating if the platform on which the devices
   * are attached is operating in an indoor environment. The state variable
   * is relevant for all registered devices.
   * (protected by RTNL)
   */
  static bool reg_is_indoor;

  static const struct ieee80211_regdomain *get_cfg80211_regdom(void)
  {

  	return rtnl_dereference(cfg80211_regdomain);

  }
  
  static const struct ieee80211_regdomain *get_wiphy_regdom(struct wiphy *wiphy)
  {

  	return rtnl_dereference(wiphy->regd);

  }

  static const char *reg_dfs_region_str(enum nl80211_dfs_regions dfs_region)
  {
  	switch (dfs_region) {
  	case NL80211_DFS_UNSET:
  		return "unset";
  	case NL80211_DFS_FCC:
  		return "FCC";
  	case NL80211_DFS_ETSI:
  		return "ETSI";
  	case NL80211_DFS_JP:
  		return "JP";
  	}
  	return "Unknown";
  }

  enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy)
  {
  	const struct ieee80211_regdomain *regd = NULL;
  	const struct ieee80211_regdomain *wiphy_regd = NULL;
  
  	regd = get_cfg80211_regdom();
  	if (!wiphy)
  		goto out;
  
  	wiphy_regd = get_wiphy_regdom(wiphy);
  	if (!wiphy_regd)
  		goto out;
  
  	if (wiphy_regd->dfs_region == regd->dfs_region)
  		goto out;
  
  	REG_DBG_PRINT("%s: device specific dfs_region "
  		      "(%s) disagrees with cfg80211's "
  		      "central dfs_region (%s)
  ",
  		      dev_name(&wiphy->dev),
  		      reg_dfs_region_str(wiphy_regd->dfs_region),
  		      reg_dfs_region_str(regd->dfs_region));
  
  out:
  	return regd->dfs_region;
  }

  static void rcu_free_regdom(const struct ieee80211_regdomain *r)
  {
  	if (!r)
  		return;
  	kfree_rcu((struct ieee80211_regdomain *)r, rcu_head);
  }

  static struct regulatory_request *get_last_request(void)
  {

  	return rcu_dereference_rtnl(last_request);

  }

  /* Used to queue up regulatory hints */

  static LIST_HEAD(reg_requests_list);
  static spinlock_t reg_requests_lock;

  /* Used to queue up beacon hints for review */
  static LIST_HEAD(reg_pending_beacons);
  static spinlock_t reg_pending_beacons_lock;
  
  /* Used to keep track of processed beacon hints */
  static LIST_HEAD(reg_beacon_list);
  
  struct reg_beacon {
  	struct list_head list;
  	struct ieee80211_channel chan;
  };

  static void reg_todo(struct work_struct *work);
  static DECLARE_WORK(reg_work, reg_todo);

  static void reg_timeout_work(struct work_struct *work);
  static DECLARE_DELAYED_WORK(reg_timeout, reg_timeout_work);

  /* We keep a static world regulatory domain in case of the absence of CRDA */
  static const struct ieee80211_regdomain world_regdom = {

  	.n_reg_rules = 6,

  	.alpha2 =  "00",
  	.reg_rules = {

  		/* IEEE 802.11b/g, channels 1..11 */
  		REG_RULE(2412-10, 2462+10, 40, 6, 20, 0),

  		/* IEEE 802.11b/g, channels 12..13. */
  		REG_RULE(2467-10, 2472+10, 40, 6, 20,

  			NL80211_RRF_NO_IR),

  		/* IEEE 802.11 channel 14 - Only JP enables
  		 * this and for 802.11b only */
  		REG_RULE(2484-10, 2484+10, 20, 6, 20,

  			NL80211_RRF_NO_IR |

  			NL80211_RRF_NO_OFDM),
  		/* IEEE 802.11a, channel 36..48 */

  		REG_RULE(5180-10, 5240+10, 160, 6, 20,

                          NL80211_RRF_NO_IR),

  		/* IEEE 802.11a, channel 52..64 - DFS required */
  		REG_RULE(5260-10, 5320+10, 160, 6, 20,

  			NL80211_RRF_NO_IR |

  			NL80211_RRF_DFS),
  
  		/* IEEE 802.11a, channel 100..144 - DFS required */
  		REG_RULE(5500-10, 5720+10, 160, 6, 20,

  			NL80211_RRF_NO_IR |

  			NL80211_RRF_DFS),

  
  		/* IEEE 802.11a, channel 149..165 */

  		REG_RULE(5745-10, 5825+10, 80, 6, 20,

  			NL80211_RRF_NO_IR),

  
  		/* IEEE 802.11ad (60gHz), channels 1..3 */
  		REG_RULE(56160+2160*1-1080, 56160+2160*3+1080, 2160, 0, 0, 0),

  	}
  };

  /* protected by RTNL */

  static const struct ieee80211_regdomain *cfg80211_world_regdom =
  	&world_regdom;

  static char *ieee80211_regdom = "00";

  static char user_alpha2[2];

  module_param(ieee80211_regdom, charp, 0444);
  MODULE_PARM_DESC(ieee80211_regdom, "IEEE 802.11 regulatory domain code");

  static void reg_free_request(struct regulatory_request *request)

  {

  	if (request != get_last_request())
  		kfree(request);
  }
  
  static void reg_free_last_request(void)
  {
  	struct regulatory_request *lr = get_last_request();

  	if (lr != &core_request_world && lr)
  		kfree_rcu(lr, rcu_head);
  }

  static void reg_update_last_request(struct regulatory_request *request)
  {

  	struct regulatory_request *lr;
  
  	lr = get_last_request();
  	if (lr == request)
  		return;

  	reg_free_last_request();

  	rcu_assign_pointer(last_request, request);
  }

  static void reset_regdomains(bool full_reset,
  			     const struct ieee80211_regdomain *new_regdom)

  {

  	const struct ieee80211_regdomain *r;

  	ASSERT_RTNL();

  	r = get_cfg80211_regdom();

  	/* avoid freeing static information or freeing something twice */

  	if (r == cfg80211_world_regdom)
  		r = NULL;

  	if (cfg80211_world_regdom == &world_regdom)
  		cfg80211_world_regdom = NULL;

  	if (r == &world_regdom)
  		r = NULL;

  	rcu_free_regdom(r);
  	rcu_free_regdom(cfg80211_world_regdom);

  	cfg80211_world_regdom = &world_regdom;

  	rcu_assign_pointer(cfg80211_regdomain, new_regdom);

  
  	if (!full_reset)
  		return;

  	reg_update_last_request(&core_request_world);

  }

  /*
   * Dynamic world regulatory domain requested by the wireless
   * core upon initialization
   */

  static void update_world_regdomain(const struct ieee80211_regdomain *rd)

  {

  	struct regulatory_request *lr;

  	lr = get_last_request();
  
  	WARN_ON(!lr);

  	reset_regdomains(false, rd);

  
  	cfg80211_world_regdom = rd;

  }

  bool is_world_regdom(const char *alpha2)

  {
  	if (!alpha2)
  		return false;

  	return alpha2[0] == '0' && alpha2[1] == '0';

  }

  static bool is_alpha2_set(const char *alpha2)

  {
  	if (!alpha2)
  		return false;

  	return alpha2[0] && alpha2[1];

  }

  static bool is_unknown_alpha2(const char *alpha2)

  {
  	if (!alpha2)
  		return false;

  	/*
  	 * Special case where regulatory domain was built by driver
  	 * but a specific alpha2 cannot be determined
  	 */

  	return alpha2[0] == '9' && alpha2[1] == '9';

  }

  static bool is_intersected_alpha2(const char *alpha2)
  {
  	if (!alpha2)
  		return false;

  	/*
  	 * Special case where regulatory domain is the

  	 * result of an intersection between two regulatory domain

  	 * structures
  	 */

  	return alpha2[0] == '9' && alpha2[1] == '8';

  }

  static bool is_an_alpha2(const char *alpha2)

  {
  	if (!alpha2)
  		return false;

  	return isalpha(alpha2[0]) && isalpha(alpha2[1]);

  }

  static bool alpha2_equal(const char *alpha2_x, const char *alpha2_y)

  {
  	if (!alpha2_x || !alpha2_y)
  		return false;

  	return alpha2_x[0] == alpha2_y[0] && alpha2_x[1] == alpha2_y[1];

  }

  static bool regdom_changes(const char *alpha2)

  {

  	const struct ieee80211_regdomain *r = get_cfg80211_regdom();

  	if (!r)

  		return true;

  	return !alpha2_equal(r->alpha2, alpha2);

  }

  /*
   * The NL80211_REGDOM_SET_BY_USER regdom alpha2 is cached, this lets
   * you know if a valid regulatory hint with NL80211_REGDOM_SET_BY_USER
   * has ever been issued.
   */
  static bool is_user_regdom_saved(void)
  {
  	if (user_alpha2[0] == '9' && user_alpha2[1] == '7')
  		return false;
  
  	/* This would indicate a mistake on the design */

  	if (WARN(!is_world_regdom(user_alpha2) && !is_an_alpha2(user_alpha2),

  		 "Unexpected user alpha2: %c%c
  ",

  		 user_alpha2[0], user_alpha2[1]))

  		return false;
  
  	return true;
  }

  static const struct ieee80211_regdomain *
  reg_copy_regd(const struct ieee80211_regdomain *src_regd)

  {
  	struct ieee80211_regdomain *regd;

  	int size_of_regd;

  	unsigned int i;

  	size_of_regd =
  		sizeof(struct ieee80211_regdomain) +
  		src_regd->n_reg_rules * sizeof(struct ieee80211_reg_rule);

  
  	regd = kzalloc(size_of_regd, GFP_KERNEL);
  	if (!regd)

  		return ERR_PTR(-ENOMEM);

  
  	memcpy(regd, src_regd, sizeof(struct ieee80211_regdomain));
  
  	for (i = 0; i < src_regd->n_reg_rules; i++)
  		memcpy(&regd->reg_rules[i], &src_regd->reg_rules[i],

  		       sizeof(struct ieee80211_reg_rule));

  	return regd;

  }
  
  #ifdef CONFIG_CFG80211_INTERNAL_REGDB
  struct reg_regdb_search_request {
  	char alpha2[2];
  	struct list_head list;
  };
  
  static LIST_HEAD(reg_regdb_search_list);

  static DEFINE_MUTEX(reg_regdb_search_mutex);

  
  static void reg_regdb_search(struct work_struct *work)
  {
  	struct reg_regdb_search_request *request;

  	const struct ieee80211_regdomain *curdom, *regdom = NULL;
  	int i;

  	rtnl_lock();

  	mutex_lock(&reg_regdb_search_mutex);

  	while (!list_empty(&reg_regdb_search_list)) {
  		request = list_first_entry(&reg_regdb_search_list,
  					   struct reg_regdb_search_request,
  					   list);
  		list_del(&request->list);

  		for (i = 0; i < reg_regdb_size; i++) {

  			curdom = reg_regdb[i];

  			if (alpha2_equal(request->alpha2, curdom->alpha2)) {

  				regdom = reg_copy_regd(curdom);

  				break;
  			}
  		}
  
  		kfree(request);
  	}

  	mutex_unlock(&reg_regdb_search_mutex);

  	if (!IS_ERR_OR_NULL(regdom))

  		set_regdom(regdom);

  	rtnl_unlock();

  }
  
  static DECLARE_WORK(reg_regdb_work, reg_regdb_search);
  
  static void reg_regdb_query(const char *alpha2)
  {
  	struct reg_regdb_search_request *request;
  
  	if (!alpha2)
  		return;
  
  	request = kzalloc(sizeof(struct reg_regdb_search_request), GFP_KERNEL);
  	if (!request)
  		return;
  
  	memcpy(request->alpha2, alpha2, 2);

  	mutex_lock(&reg_regdb_search_mutex);

  	list_add_tail(&request->list, &reg_regdb_search_list);

  	mutex_unlock(&reg_regdb_search_mutex);

  
  	schedule_work(&reg_regdb_work);
  }

  
  /* Feel free to add any other sanity checks here */
  static void reg_regdb_size_check(void)
  {
  	/* We should ideally BUILD_BUG_ON() but then random builds would fail */
  	WARN_ONCE(!reg_regdb_size, "db.txt is empty, you should update it...");
  }

  #else

  static inline void reg_regdb_size_check(void) {}

  static inline void reg_regdb_query(const char *alpha2) {}
  #endif /* CONFIG_CFG80211_INTERNAL_REGDB */

  /*
   * This lets us keep regulatory code which is updated on a regulatory

   * basis in userspace.

   */

  static int call_crda(const char *alpha2)
  {

  	char country[12];
  	char *env[] = { country, NULL };
  
  	snprintf(country, sizeof(country), "COUNTRY=%c%c",
  		 alpha2[0], alpha2[1]);

  	if (!is_world_regdom((char *) alpha2))

  		pr_info("Calling CRDA for country: %c%c
  ",

  			alpha2[0], alpha2[1]);
  	else

  		pr_info("Calling CRDA to update world regulatory domain
  ");

  	/* query internal regulatory database (if it exists) */
  	reg_regdb_query(alpha2);

  	return kobject_uevent_env(&reg_pdev->dev.kobj, KOBJ_CHANGE, env);

  }

  static enum reg_request_treatment
  reg_call_crda(struct regulatory_request *request)
  {
  	if (call_crda(request->alpha2))
  		return REG_REQ_IGNORE;
  	return REG_REQ_OK;
  }

  bool reg_is_valid_request(const char *alpha2)

  {

  	struct regulatory_request *lr = get_last_request();

  	if (!lr || lr->processed)

  		return false;

  	return alpha2_equal(lr->alpha2, alpha2);

  }

  static const struct ieee80211_regdomain *reg_get_regdomain(struct wiphy *wiphy)
  {
  	struct regulatory_request *lr = get_last_request();
  
  	/*
  	 * Follow the driver's regulatory domain, if present, unless a country
  	 * IE has been processed or a user wants to help complaince further
  	 */
  	if (lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
  	    lr->initiator != NL80211_REGDOM_SET_BY_USER &&
  	    wiphy->regd)
  		return get_wiphy_regdom(wiphy);
  
  	return get_cfg80211_regdom();
  }

  unsigned int reg_get_max_bandwidth(const struct ieee80211_regdomain *rd,
  				   const struct ieee80211_reg_rule *rule)
  {
  	const struct ieee80211_freq_range *freq_range = &rule->freq_range;
  	const struct ieee80211_freq_range *freq_range_tmp;
  	const struct ieee80211_reg_rule *tmp;
  	u32 start_freq, end_freq, idx, no;
  
  	for (idx = 0; idx < rd->n_reg_rules; idx++)
  		if (rule == &rd->reg_rules[idx])
  			break;
  
  	if (idx == rd->n_reg_rules)
  		return 0;
  
  	/* get start_freq */
  	no = idx;
  
  	while (no) {
  		tmp = &rd->reg_rules[--no];
  		freq_range_tmp = &tmp->freq_range;
  
  		if (freq_range_tmp->end_freq_khz < freq_range->start_freq_khz)
  			break;

  		freq_range = freq_range_tmp;
  	}
  
  	start_freq = freq_range->start_freq_khz;
  
  	/* get end_freq */
  	freq_range = &rule->freq_range;
  	no = idx;
  
  	while (no < rd->n_reg_rules - 1) {
  		tmp = &rd->reg_rules[++no];
  		freq_range_tmp = &tmp->freq_range;
  
  		if (freq_range_tmp->start_freq_khz > freq_range->end_freq_khz)
  			break;

  		freq_range = freq_range_tmp;
  	}
  
  	end_freq = freq_range->end_freq_khz;
  
  	return end_freq - start_freq;
  }

  /* Sanity check on a regulatory rule */

  static bool is_valid_reg_rule(const struct ieee80211_reg_rule *rule)

  {

  	const struct ieee80211_freq_range *freq_range = &rule->freq_range;

  	u32 freq_diff;

  	if (freq_range->start_freq_khz <= 0 || freq_range->end_freq_khz <= 0)

  		return false;
  
  	if (freq_range->start_freq_khz > freq_range->end_freq_khz)
  		return false;
  
  	freq_diff = freq_range->end_freq_khz - freq_range->start_freq_khz;

  	if (freq_range->end_freq_khz <= freq_range->start_freq_khz ||

  	    freq_range->max_bandwidth_khz > freq_diff)

  		return false;
  
  	return true;
  }

  static bool is_valid_rd(const struct ieee80211_regdomain *rd)

  {

  	const struct ieee80211_reg_rule *reg_rule = NULL;

  	unsigned int i;

  	if (!rd->n_reg_rules)
  		return false;

  	if (WARN_ON(rd->n_reg_rules > NL80211_MAX_SUPP_REG_RULES))
  		return false;

  	for (i = 0; i < rd->n_reg_rules; i++) {
  		reg_rule = &rd->reg_rules[i];
  		if (!is_valid_reg_rule(reg_rule))
  			return false;
  	}
  
  	return true;

  }

  static bool reg_does_bw_fit(const struct ieee80211_freq_range *freq_range,

  			    u32 center_freq_khz, u32 bw_khz)

  {

  	u32 start_freq_khz, end_freq_khz;
  
  	start_freq_khz = center_freq_khz - (bw_khz/2);
  	end_freq_khz = center_freq_khz + (bw_khz/2);
  
  	if (start_freq_khz >= freq_range->start_freq_khz &&
  	    end_freq_khz <= freq_range->end_freq_khz)
  		return true;
  
  	return false;

  }

  /**
   * freq_in_rule_band - tells us if a frequency is in a frequency band
   * @freq_range: frequency rule we want to query
   * @freq_khz: frequency we are inquiring about
   *
   * This lets us know if a specific frequency rule is or is not relevant to
   * a specific frequency's band. Bands are device specific and artificial

   * definitions (the "2.4 GHz band", the "5 GHz band" and the "60GHz band"),
   * however it is safe for now to assume that a frequency rule should not be
   * part of a frequency's band if the start freq or end freq are off by more
   * than 2 GHz for the 2.4 and 5 GHz bands, and by more than 10 GHz for the
   * 60 GHz band.

   * This resolution can be lowered and should be considered as we add
   * regulatory rule support for other "bands".
   **/
  static bool freq_in_rule_band(const struct ieee80211_freq_range *freq_range,

  			      u32 freq_khz)

  {
  #define ONE_GHZ_IN_KHZ	1000000

  	/*
  	 * From 802.11ad: directional multi-gigabit (DMG):
  	 * Pertaining to operation in a frequency band containing a channel
  	 * with the Channel starting frequency above 45 GHz.
  	 */
  	u32 limit = freq_khz > 45 * ONE_GHZ_IN_KHZ ?
  			10 * ONE_GHZ_IN_KHZ : 2 * ONE_GHZ_IN_KHZ;
  	if (abs(freq_khz - freq_range->start_freq_khz) <= limit)

  		return true;

  	if (abs(freq_khz - freq_range->end_freq_khz) <= limit)

  		return true;
  	return false;
  #undef ONE_GHZ_IN_KHZ
  }

  /*

   * Later on we can perhaps use the more restrictive DFS
   * region but we don't have information for that yet so
   * for now simply disallow conflicts.
   */
  static enum nl80211_dfs_regions
  reg_intersect_dfs_region(const enum nl80211_dfs_regions dfs_region1,
  			 const enum nl80211_dfs_regions dfs_region2)
  {
  	if (dfs_region1 != dfs_region2)
  		return NL80211_DFS_UNSET;
  	return dfs_region1;
  }
  
  /*

   * Helper for regdom_intersect(), this does the real
   * mathematical intersection fun
   */

  static int reg_rules_intersect(const struct ieee80211_regdomain *rd1,
  			       const struct ieee80211_regdomain *rd2,
  			       const struct ieee80211_reg_rule *rule1,

  			       const struct ieee80211_reg_rule *rule2,
  			       struct ieee80211_reg_rule *intersected_rule)

  {
  	const struct ieee80211_freq_range *freq_range1, *freq_range2;
  	struct ieee80211_freq_range *freq_range;
  	const struct ieee80211_power_rule *power_rule1, *power_rule2;
  	struct ieee80211_power_rule *power_rule;

  	u32 freq_diff, max_bandwidth1, max_bandwidth2;

  
  	freq_range1 = &rule1->freq_range;
  	freq_range2 = &rule2->freq_range;
  	freq_range = &intersected_rule->freq_range;
  
  	power_rule1 = &rule1->power_rule;
  	power_rule2 = &rule2->power_rule;
  	power_rule = &intersected_rule->power_rule;
  
  	freq_range->start_freq_khz = max(freq_range1->start_freq_khz,

  					 freq_range2->start_freq_khz);

  	freq_range->end_freq_khz = min(freq_range1->end_freq_khz,

  				       freq_range2->end_freq_khz);

  
  	max_bandwidth1 = freq_range1->max_bandwidth_khz;
  	max_bandwidth2 = freq_range2->max_bandwidth_khz;

  	if (rule1->flags & NL80211_RRF_AUTO_BW)
  		max_bandwidth1 = reg_get_max_bandwidth(rd1, rule1);
  	if (rule2->flags & NL80211_RRF_AUTO_BW)
  		max_bandwidth2 = reg_get_max_bandwidth(rd2, rule2);

  
  	freq_range->max_bandwidth_khz = min(max_bandwidth1, max_bandwidth2);

  	intersected_rule->flags = rule1->flags | rule2->flags;
  
  	/*
  	 * In case NL80211_RRF_AUTO_BW requested for both rules
  	 * set AUTO_BW in intersected rule also. Next we will
  	 * calculate BW correctly in handle_channel function.
  	 * In other case remove AUTO_BW flag while we calculate
  	 * maximum bandwidth correctly and auto calculation is
  	 * not required.
  	 */
  	if ((rule1->flags & NL80211_RRF_AUTO_BW) &&
  	    (rule2->flags & NL80211_RRF_AUTO_BW))
  		intersected_rule->flags |= NL80211_RRF_AUTO_BW;
  	else
  		intersected_rule->flags &= ~NL80211_RRF_AUTO_BW;

  	freq_diff = freq_range->end_freq_khz - freq_range->start_freq_khz;
  	if (freq_range->max_bandwidth_khz > freq_diff)
  		freq_range->max_bandwidth_khz = freq_diff;
  
  	power_rule->max_eirp = min(power_rule1->max_eirp,
  		power_rule2->max_eirp);
  	power_rule->max_antenna_gain = min(power_rule1->max_antenna_gain,
  		power_rule2->max_antenna_gain);

  	intersected_rule->dfs_cac_ms = max(rule1->dfs_cac_ms,
  					   rule2->dfs_cac_ms);

  	if (!is_valid_reg_rule(intersected_rule))
  		return -EINVAL;
  
  	return 0;
  }
  
  /**
   * regdom_intersect - do the intersection between two regulatory domains
   * @rd1: first regulatory domain
   * @rd2: second regulatory domain
   *
   * Use this function to get the intersection between two regulatory domains.
   * Once completed we will mark the alpha2 for the rd as intersected, "98",
   * as no one single alpha2 can represent this regulatory domain.
   *
   * Returns a pointer to the regulatory domain structure which will hold the
   * resulting intersection of rules between rd1 and rd2. We will
   * kzalloc() this structure for you.
   */

  static struct ieee80211_regdomain *
  regdom_intersect(const struct ieee80211_regdomain *rd1,
  		 const struct ieee80211_regdomain *rd2)

  {
  	int r, size_of_regd;
  	unsigned int x, y;
  	unsigned int num_rules = 0, rule_idx = 0;
  	const struct ieee80211_reg_rule *rule1, *rule2;
  	struct ieee80211_reg_rule *intersected_rule;
  	struct ieee80211_regdomain *rd;
  	/* This is just a dummy holder to help us count */

  	struct ieee80211_reg_rule dummy_rule;

  
  	if (!rd1 || !rd2)
  		return NULL;

  	/*
  	 * First we get a count of the rules we'll need, then we actually

  	 * build them. This is to so we can malloc() and free() a
  	 * regdomain once. The reason we use reg_rules_intersect() here
  	 * is it will return -EINVAL if the rule computed makes no sense.

  	 * All rules that do check out OK are valid.
  	 */

  
  	for (x = 0; x < rd1->n_reg_rules; x++) {
  		rule1 = &rd1->reg_rules[x];
  		for (y = 0; y < rd2->n_reg_rules; y++) {
  			rule2 = &rd2->reg_rules[y];

  			if (!reg_rules_intersect(rd1, rd2, rule1, rule2,
  						 &dummy_rule))

  				num_rules++;

  		}
  	}
  
  	if (!num_rules)
  		return NULL;
  
  	size_of_regd = sizeof(struct ieee80211_regdomain) +

  		       num_rules * sizeof(struct ieee80211_reg_rule);

  
  	rd = kzalloc(size_of_regd, GFP_KERNEL);
  	if (!rd)
  		return NULL;

  	for (x = 0; x < rd1->n_reg_rules && rule_idx < num_rules; x++) {

  		rule1 = &rd1->reg_rules[x];

  		for (y = 0; y < rd2->n_reg_rules && rule_idx < num_rules; y++) {

  			rule2 = &rd2->reg_rules[y];

  			/*
  			 * This time around instead of using the stack lets

  			 * write to the target rule directly saving ourselves

  			 * a memcpy()
  			 */

  			intersected_rule = &rd->reg_rules[rule_idx];

  			r = reg_rules_intersect(rd1, rd2, rule1, rule2,
  						intersected_rule);

  			/*
  			 * No need to memset here the intersected rule here as
  			 * we're not using the stack anymore
  			 */

  			if (r)
  				continue;
  			rule_idx++;
  		}
  	}
  
  	if (rule_idx != num_rules) {
  		kfree(rd);
  		return NULL;
  	}
  
  	rd->n_reg_rules = num_rules;
  	rd->alpha2[0] = '9';
  	rd->alpha2[1] = '8';

  	rd->dfs_region = reg_intersect_dfs_region(rd1->dfs_region,
  						  rd2->dfs_region);

  
  	return rd;
  }

  /*
   * XXX: add support for the rest of enum nl80211_reg_rule_flags, we may
   * want to just have the channel structure use these
   */

  static u32 map_regdom_flags(u32 rd_flags)
  {
  	u32 channel_flags = 0;

  	if (rd_flags & NL80211_RRF_NO_IR_ALL)
  		channel_flags |= IEEE80211_CHAN_NO_IR;

  	if (rd_flags & NL80211_RRF_DFS)
  		channel_flags |= IEEE80211_CHAN_RADAR;

  	if (rd_flags & NL80211_RRF_NO_OFDM)
  		channel_flags |= IEEE80211_CHAN_NO_OFDM;

  	if (rd_flags & NL80211_RRF_NO_OUTDOOR)
  		channel_flags |= IEEE80211_CHAN_INDOOR_ONLY;

  	return channel_flags;
  }

  static const struct ieee80211_reg_rule *
  freq_reg_info_regd(struct wiphy *wiphy, u32 center_freq,
  		   const struct ieee80211_regdomain *regd)

  {
  	int i;

  	bool band_rule_found = false;

  	bool bw_fits = false;

  	if (!regd)

  		return ERR_PTR(-EINVAL);

  	for (i = 0; i < regd->n_reg_rules; i++) {

  		const struct ieee80211_reg_rule *rr;
  		const struct ieee80211_freq_range *fr = NULL;

  		rr = &regd->reg_rules[i];

  		fr = &rr->freq_range;

  		/*
  		 * We only need to know if one frequency rule was

  		 * was in center_freq's band, that's enough, so lets

  		 * not overwrite it once found
  		 */

  		if (!band_rule_found)
  			band_rule_found = freq_in_rule_band(fr, center_freq);

  		bw_fits = reg_does_bw_fit(fr, center_freq, MHZ_TO_KHZ(5));

  		if (band_rule_found && bw_fits)
  			return rr;

  	}

  	if (!band_rule_found)

  		return ERR_PTR(-ERANGE);

  	return ERR_PTR(-EINVAL);

  }

  const struct ieee80211_reg_rule *freq_reg_info(struct wiphy *wiphy,
  					       u32 center_freq)

  {

  	const struct ieee80211_regdomain *regd;

  	regd = reg_get_regdomain(wiphy);

  	return freq_reg_info_regd(wiphy, center_freq, regd);

  }

  EXPORT_SYMBOL(freq_reg_info);

  const char *reg_initiator_name(enum nl80211_reg_initiator initiator)

  {
  	switch (initiator) {
  	case NL80211_REGDOM_SET_BY_CORE:

  		return "core";

  	case NL80211_REGDOM_SET_BY_USER:

  		return "user";

  	case NL80211_REGDOM_SET_BY_DRIVER:

  		return "driver";

  	case NL80211_REGDOM_SET_BY_COUNTRY_IE:

  		return "country IE";

  	default:
  		WARN_ON(1);

  		return "bug";

  	}
  }

  EXPORT_SYMBOL(reg_initiator_name);

  #ifdef CONFIG_CFG80211_REG_DEBUG

  static void chan_reg_rule_print_dbg(const struct ieee80211_regdomain *regd,
  				    struct ieee80211_channel *chan,

  				    const struct ieee80211_reg_rule *reg_rule)
  {
  	const struct ieee80211_power_rule *power_rule;
  	const struct ieee80211_freq_range *freq_range;

  	char max_antenna_gain[32], bw[32];

  
  	power_rule = &reg_rule->power_rule;
  	freq_range = &reg_rule->freq_range;
  
  	if (!power_rule->max_antenna_gain)

  		snprintf(max_antenna_gain, sizeof(max_antenna_gain), "N/A");

  	else

  		snprintf(max_antenna_gain, sizeof(max_antenna_gain), "%d",
  			 power_rule->max_antenna_gain);
  
  	if (reg_rule->flags & NL80211_RRF_AUTO_BW)
  		snprintf(bw, sizeof(bw), "%d KHz, %d KHz AUTO",
  			 freq_range->max_bandwidth_khz,
  			 reg_get_max_bandwidth(regd, reg_rule));
  	else
  		snprintf(bw, sizeof(bw), "%d KHz",
  			 freq_range->max_bandwidth_khz);

  	REG_DBG_PRINT("Updating information on frequency %d MHz with regulatory rule:
  ",
  		      chan->center_freq);

  	REG_DBG_PRINT("%d KHz - %d KHz @ %s), (%s mBi, %d mBm)
  ",

  		      freq_range->start_freq_khz, freq_range->end_freq_khz,

  		      bw, max_antenna_gain,

  		      power_rule->max_eirp);
  }
  #else

  static void chan_reg_rule_print_dbg(const struct ieee80211_regdomain *regd,
  				    struct ieee80211_channel *chan,

  				    const struct ieee80211_reg_rule *reg_rule)
  {
  	return;
  }

  #endif

  /* Find an ieee80211_reg_rule such that a 5MHz channel with frequency
   * chan->center_freq fits there.
   * If there is no such reg_rule, disable the channel, otherwise set the
   * flags corresponding to the bandwidths allowed in the particular reg_rule

   */

  static void handle_channel(struct wiphy *wiphy,
  			   enum nl80211_reg_initiator initiator,

  			   struct ieee80211_channel *chan)

  {

  	u32 flags, bw_flags = 0;

  	const struct ieee80211_reg_rule *reg_rule = NULL;
  	const struct ieee80211_power_rule *power_rule = NULL;

  	const struct ieee80211_freq_range *freq_range = NULL;

  	struct wiphy *request_wiphy = NULL;

  	struct regulatory_request *lr = get_last_request();

  	const struct ieee80211_regdomain *regd;
  	u32 max_bandwidth_khz;

  	request_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);

  
  	flags = chan->orig_flags;

  	reg_rule = freq_reg_info(wiphy, MHZ_TO_KHZ(chan->center_freq));
  	if (IS_ERR(reg_rule)) {

  		/*
  		 * We will disable all channels that do not match our

  		 * received regulatory rule unless the hint is coming

  		 * from a Country IE and the Country IE had no information
  		 * about a band. The IEEE 802.11 spec allows for an AP
  		 * to send only a subset of the regulatory rules allowed,
  		 * so an AP in the US that only supports 2.4 GHz may only send
  		 * a country IE with information for the 2.4 GHz band
  		 * while 5 GHz is still supported.
  		 */
  		if (initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&

  		    PTR_ERR(reg_rule) == -ERANGE)

  			return;

  		if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
  		    request_wiphy && request_wiphy == wiphy &&

  		    request_wiphy->regulatory_flags & REGULATORY_STRICT_REG) {

  			REG_DBG_PRINT("Disabling freq %d MHz for good
  ",
  				      chan->center_freq);
  			chan->orig_flags |= IEEE80211_CHAN_DISABLED;
  			chan->flags = chan->orig_flags;
  		} else {
  			REG_DBG_PRINT("Disabling freq %d MHz
  ",
  				      chan->center_freq);
  			chan->flags |= IEEE80211_CHAN_DISABLED;
  		}

  		return;

  	}

  	regd = reg_get_regdomain(wiphy);
  	chan_reg_rule_print_dbg(regd, chan, reg_rule);

  	power_rule = &reg_rule->power_rule;

  	freq_range = &reg_rule->freq_range;

  	max_bandwidth_khz = freq_range->max_bandwidth_khz;
  	/* Check if auto calculation requested */

  	if (reg_rule->flags & NL80211_RRF_AUTO_BW)

  		max_bandwidth_khz = reg_get_max_bandwidth(regd, reg_rule);

  	if (max_bandwidth_khz < MHZ_TO_KHZ(10))
  		bw_flags = IEEE80211_CHAN_NO_10MHZ;
  	if (max_bandwidth_khz < MHZ_TO_KHZ(20))
  		bw_flags |= IEEE80211_CHAN_NO_20MHZ;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(40))

  		bw_flags |= IEEE80211_CHAN_NO_HT40;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(80))

  		bw_flags |= IEEE80211_CHAN_NO_80MHZ;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(160))

  		bw_flags |= IEEE80211_CHAN_NO_160MHZ;

  	if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER &&

  	    request_wiphy && request_wiphy == wiphy &&

  	    request_wiphy->regulatory_flags & REGULATORY_STRICT_REG) {

  		/*

  		 * This guarantees the driver's requested regulatory domain

  		 * will always be used as a base for further regulatory

  		 * settings
  		 */

  		chan->flags = chan->orig_flags =

  			map_regdom_flags(reg_rule->flags) | bw_flags;

  		chan->max_antenna_gain = chan->orig_mag =
  			(int) MBI_TO_DBI(power_rule->max_antenna_gain);

  		chan->max_reg_power = chan->max_power = chan->orig_mpwr =

  			(int) MBM_TO_DBM(power_rule->max_eirp);

  
  		if (chan->flags & IEEE80211_CHAN_RADAR) {
  			chan->dfs_cac_ms = IEEE80211_DFS_MIN_CAC_TIME_MS;
  			if (reg_rule->dfs_cac_ms)
  				chan->dfs_cac_ms = reg_rule->dfs_cac_ms;
  		}

  		return;
  	}

  	chan->dfs_state = NL80211_DFS_USABLE;
  	chan->dfs_state_entered = jiffies;

  	chan->beacon_found = false;

  	chan->flags = flags | bw_flags | map_regdom_flags(reg_rule->flags);

  	chan->max_antenna_gain =
  		min_t(int, chan->orig_mag,
  		      MBI_TO_DBI(power_rule->max_antenna_gain));

  	chan->max_reg_power = (int) MBM_TO_DBM(power_rule->max_eirp);

  
  	if (chan->flags & IEEE80211_CHAN_RADAR) {
  		if (reg_rule->dfs_cac_ms)
  			chan->dfs_cac_ms = reg_rule->dfs_cac_ms;
  		else
  			chan->dfs_cac_ms = IEEE80211_DFS_MIN_CAC_TIME_MS;
  	}

  	if (chan->orig_mpwr) {
  		/*

  		 * Devices that use REGULATORY_COUNTRY_IE_FOLLOW_POWER
  		 * will always follow the passed country IE power settings.

  		 */
  		if (initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&

  		    wiphy->regulatory_flags & REGULATORY_COUNTRY_IE_FOLLOW_POWER)

  			chan->max_power = chan->max_reg_power;
  		else
  			chan->max_power = min(chan->orig_mpwr,
  					      chan->max_reg_power);
  	} else
  		chan->max_power = chan->max_reg_power;

  }

  static void handle_band(struct wiphy *wiphy,

  			enum nl80211_reg_initiator initiator,
  			struct ieee80211_supported_band *sband)

  {

  	unsigned int i;

  	if (!sband)
  		return;

  
  	for (i = 0; i < sband->n_channels; i++)

  		handle_channel(wiphy, initiator, &sband->channels[i]);

  }

  static bool reg_request_cell_base(struct regulatory_request *request)
  {
  	if (request->initiator != NL80211_REGDOM_SET_BY_USER)
  		return false;

  	return request->user_reg_hint_type == NL80211_USER_REG_HINT_CELL_BASE;

  }

  static bool reg_request_indoor(struct regulatory_request *request)
  {
  	if (request->initiator != NL80211_REGDOM_SET_BY_USER)
  		return false;
  	return request->user_reg_hint_type == NL80211_USER_REG_HINT_INDOOR;
  }

  bool reg_last_request_cell_base(void)
  {

  	return reg_request_cell_base(get_last_request());

  }

  #ifdef CONFIG_CFG80211_REG_CELLULAR_HINTS

  /* Core specific check */

  static enum reg_request_treatment
  reg_ignore_cell_hint(struct regulatory_request *pending_request)

  {

  	struct regulatory_request *lr = get_last_request();

  	if (!reg_num_devs_support_basehint)

  		return REG_REQ_IGNORE;

  	if (reg_request_cell_base(lr) &&

  	    !regdom_changes(pending_request->alpha2))

  		return REG_REQ_ALREADY_SET;

  	return REG_REQ_OK;

  }
  
  /* Device specific check */
  static bool reg_dev_ignore_cell_hint(struct wiphy *wiphy)
  {

  	return !(wiphy->features & NL80211_FEATURE_CELL_BASE_REG_HINTS);

  }
  #else
  static int reg_ignore_cell_hint(struct regulatory_request *pending_request)
  {

  	return REG_REQ_IGNORE;

  }

  
  static bool reg_dev_ignore_cell_hint(struct wiphy *wiphy)

  {
  	return true;
  }
  #endif

  static bool wiphy_strict_alpha2_regd(struct wiphy *wiphy)
  {

  	if (wiphy->regulatory_flags & REGULATORY_STRICT_REG &&
  	    !(wiphy->regulatory_flags & REGULATORY_CUSTOM_REG))

  		return true;
  	return false;
  }

  static bool ignore_reg_update(struct wiphy *wiphy,
  			      enum nl80211_reg_initiator initiator)

  {

  	struct regulatory_request *lr = get_last_request();
  
  	if (!lr) {

  		REG_DBG_PRINT("Ignoring regulatory request set by %s "
  			      "since last_request is not set
  ",

  			      reg_initiator_name(initiator));

  		return true;

  	}

  	if (initiator == NL80211_REGDOM_SET_BY_CORE &&

  	    wiphy->regulatory_flags & REGULATORY_CUSTOM_REG) {

  		REG_DBG_PRINT("Ignoring regulatory request set by %s "
  			      "since the driver uses its own custom "
  			      "regulatory domain
  ",

  			      reg_initiator_name(initiator));

  		return true;

  	}

  	/*
  	 * wiphy->regd will be set once the device has its own
  	 * desired regulatory domain set
  	 */

  	if (wiphy_strict_alpha2_regd(wiphy) && !wiphy->regd &&

  	    initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&

  	    !is_world_regdom(lr->alpha2)) {

  		REG_DBG_PRINT("Ignoring regulatory request set by %s "
  			      "since the driver requires its own regulatory "
  			      "domain to be set first
  ",

  			      reg_initiator_name(initiator));

  		return true;

  	}

  	if (reg_request_cell_base(lr))

  		return reg_dev_ignore_cell_hint(wiphy);

  	return false;
  }

  static bool reg_is_world_roaming(struct wiphy *wiphy)
  {
  	const struct ieee80211_regdomain *cr = get_cfg80211_regdom();
  	const struct ieee80211_regdomain *wr = get_wiphy_regdom(wiphy);
  	struct regulatory_request *lr = get_last_request();
  
  	if (is_world_regdom(cr->alpha2) || (wr && is_world_regdom(wr->alpha2)))
  		return true;
  
  	if (lr && lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&

  	    wiphy->regulatory_flags & REGULATORY_CUSTOM_REG)

  		return true;
  
  	return false;
  }

  static void handle_reg_beacon(struct wiphy *wiphy, unsigned int chan_idx,

  			      struct reg_beacon *reg_beacon)
  {

  	struct ieee80211_supported_band *sband;
  	struct ieee80211_channel *chan;

  	bool channel_changed = false;
  	struct ieee80211_channel chan_before;

  	sband = wiphy->bands[reg_beacon->chan.band];
  	chan = &sband->channels[chan_idx];
  
  	if (likely(chan->center_freq != reg_beacon->chan.center_freq))
  		return;

  	if (chan->beacon_found)
  		return;
  
  	chan->beacon_found = true;

  	if (!reg_is_world_roaming(wiphy))
  		return;

  	if (wiphy->regulatory_flags & REGULATORY_DISABLE_BEACON_HINTS)

  		return;

  	chan_before.center_freq = chan->center_freq;
  	chan_before.flags = chan->flags;

  	if (chan->flags & IEEE80211_CHAN_NO_IR) {
  		chan->flags &= ~IEEE80211_CHAN_NO_IR;

  		channel_changed = true;

  	}

  	if (channel_changed)
  		nl80211_send_beacon_hint_event(wiphy, &chan_before, chan);

  }
  
  /*
   * Called when a scan on a wiphy finds a beacon on
   * new channel
   */
  static void wiphy_update_new_beacon(struct wiphy *wiphy,
  				    struct reg_beacon *reg_beacon)
  {
  	unsigned int i;
  	struct ieee80211_supported_band *sband;

  	if (!wiphy->bands[reg_beacon->chan.band])
  		return;
  
  	sband = wiphy->bands[reg_beacon->chan.band];
  
  	for (i = 0; i < sband->n_channels; i++)
  		handle_reg_beacon(wiphy, i, reg_beacon);
  }
  
  /*
   * Called upon reg changes or a new wiphy is added
   */
  static void wiphy_update_beacon_reg(struct wiphy *wiphy)
  {
  	unsigned int i;
  	struct ieee80211_supported_band *sband;
  	struct reg_beacon *reg_beacon;

  	list_for_each_entry(reg_beacon, &reg_beacon_list, list) {
  		if (!wiphy->bands[reg_beacon->chan.band])
  			continue;
  		sband = wiphy->bands[reg_beacon->chan.band];
  		for (i = 0; i < sband->n_channels; i++)
  			handle_reg_beacon(wiphy, i, reg_beacon);
  	}
  }

  /* Reap the advantages of previously found beacons */
  static void reg_process_beacons(struct wiphy *wiphy)
  {

  	/*
  	 * Means we are just firing up cfg80211, so no beacons would
  	 * have been processed yet.
  	 */
  	if (!last_request)
  		return;

  	wiphy_update_beacon_reg(wiphy);
  }

  static bool is_ht40_allowed(struct ieee80211_channel *chan)

  {
  	if (!chan)

  		return false;

  	if (chan->flags & IEEE80211_CHAN_DISABLED)

  		return false;

  	/* This would happen when regulatory rules disallow HT40 completely */

  	if ((chan->flags & IEEE80211_CHAN_NO_HT40) == IEEE80211_CHAN_NO_HT40)
  		return false;
  	return true;

  }
  
  static void reg_process_ht_flags_channel(struct wiphy *wiphy,

  					 struct ieee80211_channel *channel)

  {

  	struct ieee80211_supported_band *sband = wiphy->bands[channel->band];

  	struct ieee80211_channel *channel_before = NULL, *channel_after = NULL;
  	unsigned int i;

  	if (!is_ht40_allowed(channel)) {

  		channel->flags |= IEEE80211_CHAN_NO_HT40;
  		return;
  	}
  
  	/*
  	 * We need to ensure the extension channels exist to
  	 * be able to use HT40- or HT40+, this finds them (or not)
  	 */
  	for (i = 0; i < sband->n_channels; i++) {
  		struct ieee80211_channel *c = &sband->channels[i];

  		if (c->center_freq == (channel->center_freq - 20))
  			channel_before = c;
  		if (c->center_freq == (channel->center_freq + 20))
  			channel_after = c;
  	}
  
  	/*
  	 * Please note that this assumes target bandwidth is 20 MHz,
  	 * if that ever changes we also need to change the below logic
  	 * to include that as well.
  	 */

  	if (!is_ht40_allowed(channel_before))

  		channel->flags |= IEEE80211_CHAN_NO_HT40MINUS;

  	else

  		channel->flags &= ~IEEE80211_CHAN_NO_HT40MINUS;

  	if (!is_ht40_allowed(channel_after))

  		channel->flags |= IEEE80211_CHAN_NO_HT40PLUS;

  	else

  		channel->flags &= ~IEEE80211_CHAN_NO_HT40PLUS;

  }
  
  static void reg_process_ht_flags_band(struct wiphy *wiphy,

  				      struct ieee80211_supported_band *sband)

  {
  	unsigned int i;

  	if (!sband)
  		return;

  
  	for (i = 0; i < sband->n_channels; i++)

  		reg_process_ht_flags_channel(wiphy, &sband->channels[i]);

  }
  
  static void reg_process_ht_flags(struct wiphy *wiphy)
  {
  	enum ieee80211_band band;
  
  	if (!wiphy)
  		return;

  	for (band = 0; band < IEEE80211_NUM_BANDS; band++)
  		reg_process_ht_flags_band(wiphy, wiphy->bands[band]);

  }

  static void reg_call_notifier(struct wiphy *wiphy,
  			      struct regulatory_request *request)
  {
  	if (wiphy->reg_notifier)
  		wiphy->reg_notifier(wiphy, request);
  }

  static void wiphy_update_regulatory(struct wiphy *wiphy,
  				    enum nl80211_reg_initiator initiator)

  {
  	enum ieee80211_band band;

  	struct regulatory_request *lr = get_last_request();

  	if (ignore_reg_update(wiphy, initiator)) {
  		/*
  		 * Regulatory updates set by CORE are ignored for custom
  		 * regulatory cards. Let us notify the changes to the driver,
  		 * as some drivers used this to restore its orig_* reg domain.
  		 */
  		if (initiator == NL80211_REGDOM_SET_BY_CORE &&

  		    wiphy->regulatory_flags & REGULATORY_CUSTOM_REG)

  			reg_call_notifier(wiphy, lr);

  		return;

  	}

  	lr->dfs_region = get_cfg80211_regdom()->dfs_region;

  	for (band = 0; band < IEEE80211_NUM_BANDS; band++)
  		handle_band(wiphy, initiator, wiphy->bands[band]);

  	reg_process_beacons(wiphy);

  	reg_process_ht_flags(wiphy);

  	reg_call_notifier(wiphy, lr);

  }

  static void update_all_wiphy_regulatory(enum nl80211_reg_initiator initiator)
  {
  	struct cfg80211_registered_device *rdev;

  	struct wiphy *wiphy;

  	ASSERT_RTNL();

  	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
  		wiphy = &rdev->wiphy;
  		wiphy_update_regulatory(wiphy, initiator);

  	}

  }

  static void handle_channel_custom(struct wiphy *wiphy,

  				  struct ieee80211_channel *chan,

  				  const struct ieee80211_regdomain *regd)
  {

  	u32 bw_flags = 0;

  	const struct ieee80211_reg_rule *reg_rule = NULL;
  	const struct ieee80211_power_rule *power_rule = NULL;

  	const struct ieee80211_freq_range *freq_range = NULL;

  	u32 max_bandwidth_khz;

  	reg_rule = freq_reg_info_regd(wiphy, MHZ_TO_KHZ(chan->center_freq),
  				      regd);

  	if (IS_ERR(reg_rule)) {

  		REG_DBG_PRINT("Disabling freq %d MHz as custom regd has no rule that fits it
  ",
  			      chan->center_freq);

  		chan->orig_flags |= IEEE80211_CHAN_DISABLED;
  		chan->flags = chan->orig_flags;

  		return;
  	}

  	chan_reg_rule_print_dbg(regd, chan, reg_rule);

  	power_rule = &reg_rule->power_rule;

  	freq_range = &reg_rule->freq_range;

  	max_bandwidth_khz = freq_range->max_bandwidth_khz;
  	/* Check if auto calculation requested */

  	if (reg_rule->flags & NL80211_RRF_AUTO_BW)

  		max_bandwidth_khz = reg_get_max_bandwidth(regd, reg_rule);

  	if (max_bandwidth_khz < MHZ_TO_KHZ(10))
  		bw_flags = IEEE80211_CHAN_NO_10MHZ;
  	if (max_bandwidth_khz < MHZ_TO_KHZ(20))
  		bw_flags |= IEEE80211_CHAN_NO_20MHZ;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(40))

  		bw_flags |= IEEE80211_CHAN_NO_HT40;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(80))

  		bw_flags |= IEEE80211_CHAN_NO_80MHZ;

  	if (max_bandwidth_khz < MHZ_TO_KHZ(160))

  		bw_flags |= IEEE80211_CHAN_NO_160MHZ;

  	chan->flags |= map_regdom_flags(reg_rule->flags) | bw_flags;

  	chan->max_antenna_gain = (int) MBI_TO_DBI(power_rule->max_antenna_gain);

  	chan->max_reg_power = chan->max_power =
  		(int) MBM_TO_DBM(power_rule->max_eirp);

  }

  static void handle_band_custom(struct wiphy *wiphy,
  			       struct ieee80211_supported_band *sband,

  			       const struct ieee80211_regdomain *regd)
  {
  	unsigned int i;

  	if (!sband)
  		return;

  
  	for (i = 0; i < sband->n_channels; i++)

  		handle_channel_custom(wiphy, &sband->channels[i], regd);

  }
  
  /* Used by drivers prior to wiphy registration */
  void wiphy_apply_custom_regulatory(struct wiphy *wiphy,
  				   const struct ieee80211_regdomain *regd)
  {
  	enum ieee80211_band band;

  	unsigned int bands_set = 0;

  	WARN(!(wiphy->regulatory_flags & REGULATORY_CUSTOM_REG),
  	     "wiphy should have REGULATORY_CUSTOM_REG
  ");
  	wiphy->regulatory_flags |= REGULATORY_CUSTOM_REG;

  	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {

  		if (!wiphy->bands[band])
  			continue;