iwlwifi: move iwl_is_ht40_tx_allowed out of iwl-core.c

This is really something determined by
station parameters, so move it to
iwl-agn-sta.c.

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-sta.c b/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
index 79cbaab..42af9f9 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
@@ -170,6 +170,50 @@
 	return cmd.handler_status;
 }
 
+static bool iwl_is_channel_extension(struct iwl_priv *priv,
+				     enum ieee80211_band band,
+				     u16 channel, u8 extension_chan_offset)
+{
+	const struct iwl_channel_info *ch_info;
+
+	ch_info = iwl_get_channel_info(priv, band, channel);
+	if (!is_channel_valid(ch_info))
+		return false;
+
+	if (extension_chan_offset == IEEE80211_HT_PARAM_CHA_SEC_ABOVE)
+		return !(ch_info->ht40_extension_channel &
+					IEEE80211_CHAN_NO_HT40PLUS);
+	else if (extension_chan_offset == IEEE80211_HT_PARAM_CHA_SEC_BELOW)
+		return !(ch_info->ht40_extension_channel &
+					IEEE80211_CHAN_NO_HT40MINUS);
+
+	return false;
+}
+
+bool iwl_is_ht40_tx_allowed(struct iwl_priv *priv,
+			    struct iwl_rxon_context *ctx,
+			    struct ieee80211_sta_ht_cap *ht_cap)
+{
+	if (!ctx->ht.enabled || !ctx->ht.is_40mhz)
+		return false;
+
+	/*
+	 * We do not check for IEEE80211_HT_CAP_SUP_WIDTH_20_40
+	 * the bit will not set if it is pure 40MHz case
+	 */
+	if (ht_cap && !ht_cap->ht_supported)
+		return false;
+
+#ifdef CONFIG_IWLWIFI_DEBUGFS
+	if (priv->disable_ht40)
+		return false;
+#endif
+
+	return iwl_is_channel_extension(priv, priv->band,
+			le16_to_cpu(ctx->staging.channel),
+			ctx->ht.extension_chan_offset);
+}
+
 static void iwl_sta_calc_ht_flags(struct iwl_priv *priv,
 				  struct ieee80211_sta *sta,
 				  struct iwl_rxon_context *ctx,