mac80211: split off channel switch parsing function

The channel switch parsing function can be re-used for the IBSS code,
put the common part into an extra function.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
[also move/rename chandef_downgrade]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index d353c64..7f0e6da 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1480,6 +1480,29 @@
 void ieee80211_process_measurement_req(struct ieee80211_sub_if_data *sdata,
 				       struct ieee80211_mgmt *mgmt,
 				       size_t len);
+/**
+ * ieee80211_parse_ch_switch_ie - parses channel switch IEs
+ * @sdata: the sdata of the interface which has received the frame
+ * @elems: parsed 802.11 elements received with the frame
+ * @beacon: indicates if the frame was a beacon or probe response
+ * @current_band: indicates the current band
+ * @sta_flags: contains information about own capabilities and restrictions
+ *	to decide which channel switch announcements can be accepted. Only the
+ *	following subset of &enum ieee80211_sta_flags are evaluated:
+ *	%IEEE80211_STA_DISABLE_HT, %IEEE80211_STA_DISABLE_VHT,
+ *	%IEEE80211_STA_DISABLE_40MHZ, %IEEE80211_STA_DISABLE_80P80MHZ,
+ *	%IEEE80211_STA_DISABLE_160MHZ.
+ * @count: to be filled with the counter until the switch (on success only)
+ * @bssid: the currently connected bssid (for reporting)
+ * @mode: to be filled with CSA mode (on success only)
+ * @new_chandef: to be filled with destination chandef (on success only)
+ * Return: 0 on success, <0 on error and >0 if there is nothing to parse.
+ */
+int ieee80211_parse_ch_switch_ie(struct ieee80211_sub_if_data *sdata,
+				 struct ieee802_11_elems *elems, bool beacon,
+				 enum ieee80211_band current_band,
+				 u32 sta_flags, u8 *bssid, u8 *count, u8 *mode,
+				 struct cfg80211_chan_def *new_chandef);
 
 /* Suspend/resume and hw reconfiguration */
 int ieee80211_reconfig(struct ieee80211_local *local);
@@ -1653,6 +1676,7 @@
 void ieee80211_ht_oper_to_chandef(struct ieee80211_channel *control_chan,
 				  const struct ieee80211_ht_operation *ht_oper,
 				  struct cfg80211_chan_def *chandef);
+u32 ieee80211_chandef_downgrade(struct cfg80211_chan_def *c);
 
 int __must_check
 ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,