mac80211: add channel switch command and beacon callbacks

The count field in CSA must be decremented with each beacon
transmitted. This patch implements the functionality for drivers
using ieee80211_beacon_get(). Other drivers must call back manually
after reaching count == 0.

This patch also contains the handling and finish worker for the channel
switch command, and mac80211/chanctx code to allow to change a channel
definition of an active channel context.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
[small cleanups, catch identical chandef]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index f65873f..0e42322 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2338,6 +2338,81 @@ static int ieee80211_beacon_add_tim(struct ieee80211_sub_if_data *sdata,
 	return 0;
 }
 
+void ieee80211_csa_finish(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+
+	ieee80211_queue_work(&sdata->local->hw,
+			     &sdata->csa_finalize_work);
+}
+EXPORT_SYMBOL(ieee80211_csa_finish);
+
+static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
+				 struct beacon_data *beacon)
+{
+	struct probe_resp *resp;
+	int counter_offset_beacon = sdata->csa_counter_offset_beacon;
+	int counter_offset_presp = sdata->csa_counter_offset_presp;
+
+	/* warn if the driver did not check for/react to csa completeness */
+	if (WARN_ON(((u8 *)beacon->tail)[counter_offset_beacon] == 0))
+		return;
+
+	((u8 *)beacon->tail)[counter_offset_beacon]--;
+
+	if (sdata->vif.type == NL80211_IFTYPE_AP &&
+	    counter_offset_presp) {
+		rcu_read_lock();
+		resp = rcu_dereference(sdata->u.ap.probe_resp);
+
+		/* if nl80211 accepted the offset, this should not happen. */
+		if (WARN_ON(!resp)) {
+			rcu_read_unlock();
+			return;
+		}
+		resp->data[counter_offset_presp]--;
+		rcu_read_unlock();
+	}
+}
+
+bool ieee80211_csa_is_complete(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+	struct beacon_data *beacon = NULL;
+	u8 *beacon_data;
+	size_t beacon_data_len;
+	int counter_beacon = sdata->csa_counter_offset_beacon;
+	int ret = false;
+
+	if (!ieee80211_sdata_running(sdata))
+		return false;
+
+	rcu_read_lock();
+	if (vif->type == NL80211_IFTYPE_AP) {
+		struct ieee80211_if_ap *ap = &sdata->u.ap;
+
+		beacon = rcu_dereference(ap->beacon);
+		if (WARN_ON(!beacon || !beacon->tail))
+			goto out;
+		beacon_data = beacon->tail;
+		beacon_data_len = beacon->tail_len;
+	} else {
+		WARN_ON(1);
+		goto out;
+	}
+
+	if (WARN_ON(counter_beacon > beacon_data_len))
+		goto out;
+
+	if (beacon_data[counter_beacon] == 0)
+		ret = true;
+ out:
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_csa_is_complete);
+
 struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 					 struct ieee80211_vif *vif,
 					 u16 *tim_offset, u16 *tim_length)
@@ -2368,6 +2443,9 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 		struct beacon_data *beacon = rcu_dereference(ap->beacon);
 
 		if (beacon) {
+			if (sdata->vif.csa_active)
+				ieee80211_update_csa(sdata, beacon);
+
 			/*
 			 * headroom, head length,
 			 * tail length and maximum TIM length