mac80211: support direct offchannel TX offload

For devices supported by iwlwifi sometimes
off-channel transmissions need to be handled
by the device completely. To support this
mac80211 needs to pass the frame directly
to the driver and not through the TX path
as the driver needs the frame and channel
information at the same time.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

5 files changed, 108 insertions, 0 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 140503d..8b436c7 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1800,6 +1800,33 @@ static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct net_device *dev,
 
 	*cookie = (unsigned long) skb;
 
+	if (is_offchan && local->ops->offchannel_tx) {
+		int ret;
+
+		IEEE80211_SKB_CB(skb)->band = chan->band;
+
+		mutex_lock(&local->mtx);
+
+		if (local->hw_offchan_tx_cookie) {
+			mutex_unlock(&local->mtx);
+			return -EBUSY;
+		}
+
+		/* TODO: bitrate control, TX processing? */
+		ret = drv_offchannel_tx(local, skb, chan, channel_type, wait);
+
+		if (ret == 0)
+			local->hw_offchan_tx_cookie = *cookie;
+		mutex_unlock(&local->mtx);
+
+		/*
+		 * Allow driver to return 1 to indicate it wants to have the
+		 * frame transmitted with a remain_on_channel + regular TX.
+		 */
+		if (ret != 1)
+			return ret;
+	}
+
 	if (is_offchan && local->ops->remain_on_channel) {
 		unsigned int duration;
 		int ret;
@@ -1886,6 +1913,18 @@ static int ieee80211_mgmt_tx_cancel_wait(struct wiphy *wiphy,
 
 	mutex_lock(&local->mtx);
 
+	if (local->ops->offchannel_tx_cancel_wait &&
+	    local->hw_offchan_tx_cookie == cookie) {
+		ret = drv_offchannel_tx_cancel_wait(local);
+
+		if (!ret)
+			local->hw_offchan_tx_cookie = 0;
+
+		mutex_unlock(&local->mtx);
+
+		return ret;
+	}
+
 	if (local->ops->cancel_remain_on_channel) {
 		cookie ^= 2;
 		ret = ieee80211_cancel_remain_on_channel_hw(local, cookie);
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 32f05c1..3729296 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -495,4 +495,35 @@ static inline int drv_cancel_remain_on_channel(struct ieee80211_local *local)
 	return ret;
 }
 
+static inline int drv_offchannel_tx(struct ieee80211_local *local,
+				    struct sk_buff *skb,
+				    struct ieee80211_channel *chan,
+				    enum nl80211_channel_type channel_type,
+				    unsigned int wait)
+{
+	int ret;
+
+	might_sleep();
+
+	trace_drv_offchannel_tx(local, skb, chan, channel_type, wait);
+	ret = local->ops->offchannel_tx(&local->hw, skb, chan,
+					channel_type, wait);
+	trace_drv_return_int(local, ret);
+
+	return ret;
+}
+
+static inline int drv_offchannel_tx_cancel_wait(struct ieee80211_local *local)
+{
+	int ret;
+
+	might_sleep();
+
+	trace_drv_offchannel_tx_cancel_wait(local);
+	ret = local->ops->offchannel_tx_cancel_wait(&local->hw);
+	trace_drv_return_int(local, ret);
+
+	return ret;
+}
+
 #endif /* __MAC80211_DRIVER_OPS */
diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index e5cce19..520fe24 100644
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -884,6 +884,39 @@ DEFINE_EVENT(local_only_evt, drv_cancel_remain_on_channel,
 	TP_ARGS(local)
 );
 
+TRACE_EVENT(drv_offchannel_tx,
+	TP_PROTO(struct ieee80211_local *local, struct sk_buff *skb,
+		 struct ieee80211_channel *chan,
+		 enum nl80211_channel_type channel_type,
+		 unsigned int wait),
+
+	TP_ARGS(local, skb, chan, channel_type, wait),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		__field(int, center_freq)
+		__field(int, channel_type)
+		__field(unsigned int, wait)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		__entry->center_freq = chan->center_freq;
+		__entry->channel_type = channel_type;
+		__entry->wait = wait;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT " freq:%dMHz, wait:%dms",
+		LOCAL_PR_ARG, __entry->center_freq, __entry->wait
+	)
+);
+
+DEFINE_EVENT(local_only_evt, drv_offchannel_tx_cancel_wait,
+	TP_PROTO(struct ieee80211_local *local),
+	TP_ARGS(local)
+);
+
 /*
  * Tracing for API calls that drivers call.
  */
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0a570a1..a404017 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -957,6 +957,7 @@ struct ieee80211_local {
 	unsigned int hw_roc_duration;
 	u32 hw_roc_cookie;
 	bool hw_roc_for_tx;
+	unsigned long hw_offchan_tx_cookie;
 
 	/* dummy netdev for use w/ NAPI */
 	struct net_device napi_dev;
diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index 8651851..b936dd2 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -341,6 +341,10 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 			cookie = local->hw_roc_cookie ^ 2;
 			local->hw_roc_skb_for_status = NULL;
 		}
+
+		if (cookie == local->hw_offchan_tx_cookie)
+			local->hw_offchan_tx_cookie = 0;
+
 		cfg80211_mgmt_tx_status(
 			skb->dev, cookie, skb->data, skb->len,
 			!!(info->flags & IEEE80211_TX_STAT_ACK), GFP_ATOMIC);