mac80211: introduce channel context skeleton code

Channel context are the foundation for multi-channel
operation. They are are immutable and are re-created
(or re-used if other interfaces are bound to a certain
channel and a compatible channel type) on channel
switching.

This is an initial implementation and more features
will come in separate patches.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
[some changes including RCU protection]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 82558c8decf8..ab1b5bafb568 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -144,6 +144,32 @@ struct ieee80211_low_level_stats {
 };
 
 /**
+ * enum ieee80211_chanctx_change - change flag for channel context
+ * @IEEE80211_CHANCTX_CHANGE_CHANNEL_TYPE: The channel type was changed
+ */
+enum ieee80211_chanctx_change {
+	IEEE80211_CHANCTX_CHANGE_CHANNEL_TYPE	= BIT(0),
+};
+
+/**
+ * struct ieee80211_chanctx_conf - channel context that vifs may be tuned to
+ *
+ * This is the driver-visible part. The ieee80211_chanctx
+ * that contains it is visible in mac80211 only.
+ *
+ * @channel: the channel to tune to
+ * @channel_type: the channel (HT) type
+ * @drv_priv: data area for driver use, will always be aligned to
+ *	sizeof(void *), size is determined in hw information.
+ */
+struct ieee80211_chanctx_conf {
+	struct ieee80211_channel *channel;
+	enum nl80211_channel_type channel_type;
+
+	u8 drv_priv[0] __attribute__((__aligned__(sizeof(void *))));
+};
+
+/**
  * enum ieee80211_bss_change - BSS change notification flags
  *
  * These flags are used with the bss_info_changed() callback
@@ -931,6 +957,11 @@ enum ieee80211_vif_flags {
  *	at runtime, mac80211 will never touch this field
  * @hw_queue: hardware queue for each AC
  * @cab_queue: content-after-beacon (DTIM beacon really) queue, AP mode only
+ * @chanctx_conf: The channel context this interface is assigned to, or %NULL
+ *	when it is not assigned. This pointer is RCU-protected due to the TX
+ *	path needing to access it; even though the netdev carrier will always
+ *	be off when it is %NULL there can still be races and packets could be
+ *	processed after it switches back to %NULL.
  * @drv_priv: data area for driver use, will always be aligned to
  *	sizeof(void *).
  */
@@ -943,6 +974,8 @@ struct ieee80211_vif {
 	u8 cab_queue;
 	u8 hw_queue[IEEE80211_NUM_ACS];
 
+	struct ieee80211_chanctx_conf __rcu *chanctx_conf;
+
 	u32 driver_flags;
 
 	/* must be last */
@@ -1325,6 +1358,8 @@ enum ieee80211_hw_flags {
  *	within &struct ieee80211_vif.
  * @sta_data_size: size (in bytes) of the drv_priv data area
  *	within &struct ieee80211_sta.
+ * @chanctx_data_size: size (in bytes) of the drv_priv data area
+ *	within &struct ieee80211_chanctx_conf.
  *
  * @max_rates: maximum number of alternate rate retry stages the hw
  *	can handle.
@@ -1369,6 +1404,7 @@ struct ieee80211_hw {
 	int channel_change_time;
 	int vif_data_size;
 	int sta_data_size;
+	int chanctx_data_size;
 	int napi_weight;
 	u16 queues;
 	u16 max_listen_interval;