cfg80211: add channel switch started notification

Add a new NL80211_CH_SWITCH_STARTED_NOTIFY message that can be sent to
the userspace when a channel switch process has started.  This allows
userspace to take action, for instance, by requesting other interfaces
to switch channel as necessary.

This patch introduces a function that allows the drivers to send this
notification.  It should be used when the driver starts processing a
channel switch initiated by a remote device (eg. when a STA receives a
CSA from the AP) and when it successfully starts a userspace-triggered
channel switch (eg. when hostapd triggers a channel swith in the AP).

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 9b3025e4377a..354163433352 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -645,6 +645,15 @@
  *      %NL80211_ATTR_IFINDEX is now on %NL80211_ATTR_WIPHY_FREQ and the
  *      attributes determining channel width.
  *
+ * @NL80211_CMD_CH_SWITCH_STARTED_NOTIFY: Notify that a channel switch
+ *      has been started on an interface, regardless of the initiator
+ *      (ie. whether it was requested from a remote device or
+ *      initiated on our own).  It indicates that
+ *      %NL80211_ATTR_IFINDEX will be on %NL80211_ATTR_WIPHY_FREQ
+ *      after %NL80211_ATTR_CH_SWITCH_COUNT TBTT's.  The userspace may
+ *      decide to react to this indication by requesting other
+ *      interfaces to change channel as well.
+ *
  * @NL80211_CMD_START_P2P_DEVICE: Start the given P2P Device, identified by
  *      its %NL80211_ATTR_WDEV identifier. It must have been created with
  *      %NL80211_CMD_NEW_INTERFACE previously. After it has been started, the
@@ -930,6 +939,8 @@ enum nl80211_commands {
         NL80211_CMD_JOIN_OCB,
         NL80211_CMD_LEAVE_OCB,
 
+        NL80211_CMD_CH_SWITCH_STARTED_NOTIFY,
+
         /* add new commands above here */
 
         /* used to define NL80211_CMD_MAX below */