cfg80211: DFS check chandef usable before CAC

Check chandef we get in CAC request is usable for CAC.
All channels have to be DFS channels. Allow DFS_USABLE
and DFS_AVAILABLE channels mix. At least one channel
has to be DFS_USABLE (require CAC).

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Reviewed-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/net/wireless/core.h b/net/wireless/core.h
index eb0f7a3a25a9..2888867ee7c5 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -382,6 +382,19 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
                                  enum cfg80211_chan_mode chanmode,
                                  u8 radar_detect);
 
+/**
+ * cfg80211_chandef_dfs_usable - checks if chandef is DFS usable
+ * @wiphy: the wiphy to validate against
+ * @chandef: the channel definition to check
+ *
+ * Checks if chandef is usable and we can/need start CAC on such channel.
+ *
+ * Return: Return true if all channels available and at least
+ *         one channel require CAC (NL80211_DFS_USABLE)
+ */
+bool cfg80211_chandef_dfs_usable(struct wiphy *wiphy,
+                                 const struct cfg80211_chan_def *chandef);
+
 void cfg80211_set_dfs_state(struct wiphy *wiphy,
                             const struct cfg80211_chan_def *chandef,
                             enum nl80211_dfs_state dfs_state);