RFC add offchannel monitor chain support

Introduce the capability to configure a dedicated chain available for radar detection on some hw (e.g. mt7915). The driver is supposed to implement CAC management in sw or fw while hostapd (or iw) will implement the logic to select and configure the monitored channel.
Using a dedicated chain to perform the CAC, the AP can avoid the CAC downtime switching to a new DFS channel.

Lorenzo Bianconi (7):
mac80211: introduce set_offchan_chain callback
cfg80211: introduce nl80211_set_offchan_chain callback
cfg80211: introduce cfg80211_cac_offchan_event routine
mt76: mt7915: introduce mt7915_set_offchan_chain routine
mt76: mt7915: enable radar trigger on rdd2
mt76: mt7915: introduce rdd_monitor debugfs node
mt76: mt7915: add cac support for offchannel chain

 .../wireless/mediatek/mt76/mt7915/debugfs.c   | 37 +++++++++-
 .../net/wireless/mediatek/mt76/mt7915/init.c  |  4 ++
 .../net/wireless/mediatek/mt76/mt7915/mac.c   | 57 ++++++++++++++++
 .../net/wireless/mediatek/mt76/mt7915/main.c  | 33 +++++++++
 .../net/wireless/mediatek/mt76/mt7915/mcu.c   | 67 ++++++++++++++++++-
 .../net/wireless/mediatek/mt76/mt7915/mcu.h   | 24 +++++++
 .../wireless/mediatek/mt76/mt7915/mt7915.h    | 10 +++
 include/net/cfg80211.h                        | 19 ++++++
 include/net/mac80211.h                        |  5 ++
 include/uapi/linux/nl80211.h                  |  6 ++
 net/mac80211/cfg.c                            | 13 ++++
 net/wireless/mlme.c                           | 26 +++++++
 net/wireless/nl80211.c                        | 41 ++++++++++++
 net/wireless/rdev-ops.h                       | 17 +++++
 net/wireless/trace.h                          | 19 ++++++
 15 files changed, 375 insertions(+), 3 deletions(-)

2.31.1