nl80211: advertise HT/VHT channel limitations

When drivers or regulatory have limitations on
40, 80 or 160 MHz channels, advertise these to
userspace via nl80211. Also add a new feature
flag to let userspace know this is supported.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 31 insertions, 1 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 90b7af86f392..3880f6ad7ed1 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2041,6 +2041,16 @@ enum nl80211_band_attr {
  *      (enum nl80211_dfs_state)
  * @NL80211_FREQUENCY_ATTR_DFS_TIME: time in miliseconds for how long
  *      this channel is in this DFS state.
+ * @NL80211_FREQUENCY_ATTR_NO_HT40_MINUS: HT40- isn't possible with this
+ *      channel as the control channel
+ * @NL80211_FREQUENCY_ATTR_NO_HT40_PLUS: HT40+ isn't possible with this
+ *      channel as the control channel
+ * @NL80211_FREQUENCY_ATTR_NO_80MHZ: any 80 MHz channel using this channel
+ *      as the primary or any of the secondary channels isn't possible,
+ *      this includes 80+80 channels
+ * @NL80211_FREQUENCY_ATTR_NO_160MHZ: any 160 MHz (but not 80+80) channel
+ *      using this channel as the primary or any of the secondary channels
+ *      isn't possible
  * @NL80211_FREQUENCY_ATTR_MAX: highest frequency attribute number
  *      currently defined
  * @__NL80211_FREQUENCY_ATTR_AFTER_LAST: internal use
@@ -2055,6 +2065,10 @@ enum nl80211_frequency_attr {
         NL80211_FREQUENCY_ATTR_MAX_TX_POWER,
         NL80211_FREQUENCY_ATTR_DFS_STATE,
         NL80211_FREQUENCY_ATTR_DFS_TIME,
+        NL80211_FREQUENCY_ATTR_NO_HT40_MINUS,
+        NL80211_FREQUENCY_ATTR_NO_HT40_PLUS,
+        NL80211_FREQUENCY_ATTR_NO_80MHZ,
+        NL80211_FREQUENCY_ATTR_NO_160MHZ,
 
         /* keep last */
         __NL80211_FREQUENCY_ATTR_AFTER_LAST,
@@ -3421,6 +3435,8 @@ enum nl80211_ap_sme_features {
  *      Note that even for drivers that support this, the default is to add
  *      stations in authenticated/associated state, so to add unauthenticated
  *      stations the authenticated/associated bits have to be set in the mask.
+ * @NL80211_FEATURE_ADVERTISE_CHAN_LIMITS: cfg80211 advertises channel limits
+ *      (HT40, VHT 80/160 MHz) if this flag is set
  */
 enum nl80211_feature_flags {
         NL80211_FEATURE_SK_TX_STATUS                    = 1 << 0,
@@ -3437,6 +3453,7 @@ enum nl80211_feature_flags {
         NL80211_FEATURE_P2P_GO_CTWIN                    = 1 << 11,
         NL80211_FEATURE_P2P_GO_OPPPS                    = 1 << 12,
         NL80211_FEATURE_FULL_AP_CLIENT_STATE            = 1 << 13,
+        NL80211_FEATURE_ADVERTISE_CHAN_LIMITS           = 1 << 14,
 };
 
 /**
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 922002105062..33b75b9b8efa 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -367,7 +367,8 @@ struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv)
         rdev->wiphy.rts_threshold = (u32) -1;
         rdev->wiphy.coverage_class = 0;
 
-        rdev->wiphy.features = NL80211_FEATURE_SCAN_FLUSH;
+        rdev->wiphy.features = NL80211_FEATURE_SCAN_FLUSH |
+                               NL80211_FEATURE_ADVERTISE_CHAN_LIMITS;
 
         return &rdev->wiphy;
 }
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index c1e18ccf4049..7e40b9e82b45 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -562,6 +562,18 @@ static int nl80211_msg_put_channel(struct sk_buff *msg,
                 if (nla_put_u32(msg, NL80211_FREQUENCY_ATTR_DFS_TIME, time))
                         goto nla_put_failure;
         }
+        if ((chan->flags & IEEE80211_CHAN_NO_HT40MINUS) &&
+            nla_put_flag(msg, NL80211_FREQUENCY_ATTR_NO_HT40_MINUS))
+                goto nla_put_failure;
+        if ((chan->flags & IEEE80211_CHAN_NO_HT40PLUS) &&
+            nla_put_flag(msg, NL80211_FREQUENCY_ATTR_NO_HT40_PLUS))
+                goto nla_put_failure;
+        if ((chan->flags & IEEE80211_CHAN_NO_80MHZ) &&
+            nla_put_flag(msg, NL80211_FREQUENCY_ATTR_NO_80MHZ))
+                goto nla_put_failure;
+        if ((chan->flags & IEEE80211_CHAN_NO_160MHZ) &&
+            nla_put_flag(msg, NL80211_FREQUENCY_ATTR_NO_160MHZ))
+                goto nla_put_failure;
 
         if (nla_put_u32(msg, NL80211_FREQUENCY_ATTR_MAX_TX_POWER,
                         DBM_TO_MBM(chan->max_power)))