cfg80211: Advertise maximum associated STAs in AP mode

This allows drivers to advertise the maximum number of associated
stations they support in AP mode (including P2P GO). User space
applications can use this for cleaner way of handling the limit (e.g.,
hostapd rejecting IEEE 802.11 authentication without manual
configuration of the limit) or to figure out what type of use cases can
be executed with multiple devices before trying and failing.

Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index e57de3318068..9a86c8bf6da6 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -1568,6 +1568,13 @@ enum nl80211_commands {
  * @NL80211_ATTR_MAC_HINT: MAC address recommendation as initial BSS
  * @NL80211_ATTR_WIPHY_FREQ_HINT: frequency of the recommended initial BSS
  *
+ * @NL80211_ATTR_MAX_AP_ASSOC_STA: Device attribute that indicates how many
+ *      associated stations are supported in AP mode (including P2P GO); u32.
+ *      Since drivers may not have a fixed limit on the maximum number (e.g.,
+ *      other concurrent operations may affect this), drivers are allowed to
+ *      advertise values that cannot always be met. In such cases, an attempt
+ *      to add a new station entry with @NL80211_CMD_NEW_STATION may fail.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1899,6 +1906,8 @@ enum nl80211_attrs {
         NL80211_ATTR_MAC_HINT,
         NL80211_ATTR_WIPHY_FREQ_HINT,
 
+        NL80211_ATTR_MAX_AP_ASSOC_STA,
+
         /* add attributes here, update the policy in nl80211.c */
 
         __NL80211_ATTR_AFTER_LAST,