cfg80211: Add an attribute to set inactivity timeout in AP mode

This patch adds an attribute, NL80211_ATTR_INACTIVITY_TIMEOUT,
to set the inactivity timeout which can be used to remove the
station in AP mode. This can be passed in NL80211_CMD_START_AP
and used by the drivers which have AP MLME in firmware but
don't support get_station() properly. To disable inactivity
timer in userspace, wpa_s for example, there is a new flag,
NL80211_FEATURE_INACTIVITY_TIMER, in nl80211_feature_flags
through which drivers can register their capability to use
the inactivity timeout to free the stations.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/nl80211.c

@@ -204,6 +204,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 		.len = NL80211_HT_CAPABILITY_LEN
 	},
 	[NL80211_ATTR_NOACK_MAP] = { .type = NLA_U16 },
+	[NL80211_ATTR_INACTIVITY_TIMEOUT] = { .type = NLA_U16 },
 };
 
 /* policy for the key attributes */
@@ -2214,6 +2215,13 @@ static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		return err;
 
+	if (info->attrs[NL80211_ATTR_INACTIVITY_TIMEOUT]) {
+		if (!(rdev->wiphy.features & NL80211_FEATURE_INACTIVITY_TIMER))
+			return -EOPNOTSUPP;
+		params.inactivity_timeout = nla_get_u16(
+			info->attrs[NL80211_ATTR_INACTIVITY_TIMEOUT]);
+	}
+
 	err = rdev->ops->start_ap(&rdev->wiphy, dev, &params);
 	if (!err)
 		wdev->beacon_interval = params.beacon_interval;