nl80211: specify RSSI threshold in scheduled scan

Support configuring an RSSI threshold in dBm (s32) when requesting
scheduled scan, below which a BSS won't be reported by the cfg80211
driver.
Signed-off-by: Thomas Pedersen <c_tpeder@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/nl80211.h

@@ -1542,6 +1542,9 @@ enum nl80211_attrs {
 
 #define NL80211_MIN_REMAIN_ON_CHANNEL_TIME	10
 
+/* default RSSI threshold for scan results if none specified. */
+#define NL80211_SCAN_RSSI_THOLD_OFF		-300
+
 /**
  * enum nl80211_iftype - (virtual) interface types
  *
@@ -1974,6 +1977,8 @@ enum nl80211_reg_rule_attr {
  * @__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID: attribute number 0 is reserved
  * @NL80211_SCHED_SCAN_MATCH_ATTR_SSID: SSID to be used for matching,
  * only report BSS with matching SSID.
+ * @NL80211_SCHED_SCAN_MATCH_ATTR_RSSI: RSSI threshold (in dBm) for reporting a
+ *	BSS in scan results. Filtering is turned off if not specified.
  * @NL80211_SCHED_SCAN_MATCH_ATTR_MAX: highest scheduled scan filter
  *	attribute number currently defined
  * @__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST: internal use
@@ -1982,6 +1987,7 @@ enum nl80211_sched_scan_match_attr {
 	__NL80211_SCHED_SCAN_MATCH_ATTR_INVALID,
 
 	NL80211_SCHED_SCAN_MATCH_ATTR_SSID,
+	NL80211_SCHED_SCAN_MATCH_ATTR_RSSI,
 
 	/* keep last */
 	__NL80211_SCHED_SCAN_MATCH_ATTR_AFTER_LAST,

include/net/cfg80211.h

@@ -1027,6 +1027,7 @@ struct cfg80211_match_set {
  * @wiphy: the wiphy this was for
  * @dev: the interface
  * @channels: channels to scan
+ * @rssi_thold: don't report scan results below this threshold (in s32 dBm)
  */
 struct cfg80211_sched_scan_request {
 	struct cfg80211_ssid *ssids;
@@ -1037,6 +1038,7 @@ struct cfg80211_sched_scan_request {
 	size_t ie_len;
 	struct cfg80211_match_set *match_sets;
 	int n_match_sets;
+	s32 rssi_thold;
 
 	/* internal */
 	struct wiphy *wiphy;

net/wireless/nl80211.c

@@ -340,6 +340,7 @@ static const struct nla_policy
 nl80211_match_policy[NL80211_SCHED_SCAN_MATCH_ATTR_MAX + 1] = {
 	[NL80211_SCHED_SCAN_MATCH_ATTR_SSID] = { .type = NLA_BINARY,
 						 .len = IEEE80211_MAX_SSID_LEN },
+	[NL80211_SCHED_SCAN_MATCH_ATTR_RSSI] = { .type = NLA_U32 },
 };
 
 /* ifidx get helper */
@@ -4387,7 +4388,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 		nla_for_each_nested(attr,
 				    info->attrs[NL80211_ATTR_SCHED_SCAN_MATCH],
 				    tmp) {
-			struct nlattr *ssid;
+			struct nlattr *ssid, *rssi;
 
 			nla_parse(tb, NL80211_SCHED_SCAN_MATCH_ATTR_MAX,
 				  nla_data(attr), nla_len(attr),
@@ -4403,6 +4404,12 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 				request->match_sets[i].ssid.ssid_len =
 					nla_len(ssid);
 			}
+			rssi = tb[NL80211_SCHED_SCAN_MATCH_ATTR_RSSI];
+			if (rssi)
+				request->rssi_thold = nla_get_u32(rssi);
+			else
+				request->rssi_thold =
+						   NL80211_SCAN_RSSI_THOLD_OFF;
 			i++;
 		}
 	}