Prefer 6 GHz APs for connection in BSS selection

Prefer 6 GHz APs when estimated throughputs are equal with APs from the
2.4/5 GHz bands while selecting APs for connection. Also add a 6 GHz
specific noise floor default value for the 6 GHz band (with the same
value as was used for 5 GHz previously) to make this step clearer.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

wpa_supplicant/scan.c

@@ -2047,6 +2047,8 @@ static int wpa_scan_result_compar(const void *a, const void *b)
 	}
 	if ((snr_a && snr_b && abs(snr_b - snr_a) < 5) ||
 	    (wa->qual && wb->qual && abs(wb->qual - wa->qual) < 10)) {
+		if (is_6ghz_freq(wa->freq) ^ is_6ghz_freq(wb->freq))
+			return is_6ghz_freq(wa->freq) ? -1 : 1;
 		if (IS_5GHZ(wa->freq) ^ IS_5GHZ(wb->freq))
 			return IS_5GHZ(wa->freq) ? -1 : 1;
 	}
@@ -2207,9 +2209,10 @@ void filter_scan_res(struct wpa_supplicant *wpa_s,
 void scan_snr(struct wpa_scan_res *res)
 {
 	if (res->flags & WPA_SCAN_NOISE_INVALID) {
-		res->noise = IS_5GHZ(res->freq) ?
-			DEFAULT_NOISE_FLOOR_5GHZ :
-			DEFAULT_NOISE_FLOOR_2GHZ;
+		res->noise = is_6ghz_freq(res->freq) ?
+			DEFAULT_NOISE_FLOOR_6GHZ :
+			(IS_5GHZ(res->freq) ?
+			 DEFAULT_NOISE_FLOOR_5GHZ : DEFAULT_NOISE_FLOOR_2GHZ);
 	}
 
 	if (res->flags & WPA_SCAN_LEVEL_DBM) {

wpa_supplicant/scan.h

@@ -16,6 +16,7 @@
  */
 #define DEFAULT_NOISE_FLOOR_2GHZ (-89)
 #define DEFAULT_NOISE_FLOOR_5GHZ (-92)
+#define DEFAULT_NOISE_FLOOR_6GHZ (-92)
 
 /*
  * Channels with a great SNR can operate at full rate. What is a great SNR?
@@ -30,7 +31,7 @@
 #define GREAT_SNR 25
 
 #define IS_2P4GHZ(n) (n >= 2412 && n <= 2484)
-#define IS_5GHZ(n) (n > 4000)
+#define IS_5GHZ(n) (n > 4000 && n < 5895)
 
 int wpa_supplicant_enabled_networks(struct wpa_supplicant *wpa_s);
 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec);