Allow non-PCS 6 GHz channels to be excluded from ACS

Add support to exclude non-PSC 6 GHz channels from the input frequency
list to ACS. The new acs_exclude_6ghz_non_psc=1 parameter can be used by
6 GHz only APs.

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

hostapd/config_file.c

@@ -3169,6 +3169,8 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 			return 1;
 		}
 		conf->acs_freq_list_present = 1;
+	} else if (os_strcmp(buf, "acs_exclude_6ghz_non_psc") == 0) {
+		conf->acs_exclude_6ghz_non_psc = atoi(pos);
 	} else if (os_strcmp(buf, "beacon_int") == 0) {
 		int val = atoi(pos);
 		/* MIB defines range as 1..65535, but very small values

hostapd/hostapd.conf

@@ -218,6 +218,13 @@ channel=1
 # in cases where the driver supports DFS channels.
 #acs_exclude_dfs=1
 
+# Include only preferred scan channels from 6 GHz band for ACS
+# This option can be used to include only preferred scan channels in the 6 GHz
+# band. This can be useful in particular for devices that operate only a 6 GHz
+# BSS without a collocated 2.4/5 GHz BSS.
+# Default behavior is to include all PSC and non-PSC channels.
+#acs_exclude_6ghz_non_psc=1
+
 # Beacon interval in kus (1.024 ms) (default: 100; range 15..65535)
 beacon_int=100
 

src/ap/ap_config.h

@@ -886,6 +886,7 @@ struct hostapd_config {
 	u8 acs_freq_list_present;
 	int acs_exclude_dfs;
 	enum hostapd_hw_mode hw_mode; /* HOSTAPD_MODE_IEEE80211A, .. */
+	int acs_exclude_6ghz_non_psc;
 	enum {
 		LONG_PREAMBLE = 0,
 		SHORT_PREAMBLE = 1

src/ap/ap_drv_ops.c

@@ -869,6 +869,10 @@ static void hostapd_get_hw_mode_any_channels(struct hostapd_data *hapd,
 			     &hapd->iface->conf->acs_ch_list,
 			     chan->chan)))
 			continue;
+		if (is_6ghz_freq(chan->freq) &&
+		    hapd->iface->conf->acs_exclude_6ghz_non_psc &&
+		    !is_6ghz_psc_frequency(chan->freq))
+			continue;
 		if (!(chan->flag & HOSTAPD_CHAN_DISABLED) &&
 		    !(hapd->iface->conf->acs_exclude_dfs &&
 		      (chan->flag & HOSTAPD_CHAN_RADAR)))

src/common/ieee802_11_common.c

@@ -2069,6 +2069,26 @@ int is_6ghz_op_class(u8 op_class)
 }
 
 
+int is_6ghz_psc_frequency(int freq)
+{
+	int i;
+
+	if (!is_6ghz_freq(freq))
+		return 0;
+	if ((((freq - 5940) / 5) & 0x3) != 0x1)
+		return 0;
+
+	i = (freq - 5940 + 55) % 80;
+	if (i == 0)
+		i = (freq - 5940 + 55) / 80;
+
+	if (i >= 1 && i <= 15)
+		return 1;
+
+	return 0;
+}
+
+
 int ieee802_11_parse_candidate_list(const char *pos, u8 *nei_rep,
 				    size_t nei_rep_len)
 {

src/common/ieee802_11_common.h

@@ -226,6 +226,7 @@ int oper_class_bw_to_int(const struct oper_class_map *map);
 int center_idx_to_bw_6ghz(u8 idx);
 int is_6ghz_freq(int freq);
 int is_6ghz_op_class(u8 op_class);
+int is_6ghz_psc_frequency(int freq);
 
 int ieee802_11_parse_candidate_list(const char *pos, u8 *nei_rep,
 				    size_t nei_rep_len);