wl1271: add get_survey callback in order to get channel noise

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Acked-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>

drivers/net/wireless/wl12xx/wl1271.h

@@ -475,6 +475,9 @@ struct wl1271 {
 	bool sg_enabled;
 
 	struct list_head list;
+
+	/* Most recently reported noise in dBm */
+	s8 noise;
 };
 
 int wl1271_plt_start(struct wl1271 *wl);

drivers/net/wireless/wl12xx/wl1271_main.c

@@ -1927,6 +1927,22 @@ out:
 	return mactime;
 }
 
+static int wl1271_op_get_survey(struct ieee80211_hw *hw, int idx,
+				struct survey_info *survey)
+{
+	struct wl1271 *wl = hw->priv;
+	struct ieee80211_conf *conf = &hw->conf;
+ 
+	if (idx != 0)
+		return -ENOENT;
+ 
+	survey->channel = conf->channel;
+	survey->filled = SURVEY_INFO_NOISE_DBM;
+	survey->noise = wl->noise;
+ 
+	return 0;
+}
+
 /* can't be const, mac80211 writes to this */
 static struct ieee80211_rate wl1271_rates[] = {
 	{ .bitrate = 10,
@@ -2156,6 +2172,7 @@ static const struct ieee80211_ops wl1271_ops = {
 	.set_rts_threshold = wl1271_op_set_rts_threshold,
 	.conf_tx = wl1271_op_conf_tx,
 	.get_tsf = wl1271_op_get_tsf,
+	.get_survey = wl1271_op_get_survey,
 	CFG80211_TESTMODE_CMD(wl1271_tm_cmd)
 };
 

drivers/net/wireless/wl12xx/wl1271_rx.c

@@ -55,6 +55,13 @@ static void wl1271_rx_status(struct wl1271 *wl,
 
 	status->signal = desc->rssi;
 
+	/*
+	 * FIXME: In wl1251, the SNR should be divided by two.  In wl1271 we
+	 * need to divide by two for now, but TI has been discussing about
+	 * changing it.  This needs to be rechecked.
+	 */
+	wl->noise = desc->rssi - (desc->snr >> 1);
+
 	status->freq = ieee80211_channel_to_frequency(desc->channel);
 
 	if (desc->flags & WL1271_RX_DESC_ENCRYPT_MASK) {