mt76: mt7615: measure channel noise and report it via survey

Read measurements every 100 ms and build a simple moving average
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -618,6 +618,9 @@ int mt76_get_survey(struct ieee80211_hw *hw, int idx,
 	survey->channel = chan;
 	survey->filled = SURVEY_INFO_TIME | SURVEY_INFO_TIME_BUSY;
 	survey->filled |= dev->drv->survey_flags;
+	if (state->noise)
+		survey->filled |= SURVEY_INFO_NOISE_DBM;
+
 	if (chan == phy->main_chan) {
 		survey->filled |= SURVEY_INFO_IN_USE;
 
@@ -628,6 +631,7 @@ int mt76_get_survey(struct ieee80211_hw *hw, int idx,
 	survey->time_busy = div_u64(state->cc_busy, 1000);
 	survey->time_rx = div_u64(state->cc_rx, 1000);
 	survey->time = div_u64(state->cc_active, 1000);
+	survey->noise = state->noise;
 
 	spin_lock_bh(&dev->cc_lock);
 	survey->time_bss_rx = div_u64(state->cc_bss_rx, 1000);

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -328,6 +328,8 @@ struct mt76_channel_state {
 	u64 cc_rx;
 	u64 cc_bss_rx;
 	u64 cc_tx;
+
+	s8 noise;
 };
 
 struct mt76_sband {

drivers/net/wireless/mediatek/mt76/mt7615/mac.c

@@ -1379,6 +1379,19 @@ void mt7615_mac_set_scs(struct mt7615_dev *dev, bool enable)
 	mutex_unlock(&dev->mt76.mutex);
 }
 
+void mt7615_mac_enable_nf(struct mt7615_dev *dev, bool ext_phy)
+{
+	u32 rxtd;
+
+	if (ext_phy)
+		rxtd = MT_WF_PHY_RXTD2(10);
+	else
+		rxtd = MT_WF_PHY_RXTD(12);
+
+	mt76_set(dev, rxtd, BIT(18) | BIT(29));
+	mt76_set(dev, MT_WF_PHY_R0_PHYMUX_5(ext_phy), 0x5 << 12);
+}
+
 void mt7615_mac_cca_stats_reset(struct mt7615_phy *phy)
 {
 	struct mt7615_dev *dev = phy->dev;
@@ -1511,13 +1524,35 @@ mt7615_mac_scs_check(struct mt7615_phy *phy)
 		mt7615_mac_set_default_sensitivity(phy);
 }
 
+static u8
+mt7615_phy_get_nf(struct mt7615_dev *dev, int idx)
+{
+	static const u8 nf_power[] = { 92, 89, 86, 83, 80, 75, 70, 65, 60, 55, 52 };
+	u32 reg = idx ? MT_WF_PHY_RXTD2(17) : MT_WF_PHY_RXTD(20);
+	u32 val, sum = 0, n = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(nf_power); i++, reg += 4) {
+		val = mt76_rr(dev, reg);
+		sum += val * nf_power[i];
+		n += val;
+	}
+
+	if (!n)
+		return 0;
+
+	return sum / n;
+}
+
 static void
 mt7615_phy_update_channel(struct mt76_phy *mphy, int idx)
 {
 	struct mt7615_dev *dev = container_of(mphy->dev, struct mt7615_dev, mt76);
+	struct mt7615_phy *phy = mphy->priv;
 	struct mt76_channel_state *state;
 	u64 busy_time, tx_time, rx_time, obss_time;
 	u32 obss_reg = idx ? MT_WF_RMAC_MIB_TIME6 : MT_WF_RMAC_MIB_TIME5;
+	int nf;
 
 	busy_time = mt76_get_field(dev, MT_MIB_SDR9(idx),
 				   MT_MIB_SDR9_BUSY_MASK);
@@ -1527,11 +1562,18 @@ mt7615_phy_update_channel(struct mt76_phy *mphy, int idx)
 				 MT_MIB_SDR37_RXTIME_MASK);
 	obss_time = mt76_get_field(dev, obss_reg, MT_MIB_OBSSTIME_MASK);
 
+	nf = mt7615_phy_get_nf(dev, idx);
+	if (!phy->noise)
+		phy->noise = nf << 4;
+	else if (nf)
+		phy->noise += nf - (phy->noise >> 4);
+
 	state = mphy->chan_state;
 	state->cc_busy += busy_time;
 	state->cc_tx += tx_time;
 	state->cc_rx += rx_time + obss_time;
 	state->cc_bss_rx += rx_time;
+	state->noise = -(phy->noise >> 4);
 }
 
 void mt7615_update_channel(struct mt76_dev *mdev)

drivers/net/wireless/mediatek/mt76/mt7615/main.c

@@ -40,11 +40,13 @@ static int mt7615_start(struct ieee80211_hw *hw)
 	if (!running) {
 		mt7615_mcu_ctrl_pm_state(dev, 0, 0);
 		mt7615_mcu_set_mac_enable(dev, 0, true);
+		mt7615_mac_enable_nf(dev, 0);
 	}
 
 	if (phy != &dev->phy) {
 		mt7615_mcu_ctrl_pm_state(dev, 1, 0);
 		mt7615_mcu_set_mac_enable(dev, 1, true);
+		mt7615_mac_enable_nf(dev, 1);
 	}
 
 	set_bit(MT76_STATE_RUNNING, &phy->mt76->state);
@@ -238,6 +240,7 @@ static int mt7615_set_channel(struct mt7615_phy *phy)
 	mt7615_mac_cca_stats_reset(phy);
 
 	mt7615_mac_reset_counters(dev);
+	phy->noise = 0;
 
 out:
 	clear_bit(MT76_RESET, &phy->mt76->state);

drivers/net/wireless/mediatek/mt76/mt7615/mt7615.h

@@ -94,6 +94,8 @@ struct mt7615_phy {
 	u32 rxfilter;
 	u32 omac_mask;
 
+	u16 noise;
+
 	unsigned long last_cca_adj;
 	int false_cca_ofdm, false_cca_cck;
 	s8 ofdm_sensitivity;
@@ -288,6 +290,7 @@ bool mt7615_mac_wtbl_update(struct mt7615_dev *dev, int idx, u32 mask);
 void mt7615_mac_reset_counters(struct mt7615_dev *dev);
 void mt7615_mac_cca_stats_reset(struct mt7615_phy *phy);
 void mt7615_mac_set_scs(struct mt7615_dev *dev, bool enable);
+void mt7615_mac_enable_nf(struct mt7615_dev *dev, bool ext_phy);
 void mt7615_mac_sta_poll(struct mt7615_dev *dev);
 int mt7615_mac_write_txwi(struct mt7615_dev *dev, __le32 *txwi,
 			  struct sk_buff *skb, struct mt76_wcid *wcid,

drivers/net/wireless/mediatek/mt76/mt7615/regs.h

@@ -104,6 +104,9 @@
 #define MT_WF_PHY_B1_PD_OFDM(v)		((v) << 16)
 #define MT_WF_PHY_B1_PD_BLK		BIT(25)
 
+#define MT_WF_PHY_RXTD_BASE		MT_WF_PHY(0x2200)
+#define MT_WF_PHY_RXTD(_n)		(MT_WF_PHY_RXTD_BASE + ((_n) << 2))
+
 #define MT_WF_PHY_B0_RXTD_CCK_PD	MT_WF_PHY(0x2310)
 #define MT_WF_PHY_B0_PD_CCK_MASK	GENMASK(8, 1)
 #define MT_WF_PHY_B0_PD_CCK(v)		((v) << 1)
@@ -112,6 +115,9 @@
 #define MT_WF_PHY_B1_PD_CCK_MASK	GENMASK(31, 24)
 #define MT_WF_PHY_B1_PD_CCK(v)		((v) << 24)
 
+#define MT_WF_PHY_RXTD2_BASE		MT_WF_PHY(0x2a00)
+#define MT_WF_PHY_RXTD2(_n)		(MT_WF_PHY_RXTD2_BASE + ((_n) << 2))
+
 #define MT_WF_CFG_BASE			0x20200
 #define MT_WF_CFG(ofs)			(MT_WF_CFG_BASE + (ofs))