mt76: connac: add support for limiting to maximum regulatory Tx power

Consider .max_reg_power in struct ieee80211_channel to limit the
maximum power the wireless device allowed to transmit on the
corresponding channel according to the regulatory domain.
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: YN Chen <YN.Chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c

@@ -1773,6 +1773,43 @@ static s8 mt76_connac_get_sar_power(struct mt76_phy *phy,
 	return target_power;
 }
 
+static s8 mt76_connac_get_ch_power(struct mt76_phy *phy,
+				   struct ieee80211_channel *chan,
+				   s8 target_power)
+{
+	struct mt76_dev *dev = phy->dev;
+	struct ieee80211_supported_band *sband;
+	int i;
+
+	switch (chan->band) {
+	case NL80211_BAND_2GHZ:
+		sband = &phy->sband_2g.sband;
+		break;
+	case NL80211_BAND_5GHZ:
+		sband = &phy->sband_5g.sband;
+		break;
+	default:
+		return target_power;
+	}
+
+	for (i = 0; i < sband->n_channels; i++) {
+		struct ieee80211_channel *ch = &sband->channels[i];
+
+		if (ch->hw_value == chan->hw_value) {
+			if (!(ch->flags & IEEE80211_CHAN_DISABLED)) {
+				int power = 2 * ch->max_reg_power;
+
+				if (is_mt7663(dev) && (power > 63 || power < -64))
+					power = 63;
+				target_power = min_t(s8, power, target_power);
+			}
+			break;
+		}
+	}
+
+	return target_power;
+}
+
 static int
 mt76_connac_mcu_rate_txpower_band(struct mt76_phy *phy,
 				  enum nl80211_band band)
@@ -1840,10 +1877,12 @@ mt76_connac_mcu_rate_txpower_band(struct mt76_phy *phy,
 				.hw_value = ch_list[idx],
 				.band = band,
 			};
-			s8 sar_power;
+			s8 reg_power, sar_power;
 
+			reg_power = mt76_connac_get_ch_power(phy, &chan,
+							     tx_power);
 			sar_power = mt76_connac_get_sar_power(phy, &chan,
-							      tx_power);
+							      reg_power);
 
 			mt76_get_rate_power_limits(phy, &chan, &limits,
 						   sar_power);