wifi: mt76: mt7925: support temperature sensor

Allow sensors tool to read radio's temperature, example:

mt7925_phy8-pci-3b00
Adapter: PCI adapter
temp1:        +35.0°C
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7925/init.c

@@ -2,11 +2,61 @@
 /* Copyright (C) 2023 MediaTek Inc. */
 
 #include <linux/etherdevice.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/thermal.h>
 #include <linux/firmware.h>
 #include "mt7925.h"
 #include "mac.h"
 #include "mcu.h"
 
+static ssize_t mt7925_thermal_temp_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	switch (to_sensor_dev_attr(attr)->index) {
+	case 0: {
+		struct mt792x_phy *phy = dev_get_drvdata(dev);
+		struct mt792x_dev *mdev = phy->dev;
+		int temperature;
+
+		mt792x_mutex_acquire(mdev);
+		temperature = mt7925_mcu_get_temperature(phy);
+		mt792x_mutex_release(mdev);
+
+		if (temperature < 0)
+			return temperature;
+		/* display in millidegree Celsius */
+		return sprintf(buf, "%u\n", temperature * 1000);
+	}
+	default:
+		return -EINVAL;
+	}
+}
+static SENSOR_DEVICE_ATTR_RO(temp1_input, mt7925_thermal_temp, 0);
+
+static struct attribute *mt7925_hwmon_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(mt7925_hwmon);
+
+static int mt7925_thermal_init(struct mt792x_phy *phy)
+{
+	struct wiphy *wiphy = phy->mt76->hw->wiphy;
+	struct device *hwmon;
+	const char *name;
+
+	if (!IS_REACHABLE(CONFIG_HWMON))
+		return 0;
+
+	name = devm_kasprintf(&wiphy->dev, GFP_KERNEL, "mt7925_%s",
+			      wiphy_name(wiphy));
+
+	hwmon = devm_hwmon_device_register_with_groups(&wiphy->dev, name, phy,
+						       mt7925_hwmon_groups);
+	return PTR_ERR_OR_ZERO(hwmon);
+}
 static void
 mt7925_regd_notifier(struct wiphy *wiphy,
 		     struct regulatory_request *req)
@@ -142,6 +192,12 @@ static void mt7925_init_work(struct work_struct *work)
 		return;
 	}
 
+	ret = mt7925_thermal_init(&dev->phy);
+	if (ret) {
+		dev_err(dev->mt76.dev, "thermal init failed\n");
+		return;
+	}
+
 	/* we support chip reset now */
 	dev->hw_init_done = true;
 

drivers/net/wireless/mediatek/mt76/mt7925/mcu.c

@@ -656,6 +656,42 @@ int mt7925_mcu_fw_log_2_host(struct mt792x_dev *dev, u8 ctrl)
 	return ret;
 }
 
+int mt7925_mcu_get_temperature(struct mt792x_phy *phy)
+{
+	struct {
+		u8 _rsv[4];
+
+		__le16 tag;
+		__le16 len;
+		u8 _rsv2[4];
+	} __packed req = {
+		.tag = cpu_to_le16(0x0),
+		.len = cpu_to_le16(sizeof(req) - 4),
+	};
+	struct mt7925_thermal_evt {
+		u8 rsv[4];
+		__le32 temperature;
+	} __packed * evt;
+	struct mt792x_dev *dev = phy->dev;
+	int temperature, ret;
+	struct sk_buff *skb;
+
+	ret = mt76_mcu_send_and_get_msg(&dev->mt76,
+					MCU_WM_UNI_CMD_QUERY(THERMAL),
+					&req, sizeof(req), true, &skb);
+	if (ret)
+		return ret;
+
+	skb_pull(skb, 4 + sizeof(struct tlv));
+	evt = (struct mt7925_thermal_evt *)skb->data;
+
+	temperature = le32_to_cpu(evt->temperature);
+
+	dev_kfree_skb(skb);
+
+	return temperature;
+}
+
 static void
 mt7925_mcu_parse_phy_cap(struct mt792x_dev *dev, char *data)
 {

drivers/net/wireless/mediatek/mt76/mt7925/mt7925.h

@@ -271,6 +271,7 @@ int mt7925_mcu_set_sniffer(struct mt792x_dev *dev, struct ieee80211_vif *vif,
 			   bool enable);
 int mt7925_mcu_config_sniffer(struct mt792x_vif *vif,
 			      struct ieee80211_chanctx_conf *ctx);
+int mt7925_mcu_get_temperature(struct mt792x_phy *phy);
 
 int mt7925_usb_sdio_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
 				   enum mt76_txq_id qid, struct mt76_wcid *wcid,