[PATCH 4/4] hwmon: (adt7470) Add thermal zone sensor support

[Luiz Angelo Daros de Luca <luizluca@gmail.com>]

Expose the ADT7470 external temperature sensors to the thermal framework
via Device Tree. The thermal callbacks use the driver's cached sensor data,
avoiding any I2C bus traffic during frequent polling by the thermal core.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
---
 drivers/hwmon/adt7470.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index b865f4bd50f8..44fe310f0650 100644
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -150,6 +150,11 @@ struct adt7470_cooling_device {
 	int pwm_index;
 };
 
+struct adt7470_thermal_sensor {
+	struct adt7470_data *data;
+	int id;
+};
+
 struct adt7470_data {
 	struct regmap		*regmap;
 	struct mutex		lock;
@@ -181,6 +186,7 @@ struct adt7470_data {
 	unsigned int		auto_update_interval;
 
 	struct adt7470_cooling_device cooling_devices[ADT7470_PWM_COUNT];
+	struct adt7470_thermal_sensor thermal_sensors[ADT7470_TEMP_COUNT];
 };
 
 /*
@@ -957,6 +963,47 @@ static int adt7470_register_cooling_devices(struct device *dev,
 	return 0;
 }
 
+static int adt7470_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct adt7470_thermal_sensor *sensor = thermal_zone_device_priv(tz);
+	struct adt7470_data *data = sensor->data;
+
+	mutex_lock(&data->lock);
+	*temp = 1000 * data->temp[sensor->id];
+	mutex_unlock(&data->lock);
+
+	return 0;
+}
+
+static const struct thermal_zone_device_ops adt7470_thermal_ops = {
+	.get_temp = adt7470_get_temp,
+};
+
+static int adt7470_register_thermal_sensors(struct device *dev,
+					    struct adt7470_data *data)
+{
+	int i;
+
+	for (i = 0; i < ADT7470_TEMP_COUNT; i++) {
+		struct thermal_zone_device *tz;
+
+		data->thermal_sensors[i].data = data;
+		data->thermal_sensors[i].id = i;
+
+		tz = devm_thermal_of_zone_register(dev, i, &data->thermal_sensors[i],
+						   &adt7470_thermal_ops);
+		if (IS_ERR(tz)) {
+			if (PTR_ERR(tz) == -ENODEV)
+				continue;
+			return dev_warn_probe(dev, PTR_ERR(tz),
+					      "failed to register thermal zone %d\n",
+					      i);
+		}
+	}
+
+	return 0;
+}
+
 static ssize_t pwm_max_show(struct device *dev,
 			    struct device_attribute *devattr, char *buf)
 {
@@ -1401,6 +1448,10 @@ static int adt7470_probe(struct i2c_client *client)
 		err = adt7470_register_cooling_devices(dev, data);
 		if (err)
 			return err;
+
+		err = adt7470_register_thermal_sensors(dev, data);
+		if (err)
+			return err;
 	}
 
 	data->auto_update = kthread_run(adt7470_update_thread, client, "%s",

-- 
2.55.0