[PATCH 05/16] hwmon: lm75: expose to thermal fw via DT nodes

[Eduardo Valentin]

This patch adds to lm75 temperature sensor the possibility
to expose itself as thermal zone device, registered on the
thermal framework.

The thermal zone is built only if a device tree node
describing a thermal zone for this sensor is present
inside the lm75 DT node. Otherwise, the driver behavior
will be the same.

Cc: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: lm-sensors@xxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxx>
---
 drivers/hwmon/lm75.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index c03b490..2ba09ef 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -27,6 +27,8 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/thermal.h>
 #include "lm75.h"
 
 
@@ -70,6 +72,7 @@ static const u8 LM75_REG_TEMP[3] = {
 /* Each client has this additional data */
 struct lm75_data {
 	struct device		*hwmon_dev;
+	struct thermal_zone_device	*tz;
 	struct mutex		update_lock;
 	u8			orig_conf;
 	u8			resolution;	/* In bits, between 9 and 12 */
@@ -90,22 +93,42 @@ static struct lm75_data *lm75_update_device(struct device *dev);
 
 /*-----------------------------------------------------------------------*/
 
+static inline long lm75_reg_to_mc(s16 temp, u8 resolution)
+{
+	return ((temp >> (16 - resolution)) * 1000) >> (resolution - 8);
+}
+
 /* sysfs attributes for hwmon */
 
+static int lm75_read_temp(void *dev, long *temp)
+{
+	struct lm75_data *data = lm75_update_device(dev);
+	long temperature;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	temperature = lm75_reg_to_mc(data->temp[0], data->resolution);
+	if (temperature < 0)
+		dev_warn(data->hwmon_dev,
+			 "operating in negative temp: %ld\n", temperature);
+
+	*temp = temperature;
+
+	return 0;
+}
+
 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
 			 char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct lm75_data *data = lm75_update_device(dev);
-	long temp;
 
 	if (IS_ERR(data))
 		return PTR_ERR(data);
 
-	temp = ((data->temp[attr->index] >> (16 - data->resolution)) * 1000)
-	       >> (data->resolution - 8);
-
-	return sprintf(buf, "%ld\n", temp);
+	return sprintf(buf, "%ld\n", lm75_reg_to_mc(data->temp[attr->index],
+						    data->resolution));
 }
 
 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
@@ -271,6 +294,17 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		goto exit_remove;
 	}
 
+	data->tz = thermal_zone_of_sensor_register(&client->dev,
+						   0,
+						   &client->dev,
+						   lm75_read_temp, NULL);
+	if (IS_ERR(data->tz)) {
+		dev_warn(&client->dev,
+			 "Could not parse thermal data in device tree: %ld\n",
+			 PTR_ERR(data->tz));
+		data->tz = NULL;
+	}
+
 	dev_info(&client->dev, "%s: sensor '%s'\n",
 		 dev_name(data->hwmon_dev), client->name);
 
@@ -285,6 +319,8 @@ static int lm75_remove(struct i2c_client *client)
 {
 	struct lm75_data *data = i2c_get_clientdata(client);
 
+	/* thermal zone life cycle is not our responsibility */
+	thermal_zone_of_sensor_unregister(&client->dev, data->tz);
 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
 	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
-- 
1.8.2.1.342.gfa7285d

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