[RFC PATCH 03/14] hwmon: lm75: expose to thermal fw via DT nodes

[Eduardo Valentin <eduardo.valentin@ti.com>]

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@linux-fr.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: lm-sensors@lm-sensors.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
---
 drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index c03b490..dc55908 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/thermal.h>
+#include <linux/of.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 */
@@ -92,6 +95,19 @@ static struct lm75_data *lm75_update_device(struct device *dev);
 
 /* sysfs attributes for hwmon */
 
+static int lm75_read_temp(void *dev, unsigned long *temp)
+{
+	struct lm75_data *data = lm75_update_device(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	*temp = ((data->temp[0] >> (16 - data->resolution)) * 1000) >>
+			(data->resolution - 8);
+
+	return 0;
+}
+
 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
 			 char *buf)
 {
@@ -271,11 +287,25 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		goto exit_remove;
 	}
 
+	if (of_find_property(client->dev.of_node, "monitored-zones", NULL)) {
+		data->tz = thermal_zone_of_device_register(&client->dev,
+							   0,
+							   false, /* -hwmon */
+							   &client->dev,
+							   lm75_read_temp);
+		if (IS_ERR(data->tz)) {
+			status = PTR_ERR(data->tz);
+			goto exit_hwmon;
+		}
+	}
+
 	dev_info(&client->dev, "%s: sensor '%s'\n",
 		 dev_name(data->hwmon_dev), client->name);
 
 	return 0;
 
+exit_hwmon:
+	hwmon_device_unregister(data->hwmon_dev);
 exit_remove:
 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
 	return status;
@@ -285,6 +315,7 @@ static int lm75_remove(struct i2c_client *client)
 {
 	struct lm75_data *data = i2c_get_clientdata(client);
 
+	thermal_zone_device_unregister(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