hwmon: ntc_thermistor: Add ntc thermistor to thermal subsystem as a sensor.

To get more comprehensive and integrated thermal management, it adds ntc
thermistor to thermal framework as a thermal sensor. It's governed thermal
susbsystem only if it is described in DT node. Otherwise, it just notifies
temperature to userspace via sysfs as it used to be.

Change-Id: Ie5b8948ca0cb567854905e0e9ea903ff7cdc1f4c
Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>

diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
index c6f6667..bdae6df 100644 (file)
--- a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
+++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
@@ -16,6 +16,9 @@ Requires node properties:
 - "io-channels"        Channel node of ADC to be used for
                conversion.
 
+Optional node properties:
+- "#thermal-sensor-cells" Used to expose itself to thermal fw.
+
 Read more about iio bindings at
        Documentation/devicetree/bindings/iio/iio-bindings.txt
 

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index a8b0c7c..5399c32 100644 (file)
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -945,6 +945,7 @@ config SENSORS_NCT6775
 config SENSORS_NTC_THERMISTOR
        tristate "NTC thermistor support"
        depends on !OF || IIO=n || IIO
+       depends on THERMAL || !THERMAL_OF
        help
          This driver supports NTC thermistors sensor reading and its
          interpretation. The driver can also monitor the temperature and

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index c64d3d4..1eccf10 100644 (file)
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -38,6 +38,7 @@
 
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
+#include <linux/thermal.h>
 
 struct ntc_compensation {
        int             temp_c;
@@ -140,6 +141,7 @@ struct ntc_data {
        struct device *dev;
        int n_comp;
        char name[PLATFORM_NAME_SIZE];
+       struct thermal_zone_device *tz;
 };
 
 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
@@ -372,6 +374,20 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data)
        return -EINVAL;
 }
 
+static int ntc_read_temp(void *dev, long *temp)
+{
+       struct ntc_data *data = dev_get_drvdata(dev);
+       int ohm;
+
+       ohm = ntc_thermistor_get_ohm(data);
+       if (ohm < 0)
+               return ohm;
+
+       *temp = get_temp_mc(data, ohm);
+
+       return 0;
+}
+
 static ssize_t ntc_show_name(struct device *dev,
                struct device_attribute *attr, char *buf)
 {
@@ -502,6 +518,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
        dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
                                                                pdev->name);
 
+       data->tz = thermal_zone_of_sensor_register(data->dev, 0, data->dev,
+                                               ntc_read_temp, NULL);
+       if (IS_ERR(data->tz)) {
+               dev_dbg(&pdev->dev, "Failed to register to thermal fw.\n");
+               data->tz = NULL;
+       }
+
        return 0;
 err_after_sysfs:
        sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
@@ -519,6 +542,8 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
        ntc_iio_channel_release(pdata);
        platform_set_drvdata(pdev, NULL);
 
+       thermal_zone_of_sensor_unregister(data->dev, data->tz);
+
        return 0;
 }