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

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

[Jonghwa Lee]

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.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
---
 .../devicetree/bindings/hwmon/ntc_thermistor.txt   |    3 +++
 drivers/hwmon/ntc_thermistor.c                     |   26 ++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
index 2391e5c..fcca8e7 100644
--- a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
+++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
@@ -25,6 +25,9 @@ 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/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index bd41072..369dc8c 100644
--- 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;
@@ -182,6 +183,7 @@ 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)
@@ -428,6 +430,20 @@ 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)
 {
@@ -562,6 +578,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
 								pdev_id->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);
@@ -578,6 +601,9 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 	ntc_iio_channel_release(pdata);
 
+	if (data->tz)
+		thermal_zone_of_sensor_unregister(data->dev, data->tz);
+
 	return 0;
 }
 
-- 
1.7.9.5

Re: [PATCH] hwmon: ntc_thermistor: Add ntc thermistor to thermal subsystem as a sensor.

[Chanwoo Choi]

Hi Jonghwa,

On 08/26/2014 02:33 PM, Jonghwa Lee wrote:
> 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.
> 
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
> ---
>  .../devicetree/bindings/hwmon/ntc_thermistor.txt   |    3 +++
>  drivers/hwmon/ntc_thermistor.c                     |   26 ++++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
> index 2391e5c..fcca8e7 100644
> --- a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
> +++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
> @@ -25,6 +25,9 @@ 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/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
> index bd41072..369dc8c 100644
> --- 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;
> @@ -182,6 +183,7 @@ 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)
> @@ -428,6 +430,20 @@ 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)
>  {
> @@ -562,6 +578,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
>  								pdev_id->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);
> @@ -578,6 +601,9 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
>  	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
>  	ntc_iio_channel_release(pdata);
>  
> +	if (data->tz)
> +		thermal_zone_of_sensor_unregister(data->dev, data->tz);

thermal_zone_of_sensor_unregister just return without operation if data->tz is NULL.
So, don't need to check the value of data->tz with if statement.

Thanks,
Chanwoo Choi

Re: [PATCH] hwmon: ntc_thermistor: Add ntc thermistor to thermal subsystem as a sensor.

[Guenter Roeck]

On 08/26/2014 03:12 AM, Chanwoo Choi wrote:
> Hi Jonghwa,
>
> On 08/26/2014 02:33 PM, Jonghwa Lee wrote:
>> 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.
>>
>> Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
>> ---
>>   .../devicetree/bindings/hwmon/ntc_thermistor.txt   |    3 +++
>>   drivers/hwmon/ntc_thermistor.c                     |   26 ++++++++++++++++++++
>>   2 files changed, 29 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
>> index 2391e5c..fcca8e7 100644
>> --- a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
>> +++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
>> @@ -25,6 +25,9 @@ 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/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
>> index bd41072..369dc8c 100644
>> --- 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;
>> @@ -182,6 +183,7 @@ 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)
>> @@ -428,6 +430,20 @@ 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)
>>   {
>> @@ -562,6 +578,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>>   	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
>>   								pdev_id->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);
>> @@ -578,6 +601,9 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
>>   	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
>>   	ntc_iio_channel_release(pdata);
>>
>> +	if (data->tz)
>> +		thermal_zone_of_sensor_unregister(data->dev, data->tz);
>
> thermal_zone_of_sensor_unregister just return without operation if data->tz is NULL.
> So, don't need to check the value of data->tz with if statement.
>

On a side note, devm_thermal_zone_of_sensor_register would be quite useful to have.

Guenter