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@xxxxxxxxxxx>
> ---
> .../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
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