Re: [Patch v3 4/5] hwmon: Support registration of thermal zones for SCP temperature sensors

[Punit Agrawal <punit.agrawal@arm.com>]

Please ignore this particular patch. I had an earlier one lying around
when I used git send-email *.

Punit Agrawal <punit.agrawal@arm.com> writes:

> Add support to create thermal zones based on the temperature sensors
> provided by the SCP. The thermal zones can be defined using the
> thermal DT bindings and should refer to the SCP sensor id to select
> the sensor.
>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Acked-by: Guenter Roeck <linux@roeck-us.net>
> Cc: Eduardo Valentin <edubezval@gmail.com>
> ---
>  drivers/hwmon/scpi-hwmon.c | 104 ++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 103 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/scpi-hwmon.c b/drivers/hwmon/scpi-hwmon.c
> index c7d1d14..2c1241b 100644
> --- a/drivers/hwmon/scpi-hwmon.c
> +++ b/drivers/hwmon/scpi-hwmon.c
> @@ -20,6 +20,7 @@
>  #include <linux/scpi_protocol.h>
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
> +#include <linux/thermal.h>
>  
>  struct sensor_data {
>  	struct scpi_sensor_info info;
> @@ -29,14 +30,39 @@ struct sensor_data {
>  	char label[20];
>  };
>  
> +struct scpi_thermal_zone {
> +	struct list_head list;
> +	int sensor_id;
> +	struct scpi_sensors *scpi_sensors;
> +	struct thermal_zone_device *tzd;
> +};
> +
>  struct scpi_sensors {
>  	struct scpi_ops *scpi_ops;
>  	struct sensor_data *data;
> +	struct list_head thermal_zones;
>  	struct attribute **attrs;
>  	struct attribute_group group;
>  	const struct attribute_group *groups[2];
>  };
>  
> +static int scpi_read_temp(void *dev, int *temp)
> +{
> +	struct scpi_thermal_zone *zone = dev;
> +	struct scpi_sensors *scpi_sensors = zone->scpi_sensors;
> +	struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
> +	struct sensor_data *sensor = &scpi_sensors->data[zone->sensor_id];
> +	u32 value;
> +	int ret;
> +
> +	ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
> +	if (ret)
> +		return ret;
> +
> +	*temp = value;
> +	return 0;
> +}
> +
>  /* hwmon callback functions */
>  static ssize_t
>  scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
> @@ -66,6 +92,24 @@ scpi_show_label(struct device *dev, struct device_attribute *attr, char *buf)
>  	return sprintf(buf, "%s\n", sensor->info.name);
>  }
>  
> +static void
> +unregister_thermal_zones(struct platform_device *pdev,
> +			 struct scpi_sensors *scpi_sensors)
> +{
> +	struct list_head *pos;
> +
> +	list_for_each(pos, &scpi_sensors->thermal_zones) {
> +		struct scpi_thermal_zone *zone;
> +
> +		zone = list_entry(pos, struct scpi_thermal_zone, list);
> +		thermal_zone_of_sensor_unregister(&pdev->dev, zone->tzd);
> +	}
> +}
> +
> +static struct thermal_zone_of_device_ops scpi_sensor_ops = {
> +	.get_temp = scpi_read_temp,
> +};
> +
>  static int scpi_hwmon_probe(struct platform_device *pdev)
>  {
>  	u16 nr_sensors, i;
> @@ -160,10 +204,67 @@ static int scpi_hwmon_probe(struct platform_device *pdev)
>  	scpi_sensors->group.attrs = scpi_sensors->attrs;
>  	scpi_sensors->groups[0] = &scpi_sensors->group;
>  
> +	platform_set_drvdata(pdev, scpi_sensors);
> +
>  	hwdev = devm_hwmon_device_register_with_groups(dev,
>  			"scpi_sensors", scpi_sensors, scpi_sensors->groups);
>  
> -	return PTR_ERR_OR_ZERO(hwdev);
> +	if (IS_ERR(hwdev))
> +		return PTR_ERR(hwdev);
> +
> +	/*
> +	 * Register the temperature sensors with the thermal framework
> +	 * to allow their usage in setting up the thermal zones from
> +	 * device tree.
> +	 *
> +	 * NOTE: Not all temperature sensors maybe used for thermal
> +	 * control
> +	 */
> +	INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
> +	for (i = 0; i < nr_sensors; i++) {
> +		struct sensor_data *sensor = &scpi_sensors->data[i];
> +		struct scpi_thermal_zone *zone;
> +
> +		if (sensor->info.class != TEMPERATURE)
> +			continue;
> +
> +		zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
> +		if (!zone) {
> +			ret = -ENOMEM;
> +			goto unregister_tzd;
> +		}
> +
> +		zone->sensor_id = i;
> +		zone->scpi_sensors = scpi_sensors;
> +		zone->tzd = thermal_zone_of_sensor_register(dev, i, zone,
> +							    &scpi_sensor_ops);
> +		/*
> +		 * The call to thermal_zone_of_sensor_register returns
> +		 * an error for sensors that are not associated with
> +		 * any thermal zones or if the thermal subsystem is
> +		 * not configured.
> +		 */
> +		if (IS_ERR(zone->tzd)) {
> +			devm_kfree(dev, zone);
> +			continue;
> +		}
> +		list_add(&zone->list, &scpi_sensors->thermal_zones);
> +	}
> +
> +	return 0;
> +
> +unregister_tzd:
> +	unregister_thermal_zones(pdev, scpi_sensors);
> +	return ret;
> +}
> +
> +static int scpi_hwmon_remove(struct platform_device *pdev)
> +{
> +	struct scpi_sensors *scpi_sensors = platform_get_drvdata(pdev);
> +
> +	unregister_thermal_zones(pdev, scpi_sensors);
> +
> +	return 0;
>  }
>  
>  static const struct of_device_id scpi_of_match[] = {
> @@ -178,6 +279,7 @@ static struct platform_driver scpi_hwmon_platdrv = {
>  		.of_match_table = scpi_of_match,
>  	},
>  	.probe		= scpi_hwmon_probe,
> +	.remove		= scpi_hwmon_remove,
>  };
>  module_platform_driver(scpi_hwmon_platdrv);