Re: [PATCH RESEND V13 2/5] thermal: of-thermal: add API for getting sensor ID from DT

[Eduardo Valentin <edubezval@gmail.com>]

On Tue, May 28, 2019 at 02:06:18PM +0800, Anson.Huang@nxp.com wrote:
> From: Anson Huang <Anson.Huang@nxp.com>
> 
> On some platforms like i.MX8QXP, the thermal driver needs a
> real HW sensor ID from DT thermal zone, the HW sensor ID is
> used to get temperature from SCU firmware, and the virtual
> sensor ID starting from 0 to N is NOT used at all, this patch
> adds new API thermal_zone_of_get_sensor_id() to provide the
> feature of getting sensor ID from DT thermal zone's node.
> 
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> Changes since V12:
> 	- adjust the second parameter of thermal_zone_of_get_sensor_id() API, then caller no need
> 	  to pass the of_phandle_args structure and put the sensor_specs.np manually, also putting
> 	  the sensor node device check inside this API to make it easy for usage;

What happened to using nxp,resource-id property in your driver?
Why do we need this as an API in of-thermal? What other drivers may
benefit of this?

Regardless, this patch needs to document the new API under
Documentation/

> ---
>  drivers/thermal/of-thermal.c | 66 +++++++++++++++++++++++++++++++++-----------
>  include/linux/thermal.h      | 10 +++++++
>  2 files changed, 60 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
> index dc5093b..a53792b 100644
> --- a/drivers/thermal/of-thermal.c
> +++ b/drivers/thermal/of-thermal.c
> @@ -449,6 +449,54 @@ thermal_zone_of_add_sensor(struct device_node *zone,
>  }
>  
>  /**
> + * thermal_zone_of_get_sensor_id - get sensor ID from a DT thermal zone
> + * @tz_np: a valid thermal zone device node.
> + * @sensor_np: a sensor node of a valid sensor device.
> + * @id: a sensor ID pointer will be passed back.
> + *
> + * This function will get sensor ID from a given thermal zone node, use
> + * "thermal-sensors" as list name, and get sensor ID from first phandle's
> + * argument.
> + *
> + * Return: 0 on success, proper error code otherwise.
> + */
> +
> +int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
> +				  struct device_node *sensor_np,
> +				  u32 *id)
> +{
> +	struct of_phandle_args sensor_specs;
> +	int ret;
> +
> +	ret = of_parse_phandle_with_args(tz_np,
> +					 "thermal-sensors",
> +					 "#thermal-sensor-cells",
> +					 0,
> +					 &sensor_specs);
> +	if (ret)
> +		return ret;
> +
> +	if (sensor_specs.np != sensor_np) {
> +		of_node_put(sensor_specs.np);
> +		return -ENODEV;
> +	}
> +
> +	if (sensor_specs.args_count >= 1) {
> +		*id = sensor_specs.args[0];
> +		WARN(sensor_specs.args_count > 1,
> +		     "%pOFn: too many cells in sensor specifier %d\n",
> +		     sensor_specs.np, sensor_specs.args_count);
> +	} else {
> +		*id = 0;
> +	}
> +
> +	of_node_put(sensor_specs.np);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(thermal_zone_of_get_sensor_id);
> +
> +/**
>   * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
>   * @dev: a valid struct device pointer of a sensor device. Must contain
>   *       a valid .of_node, for the sensor node.
> @@ -499,36 +547,22 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
>  	sensor_np = of_node_get(dev->of_node);
>  
>  	for_each_available_child_of_node(np, child) {
> -		struct of_phandle_args sensor_specs;
>  		int ret, id;
>  
>  		/* For now, thermal framework supports only 1 sensor per zone */
> -		ret = of_parse_phandle_with_args(child, "thermal-sensors",
> -						 "#thermal-sensor-cells",
> -						 0, &sensor_specs);
> +		ret = thermal_zone_of_get_sensor_id(child, sensor_np, &id);
>  		if (ret)
>  			continue;
>  
> -		if (sensor_specs.args_count >= 1) {
> -			id = sensor_specs.args[0];
> -			WARN(sensor_specs.args_count > 1,
> -			     "%pOFn: too many cells in sensor specifier %d\n",
> -			     sensor_specs.np, sensor_specs.args_count);
> -		} else {
> -			id = 0;
> -		}
> -
> -		if (sensor_specs.np == sensor_np && id == sensor_id) {
> +		if (id == sensor_id) {
>  			tzd = thermal_zone_of_add_sensor(child, sensor_np,
>  							 data, ops);
>  			if (!IS_ERR(tzd))
>  				tzd->ops->set_mode(tzd, THERMAL_DEVICE_ENABLED);
>  
> -			of_node_put(sensor_specs.np);
>  			of_node_put(child);
>  			goto exit;
>  		}
> -		of_node_put(sensor_specs.np);
>  	}
>  exit:
>  	of_node_put(sensor_np);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 15a4ca5..5edffe6 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -375,6 +375,9 @@ struct thermal_trip {
>  
>  /* Function declarations */
>  #ifdef CONFIG_THERMAL_OF
> +int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
> +				  struct device_node *sensor_np,
> +				  u32 *id);
>  struct thermal_zone_device *
>  thermal_zone_of_sensor_register(struct device *dev, int id, void *data,
>  				const struct thermal_zone_of_device_ops *ops);
> @@ -386,6 +389,13 @@ struct thermal_zone_device *devm_thermal_zone_of_sensor_register(
>  void devm_thermal_zone_of_sensor_unregister(struct device *dev,
>  					    struct thermal_zone_device *tz);
>  #else
> +
> +static int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
> +					 struct device_node *sensor_np,
> +					 u32 *id)
> +{
> +	return -ENOENT;
> +}
>  static inline struct thermal_zone_device *
>  thermal_zone_of_sensor_register(struct device *dev, int id, void *data,
>  				const struct thermal_zone_of_device_ops *ops)