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

[Anson Huang <anson.huang@nxp.com>]

Hi, Eduardo

> -----Original Message-----
> From: Eduardo Valentin <edubezval@gmail.com>
> Sent: Wednesday, May 29, 2019 11:02 AM
> To: Anson Huang <anson.huang@nxp.com>
> Cc: robh+dt@kernel.org; mark.rutland@arm.com; shawnguo@kernel.org;
> s.hauer@pengutronix.de; kernel@pengutronix.de; festevam@gmail.com;
> catalin.marinas@arm.com; will.deacon@arm.com; rui.zhang@intel.com;
> daniel.lezcano@linaro.org; Aisheng Dong <aisheng.dong@nxp.com>;
> ulf.hansson@linaro.org; Peng Fan <peng.fan@nxp.com>; Daniel Baluta
> <daniel.baluta@nxp.com>; maxime.ripard@bootlin.com; olof@lixom.net;
> jagan@amarulasolutions.com; horms+renesas@verge.net.au; Leonard Crestez
> <leonard.crestez@nxp.com>; bjorn.andersson@linaro.org;
> dinguyen@kernel.org; enric.balletbo@collabora.com;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-pm@vger.kernel.org; dl-linux-imx <linux-
> imx@nxp.com>
> Subject: Re: [PATCH RESEND V13 2/5] thermal: of-thermal: add API for getting
> sensor ID from DT
> 
> 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/

As Rob has different opinion about this property, he thought it is unnecessary, see below
discussion mail, that is why I need to add API to get the resource ID from phandle argument.
I am totally confused now, which approach should we adopt?

https://patchwork.kernel.org/patch/10831397/

Thanks,
Anson

> 
> > ---
> >  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)