From: "R, Durgadoss" <durgadoss.r@intel.com>
To: Eduardo Valentin <eduardo.valentin@ti.com>,
        "Zhang, Rui" <rui.zhang@intel.com>
CC: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCHv2 1/3] thermal: introduce thermal_zone_get_zone_by_name
 helper function
Thread-Topic: [PATCHv2 1/3] thermal: introduce thermal_zone_get_zone_by_name
 helper function
Thread-Index: AQHOMLiUY3LidhVScU+woWA60HaxEJjGTOCg
Date: Thu, 4 Apr 2013 17:12:12 +0000
Message-ID: <4D68720C2E767A4AA6A8796D42C8EB59C650A4@BGSMSX101.gar.corp.intel.com>
References: <1365027197-2793-1-git-send-email-eduardo.valentin@ti.com>
 <1365027197-2793-2-git-send-email-eduardo.valentin@ti.com>
In-Reply-To: <1365027197-2793-2-git-send-email-eduardo.valentin@ti.com>
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> -----Original Message-----
> From: Eduardo Valentin [mailto:eduardo.valentin@ti.com]
> Sent: Thursday, April 04, 2013 3:43 AM
> To: Zhang, Rui
> Cc: linux-pm@vger.kernel.org; linux-kernel@vger.kernel.org; R, Durgadoss;
> Eduardo Valentin
> Subject: [PATCHv2 1/3] thermal: introduce
> thermal_zone_get_zone_by_name helper function
> 
> This patch adds a helper function to get a reference of
> a thermal zone, based on the zone type name.
> 
> It will perform a zone name lookup and return a reference
> to a thermal zone device that matches the name requested.
> In case the zone is not found or when several zones match
> same name or if the required parameters are invalid, it will return
> the corresponding error code (ERR_PTR).
> 
> Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
> ---
>  drivers/thermal/thermal_sys.c |   34
> ++++++++++++++++++++++++++++++++++
>  include/linux/thermal.h       |    1 +
>  2 files changed, 35 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index 5bd95d4..6e1da0a 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -1790,6 +1790,40 @@ void thermal_zone_device_unregister(struct
> thermal_zone_device *tz)
>  }
>  EXPORT_SYMBOL_GPL(thermal_zone_device_unregister);
> 
> +/**
> + * thermal_zone_get_zone_by_name() - search for a zone and returns its
> ref
> + * @name: thermal zone name to fetch the temperature
> + *
> + * When only one zone is found with the passed name, returns a reference
> to it.
> + *
> + * Return: On success returns a reference to an unique thermal zone with
> + * matching name equals to @name, a ERR_PTR otherwise.
> + */
> +struct thermal_zone_device *thermal_zone_get_zone_by_name(const
> char *name)
> +{
> +	struct thermal_zone_device *pos = NULL, *ref = ERR_PTR(-EINVAL);
> +	int found = 0;
> +
> +	if (!name)
> +		goto exit;
> +
> +	mutex_lock(&thermal_list_lock);
> +	list_for_each_entry(pos, &thermal_tz_list, node)
> +		if (!strnicmp(name, pos->type, THERMAL_NAME_LENGTH)) {
> +			found++;
> +			ref = pos;
> +		}
> +	mutex_unlock(&thermal_list_lock);
> +
> +	/* Success only when an unique zone is found */
> +	if (found != 1)
> +		ref = ERR_PTR(-ENODEV);

I think we should differentiate between the two cases:
1. The zone does not exist at all
	return NULL in this case
2. There are multiple zones
	return ERR_PTR(-EEXIST) in this case

This way the calling function can figure out the exact reason
for failure.

Thanks,
Durga

> +
> +exit:
> +	return ref;
> +}
> +EXPORT_SYMBOL_GPL(thermal_zone_get_zone_by_name);
> +
>  #ifdef CONFIG_NET
>  static struct genl_family thermal_event_genl_family = {
>  	.id = GENL_ID_GENERATE,
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 542a39c..0cf9eb5 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -237,6 +237,7 @@ void thermal_zone_device_update(struct
> thermal_zone_device *);
>  struct thermal_cooling_device *thermal_cooling_device_register(char *,
> void *,
>  		const struct thermal_cooling_device_ops *);
>  void thermal_cooling_device_unregister(struct thermal_cooling_device *);
> +struct thermal_zone_device *thermal_zone_get_zone_by_name(const
> char *name);
> 
>  int thermal_zone_trend_get(struct thermal_zone_device *, int);
>  struct thermal_instance *thermal_instance_get(struct
> thermal_zone_device *,
> --
> 1.7.7.1.488.ge8e1c

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