linux-kernel - Re: [PATCH 2/3] iio: core: Add devm_ APIs for iio_channel_{get,release}

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Message-ID: <57137C2E.30702@kernel.org>
Date:	Sun, 17 Apr 2016 13:06:06 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Laxman Dewangan <ldewangan@...dia.com>, corbet@....net,
	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net
Cc:	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org
Subject: Re: [PATCH 2/3] iio: core: Add devm_ APIs for
 iio_channel_{get,release}_all

On 06/04/16 11:31, Laxman Dewangan wrote:
> Some of kernel driver uses the IIO framework to get the sensor
> value via ADC or IIO HW driver. The client driver get iio channel
> by iio_channel_get_all() and release it by calling
> iio_channel_release_all().
> 
> Add resource managed version (devm_*) of these APIs so that if client
> calls the devm_iio_channel_get_all() then it need not to release it
> explicitly, it can be done by managed device framework when driver
> get un-binded.
> 
> This reduces the code in error path and also need of .remove callback in
> some cases.
> 
> Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
Applied to the togreg branch of iio.git.  Thanks,

Jonathan
> ---
>  drivers/iio/inkern.c         | 36 ++++++++++++++++++++++++++++++++++++
>  include/linux/iio/consumer.h | 26 ++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index 18e623f..8c1abfe 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -489,6 +489,42 @@ void iio_channel_release_all(struct iio_channel *channels)
>  }
>  EXPORT_SYMBOL_GPL(iio_channel_release_all);
>  
> +static void devm_iio_channel_free_all(struct device *dev, void *res)
> +{
> +	struct iio_channel *channels = *(struct iio_channel **)res;
> +
> +	iio_channel_release_all(channels);
> +}
> +
> +struct iio_channel *devm_iio_channel_get_all(struct device *dev)
> +{
> +	struct iio_channel **ptr, *channels;
> +
> +	ptr = devres_alloc(devm_iio_channel_free_all, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr)
> +		return ERR_PTR(-ENOMEM);
> +
> +	channels = iio_channel_get_all(dev);
> +	if (IS_ERR(channels)) {
> +		devres_free(ptr);
> +		return channels;
> +	}
> +
> +	*ptr = channels;
> +	devres_add(dev, ptr);
> +
> +	return channels;
> +}
> +EXPORT_SYMBOL_GPL(devm_iio_channel_get_all);
> +
> +void devm_iio_channel_release_all(struct device *dev,
> +				  struct iio_channel *channels)
> +{
> +	WARN_ON(devres_release(dev, devm_iio_channel_free_all,
> +			       devm_iio_channel_match, channels));
> +}
> +EXPORT_SYMBOL_GPL(devm_iio_channel_release_all);
> +
>  static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
>  	enum iio_chan_info_enum info)
>  {
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index e1e033d..3d672f7 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -92,6 +92,32 @@ struct iio_channel *iio_channel_get_all(struct device *dev);
>   */
>  void iio_channel_release_all(struct iio_channel *chan);
>  
> +/**
> + * devm_iio_channel_get_all() - Resource managed version of
> + *				iio_channel_get_all().
> + * @dev: Pointer to consumer device.
> + *
> + * Returns a pointer to negative errno if it is not able to get the iio channel
> + * otherwise returns an array of iio_channel structures terminated with one with
> + * null iio_dev pointer.
> + *
> + * This function is used by fairly generic consumers to get all the
> + * channels registered as having this consumer.
> + *
> + * The allocated iio channels are automatically released when the device is
> + * unbounded.
> + */
> +struct iio_channel *devm_iio_channel_get_all(struct device *dev);
> +
> +/**
> + * devm_iio_channel_release_all() - Resource managed version of
> + *				    iio_channel_release_all().
> + * @dev:		Pointer to consumer device for which resource
> + *			is allocared.
> + * @chan:		Array channel to be released.
> + */
> +void devm_iio_channel_release_all(struct device *dev, struct iio_channel *chan);
> +
>  struct iio_cb_buffer;
>  /**
>   * iio_channel_get_all_cb() - register callback for triggered capture
>