Re: [PATCH v4 07/10] iio: provide of_iio_channel_get_by_name() and devm_ version it

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 10 Sep 2020 16:59:57 +0300
Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:

> There might be cases when the IIO channel is attached to the device
> subnode instead of being attached to the main device node. Allow drivers
> to query IIO channels by using device tree nodes.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/iio/inkern.c         | 34 ++++++++++++++++++++++++++--------
>  include/linux/iio/consumer.h | 36 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index ede99e0d5371..8ff0ac472de3 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -180,8 +180,8 @@ static struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
>  	return ERR_PTR(err);
>  }
>  
> -static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
> -						      const char *name)
> +struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
> +					       const char *name)
>  {
>  	struct iio_channel *chan = NULL;
>  
> @@ -219,6 +219,7 @@ static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
>  
>  	return chan;
>  }
> +EXPORT_SYMBOL_GPL(of_iio_channel_get_by_name);
>  
>  static struct iio_channel *of_iio_channel_get_all(struct device *dev)
>  {
> @@ -261,12 +262,6 @@ static struct iio_channel *of_iio_channel_get_all(struct device *dev)
>  
>  #else /* CONFIG_OF */
>  
> -static inline struct iio_channel *
> -of_iio_channel_get_by_name(struct device_node *np, const char *name)
> -{
> -	return NULL;
> -}
> -
>  static inline struct iio_channel *of_iio_channel_get_all(struct device *dev)
>  {
>  	return NULL;
> @@ -382,6 +377,29 @@ struct iio_channel *devm_iio_channel_get(struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(devm_iio_channel_get);
>  
> +struct iio_channel *devm_of_iio_channel_get_by_name(struct device *dev,
> +						    struct device_node *np,
> +						    const char *channel_name)
> +{
> +	struct iio_channel **ptr, *channel;
> +
> +	ptr = devres_alloc(devm_iio_channel_free, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr)
> +		return ERR_PTR(-ENOMEM);
> +
> +	channel = of_iio_channel_get_by_name(np, channel_name);
> +	if (IS_ERR(channel)) {
> +		devres_free(ptr);
> +		return channel;
> +	}
> +
> +	*ptr = channel;
> +	devres_add(dev, ptr);
> +
> +	return channel;
> +}
> +EXPORT_SYMBOL_GPL(devm_of_iio_channel_get_by_name);
> +
>  struct iio_channel *iio_channel_get_all(struct device *dev)
>  {
>  	const char *name;
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index c4118dcb8e05..0a90ba8fa1bb 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -13,6 +13,7 @@
>  struct iio_dev;
>  struct iio_chan_spec;
>  struct device;
> +struct device_node;
>  
>  /**
>   * struct iio_channel - everything needed for a consumer to use a channel
> @@ -97,6 +98,41 @@ void iio_channel_release_all(struct iio_channel *chan);
>   */
>  struct iio_channel *devm_iio_channel_get_all(struct device *dev);
>  
> +/**
> + * of_iio_channel_get_by_name() - get description of all that is needed to access channel.
> + * @np:			Pointer to consumer device tree node
> + * @consumer_channel:	Unique name to identify the channel on the consumer
> + *			side. This typically describes the channels use within
> + *			the consumer. E.g. 'battery_voltage'
> + */
> +#ifdef CONFIG_OF
> +struct iio_channel *of_iio_channel_get_by_name(struct device_node *np, const char *name);
> +#else
> +static inline struct iio_channel *
> +of_iio_channel_get_by_name(struct device_node *np, const char *name)
> +{
> +	return NULL;
> +}
> +#endif
> +
> +/**
> + * devm_of_iio_channel_get_by_name() - Resource managed version of of_iio_channel_get_by_name().
> + * @dev:		Pointer to consumer device.
> + * @np:			Pointer to consumer device tree node
> + * @consumer_channel:	Unique name to identify the channel on the consumer
> + *			side. This typically describes the channels use within
> + *			the consumer. E.g. 'battery_voltage'
> + *
> + * Returns a pointer to negative errno if it is not able to get the iio channel
> + * otherwise returns valid pointer for iio channel.
> + *
> + * The allocated iio channel is automatically released when the device is
> + * unbound.
> + */
> +struct iio_channel *devm_of_iio_channel_get_by_name(struct device *dev,
> +						    struct device_node *np,
> +						    const char *consumer_channel);
> +
>  struct iio_cb_buffer;
>  /**
>   * iio_channel_get_all_cb() - register callback for triggered capture