Re: [PATCH v4 06/11] media: v4l2-fwnode: Add helper to parse device properties

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Jacopo,

On Mon, Oct 07, 2019 at 06:29:08PM +0200, Jacopo Mondi wrote:
> Add an helper function to parse common device properties in the same
> way as v4l2_fwnode_endpoint_parse() parses common endpoint properties.
> 
> Parse the 'rotation' and 'location' properties from the firmware
> interface.
> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>  drivers/media/v4l2-core/v4l2-fwnode.c | 42 +++++++++++++++++++++++
>  include/media/v4l2-fwnode.h           | 48 +++++++++++++++++++++++++++
>  2 files changed, 90 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> index 192cac076761..8af4174a2bbf 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -596,6 +596,48 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
>  }
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
>  
> +int v4l2_fwnode_device_parse(struct device *dev,
> +			     struct v4l2_fwnode_device_properties *props)
> +{
> +	struct fwnode_handle *fwnode = dev_fwnode(dev);
> +	u32 val;
> +	int ret;
> +
> +	memset(props, 0, sizeof(*props));
> +
> +	props->location = V4L2_FWNODE_PROPERTY_UNSET;

How about adding V4L2_FWNODE_LOCATION_UNDEFINED instead? Same for the
rotation. I'd use 0 for that value, so memset above already sets it.

> +	ret = fwnode_property_read_u32(fwnode, "location", &val);
> +	if (!ret) {
> +		switch (val) {
> +		case V4L2_FWNODE_LOCATION_FRONT:
> +		case V4L2_FWNODE_LOCATION_BACK:
> +		case V4L2_FWNODE_LOCATION_EXTERNAL:
> +			break;
> +		default:
> +			dev_warn(dev, "Unsupported device location: %u\n", val);
> +			return -EINVAL;
> +		}
> +
> +		props->location = val;
> +		dev_dbg(dev, "device location: %u\n", val);
> +	}
> +
> +	props->rotation = V4L2_FWNODE_PROPERTY_UNSET;
> +	ret = fwnode_property_read_u32(fwnode, "rotation", &val);
> +	if (!ret) {
> +		if (val >= 360 || val % 90) {
> +			dev_warn(dev, "Unsupported device rotation: %u\n", val);

I think it should be up to the caller to determine what's supported.

> +			return -EINVAL;
> +		}
> +
> +		props->rotation = val;
> +		dev_dbg(dev, "device rotation: %u\n", val);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_fwnode_device_parse);
> +
>  static int
>  v4l2_async_notifier_fwnode_parse_endpoint(struct device *dev,
>  					  struct v4l2_async_notifier *notifier,
> diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> index f6a7bcd13197..6d46d6fc3007 100644
> --- a/include/media/v4l2-fwnode.h
> +++ b/include/media/v4l2-fwnode.h
> @@ -109,6 +109,36 @@ struct v4l2_fwnode_endpoint {
>  	unsigned int nr_of_link_frequencies;
>  };
>  
> +/**
> + * v4l2_fwnode_location - identify a non initialized property.
> + *
> + * All properties in &struct v4l2_fwnode_device_properties are initialized
> + * to this value.
> + */
> +#define V4L2_FWNODE_PROPERTY_UNSET   (-1U)
> +
> +/**
> + * enum v4l2_fwnode_location - possible device locations
> + * @V4L2_FWNODE_LOCATION_FRONT: device installed on the front side
> + * @V4L2_FWNODE_LOCATION_BACK: device installed on the back side
> + * @V4L2_FWNODE_LOCATION_EXTERNAL: device externally located
> + */
> +enum v4l2_fwnode_location {
> +	V4L2_FWNODE_LOCATION_FRONT,
> +	V4L2_FWNODE_LOCATION_BACK,
> +	V4L2_FWNODE_LOCATION_EXTERNAL
> +};
> +
> +/**
> + * struct v4l2_fwnode_device_properties - fwnode device properties
> + * @location: device location. See &enum v4l2_fwnode_location
> + * @rotation: device rotation
> + */
> +struct v4l2_fwnode_device_properties {
> +	enum v4l2_fwnode_location location;
> +	unsigned int rotation;
> +};
> +
>  /**
>   * struct v4l2_fwnode_link - a link between two endpoints
>   * @local_node: pointer to device_node of this endpoint
> @@ -233,6 +263,24 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
>   */
>  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
>  
> +/**
> + * v4l2_fwnode_device_parse() - parse fwnode device properties
> + * @dev: pointer to &struct device
> + * @props: pointer to &struct v4l2_fwnode_device_properties where to store the
> + *	   parsed properties values
> + *
> + * This function parses and validates the V4L2 fwnode device properties from
> + * the firmware interface. It is responsibility of the caller to allocate a
> + * valid @struct v4l2_fwnode_device_properties structure and provide a pointer
> + * to it in the @props parameter.
> + *
> + * Return:
> + *	% 0 on success
> + *	%-EINVAL if a parsed property value is not valid
> + */
> +int v4l2_fwnode_device_parse(struct device *dev,
> +			     struct v4l2_fwnode_device_properties *props);
> +
>  /**
>   * typedef parse_endpoint_func - Driver's callback function to be called on
>   *	each V4L2 fwnode endpoint.

-- 
Kind regards,

Sakari Ailus
sakari.ailus@linux.intel.com