Hi Jacopo,
On Fri, Nov 08, 2019 at 04:59:39PM +0100, 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@xxxxxxxxxx>
> ---
> 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;
> + 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);
> + return -EINVAL;
In both cases, you return an error back to the user if there's a problem
with the value of an optinoal property.
It could prevent probing the driver if someone screwed up the firmware
somehow, but also makes the matter more visible. I think it's good to start
with this way, and hope we don't need to change it.
> + }
> +
> + 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)
On the naming --- this is relevant for only one property at the moment, so
I'd make it specific to that property, too. This also makes it fit for the
enum below.
> +
> +/**
> + * 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.
I think the latter sentence (inserted before the leading comma of the
previous sentence) could be phrased as:
"and fills the @struct v4l2_fwnode_device_properties provided by the
caller".
> + *
> + * 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.
--
Regards,
Sakari Ailus
