[PATCH 1/2] of: Add helper to lookup non port child node

[Rob Herring]

On Mon, Dec 6, 2021 at 11:49 PM Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> Add of_get_non_port_child() helper that can be used to lookup
> non port child nodes.
>
> Some OF graphs don't require 'ports' to represent the next output
> instead, it simply adds a child node on a given parent node. This
> helper lookup that child node, however that child node is not a
> 'port' on given parent as 'port' based nodes are looked up via
> of_graph_get_remote_node().
>
> Example OF graph representation of DSI host, which doesn't
> have 'ports'.

This seems pretty specific to DSI and also can't handle there being
more than 1 non-port node. That's allowed for DSI too, but I don't
think I've ever seen a case. Anyways, I'd just move this to DRM rather
than common DT code. One comment on the implementation that will
shrink it.

>
> dsi {
>         #address-cells = <1>;
>         #size-cells = <0>;
>
>         port {
>                 dsi_in_tcon0: endpoint {
>                         remote-endpoint = <tcon0_out_dsi>;
>         };
>
>         panel at 0 {
>                 reg = <0>;
>         };
> };
>
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> ---
>  drivers/of/base.c  | 29 +++++++++++++++++++++++++++++
>  include/linux/of.h |  6 ++++++
>  2 files changed, 35 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 61de453b885c..31bbf885b0f8 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -854,6 +854,35 @@ struct device_node *of_get_compatible_child(const struct device_node *parent,
>  }
>  EXPORT_SYMBOL(of_get_compatible_child);
>
> +/**
> + * of_get_non_port_child - Find the non port child node for a given parent
> + * @node:      parent node
> + *
> + * This function looks for child node which is not port child for given parent.
> + *
> + * Return: A node pointer if found, with refcount incremented, use
> + * of_node_put() on it when done.
> + * Returns NULL if node is not found.
> + */
> +struct device_node *of_get_non_port_child(const struct device_node *parent)
> +{
> +       struct device_node *child;
> +
> +       for_each_child_of_node(parent, child) {

for_each_available_child_of_node

> +               if (of_node_name_eq(child, "port"))
> +                       continue;
> +
> +               if (!of_device_is_available(child)) {
> +                       of_node_put(child);
> +                       continue;
> +               }
> +               break;
> +       }
> +
> +       return child;
> +}
> +EXPORT_SYMBOL(of_get_non_port_child);
> +
>  /**
>   * of_get_child_by_name - Find the child node by name for a given parent
>   * @node:      parent node
> diff --git a/include/linux/of.h b/include/linux/of.h
> index ff143a027abc..3e699becef82 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -290,6 +290,7 @@ extern struct device_node *of_get_next_child(const struct device_node *node,
>  extern struct device_node *of_get_next_available_child(
>         const struct device_node *node, struct device_node *prev);
>
> +extern struct device_node *of_get_non_port_child(const struct device_node *parent);
>  extern struct device_node *of_get_compatible_child(const struct device_node *parent,
>                                         const char *compatible);
>  extern struct device_node *of_get_child_by_name(const struct device_node *node,
> @@ -678,6 +679,11 @@ static inline bool of_have_populated_dt(void)
>         return false;
>  }
>
> +static inline struct device_node *of_get_non_port_child(const struct device_node *parent)
> +{
> +       return NULL;
> +}
> +
>  static inline struct device_node *of_get_compatible_child(const struct device_node *parent,
>                                         const char *compatible)
>  {
> --
> 2.25.1
>