Re: [PATCH] of: add helper for getting endpoint node with specific identifiers

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, Feb 16, 2015 at 4:37 AM, Hyungwon Hwang <human.hwang-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> wrote:
> When there are multiple ports or multiple endpoints in a port, they have to be
> distinguished by the value of reg property. It is common. The drivers can get
> the specific endpoint in the specific port via this function. Now the drivers
> have to implement this code in themselves or have to force the order of dt nodes
> to get the right node.
>
> Signed-off-by: Hyungwon Hwang <human.hwang-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> ---
>  drivers/of/base.c        | 34 ++++++++++++++++++++++++++++++++++
>  include/linux/of_graph.h |  2 ++
>  2 files changed, 36 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 36536b6..95ffe1c 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2155,6 +2155,40 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
>  EXPORT_SYMBOL(of_graph_get_next_endpoint);
>
>  /**
> + * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
> + * @parent: pointer to the parent device node
> + * @port_reg: identifier (value of reg property) of the parent port node
> + * @reg: identifier (value of reg property) of the endpoint node
> + *
> + * Return: An 'endpoint' node pointer which is identified by reg and at the same
> + * is the child of a port node identified by port_reg. reg and port_reg are
> + * ignored when they are -1.
> + */
> +struct device_node *of_graph_get_endpoint_by_regs(
> +       const struct device_node *parent, int port_reg, int reg)
> +{
> +       struct of_endpoint endpoint;
> +       struct device_node *node, *prev_node = NULL;
> +
> +       while (1) {
> +               node = of_graph_get_next_endpoint(parent, prev_node);
> +               of_node_put(prev_node);
> +               if (!node)
> +                       break;
> +
> +               of_graph_parse_endpoint(node, &endpoint);

Seems like this all could be in a "for_each_of_graph_child_endpoint"
iterator. I've not looked, but I'd guess there are other similar
loops?

> +               if (((port_reg == -1) ||

What if of_graph_parse_endpoint failed?

> +                       (endpoint.port == (unsigned int) port_reg)) &&
> +                       ((reg == -1) || (endpoint.id == (unsigned int) reg)))

Why the casts?

> +                       return node;
> +
> +               prev_node = node;
> +       }
> +
> +       return NULL;
> +}
> +
> +/**
>   * of_graph_get_remote_port_parent() - get remote port's parent node
>   * @node: pointer to a local endpoint device_node
>   *
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index befef42..c119728 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -31,6 +31,8 @@ int of_graph_parse_endpoint(const struct device_node *node,
>                                 struct of_endpoint *endpoint);
>  struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
>                                         struct device_node *previous);
> +struct device_node *of_graph_get_endpoint_by_regs(
> +               const struct device_node *parent, int port_reg, int reg);

Empty version is needed.

>  struct device_node *of_graph_get_remote_port_parent(
>                                         const struct device_node *node);
>  struct device_node *of_graph_get_remote_port(const struct device_node *node);
> --
> 1.9.1
>
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