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Date: Wed, 13 Jan 2021 19:10:41 -0600
From: Rob Herring <robh+dt@...nel.org>
To: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Cc: Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] of: property: add port base loop
On Wed, Jan 13, 2021 at 12:53 AM Kuninori Morimoto
<kuninori.morimoto.gx@...esas.com> wrote:
>
>
> From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
>
> We have endpoint base functions
> - of_graph_get_next_endpoint()
> - of_graph_get_endpoint_count()
> - for_each_endpoint_of_node()
I actually think these functions don't make sense. Iterating over
endpoints for a port make sense, but not all endpoints.
> Here, for_each_endpoint_of_node() loop finds endpoint
>
> ports {
> port@0 {
> (1) endpoint {...};
> };
> port@1 {
> (2) endpoint {...};
> };
> ...
> };
>
> In above case, for_each_endpoint_of_node() loop
> finds endpoint as (1) -> (2) -> ...
> We can check endpoint parent to get its port
> if user want to do something to it.
>
> But port can have multi endpoints.
> In such case, it is difficult to find
> port@0 -> port@1 -> ...
>
> ports {
> port@0 {
> (1) endpoint@0 {...};
> (2) endpoint@1 {...};
> };
> port@1 {
> (3) endpoint {...};
> };
> ...
> };
>
> In such case, people want to have port base loop
> instead of endpoints base loop.
> This patch adds such functions/macros.
I'm a bit hesitant on these too. A driver should generally know what
each port # is (since the binding has to define them), and it should
just request the port (or its connection) it wants. At least that was
the premise behind of_graph_get_remote_node() and the cleanups (mostly
DRM drivers) I did to use it. I'd rather see things move in that
direction.
In any case, this needs a user before merging.
>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
> ---
> drivers/of/property.c | 69 ++++++++++++++++++++++++++++++++++------
> include/linux/of_graph.h | 14 ++++++++
> 2 files changed, 73 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 5f9eed79a8aa..9b511cfe97b3 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -631,15 +631,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
> * parent port node.
> */
> if (!prev) {
> - struct device_node *node;
> -
> - node = of_get_child_by_name(parent, "ports");
> - if (node)
> - parent = node;
> -
> - port = of_get_child_by_name(parent, "port");
> - of_node_put(node);
> -
> + port = of_graph_get_next_port(parent, NULL);
> if (!port) {
> pr_err("graph: no port node found in %pOF\n", parent);
> return NULL;
> @@ -666,14 +658,59 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
> /* No more endpoints under this port, try the next one. */
> prev = NULL;
>
> + port = of_graph_get_next_port(parent, port);
> + if (!port)
> + return NULL;
> + }
> +}
> +EXPORT_SYMBOL(of_graph_get_next_endpoint);
> +
> +/**
> + * of_graph_get_next_port() - get next port node
> + * @parent: pointer to the parent device node
> + * @prev: previous port node, or NULL to get first
> + *
> + * Return: An 'port' node pointer with refcount incremented. Refcount
> + * of the passed @prev node is decremented.
> + */
> +struct device_node *of_graph_get_next_port(const struct device_node *parent,
> + struct device_node *prev)
> +{
> + struct device_node *port = prev;
> +
> + if (!parent)
> + return NULL;
> +
> + /*
> + * Start by locating the port node. If no previous endpoint is specified
> + * search for the first port node, otherwise get the previous endpoint
> + * parent port node.
> + */
> + if (!port) {
> + struct device_node *node;
> +
> + node = of_get_child_by_name(parent, "ports");
> + if (node)
> + parent = node;
> +
> + port = of_get_child_by_name(parent, "port");
> + of_node_put(node);
> +
> + if (!port) {
> + pr_err("graph: no port node found in %pOF\n", parent);
> + return NULL;
> + }
> + } else {
> do {
> port = of_get_next_child(parent, port);
> if (!port)
> return NULL;
> } while (!of_node_name_eq(port, "port"));
> }
> +
> + return port;
> }
> -EXPORT_SYMBOL(of_graph_get_next_endpoint);
> +EXPORT_SYMBOL(of_graph_get_next_port);
>
> /**
> * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
> @@ -800,6 +837,18 @@ int of_graph_get_endpoint_count(const struct device_node *np)
> }
> EXPORT_SYMBOL(of_graph_get_endpoint_count);
>
> +int of_graph_get_port_count(const struct device_node *np)
> +{
> + struct device_node *port;
> + int num = 0;
> +
> + for_each_port_of_node(np, port)
> + num++;
> +
> + return num;
> +}
> +EXPORT_SYMBOL(of_graph_get_port_count);
> +
> /**
> * of_graph_get_remote_node() - get remote parent device_node for given port/endpoint
> * @node: pointer to parent device_node containing graph port/endpoint
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index 4d7756087b6b..8cd3bd674ebd 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -26,6 +26,17 @@ struct of_endpoint {
> const struct device_node *local_node;
> };
>
> +/**
> + * for_each_port_of_node - iterate over every port in a device node
> + * @parent: parent device node containing ports and port
> + * @child: loop variable pointing to the current port node
> + *
> + * When breaking out of the loop, of_node_put(child) has to be called manually.
> + */
> +#define for_each_port_of_node(parent, child) \
> + for (child = of_graph_get_next_port(parent, NULL); child != NULL; \
> + child = of_graph_get_next_port(parent, child))
> +
> /**
> * for_each_endpoint_of_node - iterate over every endpoint in a device node
> * @parent: parent device node containing ports and endpoints
> @@ -41,8 +52,11 @@ struct of_endpoint {
> bool of_graph_is_present(const struct device_node *node);
> int of_graph_parse_endpoint(const struct device_node *node,
> struct of_endpoint *endpoint);
> +int of_graph_get_port_count(const struct device_node *np);
> int of_graph_get_endpoint_count(const struct device_node *np);
> struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
> +struct device_node *of_graph_get_next_port(const struct device_node *parent,
> + struct device_node *previous);
> 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(
> --
> 2.25.1
>
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