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of_graph: add of_graph_is_present()

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In some cases it's very useful to silently check whether port node exists
at all in a device-tree before proceeding with parsing the graph. The DRM
bridges code is one example of such case where absence of a graph in a
device-tree is a legit condition.

This patch adds of_graph_is_present() which returns true if given
device-tree node contains OF graph port.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701074232.13632-2-digetx@gmail.com
This commit is contained in:
Dmitry Osipenko 2020-07-01 10:42:31 +03:00 committed by Sam Ravnborg
parent 1185c406f1
commit 4ec0a44ba8
2 changed files with 29 additions and 0 deletions
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23
drivers/of/property.c
View File

@ -29,6 +29,29 @@
#include "of_private.h"
/**
* of_graph_is_present() - check graph's presence
* @node: pointer to device_node containing graph port
*
* Return: True if @node has a port or ports (with a port) sub-node,
* false otherwise.
*/
bool of_graph_is_present(const struct device_node *node)
{
struct device_node *ports, *port;
ports = of_get_child_by_name(node, "ports");
if (ports)
node = ports;
port = of_get_child_by_name(node, "port");
of_node_put(ports);
of_node_put(port);
return !!port;
}
EXPORT_SYMBOL(of_graph_is_present);
/**
* of_property_count_elems_of_size - Count the number of elements in a property
*

6
include/linux/of_graph.h
View File

@ -38,6 +38,7 @@ struct of_endpoint {
child = of_graph_get_next_endpoint(parent, child))
#ifdef CONFIG_OF
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_endpoint_count(const struct device_node *np);
@ -56,6 +57,11 @@ struct device_node *of_graph_get_remote_node(const struct device_node *node,
u32 port, u32 endpoint);
#else
static inline bool of_graph_is_present(const struct device_node *node)
{
return false;
}
static inline int of_graph_parse_endpoint(const struct device_node *node,
struct of_endpoint *endpoint)
{