From 4ec0a44ba8d797876ff416fc0317a0169483d240 Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Wed, 1 Jul 2020 10:42:31 +0300 Subject: of_graph: add of_graph_is_present() 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 Signed-off-by: Dmitry Osipenko Reviewed-by: Laurent Pinchart Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20200701074232.13632-2-digetx@gmail.com --- drivers/of/property.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'drivers/of') diff --git a/drivers/of/property.c b/drivers/of/property.c index 1f2086f4e7ce..d3f9fb98e882 100644 --- a/drivers/of/property.c +++ b/drivers/of/property.c @@ -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 * -- cgit v1.2.3