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device property: Add functions for accessing node's parents 

Add two convenience functions for accessing node's parents:

fwnode_count_parents() returns the number of parent nodes a given node
has. fwnode_get_nth_parent() returns node's parent at a given distance
from the node itself.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Sakari Ailus 2019-10-03 15:32:11 +03:00 committed by Rafael J. Wysocki
parent a57b7fb783
commit 87e5e95db3
2 changed files with 49 additions and 0 deletions
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46
drivers/base/property.c
View File

@ -590,6 +590,52 @@ struct fwnode_handle *fwnode_get_next_parent(struct fwnode_handle *fwnode)
}
EXPORT_SYMBOL_GPL(fwnode_get_next_parent);
/**
* fwnode_count_parents - Return the number of parents a node has
* @fwnode: The node the parents of which are to be counted
*
* Returns the number of parents a node has.
*/
unsigned int fwnode_count_parents(const struct fwnode_handle *fwnode)
{
struct fwnode_handle *__fwnode;
unsigned int count;
__fwnode = fwnode_get_parent(fwnode);
for (count = 0; __fwnode; count++)
__fwnode = fwnode_get_next_parent(__fwnode);
return count;
}
EXPORT_SYMBOL_GPL(fwnode_count_parents);
/**
* fwnode_get_nth_parent - Return an nth parent of a node
* @fwnode: The node the parent of which is requested
* @depth: Distance of the parent from the node
*
* Returns the nth parent of a node. If there is no parent at the requested
* @depth, %NULL is returned. If @depth is 0, the functionality is equivalent to
* fwnode_handle_get(). For @depth == 1, it is fwnode_get_parent() and so on.
*
* The caller is responsible for calling fwnode_handle_put() for the returned
* node.
*/
struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwnode,
unsigned int depth)
{
unsigned int i;
fwnode_handle_get(fwnode);
for (i = 0; i < depth && fwnode; i++)
fwnode = fwnode_get_next_parent(fwnode);
return fwnode;
}
EXPORT_SYMBOL_GPL(fwnode_get_nth_parent);
/**
* fwnode_get_next_child_node - Return the next child node handle for a node
* @fwnode: Firmware node to find the next child node for.

3
include/linux/property.h
View File

@ -83,6 +83,9 @@ struct fwnode_handle *fwnode_find_reference(const struct fwnode_handle *fwnode,
struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
struct fwnode_handle *fwnode_get_next_parent(
struct fwnode_handle *fwnode);
unsigned int fwnode_count_parents(const struct fwnode_handle *fwn);
struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwn,
unsigned int depth);
struct fwnode_handle *fwnode_get_next_child_node(
const struct fwnode_handle *fwnode, struct fwnode_handle *child);
struct fwnode_handle *fwnode_get_next_available_child_node(