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    Subject[PATCH v5 04/11] device property: Add functions for accessing node's parents
    Date
    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>
    ---
    drivers/base/property.c | 46 ++++++++++++++++++++++++++++++++++++++++
    include/linux/property.h | 3 +++
    2 files changed, 49 insertions(+)

    diff --git a/drivers/base/property.c b/drivers/base/property.c
    index 3d9dffbe96378..f2e555e68b56a 100644
    --- a/drivers/base/property.c
    +++ b/drivers/base/property.c
    @@ -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.
    diff --git a/include/linux/property.h b/include/linux/property.h
    index 421c76e53708d..5450e7ec219ac 100644
    --- a/include/linux/property.h
    +++ b/include/linux/property.h
    @@ -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(
    --
    2.20.1
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