Re: [PATCH 3.6.0-rc5] dt: introduce of_get_child to get child node by name.

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 09/13/2012 06:10 AM, Srinivas KANDAGATLA wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla-qxv4g6HH51o@public.gmane.org>
> 
> This patch introduces of_get_child function to get a child node by its
> name in a given parent node.
> 
> Without this patch each driver code has to iterate the parent and do
> a string compare, However having of_get_child libary function would
> avoid code duplication, errors and is more convenient.
> 
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla-qxv4g6HH51o@public.gmane.org>
> ---
>  drivers/of/base.c  |   27 +++++++++++++++++++++++++++
>  include/linux/of.h |    2 ++
>  2 files changed, 29 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d4a1c9a..d4b6840 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -391,6 +391,33 @@ struct device_node *of_get_next_available_child(const struct device_node *node,
>  EXPORT_SYMBOL(of_get_next_available_child);
>  
>  /**
> + *	of_get_child - Find the child node by name for given parent
> + *	@node:	parent node
> + *	@name:	child name to look for.
> + *
> + *      This function looks for child node for given matching name
> + *
> + *	Returns a node pointer if found, with refcount incremented, use
> + *	of_node_put() on it when done.
> + *	else returns NULL.
> + */
> +
> +struct device_node *of_get_child(const struct device_node *node,

of_get_child_by_name would be more consistent naming with other apis.

> +				const char *name)
> +{
> +	struct device_node *child;
> +
> +	read_lock(&devtree_lock);

I don't think you need the lock here. The for_each takes the lock while
finding the node.

> +	for_each_child_of_node(node, child)
> +		if (child->name && (of_node_cmp(child->name, name) == 0)
> +			&& of_node_get(child))
> +			break;
> +	read_unlock(&devtree_lock);
> +	return child;
> +}
> +EXPORT_SYMBOL(of_get_child);
> +
> +/**
>   *	of_find_node_by_path - Find a node matching a full OF path
>   *	@path:	The full path to match
>   *
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 1b11632..510e1fe 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -192,6 +192,8 @@ extern struct device_node *of_get_next_child(const struct device_node *node,
>  					     struct device_node *prev);
>  extern struct device_node *of_get_next_available_child(
>  	const struct device_node *node, struct device_node *prev);
> +extern struct device_node *of_get_child(const struct device_node *node,
> +					const char *name);
>  
>  #define for_each_child_of_node(parent, child) \
>  	for (child = of_get_next_child(parent, NULL); child != NULL; \
>