Re: [XEN][PATCH v10 08/20] xen/device-tree: Add device_tree_find_node_by_path() to find nodes in device tree

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 25 Aug 2023, Vikram Garhwal wrote:
> Add device_tree_find_node_by_path() to find a matching node with path for a
> dt_device_node.
> 
> Reason behind this function:
>     Each time overlay nodes are added using .dtbo, a new fdt(memcpy of
>     device_tree_flattened) is created and updated with overlay nodes. This
>     updated fdt is further unflattened to a dt_host_new. Next, we need to find
>     the overlay nodes in dt_host_new, find the overlay node's parent in 
> dt_host
>     and add the nodes as child under their parent in the dt_host. Thus we need
>     this function to search for node in different unflattened device trees.
> 
> Also, make dt_find_node_by_path() static inline.
> 
> Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes from v9:
>     Fix indentation issues.
> 
> Changes from v7:
>     Rename device_tree_find_node_by_path() to dt_find_node_by_path_from().
>     Fix indentation.
> ---
> ---
>  xen/common/device_tree.c      |  5 +++--
>  xen/include/xen/device_tree.h | 17 +++++++++++++++--
>  2 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index b8ef1c7ae2..f38f51ec0b 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -358,11 +358,12 @@ struct dt_device_node *dt_find_node_by_type(struct 
> dt_device_node *from,
>      return np;
>  }
>  
> -struct dt_device_node *dt_find_node_by_path(const char *path)
> +struct dt_device_node *dt_find_node_by_path_from(struct dt_device_node *from,
> +                                                 const char *path)
>  {
>      struct dt_device_node *np;
>  
> -    dt_for_each_device_node(dt_host, np)
> +    dt_for_each_device_node(from, np)
>          if ( np->full_name && (dt_node_cmp(np->full_name, path) == 0) )
>              break;
>  
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index a518310a62..44d315c8ba 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -570,13 +570,26 @@ struct dt_device_node *dt_find_node_by_type(struct 
> dt_device_node *from,
>  struct dt_device_node *dt_find_node_by_alias(const char *alias);
>  
>  /**
> - * dt_find_node_by_path - Find a node matching a full DT path
> + * dt_find_node_by_path_from - Generic function to find a node matching the
> + * full DT path for any given unflatten device tree
> + * @from: The device tree node to start searching from
>   * @path: The full path to match
>   *
>   * Returns a node pointer.
>   */
> -struct dt_device_node *dt_find_node_by_path(const char *path);
> +struct dt_device_node *dt_find_node_by_path_from(struct dt_device_node *from,
> +                                                 const char *path);
>  
> +/**
> + * dt_find_node_by_path - Find a node matching a full DT path in dt_host
> + * @path: The full path to match
> + *
> + * Returns a node pointer.
> + */
> +static inline struct dt_device_node *dt_find_node_by_path(const char *path)
> +{
> +    return dt_find_node_by_path_from(dt_host, path);
> +}
>  
>  /**
>   * dt_find_node_by_gpath - Same as dt_find_node_by_path but retrieve the
> -- 
> 2.17.1
>