Re: [Xen-devel] [PATCH V1 1/2] xen/device-tree: Add dt_count_phandle_with_args helper

[Julien Grall <julien.grall@xxxxxxx>]

Hi Oleksandr,

On 21/05/2019 18:37, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
>
> Port Linux helper of_count_phandle_with_args for counting
> number of phandles in a property.
>
> Please note, this helper is ported from Linux v4.6.
>
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
>      Changes RFC -> V1:
>          - Add Linux version which is used as the base.
> ---
>   xen/common/device_tree.c      |  7 +++++++
>   xen/include/xen/device_tree.h | 19 +++++++++++++++++++
>   2 files changed, 26 insertions(+)
>
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 8fc401d..65862b5 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -1663,6 +1663,13 @@ int dt_parse_phandle_with_args(const struct 
> dt_device_node *np,
>                                           index, out_args);
>   }
>   
> +int dt_count_phandle_with_args(const struct dt_device_node *np,
> +                               const char *list_name,
> +                               const char *cells_name)
> +{
> +    return __dt_parse_phandle_with_args(np, list_name, cells_name, 0, -1, 
> NULL);
> +}
> +
>   /**
>    * unflatten_dt_node - Alloc and populate a device_node from the flat tree
>    * @fdt: The parent device tree blob
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index 7408a6c..8315629 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -738,6 +738,25 @@ int dt_parse_phandle_with_args(const struct dt_device_node 
> *np,
>                                  const char *cells_name, int index,
>                                  struct dt_phandle_args *out_args);
>   
> +/**
> + * dt_count_phandle_with_args() - Find the number of phandles references in a 
> property
> + * @np: pointer to a device tree node containing a list
> + * @list_name: property name that contains a list
> + * @cells_name: property name that specifies phandles' arguments count
> + *
> + * Returns the number of phandle + argument tuples within a property. It
> + * is a typical pattern to encode a list of phandle and variable
> + * arguments into a single property. The number of arguments is encoded
> + * by a property in the phandle-target node. For example, a gpios
> + * property would contain a list of GPIO specifies consisting of a
> + * phandle and 1 or more arguments. The number of arguments are
> + * determined by the #gpio-cells property in the node pointed to by the
> + * phandle.
> + */
> +int dt_count_phandle_with_args(const struct dt_device_node *np,
> +                               const char *list_name,
> +                               const char *cells_name);
> +
>   #ifdef CONFIG_DEVICE_TREE_DEBUG
>   #define dt_dprintk(fmt, args...)  \
>       printk(XENLOG_DEBUG fmt, ## args)
--
Julien Grall

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