Re: [Xen-devel] [RFC PATCH 11/31] xen/device-tree: Add dt_property_count_elems_of_size helper

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 9 Nov 2017, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> 
> This is a port from Linux.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxxxxx>

Same here

> ---
>  xen/common/device_tree.c      | 20 ++++++++++++++++++++
>  xen/include/xen/device_tree.h | 15 +++++++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 0fa654e..7b4cad3 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -278,6 +278,26 @@ const char *dt_property_next_string(const struct 
> dt_property *prop,
>      return curv;
>  }
>  
> +int dt_property_count_elems_of_size(const struct dt_device_node *np,
> +                                    const char *propname, int elem_size)
> +{
> +    const struct dt_property *prop = dt_find_property(np, propname, NULL);
> +
> +    if ( !prop )
> +        return -EINVAL;
> +    if ( !prop->value )
> +        return -ENODATA;
> +
> +    if ( prop->length % elem_size != 0 )
> +    {
> +        printk("%s: size of %s is not a multiple of %d\n", np->full_name,
> +               propname, elem_size);
> +        return -EINVAL;
> +    }
> +
> +    return prop->length / elem_size;
> +}
> +
>  bool_t dt_device_is_compatible(const struct dt_device_node *device,
>                                 const char *compat)
>  {
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index 87b4b67..e2d7346 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -461,6 +461,21 @@ const char *dt_property_next_string(const struct 
> dt_property *prop,
>          s = dt_property_next_string(prop, s))
>  
>  /**
> + * dt_property_count_elems_of_size - Count the number of elements in a 
> property
> + *
> + * @np:        device node from which the property value is to be read.
> + * @propname:  name of the property to be searched.
> + * @elem_size: size of the individual element
> + *
> + * Search for a property in a device node and count the number of elements of
> + * size elem_size in it. Returns number of elements on sucess, -EINVAL if the
> + * property does not exist or its length does not match a multiple of 
> elem_size
> + * and -ENODATA if the property does not have a value.
> + */
> +int dt_property_count_elems_of_size(const struct dt_device_node *np,
> +                                    const char *propname, int elem_size);
> +
> +/**
>   * Checks if the given "compat" string matches one of the strings in
>   * the device's "compatible" property
>   */
> -- 
> 2.7.4
> 

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