Re: [PATCH v4 06/11] xen/device-tree: Add dt_property_match_string helper

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 8 Jan 2021, Rahul Singh wrote:
> Import the Linux helper of_property_match_string. This function searches
> a string list property and returns the index of a specific string value.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes in V3:
>  - This patch is introduce in this verison.
> Changes in V4: Rebase
> ---
>  xen/common/device_tree.c      | 27 +++++++++++++++++++++++++++
>  xen/include/xen/device_tree.h | 12 ++++++++++++
>  2 files changed, 39 insertions(+)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index e107c6f89f..18825e333e 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -208,6 +208,33 @@ int dt_property_read_string(const struct dt_device_node 
> *np,
>      return 0;
>  }
>  
> +int dt_property_match_string(const struct dt_device_node *np,
> +                             const char *propname, const char *string)
> +{
> +    const struct dt_property *dtprop = dt_find_property(np, propname, NULL);
> +    size_t l;
> +    int i;
> +    const char *p, *end;
> +
> +    if ( !dtprop )
> +        return -EINVAL;
> +    if ( !dtprop->value )
> +        return -ENODATA;
> +
> +    p = dtprop->value;
> +    end = p + dtprop->length;
> +
> +    for ( i = 0; p < end; i++, p += l )
> +    {
> +        l = strnlen(p, end - p) + 1;
> +        if ( p + l > end )
> +            return -EILSEQ;
> +        if ( strcmp(string, p) == 0 )
> +            return i; /* Found it; return index */
> +    }
> +    return -ENODATA;
> +}
> +
>  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 f2ad22b79c..b02696be94 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -400,6 +400,18 @@ static inline bool_t dt_property_read_bool(const struct 
> dt_device_node *np,
>  int dt_property_read_string(const struct dt_device_node *np,
>                              const char *propname, const char **out_string);
>  
> +/**
> + * dt_property_match_string() - Find string in a list and return index
> + * @np: pointer to node containing string list property
> + * @propname: string list property name
> + * @string: pointer to string to search for in string list
> + *
> + * This function searches a string list property and returns the index
> + * of a specific string value.
> + */
> +int dt_property_match_string(const struct dt_device_node *np,
> +                             const char *propname, const char *string);
> +
>  /**
>   * Checks if the given "compat" string matches one of the strings in
>   * the device's "compatible" property
> -- 
> 2.17.1
>