Re: [RFC PATCH 1/3] of: base: Introduce of_alias_check_id() to check alias IDs

[Rob Herring <robh+dt@kernel.org>]

On Thu, Apr 26, 2018 at 9:08 AM, Michal Simek <michal.simek@xilinx.com> wrote:
> The function travers the lookup table to check if the request alias
> id is compatible with the device driver match structure.
> This function will be used by serial drivers to check if requested alias
> is allocated or free to use.
>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> ---
>
>  drivers/of/base.c  | 49 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of.h |  2 ++
>  2 files changed, 51 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 848f549164cd..382de01acc72 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1892,6 +1892,55 @@ int of_alias_get_id(struct device_node *np, const char *stem)
>  }
>  EXPORT_SYMBOL_GPL(of_alias_get_id);
>
> +/**
> + * of_alias_check_id - Check alias id for the give compatibility
> + * @matches:   Array of of device match structures to search in
> + * @stem:      Alias stem of the given device_node
> + * @id:                Alias ID for checking
> + *
> + * The function travers the lookup table to check if the request alias id
> + * is compatible with the device driver match structure
> + *
> + * Return true if ID is allocated, return false if not
> + */
> +bool of_alias_check_id(const struct of_device_id *matches, const char *stem,
> +                      int id)

Wouldn't it be simpler to just return a bitmap of all allocated ids
that match rather than trying to build that up 1 bit at a time?

Rob