Re: [PATCH v2 13/14] reset: convert reset core to using firmware nodes

[Philipp Zabel]

On Mo, 2026-02-23 at 11:06 +0100, Bartosz Golaszewski wrote:
> With everything else now in place, we can convert the remaining parts of
> the reset subsystem to becoming fwnode-agnostic - meaning it will work
> with all kinds of firmware nodes, not only devicetree.
> 
> To that end: extend struct reset_controller_dev with fields taking
> information relevant for using firmware nodes (which mirrors what we
> already do for OF-nodes) and limit using of_ APIs only to where it's
> absolutely necessary (mostly around the of_xlate callback).
> 
> For backward compatibility of existing drivers we still support OF-nodes
> but firmware nodes become the preferred method.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
> ---
>  drivers/reset/core.c             | 154 +++++++++++++++++++++++----------------
>  include/linux/reset-controller.h |  14 +++-
>  2 files changed, 103 insertions(+), 65 deletions(-)
> 
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index 1ac68371b77101b18db5a16c6471cfffee0dce7c..174b50eda01948bc697529a549cf38bfca7180f8 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
> @@ -81,13 +81,13 @@ struct reset_control_array {
>  
>  /**
>   * struct reset_gpio_lookup - lookup key for ad-hoc created reset-gpio devices
> - * @of_args: phandle to the reset controller with all the args like GPIO number
> + * @ref_args: Reference to the reset controller with all the args like GPIO number
>   * @swnode: Software node containing the reference to the GPIO provider
>   * @list: list entry for the reset_gpio_lookup_list
>   * @adev: Auxiliary device representing the reset controller
>   */
>  struct reset_gpio_lookup {
> -	struct of_phandle_args of_args;
> +	struct fwnode_reference_args ref_args;
>  	struct fwnode_handle *swnode;
>  	struct list_head list;
>  	struct auxiliary_device adev;
> @@ -98,24 +98,24 @@ static const char *rcdev_name(struct reset_controller_dev *rcdev)
>  	if (rcdev->dev)
>  		return dev_name(rcdev->dev);
>  
> -	if (rcdev->of_node)
> -		return rcdev->of_node->full_name;
> +	if (rcdev->fwnode)
> +		return fwnode_get_name(rcdev->fwnode);
>  
>  	return NULL;
>  }
>  
>  /**
> - * of_reset_simple_xlate - translate reset_spec to the reset line number
> + * fwnode_reset_simple_xlate - translate reset_spec to the reset line number
>   * @rcdev: a pointer to the reset controller device
> - * @reset_spec: reset line specifier as found in the device tree
> + * @reset_spec: reset line specifier as found in firmware
>   *
> - * This static translation function is used by default if of_xlate in
> + * This static translation function is used by default if fwnode_xlate in

... if neither fwnode_xlate nor of_xlate ... are set.

>   * :c:type:`reset_controller_dev` is not set. It is useful for all reset
>   * controllers with 1:1 mapping, where reset lines can be indexed by number
>   * without gaps.
>   */
> -static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
> -				 const struct of_phandle_args *reset_spec)
> +static int fwnode_reset_simple_xlate(struct reset_controller_dev *rcdev,
> +				     const struct fwnode_reference_args *reset_spec)
>  {
>  	if (reset_spec->args[0] >= rcdev->nr_resets)
>  		return -EINVAL;
> @@ -129,9 +129,17 @@ static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
>   */
>  int reset_controller_register(struct reset_controller_dev *rcdev)
>  {
> -	if (!rcdev->of_xlate) {
> -		rcdev->of_reset_n_cells = 1;
> -		rcdev->of_xlate = of_reset_simple_xlate;
> +	if ((rcdev->of_node && rcdev->fwnode) || (rcdev->of_xlate && rcdev->fwnode_xlate))
> +		return -EINVAL;
> +
> +	if (rcdev->of_node) {
> +		rcdev->fwnode = of_fwnode_handle(rcdev->of_node);
> +		rcdev->fwnode_reset_n_cells = rcdev->of_reset_n_cells;
> +	}
> +
> +	if (rcdev->fwnode && !rcdev->fwnode_xlate) {
> +		rcdev->fwnode_reset_n_cells = 1;
> +		rcdev->fwnode_xlate = fwnode_reset_simple_xlate;

There should be no driver that does this, but if neither of_node nor
fwnode are set, this can leave fwnode_xlate == NULL and cause
reset_control_get() to always return -EINVAL. We could return -EINVAL
here if (!rcdev->of_node != !rcdev->fwnode).

regards
Philipp