On Fri, Jul 4, 2025 at 9:07 AM Anup Patel <apatel@xxxxxxxxxxxxxxxx> wrote:
>
> From: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
>
> Currently, ACPI does not support the use of a nargs_prop (e.g.,
> associated with a reference in fwnode_property_get_reference_args().
> Instead, ACPI expects the number of arguments (nargs) to be explicitly
> passed or known.
>
> This behavior diverges from Open Firmware (OF), which allows the use of
> a #*-cells property in the referenced node to determine the number of
> arguments. Since fwnode_property_get_reference_args() is a common
> interface used across both OF and ACPI firmware paradigms, it is
> desirable to have a unified calling convention that works seamlessly for
> both.
>
> Add the support for ACPI to parse a nargs_prop from the referenced
> fwnode, aligning its behavior with the OF backend. This allows drivers
> and subsystems using fwnode_property_get_reference_args() to work in a
> firmware-agnostic way without having to hardcode or special-case
> argument counts for ACPI.
>
> Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
LGTM now, so
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/acpi/property.c | 29 +++++++++++++++++++++++++----
> drivers/base/property.c | 2 +-
> 2 files changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index d4863746fb11..e92402deee77 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -804,13 +804,35 @@ acpi_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
> return NULL;
> }
>
> +static unsigned int acpi_fwnode_get_args_count(struct fwnode_handle *fwnode,
> + const char *nargs_prop)
> +{
> + const struct acpi_device_data *data;
> + const union acpi_object *obj;
> + int ret;
> +
> + data = acpi_device_data_of_node(fwnode);
> + if (!data)
> + return 0;
> +
> + ret = acpi_data_get_property(data, nargs_prop, ACPI_TYPE_INTEGER, &obj);
> + if (ret)
> + return 0;
> +
> + return obj->integer.value;
> +}
> +
> static int acpi_get_ref_args(struct fwnode_reference_args *args,
> struct fwnode_handle *ref_fwnode,
> + const char *nargs_prop,
> const union acpi_object **element,
> const union acpi_object *end, size_t num_args)
> {
> u32 nargs = 0, i;
>
> + if (nargs_prop)
> + num_args = acpi_fwnode_get_args_count(ref_fwnode, nargs_prop);
> +
> /*
> * Assume the following integer elements are all args. Stop counting on
> * the first reference (possibly represented as a string) or end of the
> @@ -961,10 +983,10 @@ static int acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
> return -EINVAL;
>
> element++;
> -
> ret = acpi_get_ref_args(idx == index ? args : NULL,
> acpi_fwnode_handle(device),
> - &element, end, args_count);
> + nargs_prop, &element, end,
> + args_count);
> if (ret < 0)
> return ret;
>
> @@ -979,9 +1001,8 @@ static int acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
> return -EINVAL;
>
> element++;
> -
> ret = acpi_get_ref_args(idx == index ? args : NULL,
> - ref_fwnode, &element, end,
> + ref_fwnode, nargs_prop, &element, end,
> args_count);
> if (ret < 0)
> return ret;
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index f626d5bbe806..6a63860579dd 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -578,7 +578,7 @@ EXPORT_SYMBOL_GPL(fwnode_property_match_property_string);
> * @prop: The name of the property
> * @nargs_prop: The name of the property telling the number of
> * arguments in the referred node. NULL if @nargs is known,
> - * otherwise @nargs is ignored. Only relevant on OF.
> + * otherwise @nargs is ignored.
> * @nargs: Number of arguments. Ignored if @nargs_prop is non-NULL.
> * @index: Index of the reference, from zero onwards.
> * @args: Result structure with reference and integer arguments.
> --
> 2.43.0
>
