Commit 159c86f3 authored by Sunil V L's avatar Sunil V L Committed by Paul Walmsley
Browse files

ACPI: Add support for nargs_prop in acpi_fwnode_get_reference_args() 



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.

Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarSunil V L <sunilvl@ventanamicro.com>
Signed-off-by: default avatarAnup Patel <apatel@ventanamicro.com>
Acked-by: default avatarJassi Brar <jassisinghbrar@gmail.com>
Link: https://lore.kernel.org/r/20250818040920.272664-16-apatel@ventanamicro.com


Signed-off-by: default avatarPaul Walmsley <pjw@kernel.org>
parent e121be78

drivers/acpi/property.c

+25 −4
Original line number Diff line number Diff line
@@ -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;

drivers/base/property.c

+1 −1
Original line number Diff line number Diff line
@@ -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.