linux-kernel - [PATCH v4 15/23] ACPI: property: Add support for cells property

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Message-ID: <20250525084710.1665648-16-apatel@ventanamicro.com>
Date: Sun, 25 May 2025 14:17:02 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Uwe Kleine-König <ukleinek@...nel.org>
Cc: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Len Brown <lenb@...nel.org>,
	Sunil V L <sunilvl@...tanamicro.com>,
	Rahul Pathak <rpathak@...tanamicro.com>,
	Leyfoon Tan <leyfoon.tan@...rfivetech.com>,
	Atish Patra <atish.patra@...ux.dev>,
	Andrew Jones <ajones@...tanamicro.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Anup Patel <anup@...infault.org>,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 15/23] ACPI: property: Add support for cells property

From: Sunil V L <sunilvl@...tanamicro.com>

Currently, ACPI doesn't support cells property when
fwnode_property_get_reference_args() is called. ACPI always expects
the number of arguments to be passed. However, the above mentioned
call being a common interface for OF and ACPI, it is better to have
single calling convention which works for both. Hence, add support
for cells property on the reference device to get the number of
arguments dynamically.

Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
---
 drivers/acpi/property.c | 22 ++++++++++++++++++++++
 drivers/base/property.c |  2 +-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index d4863746fb11..c9c3d6920326 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -882,6 +882,20 @@ static struct fwnode_handle *acpi_parse_string_ref(const struct fwnode_handle *f
 	return &dn->fwnode;
 }
 
+static unsigned int acpi_fwnode_get_args_count(const struct acpi_device *device,
+					       const char *nargs_prop)
+{
+	const union acpi_object *obj;
+
+	if (!nargs_prop)
+		return 0;
+
+	if (acpi_dev_get_property(device, nargs_prop, ACPI_TYPE_INTEGER, &obj))
+		return 0;
+
+	return obj->integer.value;
+}
+
 static int acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
 					  const char *propname, const char *nargs_prop,
 					  unsigned int args_count, unsigned int index,
@@ -960,6 +974,9 @@ static int acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
 			if (!device)
 				return -EINVAL;
 
+			if (nargs_prop)
+				args_count = acpi_fwnode_get_args_count(device, nargs_prop);
+
 			element++;
 
 			ret = acpi_get_ref_args(idx == index ? args : NULL,
@@ -978,6 +995,11 @@ static int acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
 			if (!ref_fwnode)
 				return -EINVAL;
 
+			if (nargs_prop) {
+				device = to_acpi_device_node(ref_fwnode);
+				args_count = acpi_fwnode_get_args_count(device, nargs_prop);
+			}
+
 			element++;
 
 			ret = acpi_get_ref_args(idx == index ? args : NULL,
diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..172dfb950328 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