linux-kernel - [PATCH v1 01/10] ACPI: scan: Register platform devices for fixed event buttons

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Message-ID: <3322931.5fSG56mABF@rafael.j.wysocki>
Date: Tue, 09 Dec 2025 14:53:02 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux ACPI <linux-acpi@...r.kernel.org>
Cc: Hans de Goede <hdegoede@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
 Linux PM <linux-pm@...r.kernel.org>,
 Thomas Weißschuh <linux@...ssschuh.net>,
 Armin Wolf <w_armin@....de>
Subject:
 [PATCH v1 01/10] ACPI: scan: Register platform devices for fixed event
 buttons

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

On platforms using ACPI, power and sleep buttons may be so called "fixed
event devices" in which case they are hooked up directly to the Fixed
Events register in the platform via dedicated lines and there are no
corresponding device objects in the ACPI namespace.  Nevertheless, in
Linux they get corresponding struct acpi_device objects with special
device IDs, either LNXPWRBN or LNXSLPBN, which are then used for driver
binding in a ususal way.

However, the function creating those struct acpi_device objects for
"fixed event device" buttons, acpi_bus_scan_fixed(), does not register
platform devices for them, unlike the generic code handling device
enumeration based on the ACPI namespace.  Consequently, if an ACPI power
or sleep button is represented by a device object in the ACPI namespace,
it will get a corresponding platform device, but if it is a "fixed event
device", it will not get one, which is inconsistent and prevents the
ACPI power button driver from being converted into a platform driver.

For the sake of consistency and to allow the ACPI power button driver to
become a platform one going forward, modify acpi_bus_scan_fixed() to
register platform devices for "fixed event device" buttons and update
ACPI platform device registration code to work with non-device ACPI
object types, so it can handle the buttons in question.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/acpi_platform.c |   29 ++++++++++++++++-------------
 drivers/acpi/scan.c          |    4 ++++
 2 files changed, 20 insertions(+), 13 deletions(-)

--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -138,21 +138,24 @@ struct platform_device *acpi_create_plat
 	}

 	INIT_LIST_HEAD(&resource_list);
-	count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
-	if (count < 0)
-		return NULL;
-	if (count > 0) {
-		resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
-		if (!resources) {
+	if (adev->device_type == ACPI_BUS_TYPE_DEVICE) {
+		count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
+		if (count < 0)
+			return NULL;
+
+		if (count > 0) {
+			resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
+			if (!resources) {
+				acpi_dev_free_resource_list(&resource_list);
+				return ERR_PTR(-ENOMEM);
+			}
+			count = 0;
+			list_for_each_entry(rentry, &resource_list, node)
+				acpi_platform_fill_resource(adev, rentry->res,
+							    &resources[count++]);
+
 			acpi_dev_free_resource_list(&resource_list);
-			return ERR_PTR(-ENOMEM);
 		}
-		count = 0;
-		list_for_each_entry(rentry, &resource_list, node)
-			acpi_platform_fill_resource(adev, rentry->res,
-						    &resources[count++]);
-
-		acpi_dev_free_resource_list(&resource_list);
 	}

 	memset(&pdevinfo, 0, sizeof(pdevinfo));
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2660,6 +2660,8 @@ static void acpi_bus_scan_fixed(void)
 				device_init_wakeup(&adev->dev, true);
 			else
 				dev_dbg(&adev->dev, "No driver\n");
+
+			acpi_default_enumeration(adev);
 		}
 	}

@@ -2672,6 +2674,8 @@ static void acpi_bus_scan_fixed(void)
 			adev->flags.match_driver = true;
 			if (device_attach(&adev->dev) < 0)
 				dev_dbg(&adev->dev, "No driver\n");
+
+			acpi_default_enumeration(adev);
 		}
 	}
 }