[PATCH v2 0/3] platform/x86: system76: Bind to a platform device instead of an ACPI one

[PATCH v2 0/3] platform/x86: system76: Bind to a platform device instead of an ACPI one

[Rafael J. Wysocki]

Hi All,

This is an update of

https://lore.kernel.org/linux-acpi/2841136.mvXUDI8C0e@rafael.j.wysocki/

adding one preparatory patch and updating the other patches to implement
the probe rollback code path slightly differently.

The original description of the patch series below is still mostly
applicable.

This series is part of a larger effort to switch over all drivers using
the struct acpi_driver interface to the more common struct platform_driver
interface and eliminate the former.  The background is explained in
Documentation/driver-api/acpi/acpi-drivers.rst and in the changelog of
the patch that introduced the above document:

https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/

The bottom line is that the kernel would be better off without struct
acpi_driver and so it is better to get rid of it.

This series carries out driver conversion of the platform x86 System76
ACPI driver.

Patch [1/3] removes redundant devm_led_classdev_unregister() calls from
system76_remove().

Patch [2/3] updates the driver to install an ACPI notify handler by itself
instead of using the .notify() callback from struct acpi_driver, which is
requisite for the driver conversion.

Patch [3/3] converts the driver to using struct platform_driver for device
binding.

Thanks!

[PATCH v2 1/3] platform/x86: system76: Drop redundant devm_led_classdev_unregister()

[Rafael J. Wysocki]

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

Drop two redundant devm_led_classdev_unregister() calls from
system76_remove().

No intentional functional impact.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: New patch

---
 drivers/platform/x86/system76_acpi.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/platform/x86/system76_acpi.c b/drivers/platform/x86/system76_acpi.c
index 3da753b3d00d..d8b64e2c2713 100644
--- a/drivers/platform/x86/system76_acpi.c
+++ b/drivers/platform/x86/system76_acpi.c
@@ -800,9 +800,6 @@ static void system76_remove(struct acpi_device *acpi_dev)
 		kfree(data->ntmp);
 	}
 
-	devm_led_classdev_unregister(&acpi_dev->dev, &data->ap_led);
-	devm_led_classdev_unregister(&acpi_dev->dev, &data->kb_led);
-
 	system76_get(data, "FINI");
 }
 
-- 
2.51.0

[PATCH v2 2/3] platform/x86: system76: Register ACPI notify handler directly

[Rafael J. Wysocki]

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

To facilitate subsequent conversion of the driver to a platform one,
make it install an ACPI notify handler directly instead of using
a .notify() callback in struct acpi_driver.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2:
   * Rebase on top of [1/3]
   * Use the observation that the notify handler does not access memory
     allocated when data->has_open_ec is set and so it can be registered
     earlier, which allows the probe rollback path to be simplified

---
 drivers/platform/x86/system76_acpi.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/system76_acpi.c b/drivers/platform/x86/system76_acpi.c
index d8b64e2c2713..fc11427c36a5 100644
--- a/drivers/platform/x86/system76_acpi.c
+++ b/drivers/platform/x86/system76_acpi.c
@@ -644,11 +644,10 @@ static void input_key(struct system76_data *data, unsigned int code)
 }
 
 // Handle ACPI notification
-static void system76_notify(struct acpi_device *acpi_dev, u32 event)
+static void system76_notify(acpi_handle handle, u32 event, void *context)
 {
-	struct system76_data *data;
+	struct system76_data *data = context;
 
-	data = acpi_driver_data(acpi_dev);
 	switch (event) {
 	case 0x80:
 		kb_led_hotkey_hardware(data);
@@ -757,7 +756,12 @@ static int system76_add(struct acpi_device *acpi_dev)
 
 	err = input_register_device(data->input);
 	if (err)
-		goto error;
+		return err;
+
+	err = acpi_dev_install_notify_handler(acpi_dev, ACPI_DEVICE_NOTIFY,
+					      system76_notify, data);
+	if (err)
+		return err;
 
 	if (data->has_open_ec) {
 		err = system76_get_object(data, "NFAN", &data->nfan);
@@ -784,6 +788,7 @@ static int system76_add(struct acpi_device *acpi_dev)
 		kfree(data->ntmp);
 		kfree(data->nfan);
 	}
+	acpi_dev_remove_notify_handler(acpi_dev, ACPI_DEVICE_NOTIFY, system76_notify);
 	return err;
 }
 
@@ -800,6 +805,8 @@ static void system76_remove(struct acpi_device *acpi_dev)
 		kfree(data->ntmp);
 	}
 
+	acpi_dev_remove_notify_handler(acpi_dev, ACPI_DEVICE_NOTIFY, system76_notify);
+
 	system76_get(data, "FINI");
 }
 
@@ -810,7 +817,6 @@ static struct acpi_driver system76_driver = {
 	.ops = {
 		.add = system76_add,
 		.remove = system76_remove,
-		.notify = system76_notify,
 	},
 };
 module_acpi_driver(system76_driver);
-- 
2.51.0

[PATCH v2 3/3] platform/x86: system76: Convert ACPI driver to a platform one

[Rafael J. Wysocki]

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

In all cases in which a struct acpi_driver is used for binding a driver
to an ACPI device object, a corresponding platform device is created by
the ACPI core and that device is regarded as a proper representation of
underlying hardware.  Accordingly, a struct platform_driver should be
used by driver code to bind to that device.  There are multiple reasons
why drivers should not bind directly to ACPI device objects [1].

Overall, it is better to bind drivers to platform devices than to their
ACPI companions, so convert the System76 ACPI driver to a platform one.

After this change, the subordinate hwmon, input and LED class devices
will be registered under the platform device used for driver binding
instead of its ACPI companion.

While this is not expected to alter functionality, it changes sysfs
layout and so it will be visible to user space.

Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: Rebase on top of the new [1/3] and the updated [2/3].

---
 drivers/platform/x86/system76_acpi.c | 48 +++++++++++++++-------------
 1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/drivers/platform/x86/system76_acpi.c b/drivers/platform/x86/system76_acpi.c
index fc11427c36a5..693cbb461382 100644
--- a/drivers/platform/x86/system76_acpi.c
+++ b/drivers/platform/x86/system76_acpi.c
@@ -18,6 +18,7 @@
 #include <linux/leds.h>
 #include <linux/module.h>
 #include <linux/pci_ids.h>
+#include <linux/platform_device.h>
 #include <linux/power_supply.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
@@ -670,16 +671,19 @@ static void system76_notify(acpi_handle handle, u32 event, void *context)
 	}
 }
 
-// Add a System76 ACPI device
-static int system76_add(struct acpi_device *acpi_dev)
+// Probe a System76 platform device
+static int system76_probe(struct platform_device *pdev)
 {
+	struct acpi_device *acpi_dev = ACPI_COMPANION(&pdev->dev);
 	struct system76_data *data;
 	int err;
 
-	data = devm_kzalloc(&acpi_dev->dev, sizeof(*data), GFP_KERNEL);
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
-	acpi_dev->driver_data = data;
+
+	platform_set_drvdata(pdev, data);
+
 	data->acpi_dev = acpi_dev;
 
 	// Some models do not run open EC firmware. Check for an ACPI method
@@ -695,7 +699,7 @@ static int system76_add(struct acpi_device *acpi_dev)
 	data->ap_led.brightness_set_blocking = ap_led_set;
 	data->ap_led.max_brightness = 1;
 	data->ap_led.default_trigger = "rfkill-none";
-	err = devm_led_classdev_register(&acpi_dev->dev, &data->ap_led);
+	err = devm_led_classdev_register(&pdev->dev, &data->ap_led);
 	if (err)
 		return err;
 
@@ -739,19 +743,19 @@ static int system76_add(struct acpi_device *acpi_dev)
 	}
 
 	if (data->kbled_type != KBLED_NONE) {
-		err = devm_led_classdev_register(&acpi_dev->dev, &data->kb_led);
+		err = devm_led_classdev_register(&pdev->dev, &data->kb_led);
 		if (err)
 			return err;
 	}
 
-	data->input = devm_input_allocate_device(&acpi_dev->dev);
+	data->input = devm_input_allocate_device(&pdev->dev);
 	if (!data->input)
 		return -ENOMEM;
 
 	data->input->name = "System76 ACPI Hotkeys";
 	data->input->phys = "system76_acpi/input0";
 	data->input->id.bustype = BUS_HOST;
-	data->input->dev.parent = &acpi_dev->dev;
+	data->input->dev.parent = &pdev->dev;
 	input_set_capability(data->input, EV_KEY, KEY_SCREENLOCK);
 
 	err = input_register_device(data->input);
@@ -772,7 +776,7 @@ static int system76_add(struct acpi_device *acpi_dev)
 		if (err)
 			goto error;
 
-		data->therm = devm_hwmon_device_register_with_info(&acpi_dev->dev,
+		data->therm = devm_hwmon_device_register_with_info(&pdev->dev,
 			"system76_acpi", data, &thermal_chip_info, NULL);
 		err = PTR_ERR_OR_ZERO(data->therm);
 		if (err)
@@ -792,12 +796,10 @@ static int system76_add(struct acpi_device *acpi_dev)
 	return err;
 }
 
-// Remove a System76 ACPI device
-static void system76_remove(struct acpi_device *acpi_dev)
+// Remove a System76 platform device
+static void system76_remove(struct platform_device *pdev)
 {
-	struct system76_data *data;
-
-	data = acpi_driver_data(acpi_dev);
+	struct system76_data *data = platform_get_drvdata(pdev);
 
 	if (data->has_open_ec) {
 		system76_battery_exit();
@@ -805,21 +807,21 @@ static void system76_remove(struct acpi_device *acpi_dev)
 		kfree(data->ntmp);
 	}
 
-	acpi_dev_remove_notify_handler(acpi_dev, ACPI_DEVICE_NOTIFY, system76_notify);
+	acpi_dev_remove_notify_handler(ACPI_COMPANION(&pdev->dev),
+				       ACPI_DEVICE_NOTIFY, system76_notify);
 
 	system76_get(data, "FINI");
 }
 
-static struct acpi_driver system76_driver = {
-	.name = "System76 ACPI Driver",
-	.class = "hotkey",
-	.ids = device_ids,
-	.ops = {
-		.add = system76_add,
-		.remove = system76_remove,
+static struct platform_driver system76_driver = {
+	.probe = system76_probe,
+	.remove = system76_remove,
+	.driver = {
+		.name = "System76 ACPI Driver",
+		.acpi_match_table = device_ids,
 	},
 };
-module_acpi_driver(system76_driver);
+module_platform_driver(system76_driver);
 
 MODULE_DESCRIPTION("System76 ACPI Driver");
 MODULE_AUTHOR("Jeremy Soller <jeremy@system76.com>");
-- 
2.51.0

Re: [PATCH v2 0/3] platform/x86: system76: Bind to a platform device instead of an ACPI one

[Ilpo Järvinen]

On Wed, 18 Mar 2026 14:48:57 +0100, Rafael J. Wysocki wrote:

> This is an update of
> 
> https://lore.kernel.org/linux-acpi/2841136.mvXUDI8C0e@rafael.j.wysocki/
> 
> adding one preparatory patch and updating the other patches to implement
> the probe rollback code path slightly differently.
> 
> [...]


Thank you for your contribution, it has been applied to my local
review-ilpo-next branch. Note it will show up in the public
platform-drivers-x86/review-ilpo-next branch only once I've pushed my
local branch there, which might take a while.

The list of commits applied:
[1/3] platform/x86: system76: Drop redundant devm_led_classdev_unregister()
      commit: 5539165cae8e133275f0eed4cfa131cda974a1a3
[2/3] platform/x86: system76: Register ACPI notify handler directly
      commit: 89729c9c6c158259b8de14c57b5aac6a25dfac3d
[3/3] platform/x86: system76: Convert ACPI driver to a platform one
      commit: 80b8f68b94abcf6f2f8c71a685b2a70fd7c502b0

--
 i.