linux-kernel - Re: [RFT][PATCH v1 6/6] ACPI: NFIT: core: Convert the driver to a platform one

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Message-ID: <aTsQKAJF5hpOixIR@aschofie-mobl2.lan>
Date: Thu, 11 Dec 2025 10:40:40 -0800
From: Alison Schofield <alison.schofield@...el.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: Linux ACPI <linux-acpi@...r.kernel.org>, LKML
	<linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>, "Armin
 Wolf" <w_armin@....de>, Hans de Goede <hansg@...nel.org>, Dan Williams
	<dan.j.williams@...el.com>, Vishal Verma <vishal.l.verma@...el.com>, "Dave
 Jiang" <dave.jiang@...el.com>, Ira Weiny <ira.weiny@...el.com>,
	<nvdimm@...ts.linux.dev>
Subject: Re: [RFT][PATCH v1 6/6] ACPI: NFIT: core: Convert the driver to a
 platform one

On Thu, Dec 11, 2025 at 03:22:00PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> While binding drivers directly to struct acpi_device objects allows
> basic functionality to be provided, at least in the majority of cases,
> there are some problems with it, related to general consistency, sysfs
> layout, power management operation ordering, and code cleanliness.
> 
> Overall, it is better to bind drivers to platform devices than to their
> ACPI companions, so convert the ACPI NFIT core driver to a platform one.
> 
> While this is not expected to alter functionality, it changes sysfs
> layout and so it will be visible to user space.

Changes sysfs layout? That means it changes sysfs paths?
Does it change paths defined in Documentation/ABI/testing/sysfs "What:"


> 
> This change was mostly developed by Michal Wilczynski [1].
> 
> Linu: https://lore.kernel.org/linux-acpi/20231011083334.3987477-6-michal.wilczynski@intel.com/ [1]
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/nfit/core.c |   34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
> 
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2,6 +2,7 @@
>  /*
>   * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
>   */
> +#include <linux/platform_device.h>
>  #include <linux/list_sort.h>
>  #include <linux/libnvdimm.h>
>  #include <linux/module.h>
> @@ -98,7 +99,7 @@ static struct acpi_device *to_acpi_dev(s
>  			|| strcmp(nd_desc->provider_name, "ACPI.NFIT") != 0)
>  		return NULL;
>  
> -	return to_acpi_device(acpi_desc->dev);
> +	return ACPI_COMPANION(acpi_desc->dev);
>  }
>  
>  static int xlat_bus_status(void *buf, unsigned int cmd, u32 status)
> @@ -3283,11 +3284,11 @@ static void acpi_nfit_put_table(void *ta
>  
>  static void acpi_nfit_notify(acpi_handle handle, u32 event, void *data)
>  {
> -	struct acpi_device *adev = data;
> +	struct device *dev = data;
>  
> -	device_lock(&adev->dev);
> -	__acpi_nfit_notify(&adev->dev, handle, event);
> -	device_unlock(&adev->dev);
> +	device_lock(dev);
> +	__acpi_nfit_notify(dev, handle, event);
> +	device_unlock(dev);
>  }
>  
>  static void acpi_nfit_remove_notify_handler(void *data)
> @@ -3328,18 +3329,19 @@ void acpi_nfit_shutdown(void *data)
>  }
>  EXPORT_SYMBOL_GPL(acpi_nfit_shutdown);
>  
> -static int acpi_nfit_add(struct acpi_device *adev)
> +static int acpi_nfit_probe(struct platform_device *pdev)
>  {
>  	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
>  	struct acpi_nfit_desc *acpi_desc;
> -	struct device *dev = &adev->dev;
> +	struct device *dev = &pdev->dev;
> +	struct acpi_device *adev = ACPI_COMPANION(dev);
>  	struct acpi_table_header *tbl;
>  	acpi_status status = AE_OK;
>  	acpi_size sz;
>  	int rc = 0;
>  
>  	rc = acpi_dev_install_notify_handler(adev, ACPI_DEVICE_NOTIFY,
> -					     acpi_nfit_notify, adev);
> +					     acpi_nfit_notify, dev);
>  	if (rc)
>  		return rc;
>  
> @@ -3369,7 +3371,7 @@ static int acpi_nfit_add(struct acpi_dev
>  	acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
>  	if (!acpi_desc)
>  		return -ENOMEM;
> -	acpi_nfit_desc_init(acpi_desc, &adev->dev);
> +	acpi_nfit_desc_init(acpi_desc, dev);
>  
>  	/* Save the acpi header for exporting the revision via sysfs */
>  	acpi_desc->acpi_header = *tbl;
> @@ -3474,11 +3476,11 @@ static const struct acpi_device_id acpi_
>  };
>  MODULE_DEVICE_TABLE(acpi, acpi_nfit_ids);
>  
> -static struct acpi_driver acpi_nfit_driver = {
> -	.name = KBUILD_MODNAME,
> -	.ids = acpi_nfit_ids,
> -	.ops = {
> -		.add = acpi_nfit_add,
> +static struct platform_driver acpi_nfit_driver = {
> +	.probe = acpi_nfit_probe,
> +	.driver = {
> +		.name = "acpi-nfit",
> +		.acpi_match_table = acpi_nfit_ids,
>  	},
>  };
>  
> @@ -3516,7 +3518,7 @@ static __init int nfit_init(void)
>  		return -ENOMEM;
>  
>  	nfit_mce_register();
> -	ret = acpi_bus_register_driver(&acpi_nfit_driver);
> +	ret = platform_driver_register(&acpi_nfit_driver);
>  	if (ret) {
>  		nfit_mce_unregister();
>  		destroy_workqueue(nfit_wq);
> @@ -3529,7 +3531,7 @@ static __init int nfit_init(void)
>  static __exit void nfit_exit(void)
>  {
>  	nfit_mce_unregister();
> -	acpi_bus_unregister_driver(&acpi_nfit_driver);
> +	platform_driver_unregister(&acpi_nfit_driver);
>  	destroy_workqueue(nfit_wq);
>  	WARN_ON(!list_empty(&acpi_descs));
>  }
> 
> 
> 
>