[PATCH v1 0/3] Replace acpi_driver with platform_driver

[PATCH v1 0/3] Replace acpi_driver with platform_driver

[Michal Wilczynski]

This patchset is a continuation of efforts from [1] aiming to replace
acpi_driver with platform_driver. To ease up review effort I'm sending
miniseries per driver, with a replacement patch + various improvements
that were noticed by me, or during internal review.

This mini-series takes care of acpi_pad driver.

[1] - https://lore.kernel.org/linux-acpi/20231011083334.3987477-1-michal.wilczynski@intel.com/T/#t

Michal Wilczynski (3):
  ACPI: acpi_pad: Replace acpi_driver with platform_driver
  ACPI: acpi_pad: Use dev groups for sysfs
  ACPI: acpi_pad: Rename ACPI device from device to adev

 drivers/acpi/acpi_pad.c | 93 +++++++++++++++++------------------------
 1 file changed, 38 insertions(+), 55 deletions(-)

-- 
2.41.0

[PATCH v1 1/3] ACPI: acpi_pad: Replace acpi_driver with platform_driver

[Michal Wilczynski]

The acpi_pad driver uses struct acpi_driver to register itself while it
would be more logically consistent to use struct platform_driver for this
purpose, because the corresponding platform device is present and the
role of struct acpi_device is to amend the other bus types. ACPI devices
are not meant to be used as proper representation of hardware entities,
but to collect information on those hardware entities provided by the
platform firmware.

Use struct platform_driver for registering the acpi_pad driver.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
 drivers/acpi/acpi_pad.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index 7a453c5ff303..36e1049833a3 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -18,6 +18,7 @@
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/perf_event.h>
+#include <linux/platform_device.h>
 #include <asm/mwait.h>
 #include <xen/xen.h>
 
@@ -413,16 +414,16 @@ static void acpi_pad_handle_notify(acpi_handle handle)
 	mutex_unlock(&isolated_cpus_lock);
 }
 
-static void acpi_pad_notify(acpi_handle handle, u32 event,
-	void *data)
+static void acpi_pad_notify(acpi_handle handle, u32 event, void *data)
 {
-	struct acpi_device *device = data;
+	struct device *dev = data;
+	struct acpi_device *device = ACPI_COMPANION(dev);
 
 	switch (event) {
 	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 		acpi_pad_handle_notify(handle);
 		acpi_bus_generate_netlink_event(device->pnp.device_class,
-			dev_name(&device->dev), event, 0);
+						dev_name(dev), event, 0);
 		break;
 	default:
 		pr_warn("Unsupported event [0x%x]\n", event);
@@ -430,8 +431,10 @@ static void acpi_pad_notify(acpi_handle handle, u32 event,
 	}
 }
 
-static int acpi_pad_add(struct acpi_device *device)
+static int acpi_pad_probe(struct platform_device *pdev)
 {
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct device *dev = &pdev->dev;
 	acpi_status status;
 
 	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
@@ -441,7 +444,9 @@ static int acpi_pad_add(struct acpi_device *device)
 		return -ENODEV;
 
 	status = acpi_install_notify_handler(device->handle,
-		ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
+					     ACPI_DEVICE_NOTIFY,
+					     acpi_pad_notify,
+					     dev);
 	if (ACPI_FAILURE(status)) {
 		acpi_pad_remove_sysfs(device);
 		return -ENODEV;
@@ -450,14 +455,17 @@ static int acpi_pad_add(struct acpi_device *device)
 	return 0;
 }
 
-static void acpi_pad_remove(struct acpi_device *device)
+static void acpi_pad_remove(struct platform_device *pdev)
 {
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+
 	mutex_lock(&isolated_cpus_lock);
 	acpi_pad_idle_cpus(0);
 	mutex_unlock(&isolated_cpus_lock);
 
 	acpi_remove_notify_handler(device->handle,
-		ACPI_DEVICE_NOTIFY, acpi_pad_notify);
+				   ACPI_DEVICE_NOTIFY,
+				   acpi_pad_notify);
 	acpi_pad_remove_sysfs(device);
 }
 
@@ -467,13 +475,12 @@ static const struct acpi_device_id pad_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 
-static struct acpi_driver acpi_pad_driver = {
-	.name = "processor_aggregator",
-	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
-	.ids = pad_device_ids,
-	.ops = {
-		.add = acpi_pad_add,
-		.remove = acpi_pad_remove,
+static struct platform_driver acpi_pad_driver = {
+	.probe = acpi_pad_probe,
+	.remove_new = acpi_pad_remove,
+	.driver = {
+		.name = "processor_aggregator",
+		.acpi_match_table = pad_device_ids,
 	},
 };
 
@@ -487,12 +494,12 @@ static int __init acpi_pad_init(void)
 	if (power_saving_mwait_eax == 0)
 		return -EINVAL;
 
-	return acpi_bus_register_driver(&acpi_pad_driver);
+	return platform_driver_register(&acpi_pad_driver);
 }
 
 static void __exit acpi_pad_exit(void)
 {
-	acpi_bus_unregister_driver(&acpi_pad_driver);
+	platform_driver_unregister(&acpi_pad_driver);
 }
 
 module_init(acpi_pad_init);
-- 
2.41.0

[PATCH v1 2/3] ACPI: acpi_pad: Use dev groups for sysfs

[Michal Wilczynski]

Change the way sysfs files are created. Use dev_groups, as it's a
better approach - it allows to declare attributes, and the core code
would take care of the lifecycle of those objects.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
 drivers/acpi/acpi_pad.c | 42 +++++++++--------------------------------
 1 file changed, 9 insertions(+), 33 deletions(-)

diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index 36e1049833a3..2513028a0299 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -337,33 +337,14 @@ static ssize_t idlecpus_show(struct device *dev,
 
 static DEVICE_ATTR_RW(idlecpus);
 
-static int acpi_pad_add_sysfs(struct acpi_device *device)
-{
-	int result;
-
-	result = device_create_file(&device->dev, &dev_attr_idlecpus);
-	if (result)
-		return -ENODEV;
-	result = device_create_file(&device->dev, &dev_attr_idlepct);
-	if (result) {
-		device_remove_file(&device->dev, &dev_attr_idlecpus);
-		return -ENODEV;
-	}
-	result = device_create_file(&device->dev, &dev_attr_rrtime);
-	if (result) {
-		device_remove_file(&device->dev, &dev_attr_idlecpus);
-		device_remove_file(&device->dev, &dev_attr_idlepct);
-		return -ENODEV;
-	}
-	return 0;
-}
+static struct attribute *acpi_pad_attrs[] = {
+	&dev_attr_idlecpus.attr,
+	&dev_attr_idlepct.attr,
+	&dev_attr_rrtime.attr,
+	NULL
+};
 
-static void acpi_pad_remove_sysfs(struct acpi_device *device)
-{
-	device_remove_file(&device->dev, &dev_attr_idlecpus);
-	device_remove_file(&device->dev, &dev_attr_idlepct);
-	device_remove_file(&device->dev, &dev_attr_rrtime);
-}
+ATTRIBUTE_GROUPS(acpi_pad);
 
 /*
  * Query firmware how many CPUs should be idle
@@ -440,17 +421,12 @@ static int acpi_pad_probe(struct platform_device *pdev)
 	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 
-	if (acpi_pad_add_sysfs(device))
-		return -ENODEV;
-
 	status = acpi_install_notify_handler(device->handle,
 					     ACPI_DEVICE_NOTIFY,
 					     acpi_pad_notify,
 					     dev);
-	if (ACPI_FAILURE(status)) {
-		acpi_pad_remove_sysfs(device);
+	if (ACPI_FAILURE(status))
 		return -ENODEV;
-	}
 
 	return 0;
 }
@@ -466,7 +442,6 @@ static void acpi_pad_remove(struct platform_device *pdev)
 	acpi_remove_notify_handler(device->handle,
 				   ACPI_DEVICE_NOTIFY,
 				   acpi_pad_notify);
-	acpi_pad_remove_sysfs(device);
 }
 
 static const struct acpi_device_id pad_device_ids[] = {
@@ -479,6 +454,7 @@ static struct platform_driver acpi_pad_driver = {
 	.probe = acpi_pad_probe,
 	.remove_new = acpi_pad_remove,
 	.driver = {
+		.dev_groups = acpi_pad_groups,
 		.name = "processor_aggregator",
 		.acpi_match_table = pad_device_ids,
 	},
-- 
2.41.0

[PATCH v1 3/3] ACPI: acpi_pad: Rename ACPI device from device to adev

[Michal Wilczynski]

Since transformation from ACPI driver to platform driver there are two
devices on which the driver operates - ACPI device and platform device.
For the sake of reader this calls for the distinction in their naming,
to avoid confusion. Rename device to adev, as corresponding
platform device is called pdev.

Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
 drivers/acpi/acpi_pad.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index 2513028a0299..87cf2234ecd2 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -398,12 +398,12 @@ static void acpi_pad_handle_notify(acpi_handle handle)
 static void acpi_pad_notify(acpi_handle handle, u32 event, void *data)
 {
 	struct device *dev = data;
-	struct acpi_device *device = ACPI_COMPANION(dev);
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 
 	switch (event) {
 	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 		acpi_pad_handle_notify(handle);
-		acpi_bus_generate_netlink_event(device->pnp.device_class,
+		acpi_bus_generate_netlink_event(adev->pnp.device_class,
 						dev_name(dev), event, 0);
 		break;
 	default:
@@ -414,14 +414,14 @@ static void acpi_pad_notify(acpi_handle handle, u32 event, void *data)
 
 static int acpi_pad_probe(struct platform_device *pdev)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
 	struct device *dev = &pdev->dev;
 	acpi_status status;
 
-	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
-	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
+	strcpy(acpi_device_name(adev), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
+	strcpy(acpi_device_class(adev), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 
-	status = acpi_install_notify_handler(device->handle,
+	status = acpi_install_notify_handler(adev->handle,
 					     ACPI_DEVICE_NOTIFY,
 					     acpi_pad_notify,
 					     dev);
@@ -433,13 +433,13 @@ static int acpi_pad_probe(struct platform_device *pdev)
 
 static void acpi_pad_remove(struct platform_device *pdev)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
 
 	mutex_lock(&isolated_cpus_lock);
 	acpi_pad_idle_cpus(0);
 	mutex_unlock(&isolated_cpus_lock);
 
-	acpi_remove_notify_handler(device->handle,
+	acpi_remove_notify_handler(adev->handle,
 				   ACPI_DEVICE_NOTIFY,
 				   acpi_pad_notify);
 }
-- 
2.41.0

Re: [PATCH v1 1/3] ACPI: acpi_pad: Replace acpi_driver with platform_driver

[Rafael J. Wysocki]

On Mon, Oct 16, 2023 at 8:42 PM Michal Wilczynski
<michal.wilczynski@intel.com> wrote:
>
> The acpi_pad driver uses struct acpi_driver to register itself while it
> would be more logically consistent to use struct platform_driver for this
> purpose, because the corresponding platform device is present and the
> role of struct acpi_device is to amend the other bus types. ACPI devices
> are not meant to be used as proper representation of hardware entities,
> but to collect information on those hardware entities provided by the
> platform firmware.
>
> Use struct platform_driver for registering the acpi_pad driver.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
> ---
>  drivers/acpi/acpi_pad.c | 41 ++++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
> index 7a453c5ff303..36e1049833a3 100644
> --- a/drivers/acpi/acpi_pad.c
> +++ b/drivers/acpi/acpi_pad.c
> @@ -18,6 +18,7 @@
>  #include <linux/slab.h>
>  #include <linux/acpi.h>
>  #include <linux/perf_event.h>
> +#include <linux/platform_device.h>
>  #include <asm/mwait.h>
>  #include <xen/xen.h>
>
> @@ -413,16 +414,16 @@ static void acpi_pad_handle_notify(acpi_handle handle)
>         mutex_unlock(&isolated_cpus_lock);
>  }
>
> -static void acpi_pad_notify(acpi_handle handle, u32 event,
> -       void *data)
> +static void acpi_pad_notify(acpi_handle handle, u32 event, void *data)
>  {
> -       struct acpi_device *device = data;
> +       struct device *dev = data;
> +       struct acpi_device *device = ACPI_COMPANION(dev);
>
>         switch (event) {
>         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
>                 acpi_pad_handle_notify(handle);
>                 acpi_bus_generate_netlink_event(device->pnp.device_class,
> -                       dev_name(&device->dev), event, 0);
> +                                               dev_name(dev), event, 0);

This is the same mistake as in the analogous AC driver patch, as it
changes the binary interface between the kernel and user space.

Please leave it as is for now (at least in this patch).

>                 break;
>         default:
>                 pr_warn("Unsupported event [0x%x]\n", event);
> @@ -430,8 +431,10 @@ static void acpi_pad_notify(acpi_handle handle, u32 event,
>         }
>  }
>
> -static int acpi_pad_add(struct acpi_device *device)
> +static int acpi_pad_probe(struct platform_device *pdev)
>  {
> +       struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
> +       struct device *dev = &pdev->dev;
>         acpi_status status;
>
>         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
> @@ -441,7 +444,9 @@ static int acpi_pad_add(struct acpi_device *device)
>                 return -ENODEV;
>
>         status = acpi_install_notify_handler(device->handle,
> -               ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
> +                                            ACPI_DEVICE_NOTIFY,
> +                                            acpi_pad_notify,
> +                                            dev);

Passing the struct acpi_device pointer as the last argument here is
fine, no need to change that.

>         if (ACPI_FAILURE(status)) {
>                 acpi_pad_remove_sysfs(device);
>                 return -ENODEV;
> @@ -450,14 +455,17 @@ static int acpi_pad_add(struct acpi_device *device)
>         return 0;
>  }
>
> -static void acpi_pad_remove(struct acpi_device *device)
> +static void acpi_pad_remove(struct platform_device *pdev)
>  {
> +       struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
> +
>         mutex_lock(&isolated_cpus_lock);
>         acpi_pad_idle_cpus(0);
>         mutex_unlock(&isolated_cpus_lock);
>
>         acpi_remove_notify_handler(device->handle,
> -               ACPI_DEVICE_NOTIFY, acpi_pad_notify);
> +                                  ACPI_DEVICE_NOTIFY,
> +                                  acpi_pad_notify);

The white space cleanup can be done in a separate patch (here and in
the other places).

>         acpi_pad_remove_sysfs(device);
>  }
>
> @@ -467,13 +475,12 @@ static const struct acpi_device_id pad_device_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(acpi, pad_device_ids);
>
> -static struct acpi_driver acpi_pad_driver = {
> -       .name = "processor_aggregator",
> -       .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
> -       .ids = pad_device_ids,
> -       .ops = {
> -               .add = acpi_pad_add,
> -               .remove = acpi_pad_remove,
> +static struct platform_driver acpi_pad_driver = {
> +       .probe = acpi_pad_probe,
> +       .remove_new = acpi_pad_remove,
> +       .driver = {
> +               .name = "processor_aggregator",
> +               .acpi_match_table = pad_device_ids,
>         },
>  };
>
> @@ -487,12 +494,12 @@ static int __init acpi_pad_init(void)
>         if (power_saving_mwait_eax == 0)
>                 return -EINVAL;
>
> -       return acpi_bus_register_driver(&acpi_pad_driver);
> +       return platform_driver_register(&acpi_pad_driver);
>  }
>
>  static void __exit acpi_pad_exit(void)
>  {
> -       acpi_bus_unregister_driver(&acpi_pad_driver);
> +       platform_driver_unregister(&acpi_pad_driver);
>  }
>
>  module_init(acpi_pad_init);
> --