Re: [PATCH v7 10/22] ACPI: platform_profile: Create class for ACPI platform profile

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 19 Nov 2024, Mario Limonciello wrote:

> When registering a platform profile handler create a class device
> that will allow changing a single platform profile handler.
> 
> The class and sysfs group are no longer needed when the platform profile
> core is a module and unloaded, so remove them at that time as well.
> 
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
> Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v7:
>  * Whitespace
>  * Add tag
>  * Drop class_is_registered() check
>  * Remove legacy sysfs before class
> v6:
>  * Catch failures in ida_alloc
>  * Use 4th argument of device_create instead of dev_set_drvdata()
>  * Squash unregister patch
>  * Add module init callback
>  * Move class creation to module init
>  * Update visibility based on group presence
>  * Add back parent device
> v5:
>  * Use ida instead of idr
>  * Use device_unregister instead of device_destroy()
>  * MKDEV (0, 0)
> ---
>  drivers/acpi/platform_profile.c  | 86 ++++++++++++++++++++++++++++++--
>  include/linux/platform_profile.h |  2 +
>  2 files changed, 83 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> index 32affb75e782d..3524a2b4618ed 100644
> --- a/drivers/acpi/platform_profile.c
> +++ b/drivers/acpi/platform_profile.c
> @@ -5,6 +5,7 @@
>  #include <linux/acpi.h>
>  #include <linux/bits.h>
>  #include <linux/init.h>
> +#include <linux/kdev_t.h>
>  #include <linux/mutex.h>
>  #include <linux/platform_profile.h>
>  #include <linux/sysfs.h>
> @@ -22,6 +23,12 @@ static const char * const profile_names[] = {
>  };
>  static_assert(ARRAY_SIZE(profile_names) == PLATFORM_PROFILE_LAST);
>  
> +static DEFINE_IDA(platform_profile_ida);
> +
> +static const struct class platform_profile_class = {
> +	.name = "platform-profile",
> +};
> +
>  static ssize_t platform_profile_choices_show(struct device *dev,
>  					struct device_attribute *attr,
>  					char *buf)
> @@ -105,8 +112,25 @@ static struct attribute *platform_profile_attrs[] = {
>  	NULL
>  };
>  
> +static int profile_class_registered(struct device *dev, const void *data)
> +{
> +	return 1;
> +}
> +
> +static umode_t profile_class_is_visible(struct kobject *kobj, struct attribute *attr, int idx)
> +{
> +	if (!class_find_device(&platform_profile_class, NULL, NULL, profile_class_registered))
> +		return 0;
> +	if (attr == &dev_attr_platform_profile_choices.attr)
> +		return 0444;
> +	if (attr == &dev_attr_platform_profile.attr)
> +		return 0644;

These two should just return attr->mode I think.

> +	return 0;

Is this even necessary for something?

-- 
 i.

> +}
> +
>  static const struct attribute_group platform_profile_group = {
> -	.attrs = platform_profile_attrs
> +	.attrs = platform_profile_attrs,
> +	.is_visible = profile_class_is_visible,
>  };
>  
>  void platform_profile_notify(struct platform_profile_handler *pprof)
> @@ -164,25 +188,77 @@ int platform_profile_register(struct platform_profile_handler *pprof)
>  	if (cur_profile)
>  		return -EEXIST;
>  
> -	err = sysfs_create_group(acpi_kobj, &platform_profile_group);
> -	if (err)
> -		return err;
> +	/* create class interface for individual handler */
> +	pprof->minor = ida_alloc(&platform_profile_ida, GFP_KERNEL);
> +	if (pprof->minor < 0)
> +		return pprof->minor;
> +	pprof->class_dev = device_create(&platform_profile_class, pprof->dev,
> +					 MKDEV(0, 0), pprof, "platform-profile-%d",
> +					 pprof->minor);
> +	if (IS_ERR(pprof->class_dev)) {
> +		err = PTR_ERR(pprof->class_dev);
> +		goto cleanup_ida;
> +	}
>  
>  	cur_profile = pprof;
> +
> +	err = sysfs_update_group(acpi_kobj, &platform_profile_group);
> +	if (err)
> +		goto cleanup_cur;
> +
>  	return 0;
> +
> +cleanup_cur:
> +	cur_profile = NULL;
> +	device_unregister(pprof->class_dev);
> +
> +cleanup_ida:
> +	ida_free(&platform_profile_ida, pprof->minor);
> +
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(platform_profile_register);
>  
>  int platform_profile_remove(struct platform_profile_handler *pprof)
>  {
> +	int id;
>  	guard(mutex)(&profile_lock);
>  
> -	sysfs_remove_group(acpi_kobj, &platform_profile_group);
>  	cur_profile = NULL;
> +
> +	id = pprof->minor;
> +	device_unregister(pprof->class_dev);
> +	ida_free(&platform_profile_ida, id);
> +
> +	sysfs_update_group(acpi_kobj, &platform_profile_group);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(platform_profile_remove);
>  
> +static int __init platform_profile_init(void)
> +{
> +	int err;
> +
> +	err = class_register(&platform_profile_class);
> +	if (err)
> +		return err;
> +
> +	err = sysfs_create_group(acpi_kobj, &platform_profile_group);
> +	if (err)
> +		class_unregister(&platform_profile_class);
> +
> +	return err;
> +}
> +
> +static void __exit platform_profile_exit(void)
> +{
> +	sysfs_remove_group(acpi_kobj, &platform_profile_group);
> +	class_unregister(&platform_profile_class);
> +}
> +module_init(platform_profile_init);
> +module_exit(platform_profile_exit);
> +
>  MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
>  MODULE_DESCRIPTION("ACPI platform profile sysfs interface");
>  MODULE_LICENSE("GPL");
> diff --git a/include/linux/platform_profile.h b/include/linux/platform_profile.h
> index 8ec0b8da56db5..a888fd085c513 100644
> --- a/include/linux/platform_profile.h
> +++ b/include/linux/platform_profile.h
> @@ -29,6 +29,8 @@ enum platform_profile_option {
>  struct platform_profile_handler {
>  	const char *name;
>  	struct device *dev;
> +	struct device *class_dev;
> +	int minor;
>  	unsigned long choices[BITS_TO_LONGS(PLATFORM_PROFILE_LAST)];
>  	int (*profile_get)(struct platform_profile_handler *pprof,
>  				enum platform_profile_option *profile);
>