Re: [PATCH v5 08/20] ACPI: platform_profile: Create class for ACPI platform profile

[Mario Limonciello <mario.limonciello@amd.com>]

On 11/7/2024 02:16, Armin Wolf wrote:
> Am 07.11.24 um 07:02 schrieb Mario Limonciello:
> 
>> When registering a platform profile handler create a class device
>> that will allow changing a single platform profile handler.
>>
>> Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> v5:
>>   * Use ida instead of idr
>>   * Use device_unregister instead of device_destroy()
>>   * MKDEV (0, 0)
>> ---
>>   drivers/acpi/platform_profile.c  | 50 +++++++++++++++++++++++++++++---
>>   include/linux/platform_profile.h |  2 ++
>>   2 files changed, 48 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/ 
>> platform_profile.c
>> index 0450bdae7c88b..652034b71ee9b 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)
>> @@ -113,6 +120,8 @@ void platform_profile_notify(void)
>>   {
>>       if (!cur_profile)
>>           return;
>> +    if (!class_is_registered(&platform_profile_class))
>> +        return;
>>       sysfs_notify(acpi_kobj, NULL, "platform_profile");
>>   }
>>   EXPORT_SYMBOL_GPL(platform_profile_notify);
>> @@ -123,6 +132,9 @@ int platform_profile_cycle(void)
>>       enum platform_profile_option next;
>>       int err;
>>
>> +    if (!class_is_registered(&platform_profile_class))
>> +        return -ENODEV;
>> +
>>       scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) {
>>           if (!cur_profile)
>>               return -ENODEV;
>> @@ -163,20 +175,50 @@ 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;
>> +    if (!class_is_registered(&platform_profile_class)) {
>> +        /* class for individual handlers */
>> +        err = class_register(&platform_profile_class);
>> +        if (err)
>> +            return err;
>> +        /* legacy sysfs files */
>> +        err = sysfs_create_group(acpi_kobj, &platform_profile_group);
>> +        if (err)
>> +            goto cleanup_class;
>> +    }
>> +
>> +    /* create class interface for individual handler */
>> +    pprof->minor = ida_alloc(&platform_profile_ida, GFP_KERNEL);
> 
> Missing error handling.

Ack.

> 
>> +    pprof->class_dev = device_create(&platform_profile_class, NULL,
>> +                     MKDEV(0, 0), NULL, "platform-profile-%d",
>> +                     pprof->minor);
> 
> Two things:
> 
> 1. Please allow drivers to pass in their struct device so the resulting 
> class device
> has a parent device. This would allow userspace applications to 
> determine which device
> handles which platform profile device. This parameter is optional and 
> can be NULL.
> 

I previously did this indirectly by letting them set it in the
"struct platform_profile_handler *pprof" and then used that value.

You had said that wasn't necessary so I dropped that patch.  I would 
rather go back to including that then having another argument to 
platform_profile_register().

> 2. Please use the fourth argument of device_create() instead of 
> dev_set_drvdata().

OK.

> 
> Thanks,
> Armin Wolf
> 
>> +    if (IS_ERR(pprof->class_dev)) {
>> +        err = PTR_ERR(pprof->class_dev);
>> +        goto cleanup_ida;
>> +    }
>> +    dev_set_drvdata(pprof->class_dev, pprof);
>>
>>       cur_profile = pprof;
>>       return 0;
>> +
>> +cleanup_ida:
>> +    ida_free(&platform_profile_ida, pprof->minor);
>> +
>> +cleanup_class:
>> +    class_unregister(&platform_profile_class);
>> +
>> +    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);
>> +    id = pprof->minor;
>> +    device_unregister(pprof->class_dev);
>> +    ida_free(&platform_profile_ida, id);
>> +
>>       cur_profile = NULL;
>>       return 0;
>>   }
>> diff --git a/include/linux/platform_profile.h b/include/linux/ 
>> platform_profile.h
>> index 58279b76d740e..d92a035e6ba6a 100644
>> --- a/include/linux/platform_profile.h
>> +++ b/include/linux/platform_profile.h
>> @@ -28,6 +28,8 @@ enum platform_profile_option {
>>
>>   struct platform_profile_handler {
>>       const char *name;
>> +    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);