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

[Armin Wolf <W_Armin@gmx.de>]

Am 07.11.24 um 22:09 schrieb Mario Limonciello:

> 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().
>
I meant that requiring "dev" to be set is not necessary. Having a "dev" field inside struct platform_profile_handler is fine.

Thanks,
Armin Wolf

>> 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);
>