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

[Mario Limonciello <mario.limonciello@xxxxxxx>]

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@xxxxxxxxx>
> > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > ---
> > 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);