[PATCH v16 05/14] power: reset: reboot-mode: Expose sysfs for registered reboot_modes

[Bartosz Golaszewski]

On Wed, 15 Oct 2025 at 06:39, Shivendra Pratap
<shivendra.pratap at oss.qualcomm.com> wrote:
>
> Currently, there is no standardized mechanism for userspace to
> discover which reboot-modes are supported on a given platform.
> This limitation forces tools and scripts to rely on hardcoded
> assumptions about the supported reboot-modes.
>
> Create a class 'reboot-mode' and a device under it to expose a
> sysfs interface to show the available reboot mode arguments to
> userspace. Use the driver_name field of the struct
> reboot_mode_driver to create the device. For device-based
> drivers, configure the device driver name as driver_name.
>
> This results in the creation of:
>   /sys/class/reboot-mode/<driver>/reboot_modes
>
> This read-only sysfs file will exposes the list of supported
> reboot modes arguments provided by the driver, enabling userspace
> to query the list of arguments.
>
> Align the clean up path to maintain backward compatibility for
> existing reboot-mode based drivers.
>
> Signed-off-by: Shivendra Pratap <shivendra.pratap at oss.qualcomm.com>

[snip]

> +
> +static int create_reboot_mode_device(struct reboot_mode_driver *reboot)
> +{
> +       struct reboot_mode_driver **dr;
> +       int ret = 0;
> +
> +       if (!rb_class) {
> +               rb_class = class_create("reboot-mode");
> +               if (IS_ERR(rb_class))
> +                       return PTR_ERR(rb_class);
> +       }
> +
> +       reboot->reboot_dev = device_create(rb_class, NULL, 0, NULL, reboot->driver_name);
> +       if (IS_ERR(reboot->reboot_dev))
> +               return PTR_ERR(reboot->reboot_dev);
> +
> +       ret = device_create_file(reboot->reboot_dev, &dev_attr_reboot_modes);
> +       if (ret)
> +               goto create_file_err;
> +
> +       dr = devres_alloc(release_reboot_mode_device, sizeof(*dr), GFP_KERNEL);
> +       if (!dr) {
> +               ret = -ENOMEM;
> +               goto devres_alloc_error;
> +       }
> +
> +       *dr = reboot;
> +       devres_add(reboot->reboot_dev, dr);

If you're using devres here - at least make it obvious by adding the
devm_ prefix to the function name and make it take an explicit struct
device * parameter so that it's clear who owns the managed resource.

Bart