Re: [PATCH v16 02/14] power: reset: reboot-mode: Add device tree node-based registration

[Bartosz Golaszewski <bartosz.golaszewski@linaro.org>]

On Wed, 15 Oct 2025 at 06:38, Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> wrote:
>
> The reboot-mode driver does not have a strict requirement for
> device-based registration. It primarily uses the device's of_node
> to read mode-<cmd> properties and the device pointer for logging.
>
> Remove the dependency on struct device and introduce support for
> firmware node (fwnode) based registration. This enables drivers
> that are not associated with a struct device to leverage the
> reboot-mode framework.
>
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> ---
>  drivers/power/reset/reboot-mode.c | 45 +++++++++++++++++++++++++++++----------
>  include/linux/reboot-mode.h       |  3 ++-
>  2 files changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
> index 8fc3e14638ea757c8dc3808c240ff569cbd74786..c8f71e6f661ae14eb72bdcb1f412cd05faee3dd9 100644
> --- a/drivers/power/reset/reboot-mode.c
> +++ b/drivers/power/reset/reboot-mode.c
> @@ -3,13 +3,17 @@
>   * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
>   */
>
> +#define pr_fmt(fmt)    "reboot-mode: " fmt
> +
>  #include <linux/device.h>
>  #include <linux/init.h>
>  #include <linux/kernel.h>
> +#include <linux/list.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/reboot.h>
>  #include <linux/reboot-mode.h>
> +#include <linux/slab.h>
>
>  #define PREFIX "mode-"
>
> @@ -69,17 +73,26 @@ static int reboot_mode_notify(struct notifier_block *this,
>  /**
>   * reboot_mode_register - register a reboot mode driver
>   * @reboot: reboot mode driver
> + * @fwnode: Firmware node with reboot-mode configuration
>   *
>   * Returns: 0 on success or a negative error code on failure.
>   */
> -int reboot_mode_register(struct reboot_mode_driver *reboot)
> +int reboot_mode_register(struct reboot_mode_driver *reboot, struct fwnode_handle *fwnode)
>  {
>         struct mode_info *info;
> +       struct mode_info *next;
> +       struct device_node *np;
>         struct property *prop;
> -       struct device_node *np = reboot->dev->of_node;
>         size_t len = strlen(PREFIX);
>         int ret;
>
> +       if (!fwnode)
> +               return -EINVAL;
> +
> +       np = to_of_node(fwnode);
> +       if (!np)
> +               return -EINVAL;
> +
>         INIT_LIST_HEAD(&reboot->head);
>
>         mutex_init(&reboot->rb_lock);
> @@ -89,28 +102,28 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
>                         if (strncmp(prop->name, PREFIX, len))
>                                 continue;
>
> -                       info = devm_kzalloc(reboot->dev, sizeof(*info), GFP_KERNEL);

This change is good - devres should not be used in subsystem library
code, only in drivers - but it doesn't seem to belong here, can you
please separate it out and make it backportable?

> +                       info = kzalloc(sizeof(*info), GFP_KERNEL);
>                         if (!info) {
>                                 ret = -ENOMEM;
>                                 goto error;
>                         }
>
>                         if (of_property_read_u32(np, prop->name, &info->magic)) {
> -                               dev_err(reboot->dev, "reboot mode %s without magic number\n",
> -                                       info->mode);
> -                               devm_kfree(reboot->dev, info);
> +                               pr_err("reboot mode %s without magic number\n", info->mode);
> +                               kfree(info);
>                                 continue;
>                         }
>
>                         info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
>                         if (!info->mode) {
>                                 ret =  -ENOMEM;
> +                               kfree(info);
>                                 goto error;
>                         } else if (info->mode[0] == '\0') {
>                                 kfree_const(info->mode);
> +                               kfree(info);
>                                 ret = -EINVAL;
> -                               dev_err(reboot->dev, "invalid mode name(%s): too short!\n",
> -                                       prop->name);
> +                               pr_err("invalid mode name(%s): too short!\n", prop->name);
>                                 goto error;
>                         }
>
> @@ -123,8 +136,11 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
>                 return 0;
>
>  error:
> -               list_for_each_entry(info, &reboot->head, list)
> +               list_for_each_entry_safe(info, next, &reboot->head, list) {
> +                       list_del(&info->list);

Same here, not deleting the entries currently seems like a bug? Do we
depend on the driver detach to clean up the resources on failure?

>                         kfree_const(info->mode);
> +                       kfree(info);
> +               }
>         }
>
>         return ret;
> @@ -138,12 +154,16 @@ EXPORT_SYMBOL_GPL(reboot_mode_register);
>  int reboot_mode_unregister(struct reboot_mode_driver *reboot)
>  {
>         struct mode_info *info;
> +       struct mode_info *next;
>
>         unregister_reboot_notifier(&reboot->reboot_notifier);
>
>         scoped_guard(mutex, &reboot->rb_lock) {
> -               list_for_each_entry(info, &reboot->head, list)
> +               list_for_each_entry_safe(info, next, &reboot->head, list) {
> +                       list_del(&info->list);
>                         kfree_const(info->mode);
> +                       kfree(info);
> +               }
>         }
>
>         return 0;
> @@ -168,11 +188,14 @@ int devm_reboot_mode_register(struct device *dev,
>         struct reboot_mode_driver **dr;
>         int rc;
>
> +       if (!reboot->dev || !reboot->dev->of_node)
> +               return -EINVAL;
> +
>         dr = devres_alloc(devm_reboot_mode_release, sizeof(*dr), GFP_KERNEL);
>         if (!dr)
>                 return -ENOMEM;
>
> -       rc = reboot_mode_register(reboot);
> +       rc = reboot_mode_register(reboot, of_fwnode_handle(reboot->dev->of_node));
>         if (rc) {
>                 devres_free(dr);
>                 return rc;
> diff --git a/include/linux/reboot-mode.h b/include/linux/reboot-mode.h
> index b73f80708197677db8dc2e43affc519782b7146e..7f05fd873e95ca8249bc167c21aa6b76faba7849 100644
> --- a/include/linux/reboot-mode.h
> +++ b/include/linux/reboot-mode.h
> @@ -2,6 +2,7 @@
>  #ifndef __REBOOT_MODE_H__
>  #define __REBOOT_MODE_H__
>
> +#include <linux/fwnode.h>
>  #include <linux/mutex.h>
>
>  struct reboot_mode_driver {
> @@ -13,7 +14,7 @@ struct reboot_mode_driver {
>         struct mutex rb_lock;
>  };
>
> -int reboot_mode_register(struct reboot_mode_driver *reboot);
> +int reboot_mode_register(struct reboot_mode_driver *reboot, struct fwnode_handle *fwnode);
>  int reboot_mode_unregister(struct reboot_mode_driver *reboot);
>  int devm_reboot_mode_register(struct device *dev,
>                               struct reboot_mode_driver *reboot);
>
> --
> 2.34.1
>

Bartosz