From: Shivendra Pratap Date: Tue, 24 Feb 2026 06:42:27 +0000 (+0530) Subject: power: reset: reboot-mode: Expose sysfs for registered reboot_modes X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cfaf0a90789ac74391ac7583c86cdaaada78cdbb;p=thirdparty%2Fkernel%2Flinux.git power: reset: reboot-mode: Expose sysfs for registered reboot_modes Currently, there is no standardized mechanism for userspace to discover supported reboot modes on a platform. This limits userspace scripts, to rely on hardcoded assumptions about the available reboot-modes. Create a class 'reboot-mode' and a device under it. Use the name of the registering driver as device name. Expose a sysfs interface under this device to show available reboot mode arguments. This results in the creation of: /sys/class/reboot-mode//reboot_modes This read-only sysfs file will exposes the supported reboot mode arguments provided by the registering driver, enabling userspace to query the list of arguments. Reviewed-by: Bartosz Golaszewski Signed-off-by: Shivendra Pratap Link: https://patch.msgid.link/20260224-next-15nov_expose_sysfs-v24-2-4ee5b49d5a06@oss.qualcomm.com Signed-off-by: Sebastian Reichel --- diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c index fba53f638da04..ad239e96774b6 100644 --- a/drivers/power/reset/reboot-mode.c +++ b/drivers/power/reset/reboot-mode.c @@ -4,12 +4,16 @@ */ #include +#include #include #include +#include #include #include #include #include +#include +#include #define PREFIX "mode-" @@ -19,6 +23,54 @@ struct mode_info { struct list_head list; }; +struct reboot_mode_sysfs_data { + struct device *reboot_mode_device; + struct list_head head; +}; + +static inline void reboot_mode_release_list(struct reboot_mode_sysfs_data *priv) +{ + struct mode_info *info; + struct mode_info *next; + + list_for_each_entry_safe(info, next, &priv->head, list) { + list_del(&info->list); + kfree_const(info->mode); + kfree(info); + } +} + +static ssize_t reboot_modes_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct reboot_mode_sysfs_data *priv; + struct mode_info *sysfs_info; + ssize_t size = 0; + + priv = dev_get_drvdata(dev); + if (!priv) + return -ENODATA; + + list_for_each_entry(sysfs_info, &priv->head, list) + size += sysfs_emit_at(buf, size, "%s ", sysfs_info->mode); + + if (!size) + return -ENODATA; + + return size + sysfs_emit_at(buf, size - 1, "\n"); +} +static DEVICE_ATTR_RO(reboot_modes); + +static struct attribute *reboot_mode_attrs[] = { + &dev_attr_reboot_modes.attr, + NULL, +}; +ATTRIBUTE_GROUPS(reboot_mode); + +static const struct class reboot_mode_class = { + .name = "reboot-mode", + .dev_groups = reboot_mode_groups, +}; + static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot, const char *cmd) { @@ -62,6 +114,51 @@ static int reboot_mode_notify(struct notifier_block *this, return NOTIFY_DONE; } +static int reboot_mode_create_device(struct reboot_mode_driver *reboot) +{ + struct reboot_mode_sysfs_data *priv; + struct mode_info *sysfs_info; + struct mode_info *info; + int ret; + + priv = kzalloc_obj(*priv, GFP_KERNEL); + if (!priv) + return -ENOMEM; + + INIT_LIST_HEAD(&priv->head); + + list_for_each_entry(info, &reboot->head, list) { + sysfs_info = kzalloc_obj(*sysfs_info, GFP_KERNEL); + if (!sysfs_info) { + ret = -ENOMEM; + goto error; + } + + sysfs_info->mode = kstrdup_const(info->mode, GFP_KERNEL); + if (!sysfs_info->mode) { + kfree(sysfs_info); + ret = -ENOMEM; + goto error; + } + + list_add_tail(&sysfs_info->list, &priv->head); + } + + priv->reboot_mode_device = device_create(&reboot_mode_class, NULL, 0, + (void *)priv, reboot->dev->driver->name); + if (IS_ERR(priv->reboot_mode_device)) { + ret = PTR_ERR(priv->reboot_mode_device); + goto error; + } + + return 0; + +error: + reboot_mode_release_list(priv); + kfree(priv); + return ret; +} + /** * reboot_mode_register - register a reboot mode driver * @reboot: reboot mode driver @@ -113,16 +210,49 @@ int reboot_mode_register(struct reboot_mode_driver *reboot) reboot->reboot_notifier.notifier_call = reboot_mode_notify; register_reboot_notifier(&reboot->reboot_notifier); + ret = reboot_mode_create_device(reboot); + if (ret) + goto error; + return 0; error: - list_for_each_entry(info, &reboot->head, list) - kfree_const(info->mode); - + reboot_mode_unregister(reboot); return ret; } EXPORT_SYMBOL_GPL(reboot_mode_register); +static int reboot_mode_match_by_name(struct device *dev, const void *data) +{ + const char *name = data; + + if (!dev || !data) + return 0; + + return dev_name(dev) && strcmp(dev_name(dev), name) == 0; +} + +static inline void reboot_mode_unregister_device(struct reboot_mode_driver *reboot) +{ + struct reboot_mode_sysfs_data *priv; + struct device *reboot_mode_device; + + reboot_mode_device = class_find_device(&reboot_mode_class, NULL, reboot->dev->driver->name, + reboot_mode_match_by_name); + + if (!reboot_mode_device) + return; + + priv = dev_get_drvdata(reboot_mode_device); + device_unregister(reboot_mode_device); + + if (!priv) + return; + + reboot_mode_release_list(priv); + kfree(priv); +} + /** * reboot_mode_unregister - unregister a reboot mode driver * @reboot: reboot mode driver @@ -132,6 +262,7 @@ int reboot_mode_unregister(struct reboot_mode_driver *reboot) struct mode_info *info; unregister_reboot_notifier(&reboot->reboot_notifier); + reboot_mode_unregister_device(reboot); list_for_each_entry(info, &reboot->head, list) kfree_const(info->mode); @@ -199,6 +330,19 @@ void devm_reboot_mode_unregister(struct device *dev, } EXPORT_SYMBOL_GPL(devm_reboot_mode_unregister); +static int __init reboot_mode_init(void) +{ + return class_register(&reboot_mode_class); +} + +static void __exit reboot_mode_exit(void) +{ + class_unregister(&reboot_mode_class); +} + +subsys_initcall(reboot_mode_init); +module_exit(reboot_mode_exit); + MODULE_AUTHOR("Andy Yan "); MODULE_DESCRIPTION("System reboot mode core library"); MODULE_LICENSE("GPL v2");