// SPDX-License-Identifier: GPL-2.0 /* * class.c - basic device class management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * Copyright (c) 2003-2004 Greg Kroah-Hartman * Copyright (c) 2003-2004 IBM Corp. */ #include <linux/device.h> #include <linux/module.h> #include <linux/init.h> #include <linux/string.h> #include <linux/kdev_t.h> #include <linux/err.h> #include <linux/slab.h> #include <linux/genhd.h> #include <linux/mutex.h> #include "base.h" #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr) static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { struct class_attribute *class_attr = to_class_attr(attr); struct subsys_private *cp = to_subsys_private(kobj); ssize_t ret = -EIO; if (class_attr->show) ret = class_attr->show(cp->class, class_attr, buf); return ret; } static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count) { struct class_attribute *class_attr = to_class_attr(attr); struct subsys_private *cp = to_subsys_private(kobj); ssize_t ret = -EIO; if (class_attr->store) ret = class_attr->store(cp->class, class_attr, buf, count); return ret; } static void class_release(struct kobject *kobj) { struct subsys_private *cp = to_subsys_private(kobj); struct class *class = cp->class; pr_debug("class '%s': release.\n", class->name); if (class->class_release) class->class_release(class); else pr_debug("class '%s' does not have a release() function, " "be careful\n", class->name); kfree(cp); } static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj) { struct subsys_private *cp = to_subsys_private(kobj); struct class *class = cp->class; return class->ns_type; } static const struct sysfs_ops class_sysfs_ops = { .show = class_attr_show, .store = class_attr_store, }; static struct kobj_type class_ktype = { .sysfs_ops = &class_sysfs_ops, .release = class_release, .child_ns_type = class_child_ns_type, }; /* Hotplug events for classes go to the class subsys */ static struct kset *class_kset; int class_create_file_ns(struct class *cls, const struct class_attribute *attr, const void *ns) { int error; if (cls) error = sysfs_create_file_ns(&cls->p->subsys.kobj, &attr->attr, ns); else error = -EINVAL; return error; } void class_remove_file_ns(struct class *cls, const struct class_attribute *attr, const void *ns) { if (cls) sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns); } static struct class *class_get(struct class *cls) { if (cls) kset_get(&cls->p->subsys); return cls; } static void class_put(struct class *cls) { if (cls) kset_put(&cls->p->subsys); } static void klist_class_dev_get(struct klist_node *n) { struct device *dev = container_of(n, struct device, knode_class); get_device(dev); } static void klist_class_dev_put(struct klist_node *n) { struct device *dev = container_of(n, struct device, knode_class); put_device(dev); } static int class_add_groups(struct class *cls, const struct attribute_group **groups) { return sysfs_create_groups(&cls->p->subsys.kobj, groups); } static void class_remove_groups(struct class *cls, const struct attribute_group **groups) { return sysfs_remove_groups(&cls->p->subsys.kobj, groups); } int __class_register(struct class *cls, struct lock_class_key *key) { struct subsys_private *cp; int error; pr_debug("device class '%s': registering\n", cls->name); cp = kzalloc(sizeof(*cp), GFP_KERNEL); if (!cp) return -ENOMEM; klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put); INIT_LIST_HEAD(&cp->interfaces); kset_init(&cp->glue_dirs); __mutex_init(&cp->mutex, "subsys mutex", key); error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name); if (error) { kfree(cp); return error; } /* set the default /sys/dev directory for devices of this class */ if (!cls->dev_kobj) cls->dev_kobj = sysfs_dev_char_kobj; #if defined(CONFIG_BLOCK) /* let the block class directory show up in the root of sysfs */ if (!sysfs_deprecated || cls != &block_class) cp->subsys.kobj.kset = class_kset; #else cp->subsys.kobj.kset = class_kset; #endif cp->subsys.kobj.ktype = &class_ktype; cp->class = cls; cls->p = cp; error = kset_register(&cp->subsys); if (error) { kfree(cp); return error; } error = class_add_groups(class_get(cls), cls->class_groups); class_put(cls); return error; } EXPORT_SYMBOL_GPL(__class_register); void class_unregister(struct class *cls) { pr_debug("device class '%s': unregistering\n", cls->name); class_remove_groups(cls, cls->class_groups); kset_unregister(&cls->p->subsys); } static void class_create_release(struct class *cls) { pr_debug("%s called for %s\n", __func__, cls->name); kfree(cls); } /** * class_create - create a struct class structure * @owner: pointer to the module that is to "own" this struct class * @name: pointer to a string for the name of this class. * @key: the lock_class_key for this class; used by mutex lock debugging * * This is used to create a struct class pointer that can then be used * in calls to device_create(). * * Returns &struct class pointer on success, or ERR_PTR() on error. * * Note, the pointer created here is to be destroyed when finished by * making a call to class_destroy(). */ struct class *__class_create(struct module *owner, const char *name, struct lock_class_key *key) { struct class *cls; int retval; cls = kzalloc(sizeof(*cls), GFP_KERNEL); if (!cls) { retval = -ENOMEM; goto error; } cls->name = name; cls->owner = owner; cls->class_release = class_create_release; retval = __class_register(cls, key); if (retval) goto error; return cls; error: kfree(cls); return ERR_PTR(retval); } EXPORT_SYMBOL_GPL(__class_create); /** * class_destroy - destroys a struct class structure * @cls: pointer to the struct class that is to be destroyed * * Note, the pointer to be destroyed must have been created with a call * to class_create(). */ void class_destroy(struct class *cls) { if ((cls == NULL) || (IS_ERR(cls))) return; class_unregister(cls); } /** * class_dev_iter_init - initialize class device iterator * @iter: class iterator to initialize * @class: the class we wanna iterate over * @start: the device to start iterating from, if any * @type: device_type of the devices to iterate over, NULL for all * * Initialize class iterator @iter such that it iterates over devices * of @class. If @start is set, the list iteration will start there, * otherwise if it is NULL, the iteration starts at the beginning of * the list. */ void class_dev_iter_init(struct class_dev_iter *iter, struct class *class, struct device *start, const struct device_type *type) { struct klist_node *start_knode = NULL; if (start) start_knode = &start->knode_class; klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode); iter->type = type; } EXPORT_SYMBOL_GPL(class_dev_iter_init); /** * class_dev_iter_next - iterate to the next device * @iter: class iterator to proceed * * Proceed @iter to the next device and return it. Returns NULL if * iteration is complete. * * The returned device is referenced and won't be released till * iterator is proceed to the next device or exited. The caller is * free to do whatever it wants to do with the device including * calling back into class code. */ struct device *class_dev_iter_next(struct class_dev_iter *iter) { struct klist_node *knode; struct device *dev; while (1) { knode = klist_next(&iter->ki); if (!knode) return NULL; dev = container_of(knode, struct device, knode_class); if (!iter->type || iter->type == dev->type) return dev; } } EXPORT_SYMBOL_GPL(class_dev_iter_next); /** * class_dev_iter_exit - finish iteration * @iter: class iterator to finish * * Finish an iteration. Always call this function after iteration is * complete whether the iteration ran till the end or not. */ void class_dev_iter_exit(struct class_dev_iter *iter) { klist_iter_exit(&iter->ki); } EXPORT_SYMBOL_GPL(class_dev_iter_exit); /** * class_for_each_device - device iterator * @class: the class we're iterating * @start: the device to start with in the list, if any. * @data: data for the callback * @fn: function to be called for each device * * Iterate over @class's list of devices, and call @fn for each, * passing it @data. If @start is set, the list iteration will start * there, otherwise if it is NULL, the iteration starts at the * beginning of the list. * * We check the return of @fn each time. If it returns anything * other than 0, we break out and return that value. * * @fn is allowed to do anything including calling back into class * code. There's no locking restriction. */ int class_for_each_device(struct class *class, struct device *start, void *data, int (*fn)(struct device *, void *)) { struct class_dev_iter iter; struct device *dev; int error = 0; if (!class) return -EINVAL; if (!class->p) { WARN(1, "%s called for class '%s' before it was initialized", __func__, class->name); return -EINVAL; } class_dev_iter_init(&iter, class, start, NULL); while ((dev = class_dev_iter_next(&iter))) { error = fn(dev, data); if (error) break; } class_dev_iter_exit(&iter); return error; } EXPORT_SYMBOL_GPL(class_for_each_device); /** * class_find_device - device iterator for locating a particular device * @class: the class we're iterating * @start: Device to begin with * @data: data for the match function * @match: function to check device * * This is similar to the class_for_each_dev() function above, but it * returns a reference to a device that is 'found' for later use, as * determined by the @match callback. * * The callback should return 0 if the device doesn't match and non-zero * if it does. If the callback returns non-zero, this function will * return to the caller and not iterate over any more devices. * * Note, you will need to drop the reference with put_device() after use. * * @match is allowed to do anything including calling back into class * code. There's no locking restriction. */ struct device *class_find_device(struct class *class, struct device *start, const void *data, int (*match)(struct device *, const void *)) { struct class_dev_iter iter; struct device *dev; if (!class) return NULL; if (!class->p) { WARN(1, "%s called for class '%s' before it was initialized", __func__, class->name); return NULL; } class_dev_iter_init(&iter, class, start, NULL); while ((dev = class_dev_iter_next(&iter))) { if (match(dev, data)) { get_device(dev); break; } } class_dev_iter_exit(&iter); return dev; } EXPORT_SYMBOL_GPL(class_find_device); int class_interface_register(struct class_interface *class_intf) { struct class *parent; struct class_dev_iter iter; struct device *dev; if (!class_intf || !class_intf->class) return -ENODEV; parent = class_get(class_intf->class); if (!parent) return -EINVAL; mutex_lock(&parent->p->mutex); list_add_tail(&class_intf->node, &parent->p->interfaces); if (class_intf->add_dev) { class_dev_iter_init(&iter, parent, NULL, NULL); while ((dev = class_dev_iter_next(&iter))) class_intf->add_dev(dev, class_intf); class_dev_iter_exit(&iter); } mutex_unlock(&parent->p->mutex); return 0; } void class_interface_unregister(struct class_interface *class_intf) { struct class *parent = class_intf->class; struct class_dev_iter iter; struct device *dev; if (!parent) return; mutex_lock(&parent->p->mutex); list_del_init(&class_intf->node); if (class_intf->remove_dev) { class_dev_iter_init(&iter, parent, NULL, NULL); while ((dev = class_dev_iter_next(&iter))) class_intf->remove_dev(dev, class_intf); class_dev_iter_exit(&iter); } mutex_unlock(&parent->p->mutex); class_put(parent); } ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr, char *buf) { struct class_attribute_string *cs; cs = container_of(attr, struct class_attribute_string, attr); return snprintf(buf, PAGE_SIZE, "%s\n", cs->str); } EXPORT_SYMBOL_GPL(show_class_attr_string); struct class_compat { struct kobject *kobj; }; /** * class_compat_register - register a compatibility class * @name: the name of the class * * Compatibility class are meant as a temporary user-space compatibility * workaround when converting a family of class devices to a bus devices. */ struct class_compat *class_compat_register(const char *name) { struct class_compat *cls; cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL); if (!cls) return NULL; cls->kobj = kobject_create_and_add(name, &class_kset->kobj); if (!cls->kobj) { kfree(cls); return NULL; } return cls; } EXPORT_SYMBOL_GPL(class_compat_register); /** * class_compat_unregister - unregister a compatibility class * @cls: the class to unregister */ void class_compat_unregister(struct class_compat *cls) { kobject_put(cls->kobj); kfree(cls); } EXPORT_SYMBOL_GPL(class_compat_unregister); /** * class_compat_create_link - create a compatibility class device link to * a bus device * @cls: the compatibility class * @dev: the target bus device * @device_link: an optional device to which a "device" link should be created */ int class_compat_create_link(struct class_compat *cls, struct device *dev, struct device *device_link) { int error; error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev)); if (error) return error; /* * Optionally add a "device" link (typically to the parent), as a * class device would have one and we want to provide as much * backwards compatibility as possible. */ if (device_link) { error = sysfs_create_link(&dev->kobj, &device_link->kobj, "device"); if (error) sysfs_remove_link(cls->kobj, dev_name(dev)); } return error; } EXPORT_SYMBOL_GPL(class_compat_create_link); /** * class_compat_remove_link - remove a compatibility class device link to * a bus device * @cls: the compatibility class * @dev: the target bus device * @device_link: an optional device to which a "device" link was previously * created */ void class_compat_remove_link(struct class_compat *cls, struct device *dev, struct device *device_link) { if (device_link) sysfs_remove_link(&dev->kobj, "device"); sysfs_remove_link(cls->kobj, dev_name(dev)); } EXPORT_SYMBOL_GPL(class_compat_remove_link); int __init classes_init(void) { class_kset = kset_create_and_add("class", NULL, NULL); if (!class_kset) return -ENOMEM; return 0; } EXPORT_SYMBOL_GPL(class_create_file_ns); EXPORT_SYMBOL_GPL(class_remove_file_ns); EXPORT_SYMBOL_GPL(class_unregister); EXPORT_SYMBOL_GPL(class_destroy); EXPORT_SYMBOL_GPL(class_interface_register); EXPORT_SYMBOL_GPL(class_interface_unregister);