| // 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/class.h> |
| #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 struct device *klist_class_to_dev(struct klist_node *n) |
| { |
| struct device_private *p = to_device_private_class(n); |
| return p->device; |
| } |
| |
| static void klist_class_dev_get(struct klist_node *n) |
| { |
| struct device *dev = klist_class_to_dev(n); |
| |
| get_device(dev); |
| } |
| |
| static void klist_class_dev_put(struct klist_node *n) |
| { |
| struct device *dev = klist_class_to_dev(n); |
| |
| 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); |
| if (error) { |
| kobject_del(&cp->subsys.kobj); |
| kfree_const(cp->subsys.kobj.name); |
| kfree(cp); |
| } |
| 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->p->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 = klist_class_to_dev(knode); |
| 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 sysfs_emit(buf, "%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); |