diff options
Diffstat (limited to 'drivers/base/attribute_container.c')
| -rw-r--r-- | drivers/base/attribute_container.c | 544 |
1 files changed, 544 insertions, 0 deletions
diff --git a/drivers/base/attribute_container.c b/drivers/base/attribute_container.c new file mode 100644 index 000000000..f7bd0f4db --- /dev/null +++ b/drivers/base/attribute_container.c @@ -0,0 +1,544 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * attribute_container.c - implementation of a simple container for classes + * + * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com> + * + * The basic idea here is to enable a device to be attached to an + * aritrary numer of classes without having to allocate storage for them. + * Instead, the contained classes select the devices they need to attach + * to via a matching function. + */ + +#include <linux/attribute_container.h> +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> + +#include "base.h" + +/* This is a private structure used to tie the classdev and the + * container .. it should never be visible outside this file */ +struct internal_container { + struct klist_node node; + struct attribute_container *cont; + struct device classdev; +}; + +static void internal_container_klist_get(struct klist_node *n) +{ + struct internal_container *ic = + container_of(n, struct internal_container, node); + get_device(&ic->classdev); +} + +static void internal_container_klist_put(struct klist_node *n) +{ + struct internal_container *ic = + container_of(n, struct internal_container, node); + put_device(&ic->classdev); +} + + +/** + * attribute_container_classdev_to_container - given a classdev, return the container + * + * @classdev: the class device created by attribute_container_add_device. + * + * Returns the container associated with this classdev. + */ +struct attribute_container * +attribute_container_classdev_to_container(struct device *classdev) +{ + struct internal_container *ic = + container_of(classdev, struct internal_container, classdev); + return ic->cont; +} +EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container); + +static LIST_HEAD(attribute_container_list); + +static DEFINE_MUTEX(attribute_container_mutex); + +/** + * attribute_container_register - register an attribute container + * + * @cont: The container to register. This must be allocated by the + * callee and should also be zeroed by it. + */ +int +attribute_container_register(struct attribute_container *cont) +{ + INIT_LIST_HEAD(&cont->node); + klist_init(&cont->containers, internal_container_klist_get, + internal_container_klist_put); + + mutex_lock(&attribute_container_mutex); + list_add_tail(&cont->node, &attribute_container_list); + mutex_unlock(&attribute_container_mutex); + + return 0; +} +EXPORT_SYMBOL_GPL(attribute_container_register); + +/** + * attribute_container_unregister - remove a container registration + * + * @cont: previously registered container to remove + */ +int +attribute_container_unregister(struct attribute_container *cont) +{ + int retval = -EBUSY; + + mutex_lock(&attribute_container_mutex); + spin_lock(&cont->containers.k_lock); + if (!list_empty(&cont->containers.k_list)) + goto out; + retval = 0; + list_del(&cont->node); + out: + spin_unlock(&cont->containers.k_lock); + mutex_unlock(&attribute_container_mutex); + return retval; + +} +EXPORT_SYMBOL_GPL(attribute_container_unregister); + +/* private function used as class release */ +static void attribute_container_release(struct device *classdev) +{ + struct internal_container *ic + = container_of(classdev, struct internal_container, classdev); + struct device *dev = classdev->parent; + + kfree(ic); + put_device(dev); +} + +/** + * attribute_container_add_device - see if any container is interested in dev + * + * @dev: device to add attributes to + * @fn: function to trigger addition of class device. + * + * This function allocates storage for the class device(s) to be + * attached to dev (one for each matching attribute_container). If no + * fn is provided, the code will simply register the class device via + * device_add. If a function is provided, it is expected to add + * the class device at the appropriate time. One of the things that + * might be necessary is to allocate and initialise the classdev and + * then add it a later time. To do this, call this routine for + * allocation and initialisation and then use + * attribute_container_device_trigger() to call device_add() on + * it. Note: after this, the class device contains a reference to dev + * which is not relinquished until the release of the classdev. + */ +void +attribute_container_add_device(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *, + struct device *)) +{ + struct attribute_container *cont; + + mutex_lock(&attribute_container_mutex); + list_for_each_entry(cont, &attribute_container_list, node) { + struct internal_container *ic; + + if (attribute_container_no_classdevs(cont)) + continue; + + if (!cont->match(cont, dev)) + continue; + + ic = kzalloc(sizeof(*ic), GFP_KERNEL); + if (!ic) { + dev_err(dev, "failed to allocate class container\n"); + continue; + } + + ic->cont = cont; + device_initialize(&ic->classdev); + ic->classdev.parent = get_device(dev); + ic->classdev.class = cont->class; + cont->class->dev_release = attribute_container_release; + dev_set_name(&ic->classdev, "%s", dev_name(dev)); + if (fn) + fn(cont, dev, &ic->classdev); + else + attribute_container_add_class_device(&ic->classdev); + klist_add_tail(&ic->node, &cont->containers); + } + mutex_unlock(&attribute_container_mutex); +} + +/* FIXME: can't break out of this unless klist_iter_exit is also + * called before doing the break + */ +#define klist_for_each_entry(pos, head, member, iter) \ + for (klist_iter_init(head, iter); (pos = ({ \ + struct klist_node *n = klist_next(iter); \ + n ? container_of(n, typeof(*pos), member) : \ + ({ klist_iter_exit(iter) ; NULL; }); \ + })) != NULL;) + + +/** + * attribute_container_remove_device - make device eligible for removal. + * + * @dev: The generic device + * @fn: A function to call to remove the device + * + * This routine triggers device removal. If fn is NULL, then it is + * simply done via device_unregister (note that if something + * still has a reference to the classdev, then the memory occupied + * will not be freed until the classdev is released). If you want a + * two phase release: remove from visibility and then delete the + * device, then you should use this routine with a fn that calls + * device_del() and then use attribute_container_device_trigger() + * to do the final put on the classdev. + */ +void +attribute_container_remove_device(struct device *dev, + void (*fn)(struct attribute_container *, + struct device *, + struct device *)) +{ + struct attribute_container *cont; + + mutex_lock(&attribute_container_mutex); + list_for_each_entry(cont, &attribute_container_list, node) { + struct internal_container *ic; + struct klist_iter iter; + + if (attribute_container_no_classdevs(cont)) + continue; + + if (!cont->match(cont, dev)) + continue; + + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (dev != ic->classdev.parent) + continue; + klist_del(&ic->node); + if (fn) + fn(cont, dev, &ic->classdev); + else { + attribute_container_remove_attrs(&ic->classdev); + device_unregister(&ic->classdev); + } + } + } + mutex_unlock(&attribute_container_mutex); +} + +static int +do_attribute_container_device_trigger_safe(struct device *dev, + struct attribute_container *cont, + int (*fn)(struct attribute_container *, + struct device *, struct device *), + int (*undo)(struct attribute_container *, + struct device *, struct device *)) +{ + int ret; + struct internal_container *ic, *failed; + struct klist_iter iter; + + if (attribute_container_no_classdevs(cont)) + return fn(cont, dev, NULL); + + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (dev == ic->classdev.parent) { + ret = fn(cont, dev, &ic->classdev); + if (ret) { + failed = ic; + klist_iter_exit(&iter); + goto fail; + } + } + } + return 0; + +fail: + if (!undo) + return ret; + + /* Attempt to undo the work partially done. */ + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (ic == failed) { + klist_iter_exit(&iter); + break; + } + if (dev == ic->classdev.parent) + undo(cont, dev, &ic->classdev); + } + return ret; +} + +/** + * attribute_container_device_trigger_safe - execute a trigger for each + * matching classdev or fail all of them. + * + * @dev: The generic device to run the trigger for + * @fn the function to execute for each classdev. + * @undo A function to undo the work previously done in case of error + * + * This function is a safe version of + * attribute_container_device_trigger. It stops on the first error and + * undo the partial work that has been done, on previous classdev. It + * is guaranteed that either they all succeeded, or none of them + * succeeded. + */ +int +attribute_container_device_trigger_safe(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *, + struct device *), + int (*undo)(struct attribute_container *, + struct device *, + struct device *)) +{ + struct attribute_container *cont, *failed = NULL; + int ret = 0; + + mutex_lock(&attribute_container_mutex); + + list_for_each_entry(cont, &attribute_container_list, node) { + + if (!cont->match(cont, dev)) + continue; + + ret = do_attribute_container_device_trigger_safe(dev, cont, + fn, undo); + if (ret) { + failed = cont; + break; + } + } + + if (ret && !WARN_ON(!undo)) { + list_for_each_entry(cont, &attribute_container_list, node) { + + if (failed == cont) + break; + + if (!cont->match(cont, dev)) + continue; + + do_attribute_container_device_trigger_safe(dev, cont, + undo, NULL); + } + } + + mutex_unlock(&attribute_container_mutex); + return ret; + +} + +/** + * attribute_container_device_trigger - execute a trigger for each matching classdev + * + * @dev: The generic device to run the trigger for + * @fn the function to execute for each classdev. + * + * This function is for executing a trigger when you need to know both + * the container and the classdev. If you only care about the + * container, then use attribute_container_trigger() instead. + */ +void +attribute_container_device_trigger(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *, + struct device *)) +{ + struct attribute_container *cont; + + mutex_lock(&attribute_container_mutex); + list_for_each_entry(cont, &attribute_container_list, node) { + struct internal_container *ic; + struct klist_iter iter; + + if (!cont->match(cont, dev)) + continue; + + if (attribute_container_no_classdevs(cont)) { + fn(cont, dev, NULL); + continue; + } + + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (dev == ic->classdev.parent) + fn(cont, dev, &ic->classdev); + } + } + mutex_unlock(&attribute_container_mutex); +} + +/** + * attribute_container_trigger - trigger a function for each matching container + * + * @dev: The generic device to activate the trigger for + * @fn: the function to trigger + * + * This routine triggers a function that only needs to know the + * matching containers (not the classdev) associated with a device. + * It is more lightweight than attribute_container_device_trigger, so + * should be used in preference unless the triggering function + * actually needs to know the classdev. + */ +void +attribute_container_trigger(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *)) +{ + struct attribute_container *cont; + + mutex_lock(&attribute_container_mutex); + list_for_each_entry(cont, &attribute_container_list, node) { + if (cont->match(cont, dev)) + fn(cont, dev); + } + mutex_unlock(&attribute_container_mutex); +} + +/** + * attribute_container_add_attrs - add attributes + * + * @classdev: The class device + * + * This simply creates all the class device sysfs files from the + * attributes listed in the container + */ +int +attribute_container_add_attrs(struct device *classdev) +{ + struct attribute_container *cont = + attribute_container_classdev_to_container(classdev); + struct device_attribute **attrs = cont->attrs; + int i, error; + + BUG_ON(attrs && cont->grp); + + if (!attrs && !cont->grp) + return 0; + + if (cont->grp) + return sysfs_create_group(&classdev->kobj, cont->grp); + + for (i = 0; attrs[i]; i++) { + sysfs_attr_init(&attrs[i]->attr); + error = device_create_file(classdev, attrs[i]); + if (error) + return error; + } + + return 0; +} + +/** + * attribute_container_add_class_device - same function as device_add + * + * @classdev: the class device to add + * + * This performs essentially the same function as device_add except for + * attribute containers, namely add the classdev to the system and then + * create the attribute files + */ +int +attribute_container_add_class_device(struct device *classdev) +{ + int error = device_add(classdev); + + if (error) + return error; + return attribute_container_add_attrs(classdev); +} + +/** + * attribute_container_add_class_device_adapter - simple adapter for triggers + * + * This function is identical to attribute_container_add_class_device except + * that it is designed to be called from the triggers + */ +int +attribute_container_add_class_device_adapter(struct attribute_container *cont, + struct device *dev, + struct device *classdev) +{ + return attribute_container_add_class_device(classdev); +} + +/** + * attribute_container_remove_attrs - remove any attribute files + * + * @classdev: The class device to remove the files from + * + */ +void +attribute_container_remove_attrs(struct device *classdev) +{ + struct attribute_container *cont = + attribute_container_classdev_to_container(classdev); + struct device_attribute **attrs = cont->attrs; + int i; + + if (!attrs && !cont->grp) + return; + + if (cont->grp) { + sysfs_remove_group(&classdev->kobj, cont->grp); + return ; + } + + for (i = 0; attrs[i]; i++) + device_remove_file(classdev, attrs[i]); +} + +/** + * attribute_container_class_device_del - equivalent of class_device_del + * + * @classdev: the class device + * + * This function simply removes all the attribute files and then calls + * device_del. + */ +void +attribute_container_class_device_del(struct device *classdev) +{ + attribute_container_remove_attrs(classdev); + device_del(classdev); +} + +/** + * attribute_container_find_class_device - find the corresponding class_device + * + * @cont: the container + * @dev: the generic device + * + * Looks up the device in the container's list of class devices and returns + * the corresponding class_device. + */ +struct device * +attribute_container_find_class_device(struct attribute_container *cont, + struct device *dev) +{ + struct device *cdev = NULL; + struct internal_container *ic; + struct klist_iter iter; + + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (ic->classdev.parent == dev) { + cdev = &ic->classdev; + /* FIXME: must exit iterator then break */ + klist_iter_exit(&iter); + break; + } + } + + return cdev; +} +EXPORT_SYMBOL_GPL(attribute_container_find_class_device); |