mirror of https://gitee.com/openkylin/linux.git
200 lines
5.5 KiB
C
200 lines
5.5 KiB
C
/*
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* class_simple.c - a "simple" interface for classes for simple char devices.
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*
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* Copyright (c) 2003-2004 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (c) 2003-2004 IBM Corp.
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*
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* This file is released under the GPLv2
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*
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*/
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#include <linux/config.h>
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#include <linux/device.h>
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#include <linux/err.h>
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struct class_simple {
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struct class class;
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};
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#define to_class_simple(d) container_of(d, struct class_simple, class)
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struct simple_dev {
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struct list_head node;
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struct class_device class_dev;
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};
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#define to_simple_dev(d) container_of(d, struct simple_dev, class_dev)
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static LIST_HEAD(simple_dev_list);
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static DEFINE_SPINLOCK(simple_dev_list_lock);
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static void release_simple_dev(struct class_device *class_dev)
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{
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struct simple_dev *s_dev = to_simple_dev(class_dev);
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kfree(s_dev);
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}
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static void class_simple_release(struct class *class)
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{
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struct class_simple *cs = to_class_simple(class);
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kfree(cs);
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}
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/**
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* class_simple_create - create a struct class_simple structure
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* @owner: pointer to the module that is to "own" this struct class_simple
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* @name: pointer to a string for the name of this class.
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*
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* This is used to create a struct class_simple pointer that can then be used
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* in calls to class_simple_device_add(). This is used when you do not wish to
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* create a full blown class support for a type of char devices.
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*
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* Note, the pointer created here is to be destroyed when finished by making a
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* call to class_simple_destroy().
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*/
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struct class_simple *class_simple_create(struct module *owner, char *name)
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{
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struct class_simple *cs;
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int retval;
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cs = kmalloc(sizeof(*cs), GFP_KERNEL);
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if (!cs) {
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retval = -ENOMEM;
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goto error;
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}
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memset(cs, 0x00, sizeof(*cs));
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cs->class.name = name;
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cs->class.class_release = class_simple_release;
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cs->class.release = release_simple_dev;
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retval = class_register(&cs->class);
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if (retval)
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goto error;
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return cs;
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error:
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kfree(cs);
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return ERR_PTR(retval);
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}
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EXPORT_SYMBOL(class_simple_create);
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/**
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* class_simple_destroy - destroys a struct class_simple structure
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* @cs: pointer to the struct class_simple that is to be destroyed
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*
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* Note, the pointer to be destroyed must have been created with a call to
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* class_simple_create().
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*/
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void class_simple_destroy(struct class_simple *cs)
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{
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if ((cs == NULL) || (IS_ERR(cs)))
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return;
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class_unregister(&cs->class);
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}
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EXPORT_SYMBOL(class_simple_destroy);
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/**
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* class_simple_device_add - adds a class device to sysfs for a character driver
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* @cs: pointer to the struct class_simple that this device should be registered to.
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* @dev: the dev_t for the device to be added.
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* @device: a pointer to a struct device that is assiociated with this class device.
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* @fmt: string for the class device's name
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*
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* This function can be used by simple char device classes that do not
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* implement their own class device registration. A struct class_device will
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* be created in sysfs, registered to the specified class. A "dev" file will
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* be created, showing the dev_t for the device. The pointer to the struct
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* class_device will be returned from the call. Any further sysfs files that
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* might be required can be created using this pointer.
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* Note: the struct class_simple passed to this function must have previously been
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* created with a call to class_simple_create().
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*/
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struct class_device *class_simple_device_add(struct class_simple *cs, dev_t dev, struct device *device, const char *fmt, ...)
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{
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va_list args;
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struct simple_dev *s_dev = NULL;
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int retval;
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if ((cs == NULL) || (IS_ERR(cs))) {
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retval = -ENODEV;
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goto error;
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}
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s_dev = kmalloc(sizeof(*s_dev), GFP_KERNEL);
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if (!s_dev) {
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retval = -ENOMEM;
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goto error;
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}
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memset(s_dev, 0x00, sizeof(*s_dev));
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s_dev->class_dev.devt = dev;
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s_dev->class_dev.dev = device;
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s_dev->class_dev.class = &cs->class;
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va_start(args, fmt);
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vsnprintf(s_dev->class_dev.class_id, BUS_ID_SIZE, fmt, args);
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va_end(args);
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retval = class_device_register(&s_dev->class_dev);
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if (retval)
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goto error;
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spin_lock(&simple_dev_list_lock);
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list_add(&s_dev->node, &simple_dev_list);
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spin_unlock(&simple_dev_list_lock);
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return &s_dev->class_dev;
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error:
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kfree(s_dev);
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return ERR_PTR(retval);
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}
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EXPORT_SYMBOL(class_simple_device_add);
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/**
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* class_simple_set_hotplug - set the hotplug callback in the embedded struct class
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* @cs: pointer to the struct class_simple to hold the pointer
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* @hotplug: function pointer to the hotplug function
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*
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* Implement and set a hotplug function to add environment variables specific to this
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* class on the hotplug event.
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*/
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int class_simple_set_hotplug(struct class_simple *cs,
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int (*hotplug)(struct class_device *dev, char **envp, int num_envp, char *buffer, int buffer_size))
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{
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if ((cs == NULL) || (IS_ERR(cs)))
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return -ENODEV;
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cs->class.hotplug = hotplug;
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return 0;
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}
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EXPORT_SYMBOL(class_simple_set_hotplug);
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/**
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* class_simple_device_remove - removes a class device that was created with class_simple_device_add()
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* @dev: the dev_t of the device that was previously registered.
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*
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* This call unregisters and cleans up a class device that was created with a
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* call to class_device_simple_add()
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*/
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void class_simple_device_remove(dev_t dev)
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{
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struct simple_dev *s_dev = NULL;
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int found = 0;
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spin_lock(&simple_dev_list_lock);
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list_for_each_entry(s_dev, &simple_dev_list, node) {
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if (s_dev->class_dev.devt == dev) {
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found = 1;
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break;
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}
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}
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if (found) {
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list_del(&s_dev->node);
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spin_unlock(&simple_dev_list_lock);
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class_device_unregister(&s_dev->class_dev);
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} else {
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spin_unlock(&simple_dev_list_lock);
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}
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}
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EXPORT_SYMBOL(class_simple_device_remove);
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