Linux kernel mirror (for testing)
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linux
1/*
2 * class_simple.c - a "simple" interface for classes for simple char devices.
3 *
4 * Copyright (c) 2003-2004 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (c) 2003-2004 IBM Corp.
6 *
7 * This file is released under the GPLv2
8 *
9 */
10
11#include <linux/config.h>
12#include <linux/device.h>
13#include <linux/err.h>
14
15struct class_simple {
16 struct class class;
17};
18#define to_class_simple(d) container_of(d, struct class_simple, class)
19
20struct simple_dev {
21 struct list_head node;
22 struct class_device class_dev;
23};
24#define to_simple_dev(d) container_of(d, struct simple_dev, class_dev)
25
26static LIST_HEAD(simple_dev_list);
27static DEFINE_SPINLOCK(simple_dev_list_lock);
28
29static void release_simple_dev(struct class_device *class_dev)
30{
31 struct simple_dev *s_dev = to_simple_dev(class_dev);
32 kfree(s_dev);
33}
34
35static void class_simple_release(struct class *class)
36{
37 struct class_simple *cs = to_class_simple(class);
38 kfree(cs);
39}
40
41/**
42 * class_simple_create - create a struct class_simple structure
43 * @owner: pointer to the module that is to "own" this struct class_simple
44 * @name: pointer to a string for the name of this class.
45 *
46 * This is used to create a struct class_simple pointer that can then be used
47 * in calls to class_simple_device_add(). This is used when you do not wish to
48 * create a full blown class support for a type of char devices.
49 *
50 * Note, the pointer created here is to be destroyed when finished by making a
51 * call to class_simple_destroy().
52 */
53struct class_simple *class_simple_create(struct module *owner, char *name)
54{
55 struct class_simple *cs;
56 int retval;
57
58 cs = kmalloc(sizeof(*cs), GFP_KERNEL);
59 if (!cs) {
60 retval = -ENOMEM;
61 goto error;
62 }
63 memset(cs, 0x00, sizeof(*cs));
64
65 cs->class.name = name;
66 cs->class.class_release = class_simple_release;
67 cs->class.release = release_simple_dev;
68
69 retval = class_register(&cs->class);
70 if (retval)
71 goto error;
72
73 return cs;
74
75error:
76 kfree(cs);
77 return ERR_PTR(retval);
78}
79EXPORT_SYMBOL(class_simple_create);
80
81/**
82 * class_simple_destroy - destroys a struct class_simple structure
83 * @cs: pointer to the struct class_simple that is to be destroyed
84 *
85 * Note, the pointer to be destroyed must have been created with a call to
86 * class_simple_create().
87 */
88void class_simple_destroy(struct class_simple *cs)
89{
90 if ((cs == NULL) || (IS_ERR(cs)))
91 return;
92
93 class_unregister(&cs->class);
94}
95EXPORT_SYMBOL(class_simple_destroy);
96
97/**
98 * class_simple_device_add - adds a class device to sysfs for a character driver
99 * @cs: pointer to the struct class_simple that this device should be registered to.
100 * @dev: the dev_t for the device to be added.
101 * @device: a pointer to a struct device that is assiociated with this class device.
102 * @fmt: string for the class device's name
103 *
104 * This function can be used by simple char device classes that do not
105 * implement their own class device registration. A struct class_device will
106 * be created in sysfs, registered to the specified class. A "dev" file will
107 * be created, showing the dev_t for the device. The pointer to the struct
108 * class_device will be returned from the call. Any further sysfs files that
109 * might be required can be created using this pointer.
110 * Note: the struct class_simple passed to this function must have previously been
111 * created with a call to class_simple_create().
112 */
113struct class_device *class_simple_device_add(struct class_simple *cs, dev_t dev, struct device *device, const char *fmt, ...)
114{
115 va_list args;
116 struct simple_dev *s_dev = NULL;
117 int retval;
118
119 if ((cs == NULL) || (IS_ERR(cs))) {
120 retval = -ENODEV;
121 goto error;
122 }
123
124 s_dev = kmalloc(sizeof(*s_dev), GFP_KERNEL);
125 if (!s_dev) {
126 retval = -ENOMEM;
127 goto error;
128 }
129 memset(s_dev, 0x00, sizeof(*s_dev));
130
131 s_dev->class_dev.devt = dev;
132 s_dev->class_dev.dev = device;
133 s_dev->class_dev.class = &cs->class;
134
135 va_start(args, fmt);
136 vsnprintf(s_dev->class_dev.class_id, BUS_ID_SIZE, fmt, args);
137 va_end(args);
138 retval = class_device_register(&s_dev->class_dev);
139 if (retval)
140 goto error;
141
142 spin_lock(&simple_dev_list_lock);
143 list_add(&s_dev->node, &simple_dev_list);
144 spin_unlock(&simple_dev_list_lock);
145
146 return &s_dev->class_dev;
147
148error:
149 kfree(s_dev);
150 return ERR_PTR(retval);
151}
152EXPORT_SYMBOL(class_simple_device_add);
153
154/**
155 * class_simple_set_hotplug - set the hotplug callback in the embedded struct class
156 * @cs: pointer to the struct class_simple to hold the pointer
157 * @hotplug: function pointer to the hotplug function
158 *
159 * Implement and set a hotplug function to add environment variables specific to this
160 * class on the hotplug event.
161 */
162int class_simple_set_hotplug(struct class_simple *cs,
163 int (*hotplug)(struct class_device *dev, char **envp, int num_envp, char *buffer, int buffer_size))
164{
165 if ((cs == NULL) || (IS_ERR(cs)))
166 return -ENODEV;
167 cs->class.hotplug = hotplug;
168 return 0;
169}
170EXPORT_SYMBOL(class_simple_set_hotplug);
171
172/**
173 * class_simple_device_remove - removes a class device that was created with class_simple_device_add()
174 * @dev: the dev_t of the device that was previously registered.
175 *
176 * This call unregisters and cleans up a class device that was created with a
177 * call to class_device_simple_add()
178 */
179void class_simple_device_remove(dev_t dev)
180{
181 struct simple_dev *s_dev = NULL;
182 int found = 0;
183
184 spin_lock(&simple_dev_list_lock);
185 list_for_each_entry(s_dev, &simple_dev_list, node) {
186 if (s_dev->class_dev.devt == dev) {
187 found = 1;
188 break;
189 }
190 }
191 if (found) {
192 list_del(&s_dev->node);
193 spin_unlock(&simple_dev_list_lock);
194 class_device_unregister(&s_dev->class_dev);
195 } else {
196 spin_unlock(&simple_dev_list_lock);
197 }
198}
199EXPORT_SYMBOL(class_simple_device_remove);