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1/*
2 * linux/drivers/char/misc.c
3 *
4 * Generic misc open routine by Johan Myreen
5 *
6 * Based on code from Linus
7 *
8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
9 * changes incorporated into 0.97pl4
10 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
11 * See busmouse.c for particulars.
12 *
13 * Made things a lot mode modular - easy to compile in just one or two
14 * of the misc drivers, as they are now completely independent. Linus.
15 *
16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
17 *
18 * Fixed a failing symbol register to free the device registration
19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
20 *
21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
22 *
23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
24 *
25 * Handling of mouse minor numbers for kerneld:
26 * Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
27 * adapted by Bjorn Ekwall <bj0rn@blox.se>
28 * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
29 *
30 * Changes for kmod (from kerneld):
31 * Cyrus Durgin <cider@speakeasy.org>
32 *
33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
34 */
35
36#include <linux/module.h>
37
38#include <linux/fs.h>
39#include <linux/errno.h>
40#include <linux/miscdevice.h>
41#include <linux/kernel.h>
42#include <linux/major.h>
43#include <linux/mutex.h>
44#include <linux/proc_fs.h>
45#include <linux/seq_file.h>
46#include <linux/stat.h>
47#include <linux/init.h>
48#include <linux/device.h>
49#include <linux/tty.h>
50#include <linux/kmod.h>
51#include <linux/gfp.h>
52
53/*
54 * Head entry for the doubly linked miscdevice list
55 */
56static LIST_HEAD(misc_list);
57static DEFINE_MUTEX(misc_mtx);
58
59/*
60 * Assigned numbers, used for dynamic minors
61 */
62#define DYNAMIC_MINORS 64 /* like dynamic majors */
63static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
64
65#ifdef CONFIG_PROC_FS
66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
67{
68 mutex_lock(&misc_mtx);
69 return seq_list_start(&misc_list, *pos);
70}
71
72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
73{
74 return seq_list_next(v, &misc_list, pos);
75}
76
77static void misc_seq_stop(struct seq_file *seq, void *v)
78{
79 mutex_unlock(&misc_mtx);
80}
81
82static int misc_seq_show(struct seq_file *seq, void *v)
83{
84 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
85
86 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
87 return 0;
88}
89
90
91static const struct seq_operations misc_seq_ops = {
92 .start = misc_seq_start,
93 .next = misc_seq_next,
94 .stop = misc_seq_stop,
95 .show = misc_seq_show,
96};
97
98static int misc_seq_open(struct inode *inode, struct file *file)
99{
100 return seq_open(file, &misc_seq_ops);
101}
102
103static const struct file_operations misc_proc_fops = {
104 .owner = THIS_MODULE,
105 .open = misc_seq_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = seq_release,
109};
110#endif
111
112static int misc_open(struct inode * inode, struct file * file)
113{
114 int minor = iminor(inode);
115 struct miscdevice *c;
116 int err = -ENODEV;
117 const struct file_operations *new_fops = NULL;
118
119 mutex_lock(&misc_mtx);
120
121 list_for_each_entry(c, &misc_list, list) {
122 if (c->minor == minor) {
123 new_fops = fops_get(c->fops);
124 break;
125 }
126 }
127
128 if (!new_fops) {
129 mutex_unlock(&misc_mtx);
130 request_module("char-major-%d-%d", MISC_MAJOR, minor);
131 mutex_lock(&misc_mtx);
132
133 list_for_each_entry(c, &misc_list, list) {
134 if (c->minor == minor) {
135 new_fops = fops_get(c->fops);
136 break;
137 }
138 }
139 if (!new_fops)
140 goto fail;
141 }
142
143 /*
144 * Place the miscdevice in the file's
145 * private_data so it can be used by the
146 * file operations, including f_op->open below
147 */
148 file->private_data = c;
149
150 err = 0;
151 replace_fops(file, new_fops);
152 if (file->f_op->open)
153 err = file->f_op->open(inode,file);
154fail:
155 mutex_unlock(&misc_mtx);
156 return err;
157}
158
159static struct class *misc_class;
160
161static const struct file_operations misc_fops = {
162 .owner = THIS_MODULE,
163 .open = misc_open,
164 .llseek = noop_llseek,
165};
166
167/**
168 * misc_register - register a miscellaneous device
169 * @misc: device structure
170 *
171 * Register a miscellaneous device with the kernel. If the minor
172 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
173 * and placed in the minor field of the structure. For other cases
174 * the minor number requested is used.
175 *
176 * The structure passed is linked into the kernel and may not be
177 * destroyed until it has been unregistered. By default, an open()
178 * syscall to the device sets file->private_data to point to the
179 * structure. Drivers don't need open in fops for this.
180 *
181 * A zero is returned on success and a negative errno code for
182 * failure.
183 */
184
185int misc_register(struct miscdevice * misc)
186{
187 dev_t dev;
188 int err = 0;
189 bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);
190
191 INIT_LIST_HEAD(&misc->list);
192
193 mutex_lock(&misc_mtx);
194
195 if (is_dynamic) {
196 int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
197 if (i >= DYNAMIC_MINORS) {
198 err = -EBUSY;
199 goto out;
200 }
201 misc->minor = DYNAMIC_MINORS - i - 1;
202 set_bit(i, misc_minors);
203 } else {
204 struct miscdevice *c;
205
206 list_for_each_entry(c, &misc_list, list) {
207 if (c->minor == misc->minor) {
208 err = -EBUSY;
209 goto out;
210 }
211 }
212 }
213
214 dev = MKDEV(MISC_MAJOR, misc->minor);
215
216 misc->this_device =
217 device_create_with_groups(misc_class, misc->parent, dev,
218 misc, misc->groups, "%s", misc->name);
219 if (IS_ERR(misc->this_device)) {
220 if (is_dynamic) {
221 int i = DYNAMIC_MINORS - misc->minor - 1;
222
223 if (i < DYNAMIC_MINORS && i >= 0)
224 clear_bit(i, misc_minors);
225 misc->minor = MISC_DYNAMIC_MINOR;
226 }
227 err = PTR_ERR(misc->this_device);
228 goto out;
229 }
230
231 /*
232 * Add it to the front, so that later devices can "override"
233 * earlier defaults
234 */
235 list_add(&misc->list, &misc_list);
236 out:
237 mutex_unlock(&misc_mtx);
238 return err;
239}
240
241/**
242 * misc_deregister - unregister a miscellaneous device
243 * @misc: device to unregister
244 *
245 * Unregister a miscellaneous device that was previously
246 * successfully registered with misc_register().
247 */
248
249void misc_deregister(struct miscdevice *misc)
250{
251 int i = DYNAMIC_MINORS - misc->minor - 1;
252
253 if (WARN_ON(list_empty(&misc->list)))
254 return;
255
256 mutex_lock(&misc_mtx);
257 list_del(&misc->list);
258 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
259 if (i < DYNAMIC_MINORS && i >= 0)
260 clear_bit(i, misc_minors);
261 mutex_unlock(&misc_mtx);
262}
263
264EXPORT_SYMBOL(misc_register);
265EXPORT_SYMBOL(misc_deregister);
266
267static char *misc_devnode(struct device *dev, umode_t *mode)
268{
269 struct miscdevice *c = dev_get_drvdata(dev);
270
271 if (mode && c->mode)
272 *mode = c->mode;
273 if (c->nodename)
274 return kstrdup(c->nodename, GFP_KERNEL);
275 return NULL;
276}
277
278static int __init misc_init(void)
279{
280 int err;
281 struct proc_dir_entry *ret;
282
283 ret = proc_create("misc", 0, NULL, &misc_proc_fops);
284 misc_class = class_create(THIS_MODULE, "misc");
285 err = PTR_ERR(misc_class);
286 if (IS_ERR(misc_class))
287 goto fail_remove;
288
289 err = -EIO;
290 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
291 goto fail_printk;
292 misc_class->devnode = misc_devnode;
293 return 0;
294
295fail_printk:
296 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
297 class_destroy(misc_class);
298fail_remove:
299 if (ret)
300 remove_proc_entry("misc", NULL);
301 return err;
302}
303subsys_initcall(misc_init);
1/*
2 * linux/drivers/char/misc.c
3 *
4 * Generic misc open routine by Johan Myreen
5 *
6 * Based on code from Linus
7 *
8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
9 * changes incorporated into 0.97pl4
10 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
11 * See busmouse.c for particulars.
12 *
13 * Made things a lot mode modular - easy to compile in just one or two
14 * of the misc drivers, as they are now completely independent. Linus.
15 *
16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
17 *
18 * Fixed a failing symbol register to free the device registration
19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
20 *
21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
22 *
23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
24 *
25 * Handling of mouse minor numbers for kerneld:
26 * Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
27 * adapted by Bjorn Ekwall <bj0rn@blox.se>
28 * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
29 *
30 * Changes for kmod (from kerneld):
31 * Cyrus Durgin <cider@speakeasy.org>
32 *
33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
34 */
35
36#include <linux/module.h>
37
38#include <linux/fs.h>
39#include <linux/errno.h>
40#include <linux/miscdevice.h>
41#include <linux/kernel.h>
42#include <linux/major.h>
43#include <linux/mutex.h>
44#include <linux/proc_fs.h>
45#include <linux/seq_file.h>
46#include <linux/stat.h>
47#include <linux/init.h>
48#include <linux/device.h>
49#include <linux/tty.h>
50#include <linux/kmod.h>
51#include <linux/gfp.h>
52
53/*
54 * Head entry for the doubly linked miscdevice list
55 */
56static LIST_HEAD(misc_list);
57static DEFINE_MUTEX(misc_mtx);
58
59/*
60 * Assigned numbers, used for dynamic minors
61 */
62#define DYNAMIC_MINORS 64 /* like dynamic majors */
63static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
64
65#ifdef CONFIG_PROC_FS
66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
67{
68 mutex_lock(&misc_mtx);
69 return seq_list_start(&misc_list, *pos);
70}
71
72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
73{
74 return seq_list_next(v, &misc_list, pos);
75}
76
77static void misc_seq_stop(struct seq_file *seq, void *v)
78{
79 mutex_unlock(&misc_mtx);
80}
81
82static int misc_seq_show(struct seq_file *seq, void *v)
83{
84 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
85
86 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
87 return 0;
88}
89
90
91static const struct seq_operations misc_seq_ops = {
92 .start = misc_seq_start,
93 .next = misc_seq_next,
94 .stop = misc_seq_stop,
95 .show = misc_seq_show,
96};
97
98static int misc_seq_open(struct inode *inode, struct file *file)
99{
100 return seq_open(file, &misc_seq_ops);
101}
102
103static const struct file_operations misc_proc_fops = {
104 .owner = THIS_MODULE,
105 .open = misc_seq_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = seq_release,
109};
110#endif
111
112static int misc_open(struct inode * inode, struct file * file)
113{
114 int minor = iminor(inode);
115 struct miscdevice *c;
116 int err = -ENODEV;
117 const struct file_operations *new_fops = NULL;
118
119 mutex_lock(&misc_mtx);
120
121 list_for_each_entry(c, &misc_list, list) {
122 if (c->minor == minor) {
123 new_fops = fops_get(c->fops);
124 break;
125 }
126 }
127
128 if (!new_fops) {
129 mutex_unlock(&misc_mtx);
130 request_module("char-major-%d-%d", MISC_MAJOR, minor);
131 mutex_lock(&misc_mtx);
132
133 list_for_each_entry(c, &misc_list, list) {
134 if (c->minor == minor) {
135 new_fops = fops_get(c->fops);
136 break;
137 }
138 }
139 if (!new_fops)
140 goto fail;
141 }
142
143 err = 0;
144 replace_fops(file, new_fops);
145 if (file->f_op->open) {
146 file->private_data = c;
147 err = file->f_op->open(inode,file);
148 }
149fail:
150 mutex_unlock(&misc_mtx);
151 return err;
152}
153
154static struct class *misc_class;
155
156static const struct file_operations misc_fops = {
157 .owner = THIS_MODULE,
158 .open = misc_open,
159 .llseek = noop_llseek,
160};
161
162/**
163 * misc_register - register a miscellaneous device
164 * @misc: device structure
165 *
166 * Register a miscellaneous device with the kernel. If the minor
167 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
168 * and placed in the minor field of the structure. For other cases
169 * the minor number requested is used.
170 *
171 * The structure passed is linked into the kernel and may not be
172 * destroyed until it has been unregistered.
173 *
174 * A zero is returned on success and a negative errno code for
175 * failure.
176 */
177
178int misc_register(struct miscdevice * misc)
179{
180 dev_t dev;
181 int err = 0;
182
183 INIT_LIST_HEAD(&misc->list);
184
185 mutex_lock(&misc_mtx);
186
187 if (misc->minor == MISC_DYNAMIC_MINOR) {
188 int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
189 if (i >= DYNAMIC_MINORS) {
190 err = -EBUSY;
191 goto out;
192 }
193 misc->minor = DYNAMIC_MINORS - i - 1;
194 set_bit(i, misc_minors);
195 } else {
196 struct miscdevice *c;
197
198 list_for_each_entry(c, &misc_list, list) {
199 if (c->minor == misc->minor) {
200 err = -EBUSY;
201 goto out;
202 }
203 }
204 }
205
206 dev = MKDEV(MISC_MAJOR, misc->minor);
207
208 misc->this_device = device_create(misc_class, misc->parent, dev,
209 misc, "%s", misc->name);
210 if (IS_ERR(misc->this_device)) {
211 int i = DYNAMIC_MINORS - misc->minor - 1;
212 if (i < DYNAMIC_MINORS && i >= 0)
213 clear_bit(i, misc_minors);
214 err = PTR_ERR(misc->this_device);
215 goto out;
216 }
217
218 /*
219 * Add it to the front, so that later devices can "override"
220 * earlier defaults
221 */
222 list_add(&misc->list, &misc_list);
223 out:
224 mutex_unlock(&misc_mtx);
225 return err;
226}
227
228/**
229 * misc_deregister - unregister a miscellaneous device
230 * @misc: device to unregister
231 *
232 * Unregister a miscellaneous device that was previously
233 * successfully registered with misc_register(). Success
234 * is indicated by a zero return, a negative errno code
235 * indicates an error.
236 */
237
238int misc_deregister(struct miscdevice *misc)
239{
240 int i = DYNAMIC_MINORS - misc->minor - 1;
241
242 if (WARN_ON(list_empty(&misc->list)))
243 return -EINVAL;
244
245 mutex_lock(&misc_mtx);
246 list_del(&misc->list);
247 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
248 if (i < DYNAMIC_MINORS && i >= 0)
249 clear_bit(i, misc_minors);
250 mutex_unlock(&misc_mtx);
251 return 0;
252}
253
254EXPORT_SYMBOL(misc_register);
255EXPORT_SYMBOL(misc_deregister);
256
257static char *misc_devnode(struct device *dev, umode_t *mode)
258{
259 struct miscdevice *c = dev_get_drvdata(dev);
260
261 if (mode && c->mode)
262 *mode = c->mode;
263 if (c->nodename)
264 return kstrdup(c->nodename, GFP_KERNEL);
265 return NULL;
266}
267
268static int __init misc_init(void)
269{
270 int err;
271
272#ifdef CONFIG_PROC_FS
273 proc_create("misc", 0, NULL, &misc_proc_fops);
274#endif
275 misc_class = class_create(THIS_MODULE, "misc");
276 err = PTR_ERR(misc_class);
277 if (IS_ERR(misc_class))
278 goto fail_remove;
279
280 err = -EIO;
281 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
282 goto fail_printk;
283 misc_class->devnode = misc_devnode;
284 return 0;
285
286fail_printk:
287 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
288 class_destroy(misc_class);
289fail_remove:
290 remove_proc_entry("misc", NULL);
291 return err;
292}
293subsys_initcall(misc_init);