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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/drivers/char/misc.c | |
4 | * | |
5 | * Generic misc open routine by Johan Myreen | |
6 | * | |
7 | * Based on code from Linus | |
8 | * | |
9 | * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's | |
10 | * changes incorporated into 0.97pl4 | |
11 | * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) | |
12 | * See busmouse.c for particulars. | |
13 | * | |
14 | * Made things a lot mode modular - easy to compile in just one or two | |
15 | * of the misc drivers, as they are now completely independent. Linus. | |
16 | * | |
17 | * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk> | |
18 | * | |
19 | * Fixed a failing symbol register to free the device registration | |
20 | * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96 | |
21 | * | |
22 | * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 | |
23 | * | |
24 | * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 | |
25 | * | |
26 | * Handling of mouse minor numbers for kerneld: | |
27 | * Idea by Jacques Gelinas <jack@solucorp.qc.ca>, | |
28 | * adapted by Bjorn Ekwall <bj0rn@blox.se> | |
29 | * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk> | |
30 | * | |
31 | * Changes for kmod (from kerneld): | |
32 | * Cyrus Durgin <cider@speakeasy.org> | |
33 | * | |
34 | * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998 | |
35 | */ | |
36 | ||
37 | #include <linux/module.h> | |
1da177e4 LT |
38 | |
39 | #include <linux/fs.h> | |
40 | #include <linux/errno.h> | |
41 | #include <linux/miscdevice.h> | |
42 | #include <linux/kernel.h> | |
43 | #include <linux/major.h> | |
0e82d5b6 | 44 | #include <linux/mutex.h> |
1da177e4 LT |
45 | #include <linux/proc_fs.h> |
46 | #include <linux/seq_file.h> | |
1da177e4 LT |
47 | #include <linux/stat.h> |
48 | #include <linux/init.h> | |
49 | #include <linux/device.h> | |
50 | #include <linux/tty.h> | |
51 | #include <linux/kmod.h> | |
5a0e3ad6 | 52 | #include <linux/gfp.h> |
1da177e4 LT |
53 | |
54 | /* | |
55 | * Head entry for the doubly linked miscdevice list | |
56 | */ | |
57 | static LIST_HEAD(misc_list); | |
0e82d5b6 | 58 | static DEFINE_MUTEX(misc_mtx); |
1da177e4 LT |
59 | |
60 | /* | |
61 | * Assigned numbers, used for dynamic minors | |
62 | */ | |
63 | #define DYNAMIC_MINORS 64 /* like dynamic majors */ | |
1f2f38d8 | 64 | static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS); |
1da177e4 | 65 | |
1da177e4 LT |
66 | #ifdef CONFIG_PROC_FS |
67 | static void *misc_seq_start(struct seq_file *seq, loff_t *pos) | |
68 | { | |
0e82d5b6 | 69 | mutex_lock(&misc_mtx); |
46c65b71 | 70 | return seq_list_start(&misc_list, *pos); |
1da177e4 LT |
71 | } |
72 | ||
73 | static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
74 | { | |
46c65b71 | 75 | return seq_list_next(v, &misc_list, pos); |
1da177e4 LT |
76 | } |
77 | ||
78 | static void misc_seq_stop(struct seq_file *seq, void *v) | |
79 | { | |
0e82d5b6 | 80 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
81 | } |
82 | ||
83 | static int misc_seq_show(struct seq_file *seq, void *v) | |
84 | { | |
46c65b71 | 85 | const struct miscdevice *p = list_entry(v, struct miscdevice, list); |
1da177e4 LT |
86 | |
87 | seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); | |
88 | return 0; | |
89 | } | |
90 | ||
91 | ||
88e9d34c | 92 | static const struct seq_operations misc_seq_ops = { |
1da177e4 LT |
93 | .start = misc_seq_start, |
94 | .next = misc_seq_next, | |
95 | .stop = misc_seq_stop, | |
96 | .show = misc_seq_show, | |
97 | }; | |
98 | ||
99 | static int misc_seq_open(struct inode *inode, struct file *file) | |
100 | { | |
101 | return seq_open(file, &misc_seq_ops); | |
102 | } | |
103 | ||
62322d25 | 104 | static const struct file_operations misc_proc_fops = { |
1da177e4 LT |
105 | .owner = THIS_MODULE, |
106 | .open = misc_seq_open, | |
107 | .read = seq_read, | |
108 | .llseek = seq_lseek, | |
109 | .release = seq_release, | |
110 | }; | |
111 | #endif | |
112 | ||
65ebd3df | 113 | static int misc_open(struct inode *inode, struct file *file) |
1da177e4 LT |
114 | { |
115 | int minor = iminor(inode); | |
116 | struct miscdevice *c; | |
117 | int err = -ENODEV; | |
e84f9e57 | 118 | const struct file_operations *new_fops = NULL; |
40b798ef | 119 | |
0e82d5b6 | 120 | mutex_lock(&misc_mtx); |
898bc282 | 121 | |
1da177e4 LT |
122 | list_for_each_entry(c, &misc_list, list) { |
123 | if (c->minor == minor) { | |
898bc282 | 124 | new_fops = fops_get(c->fops); |
1da177e4 LT |
125 | break; |
126 | } | |
127 | } | |
898bc282 | 128 | |
1da177e4 | 129 | if (!new_fops) { |
0e82d5b6 | 130 | mutex_unlock(&misc_mtx); |
1da177e4 | 131 | request_module("char-major-%d-%d", MISC_MAJOR, minor); |
0e82d5b6 | 132 | mutex_lock(&misc_mtx); |
1da177e4 LT |
133 | |
134 | list_for_each_entry(c, &misc_list, list) { | |
135 | if (c->minor == minor) { | |
136 | new_fops = fops_get(c->fops); | |
137 | break; | |
138 | } | |
139 | } | |
140 | if (!new_fops) | |
141 | goto fail; | |
142 | } | |
143 | ||
0b509d8d TVB |
144 | /* |
145 | * Place the miscdevice in the file's | |
146 | * private_data so it can be used by the | |
147 | * file operations, including f_op->open below | |
148 | */ | |
149 | file->private_data = c; | |
150 | ||
1da177e4 | 151 | err = 0; |
e84f9e57 | 152 | replace_fops(file, new_fops); |
0b509d8d | 153 | if (file->f_op->open) |
50a5e314 | 154 | err = file->f_op->open(inode, file); |
1da177e4 | 155 | fail: |
0e82d5b6 | 156 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
157 | return err; |
158 | } | |
159 | ||
ca8eca68 | 160 | static struct class *misc_class; |
1da177e4 | 161 | |
62322d25 | 162 | static const struct file_operations misc_fops = { |
1da177e4 LT |
163 | .owner = THIS_MODULE, |
164 | .open = misc_open, | |
6038f373 | 165 | .llseek = noop_llseek, |
1da177e4 LT |
166 | }; |
167 | ||
1da177e4 LT |
168 | /** |
169 | * misc_register - register a miscellaneous device | |
170 | * @misc: device structure | |
898bc282 | 171 | * |
1da177e4 LT |
172 | * Register a miscellaneous device with the kernel. If the minor |
173 | * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned | |
174 | * and placed in the minor field of the structure. For other cases | |
175 | * the minor number requested is used. | |
176 | * | |
177 | * The structure passed is linked into the kernel and may not be | |
03190c67 MK |
178 | * destroyed until it has been unregistered. By default, an open() |
179 | * syscall to the device sets file->private_data to point to the | |
180 | * structure. Drivers don't need open in fops for this. | |
1da177e4 LT |
181 | * |
182 | * A zero is returned on success and a negative errno code for | |
183 | * failure. | |
184 | */ | |
898bc282 | 185 | |
65ebd3df | 186 | int misc_register(struct miscdevice *misc) |
1da177e4 | 187 | { |
1da177e4 | 188 | dev_t dev; |
7c69ef79 | 189 | int err = 0; |
b575f712 | 190 | bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR); |
1da177e4 | 191 | |
5d469ec0 NH |
192 | INIT_LIST_HEAD(&misc->list); |
193 | ||
0e82d5b6 | 194 | mutex_lock(&misc_mtx); |
1da177e4 | 195 | |
b575f712 | 196 | if (is_dynamic) { |
1f2f38d8 | 197 | int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS); |
5b884a95 | 198 | |
1f2f38d8 | 199 | if (i >= DYNAMIC_MINORS) { |
684116ca EW |
200 | err = -EBUSY; |
201 | goto out; | |
1da177e4 | 202 | } |
1f2f38d8 TLSC |
203 | misc->minor = DYNAMIC_MINORS - i - 1; |
204 | set_bit(i, misc_minors); | |
3c94ce6f DK |
205 | } else { |
206 | struct miscdevice *c; | |
207 | ||
208 | list_for_each_entry(c, &misc_list, list) { | |
209 | if (c->minor == misc->minor) { | |
684116ca EW |
210 | err = -EBUSY; |
211 | goto out; | |
3c94ce6f DK |
212 | } |
213 | } | |
1da177e4 LT |
214 | } |
215 | ||
1da177e4 LT |
216 | dev = MKDEV(MISC_MAJOR, misc->minor); |
217 | ||
bd735995 TI |
218 | misc->this_device = |
219 | device_create_with_groups(misc_class, misc->parent, dev, | |
220 | misc, misc->groups, "%s", misc->name); | |
94fbcded | 221 | if (IS_ERR(misc->this_device)) { |
b575f712 VZ |
222 | if (is_dynamic) { |
223 | int i = DYNAMIC_MINORS - misc->minor - 1; | |
224 | ||
225 | if (i < DYNAMIC_MINORS && i >= 0) | |
226 | clear_bit(i, misc_minors); | |
227 | misc->minor = MISC_DYNAMIC_MINOR; | |
228 | } | |
94fbcded | 229 | err = PTR_ERR(misc->this_device); |
1da177e4 LT |
230 | goto out; |
231 | } | |
232 | ||
1da177e4 LT |
233 | /* |
234 | * Add it to the front, so that later devices can "override" | |
235 | * earlier defaults | |
236 | */ | |
237 | list_add(&misc->list, &misc_list); | |
238 | out: | |
0e82d5b6 | 239 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
240 | return err; |
241 | } | |
242 | ||
243 | /** | |
b844eba2 | 244 | * misc_deregister - unregister a miscellaneous device |
1da177e4 LT |
245 | * @misc: device to unregister |
246 | * | |
247 | * Unregister a miscellaneous device that was previously | |
f368ed60 | 248 | * successfully registered with misc_register(). |
1da177e4 LT |
249 | */ |
250 | ||
f368ed60 | 251 | void misc_deregister(struct miscdevice *misc) |
1da177e4 | 252 | { |
1f2f38d8 | 253 | int i = DYNAMIC_MINORS - misc->minor - 1; |
1da177e4 | 254 | |
b329becf | 255 | if (WARN_ON(list_empty(&misc->list))) |
f368ed60 | 256 | return; |
1da177e4 | 257 | |
0e82d5b6 | 258 | mutex_lock(&misc_mtx); |
1da177e4 | 259 | list_del(&misc->list); |
b844eba2 | 260 | device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); |
4ae717da | 261 | if (i < DYNAMIC_MINORS && i >= 0) |
1f2f38d8 | 262 | clear_bit(i, misc_minors); |
0e82d5b6 | 263 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
264 | } |
265 | ||
266 | EXPORT_SYMBOL(misc_register); | |
b844eba2 | 267 | EXPORT_SYMBOL(misc_deregister); |
1da177e4 | 268 | |
2c9ede55 | 269 | static char *misc_devnode(struct device *dev, umode_t *mode) |
d4056405 KS |
270 | { |
271 | struct miscdevice *c = dev_get_drvdata(dev); | |
272 | ||
e454cea2 KS |
273 | if (mode && c->mode) |
274 | *mode = c->mode; | |
275 | if (c->nodename) | |
276 | return kstrdup(c->nodename, GFP_KERNEL); | |
d4056405 KS |
277 | return NULL; |
278 | } | |
279 | ||
1da177e4 LT |
280 | static int __init misc_init(void) |
281 | { | |
1b502217 | 282 | int err; |
1037b278 | 283 | struct proc_dir_entry *ret; |
1da177e4 | 284 | |
1037b278 | 285 | ret = proc_create("misc", 0, NULL, &misc_proc_fops); |
ca8eca68 | 286 | misc_class = class_create(THIS_MODULE, "misc"); |
1b502217 | 287 | err = PTR_ERR(misc_class); |
1da177e4 | 288 | if (IS_ERR(misc_class)) |
1b502217 | 289 | goto fail_remove; |
573fc113 | 290 | |
1b502217 | 291 | err = -EIO; |
50a5e314 | 292 | if (register_chrdev(MISC_MAJOR, "misc", &misc_fops)) |
1b502217 | 293 | goto fail_printk; |
e454cea2 | 294 | misc_class->devnode = misc_devnode; |
1da177e4 | 295 | return 0; |
1b502217 DL |
296 | |
297 | fail_printk: | |
8ab44b40 | 298 | pr_err("unable to get major %d for misc devices\n", MISC_MAJOR); |
1b502217 DL |
299 | class_destroy(misc_class); |
300 | fail_remove: | |
1037b278 SM |
301 | if (ret) |
302 | remove_proc_entry("misc", NULL); | |
1b502217 | 303 | return err; |
1da177e4 LT |
304 | } |
305 | subsys_initcall(misc_init); |