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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 | }; | |
1da177e4 LT |
98 | #endif |
99 | ||
65ebd3df | 100 | static int misc_open(struct inode *inode, struct file *file) |
1da177e4 LT |
101 | { |
102 | int minor = iminor(inode); | |
103 | struct miscdevice *c; | |
104 | int err = -ENODEV; | |
e84f9e57 | 105 | const struct file_operations *new_fops = NULL; |
40b798ef | 106 | |
0e82d5b6 | 107 | mutex_lock(&misc_mtx); |
898bc282 | 108 | |
1da177e4 LT |
109 | list_for_each_entry(c, &misc_list, list) { |
110 | if (c->minor == minor) { | |
898bc282 | 111 | new_fops = fops_get(c->fops); |
1da177e4 LT |
112 | break; |
113 | } | |
114 | } | |
898bc282 | 115 | |
1da177e4 | 116 | if (!new_fops) { |
0e82d5b6 | 117 | mutex_unlock(&misc_mtx); |
1da177e4 | 118 | request_module("char-major-%d-%d", MISC_MAJOR, minor); |
0e82d5b6 | 119 | mutex_lock(&misc_mtx); |
1da177e4 LT |
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 | if (!new_fops) | |
128 | goto fail; | |
129 | } | |
130 | ||
0b509d8d TVB |
131 | /* |
132 | * Place the miscdevice in the file's | |
133 | * private_data so it can be used by the | |
134 | * file operations, including f_op->open below | |
135 | */ | |
136 | file->private_data = c; | |
137 | ||
1da177e4 | 138 | err = 0; |
e84f9e57 | 139 | replace_fops(file, new_fops); |
0b509d8d | 140 | if (file->f_op->open) |
50a5e314 | 141 | err = file->f_op->open(inode, file); |
1da177e4 | 142 | fail: |
0e82d5b6 | 143 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
144 | return err; |
145 | } | |
146 | ||
ca8eca68 | 147 | static struct class *misc_class; |
1da177e4 | 148 | |
62322d25 | 149 | static const struct file_operations misc_fops = { |
1da177e4 LT |
150 | .owner = THIS_MODULE, |
151 | .open = misc_open, | |
6038f373 | 152 | .llseek = noop_llseek, |
1da177e4 LT |
153 | }; |
154 | ||
1da177e4 LT |
155 | /** |
156 | * misc_register - register a miscellaneous device | |
157 | * @misc: device structure | |
898bc282 | 158 | * |
1da177e4 LT |
159 | * Register a miscellaneous device with the kernel. If the minor |
160 | * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned | |
161 | * and placed in the minor field of the structure. For other cases | |
162 | * the minor number requested is used. | |
163 | * | |
164 | * The structure passed is linked into the kernel and may not be | |
03190c67 MK |
165 | * destroyed until it has been unregistered. By default, an open() |
166 | * syscall to the device sets file->private_data to point to the | |
167 | * structure. Drivers don't need open in fops for this. | |
1da177e4 LT |
168 | * |
169 | * A zero is returned on success and a negative errno code for | |
170 | * failure. | |
171 | */ | |
898bc282 | 172 | |
65ebd3df | 173 | int misc_register(struct miscdevice *misc) |
1da177e4 | 174 | { |
1da177e4 | 175 | dev_t dev; |
7c69ef79 | 176 | int err = 0; |
b575f712 | 177 | bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR); |
1da177e4 | 178 | |
5d469ec0 NH |
179 | INIT_LIST_HEAD(&misc->list); |
180 | ||
0e82d5b6 | 181 | mutex_lock(&misc_mtx); |
1da177e4 | 182 | |
b575f712 | 183 | if (is_dynamic) { |
1f2f38d8 | 184 | int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS); |
5b884a95 | 185 | |
1f2f38d8 | 186 | if (i >= DYNAMIC_MINORS) { |
684116ca EW |
187 | err = -EBUSY; |
188 | goto out; | |
1da177e4 | 189 | } |
1f2f38d8 TLSC |
190 | misc->minor = DYNAMIC_MINORS - i - 1; |
191 | set_bit(i, misc_minors); | |
3c94ce6f DK |
192 | } else { |
193 | struct miscdevice *c; | |
194 | ||
195 | list_for_each_entry(c, &misc_list, list) { | |
196 | if (c->minor == misc->minor) { | |
684116ca EW |
197 | err = -EBUSY; |
198 | goto out; | |
3c94ce6f DK |
199 | } |
200 | } | |
1da177e4 LT |
201 | } |
202 | ||
1da177e4 LT |
203 | dev = MKDEV(MISC_MAJOR, misc->minor); |
204 | ||
bd735995 TI |
205 | misc->this_device = |
206 | device_create_with_groups(misc_class, misc->parent, dev, | |
207 | misc, misc->groups, "%s", misc->name); | |
94fbcded | 208 | if (IS_ERR(misc->this_device)) { |
b575f712 VZ |
209 | if (is_dynamic) { |
210 | int i = DYNAMIC_MINORS - misc->minor - 1; | |
211 | ||
212 | if (i < DYNAMIC_MINORS && i >= 0) | |
213 | clear_bit(i, misc_minors); | |
214 | misc->minor = MISC_DYNAMIC_MINOR; | |
215 | } | |
94fbcded | 216 | err = PTR_ERR(misc->this_device); |
1da177e4 LT |
217 | goto out; |
218 | } | |
219 | ||
1da177e4 LT |
220 | /* |
221 | * Add it to the front, so that later devices can "override" | |
222 | * earlier defaults | |
223 | */ | |
224 | list_add(&misc->list, &misc_list); | |
225 | out: | |
0e82d5b6 | 226 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
227 | return err; |
228 | } | |
e89bec3a | 229 | EXPORT_SYMBOL(misc_register); |
1da177e4 LT |
230 | |
231 | /** | |
b844eba2 | 232 | * misc_deregister - unregister a miscellaneous device |
1da177e4 LT |
233 | * @misc: device to unregister |
234 | * | |
235 | * Unregister a miscellaneous device that was previously | |
f368ed60 | 236 | * successfully registered with misc_register(). |
1da177e4 LT |
237 | */ |
238 | ||
f368ed60 | 239 | void misc_deregister(struct miscdevice *misc) |
1da177e4 | 240 | { |
1f2f38d8 | 241 | int i = DYNAMIC_MINORS - misc->minor - 1; |
1da177e4 | 242 | |
b329becf | 243 | if (WARN_ON(list_empty(&misc->list))) |
f368ed60 | 244 | return; |
1da177e4 | 245 | |
0e82d5b6 | 246 | mutex_lock(&misc_mtx); |
1da177e4 | 247 | list_del(&misc->list); |
b844eba2 | 248 | device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); |
4ae717da | 249 | if (i < DYNAMIC_MINORS && i >= 0) |
1f2f38d8 | 250 | clear_bit(i, misc_minors); |
0e82d5b6 | 251 | mutex_unlock(&misc_mtx); |
1da177e4 | 252 | } |
b844eba2 | 253 | EXPORT_SYMBOL(misc_deregister); |
1da177e4 | 254 | |
2c9ede55 | 255 | static char *misc_devnode(struct device *dev, umode_t *mode) |
d4056405 KS |
256 | { |
257 | struct miscdevice *c = dev_get_drvdata(dev); | |
258 | ||
e454cea2 KS |
259 | if (mode && c->mode) |
260 | *mode = c->mode; | |
261 | if (c->nodename) | |
262 | return kstrdup(c->nodename, GFP_KERNEL); | |
d4056405 KS |
263 | return NULL; |
264 | } | |
265 | ||
1da177e4 LT |
266 | static int __init misc_init(void) |
267 | { | |
1b502217 | 268 | int err; |
1037b278 | 269 | struct proc_dir_entry *ret; |
1da177e4 | 270 | |
fddda2b7 | 271 | ret = proc_create_seq("misc", 0, NULL, &misc_seq_ops); |
ca8eca68 | 272 | misc_class = class_create(THIS_MODULE, "misc"); |
1b502217 | 273 | err = PTR_ERR(misc_class); |
1da177e4 | 274 | if (IS_ERR(misc_class)) |
1b502217 | 275 | goto fail_remove; |
573fc113 | 276 | |
1b502217 | 277 | err = -EIO; |
50a5e314 | 278 | if (register_chrdev(MISC_MAJOR, "misc", &misc_fops)) |
1b502217 | 279 | goto fail_printk; |
e454cea2 | 280 | misc_class->devnode = misc_devnode; |
1da177e4 | 281 | return 0; |
1b502217 DL |
282 | |
283 | fail_printk: | |
8ab44b40 | 284 | pr_err("unable to get major %d for misc devices\n", MISC_MAJOR); |
1b502217 DL |
285 | class_destroy(misc_class); |
286 | fail_remove: | |
1037b278 SM |
287 | if (ret) |
288 | remove_proc_entry("misc", NULL); | |
1b502217 | 289 | return err; |
1da177e4 LT |
290 | } |
291 | subsys_initcall(misc_init); |