1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/fs/char_dev.c |
4 | * |
5 | * Copyright (C) 1991, 1992 Linus Torvalds |
6 | */ |
7 | |
8 | #include <linux/init.h> |
9 | #include <linux/fs.h> |
10 | #include <linux/kdev_t.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/string.h> |
13 | |
14 | #include <linux/major.h> |
15 | #include <linux/errno.h> |
16 | #include <linux/module.h> |
17 | #include <linux/seq_file.h> |
18 | |
19 | #include <linux/kobject.h> |
20 | #include <linux/kobj_map.h> |
21 | #include <linux/cdev.h> |
22 | #include <linux/mutex.h> |
23 | #include <linux/backing-dev.h> |
24 | #include <linux/tty.h> |
25 | |
26 | #include "internal.h" |
27 | |
28 | static struct kobj_map *cdev_map __ro_after_init; |
29 | |
30 | static DEFINE_MUTEX(chrdevs_lock); |
31 | |
32 | #define CHRDEV_MAJOR_HASH_SIZE 255 |
33 | |
34 | static struct char_device_struct { |
35 | struct char_device_struct *next; |
36 | unsigned int major; |
37 | unsigned int baseminor; |
38 | int minorct; |
39 | char name[64]; |
40 | struct cdev *cdev; /* will die */ |
41 | } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; |
42 | |
43 | /* index in the above */ |
44 | static inline int major_to_index(unsigned major) |
45 | { |
46 | return major % CHRDEV_MAJOR_HASH_SIZE; |
47 | } |
48 | |
49 | #ifdef CONFIG_PROC_FS |
50 | |
51 | void chrdev_show(struct seq_file *f, off_t offset) |
52 | { |
53 | struct char_device_struct *cd; |
54 | |
55 | mutex_lock(&chrdevs_lock); |
56 | for (cd = chrdevs[major_to_index(major: offset)]; cd; cd = cd->next) { |
57 | if (cd->major == offset) |
58 | seq_printf(m: f, fmt: "%3d %s\n" , cd->major, cd->name); |
59 | } |
60 | mutex_unlock(lock: &chrdevs_lock); |
61 | } |
62 | |
63 | #endif /* CONFIG_PROC_FS */ |
64 | |
65 | static int find_dynamic_major(void) |
66 | { |
67 | int i; |
68 | struct char_device_struct *cd; |
69 | |
70 | for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) { |
71 | if (chrdevs[i] == NULL) |
72 | return i; |
73 | } |
74 | |
75 | for (i = CHRDEV_MAJOR_DYN_EXT_START; |
76 | i >= CHRDEV_MAJOR_DYN_EXT_END; i--) { |
77 | for (cd = chrdevs[major_to_index(major: i)]; cd; cd = cd->next) |
78 | if (cd->major == i) |
79 | break; |
80 | |
81 | if (cd == NULL) |
82 | return i; |
83 | } |
84 | |
85 | return -EBUSY; |
86 | } |
87 | |
88 | /* |
89 | * Register a single major with a specified minor range. |
90 | * |
91 | * If major == 0 this function will dynamically allocate an unused major. |
92 | * If major > 0 this function will attempt to reserve the range of minors |
93 | * with given major. |
94 | * |
95 | */ |
96 | static struct char_device_struct * |
97 | __register_chrdev_region(unsigned int major, unsigned int baseminor, |
98 | int minorct, const char *name) |
99 | { |
100 | struct char_device_struct *cd, *curr, *prev = NULL; |
101 | int ret; |
102 | int i; |
103 | |
104 | if (major >= CHRDEV_MAJOR_MAX) { |
105 | pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n" , |
106 | name, major, CHRDEV_MAJOR_MAX-1); |
107 | return ERR_PTR(error: -EINVAL); |
108 | } |
109 | |
110 | if (minorct > MINORMASK + 1 - baseminor) { |
111 | pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n" , |
112 | name, baseminor, baseminor + minorct - 1, 0, MINORMASK); |
113 | return ERR_PTR(error: -EINVAL); |
114 | } |
115 | |
116 | cd = kzalloc(size: sizeof(struct char_device_struct), GFP_KERNEL); |
117 | if (cd == NULL) |
118 | return ERR_PTR(error: -ENOMEM); |
119 | |
120 | mutex_lock(&chrdevs_lock); |
121 | |
122 | if (major == 0) { |
123 | ret = find_dynamic_major(); |
124 | if (ret < 0) { |
125 | pr_err("CHRDEV \"%s\" dynamic allocation region is full\n" , |
126 | name); |
127 | goto out; |
128 | } |
129 | major = ret; |
130 | } |
131 | |
132 | ret = -EBUSY; |
133 | i = major_to_index(major); |
134 | for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) { |
135 | if (curr->major < major) |
136 | continue; |
137 | |
138 | if (curr->major > major) |
139 | break; |
140 | |
141 | if (curr->baseminor + curr->minorct <= baseminor) |
142 | continue; |
143 | |
144 | if (curr->baseminor >= baseminor + minorct) |
145 | break; |
146 | |
147 | goto out; |
148 | } |
149 | |
150 | cd->major = major; |
151 | cd->baseminor = baseminor; |
152 | cd->minorct = minorct; |
153 | strscpy(p: cd->name, q: name, size: sizeof(cd->name)); |
154 | |
155 | if (!prev) { |
156 | cd->next = curr; |
157 | chrdevs[i] = cd; |
158 | } else { |
159 | cd->next = prev->next; |
160 | prev->next = cd; |
161 | } |
162 | |
163 | mutex_unlock(lock: &chrdevs_lock); |
164 | return cd; |
165 | out: |
166 | mutex_unlock(lock: &chrdevs_lock); |
167 | kfree(objp: cd); |
168 | return ERR_PTR(error: ret); |
169 | } |
170 | |
171 | static struct char_device_struct * |
172 | __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) |
173 | { |
174 | struct char_device_struct *cd = NULL, **cp; |
175 | int i = major_to_index(major); |
176 | |
177 | mutex_lock(&chrdevs_lock); |
178 | for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next) |
179 | if ((*cp)->major == major && |
180 | (*cp)->baseminor == baseminor && |
181 | (*cp)->minorct == minorct) |
182 | break; |
183 | if (*cp) { |
184 | cd = *cp; |
185 | *cp = cd->next; |
186 | } |
187 | mutex_unlock(lock: &chrdevs_lock); |
188 | return cd; |
189 | } |
190 | |
191 | /** |
192 | * register_chrdev_region() - register a range of device numbers |
193 | * @from: the first in the desired range of device numbers; must include |
194 | * the major number. |
195 | * @count: the number of consecutive device numbers required |
196 | * @name: the name of the device or driver. |
197 | * |
198 | * Return value is zero on success, a negative error code on failure. |
199 | */ |
200 | int register_chrdev_region(dev_t from, unsigned count, const char *name) |
201 | { |
202 | struct char_device_struct *cd; |
203 | dev_t to = from + count; |
204 | dev_t n, next; |
205 | |
206 | for (n = from; n < to; n = next) { |
207 | next = MKDEV(MAJOR(n)+1, 0); |
208 | if (next > to) |
209 | next = to; |
210 | cd = __register_chrdev_region(MAJOR(n), MINOR(n), |
211 | minorct: next - n, name); |
212 | if (IS_ERR(ptr: cd)) |
213 | goto fail; |
214 | } |
215 | return 0; |
216 | fail: |
217 | to = n; |
218 | for (n = from; n < to; n = next) { |
219 | next = MKDEV(MAJOR(n)+1, 0); |
220 | kfree(objp: __unregister_chrdev_region(MAJOR(n), MINOR(n), minorct: next - n)); |
221 | } |
222 | return PTR_ERR(ptr: cd); |
223 | } |
224 | |
225 | /** |
226 | * alloc_chrdev_region() - register a range of char device numbers |
227 | * @dev: output parameter for first assigned number |
228 | * @baseminor: first of the requested range of minor numbers |
229 | * @count: the number of minor numbers required |
230 | * @name: the name of the associated device or driver |
231 | * |
232 | * Allocates a range of char device numbers. The major number will be |
233 | * chosen dynamically, and returned (along with the first minor number) |
234 | * in @dev. Returns zero or a negative error code. |
235 | */ |
236 | int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, |
237 | const char *name) |
238 | { |
239 | struct char_device_struct *cd; |
240 | cd = __register_chrdev_region(major: 0, baseminor, minorct: count, name); |
241 | if (IS_ERR(ptr: cd)) |
242 | return PTR_ERR(ptr: cd); |
243 | *dev = MKDEV(cd->major, cd->baseminor); |
244 | return 0; |
245 | } |
246 | |
247 | /** |
248 | * __register_chrdev() - create and register a cdev occupying a range of minors |
249 | * @major: major device number or 0 for dynamic allocation |
250 | * @baseminor: first of the requested range of minor numbers |
251 | * @count: the number of minor numbers required |
252 | * @name: name of this range of devices |
253 | * @fops: file operations associated with this devices |
254 | * |
255 | * If @major == 0 this functions will dynamically allocate a major and return |
256 | * its number. |
257 | * |
258 | * If @major > 0 this function will attempt to reserve a device with the given |
259 | * major number and will return zero on success. |
260 | * |
261 | * Returns a -ve errno on failure. |
262 | * |
263 | * The name of this device has nothing to do with the name of the device in |
264 | * /dev. It only helps to keep track of the different owners of devices. If |
265 | * your module name has only one type of devices it's ok to use e.g. the name |
266 | * of the module here. |
267 | */ |
268 | int __register_chrdev(unsigned int major, unsigned int baseminor, |
269 | unsigned int count, const char *name, |
270 | const struct file_operations *fops) |
271 | { |
272 | struct char_device_struct *cd; |
273 | struct cdev *cdev; |
274 | int err = -ENOMEM; |
275 | |
276 | cd = __register_chrdev_region(major, baseminor, minorct: count, name); |
277 | if (IS_ERR(ptr: cd)) |
278 | return PTR_ERR(ptr: cd); |
279 | |
280 | cdev = cdev_alloc(); |
281 | if (!cdev) |
282 | goto out2; |
283 | |
284 | cdev->owner = fops->owner; |
285 | cdev->ops = fops; |
286 | kobject_set_name(kobj: &cdev->kobj, name: "%s" , name); |
287 | |
288 | err = cdev_add(cdev, MKDEV(cd->major, baseminor), count); |
289 | if (err) |
290 | goto out; |
291 | |
292 | cd->cdev = cdev; |
293 | |
294 | return major ? 0 : cd->major; |
295 | out: |
296 | kobject_put(kobj: &cdev->kobj); |
297 | out2: |
298 | kfree(objp: __unregister_chrdev_region(major: cd->major, baseminor, minorct: count)); |
299 | return err; |
300 | } |
301 | |
302 | /** |
303 | * unregister_chrdev_region() - unregister a range of device numbers |
304 | * @from: the first in the range of numbers to unregister |
305 | * @count: the number of device numbers to unregister |
306 | * |
307 | * This function will unregister a range of @count device numbers, |
308 | * starting with @from. The caller should normally be the one who |
309 | * allocated those numbers in the first place... |
310 | */ |
311 | void unregister_chrdev_region(dev_t from, unsigned count) |
312 | { |
313 | dev_t to = from + count; |
314 | dev_t n, next; |
315 | |
316 | for (n = from; n < to; n = next) { |
317 | next = MKDEV(MAJOR(n)+1, 0); |
318 | if (next > to) |
319 | next = to; |
320 | kfree(objp: __unregister_chrdev_region(MAJOR(n), MINOR(n), minorct: next - n)); |
321 | } |
322 | } |
323 | |
324 | /** |
325 | * __unregister_chrdev - unregister and destroy a cdev |
326 | * @major: major device number |
327 | * @baseminor: first of the range of minor numbers |
328 | * @count: the number of minor numbers this cdev is occupying |
329 | * @name: name of this range of devices |
330 | * |
331 | * Unregister and destroy the cdev occupying the region described by |
332 | * @major, @baseminor and @count. This function undoes what |
333 | * __register_chrdev() did. |
334 | */ |
335 | void __unregister_chrdev(unsigned int major, unsigned int baseminor, |
336 | unsigned int count, const char *name) |
337 | { |
338 | struct char_device_struct *cd; |
339 | |
340 | cd = __unregister_chrdev_region(major, baseminor, minorct: count); |
341 | if (cd && cd->cdev) |
342 | cdev_del(cd->cdev); |
343 | kfree(objp: cd); |
344 | } |
345 | |
346 | static DEFINE_SPINLOCK(cdev_lock); |
347 | |
348 | static struct kobject *cdev_get(struct cdev *p) |
349 | { |
350 | struct module *owner = p->owner; |
351 | struct kobject *kobj; |
352 | |
353 | if (!try_module_get(module: owner)) |
354 | return NULL; |
355 | kobj = kobject_get_unless_zero(kobj: &p->kobj); |
356 | if (!kobj) |
357 | module_put(module: owner); |
358 | return kobj; |
359 | } |
360 | |
361 | void cdev_put(struct cdev *p) |
362 | { |
363 | if (p) { |
364 | struct module *owner = p->owner; |
365 | kobject_put(kobj: &p->kobj); |
366 | module_put(module: owner); |
367 | } |
368 | } |
369 | |
370 | /* |
371 | * Called every time a character special file is opened |
372 | */ |
373 | static int chrdev_open(struct inode *inode, struct file *filp) |
374 | { |
375 | const struct file_operations *fops; |
376 | struct cdev *p; |
377 | struct cdev *new = NULL; |
378 | int ret = 0; |
379 | |
380 | spin_lock(lock: &cdev_lock); |
381 | p = inode->i_cdev; |
382 | if (!p) { |
383 | struct kobject *kobj; |
384 | int idx; |
385 | spin_unlock(lock: &cdev_lock); |
386 | kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); |
387 | if (!kobj) |
388 | return -ENXIO; |
389 | new = container_of(kobj, struct cdev, kobj); |
390 | spin_lock(lock: &cdev_lock); |
391 | /* Check i_cdev again in case somebody beat us to it while |
392 | we dropped the lock. */ |
393 | p = inode->i_cdev; |
394 | if (!p) { |
395 | inode->i_cdev = p = new; |
396 | list_add(new: &inode->i_devices, head: &p->list); |
397 | new = NULL; |
398 | } else if (!cdev_get(p)) |
399 | ret = -ENXIO; |
400 | } else if (!cdev_get(p)) |
401 | ret = -ENXIO; |
402 | spin_unlock(lock: &cdev_lock); |
403 | cdev_put(p: new); |
404 | if (ret) |
405 | return ret; |
406 | |
407 | ret = -ENXIO; |
408 | fops = fops_get(p->ops); |
409 | if (!fops) |
410 | goto out_cdev_put; |
411 | |
412 | replace_fops(filp, fops); |
413 | if (filp->f_op->open) { |
414 | ret = filp->f_op->open(inode, filp); |
415 | if (ret) |
416 | goto out_cdev_put; |
417 | } |
418 | |
419 | return 0; |
420 | |
421 | out_cdev_put: |
422 | cdev_put(p); |
423 | return ret; |
424 | } |
425 | |
426 | void cd_forget(struct inode *inode) |
427 | { |
428 | spin_lock(lock: &cdev_lock); |
429 | list_del_init(entry: &inode->i_devices); |
430 | inode->i_cdev = NULL; |
431 | inode->i_mapping = &inode->i_data; |
432 | spin_unlock(lock: &cdev_lock); |
433 | } |
434 | |
435 | static void cdev_purge(struct cdev *cdev) |
436 | { |
437 | spin_lock(lock: &cdev_lock); |
438 | while (!list_empty(head: &cdev->list)) { |
439 | struct inode *inode; |
440 | inode = container_of(cdev->list.next, struct inode, i_devices); |
441 | list_del_init(entry: &inode->i_devices); |
442 | inode->i_cdev = NULL; |
443 | } |
444 | spin_unlock(lock: &cdev_lock); |
445 | } |
446 | |
447 | /* |
448 | * Dummy default file-operations: the only thing this does |
449 | * is contain the open that then fills in the correct operations |
450 | * depending on the special file... |
451 | */ |
452 | const struct file_operations def_chr_fops = { |
453 | .open = chrdev_open, |
454 | .llseek = noop_llseek, |
455 | }; |
456 | |
457 | static struct kobject *exact_match(dev_t dev, int *part, void *data) |
458 | { |
459 | struct cdev *p = data; |
460 | return &p->kobj; |
461 | } |
462 | |
463 | static int exact_lock(dev_t dev, void *data) |
464 | { |
465 | struct cdev *p = data; |
466 | return cdev_get(p) ? 0 : -1; |
467 | } |
468 | |
469 | /** |
470 | * cdev_add() - add a char device to the system |
471 | * @p: the cdev structure for the device |
472 | * @dev: the first device number for which this device is responsible |
473 | * @count: the number of consecutive minor numbers corresponding to this |
474 | * device |
475 | * |
476 | * cdev_add() adds the device represented by @p to the system, making it |
477 | * live immediately. A negative error code is returned on failure. |
478 | */ |
479 | int cdev_add(struct cdev *p, dev_t dev, unsigned count) |
480 | { |
481 | int error; |
482 | |
483 | p->dev = dev; |
484 | p->count = count; |
485 | |
486 | if (WARN_ON(dev == WHITEOUT_DEV)) { |
487 | error = -EBUSY; |
488 | goto err; |
489 | } |
490 | |
491 | error = kobj_map(cdev_map, dev, count, NULL, |
492 | exact_match, exact_lock, p); |
493 | if (error) |
494 | goto err; |
495 | |
496 | kobject_get(kobj: p->kobj.parent); |
497 | |
498 | return 0; |
499 | |
500 | err: |
501 | kfree_const(x: p->kobj.name); |
502 | p->kobj.name = NULL; |
503 | return error; |
504 | } |
505 | |
506 | /** |
507 | * cdev_set_parent() - set the parent kobject for a char device |
508 | * @p: the cdev structure |
509 | * @kobj: the kobject to take a reference to |
510 | * |
511 | * cdev_set_parent() sets a parent kobject which will be referenced |
512 | * appropriately so the parent is not freed before the cdev. This |
513 | * should be called before cdev_add. |
514 | */ |
515 | void cdev_set_parent(struct cdev *p, struct kobject *kobj) |
516 | { |
517 | WARN_ON(!kobj->state_initialized); |
518 | p->kobj.parent = kobj; |
519 | } |
520 | |
521 | /** |
522 | * cdev_device_add() - add a char device and it's corresponding |
523 | * struct device, linkink |
524 | * @dev: the device structure |
525 | * @cdev: the cdev structure |
526 | * |
527 | * cdev_device_add() adds the char device represented by @cdev to the system, |
528 | * just as cdev_add does. It then adds @dev to the system using device_add |
529 | * The dev_t for the char device will be taken from the struct device which |
530 | * needs to be initialized first. This helper function correctly takes a |
531 | * reference to the parent device so the parent will not get released until |
532 | * all references to the cdev are released. |
533 | * |
534 | * This helper uses dev->devt for the device number. If it is not set |
535 | * it will not add the cdev and it will be equivalent to device_add. |
536 | * |
537 | * This function should be used whenever the struct cdev and the |
538 | * struct device are members of the same structure whose lifetime is |
539 | * managed by the struct device. |
540 | * |
541 | * NOTE: Callers must assume that userspace was able to open the cdev and |
542 | * can call cdev fops callbacks at any time, even if this function fails. |
543 | */ |
544 | int cdev_device_add(struct cdev *cdev, struct device *dev) |
545 | { |
546 | int rc = 0; |
547 | |
548 | if (dev->devt) { |
549 | cdev_set_parent(p: cdev, kobj: &dev->kobj); |
550 | |
551 | rc = cdev_add(p: cdev, dev: dev->devt, count: 1); |
552 | if (rc) |
553 | return rc; |
554 | } |
555 | |
556 | rc = device_add(dev); |
557 | if (rc && dev->devt) |
558 | cdev_del(cdev); |
559 | |
560 | return rc; |
561 | } |
562 | |
563 | /** |
564 | * cdev_device_del() - inverse of cdev_device_add |
565 | * @dev: the device structure |
566 | * @cdev: the cdev structure |
567 | * |
568 | * cdev_device_del() is a helper function to call cdev_del and device_del. |
569 | * It should be used whenever cdev_device_add is used. |
570 | * |
571 | * If dev->devt is not set it will not remove the cdev and will be equivalent |
572 | * to device_del. |
573 | * |
574 | * NOTE: This guarantees that associated sysfs callbacks are not running |
575 | * or runnable, however any cdevs already open will remain and their fops |
576 | * will still be callable even after this function returns. |
577 | */ |
578 | void cdev_device_del(struct cdev *cdev, struct device *dev) |
579 | { |
580 | device_del(dev); |
581 | if (dev->devt) |
582 | cdev_del(cdev); |
583 | } |
584 | |
585 | static void cdev_unmap(dev_t dev, unsigned count) |
586 | { |
587 | kobj_unmap(cdev_map, dev, count); |
588 | } |
589 | |
590 | /** |
591 | * cdev_del() - remove a cdev from the system |
592 | * @p: the cdev structure to be removed |
593 | * |
594 | * cdev_del() removes @p from the system, possibly freeing the structure |
595 | * itself. |
596 | * |
597 | * NOTE: This guarantees that cdev device will no longer be able to be |
598 | * opened, however any cdevs already open will remain and their fops will |
599 | * still be callable even after cdev_del returns. |
600 | */ |
601 | void cdev_del(struct cdev *p) |
602 | { |
603 | cdev_unmap(dev: p->dev, count: p->count); |
604 | kobject_put(kobj: &p->kobj); |
605 | } |
606 | |
607 | |
608 | static void cdev_default_release(struct kobject *kobj) |
609 | { |
610 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
611 | struct kobject *parent = kobj->parent; |
612 | |
613 | cdev_purge(cdev: p); |
614 | kobject_put(kobj: parent); |
615 | } |
616 | |
617 | static void cdev_dynamic_release(struct kobject *kobj) |
618 | { |
619 | struct cdev *p = container_of(kobj, struct cdev, kobj); |
620 | struct kobject *parent = kobj->parent; |
621 | |
622 | cdev_purge(cdev: p); |
623 | kfree(objp: p); |
624 | kobject_put(kobj: parent); |
625 | } |
626 | |
627 | static struct kobj_type ktype_cdev_default = { |
628 | .release = cdev_default_release, |
629 | }; |
630 | |
631 | static struct kobj_type ktype_cdev_dynamic = { |
632 | .release = cdev_dynamic_release, |
633 | }; |
634 | |
635 | /** |
636 | * cdev_alloc() - allocate a cdev structure |
637 | * |
638 | * Allocates and returns a cdev structure, or NULL on failure. |
639 | */ |
640 | struct cdev *cdev_alloc(void) |
641 | { |
642 | struct cdev *p = kzalloc(size: sizeof(struct cdev), GFP_KERNEL); |
643 | if (p) { |
644 | INIT_LIST_HEAD(list: &p->list); |
645 | kobject_init(kobj: &p->kobj, ktype: &ktype_cdev_dynamic); |
646 | } |
647 | return p; |
648 | } |
649 | |
650 | /** |
651 | * cdev_init() - initialize a cdev structure |
652 | * @cdev: the structure to initialize |
653 | * @fops: the file_operations for this device |
654 | * |
655 | * Initializes @cdev, remembering @fops, making it ready to add to the |
656 | * system with cdev_add(). |
657 | */ |
658 | void cdev_init(struct cdev *cdev, const struct file_operations *fops) |
659 | { |
660 | memset(cdev, 0, sizeof *cdev); |
661 | INIT_LIST_HEAD(list: &cdev->list); |
662 | kobject_init(kobj: &cdev->kobj, ktype: &ktype_cdev_default); |
663 | cdev->ops = fops; |
664 | } |
665 | |
666 | static struct kobject *base_probe(dev_t dev, int *part, void *data) |
667 | { |
668 | if (request_module("char-major-%d-%d" , MAJOR(dev), MINOR(dev)) > 0) |
669 | /* Make old-style 2.4 aliases work */ |
670 | request_module("char-major-%d" , MAJOR(dev)); |
671 | return NULL; |
672 | } |
673 | |
674 | void __init chrdev_init(void) |
675 | { |
676 | cdev_map = kobj_map_init(base_probe, &chrdevs_lock); |
677 | } |
678 | |
679 | |
680 | /* Let modules do char dev stuff */ |
681 | EXPORT_SYMBOL(register_chrdev_region); |
682 | EXPORT_SYMBOL(unregister_chrdev_region); |
683 | EXPORT_SYMBOL(alloc_chrdev_region); |
684 | EXPORT_SYMBOL(cdev_init); |
685 | EXPORT_SYMBOL(cdev_alloc); |
686 | EXPORT_SYMBOL(cdev_del); |
687 | EXPORT_SYMBOL(cdev_add); |
688 | EXPORT_SYMBOL(cdev_set_parent); |
689 | EXPORT_SYMBOL(cdev_device_add); |
690 | EXPORT_SYMBOL(cdev_device_del); |
691 | EXPORT_SYMBOL(__register_chrdev); |
692 | EXPORT_SYMBOL(__unregister_chrdev); |
693 | |