blob: f80a4f25123c3fa912daa1eb4080e69dab3d58fb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/char_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/init.h>
8#include <linux/fs.h>
Andrew Mortonb446b602007-02-20 13:57:48 -08009#include <linux/kdev_t.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/slab.h>
11#include <linux/string.h>
12
13#include <linux/major.h>
14#include <linux/errno.h>
15#include <linux/module.h>
Joe Korty68eef3b2006-03-31 02:30:32 -080016#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
18#include <linux/kobject.h>
19#include <linux/kobj_map.h>
20#include <linux/cdev.h>
Jes Sorensen58383af2006-02-06 14:12:43 -080021#include <linux/mutex.h>
David Howells5da61852006-09-27 01:50:16 -070022#include <linux/backing-dev.h>
David Howells31d1d482010-08-06 16:34:43 +010023#include <linux/tty.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
David Howells07f3f05c2006-09-30 20:52:18 +020025#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
David Howells5da61852006-09-27 01:50:16 -070027/*
28 * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
29 * devices
30 * - permits shared-mmap for read, write and/or exec
31 * - does not permit private mmap in NOMMU mode (can't do COW)
32 * - no readahead or I/O queue unplugging required
33 */
34struct backing_dev_info directly_mappable_cdev_bdi = {
Jens Axboed9938312009-06-12 14:45:52 +020035 .name = "char",
David Howells5da61852006-09-27 01:50:16 -070036 .capabilities = (
37#ifdef CONFIG_MMU
38 /* permit private copies of the data to be taken */
39 BDI_CAP_MAP_COPY |
40#endif
41 /* permit direct mmap, for read, write or exec */
42 BDI_CAP_MAP_DIRECT |
43 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
44};
45
Linus Torvalds1da177e2005-04-16 15:20:36 -070046static struct kobj_map *cdev_map;
47
Jes Sorensen58383af2006-02-06 14:12:43 -080048static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50static struct char_device_struct {
51 struct char_device_struct *next;
52 unsigned int major;
53 unsigned int baseminor;
54 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080055 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080057} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59/* index in the above */
60static inline int major_to_index(int major)
61{
Joe Korty68eef3b2006-03-31 02:30:32 -080062 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063}
64
Joe Korty68eef3b2006-03-31 02:30:32 -080065#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080066
Joe Korty68eef3b2006-03-31 02:30:32 -080067void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070068{
69 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
Joe Korty68eef3b2006-03-31 02:30:32 -080071 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
72 mutex_lock(&chrdevs_lock);
73 for (cd = chrdevs[offset]; cd; cd = cd->next)
74 seq_printf(f, "%3d %s\n", cd->major, cd->name);
75 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 }
Neil Horman7170be52006-01-14 13:20:38 -080077}
78
Joe Korty68eef3b2006-03-31 02:30:32 -080079#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
81/*
82 * Register a single major with a specified minor range.
83 *
84 * If major == 0 this functions will dynamically allocate a major and return
85 * its number.
86 *
87 * If major > 0 this function will attempt to reserve the passed range of
88 * minors and will return zero on success.
89 *
90 * Returns a -ve errno on failure.
91 */
92static struct char_device_struct *
93__register_chrdev_region(unsigned int major, unsigned int baseminor,
94 int minorct, const char *name)
95{
96 struct char_device_struct *cd, **cp;
97 int ret = 0;
98 int i;
99
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800100 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 if (cd == NULL)
102 return ERR_PTR(-ENOMEM);
103
Jes Sorensen58383af2006-02-06 14:12:43 -0800104 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
106 /* temporary */
107 if (major == 0) {
108 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
109 if (chrdevs[i] == NULL)
110 break;
111 }
112
113 if (i == 0) {
114 ret = -EBUSY;
115 goto out;
116 }
117 major = i;
118 ret = major;
119 }
120
121 cd->major = major;
122 cd->baseminor = baseminor;
123 cd->minorct = minorct;
Cyrill Gorcunov8c4018882009-01-06 14:41:08 -0800124 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125
126 i = major_to_index(major);
127
128 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
129 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700130 ((*cp)->major == major &&
131 (((*cp)->baseminor >= baseminor) ||
132 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700134
135 /* Check for overlapping minor ranges. */
136 if (*cp && (*cp)->major == major) {
137 int old_min = (*cp)->baseminor;
138 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
139 int new_min = baseminor;
140 int new_max = baseminor + minorct - 1;
141
142 /* New driver overlaps from the left. */
143 if (new_max >= old_min && new_max <= old_max) {
144 ret = -EBUSY;
145 goto out;
146 }
147
148 /* New driver overlaps from the right. */
149 if (new_min <= old_max && new_min >= old_min) {
150 ret = -EBUSY;
151 goto out;
152 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 cd->next = *cp;
156 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800157 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 return cd;
159out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800160 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 kfree(cd);
162 return ERR_PTR(ret);
163}
164
165static struct char_device_struct *
166__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
167{
168 struct char_device_struct *cd = NULL, **cp;
169 int i = major_to_index(major);
170
Jes Sorensen58383af2006-02-06 14:12:43 -0800171 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
173 if ((*cp)->major == major &&
174 (*cp)->baseminor == baseminor &&
175 (*cp)->minorct == minorct)
176 break;
177 if (*cp) {
178 cd = *cp;
179 *cp = cd->next;
180 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800181 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 return cd;
183}
184
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700185/**
186 * register_chrdev_region() - register a range of device numbers
187 * @from: the first in the desired range of device numbers; must include
188 * the major number.
189 * @count: the number of consecutive device numbers required
190 * @name: the name of the device or driver.
191 *
192 * Return value is zero on success, a negative error code on failure.
193 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194int register_chrdev_region(dev_t from, unsigned count, const char *name)
195{
196 struct char_device_struct *cd;
197 dev_t to = from + count;
198 dev_t n, next;
199
200 for (n = from; n < to; n = next) {
201 next = MKDEV(MAJOR(n)+1, 0);
202 if (next > to)
203 next = to;
204 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
205 next - n, name);
206 if (IS_ERR(cd))
207 goto fail;
208 }
209 return 0;
210fail:
211 to = n;
212 for (n = from; n < to; n = next) {
213 next = MKDEV(MAJOR(n)+1, 0);
214 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
215 }
216 return PTR_ERR(cd);
217}
218
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700219/**
220 * alloc_chrdev_region() - register a range of char device numbers
221 * @dev: output parameter for first assigned number
222 * @baseminor: first of the requested range of minor numbers
223 * @count: the number of minor numbers required
224 * @name: the name of the associated device or driver
225 *
226 * Allocates a range of char device numbers. The major number will be
227 * chosen dynamically, and returned (along with the first minor number)
228 * in @dev. Returns zero or a negative error code.
229 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
231 const char *name)
232{
233 struct char_device_struct *cd;
234 cd = __register_chrdev_region(0, baseminor, count, name);
235 if (IS_ERR(cd))
236 return PTR_ERR(cd);
237 *dev = MKDEV(cd->major, cd->baseminor);
238 return 0;
239}
240
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700241/**
Tejun Heo1905b1b2009-08-06 18:13:23 +0900242 * __register_chrdev() - create and register a cdev occupying a range of minors
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700243 * @major: major device number or 0 for dynamic allocation
Tejun Heo1905b1b2009-08-06 18:13:23 +0900244 * @baseminor: first of the requested range of minor numbers
245 * @count: the number of minor numbers required
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700246 * @name: name of this range of devices
247 * @fops: file operations associated with this devices
248 *
249 * If @major == 0 this functions will dynamically allocate a major and return
250 * its number.
251 *
252 * If @major > 0 this function will attempt to reserve a device with the given
253 * major number and will return zero on success.
254 *
255 * Returns a -ve errno on failure.
256 *
257 * The name of this device has nothing to do with the name of the device in
258 * /dev. It only helps to keep track of the different owners of devices. If
259 * your module name has only one type of devices it's ok to use e.g. the name
260 * of the module here.
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700261 */
Tejun Heo1905b1b2009-08-06 18:13:23 +0900262int __register_chrdev(unsigned int major, unsigned int baseminor,
263 unsigned int count, const char *name,
264 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265{
266 struct char_device_struct *cd;
267 struct cdev *cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 int err = -ENOMEM;
269
Tejun Heo1905b1b2009-08-06 18:13:23 +0900270 cd = __register_chrdev_region(major, baseminor, count, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 if (IS_ERR(cd))
272 return PTR_ERR(cd);
273
274 cdev = cdev_alloc();
275 if (!cdev)
276 goto out2;
277
278 cdev->owner = fops->owner;
279 cdev->ops = fops;
280 kobject_set_name(&cdev->kobj, "%s", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
Tejun Heo1905b1b2009-08-06 18:13:23 +0900282 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 if (err)
284 goto out;
285
286 cd->cdev = cdev;
287
288 return major ? 0 : cd->major;
289out:
290 kobject_put(&cdev->kobj);
291out2:
Tejun Heo1905b1b2009-08-06 18:13:23 +0900292 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 return err;
294}
295
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700296/**
297 * unregister_chrdev_region() - return a range of device numbers
298 * @from: the first in the range of numbers to unregister
299 * @count: the number of device numbers to unregister
300 *
301 * This function will unregister a range of @count device numbers,
302 * starting with @from. The caller should normally be the one who
303 * allocated those numbers in the first place...
304 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305void unregister_chrdev_region(dev_t from, unsigned count)
306{
307 dev_t to = from + count;
308 dev_t n, next;
309
310 for (n = from; n < to; n = next) {
311 next = MKDEV(MAJOR(n)+1, 0);
312 if (next > to)
313 next = to;
314 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
315 }
316}
317
Tejun Heo1905b1b2009-08-06 18:13:23 +0900318/**
319 * __unregister_chrdev - unregister and destroy a cdev
320 * @major: major device number
321 * @baseminor: first of the range of minor numbers
322 * @count: the number of minor numbers this cdev is occupying
323 * @name: name of this range of devices
324 *
325 * Unregister and destroy the cdev occupying the region described by
326 * @major, @baseminor and @count. This function undoes what
327 * __register_chrdev() did.
328 */
329void __unregister_chrdev(unsigned int major, unsigned int baseminor,
330 unsigned int count, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331{
332 struct char_device_struct *cd;
Tejun Heo1905b1b2009-08-06 18:13:23 +0900333
334 cd = __unregister_chrdev_region(major, baseminor, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 if (cd && cd->cdev)
336 cdev_del(cd->cdev);
337 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338}
339
340static DEFINE_SPINLOCK(cdev_lock);
341
342static struct kobject *cdev_get(struct cdev *p)
343{
344 struct module *owner = p->owner;
345 struct kobject *kobj;
346
347 if (owner && !try_module_get(owner))
348 return NULL;
349 kobj = kobject_get(&p->kobj);
350 if (!kobj)
351 module_put(owner);
352 return kobj;
353}
354
355void cdev_put(struct cdev *p)
356{
357 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700358 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700360 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 }
362}
363
364/*
365 * Called every time a character special file is opened
366 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800367static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368{
369 struct cdev *p;
370 struct cdev *new = NULL;
371 int ret = 0;
372
373 spin_lock(&cdev_lock);
374 p = inode->i_cdev;
375 if (!p) {
376 struct kobject *kobj;
377 int idx;
378 spin_unlock(&cdev_lock);
379 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
380 if (!kobj)
381 return -ENXIO;
382 new = container_of(kobj, struct cdev, kobj);
383 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600384 /* Check i_cdev again in case somebody beat us to it while
385 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 p = inode->i_cdev;
387 if (!p) {
388 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 list_add(&inode->i_devices, &p->list);
390 new = NULL;
391 } else if (!cdev_get(p))
392 ret = -ENXIO;
393 } else if (!cdev_get(p))
394 ret = -ENXIO;
395 spin_unlock(&cdev_lock);
396 cdev_put(new);
397 if (ret)
398 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200399
400 ret = -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 filp->f_op = fops_get(p->ops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200402 if (!filp->f_op)
403 goto out_cdev_put;
404
405 if (filp->f_op->open) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 ret = filp->f_op->open(inode,filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200407 if (ret)
408 goto out_cdev_put;
409 }
410
411 return 0;
412
413 out_cdev_put:
414 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 return ret;
416}
417
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400418int cdev_index(struct inode *inode)
419{
420 int idx;
421 struct kobject *kobj;
422
423 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
424 if (!kobj)
425 return -1;
426 kobject_put(kobj);
427 return idx;
428}
429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430void cd_forget(struct inode *inode)
431{
432 spin_lock(&cdev_lock);
433 list_del_init(&inode->i_devices);
434 inode->i_cdev = NULL;
435 spin_unlock(&cdev_lock);
436}
437
Adrian Bunk75c96f82005-05-05 16:16:09 -0700438static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439{
440 spin_lock(&cdev_lock);
441 while (!list_empty(&cdev->list)) {
442 struct inode *inode;
443 inode = container_of(cdev->list.next, struct inode, i_devices);
444 list_del_init(&inode->i_devices);
445 inode->i_cdev = NULL;
446 }
447 spin_unlock(&cdev_lock);
448}
449
450/*
451 * Dummy default file-operations: the only thing this does
452 * is contain the open that then fills in the correct operations
453 * depending on the special file...
454 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800455const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 .open = chrdev_open,
457};
458
459static struct kobject *exact_match(dev_t dev, int *part, void *data)
460{
461 struct cdev *p = data;
462 return &p->kobj;
463}
464
465static int exact_lock(dev_t dev, void *data)
466{
467 struct cdev *p = data;
468 return cdev_get(p) ? 0 : -1;
469}
470
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700471/**
472 * cdev_add() - add a char device to the system
473 * @p: the cdev structure for the device
474 * @dev: the first device number for which this device is responsible
475 * @count: the number of consecutive minor numbers corresponding to this
476 * device
477 *
478 * cdev_add() adds the device represented by @p to the system, making it
479 * live immediately. A negative error code is returned on failure.
480 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481int cdev_add(struct cdev *p, dev_t dev, unsigned count)
482{
483 p->dev = dev;
484 p->count = count;
485 return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
486}
487
488static void cdev_unmap(dev_t dev, unsigned count)
489{
490 kobj_unmap(cdev_map, dev, count);
491}
492
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700493/**
494 * cdev_del() - remove a cdev from the system
495 * @p: the cdev structure to be removed
496 *
497 * cdev_del() removes @p from the system, possibly freeing the structure
498 * itself.
499 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500void cdev_del(struct cdev *p)
501{
502 cdev_unmap(p->dev, p->count);
503 kobject_put(&p->kobj);
504}
505
506
507static void cdev_default_release(struct kobject *kobj)
508{
509 struct cdev *p = container_of(kobj, struct cdev, kobj);
510 cdev_purge(p);
511}
512
513static void cdev_dynamic_release(struct kobject *kobj)
514{
515 struct cdev *p = container_of(kobj, struct cdev, kobj);
516 cdev_purge(p);
517 kfree(p);
518}
519
520static struct kobj_type ktype_cdev_default = {
521 .release = cdev_default_release,
522};
523
524static struct kobj_type ktype_cdev_dynamic = {
525 .release = cdev_dynamic_release,
526};
527
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700528/**
529 * cdev_alloc() - allocate a cdev structure
530 *
531 * Allocates and returns a cdev structure, or NULL on failure.
532 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533struct cdev *cdev_alloc(void)
534{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800535 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700538 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 }
540 return p;
541}
542
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700543/**
544 * cdev_init() - initialize a cdev structure
545 * @cdev: the structure to initialize
546 * @fops: the file_operations for this device
547 *
548 * Initializes @cdev, remembering @fops, making it ready to add to the
549 * system with cdev_add().
550 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800551void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552{
553 memset(cdev, 0, sizeof *cdev);
554 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700555 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 cdev->ops = fops;
557}
558
559static struct kobject *base_probe(dev_t dev, int *part, void *data)
560{
561 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
562 /* Make old-style 2.4 aliases work */
563 request_module("char-major-%d", MAJOR(dev));
564 return NULL;
565}
566
567void __init chrdev_init(void)
568{
569 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700570 bdi_init(&directly_mappable_cdev_bdi);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571}
572
573
574/* Let modules do char dev stuff */
575EXPORT_SYMBOL(register_chrdev_region);
576EXPORT_SYMBOL(unregister_chrdev_region);
577EXPORT_SYMBOL(alloc_chrdev_region);
578EXPORT_SYMBOL(cdev_init);
579EXPORT_SYMBOL(cdev_alloc);
580EXPORT_SYMBOL(cdev_del);
581EXPORT_SYMBOL(cdev_add);
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400582EXPORT_SYMBOL(cdev_index);
Tejun Heo1905b1b2009-08-06 18:13:23 +0900583EXPORT_SYMBOL(__register_chrdev);
584EXPORT_SYMBOL(__unregister_chrdev);
David Howells5da61852006-09-27 01:50:16 -0700585EXPORT_SYMBOL(directly_mappable_cdev_bdi);