blob: d6db933df2b27ce43c0fe31d6e35bb0968598891 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
David Howells07f3f05c2006-09-30 20:52:18 +020024#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
David Howells5da61852006-09-27 01:50:16 -070026/*
27 * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
28 * devices
29 * - permits shared-mmap for read, write and/or exec
30 * - does not permit private mmap in NOMMU mode (can't do COW)
31 * - no readahead or I/O queue unplugging required
32 */
33struct backing_dev_info directly_mappable_cdev_bdi = {
Jens Axboed9938312009-06-12 14:45:52 +020034 .name = "char",
David Howells5da61852006-09-27 01:50:16 -070035 .capabilities = (
36#ifdef CONFIG_MMU
37 /* permit private copies of the data to be taken */
38 BDI_CAP_MAP_COPY |
39#endif
40 /* permit direct mmap, for read, write or exec */
41 BDI_CAP_MAP_DIRECT |
42 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
43};
44
Linus Torvalds1da177e2005-04-16 15:20:36 -070045static struct kobj_map *cdev_map;
46
Jes Sorensen58383af2006-02-06 14:12:43 -080047static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
49static struct char_device_struct {
50 struct char_device_struct *next;
51 unsigned int major;
52 unsigned int baseminor;
53 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080054 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080056} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
58/* index in the above */
59static inline int major_to_index(int major)
60{
Joe Korty68eef3b2006-03-31 02:30:32 -080061 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062}
63
Joe Korty68eef3b2006-03-31 02:30:32 -080064#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080065
Joe Korty68eef3b2006-03-31 02:30:32 -080066void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070067{
68 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
Joe Korty68eef3b2006-03-31 02:30:32 -080070 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
71 mutex_lock(&chrdevs_lock);
72 for (cd = chrdevs[offset]; cd; cd = cd->next)
73 seq_printf(f, "%3d %s\n", cd->major, cd->name);
74 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 }
Neil Horman7170be52006-01-14 13:20:38 -080076}
77
Joe Korty68eef3b2006-03-31 02:30:32 -080078#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80/*
81 * Register a single major with a specified minor range.
82 *
83 * If major == 0 this functions will dynamically allocate a major and return
84 * its number.
85 *
86 * If major > 0 this function will attempt to reserve the passed range of
87 * minors and will return zero on success.
88 *
89 * Returns a -ve errno on failure.
90 */
91static struct char_device_struct *
92__register_chrdev_region(unsigned int major, unsigned int baseminor,
93 int minorct, const char *name)
94{
95 struct char_device_struct *cd, **cp;
96 int ret = 0;
97 int i;
98
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080099 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 if (cd == NULL)
101 return ERR_PTR(-ENOMEM);
102
Jes Sorensen58383af2006-02-06 14:12:43 -0800103 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104
105 /* temporary */
106 if (major == 0) {
107 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
108 if (chrdevs[i] == NULL)
109 break;
110 }
111
112 if (i == 0) {
113 ret = -EBUSY;
114 goto out;
115 }
116 major = i;
117 ret = major;
118 }
119
120 cd->major = major;
121 cd->baseminor = baseminor;
122 cd->minorct = minorct;
Cyrill Gorcunov8c4018882009-01-06 14:41:08 -0800123 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
125 i = major_to_index(major);
126
127 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
128 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700129 ((*cp)->major == major &&
130 (((*cp)->baseminor >= baseminor) ||
131 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700133
134 /* Check for overlapping minor ranges. */
135 if (*cp && (*cp)->major == major) {
136 int old_min = (*cp)->baseminor;
137 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
138 int new_min = baseminor;
139 int new_max = baseminor + minorct - 1;
140
141 /* New driver overlaps from the left. */
142 if (new_max >= old_min && new_max <= old_max) {
143 ret = -EBUSY;
144 goto out;
145 }
146
147 /* New driver overlaps from the right. */
148 if (new_min <= old_max && new_min >= old_min) {
149 ret = -EBUSY;
150 goto out;
151 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700153
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 cd->next = *cp;
155 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800156 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 return cd;
158out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800159 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 kfree(cd);
161 return ERR_PTR(ret);
162}
163
164static struct char_device_struct *
165__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
166{
167 struct char_device_struct *cd = NULL, **cp;
168 int i = major_to_index(major);
169
Jes Sorensen58383af2006-02-06 14:12:43 -0800170 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
172 if ((*cp)->major == major &&
173 (*cp)->baseminor == baseminor &&
174 (*cp)->minorct == minorct)
175 break;
176 if (*cp) {
177 cd = *cp;
178 *cp = cd->next;
179 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800180 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 return cd;
182}
183
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700184/**
185 * register_chrdev_region() - register a range of device numbers
186 * @from: the first in the desired range of device numbers; must include
187 * the major number.
188 * @count: the number of consecutive device numbers required
189 * @name: the name of the device or driver.
190 *
191 * Return value is zero on success, a negative error code on failure.
192 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193int register_chrdev_region(dev_t from, unsigned count, const char *name)
194{
195 struct char_device_struct *cd;
196 dev_t to = from + count;
197 dev_t n, next;
198
199 for (n = from; n < to; n = next) {
200 next = MKDEV(MAJOR(n)+1, 0);
201 if (next > to)
202 next = to;
203 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
204 next - n, name);
205 if (IS_ERR(cd))
206 goto fail;
207 }
208 return 0;
209fail:
210 to = n;
211 for (n = from; n < to; n = next) {
212 next = MKDEV(MAJOR(n)+1, 0);
213 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
214 }
215 return PTR_ERR(cd);
216}
217
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700218/**
219 * alloc_chrdev_region() - register a range of char device numbers
220 * @dev: output parameter for first assigned number
221 * @baseminor: first of the requested range of minor numbers
222 * @count: the number of minor numbers required
223 * @name: the name of the associated device or driver
224 *
225 * Allocates a range of char device numbers. The major number will be
226 * chosen dynamically, and returned (along with the first minor number)
227 * in @dev. Returns zero or a negative error code.
228 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
230 const char *name)
231{
232 struct char_device_struct *cd;
233 cd = __register_chrdev_region(0, baseminor, count, name);
234 if (IS_ERR(cd))
235 return PTR_ERR(cd);
236 *dev = MKDEV(cd->major, cd->baseminor);
237 return 0;
238}
239
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700240/**
Tejun Heo1905b1b2009-08-06 18:13:23 +0900241 * __register_chrdev() - create and register a cdev occupying a range of minors
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700242 * @major: major device number or 0 for dynamic allocation
Tejun Heo1905b1b2009-08-06 18:13:23 +0900243 * @baseminor: first of the requested range of minor numbers
244 * @count: the number of minor numbers required
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700245 * @name: name of this range of devices
246 * @fops: file operations associated with this devices
247 *
248 * If @major == 0 this functions will dynamically allocate a major and return
249 * its number.
250 *
251 * If @major > 0 this function will attempt to reserve a device with the given
252 * major number and will return zero on success.
253 *
254 * Returns a -ve errno on failure.
255 *
256 * The name of this device has nothing to do with the name of the device in
257 * /dev. It only helps to keep track of the different owners of devices. If
258 * your module name has only one type of devices it's ok to use e.g. the name
259 * of the module here.
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700260 */
Tejun Heo1905b1b2009-08-06 18:13:23 +0900261int __register_chrdev(unsigned int major, unsigned int baseminor,
262 unsigned int count, const char *name,
263 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264{
265 struct char_device_struct *cd;
266 struct cdev *cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 int err = -ENOMEM;
268
Tejun Heo1905b1b2009-08-06 18:13:23 +0900269 cd = __register_chrdev_region(major, baseminor, count, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 if (IS_ERR(cd))
271 return PTR_ERR(cd);
272
273 cdev = cdev_alloc();
274 if (!cdev)
275 goto out2;
276
277 cdev->owner = fops->owner;
278 cdev->ops = fops;
279 kobject_set_name(&cdev->kobj, "%s", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280
Tejun Heo1905b1b2009-08-06 18:13:23 +0900281 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 if (err)
283 goto out;
284
285 cd->cdev = cdev;
286
287 return major ? 0 : cd->major;
288out:
289 kobject_put(&cdev->kobj);
290out2:
Tejun Heo1905b1b2009-08-06 18:13:23 +0900291 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 return err;
293}
294
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700295/**
296 * unregister_chrdev_region() - return a range of device numbers
297 * @from: the first in the range of numbers to unregister
298 * @count: the number of device numbers to unregister
299 *
300 * This function will unregister a range of @count device numbers,
301 * starting with @from. The caller should normally be the one who
302 * allocated those numbers in the first place...
303 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304void unregister_chrdev_region(dev_t from, unsigned count)
305{
306 dev_t to = from + count;
307 dev_t n, next;
308
309 for (n = from; n < to; n = next) {
310 next = MKDEV(MAJOR(n)+1, 0);
311 if (next > to)
312 next = to;
313 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
314 }
315}
316
Tejun Heo1905b1b2009-08-06 18:13:23 +0900317/**
318 * __unregister_chrdev - unregister and destroy a cdev
319 * @major: major device number
320 * @baseminor: first of the range of minor numbers
321 * @count: the number of minor numbers this cdev is occupying
322 * @name: name of this range of devices
323 *
324 * Unregister and destroy the cdev occupying the region described by
325 * @major, @baseminor and @count. This function undoes what
326 * __register_chrdev() did.
327 */
328void __unregister_chrdev(unsigned int major, unsigned int baseminor,
329 unsigned int count, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330{
331 struct char_device_struct *cd;
Tejun Heo1905b1b2009-08-06 18:13:23 +0900332
333 cd = __unregister_chrdev_region(major, baseminor, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 if (cd && cd->cdev)
335 cdev_del(cd->cdev);
336 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337}
338
339static DEFINE_SPINLOCK(cdev_lock);
340
341static struct kobject *cdev_get(struct cdev *p)
342{
343 struct module *owner = p->owner;
344 struct kobject *kobj;
345
346 if (owner && !try_module_get(owner))
347 return NULL;
348 kobj = kobject_get(&p->kobj);
349 if (!kobj)
350 module_put(owner);
351 return kobj;
352}
353
354void cdev_put(struct cdev *p)
355{
356 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700357 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700359 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 }
361}
362
363/*
364 * Called every time a character special file is opened
365 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800366static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367{
368 struct cdev *p;
369 struct cdev *new = NULL;
370 int ret = 0;
371
372 spin_lock(&cdev_lock);
373 p = inode->i_cdev;
374 if (!p) {
375 struct kobject *kobj;
376 int idx;
377 spin_unlock(&cdev_lock);
378 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
379 if (!kobj)
380 return -ENXIO;
381 new = container_of(kobj, struct cdev, kobj);
382 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600383 /* Check i_cdev again in case somebody beat us to it while
384 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 p = inode->i_cdev;
386 if (!p) {
387 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 list_add(&inode->i_devices, &p->list);
389 new = NULL;
390 } else if (!cdev_get(p))
391 ret = -ENXIO;
392 } else if (!cdev_get(p))
393 ret = -ENXIO;
394 spin_unlock(&cdev_lock);
395 cdev_put(new);
396 if (ret)
397 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200398
399 ret = -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 filp->f_op = fops_get(p->ops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200401 if (!filp->f_op)
402 goto out_cdev_put;
403
404 if (filp->f_op->open) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 ret = filp->f_op->open(inode,filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200406 if (ret)
407 goto out_cdev_put;
408 }
409
410 return 0;
411
412 out_cdev_put:
413 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 return ret;
415}
416
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400417int cdev_index(struct inode *inode)
418{
419 int idx;
420 struct kobject *kobj;
421
422 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
423 if (!kobj)
424 return -1;
425 kobject_put(kobj);
426 return idx;
427}
428
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429void cd_forget(struct inode *inode)
430{
431 spin_lock(&cdev_lock);
432 list_del_init(&inode->i_devices);
433 inode->i_cdev = NULL;
434 spin_unlock(&cdev_lock);
435}
436
Adrian Bunk75c96f82005-05-05 16:16:09 -0700437static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438{
439 spin_lock(&cdev_lock);
440 while (!list_empty(&cdev->list)) {
441 struct inode *inode;
442 inode = container_of(cdev->list.next, struct inode, i_devices);
443 list_del_init(&inode->i_devices);
444 inode->i_cdev = NULL;
445 }
446 spin_unlock(&cdev_lock);
447}
448
449/*
450 * Dummy default file-operations: the only thing this does
451 * is contain the open that then fills in the correct operations
452 * depending on the special file...
453 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800454const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 .open = chrdev_open,
456};
457
458static struct kobject *exact_match(dev_t dev, int *part, void *data)
459{
460 struct cdev *p = data;
461 return &p->kobj;
462}
463
464static int exact_lock(dev_t dev, void *data)
465{
466 struct cdev *p = data;
467 return cdev_get(p) ? 0 : -1;
468}
469
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700470/**
471 * cdev_add() - add a char device to the system
472 * @p: the cdev structure for the device
473 * @dev: the first device number for which this device is responsible
474 * @count: the number of consecutive minor numbers corresponding to this
475 * device
476 *
477 * cdev_add() adds the device represented by @p to the system, making it
478 * live immediately. A negative error code is returned on failure.
479 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480int cdev_add(struct cdev *p, dev_t dev, unsigned count)
481{
482 p->dev = dev;
483 p->count = count;
484 return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
485}
486
487static void cdev_unmap(dev_t dev, unsigned count)
488{
489 kobj_unmap(cdev_map, dev, count);
490}
491
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700492/**
493 * cdev_del() - remove a cdev from the system
494 * @p: the cdev structure to be removed
495 *
496 * cdev_del() removes @p from the system, possibly freeing the structure
497 * itself.
498 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499void cdev_del(struct cdev *p)
500{
501 cdev_unmap(p->dev, p->count);
502 kobject_put(&p->kobj);
503}
504
505
506static void cdev_default_release(struct kobject *kobj)
507{
508 struct cdev *p = container_of(kobj, struct cdev, kobj);
509 cdev_purge(p);
510}
511
512static void cdev_dynamic_release(struct kobject *kobj)
513{
514 struct cdev *p = container_of(kobj, struct cdev, kobj);
515 cdev_purge(p);
516 kfree(p);
517}
518
519static struct kobj_type ktype_cdev_default = {
520 .release = cdev_default_release,
521};
522
523static struct kobj_type ktype_cdev_dynamic = {
524 .release = cdev_dynamic_release,
525};
526
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700527/**
528 * cdev_alloc() - allocate a cdev structure
529 *
530 * Allocates and returns a cdev structure, or NULL on failure.
531 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532struct cdev *cdev_alloc(void)
533{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800534 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700537 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 }
539 return p;
540}
541
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700542/**
543 * cdev_init() - initialize a cdev structure
544 * @cdev: the structure to initialize
545 * @fops: the file_operations for this device
546 *
547 * Initializes @cdev, remembering @fops, making it ready to add to the
548 * system with cdev_add().
549 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800550void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551{
552 memset(cdev, 0, sizeof *cdev);
553 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700554 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 cdev->ops = fops;
556}
557
558static struct kobject *base_probe(dev_t dev, int *part, void *data)
559{
560 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
561 /* Make old-style 2.4 aliases work */
562 request_module("char-major-%d", MAJOR(dev));
563 return NULL;
564}
565
566void __init chrdev_init(void)
567{
568 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700569 bdi_init(&directly_mappable_cdev_bdi);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570}
571
572
573/* Let modules do char dev stuff */
574EXPORT_SYMBOL(register_chrdev_region);
575EXPORT_SYMBOL(unregister_chrdev_region);
576EXPORT_SYMBOL(alloc_chrdev_region);
577EXPORT_SYMBOL(cdev_init);
578EXPORT_SYMBOL(cdev_alloc);
579EXPORT_SYMBOL(cdev_del);
580EXPORT_SYMBOL(cdev_add);
Theodore Ts'o9fd57462009-05-21 16:01:00 -0400581EXPORT_SYMBOL(cdev_index);
Tejun Heo1905b1b2009-08-06 18:13:23 +0900582EXPORT_SYMBOL(__register_chrdev);
583EXPORT_SYMBOL(__unregister_chrdev);
David Howells5da61852006-09-27 01:50:16 -0700584EXPORT_SYMBOL(directly_mappable_cdev_bdi);