blob: f77f7702fabe1e2ab0a21f6ef0b9dd36247a9f50 [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 |
Jan Kara371d2172010-09-21 11:49:01 +020043 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
44 /* no writeback happens */
45 BDI_CAP_NO_ACCT_AND_WRITEBACK),
David Howells5da61852006-09-27 01:50:16 -070046};
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048static struct kobj_map *cdev_map;
49
Jes Sorensen58383af2006-02-06 14:12:43 -080050static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52static struct char_device_struct {
53 struct char_device_struct *next;
54 unsigned int major;
55 unsigned int baseminor;
56 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080057 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080059} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61/* index in the above */
Yang Zhange61eb2e2010-12-17 09:00:18 +010062static inline int major_to_index(unsigned major)
Linus Torvalds1da177e2005-04-16 15:20:36 -070063{
Joe Korty68eef3b2006-03-31 02:30:32 -080064 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065}
66
Joe Korty68eef3b2006-03-31 02:30:32 -080067#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080068
Joe Korty68eef3b2006-03-31 02:30:32 -080069void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
71 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Joe Korty68eef3b2006-03-31 02:30:32 -080073 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
74 mutex_lock(&chrdevs_lock);
75 for (cd = chrdevs[offset]; cd; cd = cd->next)
76 seq_printf(f, "%3d %s\n", cd->major, cd->name);
77 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 }
Neil Horman7170be52006-01-14 13:20:38 -080079}
80
Joe Korty68eef3b2006-03-31 02:30:32 -080081#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
83/*
84 * Register a single major with a specified minor range.
85 *
86 * If major == 0 this functions will dynamically allocate a major and return
87 * its number.
88 *
89 * If major > 0 this function will attempt to reserve the passed range of
90 * minors and will return zero on success.
91 *
92 * Returns a -ve errno on failure.
93 */
94static struct char_device_struct *
95__register_chrdev_region(unsigned int major, unsigned int baseminor,
96 int minorct, const char *name)
97{
98 struct char_device_struct *cd, **cp;
99 int ret = 0;
100 int i;
101
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800102 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 if (cd == NULL)
104 return ERR_PTR(-ENOMEM);
105
Jes Sorensen58383af2006-02-06 14:12:43 -0800106 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107
108 /* temporary */
109 if (major == 0) {
110 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
111 if (chrdevs[i] == NULL)
112 break;
113 }
114
115 if (i == 0) {
116 ret = -EBUSY;
117 goto out;
118 }
119 major = i;
120 ret = major;
121 }
122
123 cd->major = major;
124 cd->baseminor = baseminor;
125 cd->minorct = minorct;
Cyrill Gorcunov8c4018882009-01-06 14:41:08 -0800126 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
128 i = major_to_index(major);
129
130 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
131 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700132 ((*cp)->major == major &&
133 (((*cp)->baseminor >= baseminor) ||
134 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700136
137 /* Check for overlapping minor ranges. */
138 if (*cp && (*cp)->major == major) {
139 int old_min = (*cp)->baseminor;
140 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
141 int new_min = baseminor;
142 int new_max = baseminor + minorct - 1;
143
144 /* New driver overlaps from the left. */
145 if (new_max >= old_min && new_max <= old_max) {
146 ret = -EBUSY;
147 goto out;
148 }
149
150 /* New driver overlaps from the right. */
151 if (new_min <= old_max && new_min >= old_min) {
152 ret = -EBUSY;
153 goto out;
154 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700156
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 cd->next = *cp;
158 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800159 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 return cd;
161out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800162 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 kfree(cd);
164 return ERR_PTR(ret);
165}
166
167static struct char_device_struct *
168__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
169{
170 struct char_device_struct *cd = NULL, **cp;
171 int i = major_to_index(major);
172
Jes Sorensen58383af2006-02-06 14:12:43 -0800173 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
175 if ((*cp)->major == major &&
176 (*cp)->baseminor == baseminor &&
177 (*cp)->minorct == minorct)
178 break;
179 if (*cp) {
180 cd = *cp;
181 *cp = cd->next;
182 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800183 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 return cd;
185}
186
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700187/**
188 * register_chrdev_region() - register a range of device numbers
189 * @from: the first in the desired range of device numbers; must include
190 * the major number.
191 * @count: the number of consecutive device numbers required
192 * @name: the name of the device or driver.
193 *
194 * Return value is zero on success, a negative error code on failure.
195 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196int register_chrdev_region(dev_t from, unsigned count, const char *name)
197{
198 struct char_device_struct *cd;
199 dev_t to = from + count;
200 dev_t n, next;
201
202 for (n = from; n < to; n = next) {
203 next = MKDEV(MAJOR(n)+1, 0);
204 if (next > to)
205 next = to;
206 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
207 next - n, name);
208 if (IS_ERR(cd))
209 goto fail;
210 }
211 return 0;
212fail:
213 to = n;
214 for (n = from; n < to; n = next) {
215 next = MKDEV(MAJOR(n)+1, 0);
216 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
217 }
218 return PTR_ERR(cd);
219}
220
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700221/**
222 * alloc_chrdev_region() - register a range of char device numbers
223 * @dev: output parameter for first assigned number
224 * @baseminor: first of the requested range of minor numbers
225 * @count: the number of minor numbers required
226 * @name: the name of the associated device or driver
227 *
228 * Allocates a range of char device numbers. The major number will be
229 * chosen dynamically, and returned (along with the first minor number)
230 * in @dev. Returns zero or a negative error code.
231 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
233 const char *name)
234{
235 struct char_device_struct *cd;
236 cd = __register_chrdev_region(0, baseminor, count, name);
237 if (IS_ERR(cd))
238 return PTR_ERR(cd);
239 *dev = MKDEV(cd->major, cd->baseminor);
240 return 0;
241}
242
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700243/**
Tejun Heo1905b1b2009-08-06 18:13:23 +0900244 * __register_chrdev() - create and register a cdev occupying a range of minors
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700245 * @major: major device number or 0 for dynamic allocation
Tejun Heo1905b1b2009-08-06 18:13:23 +0900246 * @baseminor: first of the requested range of minor numbers
247 * @count: the number of minor numbers required
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700248 * @name: name of this range of devices
249 * @fops: file operations associated with this devices
250 *
251 * If @major == 0 this functions will dynamically allocate a major and return
252 * its number.
253 *
254 * If @major > 0 this function will attempt to reserve a device with the given
255 * major number and will return zero on success.
256 *
257 * Returns a -ve errno on failure.
258 *
259 * The name of this device has nothing to do with the name of the device in
260 * /dev. It only helps to keep track of the different owners of devices. If
261 * your module name has only one type of devices it's ok to use e.g. the name
262 * of the module here.
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700263 */
Tejun Heo1905b1b2009-08-06 18:13:23 +0900264int __register_chrdev(unsigned int major, unsigned int baseminor,
265 unsigned int count, const char *name,
266 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
268 struct char_device_struct *cd;
269 struct cdev *cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 int err = -ENOMEM;
271
Tejun Heo1905b1b2009-08-06 18:13:23 +0900272 cd = __register_chrdev_region(major, baseminor, count, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 if (IS_ERR(cd))
274 return PTR_ERR(cd);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800275
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 cdev = cdev_alloc();
277 if (!cdev)
278 goto out2;
279
280 cdev->owner = fops->owner;
281 cdev->ops = fops;
282 kobject_set_name(&cdev->kobj, "%s", name);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800283
Tejun Heo1905b1b2009-08-06 18:13:23 +0900284 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 if (err)
286 goto out;
287
288 cd->cdev = cdev;
289
290 return major ? 0 : cd->major;
291out:
292 kobject_put(&cdev->kobj);
293out2:
Tejun Heo1905b1b2009-08-06 18:13:23 +0900294 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 return err;
296}
297
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700298/**
299 * unregister_chrdev_region() - return a range of device numbers
300 * @from: the first in the range of numbers to unregister
301 * @count: the number of device numbers to unregister
302 *
303 * This function will unregister a range of @count device numbers,
304 * starting with @from. The caller should normally be the one who
305 * allocated those numbers in the first place...
306 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307void unregister_chrdev_region(dev_t from, unsigned count)
308{
309 dev_t to = from + count;
310 dev_t n, next;
311
312 for (n = from; n < to; n = next) {
313 next = MKDEV(MAJOR(n)+1, 0);
314 if (next > to)
315 next = to;
316 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
317 }
318}
319
Tejun Heo1905b1b2009-08-06 18:13:23 +0900320/**
321 * __unregister_chrdev - unregister and destroy a cdev
322 * @major: major device number
323 * @baseminor: first of the range of minor numbers
324 * @count: the number of minor numbers this cdev is occupying
325 * @name: name of this range of devices
326 *
327 * Unregister and destroy the cdev occupying the region described by
328 * @major, @baseminor and @count. This function undoes what
329 * __register_chrdev() did.
330 */
331void __unregister_chrdev(unsigned int major, unsigned int baseminor,
332 unsigned int count, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
334 struct char_device_struct *cd;
Tejun Heo1905b1b2009-08-06 18:13:23 +0900335
336 cd = __unregister_chrdev_region(major, baseminor, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 if (cd && cd->cdev)
338 cdev_del(cd->cdev);
339 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340}
341
342static DEFINE_SPINLOCK(cdev_lock);
343
344static struct kobject *cdev_get(struct cdev *p)
345{
346 struct module *owner = p->owner;
347 struct kobject *kobj;
348
349 if (owner && !try_module_get(owner))
350 return NULL;
351 kobj = kobject_get(&p->kobj);
352 if (!kobj)
353 module_put(owner);
354 return kobj;
355}
356
357void cdev_put(struct cdev *p)
358{
359 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700360 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700362 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 }
364}
365
366/*
367 * Called every time a character special file is opened
368 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800369static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370{
Al Viroe84f9e52013-09-22 14:17:15 -0400371 const struct file_operations *fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 struct cdev *p;
373 struct cdev *new = NULL;
374 int ret = 0;
375
376 spin_lock(&cdev_lock);
377 p = inode->i_cdev;
378 if (!p) {
379 struct kobject *kobj;
380 int idx;
381 spin_unlock(&cdev_lock);
382 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
383 if (!kobj)
384 return -ENXIO;
385 new = container_of(kobj, struct cdev, kobj);
386 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600387 /* Check i_cdev again in case somebody beat us to it while
388 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 p = inode->i_cdev;
390 if (!p) {
391 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 list_add(&inode->i_devices, &p->list);
393 new = NULL;
394 } else if (!cdev_get(p))
395 ret = -ENXIO;
396 } else if (!cdev_get(p))
397 ret = -ENXIO;
398 spin_unlock(&cdev_lock);
399 cdev_put(new);
400 if (ret)
401 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200402
403 ret = -ENXIO;
Al Viroe84f9e52013-09-22 14:17:15 -0400404 fops = fops_get(p->ops);
405 if (!fops)
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200406 goto out_cdev_put;
407
Al Viroe84f9e52013-09-22 14:17:15 -0400408 replace_fops(filp, fops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200409 if (filp->f_op->open) {
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800410 ret = filp->f_op->open(inode, filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200411 if (ret)
412 goto out_cdev_put;
413 }
414
415 return 0;
416
417 out_cdev_put:
418 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 return ret;
420}
421
422void cd_forget(struct inode *inode)
423{
424 spin_lock(&cdev_lock);
425 list_del_init(&inode->i_devices);
426 inode->i_cdev = NULL;
427 spin_unlock(&cdev_lock);
428}
429
Adrian Bunk75c96f82005-05-05 16:16:09 -0700430static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431{
432 spin_lock(&cdev_lock);
433 while (!list_empty(&cdev->list)) {
434 struct inode *inode;
435 inode = container_of(cdev->list.next, struct inode, i_devices);
436 list_del_init(&inode->i_devices);
437 inode->i_cdev = NULL;
438 }
439 spin_unlock(&cdev_lock);
440}
441
442/*
443 * Dummy default file-operations: the only thing this does
444 * is contain the open that then fills in the correct operations
445 * depending on the special file...
446 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800447const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 .open = chrdev_open,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200449 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450};
451
452static struct kobject *exact_match(dev_t dev, int *part, void *data)
453{
454 struct cdev *p = data;
455 return &p->kobj;
456}
457
458static int exact_lock(dev_t dev, void *data)
459{
460 struct cdev *p = data;
461 return cdev_get(p) ? 0 : -1;
462}
463
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700464/**
465 * cdev_add() - add a char device to the system
466 * @p: the cdev structure for the device
467 * @dev: the first device number for which this device is responsible
468 * @count: the number of consecutive minor numbers corresponding to this
469 * device
470 *
471 * cdev_add() adds the device represented by @p to the system, making it
472 * live immediately. A negative error code is returned on failure.
473 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474int cdev_add(struct cdev *p, dev_t dev, unsigned count)
475{
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700476 int error;
477
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 p->dev = dev;
479 p->count = count;
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700480
481 error = kobj_map(cdev_map, dev, count, NULL,
482 exact_match, exact_lock, p);
483 if (error)
484 return error;
485
486 kobject_get(p->kobj.parent);
487
488 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489}
490
491static void cdev_unmap(dev_t dev, unsigned count)
492{
493 kobj_unmap(cdev_map, dev, count);
494}
495
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700496/**
497 * cdev_del() - remove a cdev from the system
498 * @p: the cdev structure to be removed
499 *
500 * cdev_del() removes @p from the system, possibly freeing the structure
501 * itself.
502 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503void cdev_del(struct cdev *p)
504{
505 cdev_unmap(p->dev, p->count);
506 kobject_put(&p->kobj);
507}
508
509
510static void cdev_default_release(struct kobject *kobj)
511{
512 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700513 struct kobject *parent = kobj->parent;
514
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 cdev_purge(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700516 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517}
518
519static void cdev_dynamic_release(struct kobject *kobj)
520{
521 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700522 struct kobject *parent = kobj->parent;
523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 cdev_purge(p);
525 kfree(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700526 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527}
528
529static struct kobj_type ktype_cdev_default = {
530 .release = cdev_default_release,
531};
532
533static struct kobj_type ktype_cdev_dynamic = {
534 .release = cdev_dynamic_release,
535};
536
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700537/**
538 * cdev_alloc() - allocate a cdev structure
539 *
540 * Allocates and returns a cdev structure, or NULL on failure.
541 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542struct cdev *cdev_alloc(void)
543{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800544 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700547 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 }
549 return p;
550}
551
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700552/**
553 * cdev_init() - initialize a cdev structure
554 * @cdev: the structure to initialize
555 * @fops: the file_operations for this device
556 *
557 * Initializes @cdev, remembering @fops, making it ready to add to the
558 * system with cdev_add().
559 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800560void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561{
562 memset(cdev, 0, sizeof *cdev);
563 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700564 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 cdev->ops = fops;
566}
567
568static struct kobject *base_probe(dev_t dev, int *part, void *data)
569{
570 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
571 /* Make old-style 2.4 aliases work */
572 request_module("char-major-%d", MAJOR(dev));
573 return NULL;
574}
575
576void __init chrdev_init(void)
577{
578 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
Mikulas Patocka8077c0d2013-10-14 12:14:13 -0400579 if (bdi_init(&directly_mappable_cdev_bdi))
580 panic("Failed to init directly mappable cdev bdi");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581}
582
583
584/* Let modules do char dev stuff */
585EXPORT_SYMBOL(register_chrdev_region);
586EXPORT_SYMBOL(unregister_chrdev_region);
587EXPORT_SYMBOL(alloc_chrdev_region);
588EXPORT_SYMBOL(cdev_init);
589EXPORT_SYMBOL(cdev_alloc);
590EXPORT_SYMBOL(cdev_del);
591EXPORT_SYMBOL(cdev_add);
Tejun Heo1905b1b2009-08-06 18:13:23 +0900592EXPORT_SYMBOL(__register_chrdev);
593EXPORT_SYMBOL(__unregister_chrdev);
David Howells5da61852006-09-27 01:50:16 -0700594EXPORT_SYMBOL(directly_mappable_cdev_bdi);